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