git.oblomov.eu Git - git/blob - daemon.c

   1 #include "cache.h"
   2 #include "pkt-line.h"
   3 #include "exec_cmd.h"
   4 #include "run-command.h"
   5 #include "strbuf.h"
   6 #include "string-list.h"
   7
   8 #ifndef HOST_NAME_MAX
   9 #define HOST_NAME_MAX 256
  10 #endif
  11
  12 #ifdef NO_INITGROUPS
  13 #define initgroups(x, y) (0) /* nothing */
  14 #endif
  15
  16 static int log_syslog;
  17 static int verbose;
  18 static int reuseaddr;
  19 static int informative_errors;
  20
  21 static const char daemon_usage[] =
  22 "git daemon [--verbose] [--syslog] [--export-all]\n"
  23 "           [--timeout=<n>] [--init-timeout=<n>] [--max-connections=<n>]\n"
  24 "           [--strict-paths] [--base-path=<path>] [--base-path-relaxed]\n"
  25 "           [--user-path | --user-path=<path>]\n"
  26 "           [--interpolated-path=<path>]\n"
  27 "           [--reuseaddr] [--pid-file=<file>]\n"
  28 "           [--(enable|disable|allow-override|forbid-override)=<service>]\n"
  29 "           [--access-hook=<path>]\n"
  30 "           [--inetd | [--listen=<host_or_ipaddr>] [--port=<n>]\n"
  31 "                      [--detach] [--user=<user> [--group=<group>]]\n"
  32 "           [<directory>...]";
  33
  34 /* List of acceptable pathname prefixes */
  35 static char **ok_paths;
  36 static int strict_paths;
  37
  38 /* If this is set, git-daemon-export-ok is not required */
  39 static int export_all_trees;
  40
  41 /* Take all paths relative to this one if non-NULL */
  42 static const char *base_path;
  43 static const char *interpolated_path;
  44 static int base_path_relaxed;
  45
  46 /* If defined, ~user notation is allowed and the string is inserted
  47  * after ~user/.  E.g. a request to git://host/~alice/frotz would
  48  * go to /home/alice/pub_git/frotz with --user-path=pub_git.
  49  */
  50 static const char *user_path;
  51
  52 /* Timeout, and initial timeout */
  53 static unsigned int timeout;
  54 static unsigned int init_timeout;
  55
  56 struct hostinfo {
  57         struct strbuf hostname;
  58         struct strbuf canon_hostname;
  59         struct strbuf ip_address;
  60         struct strbuf tcp_port;
  61         unsigned int hostname_lookup_done:1;
  62         unsigned int saw_extended_args:1;
  63 };
  64
  65 static void lookup_hostname(struct hostinfo *hi);
  66
  67 static const char *get_canon_hostname(struct hostinfo *hi)
  68 {
  69         lookup_hostname(hi);
  70         return hi->canon_hostname.buf;
  71 }
  72
  73 static const char *get_ip_address(struct hostinfo *hi)
  74 {
  75         lookup_hostname(hi);
  76         return hi->ip_address.buf;
  77 }
  78
  79 static void logreport(int priority, const char *err, va_list params)
  80 {
  81         if (log_syslog) {
  82                 char buf[1024];
  83                 vsnprintf(buf, sizeof(buf), err, params);
  84                 syslog(priority, "%s", buf);
  85         } else {
  86                 /*
  87                  * Since stderr is set to buffered mode, the
  88                  * logging of different processes will not overlap
  89                  * unless they overflow the (rather big) buffers.
  90                  */
  91                 fprintf(stderr, "[%"PRIuMAX"] ", (uintmax_t)getpid());
  92                 vfprintf(stderr, err, params);
  93                 fputc('\n', stderr);
  94                 fflush(stderr);
  95         }
  96 }
  97
  98 __attribute__((format (printf, 1, 2)))
  99 static void logerror(const char *err, ...)
 100 {
 101         va_list params;
 102         va_start(params, err);
 103         logreport(LOG_ERR, err, params);
 104         va_end(params);
 105 }
 106
 107 __attribute__((format (printf, 1, 2)))
 108 static void loginfo(const char *err, ...)
 109 {
 110         va_list params;
 111         if (!verbose)
 112                 return;
 113         va_start(params, err);
 114         logreport(LOG_INFO, err, params);
 115         va_end(params);
 116 }
 117
 118 static void NORETURN daemon_die(const char *err, va_list params)
 119 {
 120         logreport(LOG_ERR, err, params);
 121         exit(1);
 122 }
 123
 124 struct expand_path_context {
 125         const char *directory;
 126         struct hostinfo *hostinfo;
 127 };
 128
 129 static size_t expand_path(struct strbuf *sb, const char *placeholder, void *ctx)
 130 {
 131         struct expand_path_context *context = ctx;
 132         struct hostinfo *hi = context->hostinfo;
 133
 134         switch (placeholder[0]) {
 135         case 'H':
 136                 strbuf_addbuf(sb, &hi->hostname);
 137                 return 1;
 138         case 'C':
 139                 if (placeholder[1] == 'H') {
 140                         strbuf_addstr(sb, get_canon_hostname(hi));
 141                         return 2;
 142                 }
 143                 break;
 144         case 'I':
 145                 if (placeholder[1] == 'P') {
 146                         strbuf_addstr(sb, get_ip_address(hi));
 147                         return 2;
 148                 }
 149                 break;
 150         case 'P':
 151                 strbuf_addbuf(sb, &hi->tcp_port);
 152                 return 1;
 153         case 'D':
 154                 strbuf_addstr(sb, context->directory);
 155                 return 1;
 156         }
 157         return 0;
 158 }
 159
 160 static const char *path_ok(const char *directory, struct hostinfo *hi)
 161 {
 162         static char rpath[PATH_MAX];
 163         static char interp_path[PATH_MAX];
 164         const char *path;
 165         const char *dir;
 166
 167         dir = directory;
 168
 169         if (daemon_avoid_alias(dir)) {
 170                 logerror("'%s': aliased", dir);
 171                 return NULL;
 172         }
 173
 174         if (*dir == '~') {
 175                 if (!user_path) {
 176                         logerror("'%s': User-path not allowed", dir);
 177                         return NULL;
 178                 }
 179                 if (*user_path) {
 180                         /* Got either "~alice" or "~alice/foo";
 181                          * rewrite them to "~alice/%s" or
 182                          * "~alice/%s/foo".
