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 "oid-array.h"
  13 #include "transport.h"
  14 #include "strbuf.h"
  15 #include "version.h"
  16 #include "protocol.h"
  17 #include "alias.h"
  18 #include "bundle-uri.h"
  19
  20 static char *server_capabilities_v1;
  21 static struct strvec server_capabilities_v2 = STRVEC_INIT;
  22 static const char *next_server_feature_value(const char *feature, int *len, int *offset);
  23
  24 static int check_ref(const char *name, unsigned int flags)
  25 {
  26         if (!flags)
  27                 return 1;
  28
  29         if (!skip_prefix(name, "refs/", &name))
  30                 return 0;
  31
  32         /* REF_NORMAL means that we don't want the magic fake tag refs */
  33         if ((flags & REF_NORMAL) && check_refname_format(name, 0))
  34                 return 0;
  35
  36         /* REF_HEADS means that we want regular branch heads */
  37         if ((flags & REF_HEADS) && starts_with(name, "heads/"))
  38                 return 1;
  39
  40         /* REF_TAGS means that we want tags */
  41         if ((flags & REF_TAGS) && starts_with(name, "tags/"))
  42                 return 1;
  43
  44         /* All type bits clear means that we are ok with anything */
  45         return !(flags & ~REF_NORMAL);
  46 }
  47
  48 int check_ref_type(const struct ref *ref, int flags)
  49 {
  50         return check_ref(ref->name, flags);
  51 }
  52
  53 static NORETURN void die_initial_contact(int unexpected)
  54 {
  55         /*
  56          * A hang-up after seeing some response from the other end
  57          * means that it is unexpected, as we know the other end is
  58          * willing to talk to us.  A hang-up before seeing any
  59          * response does not necessarily mean an ACL problem, though.
  60          */
  61         if (unexpected)
  62                 die(_("the remote end hung up upon initial contact"));
  63         else
  64                 die(_("Could not read from remote repository.\n\n"
  65                       "Please make sure you have the correct access rights\n"
  66                       "and the repository exists."));
  67 }
  68
  69 /* Checks if the server supports the capability 'c' */
  70 int server_supports_v2(const char *c)
  71 {
  72         int i;
  73
  74         for (i = 0; i < server_capabilities_v2.nr; i++) {
  75                 const char *out;
  76                 if (skip_prefix(server_capabilities_v2.v[i], c, &out) &&
  77                     (!*out || *out == '='))
  78                         return 1;
  79         }
  80         return 0;
  81 }
  82
  83 void ensure_server_supports_v2(const char *c)
  84 {
  85         if (!server_supports_v2(c))
  86                 die(_("server doesn't support '%s'"), c);
  87 }
  88
  89 int server_feature_v2(const char *c, const char **v)
  90 {
  91         int i;
  92
  93         for (i = 0; i < server_capabilities_v2.nr; i++) {
  94                 const char *out;
  95                 if (skip_prefix(server_capabilities_v2.v[i], c, &out) &&
  96                     (*out == '=')) {
  97                         *v = out + 1;
  98                         return 1;
  99                 }
 100         }
 101         return 0;
 102 }
 103
 104 int server_supports_feature(const char *c, const char *feature,
 105                             int die_on_error)
 106 {
 107         int i;
 108
 109         for (i = 0; i < server_capabilities_v2.nr; i++) {
 110                 const char *out;
 111                 if (skip_prefix(server_capabilities_v2.v[i], c, &out) &&
 112                     (!*out || *(out++) == '=')) {
 113                         if (parse_feature_request(out, feature))
 114                                 return 1;
 115                         else
 116                                 break;
 117                 }
 118         }
 119
 120         if (die_on_error)
 121                 die(_("server doesn't support feature '%s'"), feature);
 122
 123         return 0;
 124 }
 125
 126 static void process_capabilities_v2(struct packet_reader *reader)
 127 {
 128         while (packet_reader_read(reader) == PACKET_READ_NORMAL)
 129                 strvec_push(&server_capabilities_v2, reader->line);
 130
 131         if (reader->status != PACKET_READ_FLUSH)
 132                 die(_("expected flush after capabilities"));
 133 }
 134
 135 enum protocol_version discover_version(struct packet_reader *reader)
 136 {
 137         enum protocol_version version = protocol_unknown_version;
 138
 139         /*
 140          * Peek the first line of the server's response to
 141          * determine the protocol version the server is speaking.
 142          */
 143         switch (packet_reader_peek(reader)) {
 144         case PACKET_READ_EOF:
 145                 die_initial_contact(0);
 146         case PACKET_READ_FLUSH:
 147         case PACKET_READ_DELIM:
 148         case PACKET_READ_RESPONSE_END:
 149                 version = protocol_v0;
 150                 break;
 151         case PACKET_READ_NORMAL:
 152                 version = determine_protocol_version_client(reader->line);
 153                 break;
 154         }
 155
 156         switch (version) {
 157         case protocol_v2:
 158                 process_capabilities_v2(reader);
 159                 break;
 160         case protocol_v1:
 161                 /* Read the peeked version line */
 162                 packet_reader_read(reader);
 163                 break;
 164         case protocol_v0:
 165                 break;
 166         case protocol_unknown_version:
 167                 BUG("unknown protocol version");
 168         }
 169
 170         trace2_data_intmax("transfer", NULL, "negotiated-version", version);
 171
 172         return version;
 173 }
 174
 175 static void parse_one_symref_info(struct string_list *symref, const char *val, int len)
 176 {
 177         char *sym, *target;
 178         struct string_list_item *item;
 179
 180         if (!len)
 181                 return; /* just "symref" */
 182         /* e.g. "symref=HEAD:refs/heads/master" */
 183         sym = xmemdupz(val, len);
 184         target = strchr(sym, ':');
 185         if (!target)
 186                 /* just "symref=something" */
 187                 goto reject;
 188         *(target++) = '\0';
 189         if (check_refname_format(sym, REFNAME_ALLOW_ONELEVEL) ||
 190             check_refname_format(target, REFNAME_ALLOW_ONELEVEL))
 191                 /* "symref=bogus:pair */
 192                 goto reject;
 193         item = string_list_append_nodup(symref, sym);
 194         item->util = target;
 195         return;
 196 reject:
 197         free(sym);
 198         return;
 199 }
 200
 201 static void annotate_refs_with_symref_info(struct ref *ref)
 202 {
 203         struct string_list symref = STRING_LIST_INIT_DUP;
 204         int offset = 0;
 205
 206         while (1) {
 207                 int len;
 208                 const char *val;
 209
 210                 val = next_server_feature_value("symref", &len, &offset);
 211                 if (!val)
 212                         break;
 213                 parse_one_symref_info(&symref, val, len);
 214         }
 215         string_list_sort(&symref);
 216
 217         for (; ref; ref = ref->next) {
 218                 struct string_list_item *item;
 219                 item = string_list_lookup(&symref, ref->name);
 220                 if (!item)
 221                         continue;
 222                 ref->symref = xstrdup((char *)item->util);
