daemon.c

   1 #include "cache.h"
   2 #include "pkt-line.h"
   3 #include "exec_cmd.h"
   4 #include "interpolate.h"
   5
   6 #include <syslog.h>
   7
   8 #ifndef HOST_NAME_MAX
   9 #define HOST_NAME_MAX 256
  10 #endif
  11
  12 static int log_syslog;
  13 static int verbose;
  14 static int reuseaddr;
  15
  16 static const char daemon_usage[] =
  17 "git-daemon [--verbose] [--syslog] [--export-all]\n"
  18 "           [--timeout=n] [--init-timeout=n] [--strict-paths]\n"
  19 "           [--base-path=path] [--user-path | --user-path=path]\n"
  20 "           [--interpolated-path=path]\n"
  21 "           [--reuseaddr] [--detach] [--pid-file=file]\n"
  22 "           [--[enable|disable|allow-override|forbid-override]=service]\n"
  23 "           [--inetd | [--listen=host_or_ipaddr] [--port=n]\n"
  24 "                      [--user=user [--group=group]]\n"
  25 "           [directory...]";
  26
  27 /* List of acceptable pathname prefixes */
  28 static char **ok_paths;
  29 static int strict_paths;
  30
  31 /* If this is set, git-daemon-export-ok is not required */
  32 static int export_all_trees;
  33
  34 /* Take all paths relative to this one if non-NULL */
  35 static char *base_path;
  36 static char *interpolated_path;
  37
  38 /* Flag indicating client sent extra args. */
  39 static int saw_extended_args;
  40
  41 /* If defined, ~user notation is allowed and the string is inserted
  42  * after ~user/.  E.g. a request to git://host/~alice/frotz would
  43  * go to /home/alice/pub_git/frotz with --user-path=pub_git.
  44  */
  45 static const char *user_path;
  46
  47 /* Timeout, and initial timeout */
  48 static unsigned int timeout;
  49 static unsigned int init_timeout;
  50
  51 /*
  52  * Static table for now.  Ugh.
  53  * Feel free to make dynamic as needed.
  54  */
  55 #define INTERP_SLOT_HOST        (0)
  56 #define INTERP_SLOT_CANON_HOST  (1)
  57 #define INTERP_SLOT_IP          (2)
  58 #define INTERP_SLOT_PORT        (3)
  59 #define INTERP_SLOT_DIR         (4)
  60 #define INTERP_SLOT_PERCENT     (5)
  61
  62 static struct interp interp_table[] = {
  63         { "%H", 0},
  64         { "%CH", 0},
  65         { "%IP", 0},
  66         { "%P", 0},
  67         { "%D", 0},
  68         { "%%", 0},
  69 };
  70
  71
  72 static void logreport(int priority, const char *err, va_list params)
  73 {
  74         /* We should do a single write so that it is atomic and output
  75          * of several processes do not get intermingled. */
  76         char buf[1024];
  77         int buflen;
  78         int maxlen, msglen;
  79
  80         /* sizeof(buf) should be big enough for "[pid] \n" */
  81         buflen = snprintf(buf, sizeof(buf), "[%ld] ", (long) getpid());
  82
  83         maxlen = sizeof(buf) - buflen - 1; /* -1 for our own LF */
  84         msglen = vsnprintf(buf + buflen, maxlen, err, params);
  85
  86         if (log_syslog) {
  87                 syslog(priority, "%s", buf);
  88                 return;
  89         }
  90
  91         /* maxlen counted our own LF but also counts space given to
  92          * vsnprintf for the terminating NUL.  We want to make sure that
  93          * we have space for our own LF and NUL after the "meat" of the
  94          * message, so truncate it at maxlen - 1.
  95          */
  96         if (msglen > maxlen - 1)
  97                 msglen = maxlen - 1;
  98         else if (msglen < 0)
  99                 msglen = 0; /* Protect against weird return values. */
 100         buflen += msglen;
 101
 102         buf[buflen++] = '\n';
 103         buf[buflen] = '\0';
 104
 105         write(2, buf, buflen);
 106 }
 107
 108 static void logerror(const char *err, ...)
 109 {
 110         va_list params;
 111         va_start(params, err);
 112         logreport(LOG_ERR, err, params);
 113         va_end(params);
 114 }
 115
 116 static void loginfo(const char *err, ...)
 117 {
 118         va_list params;
 119         if (!verbose)
 120                 return;
 121         va_start(params, err);
 122         logreport(LOG_INFO, err, params);
 123         va_end(params);
 124 }
 125
 126 static void NORETURN daemon_die(const char *err, va_list params)
 127 {
 128         logreport(LOG_ERR, err, params);
 129         exit(1);
 130 }
 131
 132 static int avoid_alias(char *p)
 133 {
 134         int sl, ndot;
 135
 136         /*
 137          * This resurrects the belts and suspenders paranoia check by HPA
 138          * done in <435560F7.4080006@zytor.com> thread, now enter_repo()
 139          * does not do getcwd() based path canonicalizations.