 183                          */
 184                         int namlen, restlen = strlen(dir);
 185                         const char *slash = strchr(dir, '/');
 186                         if (!slash)
 187                                 slash = dir + restlen;
 188                         namlen = slash - dir;
 189                         restlen -= namlen;
 190                         loginfo("userpath <%s>, request <%s>, namlen %d, restlen %d, slash <%s>", user_path, dir, namlen, restlen, slash);
 191                         snprintf(rpath, PATH_MAX, "%.*s/%s%.*s",
 192                                  namlen, dir, user_path, restlen, slash);
 193                         dir = rpath;
 194                 }
 195         }
 196         else if (interpolated_path && hi->saw_extended_args) {
 197                 struct strbuf expanded_path = STRBUF_INIT;
 198                 struct expand_path_context context;
 199
 200                 context.directory = directory;
 201                 context.hostinfo = hi;
 202
 203                 if (*dir != '/') {
 204                         /* Allow only absolute */
 205                         logerror("'%s': Non-absolute path denied (interpolated-path active)", dir);
 206                         return NULL;
 207                 }
 208
 209                 strbuf_expand(&expanded_path, interpolated_path,
 210                               expand_path, &context);
 211                 strlcpy(interp_path, expanded_path.buf, PATH_MAX);
 212                 strbuf_release(&expanded_path);
 213                 loginfo("Interpolated dir '%s'", interp_path);
 214
 215                 dir = interp_path;
 216         }
 217         else if (base_path) {
 218                 if (*dir != '/') {
 219                         /* Allow only absolute */
 220                         logerror("'%s': Non-absolute path denied (base-path active)", dir);
 221                         return NULL;
 222                 }
 223                 snprintf(rpath, PATH_MAX, "%s%s", base_path, dir);
 224                 dir = rpath;
 225         }
 226
 227         path = enter_repo(dir, strict_paths);
 228         if (!path && base_path && base_path_relaxed) {
 229                 /*
 230                  * if we fail and base_path_relaxed is enabled, try without
 231                  * prefixing the base path
 232                  */
 233                 dir = directory;
 234                 path = enter_repo(dir, strict_paths);
 235         }
 236
 237         if (!path) {
 238                 logerror("'%s' does not appear to be a git repository", dir);
 239                 return NULL;
 240         }
 241
 242         if ( ok_paths && *ok_paths ) {
 243                 char **pp;
 244                 int pathlen = strlen(path);
 245
 246                 /* The validation is done on the paths after enter_repo
 247                  * appends optional {.git,.git/.git} and friends, but
 248                  * it does not use getcwd().  So if your /pub is
 249                  * a symlink to /mnt/pub, you can whitelist /pub and
 250                  * do not have to say /mnt/pub.
 251                  * Do not say /pub/.
 252                  */
 253                 for ( pp = ok_paths ; *pp ; pp++ ) {
 254                         int len = strlen(*pp);
 255                         if (len <= pathlen &&
 256                             !memcmp(*pp, path, len) &&
 257                             (path[len] == '\0' ||
 258                              (!strict_paths && path[len] == '/')))
 259                                 return path;
 260                 }
 261         }
 262         else {
 263                 /* be backwards compatible */
 264                 if (!strict_paths)
 265                         return path;
 266         }
 267
 268         logerror("'%s': not in whitelist", path);
 269         return NULL;            /* Fallthrough. Deny by default */
 270 }
 271
 272 typedef int (*daemon_service_fn)(void);
 273 struct daemon_service {
 274         const char *name;
 275         const char *config_name;
 276         daemon_service_fn fn;
 277         int enabled;
 278         int overridable;
 279 };
 280
 281 static int daemon_error(const char *dir, const char *msg)
 282 {
 283         if (!informative_errors)
 284                 msg = "access denied or repository not exported";
 285         packet_write(1, "ERR %s: %s", msg, dir);
 286         return -1;
 287 }
 288
 289 static const char *access_hook;
 290
 291 static int run_access_hook(struct daemon_service *service, const char *dir,
 292                            const char *path, struct hostinfo *hi)
 293 {
 294         struct child_process child = CHILD_PROCESS_INIT;
 295         struct strbuf buf = STRBUF_INIT;
 296         const char *argv[8];
 297         const char **arg = argv;
 298         char *eol;
 299         int seen_errors = 0;
 300
 301         *arg++ = access_hook;
 302         *arg++ = service->name;
 303         *arg++ = path;
 304         *arg++ = hi->hostname.buf;
 305         *arg++ = get_canon_hostname(hi);
 306         *arg++ = get_ip_address(hi);
 307         *arg++ = hi->tcp_port.buf;
 308         *arg = NULL;
 309
 310         child.use_shell = 1;
 311         child.argv = argv;
 312         child.no_stdin = 1;
 313         child.no_stderr = 1;
 314         child.out = -1;
 315         if (start_command(&child)) {
 316                 logerror("daemon access hook '%s' failed to start",
 317                          access_hook);
 318                 goto error_return;
 319         }
 320         if (strbuf_read(&buf, child.out, 0) < 0) {
 321                 logerror("failed to read from pipe to daemon access hook '%s'",
 322                          access_hook);
 323                 strbuf_reset(&buf);
 324                 seen_errors = 1;
 325         }
 326         if (close(child.out) < 0) {
 327                 logerror("failed to close pipe to daemon access hook '%s'",
 328                          access_hook);
 329                 seen_errors = 1;
 330         }
 331         if (finish_command(&child))
 332                 seen_errors = 1;
 333
 334         if (!seen_errors) {
 335                 strbuf_release(&buf);
 336                 return 0;
 337         }
 338
 339 error_return:
 340         strbuf_ltrim(&buf);
 341         if (!buf.len)
 342                 strbuf_addstr(&buf, "service rejected");
 343         eol = strchr(buf.buf, '\n');
 344         if (eol)
 345                 *eol = '\0';
 346         errno = EACCES;
 347         daemon_error(dir, buf.buf);
 348         strbuf_release(&buf);
 349         return -1;
 350 }
 351
 352 static int run_service(const char *dir, struct daemon_service *service,
 353                        struct hostinfo *hi)
 354 {
 355         const char *path;
 356         int enabled = service->enabled;
 357         struct strbuf var = STRBUF_INIT;
 358
 359         loginfo("Request %s for '%s'", service->name, dir);
 360
 361         if (!enabled && !service->overridable) {
 362                 logerror("'%s': service not enabled.", service->name);
 363                 errno = EACCES;
 364                 return daemon_error(dir, "service not enabled");
 365         }
 366
 367         if (!(path = path_ok(dir, hi)))
 368                 return daemon_error(dir, "no such repository");
 369
 370         /*
 371          * Security on the cheap.
