connect.c

   1 #include "git-compat-util.h"
   2 #include "cache.h"
   3 #include "config.h"
   4 #include "gettext.h"
   5 #include "hex.h"
   6 #include "pkt-line.h"
   7 #include "quote.h"
   8 #include "refs.h"
   9 #include "run-command.h"
  10 #include "remote.h"
  11 #include "connect.h"
  12 #include "url.h"
  13 #include "string-list.h"
  14 #include "oid-array.h"
  15 #include "transport.h"
  16 #include "strbuf.h"
  17 #include "version.h"
  18 #include "protocol.h"
  19 #include "alias.h"
  20 #include "bundle-uri.h"
  21
  22 static char *server_capabilities_v1;
  23 static struct strvec server_capabilities_v2 = STRVEC_INIT;
  24 static const char *next_server_feature_value(const char *feature, int *len, int *offset);
  25
  26 static int check_ref(const char *name, unsigned int flags)
  27 {
  28         if (!flags)
  29                 return 1;
  30
  31         if (!skip_prefix(name, "refs/", &name))
  32                 return 0;
  33
  34         /* REF_NORMAL means that we don't want the magic fake tag refs */
  35         if ((flags & REF_NORMAL) && check_refname_format(name,
  36                                                          REFNAME_ALLOW_ONELEVEL))
  37                 return 0;
  38
  39         /* REF_HEADS means that we want regular branch heads */
  40         if ((flags & REF_HEADS) && starts_with(name, "heads/"))
  41                 return 1;
  42
  43         /* REF_TAGS means that we want tags */
  44         if ((flags & REF_TAGS) && starts_with(name, "tags/"))
  45                 return 1;
  46
  47         /* All type bits clear means that we are ok with anything */
  48         return !(flags & ~REF_NORMAL);
  49 }
  50
  51 int check_ref_type(const struct ref *ref, int flags)
  52 {
  53         return check_ref(ref->name, flags);
  54 }
  55
  56 static NORETURN void die_initial_contact(int unexpected)
  57 {
  58         /*
  59          * A hang-up after seeing some response from the other end
  60          * means that it is unexpected, as we know the other end is
  61          * willing to talk to us.  A hang-up before seeing any
  62          * response does not necessarily mean an ACL problem, though.
  63          */
  64         if (unexpected)
  65                 die(_("the remote end hung up upon initial contact"));
  66         else
  67                 die(_("Could not read from remote repository.\n\n"
  68                       "Please make sure you have the correct access rights\n"
  69                       "and the repository exists."));
  70 }
  71
  72 /* Checks if the server supports the capability 'c' */
  73 int server_supports_v2(const char *c)
  74 {
  75         int i;
  76
  77         for (i = 0; i < server_capabilities_v2.nr; i++) {
  78                 const char *out;
  79                 if (skip_prefix(server_capabilities_v2.v[i], c, &out) &&
  80                     (!*out || *out == '='))
  81                         return 1;
  82         }
  83         return 0;
  84 }
  85
  86 void ensure_server_supports_v2(const char *c)
  87 {
  88         if (!server_supports_v2(c))
  89                 die(_("server doesn't support '%s'"), c);
  90 }
  91
  92 int server_feature_v2(const char *c, const char **v)
  93 {
  94         int i;
  95
  96         for (i = 0; i < server_capabilities_v2.nr; i++) {
  97                 const char *out;
  98                 if (skip_prefix(server_capabilities_v2.v[i], c, &out) &&
  99                     (*out == '=')) {
 100                         *v = out + 1;
 101                         return 1;
 102                 }
 103         }
 104         return 0;
 105 }
 106
 107 int server_supports_feature(const char *c, const char *feature,
 108                             int die_on_error)
 109 {
 110         int i;
 111
 112         for (i = 0; i < server_capabilities_v2.nr; i++) {
 113                 const char *out;
 114                 if (skip_prefix(server_capabilities_v2.v[i], c, &out) &&
 115                     (!*out || *(out++) == '=')) {
 116                         if (parse_feature_request(out, feature))
 117                                 return 1;
 118                         else
 119                                 break;
 120                 }
 121         }
 122
 123         if (die_on_error)
 124                 die(_("server doesn't support feature '%s'"), feature);
 125
 126         return 0;
 127 }
 128
 129 static void process_capabilities_v2(struct packet_reader *reader)
 130 {
 131         while (packet_reader_read(reader) == PACKET_READ_NORMAL)
 132                 strvec_push(&server_capabilities_v2, reader->line);
 133
 134         if (reader->status != PACKET_READ_FLUSH)
 135                 die(_("expected flush after capabilities"));
 136 }
 137
 138 enum protocol_version discover_version(struct packet_reader *reader)
 139 {
 140         enum protocol_version version = protocol_unknown_version;
 141
 142         /*
 143          * Peek the first line of the server's response to
 144          * determine the protocol version the server is speaking.