 140          *
 141          * sl becomes true immediately after seeing '/' and continues to
 142          * be true as long as dots continue after that without intervening
 143          * non-dot character.
 144          */
 145         if (!p || (*p != '/' && *p != '~'))
 146                 return -1;
 147         sl = 1; ndot = 0;
 148         p++;
 149
 150         while (1) {
 151                 char ch = *p++;
 152                 if (sl) {
 153                         if (ch == '.')
 154                                 ndot++;
 155                         else if (ch == '/') {
 156                                 if (ndot < 3)
 157                                         /* reject //, /./ and /../ */
 158                                         return -1;
 159                                 ndot = 0;
 160                         }
 161                         else if (ch == 0) {
 162                                 if (0 < ndot && ndot < 3)
 163                                         /* reject /.$ and /..$ */
 164                                         return -1;
 165                                 return 0;
 166                         }
 167                         else
 168                                 sl = ndot = 0;
 169                 }
 170                 else if (ch == 0)
 171                         return 0;
 172                 else if (ch == '/') {
 173                         sl = 1;
 174                         ndot = 0;
 175                 }
 176         }
 177 }
 178
 179 static char *path_ok(struct interp *itable)
 180 {
 181         static char rpath[PATH_MAX];
 182         static char interp_path[PATH_MAX];
 183         char *path;
 184         char *dir;
 185
 186         dir = itable[INTERP_SLOT_DIR].value;
 187
 188         if (avoid_alias(dir)) {
 189                 logerror("'%s': aliased", dir);
 190                 return NULL;
 191         }
 192
 193         if (*dir == '~') {
 194                 if (!user_path) {
 195                         logerror("'%s': User-path not allowed", dir);
 196                         return NULL;
 197                 }
 198                 if (*user_path) {
 199                         /* Got either "~alice" or "~alice/foo";
 200                          * rewrite them to "~alice/%s" or
 201                          * "~alice/%s/foo".
 202                          */
 203                         int namlen, restlen = strlen(dir);
 204                         char *slash = strchr(dir, '/');
 205                         if (!slash)
 206                                 slash = dir + restlen;
 207                         namlen = slash - dir;
 208                         restlen -= namlen;
 209                         loginfo("userpath <%s>, request <%s>, namlen %d, restlen %d, slash <%s>", user_path, dir, namlen, restlen, slash);
 210                         snprintf(rpath, PATH_MAX, "%.*s/%s%.*s",
 211                                  namlen, dir, user_path, restlen, slash);
 212                         dir = rpath;
 213                 }
 214         }
 215         else if (interpolated_path && saw_extended_args) {
 216                 if (*dir != '/') {
 217                         /* Allow only absolute */
 218                         logerror("'%s': Non-absolute path denied (interpolated-path active)", dir);
 219                         return NULL;
 220                 }
 221
 222                 interpolate(interp_path, PATH_MAX, interpolated_path,
 223                             interp_table, ARRAY_SIZE(interp_table));
 224                 loginfo("Interpolated dir '%s'", interp_path);
 225
 226                 dir = interp_path;
 227         }
 228         else if (base_path) {
 229                 if (*dir != '/') {
 230                         /* Allow only absolute */
 231                         logerror("'%s': Non-absolute path denied (base-path active)", dir);
 232                         return NULL;
 233                 }
 234                 snprintf(rpath, PATH_MAX, "%s%s", base_path, dir);
 235                 dir = rpath;
 236         }
 237
 238         path = enter_repo(dir, strict_paths);
 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)
 288 {
 289         if (!strncmp(var, "daemon.", 7) &&
 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 interp *itable, struct daemon_service *service)
 300 {
 301         const char *path;
 302         int enabled = service->enabled;
 303
 304         loginfo("Request %s for '%s'",
 305                 service->name,
 306                 itable[INTERP_SLOT_DIR].value);
 307
 308         if (!enabled && !service->overridable) {
 309                 logerror("'%s': service not enabled.", service->name);
 310                 errno = EACCES;
 311                 return -1;
 312         }
 313
 314         if (!(path = path_ok(itable)))
 315                 return -1;
 316
 317         /*
 318          * Security on the cheap.
 319          *
 320          * We want a readable HEAD, usable "objects" directory, and
 321          * a "git-daemon-export-ok" flag that says that the other side
 322          * is ok with us doing this.
 323          *
 324          * path_ok() uses enter_repo() and does whitelist checking.
 325          * We only need to make sure the repository is exported.
