daemon.c

   1 #include "cache.h"
   2 #include "pkt-line.h"
   3 #include "exec_cmd.h"
   4
   5 #include <syslog.h>
   6
   7 #ifndef HOST_NAME_MAX
   8 #define HOST_NAME_MAX 256
   9 #endif
  10
  11 #ifndef NI_MAXSERV
  12 #define NI_MAXSERV 32
  13 #endif
  14
  15 static int log_syslog;
  16 static int verbose;
  17 static int reuseaddr;
  18
  19 static const char daemon_usage[] =
  20 "git daemon [--verbose] [--syslog] [--export-all]\n"
  21 "           [--timeout=n] [--init-timeout=n] [--max-connections=n]\n"
  22 "           [--strict-paths] [--base-path=path] [--base-path-relaxed]\n"
  23 "           [--user-path | --user-path=path]\n"
  24 "           [--interpolated-path=path]\n"
  25 "           [--reuseaddr] [--detach] [--pid-file=file]\n"
  26 "           [--[enable|disable|allow-override|forbid-override]=service]\n"
  27 "           [--inetd | [--listen=host_or_ipaddr] [--port=n]\n"
  28 "                      [--user=user [--group=group]]\n"
  29 "           [directory...]";
  30
  31 /* List of acceptable pathname prefixes */
  32 static char **ok_paths;
  33 static int strict_paths;
  34
  35 /* If this is set, git-daemon-export-ok is not required */
  36 static int export_all_trees;
  37
  38 /* Take all paths relative to this one if non-NULL */
  39 static char *base_path;
  40 static char *interpolated_path;
  41 static int base_path_relaxed;
  42
  43 /* Flag indicating client sent extra args. */
  44 static int saw_extended_args;
  45
  46 /* If defined, ~user notation is allowed and the string is inserted
  47  * after ~user/.  E.g. a request to git://host/~alice/frotz would
  48  * go to /home/alice/pub_git/frotz with --user-path=pub_git.
  49  */
  50 static const char *user_path;
  51
  52 /* Timeout, and initial timeout */
  53 static unsigned int timeout;
  54 static unsigned int init_timeout;
  55
  56 static char *hostname;
  57 static char *canon_hostname;
  58 static char *ip_address;
  59 static char *tcp_port;
  60 static char *directory;
  61
  62 static void logreport(int priority, const char *err, va_list params)
  63 {
  64         if (log_syslog) {
  65                 char buf[1024];
  66                 vsnprintf(buf, sizeof(buf), err, params);
  67                 syslog(priority, "%s", buf);
  68         } else {
  69                 /*
  70                  * Since stderr is set to linebuffered mode, the
  71                  * logging of different processes will not overlap
  72                  */
  73                 fprintf(stderr, "[%"PRIuMAX"] ", (uintmax_t)getpid());
  74                 vfprintf(stderr, err, params);
  75                 fputc('\n', stderr);
  76         }
  77 }
  78
  79 static void logerror(const char *err, ...)
  80 {
  81         va_list params;
  82         va_start(params, err);
  83         logreport(LOG_ERR, err, params);
  84         va_end(params);
  85 }
  86
  87 static void loginfo(const char *err, ...)
  88 {
  89         va_list params;
  90         if (!verbose)
  91                 return;
  92         va_start(params, err);
  93         logreport(LOG_INFO, err, params);
  94         va_end(params);
  95 }
  96
  97 static void NORETURN daemon_die(const char *err, va_list params)
  98 {
  99         logreport(LOG_ERR, err, params);
 100         exit(1);
 101 }
 102
 103 static int avoid_alias(char *p)
 104 {
 105         int sl, ndot;
 106
 107         /*
 108          * This resurrects the belts and suspenders paranoia check by HPA
 109          * done in <435560F7.4080006@zytor.com> thread, now enter_repo()
 110          * does not do getcwd() based path canonicalizations.
 111          *
 112          * sl becomes true immediately after seeing '/' and continues to
 113          * be true as long as dots continue after that without intervening
 114          * non-dot character.
 115          */
 116         if (!p || (*p != '/' && *p != '~'))
 117                 return -1;
 118         sl = 1; ndot = 0;
 119         p++;
 120
 121         while (1) {
 122                 char ch = *p++;
 123                 if (sl) {
 124                         if (ch == '.')