 145          */
 146         switch (packet_reader_peek(reader)) {
 147         case PACKET_READ_EOF:
 148                 die_initial_contact(0);
 149         case PACKET_READ_FLUSH:
 150         case PACKET_READ_DELIM:
 151         case PACKET_READ_RESPONSE_END:
 152                 version = protocol_v0;
 153                 break;
 154         case PACKET_READ_NORMAL:
 155                 version = determine_protocol_version_client(reader->line);
 156                 break;
 157         }
 158
 159         switch (version) {
 160         case protocol_v2:
 161                 process_capabilities_v2(reader);
 162                 break;
 163         case protocol_v1:
 164                 /* Read the peeked version line */
 165                 packet_reader_read(reader);
 166                 break;
 167         case protocol_v0:
 168                 break;
 169         case protocol_unknown_version:
 170                 BUG("unknown protocol version");
 171         }
 172
 173         trace2_data_intmax("transfer", NULL, "negotiated-version", version);
 174
 175         return version;
 176 }
 177
 178 static void parse_one_symref_info(struct string_list *symref, const char *val, int len)
 179 {
 180         char *sym, *target;
 181         struct string_list_item *item;
 182
 183         if (!len)
 184                 return; /* just "symref" */
 185         /* e.g. "symref=HEAD:refs/heads/master" */
 186         sym = xmemdupz(val, len);
 187         target = strchr(sym, ':');
 188         if (!target)
 189                 /* just "symref=something" */
 190                 goto reject;
 191         *(target++) = '\0';
 192         if (check_refname_format(sym, REFNAME_ALLOW_ONELEVEL) ||
 193             check_refname_format(target, REFNAME_ALLOW_ONELEVEL))
 194                 /* "symref=bogus:pair */
 195                 goto reject;
 196         item = string_list_append_nodup(symref, sym);
 197         item->util = target;
 198         return;
 199 reject:
 200         free(sym);
 201         return;
 202 }
 203
 204 static void annotate_refs_with_symref_info(struct ref *ref)
 205 {
 206         struct string_list symref = STRING_LIST_INIT_DUP;
 207         int offset = 0;
 208
 209         while (1) {
 210                 int len;
 211                 const char *val;
 212
 213                 val = next_server_feature_value("symref", &len, &offset);
 214                 if (!val)
 215                         break;
 216                 parse_one_symref_info(&symref, val, len);
 217         }
 218         string_list_sort(&symref);
 219
 220         for (; ref; ref = ref->next) {
 221                 struct string_list_item *item;
 222                 item = string_list_lookup(&symref, ref->name);
 223                 if (!item)
 224                         continue;
 225                 ref->symref = xstrdup((char *)item->util);
 226         }
 227         string_list_clear(&symref, 0);
 228 }
 229
 230 static void process_capabilities(struct packet_reader *reader, int *linelen)
 231 {
 232         const char *feat_val;
 233         int feat_len;
 234         const char *line = reader->line;
 235         int nul_location = strlen(line);
 236         if (nul_location == *linelen)
 237                 return;
 238         server_capabilities_v1 = xstrdup(line + nul_location + 1);
 239         *linelen = nul_location;
 240
 241         feat_val = server_feature_value("object-format", &feat_len);
 242         if (feat_val) {
 243                 char *hash_name = xstrndup(feat_val, feat_len);
 244                 int hash_algo = hash_algo_by_name(hash_name);
 245                 if (hash_algo != GIT_HASH_UNKNOWN)
 246                         reader->hash_algo = &hash_algos[hash_algo];
 247                 free(hash_name);
 248         } else {
 249                 reader->hash_algo = &hash_algos[GIT_HASH_SHA1];
 250         }
 251 }
 252
 253 static int process_dummy_ref(const struct packet_reader *reader)
 254 {
 255         const char *line = reader->line;
 256         struct object_id oid;
 257         const char *name;
 258
 259         if (parse_oid_hex_algop(line, &oid, &name, reader->hash_algo))
 260                 return 0;
 261         if (*name != ' ')
 262                 return 0;
 263         name++;
 264
 265         return oideq(null_oid(), &oid) && !strcmp(name, "capabilities^{}");
 266 }
 267
 268 static void check_no_capabilities(const char *line, int len)
 269 {
 270         if (strlen(line) != len)
 271                 warning(_("ignoring capabilities after first line '%s'"),
 272                         line + strlen(line));
 273 }
 274
 275 static int process_ref(const struct packet_reader *reader, int len,
 276                        struct ref ***list, unsigned int flags,
 277                        struct oid_array *extra_have)
 278 {
 279         const char *line = reader->line;
 280         struct object_id old_oid;
 281         const char *name;
 282
 283         if (parse_oid_hex_algop(line, &old_oid, &name, reader->hash_algo))
 284                 return 0;
 285         if (*name != ' ')
 286                 return 0;
 287         name++;
 288
 289         if (extra_have && !strcmp(name, ".have")) {
 290                 oid_array_append(extra_have, &old_oid);
 291         } else if (!strcmp(name, "capabilities^{}")) {
 292                 die(_("protocol error: unexpected capabilities^{}"));
 293         } else if (check_ref(name, flags)) {
 294                 struct ref *ref = alloc_ref(name);
 295                 oidcpy(&ref->old_oid, &old_oid);
 296                 **list = ref;
 297                 *list = &ref->next;
 298         }
 299         check_no_capabilities(line, len);
 300         return 1;
 301 }
 302
 303 static int process_shallow(const struct packet_reader *reader, int len,
 304                            struct oid_array *shallow_points)
 305 {
 306         const char *line = reader->line;
 307         const char *arg;
 308         struct object_id old_oid;
 309
 310         if (!skip_prefix(line, "shallow ", &arg))
 311                 return 0;
 312
 313         if (get_oid_hex_algop(arg, &old_oid, reader->hash_algo))
 314                 die(_("protocol error: expected shallow sha-1, got '%s'"), arg);
 315         if (!shallow_points)
 316                 die(_("repository on the other end cannot be shallow"));
 317         oid_array_append(shallow_points, &old_oid);
 318         check_no_capabilities(line, len);
 319         return 1;
 320 }
 321
 322 enum get_remote_heads_state {
 323         EXPECTING_FIRST_REF = 0,
 324         EXPECTING_REF,
 325         EXPECTING_SHALLOW,
 326         EXPECTING_DONE,
 327 };
 328
 329 /*
 330  * Read all the refs from the other end
 331  */
 332 struct ref **get_remote_heads(struct packet_reader *reader,
 333                               struct ref **list, unsigned int flags,
 334                               struct oid_array *extra_have,
 335                               struct oid_array *shallow_points)
 336 {
 337         struct ref **orig_list = list;
 338         int len = 0;
 339         enum get_remote_heads_state state = EXPECTING_FIRST_REF;
 340
 341         *list = NULL;
 342
 343         while (state != EXPECTING_DONE) {
 344                 switch (packet_reader_read(reader)) {
 345                 case PACKET_READ_EOF:
 346                         die_initial_contact(1);
 347                 case PACKET_READ_NORMAL:
 348                         len = reader->pktlen;
 349                         break;
 350                 case PACKET_READ_FLUSH:
 351                         state = EXPECTING_DONE;
 352                         break;
 353                 case PACKET_READ_DELIM:
 354                 case PACKET_READ_RESPONSE_END:
 355                         die(_("invalid packet"));
 356                 }
 357
 358                 switch (state) {
 359                 case EXPECTING_FIRST_REF:
 360                         process_capabilities(reader, &len);
 361                         if (process_dummy_ref(reader)) {
 362                                 state = EXPECTING_SHALLOW;
 363                                 break;
 364                         }
 365                         state = EXPECTING_REF;
 366                         /* fallthrough */
 367                 case EXPECTING_REF:
 368                         if (process_ref(reader, len, &list, flags, extra_have))
 369                                 break;
 370                         state = EXPECTING_SHALLOW;
 371                         /* fallthrough */
 372                 case EXPECTING_SHALLOW:
 373                         if (process_shallow(reader, len, shallow_points))
 374                                 break;
 375                         die(_("protocol error: unexpected '%s'"), reader->line);
 376                 case EXPECTING_DONE:
 377                         break;
 378                 }
 379         }
 380
 381         annotate_refs_with_symref_info(*orig_list);
 382
 383         return list;
 384 }
 385
 386 /* Returns 1 when a valid ref has been added to `list`, 0 otherwise */
 387 static int process_ref_v2(struct packet_reader *reader, struct ref ***list,
 388                           const char **unborn_head_target)
 389 {
 390         int ret = 1;
 391         int i = 0;
 392         struct object_id old_oid;
 393         struct ref *ref;
 394         struct string_list line_sections = STRING_LIST_INIT_DUP;
 395         const char *end;
 396         const char *line = reader->line;
 397
 398         /*
 399          * Ref lines have a number of fields which are space deliminated.  The
 400          * first field is the OID of the ref.  The second field is the ref
 401          * name.  Subsequent fields (symref-target and peeled) are optional and
 402          * don't have a particular order.
