blob: 3673db715e45b58a8f78f7f0192fa33fff61f2f7
1 | /* vi: set sw=4 ts=4: */ |
2 | /* |
3 | * Generic non-forking server infrastructure. |
4 | * Intended to make writing telnetd-type servers easier. |
5 | * |
6 | * Copyright (C) 2007 Denys Vlasenko |
7 | * |
8 | * Licensed under GPLv2, see file LICENSE in this source tree. |
9 | */ |
10 | |
11 | #include "libbb.h" |
12 | #include "isrv.h" |
13 | |
14 | #define DEBUG 0 |
15 | |
16 | #if DEBUG |
17 | #define DPRINTF(args...) bb_error_msg(args) |
18 | #else |
19 | #define DPRINTF(args...) ((void)0) |
20 | #endif |
21 | |
22 | /* Helpers */ |
23 | |
24 | /* Opaque structure */ |
25 | |
26 | struct isrv_state_t { |
27 | short *fd2peer; /* one per registered fd */ |
28 | void **param_tbl; /* one per registered peer */ |
29 | /* one per registered peer; doesn't exist if !timeout */ |
30 | time_t *timeo_tbl; |
31 | int (*new_peer)(isrv_state_t *state, int fd); |
32 | time_t curtime; |
33 | int timeout; |
34 | int fd_count; |
35 | int peer_count; |
36 | int wr_count; |
37 | fd_set rd; |
38 | fd_set wr; |
39 | }; |
40 | #define FD2PEER (state->fd2peer) |
41 | #define PARAM_TBL (state->param_tbl) |
42 | #define TIMEO_TBL (state->timeo_tbl) |
43 | #define CURTIME (state->curtime) |
44 | #define TIMEOUT (state->timeout) |
45 | #define FD_COUNT (state->fd_count) |
46 | #define PEER_COUNT (state->peer_count) |
47 | #define WR_COUNT (state->wr_count) |
48 | |
49 | /* callback */ |
50 | void isrv_want_rd(isrv_state_t *state, int fd) |
51 | { |
52 | FD_SET(fd, &state->rd); |
53 | } |
54 | |
55 | /* callback */ |
56 | void isrv_want_wr(isrv_state_t *state, int fd) |
57 | { |
58 | if (!FD_ISSET(fd, &state->wr)) { |
59 | WR_COUNT++; |
60 | FD_SET(fd, &state->wr); |
61 | } |
62 | } |
63 | |
64 | /* callback */ |
65 | void isrv_dont_want_rd(isrv_state_t *state, int fd) |
66 | { |
67 | FD_CLR(fd, &state->rd); |
68 | } |
69 | |
70 | /* callback */ |
71 | void isrv_dont_want_wr(isrv_state_t *state, int fd) |
72 | { |
73 | if (FD_ISSET(fd, &state->wr)) { |
74 | WR_COUNT--; |
75 | FD_CLR(fd, &state->wr); |
76 | } |
77 | } |
78 | |
79 | /* callback */ |
80 | int isrv_register_fd(isrv_state_t *state, int peer, int fd) |
81 | { |
82 | int n; |
83 | |
84 | DPRINTF("register_fd(peer:%d,fd:%d)", peer, fd); |
85 | |
86 | if (FD_COUNT >= FD_SETSIZE) return -1; |
87 | if (FD_COUNT <= fd) { |
88 | n = FD_COUNT; |
89 | FD_COUNT = fd + 1; |
90 | |
91 | DPRINTF("register_fd: FD_COUNT %d", FD_COUNT); |
92 | |
93 | FD2PEER = xrealloc(FD2PEER, FD_COUNT * sizeof(FD2PEER[0])); |
94 | while (n < fd) FD2PEER[n++] = -1; |
95 | } |
96 | |
97 | DPRINTF("register_fd: FD2PEER[%d] = %d", fd, peer); |
98 | |
99 | FD2PEER[fd] = peer; |
100 | return 0; |
101 | } |
102 | |
103 | /* callback */ |
104 | void isrv_close_fd(isrv_state_t *state, int fd) |
105 | { |
106 | DPRINTF("close_fd(%d)", fd); |
107 | |
108 | close(fd); |
109 | isrv_dont_want_rd(state, fd); |
110 | if (WR_COUNT) isrv_dont_want_wr(state, fd); |
111 | |
112 | FD2PEER[fd] = -1; |
113 | if (fd == FD_COUNT-1) { |
114 | do fd--; while (fd >= 0 && FD2PEER[fd] == -1); |
115 | FD_COUNT = fd + 1; |
116 | |
117 | DPRINTF("close_fd: FD_COUNT %d", FD_COUNT); |
118 | |
119 | FD2PEER = xrealloc(FD2PEER, FD_COUNT * sizeof(FD2PEER[0])); |