 125                                 ndot++;
 126                         else if (ch == '/') {
 127                                 if (ndot < 3)
 128                                         /* reject //, /./ and /../ */
 129                                         return -1;
 130                                 ndot = 0;
 131                         }
 132                         else if (ch == 0) {
 133                                 if (0 < ndot && ndot < 3)
 134                                         /* reject /.$ and /..$ */
 135                                         return -1;
 136                                 return 0;
 137                         }
 138                         else
 139                                 sl = ndot = 0;
 140                 }
 141                 else if (ch == 0)
 142                         return 0;
 143                 else if (ch == '/') {
 144                         sl = 1;
 145                         ndot = 0;
 146                 }
 147         }
 148 }
 149
 150 static char *path_ok(void)
 151 {
 152         static char rpath[PATH_MAX];
 153         static char interp_path[PATH_MAX];
 154         int retried_path = 0;
 155         char *path;
 156         char *dir;
 157
 158         dir = directory;
 159
 160         if (avoid_alias(dir)) {
 161                 logerror("'%s': aliased", dir);
 162                 return NULL;
 163         }
 164
 165         if (*dir == '~') {
 166                 if (!user_path) {
 167                         logerror("'%s': User-path not allowed", dir);
 168                         return NULL;
 169                 }
 170                 if (*user_path) {
 171                         /* Got either "~alice" or "~alice/foo";
 172                          * rewrite them to "~alice/%s" or
 173                          * "~alice/%s/foo".
 174                          */
 175                         int namlen, restlen = strlen(dir);
 176                         char *slash = strchr(dir, '/');
 177                         if (!slash)
 178                                 slash = dir + restlen;
 179                         namlen = slash - dir;
 180                         restlen -= namlen;
 181                         loginfo("userpath <%s>, request <%s>, namlen %d, restlen %d, slash <%s>", user_path, dir, namlen, restlen, slash);
 182                         snprintf(rpath, PATH_MAX, "%.*s/%s%.*s",
 183                                  namlen, dir, user_path, restlen, slash);
 184                         dir = rpath;
 185                 }
 186         }
 187         else if (interpolated_path && saw_extended_args) {
 188                 struct strbuf expanded_path = STRBUF_INIT;
 189                 struct strbuf_expand_dict_entry dict[] = {
 190                         { "H", hostname },
 191                         { "CH", canon_hostname },
 192                         { "IP", ip_address },
 193                         { "P", tcp_port },
 194                         { "D", directory },
 195                         { "%", "%" },
 196                         { NULL }
 197                 };
 198
 199                 if (*dir != '/') {
 200                         /* Allow only absolute */
 201                         logerror("'%s': Non-absolute path denied (interpolated-path active)", dir);
 202                         return NULL;
 203                 }
 204
 205                 strbuf_expand(&expanded_path, interpolated_path,
 206                                 strbuf_expand_dict_cb, &dict);
 207                 strlcpy(interp_path, expanded_path.buf, PATH_MAX);
 208                 strbuf_release(&expanded_path);
 209                 loginfo("Interpolated dir '%s'", interp_path);
 210
 211                 dir = interp_path;
 212         }
 213         else if (base_path) {
 214                 if (*dir != '/') {
 215                         /* Allow only absolute */
 216                         logerror("'%s': Non-absolute path denied (base-path active)", dir);
 217                         return NULL;
 218                 }
 219                 snprintf(rpath, PATH_MAX, "%s%s", base_path, dir);
 220                 dir = rpath;
 221         }
 222
 223         do {
 224                 path = enter_repo(dir, strict_paths);
 225                 if (path)
 226                         break;
 227
 228                 /*
 229                  * if we fail and base_path_relaxed is enabled, try without
 230                  * prefixing the base path
 231                  */
 232                 if (base_path && base_path_relaxed && !retried_path) {
 233                         dir = directory;
 234                         retried_path = 1;
 235                         continue;
 236                 }
 237                 break;
 238         } while (1);
 239
 240         if (!path) {
 241                 logerror("'%s': unable to chdir or not a git archive", dir);
 242                 return NULL;
 243         }
 244
 245         if ( ok_paths && *ok_paths ) {
 246                 char **pp;
 247                 int pathlen = strlen(path);
 248
 249                 /* The validation is done on the paths after enter_repo
 250                  * appends optional {.git,.git/.git} and friends, but
 251                  * it does not use getcwd().  So if your /pub is
 252                  * a symlink to /mnt/pub, you can whitelist /pub and
 253                  * do not have to say /mnt/pub.
 254                  * Do not say /pub/.
 255                  */
 256                 for ( pp = ok_paths ; *pp ; pp++ ) {
 257                         int len = strlen(*pp);
 258                         if (len <= pathlen &&
 259                             !memcmp(*pp, path, len) &&
 260                             (path[len] == '\0' ||
 261                              (!strict_paths && path[len] == '/')))
 262                                 return path;
 263                 }
 264         }
 265         else {
 266                 /* be backwards compatible */
 267                 if (!strict_paths)
 268                         return path;
 269         }
 270
 271         logerror("'%s': not in whitelist", path);
 272         return NULL;            /* Fallthrough. Deny by default */
 273 }
 274
 275 typedef int (*daemon_service_fn)(void);
 276 struct daemon_service {
 277         const char *name;
 278         const char *config_name;
 279         daemon_service_fn fn;
 280         int enabled;
 281         int overridable;
 282 };
 283
 284 static struct daemon_service *service_looking_at;
 285 static int service_enabled;
 286
 287 static int git_daemon_config(const char *var, const char *value, void *cb)
 288 {
 289         if (!prefixcmp(var, "daemon.") &&
 290             !strcmp(var + 7, service_looking_at->config_name)) {
 291                 service_enabled = git_config_bool(var, value);
 292                 return 0;
 293         }
 294
 295         /* we are not interested in parsing any other configuration here */
 296         return 0;
 297 }
 298
 299 static int run_service(struct daemon_service *service)
 300 {
 301         const char *path;
 302         int enabled = service->enabled;
 303
 304         loginfo("Request %s for '%s'", service->name, directory);
 305
 306         if (!enabled && !service->overridable) {
 307                 logerror("'%s': service not enabled.", service->name);
 308                 errno = EACCES;
 309                 return -1;
 310         }
 311
 312         if (!(path = path_ok()))
 313                 return -1;
 314
 315         /*
 316          * Security on the cheap.