 372          *
 373          * We want a readable HEAD, usable "objects" directory, and
 374          * a "git-daemon-export-ok" flag that says that the other side
 375          * is ok with us doing this.
 376          *
 377          * path_ok() uses enter_repo() and does whitelist checking.
 378          * We only need to make sure the repository is exported.
 379          */
 380
 381         if (!export_all_trees && access("git-daemon-export-ok", F_OK)) {
 382                 logerror("'%s': repository not exported.", path);
 383                 errno = EACCES;
 384                 return daemon_error(dir, "repository not exported");
 385         }
 386
 387         if (service->overridable) {
 388                 strbuf_addf(&var, "daemon.%s", service->config_name);
 389                 git_config_get_bool(var.buf, &enabled);
 390                 strbuf_release(&var);
 391         }
 392         if (!enabled) {
 393                 logerror("'%s': service not enabled for '%s'",
 394                          service->name, path);
 395                 errno = EACCES;
 396                 return daemon_error(dir, "service not enabled");
 397         }
 398
 399         /*
 400          * Optionally, a hook can choose to deny access to the
 401          * repository depending on the phase of the moon.
 402          */
 403         if (access_hook && run_access_hook(service, dir, path, hi))
 404                 return -1;
 405
 406         /*
 407          * We'll ignore SIGTERM from now on, we have a
 408          * good client.
 409          */
 410         signal(SIGTERM, SIG_IGN);
 411
 412         return service->fn();
 413 }
 414
 415 static void copy_to_log(int fd)
 416 {
 417         struct strbuf line = STRBUF_INIT;
 418         FILE *fp;
 419
 420         fp = fdopen(fd, "r");
 421         if (fp == NULL) {
 422                 logerror("fdopen of error channel failed");
 423                 close(fd);
 424                 return;
 425         }
 426
 427         while (strbuf_getline(&line, fp, '\n') != EOF) {
 428                 logerror("%s", line.buf);
 429                 strbuf_setlen(&line, 0);
 430         }
 431
 432         strbuf_release(&line);
 433         fclose(fp);
 434 }
 435
 436 static int run_service_command(const char **argv)
 437 {
 438         struct child_process cld = CHILD_PROCESS_INIT;
 439
 440         cld.argv = argv;
 441         cld.git_cmd = 1;
 442         cld.err = -1;
 443         if (start_command(&cld))
 444                 return -1;
 445
 446         close(0);
 447         close(1);
 448
 449         copy_to_log(cld.err);
 450
 451         return finish_command(&cld);
 452 }
 453
 454 static int upload_pack(void)
 455 {
 456         /* Timeout as string */
 457         char timeout_buf[64];
 458         const char *argv[] = { "upload-pack", "--strict", NULL, ".", NULL };
 459
 460         argv[2] = timeout_buf;
 461
 462         snprintf(timeout_buf, sizeof timeout_buf, "--timeout=%u", timeout);
 463         return run_service_command(argv);
 464 }
 465
 466 static int upload_archive(void)
 467 {
 468         static const char *argv[] = { "upload-archive", ".", NULL };
 469         return run_service_command(argv);
 470 }
 471
 472 static int receive_pack(void)
 473 {
 474         static const char *argv[] = { "receive-pack", ".", NULL };
 475         return run_service_command(argv);
 476 }
 477
 478 static struct daemon_service daemon_service[] = {
 479         { "upload-archive", "uploadarch", upload_archive, 0, 1 },
 480         { "upload-pack", "uploadpack", upload_pack, 1, 1 },
 481         { "receive-pack", "receivepack", receive_pack, 0, 1 },
 482 };
 483
 484 static void enable_service(const char *name, int ena)
 485 {
 486         int i;
 487         for (i = 0; i < ARRAY_SIZE(daemon_service); i++) {
 488                 if (!strcmp(daemon_service[i].name, name)) {
 489                         daemon_service[i].enabled = ena;
 490                         return;
 491                 }
 492         }
 493         die("No such service %s", name);
 494 }
 495
 496 static void make_service_overridable(const char *name, int ena)
 497 {
 498         int i;
 499         for (i = 0; i < ARRAY_SIZE(daemon_service); i++) {
 500                 if (!strcmp(daemon_service[i].name, name)) {
 501                         daemon_service[i].overridable = ena;
 502                         return;
 503                 }
 504         }
 505         die("No such service %s", name);
 506 }
 507
 508 static void parse_host_and_port(char *hostport, char **host,
 509         char **port)
 510 {
 511         if (*hostport == '[') {
 512                 char *end;
 513
 514                 end = strchr(hostport, ']');
 515                 if (!end)
 516                         die("Invalid request ('[' without ']')");
 517                 *end = '\0';
 518                 *host = hostport + 1;
 519                 if (!end[1])
 520                         *port = NULL;
 521                 else if (end[1] == ':')
 522                         *port = end + 2;
 523                 else
 524                         die("Garbage after end of host part");
 525         } else {
 526                 *host = hostport;
 527                 *port = strrchr(hostport, ':');
 528                 if (*port) {
 529                         **port = '\0';
 530                         ++*port;
 531                 }
 532         }
 533 }
 534
 535 /*
 536  * Sanitize a string from the client so that it's OK to be inserted into a
 537  * filesystem path. Specifically, we disallow slashes, runs of "..", and
 538  * trailing and leading dots, which means that the client cannot escape
 539  * our base path via ".." traversal.
