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

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