 403          */
 404         if (string_list_split(&line_sections, line, ' ', -1) < 2) {
 405                 ret = 0;
 406                 goto out;
 407         }
 408
 409         if (!strcmp("unborn", line_sections.items[i].string)) {
 410                 i++;
 411                 if (unborn_head_target &&
 412                     !strcmp("HEAD", line_sections.items[i++].string)) {
 413                         /*
 414                          * Look for the symref target (if any). If found,
 415                          * return it to the caller.
 416                          */
 417                         for (; i < line_sections.nr; i++) {
 418                                 const char *arg = line_sections.items[i].string;
 419
 420                                 if (skip_prefix(arg, "symref-target:", &arg)) {
 421                                         *unborn_head_target = xstrdup(arg);
 422                                         break;
 423                                 }
 424                         }
 425                 }
 426                 goto out;
 427         }
 428         if (parse_oid_hex_algop(line_sections.items[i++].string, &old_oid, &end, reader->hash_algo) ||
 429             *end) {
 430                 ret = 0;
 431                 goto out;
 432         }
 433
 434         ref = alloc_ref(line_sections.items[i++].string);
 435
 436         memcpy(ref->old_oid.hash, old_oid.hash, reader->hash_algo->rawsz);
 437         **list = ref;
 438         *list = &ref->next;
 439
 440         for (; i < line_sections.nr; i++) {
 441                 const char *arg = line_sections.items[i].string;
 442                 if (skip_prefix(arg, "symref-target:", &arg))
 443                         ref->symref = xstrdup(arg);
 444
 445                 if (skip_prefix(arg, "peeled:", &arg)) {
 446                         struct object_id peeled_oid;
 447                         char *peeled_name;
 448                         struct ref *peeled;
 449                         if (parse_oid_hex_algop(arg, &peeled_oid, &end,
 450                                                 reader->hash_algo) || *end) {
 451                                 ret = 0;
 452                                 goto out;
 453                         }
 454
 455                         peeled_name = xstrfmt("%s^{}", ref->name);
 456                         peeled = alloc_ref(peeled_name);
 457
 458                         memcpy(peeled->old_oid.hash, peeled_oid.hash,
 459                                reader->hash_algo->rawsz);
 460                         **list = peeled;
 461                         *list = &peeled->next;
 462
 463                         free(peeled_name);
 464                 }
 465         }
 466
 467 out:
 468         string_list_clear(&line_sections, 0);
 469         return ret;
 470 }
 471
 472 void check_stateless_delimiter(int stateless_rpc,
 473                               struct packet_reader *reader,
 474                               const char *error)
 475 {
 476         if (!stateless_rpc)
 477                 return; /* not in stateless mode, no delimiter expected */
 478         if (packet_reader_read(reader) != PACKET_READ_RESPONSE_END)
 479                 die("%s", error);
 480 }
 481
 482 static void send_capabilities(int fd_out, struct packet_reader *reader)
 483 {
 484         const char *hash_name;
 485
 486         if (server_supports_v2("agent"))
 487                 packet_write_fmt(fd_out, "agent=%s", git_user_agent_sanitized());
 488
 489         if (server_feature_v2("object-format", &hash_name)) {
 490                 int hash_algo = hash_algo_by_name(hash_name);
 491                 if (hash_algo == GIT_HASH_UNKNOWN)
 492                         die(_("unknown object format '%s' specified by server"), hash_name);
 493                 reader->hash_algo = &hash_algos[hash_algo];
 494                 packet_write_fmt(fd_out, "object-format=%s", reader->hash_algo->name);
 495         } else {
 496                 reader->hash_algo = &hash_algos[GIT_HASH_SHA1];
 497         }
 498 }
 499
 500 int get_remote_bundle_uri(int fd_out, struct packet_reader *reader,
 501                           struct bundle_list *bundles, int stateless_rpc)
 502 {
 503         int line_nr = 1;
 504
 505         /* Assert bundle-uri support */
 506         ensure_server_supports_v2("bundle-uri");
 507
 508         /* (Re-)send capabilities */
 509         send_capabilities(fd_out, reader);
 510
 511         /* Send command */
 512         packet_write_fmt(fd_out, "command=bundle-uri\n");
 513         packet_delim(fd_out);
 514
 515         packet_flush(fd_out);
 516
 517         /* Process response from server */
 518         while (packet_reader_read(reader) == PACKET_READ_NORMAL) {
 519                 const char *line = reader->line;
 520                 line_nr++;
 521
 522                 if (!bundle_uri_parse_line(bundles, line))
 523                         continue;
 524
 525                 return error(_("error on bundle-uri response line %d: %s"),
 526                              line_nr, line);
 527         }
 528
 529         if (reader->status != PACKET_READ_FLUSH)
 530                 return error(_("expected flush after bundle-uri listing"));
 531
 532         /*
 533          * Might die(), but obscure enough that that's OK, e.g. in
 534          * serve.c we'll call BUG() on its equivalent (the
 535          * PACKET_READ_RESPONSE_END check).
 536          */
 537         check_stateless_delimiter(stateless_rpc, reader,
 538                                   _("expected response end packet after ref listing"));
 539
 540         return 0;
 541 }
 542
 543 struct ref **get_remote_refs(int fd_out, struct packet_reader *reader,
 544                              struct ref **list, int for_push,
 545                              struct transport_ls_refs_options *transport_options,
 546                              const struct string_list *server_options,
 547                              int stateless_rpc)
 548 {
 549         int i;
 550         struct strvec *ref_prefixes = transport_options ?
 551                 &transport_options->ref_prefixes : NULL;
 552         const char **unborn_head_target = transport_options ?