 540  */
 541 static void sanitize_client(struct strbuf *out, const char *in)
 542 {
 543         for (; *in; in++) {
 544                 if (*in == '/')
 545                         continue;
 546                 if (*in == '.' && (!out->len || out->buf[out->len - 1] == '.'))
 547                         continue;
 548                 strbuf_addch(out, *in);
 549         }
 550
 551         while (out->len && out->buf[out->len - 1] == '.')
 552                 strbuf_setlen(out, out->len - 1);
 553 }
 554
 555 /*
 556  * Like sanitize_client, but we also perform any canonicalization
 557  * to make life easier on the admin.
 558  */
 559 static void canonicalize_client(struct strbuf *out, const char *in)
 560 {
 561         sanitize_client(out, in);
 562         strbuf_tolower(out);
 563 }
 564
 565 /*
 566  * Read the host as supplied by the client connection.
 567  */
 568 static void parse_host_arg(struct hostinfo *hi, char *extra_args, int buflen)
 569 {
 570         char *val;
 571         int vallen;
 572         char *end = extra_args + buflen;
 573
 574         if (extra_args < end && *extra_args) {
 575                 hi->saw_extended_args = 1;
 576                 if (strncasecmp("host=", extra_args, 5) == 0) {
 577                         val = extra_args + 5;
 578                         vallen = strlen(val) + 1;
 579                         if (*val) {
 580                                 /* Split <host>:<port> at colon. */
 581                                 char *host;
 582                                 char *port;
 583                                 parse_host_and_port(val, &host, &port);
 584                                 if (port)
 585                                         sanitize_client(&hi->tcp_port, port);
 586                                 canonicalize_client(&hi->hostname, host);
 587                                 hi->hostname_lookup_done = 0;
 588                         }
 589
 590                         /* On to the next one */
 591                         extra_args = val + vallen;
 592                 }
 593                 if (extra_args < end && *extra_args)
 594                         die("Invalid request");
 595         }
 596 }
 597
 598 /*
 599  * Locate canonical hostname and its IP address.
 600  */
 601 static void lookup_hostname(struct hostinfo *hi)
 602 {
 603         if (!hi->hostname_lookup_done && hi->hostname.len) {
 604 #ifndef NO_IPV6
 605                 struct addrinfo hints;
 606                 struct addrinfo *ai;
 607                 int gai;
 608                 static char addrbuf[HOST_NAME_MAX + 1];
 609
 610                 memset(&hints, 0, sizeof(hints));
 611                 hints.ai_flags = AI_CANONNAME;
 612
 613                 gai = getaddrinfo(hi->hostname.buf, NULL, &hints, &ai);
 614                 if (!gai) {
 615                         struct sockaddr_in *sin_addr = (void *)ai->ai_addr;
 616
 617                         inet_ntop(AF_INET, &sin_addr->sin_addr,
 618                                   addrbuf, sizeof(addrbuf));
 619                         strbuf_addstr(&hi->ip_address, addrbuf);
 620
 621                         if (ai->ai_canonname)
 622                                 sanitize_client(&hi->canon_hostname,
 623                                                 ai->ai_canonname);
 624                         else
 625                                 strbuf_addbuf(&hi->canon_hostname,
 626                                               &hi->ip_address);
 627
 628                         freeaddrinfo(ai);
 629                 }
 630 #else
 631                 struct hostent *hent;
 632                 struct sockaddr_in sa;
 633                 char **ap;
 634                 static char addrbuf[HOST_NAME_MAX + 1];
 635
 636                 hent = gethostbyname(hi->hostname.buf);
 637                 if (hent) {
 638                         ap = hent->h_addr_list;
 639                         memset(&sa, 0, sizeof sa);
 640                         sa.sin_family = hent->h_addrtype;
 641                         sa.sin_port = htons(0);
 642                         memcpy(&sa.sin_addr, *ap, hent->h_length);
 643
 644                         inet_ntop(hent->h_addrtype, &sa.sin_addr,
 645                                   addrbuf, sizeof(addrbuf));
 646
 647                         sanitize_client(&hi->canon_hostname, hent->h_name);
 648                         strbuf_addstr(&hi->ip_address, addrbuf);
 649                 }
 650 #endif
 651                 hi->hostname_lookup_done = 1;
 652         }
 653 }
 654
 655 static void hostinfo_init(struct hostinfo *hi)
 656 {
 657         memset(hi, 0, sizeof(*hi));
 658         strbuf_init(&hi->hostname, 0);
 659         strbuf_init(&hi->canon_hostname, 0);
 660         strbuf_init(&hi->ip_address, 0);
 661         strbuf_init(&hi->tcp_port, 0);
 662 }
 663
 664 static void hostinfo_clear(struct hostinfo *hi)
 665 {
 666         strbuf_release(&hi->hostname);
 667         strbuf_release(&hi->canon_hostname);
 668         strbuf_release(&hi->ip_address);
 669         strbuf_release(&hi->tcp_port);
 670 }
 671
 672 static int execute(void)
 673 {
 674         char *line = packet_buffer;
 675         int pktlen, len, i;
 676         char *addr = getenv("REMOTE_ADDR"), *port = getenv("REMOTE_PORT");
 677         struct hostinfo hi;
 678
 679         hostinfo_init(&hi);
 680
 681         if (addr)
 682                 loginfo("Connection from %s:%s", addr, port);
 683
 684         alarm(init_timeout ? init_timeout : timeout);
 685         pktlen = packet_read(0, NULL, NULL, packet_buffer, sizeof(packet_buffer), 0);
 686         alarm(0);
 687
 688         len = strlen(line);
 689         if (pktlen != len)
 690                 loginfo("Extended attributes (%d bytes) exist <%.*s>",
 691                         (int) pktlen - len,
 692                         (int) pktlen - len, line + len + 1);
 693         if (len && line[len-1] == '\n') {
 694                 line[--len] = 0;
 695                 pktlen--;
 696         }
 697
 698         if (len != pktlen)
 699                 parse_host_arg(&hi, line + len + 1, pktlen - len - 1);
 700
 701         for (i = 0; i < ARRAY_SIZE(daemon_service); i++) {
 702                 struct daemon_service *s = &(daemon_service[i]);
 703                 const char *arg;
 704
 705                 if (skip_prefix(line, "git-", &arg) &&
 706                     skip_prefix(arg, s->name, &arg) &&
 707                     *arg++ == ' ') {
 708                         /*
 709                          * Note: The directory here is probably context sensitive,
 710                          * and might depend on the actual service being performed.
