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

   1 #include "git-compat-util.h"
   2 #include "cache.h"
   3 #include "config.h"
   4 #include "pkt-line.h"
   5 #include "quote.h"
   6 #include "refs.h"
   7 #include "run-command.h"
   8 #include "remote.h"
   9 #include "connect.h"
  10 #include "url.h"
  11 #include "string-list.h"
  12 #include "sha1-array.h"
  13 #include "transport.h"
  14 #include "strbuf.h"
  15 #include "version.h"
  16 #include "protocol.h"
  17 #include "alias.h"
  18
  19 static char *server_capabilities_v1;
  20 static struct argv_array server_capabilities_v2 = ARGV_ARRAY_INIT;
  21 static const char *parse_feature_value(const char *, const char *, int *);
  22
  23 static int check_ref(const char *name, unsigned int flags)
  24 {
  25         if (!flags)
  26                 return 1;
  27
  28         if (!skip_prefix(name, "refs/", &name))
  29                 return 0;
  30
  31         /* REF_NORMAL means that we don't want the magic fake tag refs */
  32         if ((flags & REF_NORMAL) && check_refname_format(name, 0))
  33                 return 0;
  34
  35         /* REF_HEADS means that we want regular branch heads */
  36         if ((flags & REF_HEADS) && starts_with(name, "heads/"))
  37                 return 1;
  38
  39         /* REF_TAGS means that we want tags */
  40         if ((flags & REF_TAGS) && starts_with(name, "tags/"))
  41                 return 1;
  42
  43         /* All type bits clear means that we are ok with anything */
  44         return !(flags & ~REF_NORMAL);
  45 }
  46
  47 int check_ref_type(const struct ref *ref, int flags)
  48 {
  49         return check_ref(ref->name, flags);
  50 }
  51
  52 static NORETURN void die_initial_contact(int unexpected)
  53 {
  54         /*
  55          * A hang-up after seeing some response from the other end
  56          * means that it is unexpected, as we know the other end is
  57          * willing to talk to us.  A hang-up before seeing any
  58          * response does not necessarily mean an ACL problem, though.
  59          */
  60         if (unexpected)
  61                 die(_("The remote end hung up upon initial contact"));
  62         else
  63                 die(_("Could not read from remote repository.\n\n"
  64                       "Please make sure you have the correct access rights\n"
  65                       "and the repository exists."));
  66 }
  67
  68 /* Checks if the server supports the capability 'c' */
  69 int server_supports_v2(const char *c, int die_on_error)
  70 {
  71         int i;
  72
  73         for (i = 0; i < server_capabilities_v2.argc; i++) {
  74                 const char *out;
  75                 if (skip_prefix(server_capabilities_v2.argv[i], c, &out) &&
  76                     (!*out || *out == '='))
  77                         return 1;
  78         }
  79
  80         if (die_on_error)
  81                 die("server doesn't support '%s'", c);
  82
  83         return 0;
  84 }
  85
  86 int server_supports_feature(const char *c, const char *feature,
  87                             int die_on_error)
  88 {
  89         int i;
  90
  91         for (i = 0; i < server_capabilities_v2.argc; i++) {
  92                 const char *out;
  93                 if (skip_prefix(server_capabilities_v2.argv[i], c, &out) &&
  94                     (!*out || *(out++) == '=')) {
  95                         if (parse_feature_request(out, feature))
  96                                 return 1;
  97                         else
  98                                 break;
  99                 }
 100         }
 101
 102         if (die_on_error)
 103                 die("server doesn't support feature '%s'", feature);
 104
 105         return 0;
 106 }
 107
 108 static void process_capabilities_v2(struct packet_reader *reader)
 109 {
 110         while (packet_reader_read(reader) == PACKET_READ_NORMAL)
 111                 argv_array_push(&server_capabilities_v2, reader->line);
 112
 113         if (reader->status != PACKET_READ_FLUSH)
 114                 die("expected flush after capabilities");
 115 }
 116
 117 enum protocol_version discover_version(struct packet_reader *reader)
 118 {
 119         enum protocol_version version = protocol_unknown_version;
 120
 121         /*
 122          * Peek the first line of the server's response to
 123          * determine the protocol version the server is speaking.