 317          *
 318          * We want a readable HEAD, usable "objects" directory, and
 319          * a "git-daemon-export-ok" flag that says that the other side
 320          * is ok with us doing this.
 321          *
 322          * path_ok() uses enter_repo() and does whitelist checking.
 323          * We only need to make sure the repository is exported.
 324          */
 325
 326         if (!export_all_trees && access("git-daemon-export-ok", F_OK)) {
 327                 logerror("'%s': repository not exported.", path);
 328                 errno = EACCES;
 329                 return -1;
 330         }
 331
 332         if (service->overridable) {
 333                 service_looking_at = service;
 334                 service_enabled = -1;
 335                 git_config(git_daemon_config, NULL);
 336                 if (0 <= service_enabled)
 337                         enabled = service_enabled;
 338         }
 339         if (!enabled) {
 340                 logerror("'%s': service not enabled for '%s'",
 341                          service->name, path);
 342                 errno = EACCES;
 343                 return -1;
 344         }
 345
 346         /*
 347          * We'll ignore SIGTERM from now on, we have a
 348          * good client.
 349          */
 350         signal(SIGTERM, SIG_IGN);
 351
 352         return service->fn();
 353 }
 354
 355 static int upload_pack(void)
 356 {
 357         /* Timeout as string */
 358         char timeout_buf[64];
 359
 360         snprintf(timeout_buf, sizeof timeout_buf, "--timeout=%u", timeout);
 361
 362         /* git-upload-pack only ever reads stuff, so this is safe */
 363         execl_git_cmd("upload-pack", "--strict", timeout_buf, ".", NULL);
 364         return -1;
 365 }
 366
 367 static int upload_archive(void)
 368 {
 369         execl_git_cmd("upload-archive", ".", NULL);
 370         return -1;
 371 }
 372
 373 static int receive_pack(void)
 374 {
 375         execl_git_cmd("receive-pack", ".", NULL);
 376         return -1;
 377 }
 378
 379 static struct daemon_service daemon_service[] = {
 380         { "upload-archive", "uploadarch", upload_archive, 0, 1 },
 381         { "upload-pack", "uploadpack", upload_pack, 1, 1 },
 382         { "receive-pack", "receivepack", receive_pack, 0, 1 },
 383 };
 384
 385 static void enable_service(const char *name, int ena)
 386 {
 387         int i;
 388         for (i = 0; i < ARRAY_SIZE(daemon_service); i++) {
 389                 if (!strcmp(daemon_service[i].name, name)) {
 390                         daemon_service[i].enabled = ena;
 391                         return;
 392                 }
 393         }
 394         die("No such service %s", name);
 395 }
 396
 397 static void make_service_overridable(const char *name, int ena)
 398 {
 399         int i;
 400         for (i = 0; i < ARRAY_SIZE(daemon_service); i++) {
 401                 if (!strcmp(daemon_service[i].name, name)) {
 402                         daemon_service[i].overridable = ena;
 403                         return;
 404                 }
 405         }
 406         die("No such service %s", name);
 407 }
 408
 409 /*
 410  * Separate the "extra args" information as supplied by the client connection.
 411  */
 412 static void parse_extra_args(char *extra_args, int buflen)
 413 {
 414         char *val;
 415         int vallen;
 416         char *end = extra_args + buflen;
 417         char *hp;
 418
 419         while (extra_args < end && *extra_args) {
 420                 saw_extended_args = 1;
 421                 if (strncasecmp("host=", extra_args, 5) == 0) {
 422                         val = extra_args + 5;
 423                         vallen = strlen(val) + 1;
 424                         if (*val) {
 425                                 /* Split <host>:<port> at colon. */
 426                                 char *host = val;
 427                                 char *port = strrchr(host, ':');
 428                                 if (port) {
 429                                         *port = 0;
 430                                         port++;
 431                                         free(tcp_port);
 432                                         tcp_port = xstrdup(port);
 433                                 }
 434                                 free(hostname);
 435                                 hostname = xstrdup(host);
 436                         }
 437
 438                         /* On to the next one */
 439                         extra_args = val + vallen;
 440                 }
 441         }
 442
 443         /*
 444          * Replace literal host with lowercase-ized hostname.
