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Commit | Line | Data |
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a87e8be2 LT |
1 | #include "cache.h" |
2 | #include "pkt-line.h" | |
eaa94919 LT |
3 | #include <signal.h> |
4 | #include <sys/wait.h> | |
a87e8be2 | 5 | #include <sys/socket.h> |
df076bdb | 6 | #include <netdb.h> |
a87e8be2 LT |
7 | #include <netinet/in.h> |
8 | ||
e64e1b79 | 9 | static const char daemon_usage[] = "git-daemon [--inetd | --port=n]"; |
a87e8be2 LT |
10 | |
11 | static int upload(char *dir, int dirlen) | |
12 | { | |
13 | if (chdir(dir) < 0) | |
14 | return -1; | |
15 | chdir(".git"); | |
16 | ||
17 | /* | |
18 | * Security on the cheap. | |
19 | * | |
20 | * We want a readable HEAD, usable "objects" directory, and | |
21 | * a "git-daemon-export-ok" flag that says that the other side | |
22 | * is ok with us doing this. | |
23 | */ | |
24 | if (access("git-daemon-export-ok", F_OK) || | |
25 | access("objects/00", X_OK) || | |
26 | access("HEAD", R_OK)) | |
27 | return -1; | |
28 | ||
02d57da4 LT |
29 | /* |
30 | * We'll ignore SIGTERM from now on, we have a | |
31 | * good client. | |
32 | */ | |
33 | signal(SIGTERM, SIG_IGN); | |
34 | ||
a87e8be2 LT |
35 | /* git-upload-pack only ever reads stuff, so this is safe */ |
36 | execlp("git-upload-pack", "git-upload-pack", ".", NULL); | |
37 | return -1; | |
38 | } | |
39 | ||
7d80694a | 40 | static int execute(void) |
a87e8be2 | 41 | { |
7d80694a LT |
42 | static char line[1000]; |
43 | int len; | |
44 | ||
45 | len = packet_read_line(0, line, sizeof(line)); | |
46 | ||
47 | if (len && line[len-1] == '\n') | |
48 | line[--len] = 0; | |
49 | ||
a87e8be2 LT |
50 | if (!strncmp("git-upload-pack /", line, 17)) |
51 | return upload(line + 16, len - 16); | |
52 | ||
53 | fprintf(stderr, "got bad connection '%s'\n", line); | |
54 | return -1; | |
55 | } | |
56 | ||
66e631de LT |
57 | |
58 | /* | |
59 | * We count spawned/reaped separately, just to avoid any | |
60 | * races when updating them from signals. The SIGCHLD handler | |
61 | * will only update children_reaped, and the fork logic will | |
62 | * only update children_spawned. | |
63 | * | |
64 | * MAX_CHILDREN should be a power-of-two to make the modulus | |
65 | * operation cheap. It should also be at least twice | |
66 | * the maximum number of connections we will ever allow. | |
67 | */ | |
68 | #define MAX_CHILDREN 128 | |
69 | ||
70 | static int max_connections = 25; | |
71 | ||
72 | /* These are updated by the signal handler */ | |
73 | static volatile unsigned int children_reaped = 0; | |
4d8fa916 | 74 | static pid_t dead_child[MAX_CHILDREN]; |
66e631de LT |
75 | |
76 | /* These are updated by the main loop */ | |
77 | static unsigned int children_spawned = 0; | |
78 | static unsigned int children_deleted = 0; | |
79 | ||
4d8fa916 | 80 | static struct child { |
66e631de | 81 | pid_t pid; |
df076bdb YH |
82 | socklen_t addrlen; |
83 | struct sockaddr_storage address; | |
66e631de LT |
84 | } live_child[MAX_CHILDREN]; |
85 | ||
df076bdb | 86 | static void add_child(int idx, pid_t pid, struct sockaddr *addr, socklen_t addrlen) |
66e631de LT |
87 | { |
88 | live_child[idx].pid = pid; | |
89 | live_child[idx].addrlen = addrlen; | |
df076bdb | 90 | memcpy(&live_child[idx].address, addr, addrlen); |
66e631de LT |
91 | } |
92 | ||
93 | /* | |
94 | * Walk from "deleted" to "spawned", and remove child "pid". | |
95 | * | |
96 | * We move everything up by one, since the new "deleted" will | |
97 | * be one higher. | |
98 | */ | |
99 | static void remove_child(pid_t pid, unsigned deleted, unsigned spawned) | |
100 | { | |
101 | struct child n; | |
102 | ||
103 | deleted %= MAX_CHILDREN; | |
104 | spawned %= MAX_CHILDREN; | |
105 | if (live_child[deleted].pid == pid) { | |
