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//config:config FAKEIDENTD
  10//config:       bool "fakeidentd"
  11//config:       default y
  12//config:       select FEATURE_SYSLOG
  13//config:       help
  14//config:         fakeidentd listens on the ident port and returns a predefined
  15//config:         fake value on any query.
  16
  17//applet:IF_FAKEIDENTD(APPLET(fakeidentd, BB_DIR_USR_SBIN, BB_SUID_DROP))
  18
  19//kbuild:lib-$(CONFIG_FAKEIDENTD) += isrv_identd.o isrv.o
  20
  21//usage:#define fakeidentd_trivial_usage
  22//usage:       "[-fiw] [-b ADDR] [STRING]"
  23//usage:#define fakeidentd_full_usage "\n\n"
  24//usage:       "Provide fake ident (auth) service\n"
  25//usage:     "\n        -f      Run in foreground"
  26//usage:     "\n        -i      Inetd mode"
  27//usage:     "\n        -w      Inetd 'wait' mode"
  28//usage:     "\n        -b ADDR Bind to specified address"
  29//usage:     "\n        STRING  Ident answer string (default: nobody)"
  30
  31#include "libbb.h"
  32#include "common_bufsiz.h"
  33#include <syslog.h>
  34#include "isrv.h"
  35
  36enum { TIMEOUT = 20 };
  37
  38typedef struct identd_buf_t {
  39        int pos;
  40        char buf[64 - sizeof(int)];
  41} identd_buf_t;
  42
  43#define bogouser bb_common_bufsiz1
  44
  45static int new_peer(isrv_state_t *state, int fd)
  46{
  47        int peer;
  48        identd_buf_t *buf = xzalloc(sizeof(*buf));
  49
  50        peer = isrv_register_peer(state, buf);
  51        if (peer < 0)
  52                return 0; /* failure */
  53        if (isrv_register_fd(state, peer, fd) < 0)
  54                return peer; /* failure, unregister peer */
  55
  56        ndelay_on(fd);
  57        isrv_want_rd(state, fd);
  58        return 0;
  59}
  60
  61static int do_rd(int fd, void **paramp)
  62{
  63        identd_buf_t *buf = *paramp;
  64        char *cur, *p;
  65        int sz;
  66
  67        cur = buf->buf + buf->pos;
  68
  69        sz = safe_read(fd, cur, sizeof(buf->buf) - 1 - buf->pos);
  70
  71        if (sz < 0) {
  72                if (errno != EAGAIN)
  73                        goto term;
  74                return 0; /* "session is ok" */
  75        }
  76
  77        buf->pos += sz;
  78        buf->buf[buf->pos] = '\0';
  79        p = strpbrk(cur, "\r\n");
  80        if (p)
  81                *p = '\0';
  82        if (!p && sz)
  83                return 0;  /* "session is ok" */
  84
  85        /* Terminate session. If we are in server mode, then
  86         * fd is still in nonblocking mode - we never block here */
  87        if (fd == 0)
  88                fd++; /* inetd mode? then write to fd 1 */
  89        fdprintf(fd, "%s : USERID : UNIX : %s\r\n", buf->buf, bogouser);
  90        /*
  91         * Why bother if we are going to close fd now anyway?
  92         * if (server)
  93         *      ndelay_off(fd);
  94         */
  95 term:
  96        free(buf);
  97        return 1; /* "terminate" */
  98}
  99
 100static int do_timeout(void **paramp UNUSED_PARAM)
 101{
 102        return 1; /* terminate session */
 103}
 104
 105static void inetd_mode(void)
 106{
 107        identd_buf_t *buf = xzalloc(sizeof(*buf));
 108        /* buf->pos = 0; - xzalloc did it */
 109        do
 110                alarm(TIMEOUT);
 111                /* Note: we do NOT want nonblocking I/O here! */
 112        while (do_rd(0, (void*)&buf) == 0);
 113}
 114
 115int fakeidentd_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
 116int fakeidentd_main(int argc UNUSED_PARAM, char **argv)
 117{
 118        enum {
 119                OPT_foreground = 0x1,
 120                OPT_inetd      = 0x2,
 121                OPT_inetdwait  = 0x4,
 122                OPT_fiw        = 0x7,
 123                OPT_bindaddr   = 0x8,
 124        };
 125
 126        const char *bind_address = NULL;
 127        unsigned opt;
 128        int fd;
 129
 130        setup_common_bufsiz();
 131
 132        opt = getopt32(argv, "fiwb:", &bind_address);
 133        strcpy(bogouser, "nobody");
 134        if (argv[optind])
 135                strncpy(bogouser, argv[optind], COMMON_BUFSIZE - 1);
 136
 137        /* Daemonize if no -f and no -i and no -w */
 138        if (!(opt & OPT_fiw))
 139                bb_daemonize_or_rexec(0, argv);
 140
 141        /* Where to log in inetd modes? "Classic" inetd
 142         * probably has its stderr /dev/null'ed (we need log to syslog?),
 143         * but daemontools-like utilities usually expect that children
 144         * log to stderr. I like daemontools more. Go their way.
 145         * (Or maybe we need yet another option "log to syslog") */
 146        if (!(opt & OPT_fiw) /* || (opt & OPT_syslog) */) {
 147                openlog(applet_name, LOG_PID, LOG_DAEMON);
 148                logmode = LOGMODE_SYSLOG;
 149        }
 150
 151        if (opt & OPT_inetd) {
 152                inetd_mode();
 153                return 0;
 154        }
 155
 156        /* Ignore closed connections when writing */
 157        signal(SIGPIPE, SIG_IGN);
 158
 159        fd = 0;
 160        if (!(opt & OPT_inetdwait)) {
 161                fd = create_and_bind_stream_or_die(bind_address,
 162                                bb_lookup_port("identd", "tcp", 113));
 163                xlisten(fd, 5);
 164        }
 165
 166        isrv_run(fd, new_peer, do_rd, /*do_wr:*/ NULL, do_timeout,
 167                        TIMEOUT, (opt & OPT_inetdwait) ? TIMEOUT : 0);
 168        return 0;
 169}
 170