 445          */
 446         hp = hostname;
 447         if (!hp)
 448                 return;
 449         for ( ; *hp; hp++)
 450                 *hp = tolower(*hp);
 451
 452         /*
 453          * Locate canonical hostname and its IP address.
 454          */
 455 #ifndef NO_IPV6
 456         {
 457                 struct addrinfo hints;
 458                 struct addrinfo *ai, *ai0;
 459                 int gai;
 460                 static char addrbuf[HOST_NAME_MAX + 1];
 461
 462                 memset(&hints, 0, sizeof(hints));
 463                 hints.ai_flags = AI_CANONNAME;
 464
 465                 gai = getaddrinfo(hostname, 0, &hints, &ai0);
 466                 if (!gai) {
 467                         for (ai = ai0; ai; ai = ai->ai_next) {
 468                                 struct sockaddr_in *sin_addr = (void *)ai->ai_addr;
 469
 470                                 inet_ntop(AF_INET, &sin_addr->sin_addr,
 471                                           addrbuf, sizeof(addrbuf));
 472                                 free(canon_hostname);
 473                                 canon_hostname = xstrdup(ai->ai_canonname);
 474                                 free(ip_address);
 475                                 ip_address = xstrdup(addrbuf);
 476                                 break;
 477                         }
 478                         freeaddrinfo(ai0);
 479                 }
 480         }
 481 #else
 482         {
 483                 struct hostent *hent;
 484                 struct sockaddr_in sa;
 485                 char **ap;
 486                 static char addrbuf[HOST_NAME_MAX + 1];
 487
 488                 hent = gethostbyname(hostname);
 489
 490                 ap = hent->h_addr_list;
 491                 memset(&sa, 0, sizeof sa);
 492                 sa.sin_family = hent->h_addrtype;
 493                 sa.sin_port = htons(0);
 494                 memcpy(&sa.sin_addr, *ap, hent->h_length);
 495
 496                 inet_ntop(hent->h_addrtype, &sa.sin_addr,
 497                           addrbuf, sizeof(addrbuf));
 498
 499                 free(canon_hostname);
 500                 canon_hostname = xstrdup(hent->h_name);
 501                 free(ip_address);
 502                 ip_address = xstrdup(addrbuf);
 503         }
 504 #endif
 505 }
 506
 507
 508 static int execute(struct sockaddr *addr)
 509 {
 510         static char line[1000];
 511         int pktlen, len, i;
 512
 513         if (addr) {
 514                 char addrbuf[256] = "";
 515                 int port = -1;
 516
 517                 if (addr->sa_family == AF_INET) {
 518                         struct sockaddr_in *sin_addr = (void *) addr;
 519                         inet_ntop(addr->sa_family, &sin_addr->sin_addr, addrbuf, sizeof(addrbuf));
 520                         port = ntohs(sin_addr->sin_port);
 521 #ifndef NO_IPV6
 522                 } else if (addr && addr->sa_family == AF_INET6) {
 523                         struct sockaddr_in6 *sin6_addr = (void *) addr;
 524
 525                         char *buf = addrbuf;
 526                         *buf++ = '['; *buf = '\0'; /* stpcpy() is cool */
 527                         inet_ntop(AF_INET6, &sin6_addr->sin6_addr, buf, sizeof(addrbuf) - 1);
 528                         strcat(buf, "]");
 529
 530                         port = ntohs(sin6_addr->sin6_port);
 531 #endif
 532                 }
 533                 loginfo("Connection from %s:%d", addrbuf, port);
 534                 setenv("REMOTE_ADDR", addrbuf, 1);
 535         }
 536         else {
 537                 unsetenv("REMOTE_ADDR");
 538         }
 539
 540         alarm(init_timeout ? init_timeout : timeout);
 541         pktlen = packet_read_line(0, line, sizeof(line));
 542         alarm(0);
 543
 544         len = strlen(line);
 545         if (pktlen != len)
 546                 loginfo("Extended attributes (%d bytes) exist <%.*s>",
 547                         (int) pktlen - len,
 548                         (int) pktlen - len, line + len + 1);
 549         if (len && line[len-1] == '\n') {
 550                 line[--len] = 0;
 551                 pktlen--;
 552         }
 553
 554         free(hostname);
 555         free(canon_hostname);
 556         free(ip_address);
 557         free(tcp_port);
 558         free(directory);
 559         hostname = canon_hostname = ip_address = tcp_port = directory = NULL;
 560
 561         if (len != pktlen)
 562                 parse_extra_args(line + len + 1, pktlen - len - 1);
 563
 564         for (i = 0; i < ARRAY_SIZE(daemon_service); i++) {
 565                 struct daemon_service *s = &(daemon_service[i]);
 566                 int namelen = strlen(s->name);
 567                 if (!prefixcmp(line, "git-") &&
 568                     !strncmp(s->name, line + 4, namelen) &&
 569                     line[namelen + 4] == ' ') {
 570                         /*
 571                          * Note: The directory here is probably context sensitive,
 572                          * and might depend on the actual service being performed.