 711                          */
 712                         int rc = run_service(arg, s, &hi);
 713                         hostinfo_clear(&hi);
 714                         return rc;
 715                 }
 716         }
 717
 718         hostinfo_clear(&hi);
 719         logerror("Protocol error: '%s'", line);
 720         return -1;
 721 }
 722
 723 static int addrcmp(const struct sockaddr_storage *s1,
 724     const struct sockaddr_storage *s2)
 725 {
 726         const struct sockaddr *sa1 = (const struct sockaddr*) s1;
 727         const struct sockaddr *sa2 = (const struct sockaddr*) s2;
 728
 729         if (sa1->sa_family != sa2->sa_family)
 730                 return sa1->sa_family - sa2->sa_family;
 731         if (sa1->sa_family == AF_INET)
 732                 return memcmp(&((struct sockaddr_in *)s1)->sin_addr,
 733                     &((struct sockaddr_in *)s2)->sin_addr,
 734                     sizeof(struct in_addr));
 735 #ifndef NO_IPV6
 736         if (sa1->sa_family == AF_INET6)
 737                 return memcmp(&((struct sockaddr_in6 *)s1)->sin6_addr,
 738                     &((struct sockaddr_in6 *)s2)->sin6_addr,
 739                     sizeof(struct in6_addr));
 740 #endif
 741         return 0;
 742 }
 743
 744 static int max_connections = 32;
 745
 746 static unsigned int live_children;
 747
 748 static struct child {
 749         struct child *next;
 750         struct child_process cld;
 751         struct sockaddr_storage address;
 752 } *firstborn;
 753
 754 static void add_child(struct child_process *cld, struct sockaddr *addr, socklen_t addrlen)
 755 {
 756         struct child *newborn, **cradle;
 757
 758         newborn = xcalloc(1, sizeof(*newborn));
 759         live_children++;
 760         memcpy(&newborn->cld, cld, sizeof(*cld));
 761         memcpy(&newborn->address, addr, addrlen);
 762         for (cradle = &firstborn; *cradle; cradle = &(*cradle)->next)
 763                 if (!addrcmp(&(*cradle)->address, &newborn->address))
 764                         break;
 765         newborn->next = *cradle;
 766         *cradle = newborn;
 767 }
 768
 769 /*
 770  * This gets called if the number of connections grows
 771  * past "max_connections".
 772  *
 773  * We kill the newest connection from a duplicate IP.
 774  */
 775 static void kill_some_child(void)
 776 {
 777         const struct child *blanket, *next;
 778
 779         if (!(blanket = firstborn))
 780                 return;
 781
 782         for (; (next = blanket->next); blanket = next)
 783                 if (!addrcmp(&blanket->address, &next->address)) {
 784                         kill(blanket->cld.pid, SIGTERM);
 785                         break;
 786                 }
 787 }
 788
 789 static void check_dead_children(void)
 790 {
 791         int status;
 792         pid_t pid;
 793
 794         struct child **cradle, *blanket;
 795         for (cradle = &firstborn; (blanket = *cradle);)
 796                 if ((pid = waitpid(blanket->cld.pid, &status, WNOHANG)) > 1) {
 797                         const char *dead = "";
 798                         if (status)
 799                                 dead = " (with error)";
 800                         loginfo("[%"PRIuMAX"] Disconnected%s", (uintmax_t)pid, dead);
 801
 802                         /* remove the child */
 803                         *cradle = blanket->next;
 804                         live_children--;
 805                         free(blanket);
 806                 } else
 807                         cradle = &blanket->next;
 808 }
 809
 810 static char **cld_argv;
 811 static void handle(int incoming, struct sockaddr *addr, socklen_t addrlen)
 812 {
 813         struct child_process cld = CHILD_PROCESS_INIT;
 814         char addrbuf[300] = "REMOTE_ADDR=", portbuf[300];
 815         char *env[] = { addrbuf, portbuf, NULL };
 816
 817         if (max_connections && live_children >= max_connections) {
 818                 kill_some_child();
 819                 sleep(1);  /* give it some time to die */
 820                 check_dead_children();
 821                 if (live_children >= max_connections) {
 822                         close(incoming);
 823                         logerror("Too many children, dropping connection");
 824                         return;
 825                 }
 826         }
 827
 828         if (addr->sa_family == AF_INET) {
 829                 struct sockaddr_in *sin_addr = (void *) addr;
 830                 inet_ntop(addr->sa_family, &sin_addr->sin_addr, addrbuf + 12,
 831                     sizeof(addrbuf) - 12);
 832                 snprintf(portbuf, sizeof(portbuf), "REMOTE_PORT=%d",
 833                     ntohs(sin_addr->sin_port));
 834 #ifndef NO_IPV6
 835         } else if (addr->sa_family == AF_INET6) {
 836                 struct sockaddr_in6 *sin6_addr = (void *) addr;
 837
 838                 char *buf = addrbuf + 12;
 839                 *buf++ = '['; *buf = '\0'; /* stpcpy() is cool */
 840                 inet_ntop(AF_INET6, &sin6_addr->sin6_addr, buf,
 841                     sizeof(addrbuf) - 13);
 842                 strcat(buf, "]");
 843
 844                 snprintf(portbuf, sizeof(portbuf), "REMOTE_PORT=%d",
 845                     ntohs(sin6_addr->sin6_port));
 846 #endif
 847         }
 848
 849         cld.env = (const char **)env;
 850         cld.argv = (const char **)cld_argv;
 851         cld.in = incoming;
 852         cld.out = dup(incoming);
 853
 854         if (start_command(&cld))
 855                 logerror("unable to fork");
 856         else
 857                 add_child(&cld, addr, addrlen);
 858 }
 859
 860 static void child_handler(int signo)
 861 {
 862         /*
 863          * Otherwise empty handler because systemcalls will get interrupted
 864          * upon signal receipt
 865          * SysV needs the handler to be rearmed
 866          */
 867         signal(SIGCHLD, child_handler);
 868 }
 869
 870 static int set_reuse_addr(int sockfd)
 871 {
 872         int on = 1;
 873
 874         if (!reuseaddr)
 875                 return 0;
 876         return setsockopt(sockfd, SOL_SOCKET, SO_REUSEADDR,
 877                           &on, sizeof(on));
 878 }
 879
 880 struct socketlist {
 881         int *list;
 882         size_t nr;
 883         size_t alloc;
 884 };
 885
 886 static const char *ip2str(int family, struct sockaddr *sin, socklen_t len)