 553                 &transport_options->unborn_head_target : NULL;
 554         *list = NULL;
 555
 556         ensure_server_supports_v2("ls-refs");
 557         packet_write_fmt(fd_out, "command=ls-refs\n");
 558
 559         /* Send capabilities */
 560         send_capabilities(fd_out, reader);
 561
 562         if (server_options && server_options->nr) {
 563                 ensure_server_supports_v2("server-option");
 564                 for (i = 0; i < server_options->nr; i++)
 565                         packet_write_fmt(fd_out, "server-option=%s",
 566                                          server_options->items[i].string);
 567         }
 568
 569         packet_delim(fd_out);
 570         /* When pushing we don't want to request the peeled tags */
 571         if (!for_push)
 572                 packet_write_fmt(fd_out, "peel\n");
 573         packet_write_fmt(fd_out, "symrefs\n");
 574         if (server_supports_feature("ls-refs", "unborn", 0))
 575                 packet_write_fmt(fd_out, "unborn\n");
 576         for (i = 0; ref_prefixes && i < ref_prefixes->nr; i++) {
 577                 packet_write_fmt(fd_out, "ref-prefix %s\n",
 578                                  ref_prefixes->v[i]);
 579         }
 580         packet_flush(fd_out);
 581
 582         /* Process response from server */
 583         while (packet_reader_read(reader) == PACKET_READ_NORMAL) {
 584                 if (!process_ref_v2(reader, &list, unborn_head_target))
 585                         die(_("invalid ls-refs response: %s"), reader->line);
 586         }
 587
 588         if (reader->status != PACKET_READ_FLUSH)
 589                 die(_("expected flush after ref listing"));
 590
 591         check_stateless_delimiter(stateless_rpc, reader,
 592                                   _("expected response end packet after ref listing"));
 593
 594         return list;
 595 }
 596
 597 const char *parse_feature_value(const char *feature_list, const char *feature, int *lenp, int *offset)
 598 {
 599         int len;
 600
 601         if (!feature_list)
 602                 return NULL;
 603
 604         len = strlen(feature);
 605         if (offset)
 606                 feature_list += *offset;
 607         while (*feature_list) {
 608                 const char *found = strstr(feature_list, feature);
 609                 if (!found)
 610                         return NULL;
 611                 if (feature_list == found || isspace(found[-1])) {
 612                         const char *value = found + len;
 613                         /* feature with no value (e.g., "thin-pack") */
 614                         if (!*value || isspace(*value)) {
 615                                 if (lenp)
 616                                         *lenp = 0;
 617                                 if (offset)
 618                                         *offset = found + len - feature_list;
 619                                 return value;
 620                         }
 621                         /* feature with a value (e.g., "agent=git/1.2.3") */
 622                         else if (*value == '=') {
 623                                 int end;
 624
 625                                 value++;
 626                                 end = strcspn(value, " \t\n");
 627                                 if (lenp)
 628                                         *lenp = end;
 629                                 if (offset)
 630                                         *offset = value + end - feature_list;
 631                                 return value;
 632                         }
 633                         /*
 634                          * otherwise we matched a substring of another feature;
 635                          * keep looking
 636                          */
 637                 }
 638                 feature_list = found + 1;
 639         }
 640         return NULL;
 641 }
 642
 643 int server_supports_hash(const char *desired, int *feature_supported)
 644 {
 645         int offset = 0;
 646         int len;
 647         const char *hash;
 648
 649         hash = next_server_feature_value("object-format", &len, &offset);
 650         if (feature_supported)
 651                 *feature_supported = !!hash;
 652         if (!hash) {
 653                 hash = hash_algos[GIT_HASH_SHA1].name;
 654                 len = strlen(hash);
 655         }
 656         while (hash) {
 657                 if (!xstrncmpz(desired, hash, len))
 658                         return 1;
 659
 660                 hash = next_server_feature_value("object-format", &len, &offset);
 661         }
 662         return 0;
 663 }
 664
 665 int parse_feature_request(const char *feature_list, const char *feature)
 666 {
 667         return !!parse_feature_value(feature_list, feature, NULL, NULL);
 668 }
 669
 670 static const char *next_server_feature_value(const char *feature, int *len, int *offset)
 671 {
 672         return parse_feature_value(server_capabilities_v1, feature, len, offset);
 673 }
 674
 675 const char *server_feature_value(const char *feature, int *len)
 676 {
 677         return parse_feature_value(server_capabilities_v1, feature, len, NULL);
 678 }
 679
 680 int server_supports(const char *feature)
 681 {
 682         return !!server_feature_value(feature, NULL);
 683 }
 684
 685 enum protocol {
 686         PROTO_LOCAL = 1,
 687         PROTO_FILE,
 688         PROTO_SSH,
 689         PROTO_GIT
 690 };
 691
 692 int url_is_local_not_ssh(const char *url)
 693 {
 694         const char *colon = strchr(url, ':');
 695         const char *slash = strchr(url, '/');
 696         return !colon || (slash && slash < colon) ||
 697                 (has_dos_drive_prefix(url) && is_valid_path(url));
 698 }
 699
 700 static const char *prot_name(enum protocol protocol)
 701 {
 702         switch (protocol) {
 703                 case PROTO_LOCAL:
 704                 case PROTO_FILE:
 705                         return "file";
 706                 case PROTO_SSH:
 707                         return "ssh";
 708                 case PROTO_GIT:
 709                         return "git";
 710                 default:
 711                         return "unknown protocol";
 712         }
 713 }
 714
 715 static enum protocol get_protocol(const char *name)
 716 {
 717         if (!strcmp(name, "ssh"))
 718                 return PROTO_SSH;
 719         if (!strcmp(name, "git"))
 720                 return PROTO_GIT;
 721         if (!strcmp(name, "git+ssh")) /* deprecated - do not use */
 722                 return PROTO_SSH;
 723         if (!strcmp(name, "ssh+git")) /* deprecated - do not use */
 724                 return PROTO_SSH;
 725         if (!strcmp(name, "file"))
 726                 return PROTO_FILE;
 727         die(_("protocol '%s' is not supported"), name);
 728 }
 729
 730 static char *host_end(char **hoststart, int removebrackets)
 731 {
 732         char *host = *hoststart;
 733         char *end;
 734         char *start = strstr(host, "@[");
 735         if (start)
 736                 start++; /* Jump over '@' */
 737         else
 738                 start = host;
 739         if (start[0] == '[') {
 740                 end = strchr(start + 1, ']');
 741                 if (end) {
 742                         if (removebrackets) {
 743                                 *end = 0;
 744                                 memmove(start, start + 1, end - start);
 745                                 end++;
 746                         }
 747                 } else
 748                         end = host;
 749         } else
 750                 end = host;
 751         return end;
 752 }
 753
 754 #define STR_(s) # s
 755 #define STR(s)  STR_(s)
 756
 757 static void get_host_and_port(char **host, const char **port)
 758 {
 759         char *colon, *end;
 760         end = host_end(host, 1);
 761         colon = strchr(end, ':');
 762         if (colon) {
 763                 long portnr = strtol(colon + 1, &end, 10);
 764                 if (end != colon + 1 && *end == '\0' && 0 <= portnr && portnr < 65536) {
 765                         *colon = 0;
 766                         *port = colon + 1;
 767                 } else if (!colon[1]) {
 768                         *colon = 0;
 769                 }
 770         }
 771 }
 772
 773 static void enable_keepalive(int sockfd)
 774 {
 775         int ka = 1;
 776
 777         if (setsockopt(sockfd, SOL_SOCKET, SO_KEEPALIVE, &ka, sizeof(ka)) < 0)
 778                 error_errno(_("unable to set SO_KEEPALIVE on socket"));
 779 }
 780
 781 #ifndef NO_IPV6
 782
 783 static const char *ai_name(const struct addrinfo *ai)
 784 {
 785         static char addr[NI_MAXHOST];
 786         if (getnameinfo(ai->ai_addr, ai->ai_addrlen, addr, sizeof(addr), NULL, 0,
 787                         NI_NUMERICHOST) != 0)
 788                 xsnprintf(addr, sizeof(addr), "(unknown)");
 789
 790         return addr;
 791 }
 792
 793 /*
 794  * Returns a connected socket() fd, or else die()s.