 573                          */
 574                         free(directory);
 575                         directory = xstrdup(line + namelen + 5);
 576                         return run_service(s);
 577                 }
 578         }
 579
 580         logerror("Protocol error: '%s'", line);
 581         return -1;
 582 }
 583
 584 static int max_connections = 32;
 585
 586 static unsigned int live_children;
 587
 588 static struct child {
 589         struct child *next;
 590         pid_t pid;
 591         struct sockaddr_storage address;
 592 } *firstborn;
 593
 594 static void add_child(pid_t pid, struct sockaddr *addr, int addrlen)
 595 {
 596         struct child *newborn, **cradle;
 597
 598         /*
 599          * This must be xcalloc() -- we'll compare the whole sockaddr_storage
 600          * but individual address may be shorter.
 601          */
 602         newborn = xcalloc(1, sizeof(*newborn));
 603         live_children++;
 604         newborn->pid = pid;
 605         memcpy(&newborn->address, addr, addrlen);
 606         for (cradle = &firstborn; *cradle; cradle = &(*cradle)->next)
 607                 if (!memcmp(&(*cradle)->address, &newborn->address,
 608                             sizeof(newborn->address)))
 609                         break;
 610         newborn->next = *cradle;
 611         *cradle = newborn;
 612 }
 613
 614 static void remove_child(pid_t pid)
 615 {
 616         struct child **cradle, *blanket;
 617
 618         for (cradle = &firstborn; (blanket = *cradle); cradle = &blanket->next)
 619                 if (blanket->pid == pid) {
 620                         *cradle = blanket->next;
 621                         live_children--;
 622                         free(blanket);
 623                         break;
 624                 }
 625 }
 626
 627 /*
 628  * This gets called if the number of connections grows
 629  * past "max_connections".
 630  *
 631  * We kill the newest connection from a duplicate IP.
 632  */
 633 static void kill_some_child(void)
 634 {
 635         const struct child *blanket, *next;
 636
 637         if (!(blanket = firstborn))
 638                 return;
 639
 640         for (; (next = blanket->next); blanket = next)
 641                 if (!memcmp(&blanket->address, &next->address,
 642                             sizeof(next->address))) {
 643                         kill(blanket->pid, SIGTERM);
 644                         break;
 645                 }
 646 }
 647
 648 static void check_dead_children(void)
 649 {
 650         int status;
 651         pid_t pid;
 652
 653         while ((pid = waitpid(-1, &status, WNOHANG)) > 0) {
 654                 const char *dead = "";
 655                 remove_child(pid);
 656                 if (!WIFEXITED(status) || (WEXITSTATUS(status) > 0))
 657                         dead = " (with error)";
 658                 loginfo("[%"PRIuMAX"] Disconnected%s", (uintmax_t)pid, dead);
 659         }
 660 }
 661
 662 static void handle(int incoming, struct sockaddr *addr, int addrlen)
 663 {
 664         pid_t pid;
 665
 666         if (max_connections && live_children >= max_connections) {
 667                 kill_some_child();
 668                 sleep(1);  /* give it some time to die */
 669                 check_dead_children();
 670                 if (live_children >= max_connections) {
 671                         close(incoming);
 672                         logerror("Too many children, dropping connection");
 673                         return;
 674                 }
 675         }
 676
 677         if ((pid = fork())) {
 678                 close(incoming);
 679                 if (pid < 0) {
 680                         logerror("Couldn't fork %s", strerror(errno));
 681                         return;
 682                 }
 683
 684                 add_child(pid, addr, addrlen);
 685                 return;
 686         }
 687
 688         dup2(incoming, 0);
 689         dup2(incoming, 1);
 690         close(incoming);
 691
 692         exit(execute(addr));
 693 }
 694
 695 static void child_handler(int signo)
 696 {
 697         /*
 698          * Otherwise empty handler because systemcalls will get interrupted
 699          * upon signal receipt
 700          * SysV needs the handler to be rearmed
 701          */
 702         signal(SIGCHLD, child_handler);
 703 }
 704
 705 static int set_reuse_addr(int sockfd)
 706 {
 707         int on = 1;
 708
 709         if (!reuseaddr)
 710                 return 0;
 711         return setsockopt(sockfd, SOL_SOCKET, SO_REUSEADDR,
 712                           &on, sizeof(on));
 713 }
 714
 715 #ifndef NO_IPV6
 716
 717 static int socksetup(char *listen_addr, int listen_port, int **socklist_p)
 718 {
 719         int socknum = 0, *socklist = NULL;
 720         int maxfd = -1;
 721         char pbuf[NI_MAXSERV];
 722         struct addrinfo hints, *ai0, *ai;
 723         int gai;
 724         long flags;
 725
 726         sprintf(pbuf, "%d", listen_port);
 727         memset(&hints, 0, sizeof(hints));
 728         hints.ai_family = AF_UNSPEC;
 729         hints.ai_socktype = SOCK_STREAM;
 730         hints.ai_protocol = IPPROTO_TCP;