 887 {
 888 #ifdef NO_IPV6
 889         static char ip[INET_ADDRSTRLEN];
 890 #else
 891         static char ip[INET6_ADDRSTRLEN];
 892 #endif
 893
 894         switch (family) {
 895 #ifndef NO_IPV6
 896         case AF_INET6:
 897                 inet_ntop(family, &((struct sockaddr_in6*)sin)->sin6_addr, ip, len);
 898                 break;
 899 #endif
 900         case AF_INET:
 901                 inet_ntop(family, &((struct sockaddr_in*)sin)->sin_addr, ip, len);
 902                 break;
 903         default:
 904                 strcpy(ip, "<unknown>");
 905         }
 906         return ip;
 907 }
 908
 909 #ifndef NO_IPV6
 910
 911 static int setup_named_sock(char *listen_addr, int listen_port, struct socketlist *socklist)
 912 {
 913         int socknum = 0;
 914         char pbuf[NI_MAXSERV];
 915         struct addrinfo hints, *ai0, *ai;
 916         int gai;
 917         long flags;
 918
 919         sprintf(pbuf, "%d", listen_port);
 920         memset(&hints, 0, sizeof(hints));
 921         hints.ai_family = AF_UNSPEC;
 922         hints.ai_socktype = SOCK_STREAM;
 923         hints.ai_protocol = IPPROTO_TCP;
 924         hints.ai_flags = AI_PASSIVE;
 925
 926         gai = getaddrinfo(listen_addr, pbuf, &hints, &ai0);
 927         if (gai) {
 928                 logerror("getaddrinfo() for %s failed: %s", listen_addr, gai_strerror(gai));
 929                 return 0;
 930         }
 931
 932         for (ai = ai0; ai; ai = ai->ai_next) {
 933                 int sockfd;
 934
 935                 sockfd = socket(ai->ai_family, ai->ai_socktype, ai->ai_protocol);
 936                 if (sockfd < 0)
 937                         continue;
 938                 if (sockfd >= FD_SETSIZE) {
 939                         logerror("Socket descriptor too large");
 940                         close(sockfd);
 941                         continue;
 942                 }
 943
 944 #ifdef IPV6_V6ONLY
 945                 if (ai->ai_family == AF_INET6) {
 946                         int on = 1;
 947                         setsockopt(sockfd, IPPROTO_IPV6, IPV6_V6ONLY,
 948                                    &on, sizeof(on));
 949                         /* Note: error is not fatal */
 950                 }
 951 #endif
 952
 953                 if (set_reuse_addr(sockfd)) {
 954                         logerror("Could not set SO_REUSEADDR: %s", strerror(errno));
 955                         close(sockfd);
 956                         continue;
 957                 }
 958
 959                 if (bind(sockfd, ai->ai_addr, ai->ai_addrlen) < 0) {
 960                         logerror("Could not bind to %s: %s",
 961                                  ip2str(ai->ai_family, ai->ai_addr, ai->ai_addrlen),
 962                                  strerror(errno));
 963                         close(sockfd);
 964                         continue;       /* not fatal */
 965                 }
 966                 if (listen(sockfd, 5) < 0) {
 967                         logerror("Could not listen to %s: %s",
 968                                  ip2str(ai->ai_family, ai->ai_addr, ai->ai_addrlen),
 969                                  strerror(errno));
 970                         close(sockfd);
 971                         continue;       /* not fatal */
 972                 }
 973
 974                 flags = fcntl(sockfd, F_GETFD, 0);
 975                 if (flags >= 0)
 976                         fcntl(sockfd, F_SETFD, flags | FD_CLOEXEC);
 977
 978                 ALLOC_GROW(socklist->list, socklist->nr + 1, socklist->alloc);
 979                 socklist->list[socklist->nr++] = sockfd;
 980                 socknum++;
 981         }
 982
 983         freeaddrinfo(ai0);
 984
 985         return socknum;
 986 }
 987
 988 #else /* NO_IPV6 */
 989
 990 static int setup_named_sock(char *listen_addr, int listen_port, struct socketlist *socklist)
 991 {
 992         struct sockaddr_in sin;
 993         int sockfd;
 994         long flags;
 995
 996         memset(&sin, 0, sizeof sin);
 997         sin.sin_family = AF_INET;
 998         sin.sin_port = htons(listen_port);
 999
1000         if (listen_addr) {
1001                 /* Well, host better be an IP address here. */
1002                 if (inet_pton(AF_INET, listen_addr, &sin.sin_addr.s_addr) <= 0)
1003                         return 0;
1004         } else {
1005                 sin.sin_addr.s_addr = htonl(INADDR_ANY);
1006         }
1007
1008         sockfd = socket(AF_INET, SOCK_STREAM, 0);
1009         if (sockfd < 0)
1010                 return 0;
1011
1012         if (set_reuse_addr(sockfd)) {
1013                 logerror("Could not set SO_REUSEADDR: %s", strerror(errno));
1014                 close(sockfd);
1015                 return 0;
1016         }
1017
1018         if ( bind(sockfd, (struct sockaddr *)&sin, sizeof sin) < 0 ) {
1019                 logerror("Could not bind to %s: %s",
1020                          ip2str(AF_INET, (struct sockaddr *)&sin, sizeof(sin)),
1021                          strerror(errno));
1022                 close(sockfd);
1023                 return 0;
1024         }
1025
1026         if (listen(sockfd, 5) < 0) {
1027                 logerror("Could not listen to %s: %s",
1028                          ip2str(AF_INET, (struct sockaddr *)&sin, sizeof(sin)),
1029                          strerror(errno));
1030                 close(sockfd);
1031                 return 0;
1032         }
1033
1034         flags = fcntl(sockfd, F_GETFD, 0);
1035         if (flags >= 0)
1036                 fcntl(sockfd, F_SETFD, flags | FD_CLOEXEC);
1037
1038         ALLOC_GROW(socklist->list, socklist->nr + 1, socklist->alloc);
1039         socklist->list[socklist->nr++] = sockfd;
1040         return 1;
1041 }
1042
1043 #endif
1044
1045 static void socksetup(struct string_list *listen_addr, int listen_port, struct socketlist *socklist)
1046 {
1047         if (!listen_addr->nr)
1048                 setup_named_sock(NULL, listen_port, socklist);
1049         else {
1050                 int i, socknum;
1051                 for (i = 0; i < listen_addr->nr; i++) {
1052                         socknum = setup_named_sock(listen_addr->items[i].string,
1053                                                    listen_port, socklist);
1054
1055                         if (socknum == 0)
1056                                 logerror("unable to allocate any listen sockets for host %s on port %u",
