add macro REALLOC_ARRAY
[git] / credential-cache--daemon.c
1 #include "cache.h"
2 #include "credential.h"
3 #include "unix-socket.h"
4 #include "sigchain.h"
5
6 static const char *socket_path;
7
8 static void cleanup_socket(void)
9 {
10         if (socket_path)
11                 unlink(socket_path);
12 }
13
14 static void cleanup_socket_on_signal(int sig)
15 {
16         cleanup_socket();
17         sigchain_pop(sig);
18         raise(sig);
19 }
20
21 struct credential_cache_entry {
22         struct credential item;
23         unsigned long expiration;
24 };
25 static struct credential_cache_entry *entries;
26 static int entries_nr;
27 static int entries_alloc;
28
29 static void cache_credential(struct credential *c, int timeout)
30 {
31         struct credential_cache_entry *e;
32
33         ALLOC_GROW(entries, entries_nr + 1, entries_alloc);
34         e = &entries[entries_nr++];
35
36         /* take ownership of pointers */
37         memcpy(&e->item, c, sizeof(*c));
38         memset(c, 0, sizeof(*c));
39         e->expiration = time(NULL) + timeout;
40 }
41
42 static struct credential_cache_entry *lookup_credential(const struct credential *c)
43 {
44         int i;
45         for (i = 0; i < entries_nr; i++) {
46                 struct credential *e = &entries[i].item;
47                 if (credential_match(c, e))
48                         return &entries[i];
49         }
50         return NULL;
51 }
52
53 static void remove_credential(const struct credential *c)
54 {
55         struct credential_cache_entry *e;
56
57         e = lookup_credential(c);
58         if (e)
59                 e->expiration = 0;
60 }
61
62 static int check_expirations(void)
63 {
64         static unsigned long wait_for_entry_until;
65         int i = 0;
66         unsigned long now = time(NULL);
67         unsigned long next = (unsigned long)-1;
68
69         /*
70          * Initially give the client 30 seconds to actually contact us
71          * and store a credential before we decide there's no point in
72          * keeping the daemon around.
73          */
74         if (!wait_for_entry_until)
75                 wait_for_entry_until = now + 30;
76
77         while (i < entries_nr) {
78                 if (entries[i].expiration <= now) {
79                         entries_nr--;
80                         credential_clear(&entries[i].item);
81                         if (i != entries_nr)
82                                 memcpy(&entries[i], &entries[entries_nr], sizeof(*entries));
83                         /*
84                          * Stick around 30 seconds in case a new credential
85                          * shows up (e.g., because we just removed a failed
86                          * one, and we will soon get the correct one).
87                          */
88                         wait_for_entry_until = now + 30;
89                 }
90                 else {
91                         if (entries[i].expiration < next)
92                                 next = entries[i].expiration;
93                         i++;
94                 }
95         }
96
97         if (!entries_nr) {
98                 if (wait_for_entry_until <= now)
99                         return 0;
100                 next = wait_for_entry_until;
101         }
102
103         return next - now;
104 }
105
106 static int read_request(FILE *fh, struct credential *c,
107                         struct strbuf *action, int *timeout) {
108         static struct strbuf item = STRBUF_INIT;
109         const char *p;
110
111         strbuf_getline(&item, fh, '\n');
112         if (!skip_prefix(item.buf, "action=", &p))
113                 return error("client sent bogus action line: %s", item.buf);
114         strbuf_addstr(action, p);
115
116         strbuf_getline(&item, fh, '\n');
117         if (!skip_prefix(item.buf, "timeout=", &p))
118                 return error("client sent bogus timeout line: %s", item.buf);
119         *timeout = atoi(p);
120
121         if (credential_read(c, fh) < 0)
122                 return -1;
123         return 0;
124 }
125
126 static void serve_one_client(FILE *in, FILE *out)
127 {
128         struct credential c = CREDENTIAL_INIT;
129         struct strbuf action = STRBUF_INIT;
130         int timeout = -1;
131
132         if (read_request(in, &c, &action, &timeout) < 0)
133                 /* ignore error */ ;
134         else if (!strcmp(action.buf, "get")) {
135                 struct credential_cache_entry *e = lookup_credential(&c);