 223         }
 224         string_list_clear(&symref, 0);
 225 }
 226
 227 static void process_capabilities(struct packet_reader *reader, int *linelen)
 228 {
 229         const char *feat_val;
 230         int feat_len;
 231         const char *line = reader->line;
 232         int nul_location = strlen(line);
 233         if (nul_location == *linelen)
 234                 return;
 235         server_capabilities_v1 = xstrdup(line + nul_location + 1);
 236         *linelen = nul_location;
 237
 238         feat_val = server_feature_value("object-format", &feat_len);
 239         if (feat_val) {
 240                 char *hash_name = xstrndup(feat_val, feat_len);
 241                 int hash_algo = hash_algo_by_name(hash_name);
 242                 if (hash_algo != GIT_HASH_UNKNOWN)
 243                         reader->hash_algo = &hash_algos[hash_algo];
 244                 free(hash_name);
 245         } else {
 246                 reader->hash_algo = &hash_algos[GIT_HASH_SHA1];
 247         }
 248 }
 249
 250 static int process_dummy_ref(const struct packet_reader *reader)
 251 {
 252         const char *line = reader->line;
 253         struct object_id oid;
 254         const char *name;
 255
 256         if (parse_oid_hex_algop(line, &oid, &name, reader->hash_algo))
 257                 return 0;
 258         if (*name != ' ')
 259                 return 0;
 260         name++;
 261
 262         return oideq(null_oid(), &oid) && !strcmp(name, "capabilities^{}");
 263 }
 264
 265 static void check_no_capabilities(const char *line, int len)
 266 {
 267         if (strlen(line) != len)
 268                 warning(_("ignoring capabilities after first line '%s'"),
 269                         line + strlen(line));
 270 }
 271
 272 static int process_ref(const struct packet_reader *reader, int len,
 273                        struct ref ***list, unsigned int flags,
 274                        struct oid_array *extra_have)
 275 {
 276         const char *line = reader->line;
 277         struct object_id old_oid;
 278         const char *name;
 279
 280         if (parse_oid_hex_algop(line, &old_oid, &name, reader->hash_algo))
 281                 return 0;
 282         if (*name != ' ')
 283                 return 0;
 284         name++;
 285
 286         if (extra_have && !strcmp(name, ".have")) {
 287                 oid_array_append(extra_have, &old_oid);
 288         } else if (!strcmp(name, "capabilities^{}")) {
 289                 die(_("protocol error: unexpected capabilities^{}"));
 290         } else if (check_ref(name, flags)) {
 291                 struct ref *ref = alloc_ref(name);
 292                 oidcpy(&ref->old_oid, &old_oid);
 293                 **list = ref;
 294                 *list = &ref->next;
 295         }
 296         check_no_capabilities(line, len);
 297         return 1;
 298 }
 299
 300 static int process_shallow(const struct packet_reader *reader, int len,
 301                            struct oid_array *shallow_points)
 302 {
 303         const char *line = reader->line;
 304         const char *arg;
 305         struct object_id old_oid;
 306
 307         if (!skip_prefix(line, "shallow ", &arg))
 308                 return 0;
 309
 310         if (get_oid_hex_algop(arg, &old_oid, reader->hash_algo))
 311                 die(_("protocol error: expected shallow sha-1, got '%s'"), arg);
 312         if (!shallow_points)
 313                 die(_("repository on the other end cannot be shallow"));
 314         oid_array_append(shallow_points, &old_oid);
 315         check_no_capabilities(line, len);
 316         return 1;
 317 }
 318
 319 enum get_remote_heads_state {
 320         EXPECTING_FIRST_REF = 0,
 321         EXPECTING_REF,
 322         EXPECTING_SHALLOW,
 323         EXPECTING_DONE,
 324 };
 325
 326 /*
 327  * Read all the refs from the other end
 328  */
 329 struct ref **get_remote_heads(struct packet_reader *reader,
 330                               struct ref **list, unsigned int flags,
 331                               struct oid_array *extra_have,
 332                               struct oid_array *shallow_points)
 333 {
 334         struct ref **orig_list = list;
 335         int len = 0;
 336         enum get_remote_heads_state state = EXPECTING_FIRST_REF;
 337
 338         *list = NULL;
 339
 340         while (state != EXPECTING_DONE) {
 341                 switch (packet_reader_read(reader)) {
 342                 case PACKET_READ_EOF:
 343                         die_initial_contact(1);
 344                 case PACKET_READ_NORMAL:
 345                         len = reader->pktlen;
 346                         break;
 347                 case PACKET_READ_FLUSH:
 348                         state = EXPECTING_DONE;
 349                         break;
 350                 case PACKET_READ_DELIM:
 351                 case PACKET_READ_RESPONSE_END:
 352                         die(_("invalid packet"));
 353                 }
 354
 355                 switch (state) {
 356                 case EXPECTING_FIRST_REF:
 357                         process_capabilities(reader, &len);
 358                         if (process_dummy_ref(reader)) {
 359                                 state = EXPECTING_SHALLOW;
 360                                 break;
 361                         }
 362                         state = EXPECTING_REF;
 363                         /* fallthrough */
 364                 case EXPECTING_REF:
 365                         if (process_ref(reader, len, &list, flags, extra_have))
 366                                 break;
 367                         state = EXPECTING_SHALLOW;
 368                         /* fallthrough */
 369                 case EXPECTING_SHALLOW:
 370                         if (process_shallow(reader, len, shallow_points))
 371                                 break;
 372                         die(_("protocol error: unexpected '%s'"), reader->line);
 373                 case EXPECTING_DONE:
 374                         break;
 375                 }
 376         }
 377
 378         annotate_refs_with_symref_info(*orig_list);
 379
 380         return list;
 381 }
 382
 383 /* Returns 1 when a valid ref has been added to `list`, 0 otherwise */
 384 static int process_ref_v2(struct packet_reader *reader, struct ref ***list,
 385                           const char **unborn_head_target)
 386 {
 387         int ret = 1;
 388         int i = 0;
 389         struct object_id old_oid;
 390         struct ref *ref;
 391         struct string_list line_sections = STRING_LIST_INIT_DUP;
 392         const char *end;
 393         const char *line = reader->line;
 394
 395         /*
 396          * Ref lines have a number of fields which are space deliminated.  The
 397          * first field is the OID of the ref.  The second field is the ref
 398          * name.  Subsequent fields (symref-target and peeled) are optional and
 399          * don't have a particular order.
 400          */
 401         if (string_list_split(&line_sections, line, ' ', -1) < 2) {
 402                 ret = 0;
 403                 goto out;
 404         }
 405
 406         if (!strcmp("unborn", line_sections.items[i].string)) {
 407                 i++;
 408                 if (unborn_head_target &&
 409                     !strcmp("HEAD", line_sections.items[i++].string)) {
 410                         /*
 411                          * Look for the symref target (if any). If found,
 412                          * return it to the caller.
