/* vi: set sw=4 ts=4: */
/*
 * httpd implementation for busybox
 *
 * Copyright (C) 2002,2003 Glenn Engel <glenne@engel.org>
 * Copyright (C) 2003-2006 Vladimir Oleynik <dzo@simtreas.ru>
 *
 * Licensed under GPLv2 or later, see file LICENSE in this source tree.
 *
 *****************************************************************************
 *
 * Typical usage:
 * For non root user:
 *      httpd -p 8080 -h $HOME/public_html
 * For daemon start from rc script with uid=0:
 *      httpd -u www
 * which is equivalent to (assuming user www has uid 80):
 *      httpd -p 80 -u 80 -h $PWD -c /etc/httpd.conf -r "Web Server Authentication"
 *
 * When an url starts with "/cgi-bin/" it is assumed to be a cgi script.
 * The server changes directory to the location of the script and executes it
 * after setting QUERY_STRING and other environment variables.
 *
 * Doc:
 * "CGI Environment Variables": http://hoohoo.ncsa.uiuc.edu/cgi/env.html
 *
 * The applet can also be invoked as an url arg decoder and html text encoder
 * as follows:
 *      foo=`httpd -d $foo`             # decode "Hello%20World" as "Hello World"
 *      bar=`httpd -e "<Hello World>"`  # encode as "&#60Hello&#32World&#62"
 * Note that url encoding for arguments is not the same as html encoding for
 * presentation.  -d decodes an url-encoded argument while -e encodes in html
 * for page display.
 *
 * httpd.conf has the following format:
 *
 * H:/serverroot     # define the server root. It will override -h
 * A:172.20.         # Allow address from 172.20.0.0/16
 * A:10.0.0.0/25     # Allow any address from 10.0.0.0-10.0.0.127
 * A:10.0.0.0/255.255.255.128  # Allow any address that previous set
 * A:127.0.0.1       # Allow local loopback connections
 * D:*               # Deny from other IP connections
 * E404:/path/e404.html # /path/e404.html is the 404 (not found) error page
 * I:index.html      # Show index.html when a directory is requested
 *
 * P:/url:[http://]hostname[:port]/new/path
 *                   # When /urlXXXXXX is requested, reverse proxy
 *                   # it to http://hostname[:port]/new/pathXXXXXX
 *
 * /cgi-bin:foo:bar  # Require user foo, pwd bar on urls starting with /cgi-bin/
 * /adm:admin:setup  # Require user admin, pwd setup on urls starting with /adm/
 * /adm:toor:PaSsWd  # or user toor, pwd PaSsWd on urls starting with /adm/
 * .au:audio/basic   # additional mime type for audio.au files
 * *.php:/path/php   # run xxx.php through an interpreter
 *
 * A/D may be as a/d or allow/deny - only first char matters.
 * Deny/Allow IP logic:
 *  - Default is to allow all (Allow all (A:*) is a no-op).
 *  - Deny rules take precedence over allow rules.
 *  - "Deny all" rule (D:*) is applied last.
 *
 * Example:
 *   1. Allow only specified addresses
 *     A:172.20          # Allow any address that begins with 172.20.
 *     A:10.10.          # Allow any address that begins with 10.10.
 *     A:127.0.0.1       # Allow local loopback connections
 *     D:*               # Deny from other IP connections
 *
 *   2. Only deny specified addresses
 *     D:1.2.3.        # deny from 1.2.3.0 - 1.2.3.255
 *     D:2.3.4.        # deny from 2.3.4.0 - 2.3.4.255
 *     A:*             # (optional line added for clarity)
 *
 * If a sub directory contains a config file it is parsed and merged with
 * any existing settings as if it was appended to the original configuration.
 *
 * subdir paths are relative to the containing subdir and thus cannot
 * affect the parent rules.
 *
 * Note that since the sub dir is parsed in the forked thread servicing the
 * subdir http request, any merge is discarded when the process exits.  As a
 * result, the subdir settings only have a lifetime of a single request.
 *
 * Custom error pages can contain an absolute path or be relative to
 * 'home_httpd'. Error pages are to be static files (no CGI or script). Error
 * page can only be defined in the root configuration file and are not taken
 * into account in local (directories) config files.
 *
 * If -c is not set, an attempt will be made to open the default
 * root configuration file.  If -c is set and the file is not found, the
 * server exits with an error.
 *
 */
 /* TODO: use TCP_CORK, parse_config() */

#include "libbb.h"
#if ENABLE_FEATURE_HTTPD_USE_SENDFILE
# include <sys/sendfile.h>
#endif
/* amount of buffering in a pipe */
#ifndef PIPE_BUF
# define PIPE_BUF 4096
#endif

#define DEBUG 0

#define IOBUF_SIZE 8192
#if PIPE_BUF >= IOBUF_SIZE
# error "PIPE_BUF >= IOBUF_SIZE"
#endif

#define HEADER_READ_TIMEOUT 60

static const char DEFAULT_PATH_HTTPD_CONF[] ALIGN1 = "/etc";
static const char HTTPD_CONF[] ALIGN1 = "httpd.conf";
static const char HTTP_200[] ALIGN1 = "HTTP/1.0 200 OK\r\n";
static const char index_html[] ALIGN1 = "index.html";

typedef struct has_next_ptr {
        struct has_next_ptr *next;
} has_next_ptr;

/* Must have "next" as a first member */
typedef struct Htaccess {
        struct Htaccess *next;
        char *after_colon;
        char before_colon[1];  /* really bigger, must be last */
} Htaccess;

/* Must have "next" as a first member */
typedef struct Htaccess_IP {
        struct Htaccess_IP *next;
        unsigned ip;
        unsigned mask;
        int allow_deny;
} Htaccess_IP;

/* Must have "next" as a first member */
typedef struct Htaccess_Proxy {
        struct Htaccess_Proxy *next;
        char *url_from;
        char *host_port;
        char *url_to;
} Htaccess_Proxy;

enum {
        HTTP_OK = 200,
        HTTP_PARTIAL_CONTENT = 206,
        HTTP_MOVED_TEMPORARILY = 302,
        HTTP_BAD_REQUEST = 400,       /* malformed syntax */
        HTTP_UNAUTHORIZED = 401, /* authentication needed, respond with auth hdr */
        HTTP_NOT_FOUND = 404,
        HTTP_FORBIDDEN = 403,
        HTTP_REQUEST_TIMEOUT = 408,
        HTTP_NOT_IMPLEMENTED = 501,   /* used for unrecognized requests */
        HTTP_INTERNAL_SERVER_ERROR = 500,
        HTTP_CONTINUE = 100,
#if 0   /* future use */
        HTTP_SWITCHING_PROTOCOLS = 101,
        HTTP_CREATED = 201,
        HTTP_ACCEPTED = 202,
        HTTP_NON_AUTHORITATIVE_INFO = 203,
        HTTP_NO_CONTENT = 204,
        HTTP_MULTIPLE_CHOICES = 300,
        HTTP_MOVED_PERMANENTLY = 301,
        HTTP_NOT_MODIFIED = 304,
        HTTP_PAYMENT_REQUIRED = 402,
        HTTP_BAD_GATEWAY = 502,
        HTTP_SERVICE_UNAVAILABLE = 503, /* overload, maintenance */
#endif
};

static const uint16_t http_response_type[] ALIGN2 = {
        HTTP_OK,
#if ENABLE_FEATURE_HTTPD_RANGES
        HTTP_PARTIAL_CONTENT,
#endif
        HTTP_MOVED_TEMPORARILY,
        HTTP_REQUEST_TIMEOUT,
        HTTP_NOT_IMPLEMENTED,
#if ENABLE_FEATURE_HTTPD_BASIC_AUTH
        HTTP_UNAUTHORIZED,
#endif
        HTTP_NOT_FOUND,
        HTTP_BAD_REQUEST,
        HTTP_FORBIDDEN,
        HTTP_INTERNAL_SERVER_ERROR,
#if 0   /* not implemented */
        HTTP_CREATED,
        HTTP_ACCEPTED,
        HTTP_NO_CONTENT,
        HTTP_MULTIPLE_CHOICES,
        HTTP_MOVED_PERMANENTLY,
        HTTP_NOT_MODIFIED,
        HTTP_BAD_GATEWAY,
        HTTP_SERVICE_UNAVAILABLE,
#endif
};

static const struct {
        const char *name;
        const char *info;
} http_response[ARRAY_SIZE(http_response_type)] = {
        { "OK", NULL },
#if ENABLE_FEATURE_HTTPD_RANGES
        { "Partial Content", NULL },
#endif
        { "Found", NULL },
        { "Request Timeout", "No request appeared within 60 seconds" },
        { "Not Implemented", "The requested method is not recognized" },
#if ENABLE_FEATURE_HTTPD_BASIC_AUTH
        { "Unauthorized", "" },
#endif
        { "Not Found", "The requested URL was not found" },
        { "Bad Request", "Unsupported method" },
        { "Forbidden", ""  },
        { "Internal Server Error", "Internal Server Error" },
#if 0   /* not implemented */
        { "Created" },
        { "Accepted" },
        { "No Content" },
        { "Multiple Choices" },
        { "Moved Permanently" },
        { "Not Modified" },
        { "Bad Gateway", "" },
        { "Service Unavailable", "" },
#endif
};

struct globals {
        int verbose;            /* must be int (used by getopt32) */
        smallint flg_deny_all;

        unsigned rmt_ip;        /* used for IP-based allow/deny rules */
        time_t last_mod;
        char *rmt_ip_str;       /* for $REMOTE_ADDR and $REMOTE_PORT */
        const char *bind_addr_or_port;

        const char *g_query;
        const char *opt_c_configFile;
        const char *home_httpd;
        const char *index_page;

        const char *found_mime_type;
        const char *found_moved_temporarily;
        Htaccess_IP *ip_a_d;    /* config allow/deny lines */

        IF_FEATURE_HTTPD_BASIC_AUTH(const char *g_realm;)
        IF_FEATURE_HTTPD_BASIC_AUTH(char *remoteuser;)
        IF_FEATURE_HTTPD_CGI(char *referer;)
        IF_FEATURE_HTTPD_CGI(char *user_agent;)
        IF_FEATURE_HTTPD_CGI(char *host;)
        IF_FEATURE_HTTPD_CGI(char *http_accept;)
        IF_FEATURE_HTTPD_CGI(char *http_accept_language;)

        off_t file_size;        /* -1 - unknown */
#if ENABLE_FEATURE_HTTPD_RANGES
        off_t range_start;
        off_t range_end;
        off_t range_len;
#endif