 731         hints.ai_flags = AI_PASSIVE;
 732
 733         gai = getaddrinfo(listen_addr, pbuf, &hints, &ai0);
 734         if (gai)
 735                 die("getaddrinfo() failed: %s\n", gai_strerror(gai));
 736
 737         for (ai = ai0; ai; ai = ai->ai_next) {
 738                 int sockfd;
 739
 740                 sockfd = socket(ai->ai_family, ai->ai_socktype, ai->ai_protocol);
 741                 if (sockfd < 0)
 742                         continue;
 743                 if (sockfd >= FD_SETSIZE) {
 744                         logerror("Socket descriptor too large");
 745                         close(sockfd);
 746                         continue;
 747                 }
 748
 749 #ifdef IPV6_V6ONLY
 750                 if (ai->ai_family == AF_INET6) {
 751                         int on = 1;
 752                         setsockopt(sockfd, IPPROTO_IPV6, IPV6_V6ONLY,
 753                                    &on, sizeof(on));
 754                         /* Note: error is not fatal */
 755                 }
 756 #endif
 757
 758                 if (set_reuse_addr(sockfd)) {
 759                         close(sockfd);
 760                         continue;
 761                 }
 762
 763                 if (bind(sockfd, ai->ai_addr, ai->ai_addrlen) < 0) {
 764                         close(sockfd);
 765                         continue;       /* not fatal */
 766                 }
 767                 if (listen(sockfd, 5) < 0) {
 768                         close(sockfd);
 769                         continue;       /* not fatal */
 770                 }
 771
 772                 flags = fcntl(sockfd, F_GETFD, 0);
 773                 if (flags >= 0)
 774                         fcntl(sockfd, F_SETFD, flags | FD_CLOEXEC);
 775
 776                 socklist = xrealloc(socklist, sizeof(int) * (socknum + 1));
 777                 socklist[socknum++] = sockfd;
 778
 779                 if (maxfd < sockfd)
 780                         maxfd = sockfd;
 781         }
 782
 783         freeaddrinfo(ai0);
 784
 785         *socklist_p = socklist;
 786         return socknum;
 787 }
 788
 789 #else /* NO_IPV6 */
 790
 791 static int socksetup(char *listen_addr, int listen_port, int **socklist_p)
 792 {
 793         struct sockaddr_in sin;
 794         int sockfd;
 795         long flags;
 796
 797         memset(&sin, 0, sizeof sin);
 798         sin.sin_family = AF_INET;
 799         sin.sin_port = htons(listen_port);
 800
 801         if (listen_addr) {
 802                 /* Well, host better be an IP address here. */
 803                 if (inet_pton(AF_INET, listen_addr, &sin.sin_addr.s_addr) <= 0)
 804                         return 0;
 805         } else {
 806                 sin.sin_addr.s_addr = htonl(INADDR_ANY);
 807         }
 808
 809         sockfd = socket(AF_INET, SOCK_STREAM, 0);
 810         if (sockfd < 0)
 811                 return 0;
 812
 813         if (set_reuse_addr(sockfd)) {
 814                 close(sockfd);
 815                 return 0;
 816         }
 817
 818         if ( bind(sockfd, (struct sockaddr *)&sin, sizeof sin) < 0 ) {
 819                 close(sockfd);
 820                 return 0;
 821         }
 822
 823         if (listen(sockfd, 5) < 0) {
 824                 close(sockfd);
 825                 return 0;
 826         }
 827
 828         flags = fcntl(sockfd, F_GETFD, 0);
 829         if (flags >= 0)
 830                 fcntl(sockfd, F_SETFD, flags | FD_CLOEXEC);
 831
 832         *socklist_p = xmalloc(sizeof(int));
 833         **socklist_p = sockfd;
 834         return 1;
 835 }
 836
 837 #endif
 838
 839 static int service_loop(int socknum, int *socklist)
 840 {
 841         struct pollfd *pfd;
 842         int i;
 843
 844         pfd = xcalloc(socknum, sizeof(struct pollfd));
 845
 846         for (i = 0; i < socknum; i++) {
 847                 pfd[i].fd = socklist[i];
 848                 pfd[i].events = POLLIN;
 849         }
 850
 851         signal(SIGCHLD, child_handler);
 852
 853         for (;;) {
 854                 int i;
 855
 856                 check_dead_children();
 857
 858                 if (poll(pfd, socknum, -1) < 0) {
 859                         if (errno != EINTR) {
 860                                 logerror("Poll failed, resuming: %s",
 861                                       strerror(errno));
 862                                 sleep(1);
 863                         }
 864                         continue;
 865                 }
 866
 867                 for (i = 0; i < socknum; i++) {
 868                         if (pfd[i].revents & POLLIN) {
 869                                 struct sockaddr_storage ss;
 870                                 unsigned int sslen = sizeof(ss);
 871                                 int incoming = accept(pfd[i].fd, (struct sockaddr *)&ss, &sslen);
 872                                 if (incoming < 0) {
 873                                         switch (errno) {
 874                                         case EAGAIN:
 875                                         case EINTR:
 876                                         case ECONNABORTED:
 877                                                 continue;