 413                          */
 414                         for (; i < line_sections.nr; i++) {
 415                                 const char *arg = line_sections.items[i].string;
 416
 417                                 if (skip_prefix(arg, "symref-target:", &arg)) {
 418                                         *unborn_head_target = xstrdup(arg);
 419                                         break;
 420                                 }
 421                         }
 422                 }
 423                 goto out;
 424         }
 425         if (parse_oid_hex_algop(line_sections.items[i++].string, &old_oid, &end, reader->hash_algo) ||
 426             *end) {
 427                 ret = 0;
 428                 goto out;
 429         }
 430
 431         ref = alloc_ref(line_sections.items[i++].string);
 432
 433         memcpy(ref->old_oid.hash, old_oid.hash, reader->hash_algo->rawsz);
 434         **list = ref;
 435         *list = &ref->next;
 436
 437         for (; i < line_sections.nr; i++) {
 438                 const char *arg = line_sections.items[i].string;
 439                 if (skip_prefix(arg, "symref-target:", &arg))
 440                         ref->symref = xstrdup(arg);
 441
 442                 if (skip_prefix(arg, "peeled:", &arg)) {
 443                         struct object_id peeled_oid;
 444                         char *peeled_name;
 445                         struct ref *peeled;
 446                         if (parse_oid_hex_algop(arg, &peeled_oid, &end,
 447                                                 reader->hash_algo) || *end) {
 448                                 ret = 0;
 449                                 goto out;
 450                         }
 451
 452                         peeled_name = xstrfmt("%s^{}", ref->name);
 453                         peeled = alloc_ref(peeled_name);
 454
 455                         memcpy(peeled->old_oid.hash, peeled_oid.hash,
 456                                reader->hash_algo->rawsz);
 457                         **list = peeled;
 458                         *list = &peeled->next;
 459
 460                         free(peeled_name);
 461                 }
 462         }
 463
 464 out:
 465         string_list_clear(&line_sections, 0);
 466         return ret;
 467 }
 468
 469 void check_stateless_delimiter(int stateless_rpc,
 470                               struct packet_reader *reader,
 471                               const char *error)
 472 {
 473         if (!stateless_rpc)
 474                 return; /* not in stateless mode, no delimiter expected */
 475         if (packet_reader_read(reader) != PACKET_READ_RESPONSE_END)
 476                 die("%s", error);
 477 }
 478
 479 static void send_capabilities(int fd_out, struct packet_reader *reader)
 480 {
 481         const char *hash_name;
 482
 483         if (server_supports_v2("agent"))
 484                 packet_write_fmt(fd_out, "agent=%s", git_user_agent_sanitized());
 485
 486         if (server_feature_v2("object-format", &hash_name)) {
 487                 int hash_algo = hash_algo_by_name(hash_name);
 488                 if (hash_algo == GIT_HASH_UNKNOWN)
 489                         die(_("unknown object format '%s' specified by server"), hash_name);
 490                 reader->hash_algo = &hash_algos[hash_algo];
 491                 packet_write_fmt(fd_out, "object-format=%s", reader->hash_algo->name);
 492         } else {
 493                 reader->hash_algo = &hash_algos[GIT_HASH_SHA1];
 494         }
 495 }
 496
 497 int get_remote_bundle_uri(int fd_out, struct packet_reader *reader,
 498                           struct bundle_list *bundles, int stateless_rpc)
 499 {
 500         int line_nr = 1;
 501
 502         /* Assert bundle-uri support */
 503         ensure_server_supports_v2("bundle-uri");
 504
 505         /* (Re-)send capabilities */
 506         send_capabilities(fd_out, reader);
 507
 508         /* Send command */
 509         packet_write_fmt(fd_out, "command=bundle-uri\n");
 510         packet_delim(fd_out);
 511
 512         packet_flush(fd_out);
 513
 514         /* Process response from server */
 515         while (packet_reader_read(reader) == PACKET_READ_NORMAL) {
 516                 const char *line = reader->line;
 517                 line_nr++;
 518
 519                 if (!bundle_uri_parse_line(bundles, line))
 520                         continue;
 521
 522                 return error(_("error on bundle-uri response line %d: %s"),
 523                              line_nr, line);
 524         }
 525
 526         if (reader->status != PACKET_READ_FLUSH)
 527                 return error(_("expected flush after bundle-uri listing"));
 528
 529         /*
 530          * Might die(), but obscure enough that that's OK, e.g. in
 531          * serve.c we'll call BUG() on its equivalent (the
 532          * PACKET_READ_RESPONSE_END check).
 533          */
 534         check_stateless_delimiter(stateless_rpc, reader,
 535                                   _("expected response end packet after ref listing"));
 536
 537         return 0;
 538 }
 539
 540 struct ref **get_remote_refs(int fd_out, struct packet_reader *reader,
 541                              struct ref **list, int for_push,
 542                              struct transport_ls_refs_options *transport_options,
 543                              const struct string_list *server_options,
 544                              int stateless_rpc)
 545 {
 546         int i;
 547         struct strvec *ref_prefixes = transport_options ?
 548                 &transport_options->ref_prefixes : NULL;
 549         const char **unborn_head_target = transport_options ?
