git.oblomov.eu Git - git/blob - 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
 418         while (extra_args < end && *extra_args) {
 419                 saw_extended_args = 1;
 420                 if (strncasecmp("host=", extra_args, 5) == 0) {
 421                         val = extra_args + 5;
 422                         vallen = strlen(val) + 1;
 423                         if (*val) {
 424                                 /* Split <host>:<port> at colon. */
 425                                 char *host = val;
 426                                 char *port = strrchr(host, ':');
 427                                 if (port) {
 428                                         *port = 0;
 429                                         port++;
 430                                         free(tcp_port);
 431                                         tcp_port = xstrdup(port);
 432                                 }
 433                                 free(hostname);
 434                                 hostname = xstrdup(host);
 435                         }
 436
 437                         /* On to the next one */
 438                         extra_args = val + vallen;
 439                 }
 440         }
 441 }
 442
 443 static void fill_in_extra_table_entries(void)
 444 {
 445         char *hp;
 446
 447         /*
 448          * Replace literal host with lowercase-ized hostname.
 449          */
 450         hp = hostname;
 451         if (!hp)
 452                 return;
 453         for ( ; *hp; hp++)
 454                 *hp = tolower(*hp);
 455
 456         /*
 457          * Locate canonical hostname and its IP address.
 458          */
 459 #ifndef NO_IPV6
 460         {
 461                 struct addrinfo hints;
 462                 struct addrinfo *ai, *ai0;
 463                 int gai;
 464                 static char addrbuf[HOST_NAME_MAX + 1];
 465
 466                 memset(&hints, 0, sizeof(hints));
 467                 hints.ai_flags = AI_CANONNAME;
 468
 469                 gai = getaddrinfo(hostname, 0, &hints, &ai0);
 470                 if (!gai) {
 471                         for (ai = ai0; ai; ai = ai->ai_next) {
 472                                 struct sockaddr_in *sin_addr = (void *)ai->ai_addr;
 473
 474                                 inet_ntop(AF_INET, &sin_addr->sin_addr,
 475                                           addrbuf, sizeof(addrbuf));
 476                                 free(canon_hostname);
 477                                 canon_hostname = xstrdup(ai->ai_canonname);
 478                                 free(ip_address);
 479                                 ip_address = xstrdup(addrbuf);
 480                                 break;
 481                         }
 482                         freeaddrinfo(ai0);
 483                 }
 484         }
 485 #else
 486         {
 487                 struct hostent *hent;
 488                 struct sockaddr_in sa;
 489                 char **ap;
 490                 static char addrbuf[HOST_NAME_MAX + 1];
 491
 492                 hent = gethostbyname(hostname);
 493
 494                 ap = hent->h_addr_list;
 495                 memset(&sa, 0, sizeof sa);
 496                 sa.sin_family = hent->h_addrtype;
 497                 sa.sin_port = htons(0);
 498                 memcpy(&sa.sin_addr, *ap, hent->h_length);
 499
 500                 inet_ntop(hent->h_addrtype, &sa.sin_addr,
 501                           addrbuf, sizeof(addrbuf));
 502
 503                 free(canon_hostname);
 504                 canon_hostname = xstrdup(hent->h_name);
 505                 free(ip_address);
 506                 ip_address = xstrdup(addrbuf);
 507         }
 508 #endif
 509 }
 510
 511
 512 static int execute(struct sockaddr *addr)
 513 {
 514         static char line[1000];
 515         int pktlen, len, i;
 516
 517         if (addr) {
 518                 char addrbuf[256] = "";
 519                 int port = -1;
 520
 521                 if (addr->sa_family == AF_INET) {
 522                         struct sockaddr_in *sin_addr = (void *) addr;
 523                         inet_ntop(addr->sa_family, &sin_addr->sin_addr, addrbuf, sizeof(addrbuf));
 524                         port = ntohs(sin_addr->sin_port);