 326          */
 327
 328         if (!export_all_trees && access("git-daemon-export-ok", F_OK)) {
 329                 logerror("'%s': repository not exported.", path);
 330                 errno = EACCES;
 331                 return -1;
 332         }
 333
 334         if (service->overridable) {
 335                 service_looking_at = service;
 336                 service_enabled = -1;
 337                 git_config(git_daemon_config);
 338                 if (0 <= service_enabled)
 339                         enabled = service_enabled;
 340         }
 341         if (!enabled) {
 342                 logerror("'%s': service not enabled for '%s'",
 343                          service->name, path);
 344                 errno = EACCES;
 345                 return -1;
 346         }
 347
 348         /*
 349          * We'll ignore SIGTERM from now on, we have a
 350          * good client.
 351          */
 352         signal(SIGTERM, SIG_IGN);
 353
 354         return service->fn();
 355 }
 356
 357 static int upload_pack(void)
 358 {
 359         /* Timeout as string */
 360         char timeout_buf[64];
 361
 362         snprintf(timeout_buf, sizeof timeout_buf, "--timeout=%u", timeout);
 363
 364         /* git-upload-pack only ever reads stuff, so this is safe */
 365         execl_git_cmd("upload-pack", "--strict", timeout_buf, ".", NULL);
 366         return -1;
 367 }
 368
 369 static int upload_archive(void)
 370 {
 371         execl_git_cmd("upload-archive", ".", NULL);
 372         return -1;
 373 }
 374
 375 static struct daemon_service daemon_service[] = {
 376         { "upload-archive", "uploadarch", upload_archive, 0, 1 },
 377         { "upload-pack", "uploadpack", upload_pack, 1, 1 },
 378 };
 379
 380 static void enable_service(const char *name, int ena) {
 381         int i;
 382         for (i = 0; i < ARRAY_SIZE(daemon_service); i++) {
 383                 if (!strcmp(daemon_service[i].name, name)) {
 384                         daemon_service[i].enabled = ena;
 385                         return;
 386                 }
 387         }
 388         die("No such service %s", name);
 389 }
 390
 391 static void make_service_overridable(const char *name, int ena) {
 392         int i;
 393         for (i = 0; i < ARRAY_SIZE(daemon_service); i++) {
 394                 if (!strcmp(daemon_service[i].name, name)) {
 395                         daemon_service[i].overridable = ena;
 396                         return;
 397                 }
 398         }
 399         die("No such service %s", name);
 400 }
 401
 402 /*
 403  * Separate the "extra args" information as supplied by the client connection.
 404  * Any resulting data is squirrelled away in the given interpolation table.
 405  */
 406 static void parse_extra_args(struct interp *table, char *extra_args, int buflen)
 407 {
 408         char *val;
 409         int vallen;
 410         char *end = extra_args + buflen;
 411
 412         while (extra_args < end && *extra_args) {
 413                 saw_extended_args = 1;
 414                 if (strncasecmp("host=", extra_args, 5) == 0) {
 415                         val = extra_args + 5;
 416                         vallen = strlen(val) + 1;
 417                         if (*val) {
 418                                 /* Split <host>:<port> at colon. */
 419                                 char *host = val;
 420                                 char *port = strrchr(host, ':');
 421                                 if (port) {
 422                                         *port = 0;
 423                                         port++;
 424                                         interp_set_entry(table, INTERP_SLOT_PORT, port);
 425                                 }
 426                                 interp_set_entry(table, INTERP_SLOT_HOST, host);
 427                         }
 428
 429                         /* On to the next one */
 430                         extra_args = val + vallen;
 431                 }
 432         }
 433 }
 434
 435 void fill_in_extra_table_entries(struct interp *itable)
 436 {
 437         char *hp;
 438
 439         /*
 440          * Replace literal host with lowercase-ized hostname.
 441          */
 442         hp = interp_table[INTERP_SLOT_HOST].value;
 443         if (!hp)
 444                 return;
 445         for ( ; *hp; hp++)
 446                 *hp = tolower(*hp);
 447
 448         /*
 449          * Locate canonical hostname and its IP address.
