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