 795  */
 796 static int git_tcp_connect_sock(char *host, int flags)
 797 {
 798         struct strbuf error_message = STRBUF_INIT;
 799         int sockfd = -1;
 800         const char *port = STR(DEFAULT_GIT_PORT);
 801         struct addrinfo hints, *ai0, *ai;
 802         int gai;
 803         int cnt = 0;
 804
 805         get_host_and_port(&host, &port);
 806         if (!*port)
 807                 port = "<none>";
 808
 809         memset(&hints, 0, sizeof(hints));
 810         if (flags & CONNECT_IPV4)
 811                 hints.ai_family = AF_INET;
 812         else if (flags & CONNECT_IPV6)
 813                 hints.ai_family = AF_INET6;
 814         hints.ai_socktype = SOCK_STREAM;
 815         hints.ai_protocol = IPPROTO_TCP;
 816
 817         if (flags & CONNECT_VERBOSE)
 818                 fprintf(stderr, _("Looking up %s ... "), host);
 819
 820         gai = getaddrinfo(host, port, &hints, &ai);
 821         if (gai)
 822                 die(_("unable to look up %s (port %s) (%s)"), host, port, gai_strerror(gai));
 823
 824         if (flags & CONNECT_VERBOSE)
 825                 /* TRANSLATORS: this is the end of "Looking up %s ... " */
 826                 fprintf(stderr, _("done.\nConnecting to %s (port %s) ... "), host, port);
 827
 828         for (ai0 = ai; ai; ai = ai->ai_next, cnt++) {
 829                 sockfd = socket(ai->ai_family,
 830                                 ai->ai_socktype, ai->ai_protocol);
 831                 if ((sockfd < 0) ||
 832                     (connect(sockfd, ai->ai_addr, ai->ai_addrlen) < 0)) {
 833                         strbuf_addf(&error_message, "%s[%d: %s]: errno=%s\n",
 834                                     host, cnt, ai_name(ai), strerror(errno));
 835                         if (0 <= sockfd)
 836                                 close(sockfd);
 837                         sockfd = -1;
 838                         continue;
 839                 }
 840                 if (flags & CONNECT_VERBOSE)
 841                         fprintf(stderr, "%s ", ai_name(ai));
 842                 break;
 843         }
 844
 845         freeaddrinfo(ai0);
 846
 847         if (sockfd < 0)
 848                 die(_("unable to connect to %s:\n%s"), host, error_message.buf);
 849
 850         enable_keepalive(sockfd);
 851
 852         if (flags & CONNECT_VERBOSE)
 853                 /* TRANSLATORS: this is the end of "Connecting to %s (port %s) ... " */
 854                 fprintf_ln(stderr, _("done."));
 855
 856         strbuf_release(&error_message);
 857
 858         return sockfd;
 859 }
 860
 861 #else /* NO_IPV6 */
 862
 863 /*
 864  * Returns a connected socket() fd, or else die()s.
 865  */
 866 static int git_tcp_connect_sock(char *host, int flags)
 867 {
 868         struct strbuf error_message = STRBUF_INIT;
 869         int sockfd = -1;
 870         const char *port = STR(DEFAULT_GIT_PORT);
 871         char *ep;
 872         struct hostent *he;
 873         struct sockaddr_in sa;
 874         char **ap;
 875         unsigned int nport;
 876         int cnt;
 877
 878         get_host_and_port(&host, &port);
 879
 880         if (flags & CONNECT_VERBOSE)
 881                 fprintf(stderr, _("Looking up %s ... "), host);
 882
 883         he = gethostbyname(host);
 884         if (!he)
 885                 die(_("unable to look up %s (%s)"), host, hstrerror(h_errno));
 886         nport = strtoul(port, &ep, 10);
 887         if ( ep == port || *ep ) {
 888                 /* Not numeric */
 889                 struct servent *se = getservbyname(port,"tcp");
 890                 if ( !se )
 891                         die(_("unknown port %s"), port);
 892                 nport = se->s_port;
 893         }
 894
 895         if (flags & CONNECT_VERBOSE)
 896                 /* TRANSLATORS: this is the end of "Looking up %s ... " */
 897                 fprintf(stderr, _("done.\nConnecting to %s (port %s) ... "), host, port);
 898
 899         for (cnt = 0, ap = he->h_addr_list; *ap; ap++, cnt++) {
 900                 memset(&sa, 0, sizeof sa);
 901                 sa.sin_family = he->h_addrtype;
 902                 sa.sin_port = htons(nport);
 903                 memcpy(&sa.sin_addr, *ap, he->h_length);
 904
 905                 sockfd = socket(he->h_addrtype, SOCK_STREAM, 0);
 906                 if ((sockfd < 0) ||
 907                     connect(sockfd, (struct sockaddr *)&sa, sizeof sa) < 0) {
 908                         strbuf_addf(&error_message, "%s[%d: %s]: errno=%s\n",
 909                                 host,
 910                                 cnt,
 911                                 inet_ntoa(*(struct in_addr *)&sa.sin_addr),
 912                                 strerror(errno));
 913                         if (0 <= sockfd)
 914                                 close(sockfd);
 915                         sockfd = -1;
 916                         continue;
 917                 }
 918                 if (flags & CONNECT_VERBOSE)
 919                         fprintf(stderr, "%s ",
 920                                 inet_ntoa(*(struct in_addr *)&sa.sin_addr));
 921                 break;
 922         }
 923
 924         if (sockfd < 0)
 925                 die(_("unable to connect to %s:\n%s"), host, error_message.buf);
 926
 927         enable_keepalive(sockfd);
 928
 929         if (flags & CONNECT_VERBOSE)
 930                 /* TRANSLATORS: this is the end of "Connecting to %s (port %s) ... " */
 931                 fprintf_ln(stderr, _("done."));
 932
 933         return sockfd;
 934 }
 935
 936 #endif /* NO_IPV6 */
 937
 938
 939 /*
 940  * Dummy child_process returned by git_connect() if the transport protocol
 941  * does not need fork(2).