 550                 &transport_options->unborn_head_target : NULL;
 551         *list = NULL;
 552
 553         ensure_server_supports_v2("ls-refs");
 554         packet_write_fmt(fd_out, "command=ls-refs\n");
 555
 556         /* Send capabilities */
 557         send_capabilities(fd_out, reader);
 558
 559         if (server_options && server_options->nr) {
 560                 ensure_server_supports_v2("server-option");
 561                 for (i = 0; i < server_options->nr; i++)
 562                         packet_write_fmt(fd_out, "server-option=%s",
 563                                          server_options->items[i].string);
 564         }
 565
 566         packet_delim(fd_out);
 567         /* When pushing we don't want to request the peeled tags */
 568         if (!for_push)
 569                 packet_write_fmt(fd_out, "peel\n");
 570         packet_write_fmt(fd_out, "symrefs\n");
 571         if (server_supports_feature("ls-refs", "unborn", 0))
 572                 packet_write_fmt(fd_out, "unborn\n");
 573         for (i = 0; ref_prefixes && i < ref_prefixes->nr; i++) {
 574                 packet_write_fmt(fd_out, "ref-prefix %s\n",
 575                                  ref_prefixes->v[i]);
 576         }
 577         packet_flush(fd_out);
 578
 579         /* Process response from server */
 580         while (packet_reader_read(reader) == PACKET_READ_NORMAL) {
 581                 if (!process_ref_v2(reader, &list, unborn_head_target))
 582                         die(_("invalid ls-refs response: %s"), reader->line);
 583         }
 584
 585         if (reader->status != PACKET_READ_FLUSH)
 586                 die(_("expected flush after ref listing"));
 587
 588         check_stateless_delimiter(stateless_rpc, reader,
 589                                   _("expected response end packet after ref listing"));
 590
 591         return list;
 592 }
 593
 594 const char *parse_feature_value(const char *feature_list, const char *feature, int *lenp, int *offset)
 595 {
 596         int len;
 597
 598         if (!feature_list)
 599                 return NULL;
 600
 601         len = strlen(feature);
 602         if (offset)
 603                 feature_list += *offset;
 604         while (*feature_list) {
 605                 const char *found = strstr(feature_list, feature);
 606                 if (!found)
 607                         return NULL;
 608                 if (feature_list == found || isspace(found[-1])) {
 609                         const char *value = found + len;
 610                         /* feature with no value (e.g., "thin-pack") */
 611                         if (!*value || isspace(*value)) {
 612                                 if (lenp)
 613                                         *lenp = 0;
 614                                 if (offset)
 615                                         *offset = found + len - feature_list;
 616                                 return value;
 617                         }
 618                         /* feature with a value (e.g., "agent=git/1.2.3") */
 619                         else if (*value == '=') {
 620                                 int end;
 621
 622                                 value++;
 623                                 end = strcspn(value, " \t\n");
 624                                 if (lenp)
 625                                         *lenp = end;
 626                                 if (offset)
 627                                         *offset = value + end - feature_list;
 628                                 return value;
 629                         }
 630                         /*
 631                          * otherwise we matched a substring of another feature;
 632                          * keep looking
 633                          */
 634                 }
 635                 feature_list = found + 1;
 636         }
 637         return NULL;
 638 }
 639
 640 int server_supports_hash(const char *desired, int *feature_supported)
 641 {
 642         int offset = 0;
 643         int len;
 644         const char *hash;
 645
 646         hash = next_server_feature_value("object-format", &len, &offset);
 647         if (feature_supported)
 648                 *feature_supported = !!hash;
 649         if (!hash) {
 650                 hash = hash_algos[GIT_HASH_SHA1].name;
 651                 len = strlen(hash);
 652         }
 653         while (hash) {
 654                 if (!xstrncmpz(desired, hash, len))
 655                         return 1;
 656
 657                 hash = next_server_feature_value("object-format", &len, &offset);
 658         }
 659         return 0;
 660 }
 661
 662 int parse_feature_request(const char *feature_list, const char *feature)
 663 {
 664         return !!parse_feature_value(feature_list, feature, NULL, NULL);
 665 }
 666
 667 static const char *next_server_feature_value(const char *feature, int *len, int *offset)
 668 {
 669         return parse_feature_value(server_capabilities_v1, feature, len, offset);
 670 }
 671
 672 const char *server_feature_value(const char *feature, int *len)
 673 {
 674         return parse_feature_value(server_capabilities_v1, feature, len, NULL);
 675 }
 676
 677 int server_supports(const char *feature)
 678 {
 679         return !!server_feature_value(feature, NULL);
 680 }
 681
 682 enum protocol {
 683         PROTO_LOCAL = 1,
 684         PROTO_FILE,
 685         PROTO_SSH,
 686         PROTO_GIT
 687 };
 688
 689 int url_is_local_not_ssh(const char *url)
 690 {
 691         const char *colon = strchr(url, ':');
 692         const char *slash = strchr(url, '/');
 693         return !colon || (slash && slash < colon) ||
 694                 (has_dos_drive_prefix(url) && is_valid_path(url));
 695 }
 696
 697 static const char *prot_name(enum protocol protocol)
 698 {
 699         switch (protocol) {
 700                 case PROTO_LOCAL:
 701                 case PROTO_FILE:
 702                         return "file";
 703                 case PROTO_SSH:
 704                         return "ssh";
 705                 case PROTO_GIT:
 706                         return "git";
 707                 default:
 708                         return "unknown protocol";
 709         }
 710 }
 711
 712 static enum protocol get_protocol(const char *name)
 713 {
 714         if (!strcmp(name, "ssh"))
 715                 return PROTO_SSH;
 716         if (!strcmp(name, "git"))
 717                 return PROTO_GIT;
 718         if (!strcmp(name, "git+ssh")) /* deprecated - do not use */
 719                 return PROTO_SSH;
 720         if (!strcmp(name, "ssh+git")) /* deprecated - do not use */
 721                 return PROTO_SSH;
 722         if (!strcmp(name, "file"))
 723                 return PROTO_FILE;
 724         die(_("protocol '%s' is not supported"), name);
 725 }
 726
 727 static char *host_end(char **hoststart, int removebrackets)
 728 {
 729         char *host = *hoststart;
 730         char *end;
 731         char *start = strstr(host, "@[");
 732         if (start)
 733                 start++; /* Jump over '@' */
 734         else
 735                 start = host;
 736         if (start[0] == '[') {
 737                 end = strchr(start + 1, ']');
 738                 if (end) {
 739                         if (removebrackets) {
 740                                 *end = 0;
 741                                 memmove(start, start + 1, end - start);
 742                                 end++;
 743                         }
 744                 } else
 745                         end = host;
 746         } else
 747                 end = host;
 748         return end;
 749 }
 750
 751 #define STR_(s) # s
 752 #define STR(s)  STR_(s)
 753
 754 static void get_host_and_port(char **host, const char **port)
 755 {
 756         char *colon, *end;
 757         end = host_end(host, 1);
 758         colon = strchr(end, ':');
 759         if (colon) {
 760                 long portnr = strtol(colon + 1, &end, 10);
 761                 if (end != colon + 1 && *end == '\0' && 0 <= portnr && portnr < 65536) {
 762                         *colon = 0;
 763                         *port = colon + 1;
 764                 } else if (!colon[1]) {
 765                         *colon = 0;
 766                 }
 767         }
 768 }
 769
 770 static void enable_keepalive(int sockfd)
 771 {
 772         int ka = 1;
 773
 774         if (setsockopt(sockfd, SOL_SOCKET, SO_KEEPALIVE, &ka, sizeof(ka)) < 0)
 775                 error_errno(_("unable to set SO_KEEPALIVE on socket"));
 776 }
 777
 778 #ifndef NO_IPV6
 779
 780 static const char *ai_name(const struct addrinfo *ai)
 781 {
 782         static char addr[NI_MAXHOST];
 783         if (getnameinfo(ai->ai_addr, ai->ai_addrlen, addr, sizeof(addr), NULL, 0,
 784                         NI_NUMERICHOST) != 0)
 785                 xsnprintf(addr, sizeof(addr), "(unknown)");
 786
 787         return addr;
 788 }
 789
 790 /*
 791  * Returns a connected socket() fd, or else die()s.