 124          */
 125         switch (packet_reader_peek(reader)) {
 126         case PACKET_READ_EOF:
 127                 die_initial_contact(0);
 128         case PACKET_READ_FLUSH:
 129         case PACKET_READ_DELIM:
 130                 version = protocol_v0;
 131                 break;
 132         case PACKET_READ_NORMAL:
 133                 version = determine_protocol_version_client(reader->line);
 134                 break;
 135         }
 136
 137         switch (version) {
 138         case protocol_v2:
 139                 process_capabilities_v2(reader);
 140                 break;
 141         case protocol_v1:
 142                 /* Read the peeked version line */
 143                 packet_reader_read(reader);
 144                 break;
 145         case protocol_v0:
 146                 break;
 147         case protocol_unknown_version:
 148                 BUG("unknown protocol version");
 149         }
 150
 151         return version;
 152 }
 153
 154 static void parse_one_symref_info(struct string_list *symref, const char *val, int len)
 155 {
 156         char *sym, *target;
 157         struct string_list_item *item;
 158
 159         if (!len)
 160                 return; /* just "symref" */
 161         /* e.g. "symref=HEAD:refs/heads/master" */
 162         sym = xmemdupz(val, len);
 163         target = strchr(sym, ':');
 164         if (!target)
 165                 /* just "symref=something" */
 166                 goto reject;
 167         *(target++) = '\0';
 168         if (check_refname_format(sym, REFNAME_ALLOW_ONELEVEL) ||
 169             check_refname_format(target, REFNAME_ALLOW_ONELEVEL))
 170                 /* "symref=bogus:pair */
 171                 goto reject;
 172         item = string_list_append_nodup(symref, sym);
 173         item->util = target;
 174         return;
 175 reject:
 176         free(sym);
 177         return;
 178 }
 179
 180 static void annotate_refs_with_symref_info(struct ref *ref)
 181 {
 182         struct string_list symref = STRING_LIST_INIT_DUP;
 183         const char *feature_list = server_capabilities_v1;
 184
 185         while (feature_list) {
 186                 int len;
 187                 const char *val;
 188
 189                 val = parse_feature_value(feature_list, "symref", &len);
 190                 if (!val)
 191                         break;
 192                 parse_one_symref_info(&symref, val, len);
 193                 feature_list = val + 1;
 194         }
 195         string_list_sort(&symref);
 196
 197         for (; ref; ref = ref->next) {
 198                 struct string_list_item *item;
 199                 item = string_list_lookup(&symref, ref->name);
 200                 if (!item)
 201                         continue;
 202                 ref->symref = xstrdup((char *)item->util);
 203         }
 204         string_list_clear(&symref, 0);
 205 }
 206
 207 static void process_capabilities(const char *line, int *len)
 208 {
 209         int nul_location = strlen(line);
 210         if (nul_location == *len)
 211                 return;
 212         server_capabilities_v1 = xstrdup(line + nul_location + 1);
 213         *len = nul_location;
 214 }
 215
 216 static int process_dummy_ref(const char *line)
 217 {
 218         struct object_id oid;
 219         const char *name;
 220
 221         if (parse_oid_hex(line, &oid, &name))
 222                 return 0;
 223         if (*name != ' ')
 224                 return 0;
 225         name++;
 226
 227         return !oidcmp(&null_oid, &oid) && !strcmp(name, "capabilities^{}");
 228 }
 229
 230 static void check_no_capabilities(const char *line, int len)
 231 {
 232         if (strlen(line) != len)
 233                 warning("Ignoring capabilities after first line '%s'",
 234                         line + strlen(line));
 235 }
 236
 237 static int process_ref(const char *line, int len, struct ref ***list,
 238                        unsigned int flags, struct oid_array *extra_have)
 239 {
 240         struct object_id old_oid;
 241         const char *name;
 242
 243         if (parse_oid_hex(line, &old_oid, &name))
 244                 return 0;
 245         if (*name != ' ')
 246                 return 0;
 247         name++;
 248
 249         if (extra_have && !strcmp(name, ".have")) {
 250                 oid_array_append(extra_have, &old_oid);
 251         } else if (!strcmp(name, "capabilities^{}")) {
 252                 die("protocol error: unexpected capabilities^{}");
 253         } else if (check_ref(name, flags)) {
 254                 struct ref *ref = alloc_ref(name);
 255                 oidcpy(&ref->old_oid, &old_oid);
 256                 **list = ref;
 257                 *list = &ref->next;
 258         }
 259         check_no_capabilities(line, len);
 260         return 1;
 261 }
 262
 263 static int process_shallow(const char *line, int len,
 264                            struct oid_array *shallow_points)
 265 {
 266         const char *arg;
 267         struct object_id old_oid;
 268
 269         if (!skip_prefix(line, "shallow ", &arg))
 270                 return 0;
 271
 272         if (get_oid_hex(arg, &old_oid))
 273                 die("protocol error: expected shallow sha-1, got '%s'", arg);
 274         if (!shallow_points)
 275                 die("repository on the other end cannot be shallow");
 276         oid_array_append(shallow_points, &old_oid);
 277         check_no_capabilities(line, len);
 278         return 1;
 279 }
 280
 281 enum get_remote_heads_state {
 282         EXPECTING_FIRST_REF = 0,
 283         EXPECTING_REF,
 284         EXPECTING_SHALLOW,
 285         EXPECTING_DONE,
 286 };
 287
 288 /*
 289  * Read all the refs from the other end
 290  */
 291 struct ref **get_remote_heads(struct packet_reader *reader,
 292                               struct ref **list, unsigned int flags,
 293                               struct oid_array *extra_have,
 294                               struct oid_array *shallow_points)
 295 {
 296         struct ref **orig_list = list;
 297         int len = 0;
 298         enum get_remote_heads_state state = EXPECTING_FIRST_REF;
 299         const char *arg;
 300
 301         *list = NULL;
 302
 303         while (state != EXPECTING_DONE) {
 304                 switch (packet_reader_read(reader)) {
 305                 case PACKET_READ_EOF:
 306                         die_initial_contact(1);
 307                 case PACKET_READ_NORMAL:
 308                         len = reader->pktlen;
 309                         if (len > 4 && skip_prefix(reader->line, "ERR ", &arg))
 310                                 die("remote error: %s", arg);
 311                         break;
 312                 case PACKET_READ_FLUSH:
 313                         state = EXPECTING_DONE;
 314                         break;
 315                 case PACKET_READ_DELIM:
 316                         die("invalid packet");
 317                 }
 318
 319                 switch (state) {
 320                 case EXPECTING_FIRST_REF:
 321                         process_capabilities(reader->line, &len);
 322                         if (process_dummy_ref(reader->line)) {
 323                                 state = EXPECTING_SHALLOW;
 324                                 break;
 325                         }
 326                         state = EXPECTING_REF;
 327                         /* fallthrough */
 328                 case EXPECTING_REF:
 329                         if (process_ref(reader->line, len, &list, flags, extra_have))
 330                                 break;
 331                         state = EXPECTING_SHALLOW;
 332                         /* fallthrough */
 333                 case EXPECTING_SHALLOW:
 334                         if (process_shallow(reader->line, len, shallow_points))
 335                                 break;
 336                         die("protocol error: unexpected '%s'", reader->line);
 337                 case EXPECTING_DONE:
 338                         break;
 339                 }
 340         }
 341
 342         annotate_refs_with_symref_info(*orig_list);
 343
 344         return list;
 345 }
 346
 347 /* Returns 1 when a valid ref has been added to `list`, 0 otherwise */
 348 static int process_ref_v2(const char *line, struct ref ***list)
 349 {
 350         int ret = 1;
 351         int i = 0;
 352         struct object_id old_oid;
 353         struct ref *ref;
 354         struct string_list line_sections = STRING_LIST_INIT_DUP;
 355         const char *end;
 356
 357         /*
 358          * Ref lines have a number of fields which are space deliminated.  The
 359          * first field is the OID of the ref.  The second field is the ref
 360          * name.  Subsequent fields (symref-target and peeled) are optional and
 361          * don't have a particular order.