106 | live_child[deleted].pid = -1; | |
107 | return; | |
108 | } | |
109 | n = live_child[deleted]; | |
110 | for (;;) { | |
111 | struct child m; | |
112 | deleted = (deleted + 1) % MAX_CHILDREN; | |
113 | if (deleted == spawned) | |
114 | die("could not find dead child %d\n", pid); | |
115 | m = live_child[deleted]; | |
116 | live_child[deleted] = n; | |
117 | if (m.pid == pid) | |
118 | return; | |
119 | n = m; | |
120 | } | |
121 | } | |
122 | ||
123 | /* | |
124 | * This gets called if the number of connections grows | |
125 | * past "max_connections". | |
126 | * | |
127 | * We _should_ start off by searching for connections | |
128 | * from the same IP, and if there is some address wth | |
129 | * multiple connections, we should kill that first. | |
130 | * | |
131 | * As it is, we just "randomly" kill 25% of the connections, | |
132 | * and our pseudo-random generator sucks too. I have no | |
133 | * shame. | |
134 | * | |
135 | * Really, this is just a place-holder for a _real_ algorithm. | |
136 | */ | |
02d57da4 | 137 | static void kill_some_children(int signo, unsigned start, unsigned stop) |
66e631de LT |
138 | { |
139 | start %= MAX_CHILDREN; | |
140 | stop %= MAX_CHILDREN; | |
141 | while (start != stop) { | |
142 | if (!(start & 3)) | |
02d57da4 | 143 | kill(live_child[start].pid, signo); |
66e631de LT |
144 | start = (start + 1) % MAX_CHILDREN; |
145 | } | |
146 | } | |
147 | ||
02d57da4 | 148 | static void check_max_connections(void) |
a87e8be2 | 149 | { |
02d57da4 | 150 | for (;;) { |
eaa94919 | 151 | int active; |
66e631de | 152 | unsigned spawned, reaped, deleted; |
eaa94919 | 153 | |
66e631de | 154 | spawned = children_spawned; |
66e631de LT |
155 | reaped = children_reaped; |
156 | deleted = children_deleted; | |
157 | ||
158 | while (deleted < reaped) { | |
159 | pid_t pid = dead_child[deleted % MAX_CHILDREN]; | |
160 | remove_child(pid, deleted, spawned); | |
161 | deleted++; | |
162 | } | |
163 | children_deleted = deleted; | |
164 | ||
165 | active = spawned - deleted; | |
02d57da4 LT |
166 | if (active <= max_connections) |
167 | break; | |
66e631de | 168 | |
02d57da4 LT |
169 | /* Kill some unstarted connections with SIGTERM */ |
170 | kill_some_children(SIGTERM, deleted, spawned); | |
171 | if (active <= max_connections << 1) | |
172 | break; | |
173 | ||
174 | /* If the SIGTERM thing isn't helping use SIGKILL */ | |
175 | kill_some_children(SIGKILL, deleted, spawned); | |
176 | sleep(1); | |
177 | } | |
178 | } | |
179 | ||
df076bdb | 180 | static void handle(int incoming, struct sockaddr *addr, socklen_t addrlen) |
02d57da4 LT |
181 | { |
182 | pid_t pid = fork(); | |
183 | ||
184 | if (pid) { | |
185 | unsigned idx; | |
186 | ||
187 | close(incoming); | |
188 | if (pid < 0) | |
189 | return; | |
190 | ||
191 | idx = children_spawned % MAX_CHILDREN; | |
192 | children_spawned++; | |
193 | add_child(idx, pid, addr, addrlen); | |
66e631de | 194 | |
02d57da4 | 195 | check_max_connections(); |
a87e8be2 LT |
196 | return; |
197 | } | |
198 | ||
199 | dup2(incoming, 0); | |
200 | dup2(incoming, 1); | |
201 | close(incoming); | |
7d80694a | 202 | exit(execute()); |
a87e8be2 LT |
203 | } |
204 | ||
eaa94919 LT |
205 | static void child_handler(int signo) |
206 | { | |
207 | for (;;) { | |
66e631de LT |
208 | pid_t pid = waitpid(-1, NULL, WNOHANG); |
209 | ||
210 | if (pid > 0) { | |
211 | unsigned reaped = children_reaped; | |
212 | dead_child[reaped % MAX_CHILDREN] = pid; | |
213 | children_reaped = reaped + 1; | |
eaa94919 LT |
214 | continue; |
215 | } | |
216 | break; | |
217 | } | |
218 | } | |
219 | ||
a87e8be2 LT |
220 | static int serve(int port) |
221 | { | |
df076bdb YH |
222 | struct addrinfo hints, *ai0, *ai; |
223 | int gai; | |
224 | int socknum = 0, *socklist = NULL; | |