#if ENABLE_FEATURE_HTTPD_BASIC_AUTH
        Htaccess *g_auth;       /* config user:password lines */
#endif
        Htaccess *mime_a;       /* config mime types */
#if ENABLE_FEATURE_HTTPD_CONFIG_WITH_SCRIPT_INTERPR
        Htaccess *script_i;     /* config script interpreters */
#endif
        char *iobuf;            /* [IOBUF_SIZE] */
#define hdr_buf bb_common_bufsiz1
        char *hdr_ptr;
        int hdr_cnt;
#if ENABLE_FEATURE_HTTPD_ERROR_PAGES
        const char *http_error_page[ARRAY_SIZE(http_response_type)];
#endif
#if ENABLE_FEATURE_HTTPD_PROXY
        Htaccess_Proxy *proxy;
#endif
#if ENABLE_FEATURE_HTTPD_GZIP
        /* client can handle gzip / we are going to send gzip */
        smallint content_gzip;
#endif
};
#define G (*ptr_to_globals)
#define verbose           (G.verbose          )
#define flg_deny_all      (G.flg_deny_all     )
#define rmt_ip            (G.rmt_ip           )
#define bind_addr_or_port (G.bind_addr_or_port)
#define g_query           (G.g_query          )
#define opt_c_configFile  (G.opt_c_configFile )
#define home_httpd        (G.home_httpd       )
#define index_page        (G.index_page       )
#define found_mime_type   (G.found_mime_type  )
#define found_moved_temporarily (G.found_moved_temporarily)
#define last_mod          (G.last_mod         )
#define ip_a_d            (G.ip_a_d           )
#define g_realm           (G.g_realm          )
#define remoteuser        (G.remoteuser       )
#define referer           (G.referer          )
#define user_agent        (G.user_agent       )
#define host              (G.host             )
#define http_accept       (G.http_accept      )
#define http_accept_language (G.http_accept_language)
#define file_size         (G.file_size        )
#if ENABLE_FEATURE_HTTPD_RANGES
#define range_start       (G.range_start      )
#define range_end         (G.range_end        )
#define range_len         (G.range_len        )
#else
enum {
        range_start = 0,
        range_end = MAXINT(off_t) - 1,
        range_len = MAXINT(off_t),
};
#endif
#define rmt_ip_str        (G.rmt_ip_str       )
#define g_auth            (G.g_auth           )
#define mime_a            (G.mime_a           )
#define script_i          (G.script_i         )
#define iobuf             (G.iobuf            )
#define hdr_ptr           (G.hdr_ptr          )
#define hdr_cnt           (G.hdr_cnt          )
#define http_error_page   (G.http_error_page  )
#define proxy             (G.proxy            )
#if ENABLE_FEATURE_HTTPD_GZIP
# define content_gzip     (G.content_gzip     )
#else
# define content_gzip     0
#endif
#define INIT_G() do { \
        SET_PTR_TO_GLOBALS(xzalloc(sizeof(G))); \
        IF_FEATURE_HTTPD_BASIC_AUTH(g_realm = "Web Server Authentication";) \
        bind_addr_or_port = "80"; \
        index_page = index_html; \
        file_size = -1; \
} while (0)


#define STRNCASECMP(a, str) strncasecmp((a), (str), sizeof(str)-1)

/* Prototypes */
enum {
        SEND_HEADERS     = (1 << 0),
        SEND_BODY        = (1 << 1),
        SEND_HEADERS_AND_BODY = SEND_HEADERS + SEND_BODY,
};
static void send_file_and_exit(const char *url, int what) NORETURN;

static void free_llist(has_next_ptr **pptr)
{
        has_next_ptr *cur = *pptr;
        while (cur) {
                has_next_ptr *t = cur;
                cur = cur->next;
                free(t);
        }
        *pptr = NULL;
}

static ALWAYS_INLINE void free_Htaccess_list(Htaccess **pptr)
{
        free_llist((has_next_ptr**)pptr);
}

static ALWAYS_INLINE void free_Htaccess_IP_list(Htaccess_IP **pptr)
{
        free_llist((has_next_ptr**)pptr);
}

/* Returns presumed mask width in bits or < 0 on error.
 * Updates strp, stores IP at provided pointer */
static int scan_ip(const char **strp, unsigned *ipp, unsigned char endc)
{
        const char *p = *strp;
        int auto_mask = 8;
        unsigned ip = 0;
        int j;

        if (*p == '/')
                return -auto_mask;

        for (j = 0; j < 4; j++) {
                unsigned octet;

                if ((*p < '0' || *p > '9') && *p != '/' && *p)
                        return -auto_mask;
                octet = 0;
                while (*p >= '0' && *p <= '9') {
                        octet *= 10;
                        octet += *p - '0';
                        if (octet > 255)
                                return -auto_mask;
                        p++;
                }
                if (*p == '.')
                        p++;
                if (*p != '/' && *p)
                        auto_mask += 8;
                ip = (ip << 8) | octet;
        }
        if (*p) {
                if (*p != endc)
                        return -auto_mask;
                p++;
                if (*p == '\0')
                        return -auto_mask;
        }
        *ipp = ip;
        *strp = p;
        return auto_mask;
}

/* Returns 0 on success. Stores IP and mask at provided pointers */
static int scan_ip_mask(const char *str, unsigned *ipp, unsigned *maskp)
{
        int i;
        unsigned mask;
        char *p;

        i = scan_ip(&str, ipp, '/');
        if (i < 0)
                return i;

        if (*str) {
                /* there is /xxx after dotted-IP address */
                i = bb_strtou(str, &p, 10);
                if (*p == '.') {
                        /* 'xxx' itself is dotted-IP mask, parse it */
                        /* (return 0 (success) only if it has N.N.N.N form) */
                        return scan_ip(&str, maskp, '\0') - 32;
                }
                if (*p)
                        return -1;
        }

        if (i > 32)
                return -1;

        if (sizeof(unsigned) == 4 && i == 32) {
                /* mask >>= 32 below may not work */
                mask = 0;
        } else {
                mask = 0xffffffff;
                mask >>= i;
        }
        /* i == 0 -> *maskp = 0x00000000
         * i == 1 -> *maskp = 0x80000000
         * i == 4 -> *maskp = 0xf0000000
         * i == 31 -> *maskp = 0xfffffffe
         * i == 32 -> *maskp = 0xffffffff */
        *maskp = (uint32_t)(~mask);
        return 0;
}

/*
 * Parse configuration file into in-memory linked list.
 *
 * Any previous IP rules are discarded.
 * If the flag argument is not SUBDIR_PARSE then all /path and mime rules
 * are also discarded.  That is, previous settings are retained if flag is
 * SUBDIR_PARSE.
 * Error pages are only parsed on the main config file.
 *
 * path   Path where to look for httpd.conf (without filename).
 * flag   Type of the parse request.
 */
/* flag param: */
enum {
        FIRST_PARSE    = 0, /* path will be "/etc" */
        SIGNALED_PARSE = 1, /* path will be "/etc" */
        SUBDIR_PARSE   = 2, /* path will be derived from URL */
};
static void parse_conf(const char *path, int flag)
{
        /* internally used extra flag state */
        enum { TRY_CURDIR_PARSE = 3 };

        FILE *f;
        const char *filename;
        char buf[160];

        /* discard old rules */
        free_Htaccess_IP_list(&ip_a_d);
        flg_deny_all = 0;
        /* retain previous auth and mime config only for subdir parse */
        if (flag != SUBDIR_PARSE) {
                free_Htaccess_list(&mime_a);
#if ENABLE_FEATURE_HTTPD_BASIC_AUTH
                free_Htaccess_list(&g_auth);
#endif
#if ENABLE_FEATURE_HTTPD_CONFIG_WITH_SCRIPT_INTERPR
                free_Htaccess_list(&script_i);
#endif
        }

        filename = opt_c_configFile;
        if (flag == SUBDIR_PARSE || filename == NULL) {
                filename = alloca(strlen(path) + sizeof(HTTPD_CONF) + 2);
                sprintf((char *)filename, "%s/%s", path, HTTPD_CONF);
        }

        while ((f = fopen_for_read(filename)) == NULL) {
                if (flag >= SUBDIR_PARSE) { /* SUBDIR or TRY_CURDIR */
                        /* config file not found, no changes to config */
                        return;
                }
                if (flag == FIRST_PARSE) {
                        /* -c CONFFILE given, but CONFFILE doesn't exist? */
                        if (opt_c_configFile)
                                bb_simple_perror_msg_and_die(opt_c_configFile);
                        /* else: no -c, thus we looked at /etc/httpd.conf,
                         * and it's not there. try ./httpd.conf: */
                }
                flag = TRY_CURDIR_PARSE;
                filename = HTTPD_CONF;
        }

#if ENABLE_FEATURE_HTTPD_BASIC_AUTH
        /* in "/file:user:pass" lines, we prepend path in subdirs */
        if (flag != SUBDIR_PARSE)
                path = "";
#endif
        /* The lines can be:
         *
         * I:default_index_file
         * H:http_home
         * [AD]:IP[/mask]   # allow/deny, * for wildcard
         * Ennn:error.html  # error page for status nnn
         * P:/url:[http://]hostname[:port]/new/path # reverse proxy
         * .ext:mime/type   # mime type
         * *.php:/path/php  # run xxx.php through an interpreter
         * /file:user:pass  # username and password
         */
        while (fgets(buf, sizeof(buf), f) != NULL) {
                unsigned strlen_buf;
                unsigned char ch;
                char *after_colon;

                { /* remove all whitespace, and # comments */
                        char *p, *p0;

                        p0 = buf;
                        /* skip non-whitespace beginning. Often the whole line
                         * is non-whitespace. We want this case to work fast,
                         * without needless copying, therefore we don't merge
                         * this operation into next while loop. */
                        while ((ch = *p0) != '\0' && ch != '\n' && ch != '#'
                         && ch != ' ' && ch != '\t'
                        ) {
                                p0++;
                        }
                        p = p0;
                        /* if we enter this loop, we have some whitespace.
                         * discard it */
                        while (ch != '\0' && ch != '\n' && ch != '#') {
                                if (ch != ' ' && ch != '\t') {
                                        *p++ = ch;
                                }
                                ch = *++p0;
                        }
                        *p = '\0';
                        strlen_buf = p - buf;
                        if (strlen_buf == 0)
                                continue; /* empty line */
                }

                after_colon = strchr(buf, ':');
                /* strange line? */
                if (after_colon == NULL || *++after_colon == '\0')
                        goto config_error;

                ch = (buf[0] & ~0x20); /* toupper if it's a letter */

                if (ch == 'I') {
                        if (index_page != index_html)
                                free((char*)index_page);
                        index_page = xstrdup(after_colon);
                        continue;
                }

                /* do not allow jumping around using H in subdir's configs */
                if (flag == FIRST_PARSE && ch == 'H') {
                        home_httpd = xstrdup(after_colon);
                        xchdir(home_httpd);
                        continue;
                }

                if (ch == 'A' || ch == 'D') {
                        Htaccess_IP *pip;

                        if (*after_colon == '*') {
                                if (ch == 'D') {
                                        /* memorize "deny all" */
                                        flg_deny_all = 1;
                                }
                                /* skip assumed "A:*", it is a default anyway */
                                continue;
                        }
                        /* store "allow/deny IP/mask" line */
                        pip = xzalloc(sizeof(*pip));
                        if (scan_ip_mask(after_colon, &pip->ip, &pip->mask)) {
                                /* IP{/mask} syntax error detected, protect all */
                                ch = 'D';
                                pip->mask = 0;
                        }
                        pip->allow_deny = ch;
                        if (ch == 'D') {
                                /* Deny:from_IP - prepend */
                                pip->next = ip_a_d;
                                ip_a_d = pip;
                        } else {
                                /* A:from_IP - append (thus all D's precedes A's) */
                                Htaccess_IP *prev_IP = ip_a_d;
                                if (prev_IP == NULL) {
                                        ip_a_d = pip;
                                } else {
                                        while (prev_IP->next)
                                                prev_IP = prev_IP->next;
                                        prev_IP->next = pip;
                                }
                        }
                        continue;
                }