 450          */
 451 #ifndef NO_IPV6
 452         {
 453                 struct addrinfo hints;
 454                 struct addrinfo *ai, *ai0;
 455                 int gai;
 456                 static char addrbuf[HOST_NAME_MAX + 1];
 457
 458                 memset(&hints, 0, sizeof(hints));
 459                 hints.ai_flags = AI_CANONNAME;
 460
 461                 gai = getaddrinfo(interp_table[INTERP_SLOT_HOST].value, 0, &hints, &ai0);
 462                 if (!gai) {
 463                         for (ai = ai0; ai; ai = ai->ai_next) {
 464                                 struct sockaddr_in *sin_addr = (void *)ai->ai_addr;
 465
 466                                 inet_ntop(AF_INET, &sin_addr->sin_addr,
 467                                           addrbuf, sizeof(addrbuf));
 468                                 interp_set_entry(interp_table,
 469                                                  INTERP_SLOT_CANON_HOST, ai->ai_canonname);
 470                                 interp_set_entry(interp_table,
 471                                                  INTERP_SLOT_IP, addrbuf);
 472                                 break;
 473                         }
 474                         freeaddrinfo(ai0);
 475                 }
 476         }
 477 #else
 478         {
 479                 struct hostent *hent;
 480                 struct sockaddr_in sa;
 481                 char **ap;
 482                 static char addrbuf[HOST_NAME_MAX + 1];
 483
 484                 hent = gethostbyname(interp_table[INTERP_SLOT_HOST].value);
 485
 486                 ap = hent->h_addr_list;
 487                 memset(&sa, 0, sizeof sa);
 488                 sa.sin_family = hent->h_addrtype;
 489                 sa.sin_port = htons(0);
 490                 memcpy(&sa.sin_addr, *ap, hent->h_length);
 491
 492                 inet_ntop(hent->h_addrtype, &sa.sin_addr,
 493                           addrbuf, sizeof(addrbuf));
 494
 495                 interp_set_entry(interp_table, INTERP_SLOT_CANON_HOST, hent->h_name);
 496                 interp_set_entry(interp_table, INTERP_SLOT_IP, addrbuf);
 497         }
 498 #endif
 499 }
 500
 501
 502 static int execute(struct sockaddr *addr)
 503 {
 504         static char line[1000];
 505         int pktlen, len, i;
 506
 507         if (addr) {
 508                 char addrbuf[256] = "";
 509                 int port = -1;
 510
 511                 if (addr->sa_family == AF_INET) {
 512                         struct sockaddr_in *sin_addr = (void *) addr;
 513                         inet_ntop(addr->sa_family, &sin_addr->sin_addr, addrbuf, sizeof(addrbuf));
 514                         port = sin_addr->sin_port;
 515 #ifndef NO_IPV6
 516                 } else if (addr && addr->sa_family == AF_INET6) {
 517                         struct sockaddr_in6 *sin6_addr = (void *) addr;
 518
 519                         char *buf = addrbuf;
 520                         *buf++ = '['; *buf = '\0'; /* stpcpy() is cool */
 521                         inet_ntop(AF_INET6, &sin6_addr->sin6_addr, buf, sizeof(addrbuf) - 1);
 522                         strcat(buf, "]");
 523
 524                         port = sin6_addr->sin6_port;
 525 #endif
 526                 }
 527                 loginfo("Connection from %s:%d", addrbuf, port);
 528         }
 529
 530         alarm(init_timeout ? init_timeout : timeout);
 531         pktlen = packet_read_line(0, line, sizeof(line));
 532         alarm(0);
 533
 534         len = strlen(line);
 535         if (pktlen != len)
 536                 loginfo("Extended attributes (%d bytes) exist <%.*s>",
 537                         (int) pktlen - len,
 538                         (int) pktlen - len, line + len + 1);
 539         if (len && line[len-1] == '\n') {
 540                 line[--len] = 0;
 541                 pktlen--;
 542         }
 543
 544         /*
 545          * Initialize the path interpolation table for this connection.
 546          */
 547         interp_clear_table(interp_table, ARRAY_SIZE(interp_table));
 548         interp_set_entry(interp_table, INTERP_SLOT_PERCENT, "%");
 549
 550         if (len != pktlen) {
 551             parse_extra_args(interp_table, line + len + 1, pktlen - len - 1);
 552             fill_in_extra_table_entries(interp_table);
 553         }
 554
 555         for (i = 0; i < ARRAY_SIZE(daemon_service); i++) {
 556                 struct daemon_service *s = &(daemon_service[i]);
 557                 int namelen = strlen(s->name);
 558                 if (!strncmp("git-", line, 4) &&
 559                     !strncmp(s->name, line + 4, namelen) &&
 560                     line[namelen + 4] == ' ') {
 561                         /*
 562                          * Note: The directory here is probably context sensitive,
 563                          * and might depend on the actual service being performed.
 564                          */
 565                         interp_set_entry(interp_table,
 566                                          INTERP_SLOT_DIR, line + namelen + 5);
 567                         return run_service(interp_table, s);
 568                 }
 569         }
 570
 571         logerror("Protocol error: '%s'", line);
 572         return -1;
 573 }
 574
 575
 576 /*
 577  * We count spawned/reaped separately, just to avoid any
 578  * races when updating them from signals. The SIGCHLD handler
 579  * will only update children_reaped, and the fork logic will
 580  * only update children_spawned.
 581  *
 582  * MAX_CHILDREN should be a power-of-two to make the modulus
 583  * operation cheap. It should also be at least twice
 584  * the maximum number of connections we will ever allow.