 525 #ifndef NO_IPV6
 526                 } else if (addr && addr->sa_family == AF_INET6) {
 527                         struct sockaddr_in6 *sin6_addr = (void *) addr;
 528
 529                         char *buf = addrbuf;
 530                         *buf++ = '['; *buf = '\0'; /* stpcpy() is cool */
 531                         inet_ntop(AF_INET6, &sin6_addr->sin6_addr, buf, sizeof(addrbuf) - 1);
 532                         strcat(buf, "]");
 533
 534                         port = ntohs(sin6_addr->sin6_port);
 535 #endif
 536                 }
 537                 loginfo("Connection from %s:%d", addrbuf, port);
 538                 setenv("REMOTE_ADDR", addrbuf, 1);
 539         }
 540         else {
 541                 unsetenv("REMOTE_ADDR");
 542         }
 543
 544         alarm(init_timeout ? init_timeout : timeout);
 545         pktlen = packet_read_line(0, line, sizeof(line));
 546         alarm(0);
 547
 548         len = strlen(line);
 549         if (pktlen != len)
 550                 loginfo("Extended attributes (%d bytes) exist <%.*s>",
 551                         (int) pktlen - len,
 552                         (int) pktlen - len, line + len + 1);
 553         if (len && line[len-1] == '\n') {
 554                 line[--len] = 0;
 555                 pktlen--;
 556         }
 557
 558         free(hostname);
 559         free(canon_hostname);
 560         free(ip_address);
 561         free(tcp_port);
 562         free(directory);
 563         hostname = canon_hostname = ip_address = tcp_port = directory = NULL;
 564
 565         if (len != pktlen) {
 566                 parse_extra_args(line + len + 1, pktlen - len - 1);
 567                 fill_in_extra_table_entries();
 568         }
 569
 570         for (i = 0; i < ARRAY_SIZE(daemon_service); i++) {
 571                 struct daemon_service *s = &(daemon_service[i]);
 572                 int namelen = strlen(s->name);
 573                 if (!prefixcmp(line, "git-") &&
 574                     !strncmp(s->name, line + 4, namelen) &&
 575                     line[namelen + 4] == ' ') {
 576                         /*
 577                          * Note: The directory here is probably context sensitive,
 578                          * and might depend on the actual service being performed.
 579                          */
 580                         free(directory);
 581                         directory = xstrdup(line + namelen + 5);
 582                         return run_service(s);
 583                 }
 584         }
 585
 586         logerror("Protocol error: '%s'", line);
 587         return -1;
 588 }
 589
 590 static int max_connections = 32;
 591
 592 static unsigned int live_children;
 593
 594 static struct child {
 595         struct child *next;
 596         pid_t pid;
 597         struct sockaddr_storage address;
 598 } *firstborn;
 599
 600 static void add_child(pid_t pid, struct sockaddr *addr, int addrlen)
 601 {
 602         struct child *newborn, **cradle;
 603
 604         /*
 605          * This must be xcalloc() -- we'll compare the whole sockaddr_storage
 606          * but individual address may be shorter.
 607          */
 608         newborn = xcalloc(1, sizeof(*newborn));
 609         live_children++;
 610         newborn->pid = pid;
 611         memcpy(&newborn->address, addr, addrlen);
 612         for (cradle = &firstborn; *cradle; cradle = &(*cradle)->next)
 613                 if (!memcmp(&(*cradle)->address, &newborn->address,
 614                             sizeof(newborn->address)))
 615                         break;
 616         newborn->next = *cradle;
 617         *cradle = newborn;
 618 }
 619
 620 static void remove_child(pid_t pid)
 621 {
 622         struct child **cradle, *blanket;
 623
 624         for (cradle = &firstborn; (blanket = *cradle); cradle = &blanket->next)
 625                 if (blanket->pid == pid) {
 626                         *cradle = blanket->next;
 627                         live_children--;
 628                         free(blanket);
 629                         break;
 630                 }
 631 }
 632
 633 /*
 634  * This gets called if the number of connections grows
 635  * past "max_connections".
 636  *
 637  * We kill the newest connection from a duplicate IP.