#if ENABLE_FEATURE_HTTPD_ERROR_PAGES
                if (flag == FIRST_PARSE && ch == 'E') {
                        unsigned i;
                        int status = atoi(buf + 1); /* error status code */

                        if (status < HTTP_CONTINUE) {
                                goto config_error;
                        }
                        /* then error page; find matching status */
                        for (i = 0; i < ARRAY_SIZE(http_response_type); i++) {
                                if (http_response_type[i] == status) {
                                        /* We chdir to home_httpd, thus no need to
                                         * concat_path_file(home_httpd, after_colon)
                                         * here */
                                        http_error_page[i] = xstrdup(after_colon);
                                        break;
                                }
                        }
                        continue;
                }
#endif

#if ENABLE_FEATURE_HTTPD_PROXY
                if (flag == FIRST_PARSE && ch == 'P') {
                        /* P:/url:[http://]hostname[:port]/new/path */
                        char *url_from, *host_port, *url_to;
                        Htaccess_Proxy *proxy_entry;

                        url_from = after_colon;
                        host_port = strchr(after_colon, ':');
                        if (host_port == NULL) {
                                goto config_error;
                        }
                        *host_port++ = '\0';
                        if (strncmp(host_port, "http://", 7) == 0)
                                host_port += 7;
                        if (*host_port == '\0') {
                                goto config_error;
                        }
                        url_to = strchr(host_port, '/');
                        if (url_to == NULL) {
                                goto config_error;
                        }
                        *url_to = '\0';
                        proxy_entry = xzalloc(sizeof(*proxy_entry));
                        proxy_entry->url_from = xstrdup(url_from);
                        proxy_entry->host_port = xstrdup(host_port);
                        *url_to = '/';
                        proxy_entry->url_to = xstrdup(url_to);
                        proxy_entry->next = proxy;
                        proxy = proxy_entry;
                        continue;
                }
#endif
                /* the rest of directives are non-alphabetic,
                 * must avoid using "toupper'ed" ch */
                ch = buf[0];

                if (ch == '.' /* ".ext:mime/type" */
#if ENABLE_FEATURE_HTTPD_CONFIG_WITH_SCRIPT_INTERPR
                 || (ch == '*' && buf[1] == '.') /* "*.php:/path/php" */
#endif
                ) {
                        char *p;
                        Htaccess *cur;

                        cur = xzalloc(sizeof(*cur) /* includes space for NUL */ + strlen_buf);
                        strcpy(cur->before_colon, buf);
                        p = cur->before_colon + (after_colon - buf);
                        p[-1] = '\0';
                        cur->after_colon = p;
                        if (ch == '.') {
                                /* .mime line: prepend to mime_a list */
                                cur->next = mime_a;
                                mime_a = cur;
                        }
#if ENABLE_FEATURE_HTTPD_CONFIG_WITH_SCRIPT_INTERPR
                        else {
                                /* script interpreter line: prepend to script_i list */
                                cur->next = script_i;
                                script_i = cur;
                        }
#endif
                        continue;
                }

#if ENABLE_FEATURE_HTTPD_BASIC_AUTH
                if (ch == '/') { /* "/file:user:pass" */
                        char *p;
                        Htaccess *cur;
                        unsigned file_len;

                        /* note: path is "" unless we are in SUBDIR parse,
                         * otherwise it does NOT start with "/" */
                        cur = xzalloc(sizeof(*cur) /* includes space for NUL */
                                + 1 + strlen(path)
                                + strlen_buf
                                );
                        /* form "/path/file" */
                        sprintf(cur->before_colon, "/%s%.*s",
                                path,
                                (int) (after_colon - buf - 1), /* includes "/", but not ":" */
                                buf);
                        /* canonicalize it */
                        p = bb_simplify_abs_path_inplace(cur->before_colon);
                        file_len = p - cur->before_colon;
                        /* add "user:pass" after NUL */
                        strcpy(++p, after_colon);
                        cur->after_colon = p;

                        /* insert cur into g_auth */
                        /* g_auth is sorted by decreased filename length */
                        {
                                Htaccess *auth, **authp;

                                authp = &g_auth;
                                while ((auth = *authp) != NULL) {
                                        if (file_len >= strlen(auth->before_colon)) {
                                                /* insert cur before auth */
                                                cur->next = auth;
                                                break;
                                        }
                                        authp = &auth->next;
                                }
                                *authp = cur;
                        }
                        continue;
                }
#endif /* BASIC_AUTH */

                /* the line is not recognized */
 config_error:
                bb_error_msg("config error '%s' in '%s'", buf, filename);
         } /* while (fgets) */

         fclose(f);
}

#if ENABLE_FEATURE_HTTPD_ENCODE_URL_STR
/*
 * Given a string, html-encode special characters.
 * This is used for the -e command line option to provide an easy way
 * for scripts to encode result data without confusing browsers.  The
 * returned string pointer is memory allocated by malloc().
 *
 * Returns a pointer to the encoded string (malloced).
 */
static char *encodeString(const char *string)
{
        /* take the simple route and encode everything */
        /* could possibly scan once to get length.     */
        int len = strlen(string);
        char *out = xmalloc(len * 6 + 1);
        char *p = out;
        char ch;

        while ((ch = *string++) != '\0') {
                /* very simple check for what to encode */
                if (isalnum(ch))
                        *p++ = ch;
                else
                        p += sprintf(p, "&#%d;", (unsigned char) ch);
        }
        *p = '\0';
        return out;
}
#endif

/*
 * Given a URL encoded string, convert it to plain ascii.
 * Since decoding always makes strings smaller, the decode is done in-place.
 * Thus, callers should xstrdup() the argument if they do not want the
 * argument modified.  The return is the original pointer, allowing this
 * function to be easily used as arguments to other functions.
 *
 * string    The first string to decode.
 * option_d  1 if called for httpd -d
 *
 * Returns a pointer to the decoded string (same as input).
 */
static unsigned hex_to_bin(unsigned char c)
{
        unsigned v;

        v = c - '0';
        if (v <= 9)
                return v;
        /* c | 0x20: letters to lower case, non-letters
         * to (potentially different) non-letters */
        v = (unsigned)(c | 0x20) - 'a';
        if (v <= 5)
                return v + 10;
        return ~0;
/* For testing:
void t(char c) { printf("'%c'(%u) %u\n", c, c, hex_to_bin(c)); }
int main() { t(0x10); t(0x20); t('0'); t('9'); t('A'); t('F'); t('a'); t('f');
t('0'-1); t('9'+1); t('A'-1); t('F'+1); t('a'-1); t('f'+1); return 0; }
*/
}
static char *decodeString(char *orig, int option_d)
{
        /* note that decoded string is always shorter than original */
        char *string = orig;
        char *ptr = string;
        char c;

        while ((c = *ptr++) != '\0') {
                unsigned v;

                if (option_d && c == '+') {
                        *string++ = ' ';
                        continue;
                }
                if (c != '%') {
                        *string++ = c;
                        continue;
                }
                v = hex_to_bin(ptr[0]);
                if (v > 15) {
 bad_hex:
                        if (!option_d)
                                return NULL;
                        *string++ = '%';
                        continue;
                }
                v = (v * 16) | hex_to_bin(ptr[1]);
                if (v > 255)
                        goto bad_hex;
                if (!option_d && (v == '/' || v == '\0')) {
                        /* caller takes it as indication of invalid
                         * (dangerous wrt exploits) chars */
                        return orig + 1;
                }
                *string++ = v;
                ptr += 2;
        }
        *string = '\0';
        return orig;
}

#if ENABLE_FEATURE_HTTPD_BASIC_AUTH
/*
 * Decode a base64 data stream as per rfc1521.
 * Note that the rfc states that non base64 chars are to be ignored.
 * Since the decode always results in a shorter size than the input,
 * it is OK to pass the input arg as an output arg.
 * Parameter: a pointer to a base64 encoded string.
 * Decoded data is stored in-place.
 */
static void decodeBase64(char *Data)
{
        const unsigned char *in = (const unsigned char *)Data;
        /* The decoded size will be at most 3/4 the size of the encoded */
        unsigned ch = 0;
        int i = 0;

        while (*in) {
                int t = *in++;

                if (t >= '0' && t <= '9')
                        t = t - '0' + 52;
                else if (t >= 'A' && t <= 'Z')
                        t = t - 'A';
                else if (t >= 'a' && t <= 'z')
                        t = t - 'a' + 26;
                else if (t == '+')
                        t = 62;
                else if (t == '/')
                        t = 63;
                else if (t == '=')
                        t = 0;
                else
                        continue;

                ch = (ch << 6) | t;
                i++;
                if (i == 4) {
                        *Data++ = (char) (ch >> 16);
                        *Data++ = (char) (ch >> 8);
                        *Data++ = (char) ch;
                        i = 0;
                }
        }
        *Data = '\0';
}
#endif

/*
 * Create a listen server socket on the designated port.
 */
static int openServer(void)
{
        unsigned n = bb_strtou(bind_addr_or_port, NULL, 10);
        if (!errno && n && n <= 0xffff)
                n = create_and_bind_stream_or_die(NULL, n);
        else
                n = create_and_bind_stream_or_die(bind_addr_or_port, 80);
        xlisten(n, 9);
        return n;
}

/*
 * Log the connection closure and exit.
 */
static void log_and_exit(void) NORETURN;
static void log_and_exit(void)
{
        /* Paranoia. IE said to be buggy. It may send some extra data
         * or be confused by us just exiting without SHUT_WR. Oh well. */
        shutdown(1, SHUT_WR);
        /* Why??
        (this also messes up stdin when user runs httpd -i from terminal)
        ndelay_on(0);
        while (read(STDIN_FILENO, iobuf, IOBUF_SIZE) > 0)
                continue;
        */

        if (verbose > 2)
                bb_error_msg("closed");
        _exit(xfunc_error_retval);
}

/*
 * Create and send HTTP response headers.
 * The arguments are combined and sent as one write operation.  Note that
 * IE will puke big-time if the headers are not sent in one packet and the
 * second packet is delayed for any reason.
 * responseNum - the result code to send.
 */
static void send_headers(int responseNum)
{
        static const char RFC1123FMT[] ALIGN1 = "%a, %d %b %Y %H:%M:%S GMT";

        const char *responseString = "";
        const char *infoString = NULL;
        const char *mime_type;
#if ENABLE_FEATURE_HTTPD_ERROR_PAGES
        const char *error_page = NULL;
#endif
        unsigned i;
        time_t timer = time(NULL);
        char tmp_str[80];
        int len;

        for (i = 0; i < ARRAY_SIZE(http_response_type); i++) {
                if (http_response_type[i] == responseNum) {
                        responseString = http_response[i].name;
                        infoString = http_response[i].info;
#if ENABLE_FEATURE_HTTPD_ERROR_PAGES
                        error_page = http_error_page[i];
#endif
                        break;
                }
        }
        /* error message is HTML */
        mime_type = responseNum == HTTP_OK ?
                                found_mime_type : "text/html";

        if (verbose)
                bb_error_msg("response:%u", responseNum);