 792  */
 793 static int git_tcp_connect_sock(char *host, int flags)
 794 {
 795         struct strbuf error_message = STRBUF_INIT;
 796         int sockfd = -1;
 797         const char *port = STR(DEFAULT_GIT_PORT);
 798         struct addrinfo hints, *ai0, *ai;
 799         int gai;
 800         int cnt = 0;
 801
 802         get_host_and_port(&host, &port);
 803         if (!*port)
 804                 port = "<none>";
 805
 806         memset(&hints, 0, sizeof(hints));
 807         if (flags & CONNECT_IPV4)
 808                 hints.ai_family = AF_INET;
 809         else if (flags & CONNECT_IPV6)
 810                 hints.ai_family = AF_INET6;
 811         hints.ai_socktype = SOCK_STREAM;
 812         hints.ai_protocol = IPPROTO_TCP;
 813
 814         if (flags & CONNECT_VERBOSE)
 815                 fprintf(stderr, _("Looking up %s ... "), host);
 816
 817         gai = getaddrinfo(host, port, &hints, &ai);
 818         if (gai)
 819                 die(_("unable to look up %s (port %s) (%s)"), host, port, gai_strerror(gai));
 820
 821         if (flags & CONNECT_VERBOSE)
 822                 /* TRANSLATORS: this is the end of "Looking up %s ... " */
 823                 fprintf(stderr, _("done.\nConnecting to %s (port %s) ... "), host, port);
 824
 825         for (ai0 = ai; ai; ai = ai->ai_next, cnt++) {
 826                 sockfd = socket(ai->ai_family,
 827                                 ai->ai_socktype, ai->ai_protocol);
 828                 if ((sockfd < 0) ||
 829                     (connect(sockfd, ai->ai_addr, ai->ai_addrlen) < 0)) {
 830                         strbuf_addf(&error_message, "%s[%d: %s]: errno=%s\n",
 831                                     host, cnt, ai_name(ai), strerror(errno));
 832                         if (0 <= sockfd)
 833                                 close(sockfd);
 834                         sockfd = -1;
 835                         continue;
 836                 }
 837                 if (flags & CONNECT_VERBOSE)
 838                         fprintf(stderr, "%s ", ai_name(ai));
 839                 break;
 840         }
 841
 842         freeaddrinfo(ai0);
 843
 844         if (sockfd < 0)
 845                 die(_("unable to connect to %s:\n%s"), host, error_message.buf);
 846
 847         enable_keepalive(sockfd);
 848
 849         if (flags & CONNECT_VERBOSE)
 850                 /* TRANSLATORS: this is the end of "Connecting to %s (port %s) ... " */
 851                 fprintf_ln(stderr, _("done."));
 852
 853         strbuf_release(&error_message);
 854
 855         return sockfd;
 856 }
 857
 858 #else /* NO_IPV6 */
 859
 860 /*
 861  * Returns a connected socket() fd, or else die()s.
 862  */
 863 static int git_tcp_connect_sock(char *host, int flags)
 864 {
 865         struct strbuf error_message = STRBUF_INIT;
 866         int sockfd = -1;
 867         const char *port = STR(DEFAULT_GIT_PORT);
 868         char *ep;
 869         struct hostent *he;
 870         struct sockaddr_in sa;
 871         char **ap;
 872         unsigned int nport;
 873         int cnt;
 874
 875         get_host_and_port(&host, &port);
 876
 877         if (flags & CONNECT_VERBOSE)
 878                 fprintf(stderr, _("Looking up %s ... "), host);
 879
 880         he = gethostbyname(host);
 881         if (!he)
 882                 die(_("unable to look up %s (%s)"), host, hstrerror(h_errno));
 883         nport = strtoul(port, &ep, 10);
 884         if ( ep == port || *ep ) {
 885                 /* Not numeric */
 886                 struct servent *se = getservbyname(port,"tcp");
 887                 if ( !se )
 888                         die(_("unknown port %s"), port);
 889                 nport = se->s_port;
 890         }
 891
 892         if (flags & CONNECT_VERBOSE)
 893                 /* TRANSLATORS: this is the end of "Looking up %s ... " */
 894                 fprintf(stderr, _("done.\nConnecting to %s (port %s) ... "), host, port);
 895
 896         for (cnt = 0, ap = he->h_addr_list; *ap; ap++, cnt++) {
 897                 memset(&sa, 0, sizeof sa);
 898                 sa.sin_family = he->h_addrtype;
 899                 sa.sin_port = htons(nport);
 900                 memcpy(&sa.sin_addr, *ap, he->h_length);
 901
 902                 sockfd = socket(he->h_addrtype, SOCK_STREAM, 0);
 903                 if ((sockfd < 0) ||
 904                     connect(sockfd, (struct sockaddr *)&sa, sizeof sa) < 0) {
 905                         strbuf_addf(&error_message, "%s[%d: %s]: errno=%s\n",
 906                                 host,
 907                                 cnt,
 908                                 inet_ntoa(*(struct in_addr *)&sa.sin_addr),
 909                                 strerror(errno));
 910                         if (0 <= sockfd)
 911                                 close(sockfd);
 912                         sockfd = -1;
 913                         continue;
 914                 }
 915                 if (flags & CONNECT_VERBOSE)
 916                         fprintf(stderr, "%s ",
 917                                 inet_ntoa(*(struct in_addr *)&sa.sin_addr));
 918                 break;
 919         }
 920
 921         if (sockfd < 0)
 922                 die(_("unable to connect to %s:\n%s"), host, error_message.buf);
 923
 924         enable_keepalive(sockfd);
 925
 926         if (flags & CONNECT_VERBOSE)
 927                 /* TRANSLATORS: this is the end of "Connecting to %s (port %s) ... " */
 928                 fprintf_ln(stderr, _("done."));
 929
 930         return sockfd;
 931 }
 932
 933 #endif /* NO_IPV6 */
 934
 935
 936 /*
 937  * Dummy child_process returned by git_connect() if the transport protocol
 938  * does not need fork(2).