 638  */
 639 static void kill_some_child(void)
 640 {
 641         const struct child *blanket, *next;
 642
 643         if (!(blanket = firstborn))
 644                 return;
 645
 646         for (; (next = blanket->next); blanket = next)
 647                 if (!memcmp(&blanket->address, &next->address,
 648                             sizeof(next->address))) {
 649                         kill(blanket->pid, SIGTERM);
 650                         break;
 651                 }
 652 }
 653
 654 static void check_dead_children(void)
 655 {
 656         int status;
 657         pid_t pid;
 658
 659         while ((pid = waitpid(-1, &status, WNOHANG)) > 0) {
 660                 const char *dead = "";
 661                 remove_child(pid);
 662                 if (!WIFEXITED(status) || (WEXITSTATUS(status) > 0))
 663                         dead = " (with error)";
 664                 loginfo("[%"PRIuMAX"] Disconnected%s", (uintmax_t)pid, dead);
 665         }
 666 }
 667
 668 static void handle(int incoming, struct sockaddr *addr, int addrlen)
 669 {
 670         pid_t pid;
 671
 672         if (max_connections && live_children >= max_connections) {
 673                 kill_some_child();
 674                 sleep(1);  /* give it some time to die */
 675                 check_dead_children();
 676                 if (live_children >= max_connections) {
 677                         close(incoming);
 678                         logerror("Too many children, dropping connection");
 679                         return;
 680                 }
 681         }
 682
 683         if ((pid = fork())) {
 684                 close(incoming);
 685                 if (pid < 0) {
 686                         logerror("Couldn't fork %s", strerror(errno));
 687                         return;
 688                 }
 689
 690                 add_child(pid, addr, addrlen);
 691                 return;
 692         }
 693
 694         dup2(incoming, 0);
 695         dup2(incoming, 1);
 696         close(incoming);
 697
 698         exit(execute(addr));
 699 }
 700
 701 static void child_handler(int signo)
 702 {
 703         /*
 704          * Otherwise empty handler because systemcalls will get interrupted
 705          * upon signal receipt
 706          * SysV needs the handler to be rearmed
 707          */
 708         signal(SIGCHLD, child_handler);
 709 }
 710
 711 static int set_reuse_addr(int sockfd)
 712 {
 713         int on = 1;
 714
 715         if (!reuseaddr)
 716                 return 0;
 717         return setsockopt(sockfd, SOL_SOCKET, SO_REUSEADDR,
 718                           &on, sizeof(on));
 719 }
 720
 721 #ifndef NO_IPV6
 722
 723 static int socksetup(char *listen_addr, int listen_port, int **socklist_p)
 724 {
 725         int socknum = 0, *socklist = NULL;
 726         int maxfd = -1;
 727         char pbuf[NI_MAXSERV];
 728         struct addrinfo hints, *ai0, *ai;
 729         int gai;
 730         long flags;
 731
 732         sprintf(pbuf, "%d", listen_port);
 733         memset(&hints, 0, sizeof(hints));
 734         hints.ai_family = AF_UNSPEC;
 735         hints.ai_socktype = SOCK_STREAM;
 736         hints.ai_protocol = IPPROTO_TCP;
 737         hints.ai_flags = AI_PASSIVE;
 738
 739         gai = getaddrinfo(listen_addr, pbuf, &hints, &ai0);
 740         if (gai)
 741                 die("getaddrinfo() failed: %s\n", gai_strerror(gai));
 742
 743         for (ai = ai0; ai; ai = ai->ai_next) {
 744                 int sockfd;
 745
 746                 sockfd = socket(ai->ai_family, ai->ai_socktype, ai->ai_protocol);
 747                 if (sockfd < 0)
 748                         continue;
 749                 if (sockfd >= FD_SETSIZE) {
 750                         logerror("Socket descriptor too large");
 751                         close(sockfd);
 752                         continue;
 753                 }
 754
 755 #ifdef IPV6_V6ONLY
 756                 if (ai->ai_family == AF_INET6) {
 757                         int on = 1;
 758                         setsockopt(sockfd, IPPROTO_IPV6, IPV6_V6ONLY,
 759                                    &on, sizeof(on));
 760                         /* Note: error is not fatal */
 761                 }
 762 #endif
 763
 764                 if (set_reuse_addr(sockfd)) {
 765                         close(sockfd);
 766                         continue;
 767                 }
 768
 769                 if (bind(sockfd, ai->ai_addr, ai->ai_addrlen) < 0) {
 770                         close(sockfd);
 771                         continue;       /* not fatal */
 772                 }
 773                 if (listen(sockfd, 5) < 0) {
 774                         close(sockfd);