 878                                         default:
 879                                                 die("accept returned %s", strerror(errno));
 880                                         }
 881                                 }
 882                                 handle(incoming, (struct sockaddr *)&ss, sslen);
 883                         }
 884                 }
 885         }
 886 }
 887
 888 /* if any standard file descriptor is missing open it to /dev/null */
 889 static void sanitize_stdfds(void)
 890 {
 891         int fd = open("/dev/null", O_RDWR, 0);
 892         while (fd != -1 && fd < 2)
 893                 fd = dup(fd);
 894         if (fd == -1)
 895                 die("open /dev/null or dup failed: %s", strerror(errno));
 896         if (fd > 2)
 897                 close(fd);
 898 }
 899
 900 static void daemonize(void)
 901 {
 902         switch (fork()) {
 903                 case 0:
 904                         break;
 905                 case -1:
 906                         die("fork failed: %s", strerror(errno));
 907                 default:
 908                         exit(0);
 909         }
 910         if (setsid() == -1)
 911                 die("setsid failed: %s", strerror(errno));
 912         close(0);
 913         close(1);
 914         close(2);
 915         sanitize_stdfds();
 916 }
 917
 918 static void store_pid(const char *path)
 919 {
 920         FILE *f = fopen(path, "w");
 921         if (!f)
 922                 die("cannot open pid file %s: %s", path, strerror(errno));
 923         if (fprintf(f, "%"PRIuMAX"\n", (uintmax_t) getpid()) < 0 || fclose(f) != 0)
 924                 die("failed to write pid file %s: %s", path, strerror(errno));
 925 }
 926
 927 static int serve(char *listen_addr, int listen_port, struct passwd *pass, gid_t gid)
 928 {
 929         int socknum, *socklist;
 930
 931         socknum = socksetup(listen_addr, listen_port, &socklist);
 932         if (socknum == 0)
 933                 die("unable to allocate any listen sockets on host %s port %u",
 934                     listen_addr, listen_port);
 935
 936         if (pass && gid &&
 937             (initgroups(pass->pw_name, gid) || setgid (gid) ||
 938              setuid(pass->pw_uid)))
 939                 die("cannot drop privileges");
 940
 941         return service_loop(socknum, socklist);
 942 }
 943
 944 int main(int argc, char **argv)
 945 {
 946         int listen_port = 0;
 947         char *listen_addr = NULL;
 948         int inetd_mode = 0;
 949         const char *pid_file = NULL, *user_name = NULL, *group_name = NULL;
 950         int detach = 0;
 951         struct passwd *pass = NULL;
 952         struct group *group;
 953         gid_t gid = 0;
 954         int i;
 955
 956         for (i = 1; i < argc; i++) {
 957                 char *arg = argv[i];
 958
 959                 if (!prefixcmp(arg, "--listen=")) {
 960                     char *p = arg + 9;
 961                     char *ph = listen_addr = xmalloc(strlen(arg + 9) + 1);
 962                     while (*p)
 963                         *ph++ = tolower(*p++);
 964                     *ph = 0;
 965                     continue;
 966                 }
 967                 if (!prefixcmp(arg, "--port=")) {
 968                         char *end;
 969                         unsigned long n;
 970                         n = strtoul(arg+7, &end, 0);
 971                         if (arg[7] && !*end) {
 972                                 listen_port = n;
 973                                 continue;
 974                         }
 975                 }
 976                 if (!strcmp(arg, "--inetd")) {
 977                         inetd_mode = 1;
 978                         log_syslog = 1;
 979                         continue;
 980                 }
 981                 if (!strcmp(arg, "--verbose")) {
 982                         verbose = 1;
 983                         continue;
 984                 }
 985                 if (!strcmp(arg, "--syslog")) {
 986                         log_syslog = 1;
 987                         continue;
 988                 }
 989                 if (!strcmp(arg, "--export-all")) {
 990                         export_all_trees = 1;
 991                         continue;
 992                 }
 993                 if (!prefixcmp(arg, "--timeout=")) {
 994                         timeout = atoi(arg+10);
 995                         continue;
 996                 }
 997                 if (!prefixcmp(arg, "--init-timeout=")) {
 998                         init_timeout = atoi(arg+15);
 999                         continue;
1000                 }
1001                 if (!prefixcmp(arg, "--max-connections=")) {
1002                         max_connections = atoi(arg+18);
1003                         if (max_connections < 0)
1004                                 max_connections = 0;            /* unlimited */
1005                         continue;
1006                 }
1007                 if (!strcmp(arg, "--strict-paths")) {
1008                         strict_paths = 1;
1009                         continue;
1010                 }
1011                 if (!prefixcmp(arg, "--base-path=")) {