        /* emit the current date */
        strftime(tmp_str, sizeof(tmp_str), RFC1123FMT, gmtime(&timer));
        len = sprintf(iobuf,
                        "HTTP/1.0 %d %s\r\nContent-type: %s\r\n"
                        "Date: %s\r\nConnection: close\r\n",
                        responseNum, responseString, mime_type, tmp_str);

#if ENABLE_FEATURE_HTTPD_BASIC_AUTH
        if (responseNum == HTTP_UNAUTHORIZED) {
                len += sprintf(iobuf + len,
                                "WWW-Authenticate: Basic realm=\"%s\"\r\n",
                                g_realm);
        }
#endif

        if (responseNum == HTTP_MOVED_TEMPORARILY) {
                len += sprintf(iobuf + len, "Location: %s/%s%s\r\n",
                                found_moved_temporarily,
                                (g_query ? "?" : ""),
                                (g_query ? g_query : ""));
        }

#if ENABLE_FEATURE_HTTPD_ERROR_PAGES
        if (error_page && access(error_page, R_OK) == 0) {
                strcat(iobuf, "\r\n");
                len += 2;

                if (DEBUG)
                        fprintf(stderr, "headers: '%s'\n", iobuf);
                full_write(STDOUT_FILENO, iobuf, len);
                if (DEBUG)
                        fprintf(stderr, "writing error page: '%s'\n", error_page);
                return send_file_and_exit(error_page, SEND_BODY);
        }
#endif

        if (file_size != -1) {    /* file */
                strftime(tmp_str, sizeof(tmp_str), RFC1123FMT, gmtime(&last_mod));
#if ENABLE_FEATURE_HTTPD_RANGES
                if (responseNum == HTTP_PARTIAL_CONTENT) {
                        len += sprintf(iobuf + len, "Content-Range: bytes %"OFF_FMT"u-%"OFF_FMT"u/%"OFF_FMT"u\r\n",
                                        range_start,
                                        range_end,
                                        file_size);
                        file_size = range_end - range_start + 1;
                }
#endif
                len += sprintf(iobuf + len,
#if ENABLE_FEATURE_HTTPD_RANGES
                        "Accept-Ranges: bytes\r\n"
#endif
                        "Last-Modified: %s\r\n%s %"OFF_FMT"u\r\n",
                                tmp_str,
                                content_gzip ? "Transfer-length:" : "Content-length:",
                                file_size
                );
        }

        if (content_gzip)
                len += sprintf(iobuf + len, "Content-Encoding: gzip\r\n");

        iobuf[len++] = '\r';
        iobuf[len++] = '\n';
        if (infoString) {
                len += sprintf(iobuf + len,
                                "<HTML><HEAD><TITLE>%d %s</TITLE></HEAD>\n"
                                "<BODY><H1>%d %s</H1>\n%s\n</BODY></HTML>\n",
                                responseNum, responseString,
                                responseNum, responseString, infoString);
        }
        if (DEBUG)
                fprintf(stderr, "headers: '%s'\n", iobuf);
        if (full_write(STDOUT_FILENO, iobuf, len) != len) {
                if (verbose > 1)
                        bb_perror_msg("error");
                log_and_exit();
        }
}

static void send_headers_and_exit(int responseNum) NORETURN;
static void send_headers_and_exit(int responseNum)
{
        send_headers(responseNum);
        log_and_exit();
}

/*
 * Read from the socket until '\n' or EOF. '\r' chars are removed.
 * '\n' is replaced with NUL.
 * Return number of characters read or 0 if nothing is read
 * ('\r' and '\n' are not counted).
 * Data is returned in iobuf.
 */
static int get_line(void)
{
        int count = 0;
        char c;

        alarm(HEADER_READ_TIMEOUT);
        while (1) {
                if (hdr_cnt <= 0) {
                        hdr_cnt = safe_read(STDIN_FILENO, hdr_buf, sizeof(hdr_buf));
                        if (hdr_cnt <= 0)
                                break;
                        hdr_ptr = hdr_buf;
                }
                iobuf[count] = c = *hdr_ptr++;
                hdr_cnt--;

                if (c == '\r')
                        continue;
                if (c == '\n') {
                        iobuf[count] = '\0';
                        break;
                }
                if (count < (IOBUF_SIZE - 1))      /* check overflow */
                        count++;
        }
        return count;
}

#if ENABLE_FEATURE_HTTPD_CGI || ENABLE_FEATURE_HTTPD_PROXY

/* gcc 4.2.1 fares better with NOINLINE */
static NOINLINE void cgi_io_loop_and_exit(int fromCgi_rd, int toCgi_wr, int post_len) NORETURN;
static NOINLINE void cgi_io_loop_and_exit(int fromCgi_rd, int toCgi_wr, int post_len)
{
        enum { FROM_CGI = 1, TO_CGI = 2 }; /* indexes in pfd[] */
        struct pollfd pfd[3];
        int out_cnt; /* we buffer a bit of initial CGI output */
        int count;

        /* iobuf is used for CGI -> network data,
         * hdr_buf is for network -> CGI data (POSTDATA) */

        /* If CGI dies, we still want to correctly finish reading its output
         * and send it to the peer. So please no SIGPIPEs! */
        signal(SIGPIPE, SIG_IGN);

        // We inconsistently handle a case when more POSTDATA from network
        // is coming than we expected. We may give *some part* of that
        // extra data to CGI.

        //if (hdr_cnt > post_len) {
        //      /* We got more POSTDATA from network than we expected */
        //      hdr_cnt = post_len;
        //}
        post_len -= hdr_cnt;
        /* post_len - number of POST bytes not yet read from network */

        /* NB: breaking out of this loop jumps to log_and_exit() */
        out_cnt = 0;
        while (1) {
                memset(pfd, 0, sizeof(pfd));

                pfd[FROM_CGI].fd = fromCgi_rd;
                pfd[FROM_CGI].events = POLLIN;

                if (toCgi_wr) {
                        pfd[TO_CGI].fd = toCgi_wr;
                        if (hdr_cnt > 0) {
                                pfd[TO_CGI].events = POLLOUT;
                        } else if (post_len > 0) {
                                pfd[0].events = POLLIN;
                        } else {
                                /* post_len <= 0 && hdr_cnt <= 0:
                                 * no more POST data to CGI,
                                 * let CGI see EOF on CGI's stdin */
                                if (toCgi_wr != fromCgi_rd)
                                        close(toCgi_wr);
                                toCgi_wr = 0;
                        }
                }

                /* Now wait on the set of sockets */
                count = safe_poll(pfd, toCgi_wr ? TO_CGI+1 : FROM_CGI+1, -1);
                if (count <= 0) {
#if 0
                        if (safe_waitpid(pid, &status, WNOHANG) <= 0) {
                                /* Weird. CGI didn't exit and no fd's
                                 * are ready, yet poll returned?! */
                                continue;
                        }
                        if (DEBUG && WIFEXITED(status))
                                bb_error_msg("CGI exited, status=%d", WEXITSTATUS(status));
                        if (DEBUG && WIFSIGNALED(status))
                                bb_error_msg("CGI killed, signal=%d", WTERMSIG(status));
#endif
                        break;
                }

                if (pfd[TO_CGI].revents) {
                        /* hdr_cnt > 0 here due to the way pfd[TO_CGI].events set */
                        /* Have data from peer and can write to CGI */
                        count = safe_write(toCgi_wr, hdr_ptr, hdr_cnt);
                        /* Doesn't happen, we dont use nonblocking IO here
                         *if (count < 0 && errno == EAGAIN) {
                         *      ...
                         *} else */
                        if (count > 0) {
                                hdr_ptr += count;
                                hdr_cnt -= count;
                        } else {
                                /* EOF/broken pipe to CGI, stop piping POST data */
                                hdr_cnt = post_len = 0;
                        }
                }

                if (pfd[0].revents) {
                        /* post_len > 0 && hdr_cnt == 0 here */
                        /* We expect data, prev data portion is eaten by CGI
                         * and there *is* data to read from the peer
                         * (POSTDATA) */
                        //count = post_len > (int)sizeof(hdr_buf) ? (int)sizeof(hdr_buf) : post_len;
                        //count = safe_read(STDIN_FILENO, hdr_buf, count);
                        count = safe_read(STDIN_FILENO, hdr_buf, sizeof(hdr_buf));
                        if (count > 0) {
                                hdr_cnt = count;
                                hdr_ptr = hdr_buf;
                                post_len -= count;
                        } else {
                                /* no more POST data can be read */
                                post_len = 0;
                        }
                }

                if (pfd[FROM_CGI].revents) {
                        /* There is something to read from CGI */
                        char *rbuf = iobuf;

                        /* Are we still buffering CGI output? */
                        if (out_cnt >= 0) {
                                /* HTTP_200[] has single "\r\n" at the end.
                                 * According to http://hoohoo.ncsa.uiuc.edu/cgi/out.html,
                                 * CGI scripts MUST send their own header terminated by
                                 * empty line, then data. That's why we have only one
                                 * <cr><lf> pair here. We will output "200 OK" line
                                 * if needed, but CGI still has to provide blank line
                                 * between header and body */

                                /* Must use safe_read, not full_read, because
                                 * CGI may output a few first bytes and then wait
                                 * for POSTDATA without closing stdout.
                                 * With full_read we may wait here forever. */
                                count = safe_read(fromCgi_rd, rbuf + out_cnt, PIPE_BUF - 8);
                                if (count <= 0) {
                                        /* eof (or error) and there was no "HTTP",
                                         * so write it, then write received data */
                                        if (out_cnt) {
                                                full_write(STDOUT_FILENO, HTTP_200, sizeof(HTTP_200)-1);
                                                full_write(STDOUT_FILENO, rbuf, out_cnt);
                                        }
                                        break; /* CGI stdout is closed, exiting */
                                }
                                out_cnt += count;
                                count = 0;
                                /* "Status" header format is: "Status: 302 Redirected\r\n" */
                                if (out_cnt >= 8 && memcmp(rbuf, "Status: ", 8) == 0) {
                                        /* send "HTTP/1.0 " */
                                        if (full_write(STDOUT_FILENO, HTTP_200, 9) != 9)
                                                break;
                                        rbuf += 8; /* skip "Status: " */
                                        count = out_cnt - 8;
                                        out_cnt = -1; /* buffering off */
                                } else if (out_cnt >= 4) {
                                        /* Did CGI add "HTTP"? */
                                        if (memcmp(rbuf, HTTP_200, 4) != 0) {
                                                /* there is no "HTTP", do it ourself */
                                                if (full_write(STDOUT_FILENO, HTTP_200, sizeof(HTTP_200)-1) != sizeof(HTTP_200)-1)
                                                        break;
                                        }
                                        /* Commented out:
                                        if (!strstr(rbuf, "ontent-")) {
                                                full_write(s, "Content-type: text/plain\r\n\r\n", 28);
                                        }
                                         * Counter-example of valid CGI without Content-type:
                                         * echo -en "HTTP/1.0 302 Found\r\n"
                                         * echo -en "Location: http://www.busybox.net\r\n"
                                         * echo -en "\r\n"
                                         */
                                        count = out_cnt;
                                        out_cnt = -1; /* buffering off */
                                }
                        } else {
                                count = safe_read(fromCgi_rd, rbuf, PIPE_BUF);
                                if (count <= 0)
                                        break;  /* eof (or error) */
                        }
                        if (full_write(STDOUT_FILENO, rbuf, count) != count)
                                break;
                        if (DEBUG)
                                fprintf(stderr, "cgi read %d bytes: '%.*s'\n", count, count, rbuf);
                } /* if (pfd[FROM_CGI].revents) */
        } /* while (1) */
        log_and_exit();
}
#endif

