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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 LT |
5 | #include <sys/socket.h> |
6 | #include <netinet/in.h> | |
66e631de | 7 | #include <arpa/inet.h> |
a87e8be2 | 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; | |
74 | pid_t dead_child[MAX_CHILDREN]; | |
75 | ||
76 | /* These are updated by the main loop */ | |
77 | static unsigned int children_spawned = 0; | |
78 | static unsigned int children_deleted = 0; | |
79 | ||
80 | struct child { | |
81 | pid_t pid; | |
82 | int addrlen; | |
83 | struct sockaddr_in address; | |
84 | } live_child[MAX_CHILDREN]; | |
85 | ||
86 | static void add_child(int idx, pid_t pid, struct sockaddr_in *addr, int addrlen) | |
87 | { | |
88 | live_child[idx].pid = pid; | |
89 | live_child[idx].addrlen = addrlen; | |
90 | live_child[idx].address = *addr; | |
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 | ||
180 | static void handle(int incoming, struct sockaddr_in *addr, int addrlen) | |
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 | { | |
222 | int sockfd; | |
223 | struct sockaddr_in addr; | |
224 | ||
eaa94919 | 225 | signal(SIGCHLD, child_handler); |
a87e8be2 LT |
226 | sockfd = socket(PF_INET, SOCK_STREAM, IPPROTO_IP); |
227 | if (sockfd < 0) | |
228 | die("unable to open socket (%s)", strerror(errno)); | |
229 | memset(&addr, 0, sizeof(addr)); | |
230 | addr.sin_port = htons(port); | |
231 | addr.sin_family = AF_INET; | |
232 | if (bind(sockfd, (void *)&addr, sizeof(addr)) < 0) | |
233 | die("unable to bind to port %d (%s)", port, strerror(errno)); | |
234 | if (listen(sockfd, 5) < 0) | |
235 | die("unable to listen to port %d (%s)", port, strerror(errno)); | |
236 | ||
237 | for (;;) { | |
238 | struct sockaddr_in in; | |
239 | socklen_t addrlen = sizeof(in); | |
240 | int incoming = accept(sockfd, (void *)&in, &addrlen); | |
241 | ||
242 | if (incoming < 0) { | |
243 | switch (errno) { | |
244 | case EAGAIN: | |
245 | case EINTR: | |
246 | case ECONNABORTED: | |
247 | continue; | |
248 | default: | |
249 | die("accept returned %s", strerror(errno)); | |
250 | } | |
251 | } | |
252 | handle(incoming, &in, addrlen); | |
253 | } | |
254 | } | |
255 | ||
256 | int main(int argc, char **argv) | |
257 | { | |
258 | int port = DEFAULT_GIT_PORT; | |
e64e1b79 | 259 | int inetd_mode = 0; |
a87e8be2 LT |
260 | int i; |
261 | ||
262 | for (i = 1; i < argc; i++) { | |
263 | char *arg = argv[i]; | |
264 | ||
265 | if (!strncmp(arg, "--port=", 7)) { | |
266 | char *end; | |
267 | unsigned long n; | |
268 | n = strtoul(arg+7, &end, 0); | |
269 | if (arg[7] && !*end) { | |
270 | port = n; | |
271 | continue; | |
272 | } | |
273 | } | |
e64e1b79 LT |
274 | |
275 | if (!strcmp(arg, "--inetd")) { | |
276 | inetd_mode = 1; | |
277 | continue; | |
278 | } | |
279 | ||
a87e8be2 LT |
280 | usage(daemon_usage); |
281 | } | |
282 | ||
e64e1b79 LT |
283 | if (inetd_mode) |
284 | return execute(); | |
285 | ||
a87e8be2 LT |
286 | return serve(port); |
287 | } |