 362          */
 363         if (string_list_split(&line_sections, line, ' ', -1) < 2) {
 364                 ret = 0;
 365                 goto out;
 366         }
 367
 368         if (parse_oid_hex(line_sections.items[i++].string, &old_oid, &end) ||
 369             *end) {
 370                 ret = 0;
 371                 goto out;
 372         }
 373
 374         ref = alloc_ref(line_sections.items[i++].string);
 375
 376         oidcpy(&ref->old_oid, &old_oid);
 377         **list = ref;
 378         *list = &ref->next;
 379
 380         for (; i < line_sections.nr; i++) {
 381                 const char *arg = line_sections.items[i].string;
 382                 if (skip_prefix(arg, "symref-target:", &arg))
 383                         ref->symref = xstrdup(arg);
 384
 385                 if (skip_prefix(arg, "peeled:", &arg)) {
 386                         struct object_id peeled_oid;
 387                         char *peeled_name;
 388                         struct ref *peeled;
 389                         if (parse_oid_hex(arg, &peeled_oid, &end) || *end) {
 390                                 ret = 0;
 391                                 goto out;
 392                         }
 393
 394                         peeled_name = xstrfmt("%s^{}", ref->name);
 395                         peeled = alloc_ref(peeled_name);
 396
 397                         oidcpy(&peeled->old_oid, &peeled_oid);
 398                         **list = peeled;
 399                         *list = &peeled->next;
 400
 401                         free(peeled_name);
 402                 }
 403         }
 404
 405 out:
 406         string_list_clear(&line_sections, 0);
 407         return ret;
 408 }
 409
 410 struct ref **get_remote_refs(int fd_out, struct packet_reader *reader,
 411                              struct ref **list, int for_push,
 412                              const struct argv_array *ref_prefixes,
 413                              const struct string_list *server_options)
 414 {
 415         int i;
 416         *list = NULL;
 417
 418         if (server_supports_v2("ls-refs", 1))
 419                 packet_write_fmt(fd_out, "command=ls-refs\n");
 420
 421         if (server_supports_v2("agent", 0))
 422                 packet_write_fmt(fd_out, "agent=%s", git_user_agent_sanitized());
 423
 424         if (server_options && server_options->nr &&
 425             server_supports_v2("server-option", 1))
 426                 for (i = 0; i < server_options->nr; i++)
 427                         packet_write_fmt(fd_out, "server-option=%s",
 428                                          server_options->items[i].string);
 429
 430         packet_delim(fd_out);
 431         /* When pushing we don't want to request the peeled tags */
 432         if (!for_push)
 433                 packet_write_fmt(fd_out, "peel\n");
 434         packet_write_fmt(fd_out, "symrefs\n");
 435         for (i = 0; ref_prefixes && i < ref_prefixes->argc; i++) {
 436                 packet_write_fmt(fd_out, "ref-prefix %s\n",
 437                                  ref_prefixes->argv[i]);
 438         }
 439         packet_flush(fd_out);
 440
 441         /* Process response from server */
 442         while (packet_reader_read(reader) == PACKET_READ_NORMAL) {
 443                 if (!process_ref_v2(reader->line, &list))
 444                         die("invalid ls-refs response: %s", reader->line);
 445         }
 446
 447         if (reader->status != PACKET_READ_FLUSH)
 448                 die("expected flush after ref listing");
 449
 450         return list;
 451 }
 452
 453 static const char *parse_feature_value(const char *feature_list, const char *feature, int *lenp)
 454 {
 455         int len;
 456
 457         if (!feature_list)
 458                 return NULL;
 459
 460         len = strlen(feature);
 461         while (*feature_list) {
 462                 const char *found = strstr(feature_list, feature);
 463                 if (!found)
 464                         return NULL;
 465                 if (feature_list == found || isspace(found[-1])) {
 466                         const char *value = found + len;
 467                         /* feature with no value (e.g., "thin-pack") */
 468                         if (!*value || isspace(*value)) {
 469                                 if (lenp)
 470                                         *lenp = 0;
 471                                 return value;
 472                         }
 473                         /* feature with a value (e.g., "agent=git/1.2.3") */
 474                         else if (*value == '=') {
 475                                 value++;
 476                                 if (lenp)
 477                                         *lenp = strcspn(value, " \t\n");
 478                                 return value;
 479                         }
 480                         /*
 481                          * otherwise we matched a substring of another feature;
 482                          * keep looking
 483                          */
 484                 }
 485                 feature_list = found + 1;
 486         }
 487         return NULL;
 488 }
 489
 490 int parse_feature_request(const char *feature_list, const char *feature)
 491 {
 492         return !!parse_feature_value(feature_list, feature, NULL);
 493 }
 494
 495 const char *server_feature_value(const char *feature, int *len)
 496 {
 497         return parse_feature_value(server_capabilities_v1, feature, len);
 498 }
 499
 500 int server_supports(const char *feature)
 501 {
 502         return !!server_feature_value(feature, NULL);
 503 }
 504
 505 enum protocol {
 506         PROTO_LOCAL = 1,
 507         PROTO_FILE,
 508         PROTO_SSH,
 509         PROTO_GIT
 510 };
 511
 512 int url_is_local_not_ssh(const char *url)
 513 {
 514         const char *colon = strchr(url, ':');
 515         const char *slash = strchr(url, '/');