 775                         continue;       /* not fatal */
 776                 }
 777
 778                 flags = fcntl(sockfd, F_GETFD, 0);
 779                 if (flags >= 0)
 780                         fcntl(sockfd, F_SETFD, flags | FD_CLOEXEC);
 781
 782                 socklist = xrealloc(socklist, sizeof(int) * (socknum + 1));
 783                 socklist[socknum++] = sockfd;
 784
 785                 if (maxfd < sockfd)
 786                         maxfd = sockfd;
 787         }
 788
 789         freeaddrinfo(ai0);
 790
 791         *socklist_p = socklist;
 792         return socknum;
 793 }
 794
 795 #else /* NO_IPV6 */
 796
 797 static int socksetup(char *listen_addr, int listen_port, int **socklist_p)
 798 {
 799         struct sockaddr_in sin;
 800         int sockfd;
 801         long flags;
 802
 803         memset(&sin, 0, sizeof sin);
 804         sin.sin_family = AF_INET;
 805         sin.sin_port = htons(listen_port);
 806
 807         if (listen_addr) {
 808                 /* Well, host better be an IP address here. */
 809                 if (inet_pton(AF_INET, listen_addr, &sin.sin_addr.s_addr) <= 0)
 810                         return 0;
 811         } else {
 812                 sin.sin_addr.s_addr = htonl(INADDR_ANY);
 813         }
 814
 815         sockfd = socket(AF_INET, SOCK_STREAM, 0);
 816         if (sockfd < 0)
 817                 return 0;
 818
 819         if (set_reuse_addr(sockfd)) {
 820                 close(sockfd);
 821                 return 0;
 822         }
 823
 824         if ( bind(sockfd, (struct sockaddr *)&sin, sizeof sin) < 0 ) {
 825                 close(sockfd);
 826                 return 0;
 827         }
 828
 829         if (listen(sockfd, 5) < 0) {
 830                 close(sockfd);
 831                 return 0;
 832         }
 833
 834         flags = fcntl(sockfd, F_GETFD, 0);
 835         if (flags >= 0)
 836                 fcntl(sockfd, F_SETFD, flags | FD_CLOEXEC);
 837
 838         *socklist_p = xmalloc(sizeof(int));
 839         **socklist_p = sockfd;
 840         return 1;
 841 }
 842
 843 #endif
 844
 845 static int service_loop(int socknum, int *socklist)
 846 {
 847         struct pollfd *pfd;
 848         int i;
 849
 850         pfd = xcalloc(socknum, sizeof(struct pollfd));
 851
 852         for (i = 0; i < socknum; i++) {
 853                 pfd[i].fd = socklist[i];
 854                 pfd[i].events = POLLIN;
 855         }
 856
 857         signal(SIGCHLD, child_handler);
 858
 859         for (;;) {
 860                 int i;
 861
 862                 check_dead_children();
 863
 864                 if (poll(pfd, socknum, -1) < 0) {
 865                         if (errno != EINTR) {
 866                                 logerror("Poll failed, resuming: %s",
 867                                       strerror(errno));
 868                                 sleep(1);
 869                         }
 870                         continue;
 871                 }
 872
 873                 for (i = 0; i < socknum; i++) {
 874                         if (pfd[i].revents & POLLIN) {
 875                                 struct sockaddr_storage ss;
 876                                 unsigned int sslen = sizeof(ss);
 877                                 int incoming = accept(pfd[i].fd, (struct sockaddr *)&ss, &sslen);
 878                                 if (incoming < 0) {
 879                                         switch (errno) {
 880                                         case EAGAIN:
 881                                         case EINTR:
 882                                         case ECONNABORTED:
 883                                                 continue;
 884                                         default:
 885                                                 die("accept returned %s", strerror(errno));
 886                                         }
 887                                 }
 888                                 handle(incoming, (struct sockaddr *)&ss, sslen);
 889                         }
 890                 }
 891         }
 892 }
 893
 894 /* if any standard file descriptor is missing open it to /dev/null */
 895 static void sanitize_stdfds(void)
 896 {
 897         int fd = open("/dev/null", O_RDWR, 0);
 898         while (fd != -1 && fd < 2)
 899                 fd = dup(fd);
 900         if (fd == -1)
 901                 die("open /dev/null or dup failed: %s", strerror(errno));
 902         if (fd > 2)
 903                 close(fd);
 904 }
 905
 906 static void daemonize(void)
 907 {
 908         switch (fork()) {
 909                 case 0:
 910                         break;
 911                 case -1:
 912                         die("fork failed: %s", strerror(errno));
 913                 default:
 914                         exit(0);
 915         }
 916         if (setsid() == -1)
 917                 die("setsid failed: %s", strerror(errno));
 918         close(0);
 919         close(1);
 920         close(2);
 921         sanitize_stdfds();
 922 }
 923
 924 static void store_pid(const char *path)
 925 {
 926         FILE *f = fopen(path, "w");
 927         if (!f)
 928                 die("cannot open pid file %s: %s", path, strerror(errno));
 929         if (fprintf(f, "%"PRIuMAX"\n", (uintmax_t) getpid()) < 0 || fclose(f) != 0)
 930                 die("failed to write pid file %s: %s", path, strerror(errno));
 931 }
 932
 933 static int serve(char *listen_addr, int listen_port, struct passwd *pass, gid_t gid)
 934 {
 935         int socknum, *socklist;
 936
 937         socknum = socksetup(listen_addr, listen_port, &socklist);
 938         if (socknum == 0)
 939                 die("unable to allocate any listen sockets on host %s port %u",
 940                     listen_addr, listen_port);
 941
 942         if (pass && gid &&
 943             (initgroups(pass->pw_name, gid) || setgid (gid) ||
 944              setuid(pass->pw_uid)))
 945                 die("cannot drop privileges");
 946
 947         return service_loop(socknum, socklist);
 948 }
 949
 950 int main(int argc, char **argv)
 951 {
 952         int listen_port = 0;
 953         char *listen_addr = NULL;
 954         int inetd_mode = 0;
 955         const char *pid_file = NULL, *user_name = NULL, *group_name = NULL;
 956         int detach = 0;
 957         struct passwd *pass = NULL;
 958         struct group *group;
 959         gid_t gid = 0;
 960         int i;
 961
 962         for (i = 1; i < argc; i++) {
 963                 char *arg = argv[i];
 964
 965                 if (!prefixcmp(arg, "--listen=")) {
 966                     char *p = arg + 9;
 967                     char *ph = listen_addr = xmalloc(strlen(arg + 9) + 1);
 968                     while (*p)
 969                         *ph++ = tolower(*p++);
 970                     *ph = 0;
 971                     continue;
 972                 }
 973                 if (!prefixcmp(arg, "--port=")) {
 974                         char *end;
 975                         unsigned long n;
 976                         n = strtoul(arg+7, &end, 0);
 977                         if (arg[7] && !*end) {
 978                                 listen_port = n;
 979                                 continue;
 980                         }
 981                 }
 982                 if (!strcmp(arg, "--inetd")) {
 983                         inetd_mode = 1;
 984                         log_syslog = 1;
 985                         continue;
 986                 }
 987                 if (!strcmp(arg, "--verbose")) {
 988                         verbose = 1;
 989                         continue;
 990                 }
 991                 if (!strcmp(arg, "--syslog")) {
 992                         log_syslog = 1;
 993                         continue;
 994                 }
 995                 if (!strcmp(arg, "--export-all")) {
 996                         export_all_trees = 1;
 997                         continue;
 998                 }
 999                 if (!prefixcmp(arg, "--timeout=")) {
1000                         timeout = atoi(arg+10);
1001                         continue;
1002                 }
1003                 if (!prefixcmp(arg, "--init-timeout=")) {
1004                         init_timeout = atoi(arg+15);
1005                         continue;
1006                 }
1007                 if (!prefixcmp(arg, "--max-connections=")) {
1008                         max_connections = atoi(arg+18);
1009                         if (max_connections < 0)
1010                                 max_connections = 0;            /* unlimited */
1011                         continue;
1012                 }
1013                 if (!strcmp(arg, "--strict-paths")) {
1014                         strict_paths = 1;
1015                         continue;
1016                 }
1017                 if (!prefixcmp(arg, "--base-path=")) {
1018                         base_path = arg+12;
1019                         continue;
1020                 }
1021                 if (!strcmp(arg, "--base-path-relaxed")) {
1022                         base_path_relaxed = 1;
1023                         continue;
1024                 }
1025                 if (!prefixcmp(arg, "--interpolated-path=")) {
1026                         interpolated_path = arg+20;
1027                         continue;
1028                 }