 942  */
 943 static struct child_process no_fork = CHILD_PROCESS_INIT;
 944
 945 int git_connection_is_socket(struct child_process *conn)
 946 {
 947         return conn == &no_fork;
 948 }
 949
 950 static struct child_process *git_tcp_connect(int fd[2], char *host, int flags)
 951 {
 952         int sockfd = git_tcp_connect_sock(host, flags);
 953
 954         fd[0] = sockfd;
 955         fd[1] = dup(sockfd);
 956
 957         return &no_fork;
 958 }
 959
 960
 961 static char *git_proxy_command;
 962
 963 static int git_proxy_command_options(const char *var, const char *value,
 964                 void *cb)
 965 {
 966         if (!strcmp(var, "core.gitproxy")) {
 967                 const char *for_pos;
 968                 int matchlen = -1;
 969                 int hostlen;
 970                 const char *rhost_name = cb;
 971                 int rhost_len = strlen(rhost_name);
 972
 973                 if (git_proxy_command)
 974                         return 0;
 975                 if (!value)
 976                         return config_error_nonbool(var);
 977                 /* [core]
 978                  * ;# matches www.kernel.org as well
 979                  * gitproxy = netcatter-1 for kernel.org
 980                  * gitproxy = netcatter-2 for sample.xz
 981                  * gitproxy = netcatter-default
 982                  */
 983                 for_pos = strstr(value, " for ");
 984                 if (!for_pos)
 985                         /* matches everybody */
 986                         matchlen = strlen(value);
 987                 else {
 988                         hostlen = strlen(for_pos + 5);
 989                         if (rhost_len < hostlen)
 990                                 matchlen = -1;
 991                         else if (!strncmp(for_pos + 5,
 992                                           rhost_name + rhost_len - hostlen,
 993                                           hostlen) &&
 994                                  ((rhost_len == hostlen) ||
 995                                   rhost_name[rhost_len - hostlen -1] == '.'))
 996                                 matchlen = for_pos - value;
 997                         else
 998                                 matchlen = -1;
 999                 }
1000                 if (0 <= matchlen) {
1001                         /* core.gitproxy = none for kernel.org */
1002                         if (matchlen == 4 &&
1003                             !memcmp(value, "none", 4))
1004                                 matchlen = 0;
1005                         git_proxy_command = xmemdupz(value, matchlen);
1006                 }
1007                 return 0;
1008         }
1009
1010         return git_default_config(var, value, cb);
1011 }
1012
1013 static int git_use_proxy(const char *host)
1014 {
1015         git_proxy_command = getenv("GIT_PROXY_COMMAND");
1016         git_config(git_proxy_command_options, (void*)host);
1017         return (git_proxy_command && *git_proxy_command);
1018 }
1019
1020 static struct child_process *git_proxy_connect(int fd[2], char *host)
1021 {
1022         const char *port = STR(DEFAULT_GIT_PORT);
1023         struct child_process *proxy;
1024
1025         get_host_and_port(&host, &port);
1026
1027         if (looks_like_command_line_option(host))
1028                 die(_("strange hostname '%s' blocked"), host);
1029         if (looks_like_command_line_option(port))
1030                 die(_("strange port '%s' blocked"), port);
1031
1032         proxy = xmalloc(sizeof(*proxy));
1033         child_process_init(proxy);
1034         strvec_push(&proxy->args, git_proxy_command);
1035         strvec_push(&proxy->args, host);
1036         strvec_push(&proxy->args, port);
1037         proxy->in = -1;
1038         proxy->out = -1;
1039         if (start_command(proxy))
1040                 die(_("cannot start proxy %s"), git_proxy_command);
1041         fd[0] = proxy->out; /* read from proxy stdout */
1042         fd[1] = proxy->in;  /* write to proxy stdin */
1043         return proxy;
1044 }
1045
1046 static char *get_port(char *host)
1047 {
1048         char *end;
1049         char *p = strchr(host, ':');
1050
1051         if (p) {
1052                 long port = strtol(p + 1, &end, 10);
1053                 if (end != p + 1 && *end == '\0' && 0 <= port && port < 65536) {
1054                         *p = '\0';
1055                         return p+1;
1056                 }
1057         }
1058
1059         return NULL;
1060 }
1061
1062 /*
1063  * Extract protocol and relevant parts from the specified connection URL.
1064  * The caller must free() the returned strings.
1065  */
1066 static enum protocol parse_connect_url(const char *url_orig, char **ret_host,
1067                                        char **ret_path)
1068 {
1069         char *url;
1070         char *host, *path;
1071         char *end;
1072         int separator = '/';
1073         enum protocol protocol = PROTO_LOCAL;
1074
1075         if (is_url(url_orig))
1076                 url = url_decode(url_orig);
1077         else
1078                 url = xstrdup(url_orig);
1079
1080         host = strstr(url, "://");
1081         if (host) {
1082                 *host = '\0';
1083                 protocol = get_protocol(url);
1084                 host += 3;
1085         } else {
1086                 host = url;
1087                 if (!url_is_local_not_ssh(url)) {
1088                         protocol = PROTO_SSH;
1089                         separator = ':';
1090                 }
1091         }
1092
1093         /*
1094          * Don't do destructive transforms as protocol code does
1095          * '[]' unwrapping in get_host_and_port()
1096          */
1097         end = host_end(&host, 0);
1098
1099         if (protocol == PROTO_LOCAL)
1100                 path = end;
1101         else if (protocol == PROTO_FILE && *host != '/' &&
1102                  !has_dos_drive_prefix(host) &&
1103                  offset_1st_component(host - 2) > 1)
1104                 path = host - 2; /* include the leading "//" */
1105         else if (protocol == PROTO_FILE && has_dos_drive_prefix(end))
1106                 path = end; /* "file://$(pwd)" may be "file://C:/projects/repo" */
1107         else
1108                 path = strchr(end, separator);
1109
1110         if (!path || !*path)
1111                 die(_("no path specified; see 'git help pull' for valid url syntax"));
1112
1113         /*
1114          * null-terminate hostname and point path to ~ for URL's like this:
1115          *    ssh://host.xz/~user/repo
1116          */
1117
1118         end = path; /* Need to \0 terminate host here */
1119         if (separator == ':')
1120                 path++; /* path starts after ':' */
1121         if (protocol == PROTO_GIT || protocol == PROTO_SSH) {
1122                 if (path[1] == '~')
1123                         path++;
1124         }
1125
1126         path = xstrdup(path);
1127         *end = '\0';
1128
1129         *ret_host = xstrdup(host);
1130         *ret_path = path;
1131         free(url);
1132         return protocol;
1133 }
1134
1135 static const char *get_ssh_command(void)
1136 {
1137         const char *ssh;
1138
1139         if ((ssh = getenv("GIT_SSH_COMMAND")))
1140                 return ssh;
1141
1142         if (!git_config_get_string_tmp("core.sshcommand", &ssh))
1143                 return ssh;
1144
1145         return NULL;
1146 }
1147
1148 enum ssh_variant {
1149         VARIANT_AUTO,
1150         VARIANT_SIMPLE,
1151         VARIANT_SSH,
1152         VARIANT_PLINK,
1153         VARIANT_PUTTY,
1154         VARIANT_TORTOISEPLINK,
1155 };
1156
1157 static void override_ssh_variant(enum ssh_variant *ssh_variant)
1158 {
1159         const char *variant = getenv("GIT_SSH_VARIANT");
1160
1161         if (!variant && git_config_get_string_tmp("ssh.variant", &variant))
1162                 return;
1163
1164         if (!strcmp(variant, "auto"))
1165                 *ssh_variant = VARIANT_AUTO;
1166         else if (!strcmp(variant, "plink"))
1167                 *ssh_variant = VARIANT_PLINK;
1168         else if (!strcmp(variant, "putty"))
1169                 *ssh_variant = VARIANT_PUTTY;
1170         else if (!strcmp(variant, "tortoiseplink"))
1171                 *ssh_variant = VARIANT_TORTOISEPLINK;
1172         else if (!strcmp(variant, "simple"))
1173                 *ssh_variant = VARIANT_SIMPLE;
1174         else
1175                 *ssh_variant = VARIANT_SSH;
1176 }
1177
1178 static enum ssh_variant determine_ssh_variant(const char *ssh_command,
1179                                               int is_cmdline)
1180 {
1181         enum ssh_variant ssh_variant = VARIANT_AUTO;
1182         const char *variant;
1183         char *p = NULL;
1184
1185         override_ssh_variant(&ssh_variant);
1186
1187         if (ssh_variant != VARIANT_AUTO)
1188                 return ssh_variant;
1189
1190         if (!is_cmdline) {
1191                 p = xstrdup(ssh_command);
1192                 variant = basename(p);
1193         } else {
1194                 const char **ssh_argv;
1195
1196                 p = xstrdup(ssh_command);
1197                 if (split_cmdline(p, &ssh_argv) > 0) {
1198                         variant = basename((char *)ssh_argv[0]);
1199                         /*
1200                          * At this point, variant points into the buffer
1201                          * referenced by p, hence we do not need ssh_argv
1202                          * any longer.