136                 if (e) {
137                         fprintf(out, "username=%s\n", e->item.username);
138                         fprintf(out, "password=%s\n", e->item.password);
139                 }
140         }
141         else if (!strcmp(action.buf, "exit"))
142                 exit(0);
143         else if (!strcmp(action.buf, "erase"))
144                 remove_credential(&c);
145         else if (!strcmp(action.buf, "store")) {
146                 if (timeout < 0)
147                         warning("cache client didn't specify a timeout");
148                 else if (!c.username || !c.password)
149                         warning("cache client gave us a partial credential");
150                 else {
151                         remove_credential(&c);
152                         cache_credential(&c, timeout);
153                 }
154         }
155         else
156                 warning("cache client sent unknown action: %s", action.buf);
157
158         credential_clear(&c);
159         strbuf_release(&action);
160 }
161
162 static int serve_cache_loop(int fd)
163 {
164         struct pollfd pfd;
165         unsigned long wakeup;
166
167         wakeup = check_expirations();
168         if (!wakeup)
169                 return 0;
170
171         pfd.fd = fd;
172         pfd.events = POLLIN;
173         if (poll(&pfd, 1, 1000 * wakeup) < 0) {
174                 if (errno != EINTR)
175                         die_errno("poll failed");
176                 return 1;
177         }
178
179         if (pfd.revents & POLLIN) {
180                 int client, client2;
181                 FILE *in, *out;
182
183                 client = accept(fd, NULL, NULL);
184                 if (client < 0) {
185                         warning("accept failed: %s", strerror(errno));
186                         return 1;
187                 }
188                 client2 = dup(client);
189                 if (client2 < 0) {
190                         warning("dup failed: %s", strerror(errno));
191                         close(client);
192                         return 1;
193                 }
194
195                 in = xfdopen(client, "r");
196                 out = xfdopen(client2, "w");
197                 serve_one_client(in, out);
198                 fclose(in);
199                 fclose(out);
200         }
201         return 1;
202 }
203
204 static void serve_cache(const char *socket_path)
205 {
206         int fd;
207
208         fd = unix_stream_listen(socket_path);
209         if (fd < 0)
210                 die_errno("unable to bind to '%s'", socket_path);
211
212         printf("ok\n");
213         fclose(stdout);
214
215         while (serve_cache_loop(fd))
216                 ; /* nothing */
217
218         close(fd);
219         unlink(socket_path);
220 }
221
222 static const char permissions_advice[] =
223 "The permissions on your socket directory are too loose; other\n"
224 "users may be able to read your cached credentials. Consider running:\n"
225 "\n"
226 "       chmod 0700 %s";
227 static void check_socket_directory(const char *path)
228 {
229         struct stat st;
230         char *path_copy = xstrdup(path);
231         char *dir = dirname(path_copy);
232
233         if (!stat(dir, &st)) {
234                 if (st.st_mode & 077)
235                         die(permissions_advice, dir);
236                 free(path_copy);
237                 return;
238         }
239
240         /*
241          * We must be sure to create the directory with the correct mode,
242          * not just chmod it after the fact; otherwise, there is a race
243          * condition in which somebody can chdir to it, sleep, then try to open
244          * our protected socket.
245          */
246         if (safe_create_leading_directories_const(dir) < 0)
247                 die_errno("unable to create directories for '%s'", dir);
248         if (mkdir(dir, 0700) < 0)
249                 die_errno("unable to mkdir '%s'", dir);
250         free(path_copy);
251 }
252
253 int main(int argc, const char **argv)
254 {
255         socket_path = argv[1];
256
257         if (!socket_path)
258                 die("usage: git-credential-cache--daemon <socket_path>");
259         check_socket_directory(socket_path);
260
261         atexit(cleanup_socket);
262         sigchain_push_common(cleanup_socket_on_signal);
263
264         serve_cache(socket_path);
265
266         return 0;
267 }