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