1203                          */
1204                         free(ssh_argv);
1205                 } else {
1206                         free(p);
1207                         return ssh_variant;
1208                 }
1209         }
1210
1211         if (!strcasecmp(variant, "ssh") ||
1212             !strcasecmp(variant, "ssh.exe"))
1213                 ssh_variant = VARIANT_SSH;
1214         else if (!strcasecmp(variant, "plink") ||
1215                  !strcasecmp(variant, "plink.exe"))
1216                 ssh_variant = VARIANT_PLINK;
1217         else if (!strcasecmp(variant, "tortoiseplink") ||
1218                  !strcasecmp(variant, "tortoiseplink.exe"))
1219                 ssh_variant = VARIANT_TORTOISEPLINK;
1220
1221         free(p);
1222         return ssh_variant;
1223 }
1224
1225 /*
1226  * Open a connection using Git's native protocol.
1227  *
1228  * The caller is responsible for freeing hostandport, but this function may
1229  * modify it (for example, to truncate it to remove the port part).
1230  */
1231 static struct child_process *git_connect_git(int fd[2], char *hostandport,
1232                                              const char *path, const char *prog,
1233                                              enum protocol_version version,
1234                                              int flags)
1235 {
1236         struct child_process *conn;
1237         struct strbuf request = STRBUF_INIT;
1238         /*
1239          * Set up virtual host information based on where we will
1240          * connect, unless the user has overridden us in
1241          * the environment.
1242          */
1243         char *target_host = getenv("GIT_OVERRIDE_VIRTUAL_HOST");
1244         if (target_host)
1245                 target_host = xstrdup(target_host);
1246         else
1247                 target_host = xstrdup(hostandport);
1248
1249         transport_check_allowed("git");
1250         if (strchr(target_host, '\n') || strchr(path, '\n'))
1251                 die(_("newline is forbidden in git:// hosts and repo paths"));
1252
1253         /*
1254          * These underlying connection commands die() if they
1255          * cannot connect.
1256          */
1257         if (git_use_proxy(hostandport))
1258                 conn = git_proxy_connect(fd, hostandport);
1259         else
1260                 conn = git_tcp_connect(fd, hostandport, flags);
1261         /*
1262          * Separate original protocol components prog and path
1263          * from extended host header with a NUL byte.
1264          *
1265          * Note: Do not add any other headers here!  Doing so
1266          * will cause older git-daemon servers to crash.
1267          */
1268         strbuf_addf(&request,
1269                     "%s %s%chost=%s%c",
1270                     prog, path, 0,
1271                     target_host, 0);
1272
1273         /* If using a new version put that stuff here after a second null byte */
1274         if (version > 0) {
1275                 strbuf_addch(&request, '\0');
1276                 strbuf_addf(&request, "version=%d%c",
1277                             version, '\0');
1278         }
1279
1280         packet_write(fd[1], request.buf, request.len);
1281
1282         free(target_host);
1283         strbuf_release(&request);
1284         return conn;
1285 }
1286
1287 /*
1288  * Append the appropriate environment variables to `env` and options to
1289  * `args` for running ssh in Git's SSH-tunneled transport.
1290  */
1291 static void push_ssh_options(struct strvec *args, struct strvec *env,
1292                              enum ssh_variant variant, const char *port,
1293                              enum protocol_version version, int flags)
1294 {
1295         if (variant == VARIANT_SSH &&
1296             version > 0) {
1297                 strvec_push(args, "-o");
1298                 strvec_push(args, "SendEnv=" GIT_PROTOCOL_ENVIRONMENT);
1299                 strvec_pushf(env, GIT_PROTOCOL_ENVIRONMENT "=version=%d",
1300                              version);
1301         }
1302
1303         if (flags & CONNECT_IPV4) {
1304                 switch (variant) {
1305                 case VARIANT_AUTO:
1306                         BUG("VARIANT_AUTO passed to push_ssh_options");
1307                 case VARIANT_SIMPLE:
1308                         die(_("ssh variant 'simple' does not support -4"));
1309                 case VARIANT_SSH:
1310                 case VARIANT_PLINK:
1311                 case VARIANT_PUTTY:
1312                 case VARIANT_TORTOISEPLINK:
1313                         strvec_push(args, "-4");
1314                 }
1315         } else if (flags & CONNECT_IPV6) {
1316                 switch (variant) {
1317                 case VARIANT_AUTO:
1318                         BUG("VARIANT_AUTO passed to push_ssh_options");
1319                 case VARIANT_SIMPLE:
1320                         die(_("ssh variant 'simple' does not support -6"));
1321                 case VARIANT_SSH:
1322                 case VARIANT_PLINK:
1323                 case VARIANT_PUTTY:
1324                 case VARIANT_TORTOISEPLINK:
1325                         strvec_push(args, "-6");
1326                 }
1327         }
1328
1329         if (variant == VARIANT_TORTOISEPLINK)
1330                 strvec_push(args, "-batch");
1331
1332         if (port) {
1333                 switch (variant) {
1334                 case VARIANT_AUTO:
1335                         BUG("VARIANT_AUTO passed to push_ssh_options");
1336                 case VARIANT_SIMPLE:
1337                         die(_("ssh variant 'simple' does not support setting port"));
1338                 case VARIANT_SSH:
1339                         strvec_push(args, "-p");
1340                         break;
1341                 case VARIANT_PLINK:
1342                 case VARIANT_PUTTY:
1343                 case VARIANT_TORTOISEPLINK:
1344                         strvec_push(args, "-P");
1345                 }
1346
1347                 strvec_push(args, port);
1348         }
1349 }
1350
1351 /* Prepare a child_process for use by Git's SSH-tunneled transport. */
1352 static void fill_ssh_args(struct child_process *conn, const char *ssh_host,
1353                           const char *port, enum protocol_version version,
1354                           int flags)
1355 {
1356         const char *ssh;
1357         enum ssh_variant variant;
1358
1359         if (looks_like_command_line_option(ssh_host))
1360                 die(_("strange hostname '%s' blocked"), ssh_host);
1361
1362         ssh = get_ssh_command();
1363         if (ssh) {
1364                 variant = determine_ssh_variant(ssh, 1);
1365         } else {
1366                 /*
1367                  * GIT_SSH is the no-shell version of
1368                  * GIT_SSH_COMMAND (and must remain so for
1369                  * historical compatibility).