 939  */
 940 static struct child_process no_fork = CHILD_PROCESS_INIT;
 941
 942 int git_connection_is_socket(struct child_process *conn)
 943 {
 944         return conn == &no_fork;
 945 }
 946
 947 static struct child_process *git_tcp_connect(int fd[2], char *host, int flags)
 948 {
 949         int sockfd = git_tcp_connect_sock(host, flags);
 950
 951         fd[0] = sockfd;
 952         fd[1] = dup(sockfd);
 953
 954         return &no_fork;
 955 }
 956
 957
 958 static char *git_proxy_command;
 959
 960 static int git_proxy_command_options(const char *var, const char *value,
 961                 void *cb)
 962 {
 963         if (!strcmp(var, "core.gitproxy")) {
 964                 const char *for_pos;
 965                 int matchlen = -1;
 966                 int hostlen;
 967                 const char *rhost_name = cb;
 968                 int rhost_len = strlen(rhost_name);
 969
 970                 if (git_proxy_command)
 971                         return 0;
 972                 if (!value)
 973                         return config_error_nonbool(var);
 974                 /* [core]
 975                  * ;# matches www.kernel.org as well
 976                  * gitproxy = netcatter-1 for kernel.org
 977                  * gitproxy = netcatter-2 for sample.xz
 978                  * gitproxy = netcatter-default
 979                  */
 980                 for_pos = strstr(value, " for ");
 981                 if (!for_pos)
 982                         /* matches everybody */
 983                         matchlen = strlen(value);
 984                 else {
 985                         hostlen = strlen(for_pos + 5);
 986                         if (rhost_len < hostlen)
 987                                 matchlen = -1;
 988                         else if (!strncmp(for_pos + 5,
 989                                           rhost_name + rhost_len - hostlen,
 990                                           hostlen) &&
 991                                  ((rhost_len == hostlen) ||
 992                                   rhost_name[rhost_len - hostlen -1] == '.'))
 993                                 matchlen = for_pos - value;
 994                         else
 995                                 matchlen = -1;
 996                 }
 997                 if (0 <= matchlen) {
 998                         /* core.gitproxy = none for kernel.org */
 999                         if (matchlen == 4 &&
1000                             !memcmp(value, "none", 4))
1001                                 matchlen = 0;
1002                         git_proxy_command = xmemdupz(value, matchlen);
1003                 }
1004                 return 0;
1005         }
1006
1007         return git_default_config(var, value, cb);
1008 }
1009
1010 static int git_use_proxy(const char *host)
1011 {
1012         git_proxy_command = getenv("GIT_PROXY_COMMAND");
1013         git_config(git_proxy_command_options, (void*)host);
1014         return (git_proxy_command && *git_proxy_command);
1015 }
1016
1017 static struct child_process *git_proxy_connect(int fd[2], char *host)
1018 {
1019         const char *port = STR(DEFAULT_GIT_PORT);
1020         struct child_process *proxy;
1021
1022         get_host_and_port(&host, &port);
1023
1024         if (looks_like_command_line_option(host))
1025                 die(_("strange hostname '%s' blocked"), host);
1026         if (looks_like_command_line_option(port))
1027                 die(_("strange port '%s' blocked"), port);
1028
1029         proxy = xmalloc(sizeof(*proxy));
1030         child_process_init(proxy);
1031         strvec_push(&proxy->args, git_proxy_command);
1032         strvec_push(&proxy->args, host);
1033         strvec_push(&proxy->args, port);
1034         proxy->in = -1;
1035         proxy->out = -1;
1036         if (start_command(proxy))
1037                 die(_("cannot start proxy %s"), git_proxy_command);
1038         fd[0] = proxy->out; /* read from proxy stdout */
1039         fd[1] = proxy->in;  /* write to proxy stdin */
1040         return proxy;
1041 }
1042
1043 static char *get_port(char *host)
1044 {
1045         char *end;
1046         char *p = strchr(host, ':');
1047
1048         if (p) {
1049                 long port = strtol(p + 1, &end, 10);
1050                 if (end != p + 1 && *end == '\0' && 0 <= port && port < 65536) {
1051                         *p = '\0';
1052                         return p+1;
1053                 }
1054         }
1055
1056         return NULL;
1057 }
1058
1059 /*
1060  * Extract protocol and relevant parts from the specified connection URL.
1061  * The caller must free() the returned strings.
1062  */
1063 static enum protocol parse_connect_url(const char *url_orig, char **ret_host,
1064                                        char **ret_path)
1065 {
1066         char *url;
1067         char *host, *path;
1068         char *end;
1069         int separator = '/';
1070         enum protocol protocol = PROTO_LOCAL;
1071
1072         if (is_url(url_orig))
1073                 url = url_decode(url_orig);
1074         else
1075                 url = xstrdup(url_orig);
1076
1077         host = strstr(url, "://");
1078         if (host) {
1079                 *host = '\0';
1080                 protocol = get_protocol(url);
1081                 host += 3;
1082         } else {
1083                 host = url;
1084                 if (!url_is_local_not_ssh(url)) {
1085                         protocol = PROTO_SSH;
1086                         separator = ':';
1087                 }
1088         }
1089
1090         /*
1091          * Don't do destructive transforms as protocol code does
1092          * '[]' unwrapping in get_host_and_port()
1093          */
1094         end = host_end(&host, 0);
1095
1096         if (protocol == PROTO_LOCAL)
1097                 path = end;
1098         else if (protocol == PROTO_FILE && *host != '/' &&
1099                  !has_dos_drive_prefix(host) &&
1100                  offset_1st_component(host - 2) > 1)
1101                 path = host - 2; /* include the leading "//" */
1102         else if (protocol == PROTO_FILE && has_dos_drive_prefix(end))
1103                 path = end; /* "file://$(pwd)" may be "file://C:/projects/repo" */
1104         else
1105                 path = strchr(end, separator);
1106
1107         if (!path || !*path)
1108                 die(_("no path specified; see 'git help pull' for valid url syntax"));
1109
1110         /*
1111          * null-terminate hostname and point path to ~ for URL's like this:
1112          *    ssh://host.xz/~user/repo
1113          */
1114
1115         end = path; /* Need to \0 terminate host here */
1116         if (separator == ':')
1117                 path++; /* path starts after ':' */
1118         if (protocol == PROTO_GIT || protocol == PROTO_SSH) {
1119                 if (path[1] == '~')
1120                         path++;
1121         }
1122
1123         path = xstrdup(path);
1124         *end = '\0';
1125
1126         *ret_host = xstrdup(host);
1127         *ret_path = path;
1128         free(url);
1129         return protocol;
1130 }
1131
1132 static const char *get_ssh_command(void)
1133 {
1134         const char *ssh;
1135
1136         if ((ssh = getenv("GIT_SSH_COMMAND")))
1137                 return ssh;
1138
1139         if (!git_config_get_string_tmp("core.sshcommand", &ssh))
1140                 return ssh;
1141
1142         return NULL;
1143 }
1144
1145 enum ssh_variant {
1146         VARIANT_AUTO,
1147         VARIANT_SIMPLE,
1148         VARIANT_SSH,
1149         VARIANT_PLINK,
1150         VARIANT_PUTTY,
1151         VARIANT_TORTOISEPLINK,
1152 };
1153
1154 static void override_ssh_variant(enum ssh_variant *ssh_variant)
1155 {
1156         const char *variant = getenv("GIT_SSH_VARIANT");
1157
1158         if (!variant && git_config_get_string_tmp("ssh.variant", &variant))
1159                 return;
1160
1161         if (!strcmp(variant, "auto"))
1162                 *ssh_variant = VARIANT_AUTO;
1163         else if (!strcmp(variant, "plink"))
1164                 *ssh_variant = VARIANT_PLINK;
1165         else if (!strcmp(variant, "putty"))
1166                 *ssh_variant = VARIANT_PUTTY;
1167         else if (!strcmp(variant, "tortoiseplink"))
1168                 *ssh_variant = VARIANT_TORTOISEPLINK;
1169         else if (!strcmp(variant, "simple"))
1170                 *ssh_variant = VARIANT_SIMPLE;
1171         else
1172                 *ssh_variant = VARIANT_SSH;
1173 }
1174
1175 static enum ssh_variant determine_ssh_variant(const char *ssh_command,
1176                                               int is_cmdline)
1177 {
1178         enum ssh_variant ssh_variant = VARIANT_AUTO;
1179         const char *variant;
1180         char *p = NULL;
1181
1182         override_ssh_variant(&ssh_variant);
1183
1184         if (ssh_variant != VARIANT_AUTO)
1185                 return ssh_variant;
1186
1187         if (!is_cmdline) {
1188                 p = xstrdup(ssh_command);
1189                 variant = basename(p);
1190         } else {
1191                 const char **ssh_argv;
1192
1193                 p = xstrdup(ssh_command);
1194                 if (split_cmdline(p, &ssh_argv) > 0) {
1195                         variant = basename((char *)ssh_argv[0]);
1196                         /*
1197                          * At this point, variant points into the buffer
1198                          * referenced by p, hence we do not need ssh_argv
1199                          * any longer.
