LXR busybox/networking/isrv

   1/* vi: set sw=4 ts=4: */
   2/*
   3 * Fake identd server.
   4 *
   5 * Copyright (C) 2007 Denys Vlasenko
   6 *
   7 * Licensed under GPLv2, see file LICENSE in this source tree.
   8 */
   9
  10//usage:#define fakeidentd_trivial_usage
  11//usage:       "[-fiw] [-b ADDR] [STRING]"
  12//usage:#define fakeidentd_full_usage "\n\n"
  13//usage:       "Provide fake ident (auth) service\n"
  14//usage:     "\n        -f      Run in foreground"
  15//usage:     "\n        -i      Inetd mode"
  16//usage:     "\n        -w      Inetd 'wait' mode"
  17//usage:     "\n        -b ADDR Bind to specified address"
  18//usage:     "\n        STRING  Ident answer string (default: nobody)"
  19
  20#include "libbb.h"
  21#include <syslog.h>
  22#include "isrv.h"
  23
  24enum { TIMEOUT = 20 };
  25
  26typedef struct identd_buf_t {
  27        int pos;
  28        int fd_flag;
  29        char buf[64 - 2*sizeof(int)];
  30} identd_buf_t;
  31
  32#define bogouser bb_common_bufsiz1
  33
  34static int new_peer(isrv_state_t *state, int fd)
  35{
  36        int peer;
  37        identd_buf_t *buf = xzalloc(sizeof(*buf));
  38
  39        peer = isrv_register_peer(state, buf);
  40        if (peer < 0)
  41                return 0; /* failure */
  42        if (isrv_register_fd(state, peer, fd) < 0)
  43                return peer; /* failure, unregister peer */
  44
  45        buf->fd_flag = fcntl(fd, F_GETFL) | O_NONBLOCK;
  46        isrv_want_rd(state, fd);
  47        return 0;
  48}
  49
  50static int do_rd(int fd, void **paramp)
  51{
  52        identd_buf_t *buf = *paramp;
  53        char *cur, *p;
  54        int retval = 0; /* session is ok (so far) */
  55        int sz;
  56
  57        cur = buf->buf + buf->pos;
  58
  59        if (buf->fd_flag & O_NONBLOCK)
  60                fcntl(fd, F_SETFL, buf->fd_flag);
  61        sz = safe_read(fd, cur, sizeof(buf->buf) - buf->pos);
  62
  63        if (sz < 0) {
  64                if (errno != EAGAIN)
  65                        goto term; /* terminate this session if !EAGAIN */
  66                goto ok;
  67        }
  68
  69        buf->pos += sz;
  70        buf->buf[buf->pos] = '\0';
  71        p = strpbrk(cur, "\r\n");
  72        if (p)
  73                *p = '\0';
  74        if (!p && sz && buf->pos <= (int)sizeof(buf->buf))
  75                goto ok;
  76        /* Terminate session. If we are in server mode, then
  77         * fd is still in nonblocking mode - we never block here */
  78        if (fd == 0) fd++; /* inetd mode? then write to fd 1 */
  79        fdprintf(fd, "%s : USERID : UNIX : %s\r\n", buf->buf, bogouser);
  80 term:
  81        free(buf);
  82        retval = 1; /* terminate */
  83 ok:
  84        if (buf->fd_flag & O_NONBLOCK)
  85                fcntl(fd, F_SETFL, buf->fd_flag & ~O_NONBLOCK);
  86        return retval;
  87}
  88
  89static int do_timeout(void **paramp UNUSED_PARAM)
  90{
  91        return 1; /* terminate session */
  92}
  93
  94static void inetd_mode(void)
  95{
  96        identd_buf_t *buf = xzalloc(sizeof(*buf));
  97        /* buf->pos = 0; - xzalloc did it */
  98        /* We do NOT want nonblocking I/O here! */
  99        /* buf->fd_flag = 0; - xzalloc did it */
 100        do
 101                alarm(TIMEOUT);
 102        while (do_rd(0, (void*)&buf) == 0);
 103}
 104
 105int fakeidentd_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
 106int fakeidentd_main(int argc UNUSED_PARAM, char **argv)
 107{
 108        enum {
 109                OPT_foreground = 0x1,
 110                OPT_inetd      = 0x2,
 111                OPT_inetdwait  = 0x4,
 112                OPT_fiw        = 0x7,
 113                OPT_bindaddr   = 0x8,
 114        };
 115
 116        const char *bind_address = NULL;
 117        unsigned opt;
 118        int fd;
 119
 120        opt = getopt32(argv, "fiwb:", &bind_address);
 121        strcpy(bogouser, "nobody");
 122        if (argv[optind])
 123                strncpy(bogouser, argv[optind], sizeof(bogouser));
 124
 125        /* Daemonize if no -f and no -i and no -w */
 126        if (!(opt & OPT_fiw))
 127                bb_daemonize_or_rexec(0, argv);
 128
 129        /* Where to log in inetd modes? "Classic" inetd
 130         * probably has its stderr /dev/null'ed (we need log to syslog?),
 131         * but daemontools-like utilities usually expect that children
 132         * log to stderr. I like daemontools more. Go their way.
 133         * (Or maybe we need yet another option "log to syslog") */
 134        if (!(opt & OPT_fiw) /* || (opt & OPT_syslog) */) {
 135                openlog(applet_name, LOG_PID, LOG_DAEMON);
 136                logmode = LOGMODE_SYSLOG;
 137        }
 138
 139        if (opt & OPT_inetd) {
 140                inetd_mode();
 141                return 0;
 142        }
 143
 144        /* Ignore closed connections when writing */
 145        signal(SIGPIPE, SIG_IGN);
 146
 147        fd = 0;
 148        if (!(opt & OPT_inetdwait)) {
 149                fd = create_and_bind_stream_or_die(bind_address,
 150                                bb_lookup_port("identd", "tcp", 113));
 151                xlisten(fd, 5);
 152        }
 153
 154        isrv_run(fd, new_peer, do_rd, /*do_wr:*/ NULL, do_timeout,
 155                        TIMEOUT, (opt & OPT_inetdwait) ? TIMEOUT : 0);
 156        return 0;
 157}
 158