 516         return !colon || (slash && slash < colon) ||
 517                 (has_dos_drive_prefix(url) && is_valid_path(url));
 518 }
 519
 520 static const char *prot_name(enum protocol protocol)
 521 {
 522         switch (protocol) {
 523                 case PROTO_LOCAL:
 524                 case PROTO_FILE:
 525                         return "file";
 526                 case PROTO_SSH:
 527                         return "ssh";
 528                 case PROTO_GIT:
 529                         return "git";
 530                 default:
 531                         return "unknown protocol";
 532         }
 533 }
 534
 535 static enum protocol get_protocol(const char *name)
 536 {
 537         if (!strcmp(name, "ssh"))
 538                 return PROTO_SSH;
 539         if (!strcmp(name, "git"))
 540                 return PROTO_GIT;
 541         if (!strcmp(name, "git+ssh")) /* deprecated - do not use */
 542                 return PROTO_SSH;
 543         if (!strcmp(name, "ssh+git")) /* deprecated - do not use */
 544                 return PROTO_SSH;
 545         if (!strcmp(name, "file"))
 546                 return PROTO_FILE;
 547         die("I don't handle protocol '%s'", name);
 548 }
 549
 550 static char *host_end(char **hoststart, int removebrackets)
 551 {
 552         char *host = *hoststart;
 553         char *end;
 554         char *start = strstr(host, "@[");
 555         if (start)
 556                 start++; /* Jump over '@' */
 557         else
 558                 start = host;
 559         if (start[0] == '[') {
 560                 end = strchr(start + 1, ']');
 561                 if (end) {
 562                         if (removebrackets) {
 563                                 *end = 0;
 564                                 memmove(start, start + 1, end - start);
 565                                 end++;
 566                         }
 567                 } else
 568                         end = host;
 569         } else
 570                 end = host;
 571         return end;
 572 }
 573
 574 #define STR_(s) # s
 575 #define STR(s)  STR_(s)
 576
 577 static void get_host_and_port(char **host, const char **port)
 578 {
 579         char *colon, *end;
 580         end = host_end(host, 1);
 581         colon = strchr(end, ':');
 582         if (colon) {
 583                 long portnr = strtol(colon + 1, &end, 10);
 584                 if (end != colon + 1 && *end == '\0' && 0 <= portnr && portnr < 65536) {
 585                         *colon = 0;
 586                         *port = colon + 1;
 587                 } else if (!colon[1]) {
 588                         *colon = 0;
 589                 }
 590         }
 591 }
 592
 593 static void enable_keepalive(int sockfd)
 594 {
 595         int ka = 1;
 596
 597         if (setsockopt(sockfd, SOL_SOCKET, SO_KEEPALIVE, &ka, sizeof(ka)) < 0)
 598                 fprintf(stderr, "unable to set SO_KEEPALIVE on socket: %s\n",
 599                         strerror(errno));
 600 }
 601
 602 #ifndef NO_IPV6
 603
 604 static const char *ai_name(const struct addrinfo *ai)
 605 {
 606         static char addr[NI_MAXHOST];
 607         if (getnameinfo(ai->ai_addr, ai->ai_addrlen, addr, sizeof(addr), NULL, 0,
 608                         NI_NUMERICHOST) != 0)
 609                 xsnprintf(addr, sizeof(addr), "(unknown)");
 610
 611         return addr;
 612 }
 613
 614 /*
 615  * Returns a connected socket() fd, or else die()s.
 616  */
 617 static int git_tcp_connect_sock(char *host, int flags)
 618 {
 619         struct strbuf error_message = STRBUF_INIT;
 620         int sockfd = -1;
 621         const char *port = STR(DEFAULT_GIT_PORT);
 622         struct addrinfo hints, *ai0, *ai;
 623         int gai;
 624         int cnt = 0;
 625
 626         get_host_and_port(&host, &port);
 627         if (!*port)
 628                 port = "<none>";
 629
 630         memset(&hints, 0, sizeof(hints));
 631         if (flags & CONNECT_IPV4)
 632                 hints.ai_family = AF_INET;
 633         else if (flags & CONNECT_IPV6)
 634                 hints.ai_family = AF_INET6;
 635         hints.ai_socktype = SOCK_STREAM;
 636         hints.ai_protocol = IPPROTO_TCP;
 637
 638         if (flags & CONNECT_VERBOSE)
 639                 fprintf(stderr, "Looking up %s ... ", host);
 640
 641         gai = getaddrinfo(host, port, &hints, &ai);
 642         if (gai)
 643                 die("Unable to look up %s (port %s) (%s)", host, port, gai_strerror(gai));
 644
 645         if (flags & CONNECT_VERBOSE)
 646                 fprintf(stderr, "done.\nConnecting to %s (port %s) ... ", host, port);
 647
 648         for (ai0 = ai; ai; ai = ai->ai_next, cnt++) {
 649                 sockfd = socket(ai->ai_family,
 650                                 ai->ai_socktype, ai->ai_protocol);
 651                 if ((sockfd < 0) ||
 652                     (connect(sockfd, ai->ai_addr, ai->ai_addrlen) < 0)) {
 653                         strbuf_addf(&error_message, "%s[%d: %s]: errno=%s\n",
 654                                     host, cnt, ai_name(ai), strerror(errno));
 655                         if (0 <= sockfd)
 656                                 close(sockfd);
 657                         sockfd = -1;
 658                         continue;
 659                 }
 660                 if (flags & CONNECT_VERBOSE)
 661                         fprintf(stderr, "%s ", ai_name(ai));
 662                 break;
 663         }
 664
 665         freeaddrinfo(ai0);
 666
 667         if (sockfd < 0)
 668                 die("unable to connect to %s:\n%s", host, error_message.buf);
 669
 670         enable_keepalive(sockfd);
 671
 672         if (flags & CONNECT_VERBOSE)
 673                 fprintf(stderr, "done.\n");
 674
 675         strbuf_release(&error_message);
 676
 677         return sockfd;
 678 }
 679
 680 #else /* NO_IPV6 */
 681
 682 /*
 683  * Returns a connected socket() fd, or else die()s.
