blob: a41405c333ad1dec6972eb63db2d853f2b535b72
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 | } |
158 |