release/src/router/busybox/networking/isrv_identd.c

   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
  24 enum { TIMEOUT = 20 };
  25
  26 typedef 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
  34 static 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
  50 static 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
  89 static int do_timeout(void **paramp UNUSED_PARAM)
  90 {
  91         return 1; /* terminate session */
  92 }
  93
  94 static 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
 105 int fakeidentd_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
 106 int 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 }