 684  */
 685 static int git_tcp_connect_sock(char *host, int flags)
 686 {
 687         struct strbuf error_message = STRBUF_INIT;
 688         int sockfd = -1;
 689         const char *port = STR(DEFAULT_GIT_PORT);
 690         char *ep;
 691         struct hostent *he;
 692         struct sockaddr_in sa;
 693         char **ap;
 694         unsigned int nport;
 695         int cnt;
 696
 697         get_host_and_port(&host, &port);
 698
 699         if (flags & CONNECT_VERBOSE)
 700                 fprintf(stderr, "Looking up %s ... ", host);
 701
 702         he = gethostbyname(host);
 703         if (!he)
 704                 die("Unable to look up %s (%s)", host, hstrerror(h_errno));
 705         nport = strtoul(port, &ep, 10);
 706         if ( ep == port || *ep ) {
 707                 /* Not numeric */
 708                 struct servent *se = getservbyname(port,"tcp");
 709                 if ( !se )
 710                         die("Unknown port %s", port);
 711                 nport = se->s_port;
 712         }
 713
 714         if (flags & CONNECT_VERBOSE)
 715                 fprintf(stderr, "done.\nConnecting to %s (port %s) ... ", host, port);
 716
 717         for (cnt = 0, ap = he->h_addr_list; *ap; ap++, cnt++) {
 718                 memset(&sa, 0, sizeof sa);
 719                 sa.sin_family = he->h_addrtype;
 720                 sa.sin_port = htons(nport);
 721                 memcpy(&sa.sin_addr, *ap, he->h_length);
 722
 723                 sockfd = socket(he->h_addrtype, SOCK_STREAM, 0);
 724                 if ((sockfd < 0) ||
 725                     connect(sockfd, (struct sockaddr *)&sa, sizeof sa) < 0) {
 726                         strbuf_addf(&error_message, "%s[%d: %s]: errno=%s\n",
 727                                 host,
 728                                 cnt,
 729                                 inet_ntoa(*(struct in_addr *)&sa.sin_addr),
 730                                 strerror(errno));
 731                         if (0 <= sockfd)
 732                                 close(sockfd);
 733                         sockfd = -1;
 734                         continue;
 735                 }
 736                 if (flags & CONNECT_VERBOSE)
 737                         fprintf(stderr, "%s ",
 738                                 inet_ntoa(*(struct in_addr *)&sa.sin_addr));
 739                 break;
 740         }
 741
 742         if (sockfd < 0)
 743                 die("unable to connect to %s:\n%s", host, error_message.buf);
 744
 745         enable_keepalive(sockfd);
 746
 747         if (flags & CONNECT_VERBOSE)
 748                 fprintf(stderr, "done.\n");
 749
 750         return sockfd;
 751 }
 752
 753 #endif /* NO_IPV6 */
 754
 755
 756 /*
 757  * Dummy child_process returned by git_connect() if the transport protocol
 758  * does not need fork(2).
 759  */
 760 static struct child_process no_fork = CHILD_PROCESS_INIT;
 761
 762 int git_connection_is_socket(struct child_process *conn)
 763 {
 764         return conn == &no_fork;
 765 }
 766
 767 static struct child_process *git_tcp_connect(int fd[2], char *host, int flags)
 768 {
 769         int sockfd = git_tcp_connect_sock(host, flags);
 770
 771         fd[0] = sockfd;
 772         fd[1] = dup(sockfd);
 773
 774         return &no_fork;
 775 }
 776
 777
 778 static char *git_proxy_command;
 779
 780 static int git_proxy_command_options(const char *var, const char *value,
 781                 void *cb)
 782 {
 783         if (!strcmp(var, "core.gitproxy")) {
 784                 const char *for_pos;
 785                 int matchlen = -1;
 786                 int hostlen;
 787                 const char *rhost_name = cb;
 788                 int rhost_len = strlen(rhost_name);
 789
 790                 if (git_proxy_command)
 791                         return 0;
 792                 if (!value)
 793                         return config_error_nonbool(var);
 794                 /* [core]
 795                  * ;# matches www.kernel.org as well
 796                  * gitproxy = netcatter-1 for kernel.org
 797                  * gitproxy = netcatter-2 for sample.xz
 798                  * gitproxy = netcatter-default
 799                  */
 800                 for_pos = strstr(value, " for ");
 801                 if (!for_pos)
 802                         /* matches everybody */
 803                         matchlen = strlen(value);
 804                 else {
 805                         hostlen = strlen(for_pos + 5);
 806                         if (rhost_len < hostlen)
 807                                 matchlen = -1;
 808                         else if (!strncmp(for_pos + 5,
 809                                           rhost_name + rhost_len - hostlen,
 810                                           hostlen) &&
 811                                  ((rhost_len == hostlen) ||
 812                                   rhost_name[rhost_len - hostlen -1] == '.'))
 813                                 matchlen = for_pos - value;
 814                         else
 815                                 matchlen = -1;
 816                 }
 817                 if (0 <= matchlen) {
 818                         /* core.gitproxy = none for kernel.org */
 819                         if (matchlen == 4 &&
 820                             !memcmp(value, "none", 4))
 821                                 matchlen = 0;
 822                         git_proxy_command = xmemdupz(value, matchlen);
 823                 }
 824                 return 0;
 825         }
 826
 827         return git_default_config(var, value, cb);
 828 }
 829
 830 static int git_use_proxy(const char *host)
 831 {
 832         git_proxy_command = getenv("GIT_PROXY_COMMAND");
 833         git_config(git_proxy_command_options, (void*)host);
 834         return (git_proxy_command && *git_proxy_command);
 835 }
 836
 837 static struct child_process *git_proxy_connect(int fd[2], char *host)
 838 {
 839         const char *port = STR(DEFAULT_GIT_PORT);
 840         struct child_process *proxy;
 841
 842         get_host_and_port(&host, &port);
 843
 844         if (looks_like_command_line_option(host))
 845                 die("strange hostname '%s' blocked", host);
 846         if (looks_like_command_line_option(port))
 847                 die("strange port '%s' blocked", port);
 848
 849         proxy = xmalloc(sizeof(*proxy));
 850         child_process_init(proxy);
 851         argv_array_push(&proxy->args, git_proxy_command);
 852         argv_array_push(&proxy->args, host);
 853         argv_array_push(&proxy->args, port);
 854         proxy->in = -1;
 855         proxy->out = -1;
 856         if (start_command(proxy))
 857                 die("cannot start proxy %s", git_proxy_command);
 858         fd[0] = proxy->out; /* read from proxy stdout */
 859         fd[1] = proxy->in;  /* write to proxy stdin */
 860         return proxy;
 861 }
 862
 863 static char *get_port(char *host)
 864 {
 865         char *end;
 866         char *p = strchr(host, ':');
 867
 868         if (p) {
 869                 long port = strtol(p + 1, &end, 10);
 870                 if (end != p + 1 && *end == '\0' && 0 <= port && port < 65536) {
 871                         *p = '\0';
 872                         return p+1;
 873                 }
 874         }
 875
 876         return NULL;
 877 }
 878
 879 /*
 880  * Extract protocol and relevant parts from the specified connection URL.