1200                          */
1201                         free(ssh_argv);
1202                 } else {
1203                         free(p);
1204                         return ssh_variant;
1205                 }
1206         }
1207
1208         if (!strcasecmp(variant, "ssh") ||
1209             !strcasecmp(variant, "ssh.exe"))
1210                 ssh_variant = VARIANT_SSH;
1211         else if (!strcasecmp(variant, "plink") ||
1212                  !strcasecmp(variant, "plink.exe"))
1213                 ssh_variant = VARIANT_PLINK;
1214         else if (!strcasecmp(variant, "tortoiseplink") ||
1215                  !strcasecmp(variant, "tortoiseplink.exe"))
1216                 ssh_variant = VARIANT_TORTOISEPLINK;
1217
1218         free(p);
1219         return ssh_variant;
1220 }
1221
1222 /*
1223  * Open a connection using Git's native protocol.
1224  *
1225  * The caller is responsible for freeing hostandport, but this function may
1226  * modify it (for example, to truncate it to remove the port part).
1227  */
1228 static struct child_process *git_connect_git(int fd[2], char *hostandport,
1229                                              const char *path, const char *prog,
1230                                              enum protocol_version version,
1231                                              int flags)
1232 {
1233         struct child_process *conn;
1234         struct strbuf request = STRBUF_INIT;
1235         /*
1236          * Set up virtual host information based on where we will
1237          * connect, unless the user has overridden us in
1238          * the environment.
1239          */
1240         char *target_host = getenv("GIT_OVERRIDE_VIRTUAL_HOST");
1241         if (target_host)
1242                 target_host = xstrdup(target_host);
1243         else
1244                 target_host = xstrdup(hostandport);
1245
1246         transport_check_allowed("git");
1247         if (strchr(target_host, '\n') || strchr(path, '\n'))
1248                 die(_("newline is forbidden in git:// hosts and repo paths"));
1249
1250         /*
1251          * These underlying connection commands die() if they
1252          * cannot connect.
1253          */
1254         if (git_use_proxy(hostandport))
1255                 conn = git_proxy_connect(fd, hostandport);
1256         else
1257                 conn = git_tcp_connect(fd, hostandport, flags);
1258         /*
1259          * Separate original protocol components prog and path
1260          * from extended host header with a NUL byte.
1261          *
1262          * Note: Do not add any other headers here!  Doing so
1263          * will cause older git-daemon servers to crash.
1264          */
1265         strbuf_addf(&request,
1266                     "%s %s%chost=%s%c",
1267                     prog, path, 0,
1268                     target_host, 0);
1269
1270         /* If using a new version put that stuff here after a second null byte */
1271         if (version > 0) {
1272                 strbuf_addch(&request, '\0');
1273                 strbuf_addf(&request, "version=%d%c",
1274                             version, '\0');
1275         }
1276
1277         packet_write(fd[1], request.buf, request.len);
1278
1279         free(target_host);
1280         strbuf_release(&request);
1281         return conn;
1282 }
1283
1284 /*
1285  * Append the appropriate environment variables to `env` and options to
1286  * `args` for running ssh in Git's SSH-tunneled transport.
1287  */
1288 static void push_ssh_options(struct strvec *args, struct strvec *env,
1289                              enum ssh_variant variant, const char *port,
1290                              enum protocol_version version, int flags)
1291 {
1292         if (variant == VARIANT_SSH &&
1293             version > 0) {
1294                 strvec_push(args, "-o");
1295                 strvec_push(args, "SendEnv=" GIT_PROTOCOL_ENVIRONMENT);
1296                 strvec_pushf(env, GIT_PROTOCOL_ENVIRONMENT "=version=%d",
1297                              version);
1298         }
1299
1300         if (flags & CONNECT_IPV4) {
1301                 switch (variant) {
1302                 case VARIANT_AUTO:
1303                         BUG("VARIANT_AUTO passed to push_ssh_options");
1304                 case VARIANT_SIMPLE:
1305                         die(_("ssh variant 'simple' does not support -4"));
1306                 case VARIANT_SSH:
1307                 case VARIANT_PLINK:
1308                 case VARIANT_PUTTY:
1309                 case VARIANT_TORTOISEPLINK:
1310                         strvec_push(args, "-4");
1311                 }
1312         } else if (flags & CONNECT_IPV6) {
1313                 switch (variant) {
1314                 case VARIANT_AUTO:
1315                         BUG("VARIANT_AUTO passed to push_ssh_options");
1316                 case VARIANT_SIMPLE:
1317                         die(_("ssh variant 'simple' does not support -6"));
1318                 case VARIANT_SSH:
1319                 case VARIANT_PLINK:
1320                 case VARIANT_PUTTY:
1321                 case VARIANT_TORTOISEPLINK:
1322                         strvec_push(args, "-6");
1323                 }
1324         }
1325
1326         if (variant == VARIANT_TORTOISEPLINK)
1327                 strvec_push(args, "-batch");
1328
1329         if (port) {
1330                 switch (variant) {
1331                 case VARIANT_AUTO:
1332                         BUG("VARIANT_AUTO passed to push_ssh_options");
1333                 case VARIANT_SIMPLE:
1334                         die(_("ssh variant 'simple' does not support setting port"));
1335                 case VARIANT_SSH:
1336                         strvec_push(args, "-p");
1337                         break;
1338                 case VARIANT_PLINK:
1339                 case VARIANT_PUTTY:
1340                 case VARIANT_TORTOISEPLINK:
1341                         strvec_push(args, "-P");
1342                 }
1343
1344                 strvec_push(args, port);
1345         }
1346 }
1347
1348 /* Prepare a child_process for use by Git's SSH-tunneled transport. */
1349 static void fill_ssh_args(struct child_process *conn, const char *ssh_host,
1350                           const char *port, enum protocol_version version,
1351                           int flags)
1352 {
1353         const char *ssh;
1354         enum ssh_variant variant;
1355
1356         if (looks_like_command_line_option(ssh_host))
1357                 die(_("strange hostname '%s' blocked"), ssh_host);
1358
1359         ssh = get_ssh_command();
1360         if (ssh) {
1361                 variant = determine_ssh_variant(ssh, 1);
1362         } else {
1363                 /*
1364                  * GIT_SSH is the no-shell version of
1365                  * GIT_SSH_COMMAND (and must remain so for
1366                  * historical compatibility).