#if ENABLE_FEATURE_HTTPD_CGI

static void setenv1(const char *name, const char *value)
{
        setenv(name, value ? value : "", 1);
}

/*
 * Spawn CGI script, forward CGI's stdin/out <=> network
 *
 * Environment variables are set up and the script is invoked with pipes
 * for stdin/stdout.  If a POST is being done the script is fed the POST
 * data in addition to setting the QUERY_STRING variable (for GETs or POSTs).
 *
 * Parameters:
 * const char *url              The requested URL (with leading /).
 * int post_len                 Length of the POST body.
 * const char *cookie           For set HTTP_COOKIE.
 * const char *content_type     For set CONTENT_TYPE.
 */
static void send_cgi_and_exit(
                const char *url,
                const char *request,
                int post_len,
                const char *cookie,
                const char *content_type) NORETURN;
static void send_cgi_and_exit(
                const char *url,
                const char *request,
                int post_len,
                const char *cookie,
                const char *content_type)
{
        struct fd_pair fromCgi;  /* CGI -> httpd pipe */
        struct fd_pair toCgi;    /* httpd -> CGI pipe */
        char *script;
        int pid;

        /* Make a copy. NB: caller guarantees:
         * url[0] == '/', url[1] != '/' */
        url = xstrdup(url);

        /*
         * We are mucking with environment _first_ and then vfork/exec,
         * this allows us to use vfork safely. Parent doesn't care about
         * these environment changes anyway.
         */

        /* Check for [dirs/]script.cgi/PATH_INFO */
        script = (char*)url;
        while ((script = strchr(script + 1, '/')) != NULL) {
                *script = '\0';
                if (!is_directory(url + 1, 1, NULL)) {
                        /* not directory, found script.cgi/PATH_INFO */
                        *script = '/';
                        break;
                }
                *script = '/'; /* is directory, find next '/' */
        }
        setenv1("PATH_INFO", script);   /* set to /PATH_INFO or "" */
        setenv1("REQUEST_METHOD", request);
        if (g_query) {
                putenv(xasprintf("%s=%s?%s", "REQUEST_URI", url, g_query));
        } else {
                setenv1("REQUEST_URI", url);
        }
        if (script != NULL)
                *script = '\0';         /* cut off /PATH_INFO */

        /* SCRIPT_FILENAME is required by PHP in CGI mode */
        if (home_httpd[0] == '/') {
                char *fullpath = concat_path_file(home_httpd, url);
                setenv1("SCRIPT_FILENAME", fullpath);
        }
        /* set SCRIPT_NAME as full path: /cgi-bin/dirs/script.cgi */
        setenv1("SCRIPT_NAME", url);
        /* http://hoohoo.ncsa.uiuc.edu/cgi/env.html:
         * QUERY_STRING: The information which follows the ? in the URL
         * which referenced this script. This is the query information.
         * It should not be decoded in any fashion. This variable
         * should always be set when there is query information,
         * regardless of command line decoding. */
        /* (Older versions of bbox seem to do some decoding) */
        setenv1("QUERY_STRING", g_query);
        putenv((char*)"SERVER_SOFTWARE=busybox httpd/"BB_VER);
        putenv((char*)"SERVER_PROTOCOL=HTTP/1.0");
        putenv((char*)"GATEWAY_INTERFACE=CGI/1.1");
        /* Having _separate_ variables for IP and port defeats
         * the purpose of having socket abstraction. Which "port"
         * are you using on Unix domain socket?
         * IOW - REMOTE_PEER="1.2.3.4:56" makes much more sense.
         * Oh well... */
        {
                char *p = rmt_ip_str ? rmt_ip_str : (char*)"";
                char *cp = strrchr(p, ':');
                if (ENABLE_FEATURE_IPV6 && cp && strchr(cp, ']'))
                        cp = NULL;
                if (cp) *cp = '\0'; /* delete :PORT */
                setenv1("REMOTE_ADDR", p);
                if (cp) {
                        *cp = ':';
#if ENABLE_FEATURE_HTTPD_SET_REMOTE_PORT_TO_ENV
                        setenv1("REMOTE_PORT", cp + 1);
#endif
                }
        }
        setenv1("HTTP_USER_AGENT", user_agent);
        if (http_accept)
                setenv1("HTTP_ACCEPT", http_accept);
        if (http_accept_language)
                setenv1("HTTP_ACCEPT_LANGUAGE", http_accept_language);
        if (post_len)
                putenv(xasprintf("CONTENT_LENGTH=%d", post_len));
        if (cookie)
                setenv1("HTTP_COOKIE", cookie);
        if (content_type)
                setenv1("CONTENT_TYPE", content_type);
#if ENABLE_FEATURE_HTTPD_BASIC_AUTH
        if (remoteuser) {
                setenv1("REMOTE_USER", remoteuser);
                putenv((char*)"AUTH_TYPE=Basic");
        }
#endif
        if (referer)
                setenv1("HTTP_REFERER", referer);
        setenv1("HTTP_HOST", host); /* set to "" if NULL */
        /* setenv1("SERVER_NAME", safe_gethostname()); - don't do this,
         * just run "env SERVER_NAME=xyz httpd ..." instead */

        xpiped_pair(fromCgi);
        xpiped_pair(toCgi);

        pid = vfork();
        if (pid < 0) {
                /* TODO: log perror? */
                log_and_exit();
        }

        if (!pid) {
                /* Child process */
                char *argv[3];

                xfunc_error_retval = 242;

                /* NB: close _first_, then move fds! */
                close(toCgi.wr);
                close(fromCgi.rd);
                xmove_fd(toCgi.rd, 0);  /* replace stdin with the pipe */
                xmove_fd(fromCgi.wr, 1);  /* replace stdout with the pipe */
                /* User seeing stderr output can be a security problem.
                 * If CGI really wants that, it can always do dup itself. */
                /* dup2(1, 2); */

                /* Chdiring to script's dir */
                script = strrchr(url, '/');
                if (script != url) { /* paranoia */
                        *script = '\0';
                        if (chdir(url + 1) != 0) {
                                bb_perror_msg("chdir(%s)", url + 1);
                                goto error_execing_cgi;
                        }
                        // not needed: *script = '/';
                }
                script++;

                /* set argv[0] to name without path */
                argv[0] = script;
                argv[1] = NULL;

#if ENABLE_FEATURE_HTTPD_CONFIG_WITH_SCRIPT_INTERPR
                {
                        char *suffix = strrchr(script, '.');

                        if (suffix) {
                                Htaccess *cur;
                                for (cur = script_i; cur; cur = cur->next) {
                                        if (strcmp(cur->before_colon + 1, suffix) == 0) {
                                                /* found interpreter name */
                                                argv[0] = cur->after_colon;
                                                argv[1] = script;
                                                argv[2] = NULL;
                                                break;
                                        }
                                }
                        }
                }
#endif
                /* restore default signal dispositions for CGI process */
                bb_signals(0
                        | (1 << SIGCHLD)
                        | (1 << SIGPIPE)
                        | (1 << SIGHUP)
                        , SIG_DFL);

                /* _NOT_ execvp. We do not search PATH. argv[0] is a filename
                 * without any dir components and will only match a file
                 * in the current directory */
                execv(argv[0], argv);
                if (verbose)
                        bb_perror_msg("can't execute '%s'", argv[0]);
 error_execing_cgi:
                /* send to stdout
                 * (we are CGI here, our stdout is pumped to the net) */
                send_headers_and_exit(HTTP_NOT_FOUND);
        } /* end child */

        /* Parent process */

        /* Restore variables possibly changed by child */
        xfunc_error_retval = 0;

        /* Pump data */
        close(fromCgi.wr);
        close(toCgi.rd);
        cgi_io_loop_and_exit(fromCgi.rd, toCgi.wr, post_len);
}

#endif          /* FEATURE_HTTPD_CGI */

/*
 * Send a file response to a HTTP request, and exit
 *
 * Parameters:
 * const char *url  The requested URL (with leading /).
 * what             What to send (headers/body/both).
 */
static NOINLINE void send_file_and_exit(const char *url, int what)
{
        char *suffix;
        int fd;
        ssize_t count;

        if (content_gzip) {
                /* does <url>.gz exist? Then use it instead */
                char *gzurl = xasprintf("%s.gz", url);
                fd = open(gzurl, O_RDONLY);
                free(gzurl);
                if (fd != -1) {
                        struct stat sb;
                        fstat(fd, &sb);
                        file_size = sb.st_size;
                        last_mod = sb.st_mtime;
                } else {
                        IF_FEATURE_HTTPD_GZIP(content_gzip = 0;)
                        fd = open(url, O_RDONLY);
                }
        } else {
                fd = open(url, O_RDONLY);
        }
        if (fd < 0) {
                if (DEBUG)
                        bb_perror_msg("can't open '%s'", url);
                /* Error pages are sent by using send_file_and_exit(SEND_BODY).
                 * IOW: it is unsafe to call send_headers_and_exit
                 * if what is SEND_BODY! Can recurse! */
                if (what != SEND_BODY)
                        send_headers_and_exit(HTTP_NOT_FOUND);
                log_and_exit();
        }
        /* If you want to know about EPIPE below
         * (happens if you abort downloads from local httpd): */
        signal(SIGPIPE, SIG_IGN);

        /* If not found, default is "application/octet-stream" */
        found_mime_type = "application/octet-stream";
        suffix = strrchr(url, '.');
        if (suffix) {
                static const char suffixTable[] ALIGN1 =
                        /* Shorter suffix must be first:
                         * ".html.htm" will fail for ".htm"
                         */
                        ".txt.h.c.cc.cpp\0" "text/plain\0"
                        /* .htm line must be after .h line */
                        ".htm.html\0" "text/html\0"
                        ".jpg.jpeg\0" "image/jpeg\0"
                        ".gif\0"      "image/gif\0"
                        ".png\0"      "image/png\0"
                        /* .css line must be after .c line */
                        ".css\0"      "text/css\0"
                        ".wav\0"      "audio/wav\0"
                        ".avi\0"      "video/x-msvideo\0"
                        ".qt.mov\0"   "video/quicktime\0"
                        ".mpe.mpeg\0" "video/mpeg\0"
                        ".mid.midi\0" "audio/midi\0"
                        ".mp3\0"      "audio/mpeg\0"
#if 0  /* unpopular */
                        ".au\0"       "audio/basic\0"
                        ".pac\0"      "application/x-ns-proxy-autoconfig\0"
                        ".vrml.wrl\0" "model/vrml\0"
#endif
                        /* compiler adds another "\0" here */
                ;
                Htaccess *cur;