225 | int maxfd = -1; | |
226 | fd_set fds_init, fds; | |
227 | char pbuf[NI_MAXSERV]; | |
a87e8be2 | 228 | |
eaa94919 | 229 | signal(SIGCHLD, child_handler); |
df076bdb YH |
230 | |
231 | sprintf(pbuf, "%d", port); | |
232 | memset(&hints, 0, sizeof(hints)); | |
233 | hints.ai_family = AF_UNSPEC; | |
234 | hints.ai_socktype = SOCK_STREAM; | |
235 | hints.ai_protocol = IPPROTO_TCP; | |
236 | hints.ai_flags = AI_PASSIVE; | |
237 | ||
238 | gai = getaddrinfo(NULL, pbuf, &hints, &ai0); | |
239 | if (gai) | |
240 | die("getaddrinfo() failed: %s\n", gai_strerror(gai)); | |
241 | ||
242 | FD_ZERO(&fds_init); | |
243 | ||
244 | for (ai = ai0; ai; ai = ai->ai_next) { | |
245 | int sockfd; | |
246 | int *newlist; | |
247 | ||
248 | sockfd = socket(ai->ai_family, ai->ai_socktype, ai->ai_protocol); | |
249 | if (sockfd < 0) | |
250 | continue; | |
251 | if (sockfd >= FD_SETSIZE) { | |
252 | error("too large socket descriptor."); | |
253 | close(sockfd); | |
254 | continue; | |
255 | } | |
256 | ||
257 | #ifdef IPV6_V6ONLY | |
258 | if (ai->ai_family == AF_INET6) { | |
259 | int on = 1; | |
260 | setsockopt(sockfd, IPPROTO_IPV6, IPV6_V6ONLY, | |
261 | &on, sizeof(on)); | |
262 | /* Note: error is not fatal */ | |
263 | } | |
264 | #endif | |
265 | ||
266 | if (bind(sockfd, ai->ai_addr, ai->ai_addrlen) < 0) { | |
267 | close(sockfd); | |
268 | continue; /* not fatal */ | |
269 | } | |
270 | if (listen(sockfd, 5) < 0) { | |
271 | close(sockfd); | |
272 | continue; /* not fatal */ | |
273 | } | |
274 | ||
275 | newlist = realloc(socklist, sizeof(int) * (socknum + 1)); | |
276 | if (!newlist) | |
277 | die("memory allocation failed: %s", strerror(errno)); | |
278 | ||
279 | socklist = newlist; | |
280 | socklist[socknum++] = sockfd; | |
281 | ||
282 | FD_SET(sockfd, &fds_init); | |
283 | if (maxfd < sockfd) | |
284 | maxfd = sockfd; | |
285 | } | |
286 | ||
287 | freeaddrinfo(ai0); | |
288 | ||
289 | if (socknum == 0) | |
290 | die("unable to allocate any listen sockets on port %u", port); | |
a87e8be2 LT |
291 | |
292 | for (;;) { | |
df076bdb YH |
293 | int i; |
294 | fds = fds_init; | |
295 | ||
296 | if (select(maxfd + 1, &fds, NULL, NULL, NULL) < 0) { | |
297 | error("select failed, resuming: %s", strerror(errno)); | |
298 | sleep(1); | |
299 | continue; | |
300 | } | |
301 | ||
302 | for (i = 0; i < socknum; i++) { | |
303 | int sockfd = socklist[i]; | |
304 | ||
305 | if (FD_ISSET(sockfd, &fds)) { | |
306 | struct sockaddr_storage ss; | |
307 | socklen_t sslen = sizeof(ss); | |
308 | int incoming = accept(sockfd, (struct sockaddr *)&ss, &sslen); | |
309 | if (incoming < 0) { | |
310 | switch (errno) { | |
311 | case EAGAIN: | |
312 | case EINTR: | |
313 | case ECONNABORTED: | |
314 | continue; | |
315 | default: | |
316 | die("accept returned %s", strerror(errno)); | |
317 | } | |
318 | } | |
319 | handle(incoming, (struct sockaddr *)&ss, sslen); | |
a87e8be2 LT |
320 | } |
321 | } | |
a87e8be2 LT |
322 | } |
323 | } | |
324 | ||
325 | int main(int argc, char **argv) | |
326 | { | |
327 | int port = DEFAULT_GIT_PORT; | |
e64e1b79 | 328 | int inetd_mode = 0; |
a87e8be2 LT |
329 | int i; |
330 | ||
331 | for (i = 1; i < argc; i++) { | |
332 | char *arg = argv[i]; | |
333 | ||
334 | if (!strncmp(arg, "--port=", 7)) { | |
335 | char *end; | |
336 | unsigned long n; | |
337 | n = strtoul(arg+7, &end, 0); | |
338 | if (arg[7] && !*end) { | |
339 | port = n; | |
340 | continue; | |
341 | } | |
342 | } | |
e64e1b79 LT |
343 | |
344 | if (!strcmp(arg, "--inetd")) { | |
345 | inetd_mode = 1; | |
346 | continue; | |
347 | } | |
348 | ||
a87e8be2 LT |
349 | usage(daemon_usage); |
350 | } | |
351 | ||
e64e1b79 LT |
352 | if (inetd_mode) |
353 | return execute(); | |
354 | ||
a87e8be2 LT |
355 | return serve(port); |
356 | } |