120 | } |
121 | } |
122 | |
123 | /* callback */ |
124 | int isrv_register_peer(isrv_state_t *state, void *param) |
125 | { |
126 | int n; |
127 | |
128 | if (PEER_COUNT >= FD_SETSIZE) return -1; |
129 | n = PEER_COUNT++; |
130 | |
131 | DPRINTF("register_peer: PEER_COUNT %d", PEER_COUNT); |
132 | |
133 | PARAM_TBL = xrealloc(PARAM_TBL, PEER_COUNT * sizeof(PARAM_TBL[0])); |
134 | PARAM_TBL[n] = param; |
135 | if (TIMEOUT) { |
136 | TIMEO_TBL = xrealloc(TIMEO_TBL, PEER_COUNT * sizeof(TIMEO_TBL[0])); |
137 | TIMEO_TBL[n] = CURTIME; |
138 | } |
139 | return n; |
140 | } |
141 | |
142 | static void remove_peer(isrv_state_t *state, int peer) |
143 | { |
144 | int movesize; |
145 | int fd; |
146 | |
147 | DPRINTF("remove_peer(%d)", peer); |
148 | |
149 | fd = FD_COUNT - 1; |
150 | while (fd >= 0) { |
151 | if (FD2PEER[fd] == peer) { |
152 | isrv_close_fd(state, fd); |
153 | fd--; |
154 | continue; |
155 | } |
156 | if (FD2PEER[fd] > peer) |
157 | FD2PEER[fd]--; |
158 | fd--; |
159 | } |
160 | |
161 | PEER_COUNT--; |
162 | DPRINTF("remove_peer: PEER_COUNT %d", PEER_COUNT); |
163 | |
164 | movesize = (PEER_COUNT - peer) * sizeof(void*); |
165 | if (movesize > 0) { |
166 | memcpy(&PARAM_TBL[peer], &PARAM_TBL[peer+1], movesize); |
167 | if (TIMEOUT) |
168 | memcpy(&TIMEO_TBL[peer], &TIMEO_TBL[peer+1], movesize); |
169 | } |
170 | PARAM_TBL = xrealloc(PARAM_TBL, PEER_COUNT * sizeof(PARAM_TBL[0])); |
171 | if (TIMEOUT) |
172 | TIMEO_TBL = xrealloc(TIMEO_TBL, PEER_COUNT * sizeof(TIMEO_TBL[0])); |
173 | } |
174 | |
175 | static void handle_accept(isrv_state_t *state, int fd) |
176 | { |
177 | int n, newfd; |
178 | |
179 | /* suppress gcc warning "cast from ptr to int of different size" */ |
180 | fcntl(fd, F_SETFL, (int)(ptrdiff_t)(PARAM_TBL[0]) | O_NONBLOCK); |
181 | newfd = accept(fd, NULL, 0); |
182 | fcntl(fd, F_SETFL, (int)(ptrdiff_t)(PARAM_TBL[0])); |
183 | if (newfd < 0) { |
184 | if (errno == EAGAIN) return; |
185 | /* Most probably someone gave us wrong fd type |
186 | * (for example, non-socket). Don't want |
187 | * to loop forever. */ |
188 | bb_perror_msg_and_die("accept"); |
189 | } |
190 | |
191 | DPRINTF("new_peer(%d)", newfd); |
192 | n = state->new_peer(state, newfd); |
193 | if (n) |
194 | remove_peer(state, n); /* unsuccesful peer start */ |
195 | } |
196 | |
197 | static void handle_fd_set(isrv_state_t *state, fd_set *fds, int (*h)(int, void **)) |
198 | { |
199 | enum { LONG_CNT = sizeof(fd_set) / sizeof(long) }; |
200 | int fds_pos; |
201 | int fd, peer; |
202 | /* need to know value at _the beginning_ of this routine */ |
203 | int fd_cnt = FD_COUNT; |
204 | |
205 | BUILD_BUG_ON(LONG_CNT * sizeof(long) != sizeof(fd_set)); |
206 | |
207 | fds_pos = 0; |
208 | while (1) { |
209 | /* Find next nonzero bit */ |
210 | while (fds_pos < LONG_CNT) { |
211 | if (((long*)fds)[fds_pos] == 0) { |
212 | fds_pos++; |
213 | continue; |
214 | } |
215 | /* Found non-zero word */ |
216 | fd = fds_pos * sizeof(long)*8; /* word# -> bit# */ |
217 | while (1) { |
218 | if (FD_ISSET(fd, fds)) { |
219 | FD_CLR(fd, fds); |
220 | goto found_fd; |
221 | } |
222 | fd++; |
223 | } |
224 | } |
225 | break; /* all words are zero */ |
226 | found_fd: |
