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