                /* Examine built-in table */
                const char *table = suffixTable;
                const char *table_next;
                for (; *table; table = table_next) {
                        const char *try_suffix;
                        const char *mime_type;
                        mime_type  = table + strlen(table) + 1;
                        table_next = mime_type + strlen(mime_type) + 1;
                        try_suffix = strstr(table, suffix);
                        if (!try_suffix)
                                continue;
                        try_suffix += strlen(suffix);
                        if (*try_suffix == '\0' || *try_suffix == '.') {
                                found_mime_type = mime_type;
                                break;
                        }
                        /* Example: strstr(table, ".av") != NULL, but it
                         * does not match ".avi" after all and we end up here.
                         * The table is arranged so that in this case we know
                         * that it can't match anything in the following lines,
                         * and we stop the search: */
                        break;
                }
                /* ...then user's table */
                for (cur = mime_a; cur; cur = cur->next) {
                        if (strcmp(cur->before_colon, suffix) == 0) {
                                found_mime_type = cur->after_colon;
                                break;
                        }
                }
        }

        if (DEBUG)
                bb_error_msg("sending file '%s' content-type: %s",
                        url, found_mime_type);

#if ENABLE_FEATURE_HTTPD_RANGES
        if (what == SEND_BODY /* err pages and ranges don't mix */
         || content_gzip /* we are sending compressed page: can't do ranges */  ///why?
        ) {
                range_start = 0;
        }
        range_len = MAXINT(off_t);
        if (range_start) {
                if (!range_end) {
                        range_end = file_size - 1;
                }
                if (range_end < range_start
                 || lseek(fd, range_start, SEEK_SET) != range_start
                ) {
                        lseek(fd, 0, SEEK_SET);
                        range_start = 0;
                } else {
                        range_len = range_end - range_start + 1;
                        send_headers(HTTP_PARTIAL_CONTENT);
                        what = SEND_BODY;
                }
        }
#endif
        if (what & SEND_HEADERS)
                send_headers(HTTP_OK);
#if ENABLE_FEATURE_HTTPD_USE_SENDFILE
        {
                off_t offset = range_start;
                while (1) {
                        /* sz is rounded down to 64k */
                        ssize_t sz = MAXINT(ssize_t) - 0xffff;
                        IF_FEATURE_HTTPD_RANGES(if (sz > range_len) sz = range_len;)
                        count = sendfile(STDOUT_FILENO, fd, &offset, sz);
                        if (count < 0) {
                                if (offset == range_start)
                                        break; /* fall back to read/write loop */
                                goto fin;
                        }
                        IF_FEATURE_HTTPD_RANGES(range_len -= sz;)
                        if (count == 0 || range_len == 0)
                                log_and_exit();
                }
        }
#endif
        while ((count = safe_read(fd, iobuf, IOBUF_SIZE)) > 0) {
                ssize_t n;
                IF_FEATURE_HTTPD_RANGES(if (count > range_len) count = range_len;)
                n = full_write(STDOUT_FILENO, iobuf, count);
                if (count != n)
                        break;
                IF_FEATURE_HTTPD_RANGES(range_len -= count;)
                if (range_len == 0)
                        break;
        }
        if (count < 0) {
 IF_FEATURE_HTTPD_USE_SENDFILE(fin:)
                if (verbose > 1)
                        bb_perror_msg("error");
        }
        log_and_exit();
}

static int checkPermIP(void)
{
        Htaccess_IP *cur;

        for (cur = ip_a_d; cur; cur = cur->next) {
#if DEBUG
                fprintf(stderr,
                        "checkPermIP: '%s' ? '%u.%u.%u.%u/%u.%u.%u.%u'\n",
                        rmt_ip_str,
                        (unsigned char)(cur->ip >> 24),
                        (unsigned char)(cur->ip >> 16),
                        (unsigned char)(cur->ip >> 8),
                        (unsigned char)(cur->ip),
                        (unsigned char)(cur->mask >> 24),
                        (unsigned char)(cur->mask >> 16),
                        (unsigned char)(cur->mask >> 8),
                        (unsigned char)(cur->mask)
                );
#endif
                if ((rmt_ip & cur->mask) == cur->ip)
                        return (cur->allow_deny == 'A'); /* A -> 1 */
        }

        return !flg_deny_all; /* depends on whether we saw "D:*" */
}

#if ENABLE_FEATURE_HTTPD_BASIC_AUTH
/*
 * Config file entries are of the form "/<path>:<user>:<passwd>".
 * If config file has no prefix match for path, access is allowed.
 *
 * path                 The file path
 * user_and_passwd      "user:passwd" to validate
 *
 * Returns 1 if user_and_passwd is OK.
 */
static int check_user_passwd(const char *path, const char *user_and_passwd)
{
        Htaccess *cur;
        const char *prev = NULL;

        for (cur = g_auth; cur; cur = cur->next) {
                const char *dir_prefix;
                size_t len;

                dir_prefix = cur->before_colon;

                /* WHY? */
                /* If already saw a match, don't accept other different matches */
                if (prev && strcmp(prev, dir_prefix) != 0)
                        continue;

                if (DEBUG)
                        fprintf(stderr, "checkPerm: '%s' ? '%s'\n", dir_prefix, user_and_passwd);

                /* If it's not a prefix match, continue searching */
                len = strlen(dir_prefix);
                if (len != 1 /* dir_prefix "/" matches all, don't need to check */
                 && (strncmp(dir_prefix, path, len) != 0
                    || (path[len] != '/' && path[len] != '\0'))
                ) {
                        continue;
                }

                /* Path match found */
                prev = dir_prefix;

                if (ENABLE_FEATURE_HTTPD_AUTH_MD5) {
                        char *md5_passwd;

                        md5_passwd = strchr(cur->after_colon, ':');
                        if (md5_passwd && md5_passwd[1] == '$' && md5_passwd[2] == '1'
                         && md5_passwd[3] == '$' && md5_passwd[4]
                        ) {
                                char *encrypted;
                                int r, user_len_p1;

                                md5_passwd++;
                                user_len_p1 = md5_passwd - cur->after_colon;
                                /* comparing "user:" */
                                if (strncmp(cur->after_colon, user_and_passwd, user_len_p1) != 0) {
                                        continue;
                                }

                                encrypted = pw_encrypt(
                                        user_and_passwd + user_len_p1 /* cleartext pwd from user */,
                                        md5_passwd /*salt */, 1 /* cleanup */);
                                r = strcmp(encrypted, md5_passwd);
                                free(encrypted);
                                if (r == 0)
                                        goto set_remoteuser_var; /* Ok */
                                continue;
                        }
                }

                /* Comparing plaintext "user:pass" in one go */
                if (strcmp(cur->after_colon, user_and_passwd) == 0) {
 set_remoteuser_var:
                        remoteuser = xstrndup(user_and_passwd,
                                        strchrnul(user_and_passwd, ':') - user_and_passwd);
                        return 1; /* Ok */
                }
        } /* for */

        /* 0(bad) if prev is set: matches were found but passwd was wrong */
        return (prev == NULL);
}
#endif  /* FEATURE_HTTPD_BASIC_AUTH */

#if ENABLE_FEATURE_HTTPD_PROXY
static Htaccess_Proxy *find_proxy_entry(const char *url)
{
        Htaccess_Proxy *p;
        for (p = proxy; p; p = p->next) {
                if (strncmp(url, p->url_from, strlen(p->url_from)) == 0)
                        return p;
        }
        return NULL;
}
#endif

/*
 * Handle timeouts
 */
static void send_REQUEST_TIMEOUT_and_exit(int sig) NORETURN;
static void send_REQUEST_TIMEOUT_and_exit(int sig UNUSED_PARAM)
{
        send_headers_and_exit(HTTP_REQUEST_TIMEOUT);
}

/*
 * Handle an incoming http request and exit.
 */
static void handle_incoming_and_exit(const len_and_sockaddr *fromAddr) NORETURN;
static void handle_incoming_and_exit(const len_and_sockaddr *fromAddr)
{
        static const char request_GET[] ALIGN1 = "GET";
        struct stat sb;
        char *urlcopy;
        char *urlp;
        char *tptr;
#if ENABLE_FEATURE_HTTPD_CGI
        static const char request_HEAD[] ALIGN1 = "HEAD";
        const char *prequest;
        char *cookie = NULL;
        char *content_type = NULL;
        unsigned long length = 0;
#elif ENABLE_FEATURE_HTTPD_PROXY
#define prequest request_GET
        unsigned long length = 0;
#endif
#if ENABLE_FEATURE_HTTPD_BASIC_AUTH
        smallint authorized = -1;
#endif
        smallint ip_allowed;
        char http_major_version;
#if ENABLE_FEATURE_HTTPD_PROXY
        char http_minor_version;
        char *header_buf = header_buf; /* for gcc */
        char *header_ptr = header_ptr;
        Htaccess_Proxy *proxy_entry;
#endif

        /* Allocation of iobuf is postponed until now
         * (IOW, server process doesn't need to waste 8k) */
        iobuf = xmalloc(IOBUF_SIZE);

        rmt_ip = 0;
        if (fromAddr->u.sa.sa_family == AF_INET) {
                rmt_ip = ntohl(fromAddr->u.sin.sin_addr.s_addr);
        }
#if ENABLE_FEATURE_IPV6
        if (fromAddr->u.sa.sa_family == AF_INET6
         && fromAddr->u.sin6.sin6_addr.s6_addr32[0] == 0
         && fromAddr->u.sin6.sin6_addr.s6_addr32[1] == 0
         && ntohl(fromAddr->u.sin6.sin6_addr.s6_addr32[2]) == 0xffff)
                rmt_ip = ntohl(fromAddr->u.sin6.sin6_addr.s6_addr32[3]);
#endif
        if (ENABLE_FEATURE_HTTPD_CGI || DEBUG || verbose) {
                /* NB: can be NULL (user runs httpd -i by hand?) */
                rmt_ip_str = xmalloc_sockaddr2dotted(&fromAddr->u.sa);
        }
        if (verbose) {
                /* this trick makes -v logging much simpler */
                if (rmt_ip_str)
                        applet_name = rmt_ip_str;
                if (verbose > 2)
                        bb_error_msg("connected");
        }

        /* Install timeout handler. get_line() needs it. */
        signal(SIGALRM, send_REQUEST_TIMEOUT_and_exit);

        if (!get_line()) /* EOF or error or empty line */
                send_headers_and_exit(HTTP_BAD_REQUEST);

        /* Determine type of request (GET/POST) */
        urlp = strpbrk(iobuf, " \t");
        if (urlp == NULL)
                send_headers_and_exit(HTTP_BAD_REQUEST);
        *urlp++ = '\0';
#if ENABLE_FEATURE_HTTPD_CGI
        prequest = request_GET;
        if (strcasecmp(iobuf, prequest) != 0) {
                prequest = request_HEAD;
                if (strcasecmp(iobuf, prequest) != 0) {
                        prequest = "POST";
                        if (strcasecmp(iobuf, prequest) != 0)
                                send_headers_and_exit(HTTP_NOT_IMPLEMENTED);
                }
        }
#else
        if (strcasecmp(iobuf, request_GET) != 0)
                send_headers_and_exit(HTTP_NOT_IMPLEMENTED);
#endif
        urlp = skip_whitespace(urlp);
        if (urlp[0] != '/')
                send_headers_and_exit(HTTP_BAD_REQUEST);

        /* Find end of URL and parse HTTP version, if any */
        http_major_version = '0';
        IF_FEATURE_HTTPD_PROXY(http_minor_version = '0';)
        tptr = strchrnul(urlp, ' ');
        /* Is it " HTTP/"? */
        if (tptr[0] && strncmp(tptr + 1, HTTP_200, 5) == 0) {
                http_major_version = tptr[6];
                IF_FEATURE_HTTPD_PROXY(http_minor_version = tptr[8];)
        }
        *tptr = '\0';