 881  * The caller must free() the returned strings.
 882  */
 883 static enum protocol parse_connect_url(const char *url_orig, char **ret_host,
 884                                        char **ret_path)
 885 {
 886         char *url;
 887         char *host, *path;
 888         char *end;
 889         int separator = '/';
 890         enum protocol protocol = PROTO_LOCAL;
 891
 892         if (is_url(url_orig))
 893                 url = url_decode(url_orig);
 894         else
 895                 url = xstrdup(url_orig);
 896
 897         host = strstr(url, "://");
 898         if (host) {
 899                 *host = '\0';
 900                 protocol = get_protocol(url);
 901                 host += 3;
 902         } else {
 903                 host = url;
 904                 if (!url_is_local_not_ssh(url)) {
 905                         protocol = PROTO_SSH;
 906                         separator = ':';
 907                 }
 908         }
 909
 910         /*
 911          * Don't do destructive transforms as protocol code does
 912          * '[]' unwrapping in get_host_and_port()
 913          */
 914         end = host_end(&host, 0);
 915
 916         if (protocol == PROTO_LOCAL)
 917                 path = end;
 918         else if (protocol == PROTO_FILE && has_dos_drive_prefix(end))
 919                 path = end; /* "file://$(pwd)" may be "file://C:/projects/repo" */
 920         else
 921                 path = strchr(end, separator);
 922
 923         if (!path || !*path)
 924                 die("No path specified. See 'man git-pull' for valid url syntax");
 925
 926         /*
 927          * null-terminate hostname and point path to ~ for URL's like this:
 928          *    ssh://host.xz/~user/repo
 929          */
 930
 931         end = path; /* Need to \0 terminate host here */
 932         if (separator == ':')
 933                 path++; /* path starts after ':' */
 934         if (protocol == PROTO_GIT || protocol == PROTO_SSH) {
 935                 if (path[1] == '~')
 936                         path++;
 937         }
 938
 939         path = xstrdup(path);
 940         *end = '\0';
 941
 942         *ret_host = xstrdup(host);
 943         *ret_path = path;
 944         free(url);
 945         return protocol;
 946 }
 947
 948 static const char *get_ssh_command(void)
 949 {
 950         const char *ssh;
 951
 952         if ((ssh = getenv("GIT_SSH_COMMAND")))
 953                 return ssh;
 954
 955         if (!git_config_get_string_const("core.sshcommand", &ssh))
 956                 return ssh;
 957
 958         return NULL;
 959 }
 960
 961 enum ssh_variant {
 962         VARIANT_AUTO,
 963         VARIANT_SIMPLE,
 964         VARIANT_SSH,
 965         VARIANT_PLINK,
 966         VARIANT_PUTTY,
 967         VARIANT_TORTOISEPLINK,
 968 };
 969
 970 static void override_ssh_variant(enum ssh_variant *ssh_variant)
 971 {
 972         const char *variant = getenv("GIT_SSH_VARIANT");
 973
 974         if (!variant && git_config_get_string_const("ssh.variant", &variant))
 975                 return;
 976
 977         if (!strcmp(variant, "auto"))
 978                 *ssh_variant = VARIANT_AUTO;
 979         else if (!strcmp(variant, "plink"))
 980                 *ssh_variant = VARIANT_PLINK;
 981         else if (!strcmp(variant, "putty"))
 982                 *ssh_variant = VARIANT_PUTTY;
 983         else if (!strcmp(variant, "tortoiseplink"))
 984                 *ssh_variant = VARIANT_TORTOISEPLINK;
 985         else if (!strcmp(variant, "simple"))
 986                 *ssh_variant = VARIANT_SIMPLE;
 987         else
 988                 *ssh_variant = VARIANT_SSH;
 989 }
 990
 991 static enum ssh_variant determine_ssh_variant(const char *ssh_command,
 992                                               int is_cmdline)
 993 {
 994         enum ssh_variant ssh_variant = VARIANT_AUTO;
 995         const char *variant;
 996         char *p = NULL;
 997
 998         override_ssh_variant(&ssh_variant);
 999
1000         if (ssh_variant != VARIANT_AUTO)
1001                 return ssh_variant;
1002
1003         if (!is_cmdline) {
1004                 p = xstrdup(ssh_command);
1005                 variant = basename(p);
1006         } else {
1007                 const char **ssh_argv;
1008
1009                 p = xstrdup(ssh_command);
1010                 if (split_cmdline(p, &ssh_argv) > 0) {
1011                         variant = basename((char *)ssh_argv[0]);
1012                         /*
1013                          * At this point, variant points into the buffer
1014                          * referenced by p, hence we do not need ssh_argv
1015                          * any longer.