227 | if (fd >= fd_cnt) { /* paranoia */ |
228 | DPRINTF("handle_fd_set: fd > fd_cnt?? (%d > %d)", |
229 | fd, fd_cnt); |
230 | break; |
231 | } |
232 | DPRINTF("handle_fd_set: fd %d is active", fd); |
233 | peer = FD2PEER[fd]; |
234 | if (peer < 0) |
235 | continue; /* peer is already gone */ |
236 | if (peer == 0) { |
237 | handle_accept(state, fd); |
238 | continue; |
239 | } |
240 | DPRINTF("h(fd:%d)", fd); |
241 | if (h(fd, &PARAM_TBL[peer])) { |
242 | /* this peer is gone */ |
243 | remove_peer(state, peer); |
244 | } else if (TIMEOUT) { |
245 | TIMEO_TBL[peer] = monotonic_sec(); |
246 | } |
247 | } |
248 | } |
249 | |
250 | static void handle_timeout(isrv_state_t *state, int (*do_timeout)(void **)) |
251 | { |
252 | int n, peer; |
253 | peer = PEER_COUNT-1; |
254 | /* peer 0 is not checked */ |
255 | while (peer > 0) { |
256 | DPRINTF("peer %d: time diff %d", peer, |
257 | (int)(CURTIME - TIMEO_TBL[peer])); |
258 | if ((CURTIME - TIMEO_TBL[peer]) >= TIMEOUT) { |
259 | DPRINTF("peer %d: do_timeout()", peer); |
260 | n = do_timeout(&PARAM_TBL[peer]); |
261 | if (n) |
262 | remove_peer(state, peer); |
263 | } |
264 | peer--; |
265 | } |
266 | } |
267 | |
268 | /* Driver */ |
269 | void isrv_run( |
270 | int listen_fd, |
271 | int (*new_peer)(isrv_state_t *state, int fd), |
272 | int (*do_rd)(int fd, void **), |
273 | int (*do_wr)(int fd, void **), |
274 | int (*do_timeout)(void **), |
275 | int timeout, |
276 | int linger_timeout) |
277 | { |
278 | isrv_state_t *state = xzalloc(sizeof(*state)); |
279 | state->new_peer = new_peer; |
280 | state->timeout = timeout; |
281 | |
282 | /* register "peer" #0 - it will accept new connections */ |
283 | isrv_register_peer(state, NULL); |
284 | isrv_register_fd(state, /*peer:*/ 0, listen_fd); |
285 | isrv_want_rd(state, listen_fd); |
286 | /* remember flags to make blocking<->nonblocking switch faster */ |
287 | /* (suppress gcc warning "cast from ptr to int of different size") */ |
288 | PARAM_TBL[0] = (void*)(ptrdiff_t)(fcntl(listen_fd, F_GETFL)); |
289 | |
290 | while (1) { |
291 | struct timeval tv; |
292 | fd_set rd; |
293 | fd_set wr; |
294 | fd_set *wrp = NULL; |
295 | int n; |
296 | |
297 | tv.tv_sec = timeout; |
298 | if (PEER_COUNT <= 1) |
299 | tv.tv_sec = linger_timeout; |
300 | tv.tv_usec = 0; |
301 | rd = state->rd; |
302 | if (WR_COUNT) { |
303 | wr = state->wr; |
304 | wrp = ≀ |
305 | } |
306 | |
307 | DPRINTF("run: select(FD_COUNT:%d,timeout:%d)...", |
308 | FD_COUNT, (int)tv.tv_sec); |
309 | n = select(FD_COUNT, &rd, wrp, NULL, tv.tv_sec ? &tv : NULL); |
310 | DPRINTF("run: ...select:%d", n); |
311 | |
312 | if (n < 0) { |
313 | if (errno != EINTR) |
314 | bb_perror_msg("select"); |
315 | continue; |
316 | } |
317 | |
318 | if (n == 0 && linger_timeout && PEER_COUNT <= 1) |
319 | break; |
320 | |
321 | if (timeout) { |
322 | time_t t = monotonic_sec(); |
323 | if (t != CURTIME) { |
324 | CURTIME = t; |
325 | handle_timeout(state, do_timeout); |
326 | } |
327 | } |
328 | if (n > 0) { |
329 | handle_fd_set(state, &rd, do_rd); |
330 | if (wrp) |
331 | handle_fd_set(state, wrp, do_wr); |
332 | } |
333 | } |
334 | DPRINTF("run: bailout"); |
335 | /* NB: accept socket is not closed. Caller is to decide what to do */ |
336 | } |
337 |