 585  */
 586 #define MAX_CHILDREN 128
 587
 588 static int max_connections = 25;
 589
 590 /* These are updated by the signal handler */
 591 static volatile unsigned int children_reaped;
 592 static pid_t dead_child[MAX_CHILDREN];
 593
 594 /* These are updated by the main loop */
 595 static unsigned int children_spawned;
 596 static unsigned int children_deleted;
 597
 598 static struct child {
 599         pid_t pid;
 600         int addrlen;
 601         struct sockaddr_storage address;
 602 } live_child[MAX_CHILDREN];
 603
 604 static void add_child(int idx, pid_t pid, struct sockaddr *addr, int addrlen)
 605 {
 606         live_child[idx].pid = pid;
 607         live_child[idx].addrlen = addrlen;
 608         memcpy(&live_child[idx].address, addr, addrlen);
 609 }
 610
 611 /*
 612  * Walk from "deleted" to "spawned", and remove child "pid".
 613  *
 614  * We move everything up by one, since the new "deleted" will
 615  * be one higher.
 616  */
 617 static void remove_child(pid_t pid, unsigned deleted, unsigned spawned)
 618 {
 619         struct child n;
 620
 621         deleted %= MAX_CHILDREN;
 622         spawned %= MAX_CHILDREN;
 623         if (live_child[deleted].pid == pid) {
 624                 live_child[deleted].pid = -1;
 625                 return;
 626         }
 627         n = live_child[deleted];
 628         for (;;) {
 629                 struct child m;
 630                 deleted = (deleted + 1) % MAX_CHILDREN;
 631                 if (deleted == spawned)
 632                         die("could not find dead child %d\n", pid);
 633                 m = live_child[deleted];
 634                 live_child[deleted] = n;
 635                 if (m.pid == pid)
 636                         return;
 637                 n = m;
 638         }
 639 }
 640
 641 /*
 642  * This gets called if the number of connections grows
 643  * past "max_connections".
 644  *
 645  * We _should_ start off by searching for connections
 646  * from the same IP, and if there is some address wth
 647  * multiple connections, we should kill that first.
 648  *
 649  * As it is, we just "randomly" kill 25% of the connections,
 650  * and our pseudo-random generator sucks too. I have no
 651  * shame.
 652  *
 653  * Really, this is just a place-holder for a _real_ algorithm.
 654  */
 655 static void kill_some_children(int signo, unsigned start, unsigned stop)
 656 {
 657         start %= MAX_CHILDREN;
 658         stop %= MAX_CHILDREN;
 659         while (start != stop) {
 660                 if (!(start & 3))
 661                         kill(live_child[start].pid, signo);
 662                 start = (start + 1) % MAX_CHILDREN;
 663         }
 664 }
 665
 666 static void check_max_connections(void)
 667 {
 668         for (;;) {
 669                 int active;
 670                 unsigned spawned, reaped, deleted;
 671
 672                 spawned = children_spawned;
 673                 reaped = children_reaped;
 674                 deleted = children_deleted;
 675
 676                 while (deleted < reaped) {
 677                         pid_t pid = dead_child[deleted % MAX_CHILDREN];
 678                         remove_child(pid, deleted, spawned);
 679                         deleted++;
 680                 }
 681                 children_deleted = deleted;
 682
 683                 active = spawned - deleted;
 684                 if (active <= max_connections)
 685                         break;
 686
 687                 /* Kill some unstarted connections with SIGTERM */
 688                 kill_some_children(SIGTERM, deleted, spawned);
 689                 if (active <= max_connections << 1)
 690                         break;
 691
 692                 /* If the SIGTERM thing isn't helping use SIGKILL */
 693                 kill_some_children(SIGKILL, deleted, spawned);
 694                 sleep(1);
 695         }
 696 }
 697
 698 static void handle(int incoming, struct sockaddr *addr, int addrlen)
 699 {
 700         pid_t pid = fork();
 701
 702         if (pid) {
 703                 unsigned idx;
 704
 705                 close(incoming);
 706                 if (pid < 0)
 707                         return;
 708
 709                 idx = children_spawned % MAX_CHILDREN;
 710                 children_spawned++;
 711                 add_child(idx, pid, addr, addrlen);
 712
 713                 check_max_connections();
 714                 return;
 715         }
 716
 717         dup2(incoming, 0);
 718         dup2(incoming, 1);
 719         close(incoming);
 720
 721         exit(execute(addr));
 722 }
 723
 724 static void child_handler(int signo)
 725 {
 726         for (;;) {
 727                 int status;