1029                 if (!strcmp(arg, "--reuseaddr")) {
1030                         reuseaddr = 1;
1031                         continue;
1032                 }
1033                 if (!strcmp(arg, "--user-path")) {
1034                         user_path = "";
1035                         continue;
1036                 }
1037                 if (!prefixcmp(arg, "--user-path=")) {
1038                         user_path = arg + 12;
1039                         continue;
1040                 }
1041                 if (!prefixcmp(arg, "--pid-file=")) {
1042                         pid_file = arg + 11;
1043                         continue;
1044                 }
1045                 if (!strcmp(arg, "--detach")) {
1046                         detach = 1;
1047                         log_syslog = 1;
1048                         continue;
1049                 }
1050                 if (!prefixcmp(arg, "--user=")) {
1051                         user_name = arg + 7;
1052                         continue;
1053                 }
1054                 if (!prefixcmp(arg, "--group=")) {
1055                         group_name = arg + 8;
1056                         continue;
1057                 }
1058                 if (!prefixcmp(arg, "--enable=")) {
1059                         enable_service(arg + 9, 1);
1060                         continue;
1061                 }
1062                 if (!prefixcmp(arg, "--disable=")) {
1063                         enable_service(arg + 10, 0);
1064                         continue;
1065                 }
1066                 if (!prefixcmp(arg, "--allow-override=")) {
1067                         make_service_overridable(arg + 17, 1);
1068                         continue;
1069                 }
1070                 if (!prefixcmp(arg, "--forbid-override=")) {
1071                         make_service_overridable(arg + 18, 0);
1072                         continue;
1073                 }
1074                 if (!strcmp(arg, "--")) {
1075                         ok_paths = &argv[i+1];
1076                         break;
1077                 } else if (arg[0] != '-') {
1078                         ok_paths = &argv[i];
1079                         break;
1080                 }
1081
1082                 usage(daemon_usage);
1083         }
1084
1085         if (log_syslog) {
1086                 openlog("git-daemon", LOG_PID, LOG_DAEMON);
1087                 set_die_routine(daemon_die);
1088         } else
1089                 /* avoid splitting a message in the middle */
1090                 setvbuf(stderr, NULL, _IOLBF, 0);
1091
1092         if (inetd_mode && (group_name || user_name))
1093                 die("--user and --group are incompatible with --inetd");
1094
1095         if (inetd_mode && (listen_port || listen_addr))
1096                 die("--listen= and --port= are incompatible with --inetd");
1097         else if (listen_port == 0)
1098                 listen_port = DEFAULT_GIT_PORT;
1099
1100         if (group_name && !user_name)
1101                 die("--group supplied without --user");
1102
1103         if (user_name) {
1104                 pass = getpwnam(user_name);
1105                 if (!pass)
1106                         die("user not found - %s", user_name);
1107
1108                 if (!group_name)
1109                         gid = pass->pw_gid;
1110                 else {
1111                         group = getgrnam(group_name);
1112                         if (!group)
1113                                 die("group not found - %s", group_name);
1114
1115                         gid = group->gr_gid;
1116                 }
1117         }
1118
1119         if (strict_paths && (!ok_paths || !*ok_paths))
1120                 die("option --strict-paths requires a whitelist");
1121
1122         if (base_path && !is_directory(base_path))
1123                 die("base-path '%s' does not exist or is not a directory",
1124                     base_path);
1125
1126         if (inetd_mode) {
1127                 struct sockaddr_storage ss;
1128                 struct sockaddr *peer = (struct sockaddr *)&ss;
1129                 socklen_t slen = sizeof(ss);
1130
1131                 freopen("/dev/null", "w", stderr);
1132
1133                 if (getpeername(0, peer, &slen))
1134                         peer = NULL;
1135
1136                 return execute(peer);
1137         }
1138
1139         if (detach) {
1140                 daemonize();
1141                 loginfo("Ready to rumble");
1142         }
1143         else
1144                 sanitize_stdfds();
1145
1146         if (pid_file)
1147                 store_pid(pid_file);
1148
1149         return serve(listen_addr, listen_port, pass, gid);
1150 }