        /* Copy URL from after "GET "/"POST " to stack-allocated char[] */
        urlcopy = alloca((tptr - urlp) + 2 + strlen(index_page));
        /*if (urlcopy == NULL)
         *      send_headers_and_exit(HTTP_INTERNAL_SERVER_ERROR);*/
        strcpy(urlcopy, urlp);
        /* NB: urlcopy ptr is never changed after this */

        /* Extract url args if present */
        g_query = NULL;
        tptr = strchr(urlcopy, '?');
        if (tptr) {
                *tptr++ = '\0';
                g_query = tptr;
        }

        /* Decode URL escape sequences */
        tptr = decodeString(urlcopy, 0);
        if (tptr == NULL)
                send_headers_and_exit(HTTP_BAD_REQUEST);
        if (tptr == urlcopy + 1) {
                /* '/' or NUL is encoded */
                send_headers_and_exit(HTTP_NOT_FOUND);
        }

        /* Canonicalize path */
        /* Algorithm stolen from libbb bb_simplify_path(),
         * but don't strdup, retain trailing slash, protect root */
        urlp = tptr = urlcopy;
        do {
                if (*urlp == '/') {
                        /* skip duplicate (or initial) slash */
                        if (*tptr == '/') {
                                continue;
                        }
                        if (*tptr == '.') {
                                /* skip extra "/./" */
                                if (tptr[1] == '/' || !tptr[1]) {
                                        continue;
                                }
                                /* "..": be careful */
                                if (tptr[1] == '.' && (tptr[2] == '/' || !tptr[2])) {
                                        ++tptr;
                                        if (urlp == urlcopy) /* protect root */
                                                send_headers_and_exit(HTTP_BAD_REQUEST);
                                        while (*--urlp != '/') /* omit previous dir */;
                                                continue;
                                }
                        }
                }
                *++urlp = *tptr;
        } while (*++tptr);
        *++urlp = '\0';       /* terminate after last character */

        /* If URL is a directory, add '/' */
        if (urlp[-1] != '/') {
                if (is_directory(urlcopy + 1, 1, NULL)) {
                        found_moved_temporarily = urlcopy;
                }
        }

        /* Log it */
        if (verbose > 1)
                bb_error_msg("url:%s", urlcopy);

        tptr = urlcopy;
        ip_allowed = checkPermIP();
        while (ip_allowed && (tptr = strchr(tptr + 1, '/')) != NULL) {
                /* have path1/path2 */
                *tptr = '\0';
                if (is_directory(urlcopy + 1, 1, NULL)) {
                        /* may have subdir config */
                        parse_conf(urlcopy + 1, SUBDIR_PARSE);
                        ip_allowed = checkPermIP();
                }
                *tptr = '/';
        }

#if ENABLE_FEATURE_HTTPD_PROXY
        proxy_entry = find_proxy_entry(urlcopy);
        if (proxy_entry)
                header_buf = header_ptr = xmalloc(IOBUF_SIZE);
#endif

        if (http_major_version >= '0') {
                /* Request was with "... HTTP/nXXX", and n >= 0 */

                /* Read until blank line */
                while (1) {
                        if (!get_line())
                                break; /* EOF or error or empty line */
                        if (DEBUG)
                                bb_error_msg("header: '%s'", iobuf);

#if ENABLE_FEATURE_HTTPD_PROXY
                        /* We need 2 more bytes for yet another "\r\n" -

                         * see near fdprintf(proxy_fd...) further below */
                        if (proxy_entry && (header_ptr - header_buf) < IOBUF_SIZE - 2) {
                                int len = strlen(iobuf);
                                if (len > IOBUF_SIZE - (header_ptr - header_buf) - 4)
                                        len = IOBUF_SIZE - (header_ptr - header_buf) - 4;
                                memcpy(header_ptr, iobuf, len);
                                header_ptr += len;
                                header_ptr[0] = '\r';
                                header_ptr[1] = '\n';
                                header_ptr += 2;
                        }
#endif

#if ENABLE_FEATURE_HTTPD_CGI || ENABLE_FEATURE_HTTPD_PROXY
                        /* Try and do our best to parse more lines */
                        if ((STRNCASECMP(iobuf, "Content-length:") == 0)) {
                                /* extra read only for POST */
                                if (prequest != request_GET
# if ENABLE_FEATURE_HTTPD_CGI
                                 && prequest != request_HEAD
# endif
                                ) {
                                        tptr = skip_whitespace(iobuf + sizeof("Content-length:") - 1);
                                        if (!tptr[0])
                                                send_headers_and_exit(HTTP_BAD_REQUEST);
                                        /* not using strtoul: it ignores leading minus! */
                                        length = bb_strtou(tptr, NULL, 10);
                                        /* length is "ulong", but we need to pass it to int later */
                                        if (errno || length > INT_MAX)
                                                send_headers_and_exit(HTTP_BAD_REQUEST);
                                }
                        }
#endif
#if ENABLE_FEATURE_HTTPD_CGI
                        else if (STRNCASECMP(iobuf, "Cookie:") == 0) {
                                cookie = xstrdup(skip_whitespace(iobuf + sizeof("Cookie:")-1));
                        } else if (STRNCASECMP(iobuf, "Content-Type:") == 0) {
                                content_type = xstrdup(skip_whitespace(iobuf + sizeof("Content-Type:")-1));
                        } else if (STRNCASECMP(iobuf, "Referer:") == 0) {
                                referer = xstrdup(skip_whitespace(iobuf + sizeof("Referer:")-1));
                        } else if (STRNCASECMP(iobuf, "User-Agent:") == 0) {
                                user_agent = xstrdup(skip_whitespace(iobuf + sizeof("User-Agent:")-1));
                        } else if (STRNCASECMP(iobuf, "Host:") == 0) {
                                host = xstrdup(skip_whitespace(iobuf + sizeof("Host:")-1));
                        } else if (STRNCASECMP(iobuf, "Accept:") == 0) {
                                http_accept = xstrdup(skip_whitespace(iobuf + sizeof("Accept:")-1));
                        } else if (STRNCASECMP(iobuf, "Accept-Language:") == 0) {
                                http_accept_language = xstrdup(skip_whitespace(iobuf + sizeof("Accept-Language:")-1));
                        }
#endif
#if ENABLE_FEATURE_HTTPD_BASIC_AUTH
                        if (STRNCASECMP(iobuf, "Authorization:") == 0) {
                                /* We only allow Basic credentials.
                                 * It shows up as "Authorization: Basic <user>:<passwd>" where
                                 * "<user>:<passwd>" is base64 encoded.
                                 */
                                tptr = skip_whitespace(iobuf + sizeof("Authorization:")-1);
                                if (STRNCASECMP(tptr, "Basic") != 0)
                                        continue;
                                tptr += sizeof("Basic")-1;
                                /* decodeBase64() skips whitespace itself */
                                decodeBase64(tptr);
                                authorized = check_user_passwd(urlcopy, tptr);
                        }
#endif
#if ENABLE_FEATURE_HTTPD_RANGES
                        if (STRNCASECMP(iobuf, "Range:") == 0) {
                                /* We know only bytes=NNN-[MMM] */
                                char *s = skip_whitespace(iobuf + sizeof("Range:")-1);
                                if (strncmp(s, "bytes=", 6) == 0) {
                                        s += sizeof("bytes=")-1;
                                        range_start = BB_STRTOOFF(s, &s, 10);
                                        if (s[0] != '-' || range_start < 0) {
                                                range_start = 0;
                                        } else if (s[1]) {
                                                range_end = BB_STRTOOFF(s+1, NULL, 10);
                                                if (errno || range_end < range_start)
                                                        range_start = 0;
                                        }
                                }
                        }
#endif
#if ENABLE_FEATURE_HTTPD_GZIP
                        if (STRNCASECMP(iobuf, "Accept-Encoding:") == 0) {
                                /* Note: we do not support "gzip;q=0"
                                 * method of _disabling_ gzip
                                 * delivery. No one uses that, though */
                                const char *s = strstr(iobuf, "gzip");
                                if (s) {
                                        // want more thorough checks?
                                        //if (s[-1] == ' '
                                        // || s[-1] == ','
                                        // || s[-1] == ':'
                                        //) {
                                                content_gzip = 1;
                                        //}
                                }
                        }
#endif
                } /* while extra header reading */
        }

        /* We are done reading headers, disable peer timeout */
        alarm(0);

        if (strcmp(bb_basename(urlcopy), HTTPD_CONF) == 0 || !ip_allowed) {
                /* protect listing [/path]/httpd.conf or IP deny */
                send_headers_and_exit(HTTP_FORBIDDEN);
        }

#if ENABLE_FEATURE_HTTPD_BASIC_AUTH
        /* Case: no "Authorization:" was seen, but page does require passwd.
         * Check that with dummy user:pass */
        if (authorized < 0)
                authorized = check_user_passwd(urlcopy, ":");
        if (!authorized)
                send_headers_and_exit(HTTP_UNAUTHORIZED);
#endif

        if (found_moved_temporarily) {
                send_headers_and_exit(HTTP_MOVED_TEMPORARILY);
        }

#if ENABLE_FEATURE_HTTPD_PROXY
        if (proxy_entry != NULL) {
                int proxy_fd;
                len_and_sockaddr *lsa;

                proxy_fd = socket(AF_INET, SOCK_STREAM, 0);
                if (proxy_fd < 0)
                        send_headers_and_exit(HTTP_INTERNAL_SERVER_ERROR);
                lsa = host2sockaddr(proxy_entry->host_port, 80);
                if (lsa == NULL)
                        send_headers_and_exit(HTTP_INTERNAL_SERVER_ERROR);
                if (connect(proxy_fd, &lsa->u.sa, lsa->len) < 0)
                        send_headers_and_exit(HTTP_INTERNAL_SERVER_ERROR);
                fdprintf(proxy_fd, "%s %s%s%s%s HTTP/%c.%c\r\n",
                                prequest, /* GET or POST */
                                proxy_entry->url_to, /* url part 1 */
                                urlcopy + strlen(proxy_entry->url_from), /* url part 2 */
                                (g_query ? "?" : ""), /* "?" (maybe) */
                                (g_query ? g_query : ""), /* query string (maybe) */
                                http_major_version, http_minor_version);
                header_ptr[0] = '\r';
                header_ptr[1] = '\n';
                header_ptr += 2;
                write(proxy_fd, header_buf, header_ptr - header_buf);
                free(header_buf); /* on the order of 8k, free it */
                cgi_io_loop_and_exit(proxy_fd, proxy_fd, length);
        }
#endif

        tptr = urlcopy + 1;      /* skip first '/' */

#if ENABLE_FEATURE_HTTPD_CGI
        if (strncmp(tptr, "cgi-bin/", 8) == 0) {
                if (tptr[8] == '\0') {
                        /* protect listing "cgi-bin/" */
                        send_headers_and_exit(HTTP_FORBIDDEN);
                }
                send_cgi_and_exit(urlcopy, prequest, length, cookie, content_type);
        }
#endif

        if (urlp[-1] == '/')
                strcpy(urlp, index_page);
        if (stat(tptr, &sb) == 0) {
#if ENABLE_FEATURE_HTTPD_CONFIG_WITH_SCRIPT_INTERPR
                char *suffix = strrchr(tptr, '.');
                if (suffix) {
                        Htaccess *cur;
                        for (cur = script_i; cur; cur = cur->next) {
                                if (strcmp(cur->before_colon + 1, suffix) == 0) {
                                        send_cgi_and_exit(urlcopy, prequest, length, cookie, content_type);
                                }
                        }
                }
#endif
                file_size = sb.st_size;
                last_mod = sb.st_mtime;
        }
#if ENABLE_FEATURE_HTTPD_CGI
        else if (urlp[-1] == '/') {
                /* It's a dir URL and there is no index.html
                 * Try cgi-bin/index.cgi */
                if (access("/cgi-bin/index.cgi"+1, X_OK) == 0) {
                        urlp[0] = '\0';
                        g_query = urlcopy;
                        send_cgi_and_exit("/cgi-bin/index.cgi", prequest, length, cookie, content_type);
                }
        }
        /* else fall through to send_file, it errors out if open fails: */

        if (prequest != request_GET && prequest != request_HEAD) {
                /* POST for files does not make sense */
                send_headers_and_exit(HTTP_NOT_IMPLEMENTED);
        }
        send_file_and_exit(tptr,
                (prequest != request_HEAD ? SEND_HEADERS_AND_BODY : SEND_HEADERS)
        );
#else
        send_file_and_exit(tptr, SEND_HEADERS_AND_BODY);
#endif
}