1057                                          listen_addr->items[i].string, listen_port);
1058                 }
1059         }
1060 }
1061
1062 static int service_loop(struct socketlist *socklist)
1063 {
1064         struct pollfd *pfd;
1065         int i;
1066
1067         pfd = xcalloc(socklist->nr, sizeof(struct pollfd));
1068
1069         for (i = 0; i < socklist->nr; i++) {
1070                 pfd[i].fd = socklist->list[i];
1071                 pfd[i].events = POLLIN;
1072         }
1073
1074         signal(SIGCHLD, child_handler);
1075
1076         for (;;) {
1077                 int i;
1078
1079                 check_dead_children();
1080
1081                 if (poll(pfd, socklist->nr, -1) < 0) {
1082                         if (errno != EINTR) {
1083                                 logerror("Poll failed, resuming: %s",
1084                                       strerror(errno));
1085                                 sleep(1);
1086                         }
1087                         continue;
1088                 }
1089
1090                 for (i = 0; i < socklist->nr; i++) {
1091                         if (pfd[i].revents & POLLIN) {
1092                                 union {
1093                                         struct sockaddr sa;
1094                                         struct sockaddr_in sai;
1095 #ifndef NO_IPV6
1096                                         struct sockaddr_in6 sai6;
1097 #endif
1098                                 } ss;
1099                                 socklen_t sslen = sizeof(ss);
1100                                 int incoming = accept(pfd[i].fd, &ss.sa, &sslen);
1101                                 if (incoming < 0) {
1102                                         switch (errno) {
1103                                         case EAGAIN:
1104                                         case EINTR:
1105                                         case ECONNABORTED:
1106                                                 continue;
1107                                         default:
1108                                                 die_errno("accept returned");
1109                                         }
1110                                 }
1111                                 handle(incoming, &ss.sa, sslen);
1112                         }
1113                 }
1114         }
1115 }
1116
1117 #ifdef NO_POSIX_GOODIES
1118
1119 struct credentials;
1120
1121 static void drop_privileges(struct credentials *cred)
1122 {
1123         /* nothing */
1124 }
1125
1126 static struct credentials *prepare_credentials(const char *user_name,
1127     const char *group_name)
1128 {
1129         die("--user not supported on this platform");
1130 }
1131
1132 #else
1133
1134 struct credentials {
1135         struct passwd *pass;
1136         gid_t gid;
1137 };
1138
1139 static void drop_privileges(struct credentials *cred)
1140 {
1141         if (cred && (initgroups(cred->pass->pw_name, cred->gid) ||
1142             setgid (cred->gid) || setuid(cred->pass->pw_uid)))
1143                 die("cannot drop privileges");
1144 }
1145
1146 static struct credentials *prepare_credentials(const char *user_name,
1147     const char *group_name)
1148 {
1149         static struct credentials c;
1150
1151         c.pass = getpwnam(user_name);
1152         if (!c.pass)
1153                 die("user not found - %s", user_name);
1154
1155         if (!group_name)
1156                 c.gid = c.pass->pw_gid;
1157         else {
1158                 struct group *group = getgrnam(group_name);
1159                 if (!group)
1160                         die("group not found - %s", group_name);
1161
1162                 c.gid = group->gr_gid;
1163         }
1164
1165         return &c;
1166 }
1167 #endif
1168
1169 static int serve(struct string_list *listen_addr, int listen_port,
1170     struct credentials *cred)
1171 {
1172         struct socketlist socklist = { NULL, 0, 0 };
1173
1174         socksetup(listen_addr, listen_port, &socklist);
1175         if (socklist.nr == 0)
1176                 die("unable to allocate any listen sockets on port %u",
1177                     listen_port);
1178
1179         drop_privileges(cred);
1180
1181         loginfo("Ready to rumble");
1182
1183         return service_loop(&socklist);
1184 }
1185
1186 int main(int argc, char **argv)
1187 {
1188         int listen_port = 0;
1189         struct string_list listen_addr = STRING_LIST_INIT_NODUP;
1190         int serve_mode = 0, inetd_mode = 0;
1191         const char *pid_file = NULL, *user_name = NULL, *group_name = NULL;
1192         int detach = 0;
1193         struct credentials *cred = NULL;
1194         int i;
1195
1196         git_setup_gettext();
1197
1198         git_extract_argv0_path(argv[0]);
1199
1200         for (i = 1; i < argc; i++) {
1201                 char *arg = argv[i];
1202                 const char *v;
1203
1204                 if (skip_prefix(arg, "--listen=", &v)) {
1205                         string_list_append(&listen_addr, xstrdup_tolower(v));
1206                         continue;
1207                 }
1208                 if (skip_prefix(arg, "--port=", &v)) {
1209                         char *end;
1210                         unsigned long n;
1211                         n = strtoul(v, &end, 0);
1212                         if (*v && !*end) {
1213                                 listen_port = n;
1214                                 continue;
1215                         }
1216                 }
1217                 if (!strcmp(arg, "--serve")) {
1218                         serve_mode = 1;
1219                         continue;
1220                 }
1221                 if (!strcmp(arg, "--inetd")) {
1222                         inetd_mode = 1;
1223                         log_syslog = 1;
1224                         continue;
1225                 }
1226                 if (!strcmp(arg, "--verbose")) {
1227                         verbose = 1;
1228                         continue;
1229                 }
1230                 if (!strcmp(arg, "--syslog")) {
1231                         log_syslog = 1;
1232                         continue;
1233                 }
1234                 if (!strcmp(arg, "--export-all")) {
1235                         export_all_trees = 1;
1236                         continue;
1237                 }