 728                 pid_t pid = waitpid(-1, &status, WNOHANG);
 729
 730                 if (pid > 0) {
 731                         unsigned reaped = children_reaped;
 732                         dead_child[reaped % MAX_CHILDREN] = pid;
 733                         children_reaped = reaped + 1;
 734                         /* XXX: Custom logging, since we don't wanna getpid() */
 735                         if (verbose) {
 736                                 const char *dead = "";
 737                                 if (!WIFEXITED(status) || WEXITSTATUS(status) > 0)
 738                                         dead = " (with error)";
 739                                 if (log_syslog)
 740                                         syslog(LOG_INFO, "[%d] Disconnected%s", pid, dead);
 741                                 else
 742                                         fprintf(stderr, "[%d] Disconnected%s\n", pid, dead);
 743                         }
 744                         continue;
 745                 }
 746                 break;
 747         }
 748 }
 749
 750 static int set_reuse_addr(int sockfd)
 751 {
 752         int on = 1;
 753
 754         if (!reuseaddr)
 755                 return 0;
 756         return setsockopt(sockfd, SOL_SOCKET, SO_REUSEADDR,
 757                           &on, sizeof(on));
 758 }
 759
 760 #ifndef NO_IPV6
 761
 762 static int socksetup(char *listen_addr, int listen_port, int **socklist_p)
 763 {
 764         int socknum = 0, *socklist = NULL;
 765         int maxfd = -1;
 766         char pbuf[NI_MAXSERV];
 767         struct addrinfo hints, *ai0, *ai;
 768         int gai;
 769
 770         sprintf(pbuf, "%d", listen_port);
 771         memset(&hints, 0, sizeof(hints));
 772         hints.ai_family = AF_UNSPEC;
 773         hints.ai_socktype = SOCK_STREAM;
 774         hints.ai_protocol = IPPROTO_TCP;
 775         hints.ai_flags = AI_PASSIVE;
 776
 777         gai = getaddrinfo(listen_addr, pbuf, &hints, &ai0);
 778         if (gai)
 779                 die("getaddrinfo() failed: %s\n", gai_strerror(gai));
 780
 781         for (ai = ai0; ai; ai = ai->ai_next) {
 782                 int sockfd;
 783
 784                 sockfd = socket(ai->ai_family, ai->ai_socktype, ai->ai_protocol);
 785                 if (sockfd < 0)
 786                         continue;
 787                 if (sockfd >= FD_SETSIZE) {
 788                         error("too large socket descriptor.");
 789                         close(sockfd);
 790                         continue;
 791                 }
 792
 793 #ifdef IPV6_V6ONLY
 794                 if (ai->ai_family == AF_INET6) {
 795                         int on = 1;
 796                         setsockopt(sockfd, IPPROTO_IPV6, IPV6_V6ONLY,
 797                                    &on, sizeof(on));
 798                         /* Note: error is not fatal */
 799                 }
 800 #endif
 801
 802                 if (set_reuse_addr(sockfd)) {
 803                         close(sockfd);
 804                         continue;
 805                 }
 806
 807                 if (bind(sockfd, ai->ai_addr, ai->ai_addrlen) < 0) {
 808                         close(sockfd);
 809                         continue;       /* not fatal */
 810                 }
 811                 if (listen(sockfd, 5) < 0) {
 812                         close(sockfd);
 813                         continue;       /* not fatal */
 814                 }
 815
 816                 socklist = xrealloc(socklist, sizeof(int) * (socknum + 1));
 817                 socklist[socknum++] = sockfd;
 818
 819                 if (maxfd < sockfd)
 820                         maxfd = sockfd;
 821         }
 822
 823         freeaddrinfo(ai0);
 824
 825         *socklist_p = socklist;
 826         return socknum;
 827 }
 828
 829 #else /* NO_IPV6 */
 830
 831 static int socksetup(char *listen_addr, int listen_port, int **socklist_p)
 832 {
 833         struct sockaddr_in sin;
 834         int sockfd;
 835
 836         memset(&sin, 0, sizeof sin);
 837         sin.sin_family = AF_INET;
 838         sin.sin_port = htons(listen_port);
 839
 840         if (listen_addr) {
 841                 /* Well, host better be an IP address here. */
 842                 if (inet_pton(AF_INET, listen_addr, &sin.sin_addr.s_addr) <= 0)
 843                         return 0;
 844         } else {
 845                 sin.sin_addr.s_addr = htonl(INADDR_ANY);
 846         }
 847
 848         sockfd = socket(AF_INET, SOCK_STREAM, 0);
 849         if (sockfd < 0)
 850                 return 0;
 851
 852         if (set_reuse_addr(sockfd)) {
 853                 close(sockfd);
 854                 return 0;
 855         }
 856