/*
 * The main http server function.
 * Given a socket, listen for new connections and farm out
 * the processing as a [v]forked process.
 * Never returns.
 */
#if BB_MMU
static void mini_httpd(int server_socket) NORETURN;
static void mini_httpd(int server_socket)
{
        /* NB: it's best to not use xfuncs in this loop before fork().
         * Otherwise server may die on transient errors (temporary
         * out-of-memory condition, etc), which is Bad(tm).
         * Try to do any dangerous calls after fork.
         */
        while (1) {
                int n;
                len_and_sockaddr fromAddr;

                /* Wait for connections... */
                fromAddr.len = LSA_SIZEOF_SA;
                n = accept(server_socket, &fromAddr.u.sa, &fromAddr.len);
                if (n < 0)
                        continue;

                /* set the KEEPALIVE option to cull dead connections */
                setsockopt(n, SOL_SOCKET, SO_KEEPALIVE, &const_int_1, sizeof(const_int_1));

                if (fork() == 0) {
                        /* child */
                        /* Do not reload config on HUP */
                        signal(SIGHUP, SIG_IGN);
                        close(server_socket);
                        xmove_fd(n, 0);
                        xdup2(0, 1);

                        handle_incoming_and_exit(&fromAddr);
                }
                /* parent, or fork failed */
                close(n);
        } /* while (1) */
        /* never reached */
}
#else
static void mini_httpd_nommu(int server_socket, int argc, char **argv) NORETURN;
static void mini_httpd_nommu(int server_socket, int argc, char **argv)
{
        char *argv_copy[argc + 2];

        argv_copy[0] = argv[0];
        argv_copy[1] = (char*)"-i";
        memcpy(&argv_copy[2], &argv[1], argc * sizeof(argv[0]));

        /* NB: it's best to not use xfuncs in this loop before vfork().
         * Otherwise server may die on transient errors (temporary
         * out-of-memory condition, etc), which is Bad(tm).
         * Try to do any dangerous calls after fork.
         */
        while (1) {
                int n;
                len_and_sockaddr fromAddr;

                /* Wait for connections... */
                fromAddr.len = LSA_SIZEOF_SA;
                n = accept(server_socket, &fromAddr.u.sa, &fromAddr.len);
                if (n < 0)
                        continue;

                /* set the KEEPALIVE option to cull dead connections */
                setsockopt(n, SOL_SOCKET, SO_KEEPALIVE, &const_int_1, sizeof(const_int_1));

                if (vfork() == 0) {
                        /* child */
                        /* Do not reload config on HUP */
                        signal(SIGHUP, SIG_IGN);
                        close(server_socket);
                        xmove_fd(n, 0);
                        xdup2(0, 1);

                        /* Run a copy of ourself in inetd mode */
                        re_exec(argv_copy);
                }
                /* parent, or vfork failed */
                close(n);
        } /* while (1) */
        /* never reached */
}
#endif

/*
 * Process a HTTP connection on stdin/out.
 * Never returns.
 */
static void mini_httpd_inetd(void) NORETURN;
static void mini_httpd_inetd(void)
{
        len_and_sockaddr fromAddr;

        memset(&fromAddr, 0, sizeof(fromAddr));
        fromAddr.len = LSA_SIZEOF_SA;
        /* NB: can fail if user runs it by hand and types in http cmds */
        getpeername(0, &fromAddr.u.sa, &fromAddr.len);
        handle_incoming_and_exit(&fromAddr);
}

static void sighup_handler(int sig UNUSED_PARAM)
{
        parse_conf(DEFAULT_PATH_HTTPD_CONF, SIGNALED_PARSE);
}

enum {
        c_opt_config_file = 0,
        d_opt_decode_url,
        h_opt_home_httpd,
        IF_FEATURE_HTTPD_ENCODE_URL_STR(e_opt_encode_url,)
        IF_FEATURE_HTTPD_BASIC_AUTH(    r_opt_realm     ,)
        IF_FEATURE_HTTPD_AUTH_MD5(      m_opt_md5       ,)
        IF_FEATURE_HTTPD_SETUID(        u_opt_setuid    ,)
        p_opt_port      ,
        p_opt_inetd     ,
        p_opt_foreground,
        p_opt_verbose   ,
        OPT_CONFIG_FILE = 1 << c_opt_config_file,
        OPT_DECODE_URL  = 1 << d_opt_decode_url,
        OPT_HOME_HTTPD  = 1 << h_opt_home_httpd,
        OPT_ENCODE_URL  = IF_FEATURE_HTTPD_ENCODE_URL_STR((1 << e_opt_encode_url)) + 0,
        OPT_REALM       = IF_FEATURE_HTTPD_BASIC_AUTH(    (1 << r_opt_realm     )) + 0,
        OPT_MD5         = IF_FEATURE_HTTPD_AUTH_MD5(      (1 << m_opt_md5       )) + 0,
        OPT_SETUID      = IF_FEATURE_HTTPD_SETUID(        (1 << u_opt_setuid    )) + 0,
        OPT_PORT        = 1 << p_opt_port,
        OPT_INETD       = 1 << p_opt_inetd,
        OPT_FOREGROUND  = 1 << p_opt_foreground,
        OPT_VERBOSE     = 1 << p_opt_verbose,
};


int httpd_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
int httpd_main(int argc UNUSED_PARAM, char **argv)
{
        int server_socket = server_socket; /* for gcc */
        unsigned opt;
        char *url_for_decode;
        IF_FEATURE_HTTPD_ENCODE_URL_STR(const char *url_for_encode;)
        IF_FEATURE_HTTPD_SETUID(const char *s_ugid = NULL;)
        IF_FEATURE_HTTPD_SETUID(struct bb_uidgid_t ugid;)
        IF_FEATURE_HTTPD_AUTH_MD5(const char *pass;)

        INIT_G();

#if ENABLE_LOCALE_SUPPORT
        /* Undo busybox.c: we want to speak English in http (dates etc) */
        setlocale(LC_TIME, "C");
#endif

        home_httpd = xrealloc_getcwd_or_warn(NULL);
        /* -v counts, -i implies -f */
        opt_complementary = "vv:if";
        /* We do not "absolutize" path given by -h (home) opt.
         * If user gives relative path in -h,
         * $SCRIPT_FILENAME will not be set. */
        opt = getopt32(argv, "c:d:h:"
                        IF_FEATURE_HTTPD_ENCODE_URL_STR("e:")
                        IF_FEATURE_HTTPD_BASIC_AUTH("r:")
                        IF_FEATURE_HTTPD_AUTH_MD5("m:")
                        IF_FEATURE_HTTPD_SETUID("u:")
                        "p:ifv",
                        &opt_c_configFile, &url_for_decode, &home_httpd
                        IF_FEATURE_HTTPD_ENCODE_URL_STR(, &url_for_encode)
                        IF_FEATURE_HTTPD_BASIC_AUTH(, &g_realm)
                        IF_FEATURE_HTTPD_AUTH_MD5(, &pass)
                        IF_FEATURE_HTTPD_SETUID(, &s_ugid)
                        , &bind_addr_or_port
                        , &verbose
                );
        if (opt & OPT_DECODE_URL) {
                fputs(decodeString(url_for_decode, 1), stdout);
                return 0;
        }
#if ENABLE_FEATURE_HTTPD_ENCODE_URL_STR
        if (opt & OPT_ENCODE_URL) {
                fputs(encodeString(url_for_encode), stdout);
                return 0;
        }
#endif
#if ENABLE_FEATURE_HTTPD_AUTH_MD5
        if (opt & OPT_MD5) {
                char salt[sizeof("$1$XXXXXXXX")];
                salt[0] = '$';
                salt[1] = '1';
                salt[2] = '$';
                crypt_make_salt(salt + 3, 4, 0);
                puts(pw_encrypt(pass, salt, 1));
                return 0;
        }
#endif
#if ENABLE_FEATURE_HTTPD_SETUID
        if (opt & OPT_SETUID) {
                xget_uidgid(&ugid, s_ugid);
        }
#endif

#if !BB_MMU
        if (!(opt & OPT_FOREGROUND)) {
                bb_daemonize_or_rexec(0, argv); /* don't change current directory */
        }
#endif

        xchdir(home_httpd);
        if (!(opt & OPT_INETD)) {
                signal(SIGCHLD, SIG_IGN);
                server_socket = openServer();
#if ENABLE_FEATURE_HTTPD_SETUID
                /* drop privileges */
                if (opt & OPT_SETUID) {
                        if (ugid.gid != (gid_t)-1) {
                                if (setgroups(1, &ugid.gid) == -1)
                                        bb_perror_msg_and_die("setgroups");
                                xsetgid(ugid.gid);
                        }
                        xsetuid(ugid.uid);
                }
#endif
        }

#if 0
        /* User can do it himself: 'env - PATH="$PATH" httpd'
         * We don't do it because we don't want to screw users
         * which want to do
         * 'env - VAR1=val1 VAR2=val2 httpd'
         * and have VAR1 and VAR2 values visible in their CGIs.
         * Besides, it is also smaller. */
        {
                char *p = getenv("PATH");
                /* env strings themself are not freed, no need to xstrdup(p): */
                clearenv();
                if (p)
                        putenv(p - 5);
//              if (!(opt & OPT_INETD))
//                      setenv_long("SERVER_PORT", ???);
        }
#endif

        parse_conf(DEFAULT_PATH_HTTPD_CONF, FIRST_PARSE);
        if (!(opt & OPT_INETD))
                signal(SIGHUP, sighup_handler);

        xfunc_error_retval = 0;
        if (opt & OPT_INETD)
                mini_httpd_inetd();
#if BB_MMU
        if (!(opt & OPT_FOREGROUND))
                bb_daemonize(0); /* don't change current directory */
        mini_httpd(server_socket); /* never returns */
#else
        mini_httpd_nommu(server_socket, argc, argv); /* never returns */
#endif
        /* return 0; */
}