1012                         base_path = arg+12;
1013                         continue;
1014                 }
1015                 if (!strcmp(arg, "--base-path-relaxed")) {
1016                         base_path_relaxed = 1;
1017                         continue;
1018                 }
1019                 if (!prefixcmp(arg, "--interpolated-path=")) {
1020                         interpolated_path = arg+20;
1021                         continue;
1022                 }
1023                 if (!strcmp(arg, "--reuseaddr")) {
1024                         reuseaddr = 1;
1025                         continue;
1026                 }
1027                 if (!strcmp(arg, "--user-path")) {
1028                         user_path = "";
1029                         continue;
1030                 }
1031                 if (!prefixcmp(arg, "--user-path=")) {
1032                         user_path = arg + 12;
1033                         continue;
1034                 }
1035                 if (!prefixcmp(arg, "--pid-file=")) {
1036                         pid_file = arg + 11;
1037                         continue;
1038                 }
1039                 if (!strcmp(arg, "--detach")) {
1040                         detach = 1;
1041                         log_syslog = 1;
1042                         continue;
1043                 }
1044                 if (!prefixcmp(arg, "--user=")) {
1045                         user_name = arg + 7;
1046                         continue;
1047                 }
1048                 if (!prefixcmp(arg, "--group=")) {
1049                         group_name = arg + 8;
1050                         continue;
1051                 }
1052                 if (!prefixcmp(arg, "--enable=")) {
1053                         enable_service(arg + 9, 1);
1054                         continue;
1055                 }
1056                 if (!prefixcmp(arg, "--disable=")) {
1057                         enable_service(arg + 10, 0);
1058                         continue;
1059                 }
1060                 if (!prefixcmp(arg, "--allow-override=")) {
1061                         make_service_overridable(arg + 17, 1);
1062                         continue;
1063                 }
1064                 if (!prefixcmp(arg, "--forbid-override=")) {
1065                         make_service_overridable(arg + 18, 0);
1066                         continue;
1067                 }
1068                 if (!strcmp(arg, "--")) {
1069                         ok_paths = &argv[i+1];
1070                         break;
1071                 } else if (arg[0] != '-') {
1072                         ok_paths = &argv[i];
1073                         break;
1074                 }
1075
1076                 usage(daemon_usage);
1077         }
1078
1079         if (log_syslog) {
1080                 openlog("git-daemon", LOG_PID, LOG_DAEMON);
1081                 set_die_routine(daemon_die);
1082         } else
1083                 /* avoid splitting a message in the middle */
1084                 setvbuf(stderr, NULL, _IOLBF, 0);
1085
1086         if (inetd_mode && (group_name || user_name))
1087                 die("--user and --group are incompatible with --inetd");
1088
1089         if (inetd_mode && (listen_port || listen_addr))
1090                 die("--listen= and --port= are incompatible with --inetd");
1091         else if (listen_port == 0)
1092                 listen_port = DEFAULT_GIT_PORT;
1093
1094         if (group_name && !user_name)
1095                 die("--group supplied without --user");
1096
1097         if (user_name) {
1098                 pass = getpwnam(user_name);
1099                 if (!pass)
1100                         die("user not found - %s", user_name);
1101
1102                 if (!group_name)
1103                         gid = pass->pw_gid;
1104                 else {
1105                         group = getgrnam(group_name);
1106                         if (!group)
1107                                 die("group not found - %s", group_name);
1108
1109                         gid = group->gr_gid;
1110                 }
1111         }
1112
1113         if (strict_paths && (!ok_paths || !*ok_paths))
1114                 die("option --strict-paths requires a whitelist");
1115
1116         if (base_path && !is_directory(base_path))
1117                 die("base-path '%s' does not exist or is not a directory",
1118                     base_path);
1119
1120         if (inetd_mode) {
1121                 struct sockaddr_storage ss;
1122                 struct sockaddr *peer = (struct sockaddr *)&ss;
1123                 socklen_t slen = sizeof(ss);
1124
1125                 freopen("/dev/null", "w", stderr);
1126
1127                 if (getpeername(0, peer, &slen))
1128                         peer = NULL;
1129
1130                 return execute(peer);
1131         }
1132
1133         if (detach) {
1134                 daemonize();
1135                 loginfo("Ready to rumble");
1136         }
1137         else
1138                 sanitize_stdfds();
1139
1140         if (pid_file)
1141                 store_pid(pid_file);
1142
1143         return serve(listen_addr, listen_port, pass, gid);
1144 }