1370                  */
1371                 conn->use_shell = 0;
1372
1373                 ssh = getenv("GIT_SSH");
1374                 if (!ssh)
1375                         ssh = "ssh";
1376                 variant = determine_ssh_variant(ssh, 0);
1377         }
1378
1379         if (variant == VARIANT_AUTO) {
1380                 struct child_process detect = CHILD_PROCESS_INIT;
1381
1382                 detect.use_shell = conn->use_shell;
1383                 detect.no_stdin = detect.no_stdout = detect.no_stderr = 1;
1384
1385                 strvec_push(&detect.args, ssh);
1386                 strvec_push(&detect.args, "-G");
1387                 push_ssh_options(&detect.args, &detect.env,
1388                                  VARIANT_SSH, port, version, flags);
1389                 strvec_push(&detect.args, ssh_host);
1390
1391                 variant = run_command(&detect) ? VARIANT_SIMPLE : VARIANT_SSH;
1392         }
1393
1394         strvec_push(&conn->args, ssh);
1395         push_ssh_options(&conn->args, &conn->env, variant, port, version,
1396                          flags);
1397         strvec_push(&conn->args, ssh_host);
1398 }
1399
1400 /*
1401  * This returns the dummy child_process `no_fork` if the transport protocol
1402  * does not need fork(2), or a struct child_process object if it does.  Once
1403  * done, finish the connection with finish_connect() with the value returned
1404  * from this function (it is safe to call finish_connect() with NULL to
1405  * support the former case).
1406  *
1407  * If it returns, the connect is successful; it just dies on errors (this
1408  * will hopefully be changed in a libification effort, to return NULL when
1409  * the connection failed).
1410  */
1411 struct child_process *git_connect(int fd[2], const char *url,
1412                                   const char *prog, int flags)
1413 {
1414         char *hostandport, *path;
1415         struct child_process *conn;
1416         enum protocol protocol;
1417         enum protocol_version version = get_protocol_version_config();
1418
1419         /*
1420          * NEEDSWORK: If we are trying to use protocol v2 and we are planning
1421          * to perform a push, then fallback to v0 since the client doesn't know
1422          * how to push yet using v2.
1423          */
1424         if (version == protocol_v2 && !strcmp("git-receive-pack", prog))
1425                 version = protocol_v0;
1426
1427         /* Without this we cannot rely on waitpid() to tell
1428          * what happened to our children.
1429          */
1430         signal(SIGCHLD, SIG_DFL);
1431
1432         protocol = parse_connect_url(url, &hostandport, &path);
1433         if ((flags & CONNECT_DIAG_URL) && (protocol != PROTO_SSH)) {
1434                 printf("Diag: url=%s\n", url ? url : "NULL");
1435                 printf("Diag: protocol=%s\n", prot_name(protocol));
1436                 printf("Diag: hostandport=%s\n", hostandport ? hostandport : "NULL");
1437                 printf("Diag: path=%s\n", path ? path : "NULL");
1438                 conn = NULL;
1439         } else if (protocol == PROTO_GIT) {
1440                 conn = git_connect_git(fd, hostandport, path, prog, version, flags);
1441                 conn->trace2_child_class = "transport/git";
1442         } else {
1443                 struct strbuf cmd = STRBUF_INIT;
1444                 const char *const *var;
1445
1446                 conn = xmalloc(sizeof(*conn));
1447                 child_process_init(conn);
1448
1449                 if (looks_like_command_line_option(path))
1450                         die(_("strange pathname '%s' blocked"), path);
1451
1452                 strbuf_addstr(&cmd, prog);
1453                 strbuf_addch(&cmd, ' ');
1454                 sq_quote_buf(&cmd, path);
1455
1456                 /* remove repo-local variables from the environment */
1457                 for (var = local_repo_env; *var; var++)
1458                         strvec_push(&conn->env, *var);
1459
1460                 conn->use_shell = 1;
1461                 conn->in = conn->out = -1;
1462                 if (protocol == PROTO_SSH) {
1463                         char *ssh_host = hostandport;
1464                         const char *port = NULL;
1465                         transport_check_allowed("ssh");
1466                         get_host_and_port(&ssh_host, &port);
1467
1468                         if (!port)
1469                                 port = get_port(ssh_host);
1470
1471                         if (flags & CONNECT_DIAG_URL) {
1472                                 printf("Diag: url=%s\n", url ? url : "NULL");
1473                                 printf("Diag: protocol=%s\n", prot_name(protocol));
1474                                 printf("Diag: userandhost=%s\n", ssh_host ? ssh_host : "NULL");
1475                                 printf("Diag: port=%s\n", port ? port : "NONE");
1476                                 printf("Diag: path=%s\n", path ? path : "NULL");
1477
1478                                 free(hostandport);
1479                                 free(path);
1480                                 free(conn);
1481                                 strbuf_release(&cmd);
1482                                 return NULL;
1483                         }
1484                         conn->trace2_child_class = "transport/ssh";
1485                         fill_ssh_args(conn, ssh_host, port, version, flags);
1486                 } else {
1487                         transport_check_allowed("file");
1488                         conn->trace2_child_class = "transport/file";
1489                         if (version > 0) {
1490                                 strvec_pushf(&conn->env,
1491                                              GIT_PROTOCOL_ENVIRONMENT "=version=%d",
1492                                              version);
1493                         }
1494                 }
1495                 strvec_push(&conn->args, cmd.buf);
1496
1497                 if (start_command(conn))
1498                         die(_("unable to fork"));
1499
1500                 fd[0] = conn->out; /* read from child's stdout */
1501                 fd[1] = conn->in;  /* write to child's stdin */
1502                 strbuf_release(&cmd);
1503         }
1504         free(hostandport);
1505         free(path);
1506         return conn;
1507 }
1508
1509 int finish_connect(struct child_process *conn)
1510 {
1511         int code;
1512         if (!conn || git_connection_is_socket(conn))
1513                 return 0;
1514
1515         code = finish_command(conn);
1516         free(conn);
1517         return code;
1518 }