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        char buf[64 - sizeof(int)];
  29} identd_buf_t;
  30
  31#define bogouser bb_common_bufsiz1
  32
  33static int new_peer(isrv_state_t *state, int fd)
  34{
  35        int peer;
  36        identd_buf_t *buf = xzalloc(sizeof(*buf));
  37
  38        peer = isrv_register_peer(state, buf);
  39        if (peer < 0)
  40                return 0; /* failure */
  41        if (isrv_register_fd(state, peer, fd) < 0)
  42                return peer; /* failure, unregister peer */
  43
  44        ndelay_on(fd);
  45        isrv_want_rd(state, fd);
  46        return 0;
  47}
  48
  49static int do_rd(int fd, void **paramp)
  50{
  51        identd_buf_t *buf = *paramp;
  52        char *cur, *p;
  53        int sz;
  54
  55        cur = buf->buf + buf->pos;
  56
  57        sz = safe_read(fd, cur, sizeof(buf->buf) - 1 - buf->pos);
  58
  59        if (sz < 0) {
  60                if (errno != EAGAIN)
  61                        goto term;
  62                return 0; /* "session is ok" */
  63        }
  64
  65        buf->pos += sz;
  66        buf->buf[buf->pos] = '\0';
  67        p = strpbrk(cur, "\r\n");
  68        if (p)
  69                *p = '\0';
  70        if (!p && sz)
  71                return 0;  /* "session is ok" */
  72
  73        /* Terminate session. If we are in server mode, then
  74         * fd is still in nonblocking mode - we never block here */
  75        if (fd == 0)
  76                fd++; /* inetd mode? then write to fd 1 */
  77        fdprintf(fd, "%s : USERID : UNIX : %s\r\n", buf->buf, bogouser);
  78        /*
  79         * Why bother if we are going to close fd now anyway?
  80         * if (server)
  81         *      ndelay_off(fd);
  82         */
  83 term:
  84        free(buf);
  85        return 1; /* "terminate" */
  86}
  87
  88static int do_timeout(void **paramp UNUSED_PARAM)
  89{
  90        return 1; /* terminate session */
  91}
  92
  93static void inetd_mode(void)
  94{
  95        identd_buf_t *buf = xzalloc(sizeof(*buf));
  96        /* buf->pos = 0; - xzalloc did it */
  97        do
  98                alarm(TIMEOUT);
  99                /* Note: we do NOT want nonblocking I/O here! */
 100        while (do_rd(0, (void*)&buf) == 0);
 101}
 102
 103int fakeidentd_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
 104int fakeidentd_main(int argc UNUSED_PARAM, char **argv)
 105{
 106        enum {
 107                OPT_foreground = 0x1,
 108                OPT_inetd      = 0x2,
 109                OPT_inetdwait  = 0x4,
 110                OPT_fiw        = 0x7,
 111                OPT_bindaddr   = 0x8,
 112        };
 113
 114        const char *bind_address = NULL;
 115        unsigned opt;
 116        int fd;
 117
 118        opt = getopt32(argv, "fiwb:", &bind_address);
 119        strcpy(bogouser, "nobody");
 120        if (argv[optind])
 121                strncpy(bogouser, argv[optind], sizeof(bogouser) - 1);
 122
 123        /* Daemonize if no -f and no -i and no -w */
 124        if (!(opt & OPT_fiw))
 125                bb_daemonize_or_rexec(0, argv);
 126
 127        /* Where to log in inetd modes? "Classic" inetd
 128         * probably has its stderr /dev/null'ed (we need log to syslog?),
 129         * but daemontools-like utilities usually expect that children
 130         * log to stderr. I like daemontools more. Go their way.
 131         * (Or maybe we need yet another option "log to syslog") */
 132        if (!(opt & OPT_fiw) /* || (opt & OPT_syslog) */) {
 133                openlog(applet_name, LOG_PID, LOG_DAEMON);
 134                logmode = LOGMODE_SYSLOG;
 135        }
 136
 137        if (opt & OPT_inetd) {
 138                inetd_mode();
 139                return 0;
 140        }
 141
 142        /* Ignore closed connections when writing */
 143        signal(SIGPIPE, SIG_IGN);
 144
 145        fd = 0;
 146        if (!(opt & OPT_inetdwait)) {
 147                fd = create_and_bind_stream_or_die(bind_address,
 148                                bb_lookup_port("identd", "tcp", 113));
 149                xlisten(fd, 5);
 150        }
 151
 152        isrv_run(fd, new_peer, do_rd, /*do_wr:*/ NULL, do_timeout,
 153                        TIMEOUT, (opt & OPT_inetdwait) ? TIMEOUT : 0);
 154        return 0;
 155}
 156