 857         if ( bind(sockfd, (struct sockaddr *)&sin, sizeof sin) < 0 ) {
 858                 close(sockfd);
 859                 return 0;
 860         }
 861
 862         if (listen(sockfd, 5) < 0) {
 863                 close(sockfd);
 864                 return 0;
 865         }
 866
 867         *socklist_p = xmalloc(sizeof(int));
 868         **socklist_p = sockfd;
 869         return 1;
 870 }
 871
 872 #endif
 873
 874 static int service_loop(int socknum, int *socklist)
 875 {
 876         struct pollfd *pfd;
 877         int i;
 878
 879         pfd = xcalloc(socknum, sizeof(struct pollfd));
 880
 881         for (i = 0; i < socknum; i++) {
 882                 pfd[i].fd = socklist[i];
 883                 pfd[i].events = POLLIN;
 884         }
 885
 886         signal(SIGCHLD, child_handler);
 887
 888         for (;;) {
 889                 int i;
 890
 891                 if (poll(pfd, socknum, -1) < 0) {
 892                         if (errno != EINTR) {
 893                                 error("poll failed, resuming: %s",
 894                                       strerror(errno));
 895                                 sleep(1);
 896                         }
 897                         continue;
 898                 }
 899
 900                 for (i = 0; i < socknum; i++) {
 901                         if (pfd[i].revents & POLLIN) {
 902                                 struct sockaddr_storage ss;
 903                                 unsigned int sslen = sizeof(ss);
 904                                 int incoming = accept(pfd[i].fd, (struct sockaddr *)&ss, &sslen);
 905                                 if (incoming < 0) {
 906                                         switch (errno) {
 907                                         case EAGAIN:
 908                                         case EINTR:
 909                                         case ECONNABORTED:
 910                                                 continue;
 911                                         default:
 912                                                 die("accept returned %s", strerror(errno));
 913                                         }
 914                                 }
 915                                 handle(incoming, (struct sockaddr *)&ss, sslen);
 916                         }
 917                 }
 918         }
 919 }
 920
 921 /* if any standard file descriptor is missing open it to /dev/null */
 922 static void sanitize_stdfds(void)
 923 {
 924         int fd = open("/dev/null", O_RDWR, 0);
 925         while (fd != -1 && fd < 2)
 926                 fd = dup(fd);
 927         if (fd == -1)
 928                 die("open /dev/null or dup failed: %s", strerror(errno));
 929         if (fd > 2)
 930                 close(fd);
 931 }
 932
 933 static void daemonize(void)
 934 {
 935         switch (fork()) {
 936                 case 0:
 937                         break;
 938                 case -1:
 939                         die("fork failed: %s", strerror(errno));
 940                 default:
 941                         exit(0);
 942         }
 943         if (setsid() == -1)
 944                 die("setsid failed: %s", strerror(errno));
 945         close(0);
 946         close(1);
 947         close(2);
 948         sanitize_stdfds();
 949 }
 950
 951 static void store_pid(const char *path)
 952 {
 953         FILE *f = fopen(path, "w");
 954         if (!f)
 955                 die("cannot open pid file %s: %s", path, strerror(errno));
 956         fprintf(f, "%d\n", getpid());
 957         fclose(f);
 958 }
 959
 960 static int serve(char *listen_addr, int listen_port, struct passwd *pass, gid_t gid)
 961 {
 962         int socknum, *socklist;
 963
 964         socknum = socksetup(listen_addr, listen_port, &socklist);
 965         if (socknum == 0)
 966                 die("unable to allocate any listen sockets on host %s port %u",
 967                     listen_addr, listen_port);
 968
 969         if (pass && gid &&
 970             (initgroups(pass->pw_name, gid) || setgid (gid) ||
 971              setuid(pass->pw_uid)))
 972                 die("cannot drop privileges");
 973
 974         return service_loop(socknum, socklist);
 975 }
 976
 977 int main(int argc, char **argv)
 978 {
 979         int listen_port = 0;
 980         char *listen_addr = NULL;
 981         int inetd_mode = 0;
 982         const char *pid_file = NULL, *user_name = NULL, *group_name = NULL;
 983         int detach = 0;
 984         struct passwd *pass = NULL;
 985         struct group *group;
 986         gid_t gid = 0;
 987         int i;
 988
 989         /* Without this we cannot rely on waitpid() to tell
 990          * what happened to our children.