1016                          */
1017                         free(ssh_argv);
1018                 } else {
1019                         free(p);
1020                         return ssh_variant;
1021                 }
1022         }
1023
1024         if (!strcasecmp(variant, "ssh") ||
1025             !strcasecmp(variant, "ssh.exe"))
1026                 ssh_variant = VARIANT_SSH;
1027         else if (!strcasecmp(variant, "plink") ||
1028                  !strcasecmp(variant, "plink.exe"))
1029                 ssh_variant = VARIANT_PLINK;
1030         else if (!strcasecmp(variant, "tortoiseplink") ||
1031                  !strcasecmp(variant, "tortoiseplink.exe"))
1032                 ssh_variant = VARIANT_TORTOISEPLINK;
1033
1034         free(p);
1035         return ssh_variant;
1036 }
1037
1038 /*
1039  * Open a connection using Git's native protocol.
1040  *
1041  * The caller is responsible for freeing hostandport, but this function may
1042  * modify it (for example, to truncate it to remove the port part).
1043  */
1044 static struct child_process *git_connect_git(int fd[2], char *hostandport,
1045                                              const char *path, const char *prog,
1046                                              enum protocol_version version,
1047                                              int flags)
1048 {
1049         struct child_process *conn;
1050         struct strbuf request = STRBUF_INIT;
1051         /*
1052          * Set up virtual host information based on where we will
1053          * connect, unless the user has overridden us in
1054          * the environment.
1055          */
1056         char *target_host = getenv("GIT_OVERRIDE_VIRTUAL_HOST");
1057         if (target_host)
1058                 target_host = xstrdup(target_host);
1059         else
1060                 target_host = xstrdup(hostandport);
1061
1062         transport_check_allowed("git");
1063
1064         /*
1065          * These underlying connection commands die() if they
1066          * cannot connect.
1067          */
1068         if (git_use_proxy(hostandport))
1069                 conn = git_proxy_connect(fd, hostandport);
1070         else
1071                 conn = git_tcp_connect(fd, hostandport, flags);
1072         /*
1073          * Separate original protocol components prog and path
1074          * from extended host header with a NUL byte.
1075          *
1076          * Note: Do not add any other headers here!  Doing so
1077          * will cause older git-daemon servers to crash.
1078          */
1079         strbuf_addf(&request,
1080                     "%s %s%chost=%s%c",
1081                     prog, path, 0,
1082                     target_host, 0);
1083
1084         /* If using a new version put that stuff here after a second null byte */
1085         if (version > 0) {
1086                 strbuf_addch(&request, '\0');
1087                 strbuf_addf(&request, "version=%d%c",
1088                             version, '\0');
1089         }
1090
1091         packet_write(fd[1], request.buf, request.len);
1092
1093         free(target_host);
1094         strbuf_release(&request);
1095         return conn;
1096 }
1097
1098 /*
1099  * Append the appropriate environment variables to `env` and options to
1100  * `args` for running ssh in Git's SSH-tunneled transport.
1101  */
1102 static void push_ssh_options(struct argv_array *args, struct argv_array *env,
1103                              enum ssh_variant variant, const char *port,
1104                              enum protocol_version version, int flags)
1105 {
1106         if (variant == VARIANT_SSH &&
1107             version > 0) {
1108                 argv_array_push(args, "-o");
1109                 argv_array_push(args, "SendEnv=" GIT_PROTOCOL_ENVIRONMENT);
1110                 argv_array_pushf(env, GIT_PROTOCOL_ENVIRONMENT "=version=%d",
1111                                  version);
1112         }
1113
1114         if (flags & CONNECT_IPV4) {
1115                 switch (variant) {
1116                 case VARIANT_AUTO:
1117                         BUG("VARIANT_AUTO passed to push_ssh_options");
1118                 case VARIANT_SIMPLE:
1119                         die("ssh variant 'simple' does not support -4");
1120                 case VARIANT_SSH:
1121                 case VARIANT_PLINK:
1122                 case VARIANT_PUTTY:
1123                 case VARIANT_TORTOISEPLINK:
1124                         argv_array_push(args, "-4");
1125                 }
1126         } else if (flags & CONNECT_IPV6) {
1127                 switch (variant) {
1128                 case VARIANT_AUTO:
1129                         BUG("VARIANT_AUTO passed to push_ssh_options");
1130                 case VARIANT_SIMPLE:
1131                         die("ssh variant 'simple' does not support -6");
1132                 case VARIANT_SSH:
1133                 case VARIANT_PLINK:
1134                 case VARIANT_PUTTY:
1135                 case VARIANT_TORTOISEPLINK:
1136                         argv_array_push(args, "-6");
1137                 }
1138         }
1139
1140         if (variant == VARIANT_TORTOISEPLINK)
1141                 argv_array_push(args, "-batch");
1142
1143         if (port) {
1144                 switch (variant) {
1145                 case VARIANT_AUTO:
1146                         BUG("VARIANT_AUTO passed to push_ssh_options");
1147                 case VARIANT_SIMPLE:
1148                         die("ssh variant 'simple' does not support setting port");
1149                 case VARIANT_SSH:
1150                         argv_array_push(args, "-p");
1151                         break;
1152                 case VARIANT_PLINK:
1153                 case VARIANT_PUTTY:
1154                 case VARIANT_TORTOISEPLINK:
1155                         argv_array_push(args, "-P");
1156                 }
1157
1158                 argv_array_push(args, port);
1159         }
1160 }
1161
1162 /* Prepare a child_process for use by Git's SSH-tunneled transport. */
1163 static void fill_ssh_args(struct child_process *conn, const char *ssh_host,
1164                           const char *port, enum protocol_version version,
1165                           int flags)
1166 {
1167         const char *ssh;
1168         enum ssh_variant variant;
1169
1170         if (looks_like_command_line_option(ssh_host))
1171                 die("strange hostname '%s' blocked", ssh_host);
1172
1173         ssh = get_ssh_command();
1174         if (ssh) {
1175                 variant = determine_ssh_variant(ssh, 1);
1176         } else {
1177                 /*
1178                  * GIT_SSH is the no-shell version of
1179                  * GIT_SSH_COMMAND (and must remain so for
1180                  * historical compatibility).