1238                 if (skip_prefix(arg, "--access-hook=", &v)) {
1239                         access_hook = v;
1240                         continue;
1241                 }
1242                 if (skip_prefix(arg, "--timeout=", &v)) {
1243                         timeout = atoi(v);
1244                         continue;
1245                 }
1246                 if (skip_prefix(arg, "--init-timeout=", &v)) {
1247                         init_timeout = atoi(v);
1248                         continue;
1249                 }
1250                 if (skip_prefix(arg, "--max-connections=", &v)) {
1251                         max_connections = atoi(v);
1252                         if (max_connections < 0)
1253                                 max_connections = 0;            /* unlimited */
1254                         continue;
1255                 }
1256                 if (!strcmp(arg, "--strict-paths")) {
1257                         strict_paths = 1;
1258                         continue;
1259                 }
1260                 if (skip_prefix(arg, "--base-path=", &v)) {
1261                         base_path = v;
1262                         continue;
1263                 }
1264                 if (!strcmp(arg, "--base-path-relaxed")) {
1265                         base_path_relaxed = 1;
1266                         continue;
1267                 }
1268                 if (skip_prefix(arg, "--interpolated-path=", &v)) {
1269                         interpolated_path = v;
1270                         continue;
1271                 }
1272                 if (!strcmp(arg, "--reuseaddr")) {
1273                         reuseaddr = 1;
1274                         continue;
1275                 }
1276                 if (!strcmp(arg, "--user-path")) {
1277                         user_path = "";
1278                         continue;
1279                 }
1280                 if (skip_prefix(arg, "--user-path=", &v)) {
1281                         user_path = v;
1282                         continue;
1283                 }
1284                 if (skip_prefix(arg, "--pid-file=", &v)) {
1285                         pid_file = v;
1286                         continue;
1287                 }
1288                 if (!strcmp(arg, "--detach")) {
1289                         detach = 1;
1290                         log_syslog = 1;
1291                         continue;
1292                 }
1293                 if (skip_prefix(arg, "--user=", &v)) {
1294                         user_name = v;
1295                         continue;
1296                 }
1297                 if (skip_prefix(arg, "--group=", &v)) {
1298                         group_name = v;
1299                         continue;
1300                 }
1301                 if (skip_prefix(arg, "--enable=", &v)) {
1302                         enable_service(v, 1);
1303                         continue;
1304                 }
1305                 if (skip_prefix(arg, "--disable=", &v)) {
1306                         enable_service(v, 0);
1307                         continue;
1308                 }
1309                 if (skip_prefix(arg, "--allow-override=", &v)) {
1310                         make_service_overridable(v, 1);
1311                         continue;
1312                 }
1313                 if (skip_prefix(arg, "--forbid-override=", &v)) {
1314                         make_service_overridable(v, 0);
1315                         continue;
1316                 }
1317                 if (!strcmp(arg, "--informative-errors")) {
1318                         informative_errors = 1;
1319                         continue;
1320                 }
1321                 if (!strcmp(arg, "--no-informative-errors")) {
1322                         informative_errors = 0;
1323                         continue;
1324                 }
1325                 if (!strcmp(arg, "--")) {
1326                         ok_paths = &argv[i+1];
1327                         break;
1328                 } else if (arg[0] != '-') {
1329                         ok_paths = &argv[i];
1330                         break;
1331                 }
1332
1333                 usage(daemon_usage);
1334         }
1335
1336         if (log_syslog) {
1337                 openlog("git-daemon", LOG_PID, LOG_DAEMON);
1338                 set_die_routine(daemon_die);
1339         } else
1340                 /* avoid splitting a message in the middle */
1341                 setvbuf(stderr, NULL, _IOFBF, 4096);
1342
1343         if (inetd_mode && (detach || group_name || user_name))
1344                 die("--detach, --user and --group are incompatible with --inetd");
1345
1346         if (inetd_mode && (listen_port || (listen_addr.nr > 0)))
1347                 die("--listen= and --port= are incompatible with --inetd");
1348         else if (listen_port == 0)
1349                 listen_port = DEFAULT_GIT_PORT;
1350
1351         if (group_name && !user_name)
1352                 die("--group supplied without --user");
1353
1354         if (user_name)
1355                 cred = prepare_credentials(user_name, group_name);
1356
1357         if (strict_paths && (!ok_paths || !*ok_paths))
1358                 die("option --strict-paths requires a whitelist");
1359
1360         if (base_path && !is_directory(base_path))
1361                 die("base-path '%s' does not exist or is not a directory",
1362                     base_path);
1363
1364         if (inetd_mode) {
1365                 if (!freopen("/dev/null", "w", stderr))
1366                         die_errno("failed to redirect stderr to /dev/null");
1367         }
1368
1369         if (inetd_mode || serve_mode)
1370                 return execute();
1371
1372         if (detach) {
1373                 if (daemonize())
1374                         die("--detach not supported on this platform");
1375         } else
1376                 sanitize_stdfds();
1377
1378         if (pid_file)
1379                 write_file(pid_file, 1, "%"PRIuMAX"\n", (uintmax_t) getpid());
1380
1381         /* prepare argv for serving-processes */
1382         cld_argv = xmalloc(sizeof (char *) * (argc + 2));
1383         cld_argv[0] = argv[0];  /* git-daemon */
1384         cld_argv[1] = "--serve";
1385         for (i = 1; i < argc; ++i)
1386                 cld_argv[i+1] = argv[i];
1387         cld_argv[argc+1] = NULL;
1388
1389         return serve(&listen_addr, listen_port, cred);
1390 }