 991          */
 992         signal(SIGCHLD, SIG_DFL);
 993
 994         for (i = 1; i < argc; i++) {
 995                 char *arg = argv[i];
 996
 997                 if (!strncmp(arg, "--listen=", 9)) {
 998                     char *p = arg + 9;
 999                     char *ph = listen_addr = xmalloc(strlen(arg + 9) + 1);
1000                     while (*p)
1001                         *ph++ = tolower(*p++);
1002                     *ph = 0;
1003                     continue;
1004                 }
1005                 if (!strncmp(arg, "--port=", 7)) {
1006                         char *end;
1007                         unsigned long n;
1008                         n = strtoul(arg+7, &end, 0);
1009                         if (arg[7] && !*end) {
1010                                 listen_port = n;
1011                                 continue;
1012                         }
1013                 }
1014                 if (!strcmp(arg, "--inetd")) {
1015                         inetd_mode = 1;
1016                         log_syslog = 1;
1017                         continue;
1018                 }
1019                 if (!strcmp(arg, "--verbose")) {
1020                         verbose = 1;
1021                         continue;
1022                 }
1023                 if (!strcmp(arg, "--syslog")) {
1024                         log_syslog = 1;
1025                         continue;
1026                 }
1027                 if (!strcmp(arg, "--export-all")) {
1028                         export_all_trees = 1;
1029                         continue;
1030                 }
1031                 if (!strncmp(arg, "--timeout=", 10)) {
1032                         timeout = atoi(arg+10);
1033                         continue;
1034                 }
1035                 if (!strncmp(arg, "--init-timeout=", 15)) {
1036                         init_timeout = atoi(arg+15);
1037                         continue;
1038                 }
1039                 if (!strcmp(arg, "--strict-paths")) {
1040                         strict_paths = 1;
1041                         continue;
1042                 }
1043                 if (!strncmp(arg, "--base-path=", 12)) {
1044                         base_path = arg+12;
1045                         continue;
1046                 }
1047                 if (!strncmp(arg, "--interpolated-path=", 20)) {
1048                         interpolated_path = arg+20;
1049                         continue;
1050                 }
1051                 if (!strcmp(arg, "--reuseaddr")) {
1052                         reuseaddr = 1;
1053                         continue;
1054                 }
1055                 if (!strcmp(arg, "--user-path")) {
1056                         user_path = "";
1057                         continue;
1058                 }
1059                 if (!strncmp(arg, "--user-path=", 12)) {
1060                         user_path = arg + 12;
1061                         continue;
1062                 }
1063                 if (!strncmp(arg, "--pid-file=", 11)) {
1064                         pid_file = arg + 11;
1065                         continue;
1066                 }
1067                 if (!strcmp(arg, "--detach")) {
1068                         detach = 1;
1069                         log_syslog = 1;
1070                         continue;
1071                 }
1072                 if (!strncmp(arg, "--user=", 7)) {
1073                         user_name = arg + 7;
1074                         continue;
1075                 }
1076                 if (!strncmp(arg, "--group=", 8)) {
1077                         group_name = arg + 8;
1078                         continue;
1079                 }
1080                 if (!strncmp(arg, "--enable=", 9)) {
1081                         enable_service(arg + 9, 1);
1082                         continue;
1083                 }
1084                 if (!strncmp(arg, "--disable=", 10)) {
1085                         enable_service(arg + 10, 0);
1086                         continue;
1087                 }
1088                 if (!strncmp(arg, "--allow-override=", 17)) {
1089                         make_service_overridable(arg + 17, 1);
1090                         continue;
1091                 }
1092                 if (!strncmp(arg, "--forbid-override=", 18)) {
1093                         make_service_overridable(arg + 18, 0);
1094                         continue;
1095                 }
1096                 if (!strcmp(arg, "--")) {
1097                         ok_paths = &argv[i+1];
1098                         break;
1099                 } else if (arg[0] != '-') {
1100                         ok_paths = &argv[i];
1101                         break;
1102                 }
1103
1104                 usage(daemon_usage);
1105         }
1106
1107         if (inetd_mode && (group_name || user_name))
1108                 die("--user and --group are incompatible with --inetd");
1109
1110         if (inetd_mode && (listen_port || listen_addr))
1111                 die("--listen= and --port= are incompatible with --inetd");
1112         else if (listen_port == 0)
1113                 listen_port = DEFAULT_GIT_PORT;
1114
1115         if (group_name && !user_name)
1116                 die("--group supplied without --user");
1117
1118         if (user_name) {
1119                 pass = getpwnam(user_name);
1120                 if (!pass)
1121                         die("user not found - %s", user_name);
1122
1123                 if (!group_name)
1124                         gid = pass->pw_gid;
1125                 else {
1126                         group = getgrnam(group_name);
1127                         if (!group)
1128                                 die("group not found - %s", group_name);
1129
1130                         gid = group->gr_gid;
1131                 }
1132         }
1133
1134         if (log_syslog) {
1135                 openlog("git-daemon", 0, LOG_DAEMON);
1136                 set_die_routine(daemon_die);
1137         }
1138
1139         if (strict_paths && (!ok_paths || !*ok_paths))
1140                 die("option --strict-paths requires a whitelist");
1141
1142         if (inetd_mode) {
1143                 struct sockaddr_storage ss;
1144                 struct sockaddr *peer = (struct sockaddr *)&ss;
1145                 socklen_t slen = sizeof(ss);
1146
1147                 freopen("/dev/null", "w", stderr);
1148
1149                 if (getpeername(0, peer, &slen))
1150                         peer = NULL;
1151
1152                 return execute(peer);
1153         }
1154
1155         if (detach)
1156                 daemonize();
1157         else
1158                 sanitize_stdfds();
1159
1160         if (pid_file)
1161                 store_pid(pid_file);
1162
1163         return serve(listen_addr, listen_port, pass, gid);
1164 }