1367                  */
1368                 conn->use_shell = 0;
1369
1370                 ssh = getenv("GIT_SSH");
1371                 if (!ssh)
1372                         ssh = "ssh";
1373                 variant = determine_ssh_variant(ssh, 0);
1374         }
1375
1376         if (variant == VARIANT_AUTO) {
1377                 struct child_process detect = CHILD_PROCESS_INIT;
1378
1379                 detect.use_shell = conn->use_shell;
1380                 detect.no_stdin = detect.no_stdout = detect.no_stderr = 1;
1381
1382                 strvec_push(&detect.args, ssh);
1383                 strvec_push(&detect.args, "-G");
1384                 push_ssh_options(&detect.args, &detect.env,
1385                                  VARIANT_SSH, port, version, flags);
1386                 strvec_push(&detect.args, ssh_host);
1387
1388                 variant = run_command(&detect) ? VARIANT_SIMPLE : VARIANT_SSH;
1389         }
1390
1391         strvec_push(&conn->args, ssh);
1392         push_ssh_options(&conn->args, &conn->env, variant, port, version,
1393                          flags);
1394         strvec_push(&conn->args, ssh_host);
1395 }
1396
1397 /*
1398  * This returns the dummy child_process `no_fork` if the transport protocol
1399  * does not need fork(2), or a struct child_process object if it does.  Once
1400  * done, finish the connection with finish_connect() with the value returned
1401  * from this function (it is safe to call finish_connect() with NULL to
1402  * support the former case).
1403  *
1404  * If it returns, the connect is successful; it just dies on errors (this
1405  * will hopefully be changed in a libification effort, to return NULL when
1406  * the connection failed).
1407  */
1408 struct child_process *git_connect(int fd[2], const char *url,
1409                                   const char *prog, int flags)
1410 {
1411         char *hostandport, *path;
1412         struct child_process *conn;
1413         enum protocol protocol;
1414         enum protocol_version version = get_protocol_version_config();
1415
1416         /*
1417          * NEEDSWORK: If we are trying to use protocol v2 and we are planning
1418          * to perform a push, then fallback to v0 since the client doesn't know
1419          * how to push yet using v2.
1420          */
1421         if (version == protocol_v2 && !strcmp("git-receive-pack", prog))
1422                 version = protocol_v0;
1423
1424         /* Without this we cannot rely on waitpid() to tell
1425          * what happened to our children.
1426          */
1427         signal(SIGCHLD, SIG_DFL);
1428
1429         protocol = parse_connect_url(url, &hostandport, &path);
1430         if ((flags & CONNECT_DIAG_URL) && (protocol != PROTO_SSH)) {
1431                 printf("Diag: url=%s\n", url ? url : "NULL");
1432                 printf("Diag: protocol=%s\n", prot_name(protocol));
1433                 printf("Diag: hostandport=%s\n", hostandport ? hostandport : "NULL");
1434                 printf("Diag: path=%s\n", path ? path : "NULL");
1435                 conn = NULL;
1436         } else if (protocol == PROTO_GIT) {
1437                 conn = git_connect_git(fd, hostandport, path, prog, version, flags);
1438                 conn->trace2_child_class = "transport/git";
1439         } else {
1440                 struct strbuf cmd = STRBUF_INIT;
1441                 const char *const *var;
1442
1443                 conn = xmalloc(sizeof(*conn));
1444                 child_process_init(conn);
1445
1446                 if (looks_like_command_line_option(path))
1447                         die(_("strange pathname '%s' blocked"), path);
1448
1449                 strbuf_addstr(&cmd, prog);
1450                 strbuf_addch(&cmd, ' ');
1451                 sq_quote_buf(&cmd, path);
1452
1453                 /* remove repo-local variables from the environment */
1454                 for (var = local_repo_env; *var; var++)
1455                         strvec_push(&conn->env, *var);
1456
1457                 conn->use_shell = 1;
1458                 conn->in = conn->out = -1;
1459                 if (protocol == PROTO_SSH) {
1460                         char *ssh_host = hostandport;
1461                         const char *port = NULL;
1462                         transport_check_allowed("ssh");
1463                         get_host_and_port(&ssh_host, &port);
1464
1465                         if (!port)
1466                                 port = get_port(ssh_host);
1467
1468                         if (flags & CONNECT_DIAG_URL) {
1469                                 printf("Diag: url=%s\n", url ? url : "NULL");
1470                                 printf("Diag: protocol=%s\n", prot_name(protocol));
1471                                 printf("Diag: userandhost=%s\n", ssh_host ? ssh_host : "NULL");
1472                                 printf("Diag: port=%s\n", port ? port : "NONE");
1473                                 printf("Diag: path=%s\n", path ? path : "NULL");
1474
1475                                 free(hostandport);
1476                                 free(path);
1477                                 free(conn);
1478                                 strbuf_release(&cmd);
1479                                 return NULL;
1480                         }
1481                         conn->trace2_child_class = "transport/ssh";
1482                         fill_ssh_args(conn, ssh_host, port, version, flags);
1483                 } else {
1484                         transport_check_allowed("file");
1485                         conn->trace2_child_class = "transport/file";
1486                         if (version > 0) {
1487                                 strvec_pushf(&conn->env,
1488                                              GIT_PROTOCOL_ENVIRONMENT "=version=%d",
1489                                              version);
1490                         }
1491                 }
1492                 strvec_push(&conn->args, cmd.buf);
1493
1494                 if (start_command(conn))
1495                         die(_("unable to fork"));
1496
1497                 fd[0] = conn->out; /* read from child's stdout */
1498                 fd[1] = conn->in;  /* write to child's stdin */
1499                 strbuf_release(&cmd);
1500         }
1501         free(hostandport);
1502         free(path);
1503         return conn;
1504 }
1505
1506 int finish_connect(struct child_process *conn)
1507 {
1508         int code;
1509         if (!conn || git_connection_is_socket(conn))
1510                 return 0;
1511
1512         code = finish_command(conn);
1513         free(conn);
1514         return code;
1515 }