1181                  */
1182                 conn->use_shell = 0;
1183
1184                 ssh = getenv("GIT_SSH");
1185                 if (!ssh)
1186                         ssh = "ssh";
1187                 variant = determine_ssh_variant(ssh, 0);
1188         }
1189
1190         if (variant == VARIANT_AUTO) {
1191                 struct child_process detect = CHILD_PROCESS_INIT;
1192
1193                 detect.use_shell = conn->use_shell;
1194                 detect.no_stdin = detect.no_stdout = detect.no_stderr = 1;
1195
1196                 argv_array_push(&detect.args, ssh);
1197                 argv_array_push(&detect.args, "-G");
1198                 push_ssh_options(&detect.args, &detect.env_array,
1199                                  VARIANT_SSH, port, version, flags);
1200                 argv_array_push(&detect.args, ssh_host);
1201
1202                 variant = run_command(&detect) ? VARIANT_SIMPLE : VARIANT_SSH;
1203         }
1204
1205         argv_array_push(&conn->args, ssh);
1206         push_ssh_options(&conn->args, &conn->env_array, variant, port, version, flags);
1207         argv_array_push(&conn->args, ssh_host);
1208 }
1209
1210 /*
1211  * This returns the dummy child_process `no_fork` if the transport protocol
1212  * does not need fork(2), or a struct child_process object if it does.  Once
1213  * done, finish the connection with finish_connect() with the value returned
1214  * from this function (it is safe to call finish_connect() with NULL to
1215  * support the former case).
1216  *
1217  * If it returns, the connect is successful; it just dies on errors (this
1218  * will hopefully be changed in a libification effort, to return NULL when
1219  * the connection failed).
1220  */
1221 struct child_process *git_connect(int fd[2], const char *url,
1222                                   const char *prog, int flags)
1223 {
1224         char *hostandport, *path;
1225         struct child_process *conn;
1226         enum protocol protocol;
1227         enum protocol_version version = get_protocol_version_config();
1228
1229         /*
1230          * NEEDSWORK: If we are trying to use protocol v2 and we are planning
1231          * to perform a push, then fallback to v0 since the client doesn't know
1232          * how to push yet using v2.
1233          */
1234         if (version == protocol_v2 && !strcmp("git-receive-pack", prog))
1235                 version = protocol_v0;
1236
1237         /* Without this we cannot rely on waitpid() to tell
1238          * what happened to our children.
1239          */
1240         signal(SIGCHLD, SIG_DFL);
1241
1242         protocol = parse_connect_url(url, &hostandport, &path);
1243         if ((flags & CONNECT_DIAG_URL) && (protocol != PROTO_SSH)) {
1244                 printf("Diag: url=%s\n", url ? url : "NULL");
1245                 printf("Diag: protocol=%s\n", prot_name(protocol));
1246                 printf("Diag: hostandport=%s\n", hostandport ? hostandport : "NULL");
1247                 printf("Diag: path=%s\n", path ? path : "NULL");
1248                 conn = NULL;
1249         } else if (protocol == PROTO_GIT) {
1250                 conn = git_connect_git(fd, hostandport, path, prog, version, flags);
1251         } else {
1252                 struct strbuf cmd = STRBUF_INIT;
1253                 const char *const *var;
1254
1255                 conn = xmalloc(sizeof(*conn));
1256                 child_process_init(conn);
1257
1258                 if (looks_like_command_line_option(path))
1259                         die("strange pathname '%s' blocked", path);
1260
1261                 strbuf_addstr(&cmd, prog);
1262                 strbuf_addch(&cmd, ' ');
1263                 sq_quote_buf(&cmd, path);
1264
1265                 /* remove repo-local variables from the environment */
1266                 for (var = local_repo_env; *var; var++)
1267                         argv_array_push(&conn->env_array, *var);
1268
1269                 conn->use_shell = 1;
1270                 conn->in = conn->out = -1;
1271                 if (protocol == PROTO_SSH) {
1272                         char *ssh_host = hostandport;
1273                         const char *port = NULL;
1274                         transport_check_allowed("ssh");
1275                         get_host_and_port(&ssh_host, &port);
1276
1277                         if (!port)
1278                                 port = get_port(ssh_host);
1279
1280                         if (flags & CONNECT_DIAG_URL) {
1281                                 printf("Diag: url=%s\n", url ? url : "NULL");
1282                                 printf("Diag: protocol=%s\n", prot_name(protocol));
1283                                 printf("Diag: userandhost=%s\n", ssh_host ? ssh_host : "NULL");
1284                                 printf("Diag: port=%s\n", port ? port : "NONE");
1285                                 printf("Diag: path=%s\n", path ? path : "NULL");
1286
1287                                 free(hostandport);
1288                                 free(path);
1289                                 free(conn);
1290                                 strbuf_release(&cmd);
1291                                 return NULL;
1292                         }
1293                         fill_ssh_args(conn, ssh_host, port, version, flags);
1294                 } else {
1295                         transport_check_allowed("file");
1296                         if (version > 0) {
1297                                 argv_array_pushf(&conn->env_array, GIT_PROTOCOL_ENVIRONMENT "=version=%d",
1298                                                  version);
1299                         }
1300                 }
1301                 argv_array_push(&conn->args, cmd.buf);
1302
1303                 if (start_command(conn))
1304                         die("unable to fork");
1305
1306                 fd[0] = conn->out; /* read from child's stdout */
1307                 fd[1] = conn->in;  /* write to child's stdin */
1308                 strbuf_release(&cmd);
1309         }
1310         free(hostandport);
1311         free(path);
1312         return conn;
1313 }
1314
1315 int finish_connect(struct child_process *conn)
1316 {
1317         int code;
1318         if (!conn || git_connection_is_socket(conn))
1319                 return 0;
1320
1321         code = finish_command(conn);
1322         free(conn);
1323         return code;
1324 }