connect.c

   1 #include "git-compat-util.h"
   2 #include "cache.h"
   3 #include "pkt-line.h"
   4 #include "quote.h"
   5 #include "refs.h"
   6 #include "run-command.h"
   7 #include "remote.h"
   8 #include "connect.h"
   9 #include "url.h"
  10 #include "string-list.h"
  11 #include "sha1-array.h"
  12 #include "transport.h"
  13
  14 static char *server_capabilities;
  15 static const char *parse_feature_value(const char *, const char *, int *);
  16
  17 static int check_ref(const char *name, unsigned int flags)
  18 {
  19         if (!flags)
  20                 return 1;
  21
  22         if (!skip_prefix(name, "refs/", &name))
  23                 return 0;
  24
  25         /* REF_NORMAL means that we don't want the magic fake tag refs */
  26         if ((flags & REF_NORMAL) && check_refname_format(name, 0))
  27                 return 0;
  28
  29         /* REF_HEADS means that we want regular branch heads */
  30         if ((flags & REF_HEADS) && starts_with(name, "heads/"))
  31                 return 1;
  32
  33         /* REF_TAGS means that we want tags */
  34         if ((flags & REF_TAGS) && starts_with(name, "tags/"))
  35                 return 1;
  36
  37         /* All type bits clear means that we are ok with anything */
  38         return !(flags & ~REF_NORMAL);
  39 }
  40
  41 int check_ref_type(const struct ref *ref, int flags)
  42 {
  43         return check_ref(ref->name, flags);
  44 }
  45
  46 static void die_initial_contact(int got_at_least_one_head)
  47 {
  48         if (got_at_least_one_head)
  49                 die("The remote end hung up upon initial contact");
  50         else
  51                 die("Could not read from remote repository.\n\n"
  52                     "Please make sure you have the correct access rights\n"
  53                     "and the repository exists.");
  54 }
  55
  56 static void parse_one_symref_info(struct string_list *symref, const char *val, int len)
  57 {
  58         char *sym, *target;
  59         struct string_list_item *item;
  60
  61         if (!len)
  62                 return; /* just "symref" */
  63         /* e.g. "symref=HEAD:refs/heads/master" */
  64         sym = xmemdupz(val, len);
  65         target = strchr(sym, ':');
  66         if (!target)
  67                 /* just "symref=something" */
  68                 goto reject;
  69         *(target++) = '\0';
  70         if (check_refname_format(sym, REFNAME_ALLOW_ONELEVEL) ||
  71             check_refname_format(target, REFNAME_ALLOW_ONELEVEL))
  72                 /* "symref=bogus:pair */
  73                 goto reject;
  74         item = string_list_append(symref, sym);
  75         item->util = target;
  76         return;
  77 reject:
  78         free(sym);
  79         return;
  80 }
  81
  82 static void annotate_refs_with_symref_info(struct ref *ref)
  83 {
  84         struct string_list symref = STRING_LIST_INIT_DUP;
  85         const char *feature_list = server_capabilities;
  86
  87         while (feature_list) {
  88                 int len;
  89                 const char *val;
  90
  91                 val = parse_feature_value(feature_list, "symref", &len);
  92                 if (!val)
  93                         break;
  94                 parse_one_symref_info(&symref, val, len);
  95                 feature_list = val + 1;
  96         }
  97         string_list_sort(&symref);
  98
  99         for (; ref; ref = ref->next) {
 100                 struct string_list_item *item;
 101                 item = string_list_lookup(&symref, ref->name);
 102                 if (!item)
 103                         continue;
 104                 ref->symref = xstrdup((char *)item->util);
 105         }
 106         string_list_clear(&symref, 0);
 107 }
 108
 109 /*
 110  * Read all the refs from the other end
 111  */
 112 struct ref **get_remote_heads(int in, char *src_buf, size_t src_len,
 113                               struct ref **list, unsigned int flags,
 114                               struct sha1_array *extra_have,
 115                               struct sha1_array *shallow_points)
 116 {
 117         struct ref **orig_list = list;
 118         int got_at_least_one_head = 0;
 119
 120         *list = NULL;
 121         for (;;) {
 122                 struct ref *ref;
 123                 struct object_id old_oid;
 124                 char *name;
 125                 int len, name_len;
 126                 char *buffer = packet_buffer;
 127                 const char *arg;
 128
 129                 len = packet_read(in, &src_buf, &src_len,
 130                                   packet_buffer, sizeof(packet_buffer),
 131                                   PACKET_READ_GENTLE_ON_EOF |
 132                                   PACKET_READ_CHOMP_NEWLINE);
 133                 if (len < 0)
 134                         die_initial_contact(got_at_least_one_head);
 135
 136                 if (!len)
 137                         break;
 138
 139                 if (len > 4 && skip_prefix(buffer, "ERR ", &arg))
 140                         die("remote error: %s", arg);
 141
 142                 if (len == GIT_SHA1_HEXSZ + strlen("shallow ") &&
 143                         skip_prefix(buffer, "shallow ", &arg)) {
 144                         if (get_oid_hex(arg, &old_oid))
 145                                 die("protocol error: expected shallow sha-1, got '%s'", arg);
 146                         if (!shallow_points)
 147                                 die("repository on the other end cannot be shallow");
 148                         sha1_array_append(shallow_points, old_oid.hash);
 149                         continue;
 150                 }
 151
 152                 if (len < GIT_SHA1_HEXSZ + 2 || get_oid_hex(buffer, &old_oid) ||
 153                         buffer[GIT_SHA1_HEXSZ] != ' ')
 154                         die("protocol error: expected sha/ref, got '%s'", buffer);
 155                 name = buffer + GIT_SHA1_HEXSZ + 1;
 156
 157                 name_len = strlen(name);
 158                 if (len != name_len + GIT_SHA1_HEXSZ + 1) {
 159                         free(server_capabilities);
 160                         server_capabilities = xstrdup(name + name_len + 1);
 161                 }
 162
 163                 if (extra_have && !strcmp(name, ".have")) {
 164                         sha1_array_append(extra_have, old_oid.hash);
 165                         continue;
 166                 }
 167
 168                 if (!check_ref(name, flags))
 169                         continue;
 170                 ref = alloc_ref(buffer + GIT_SHA1_HEXSZ + 1);
 171                 oidcpy(&ref->old_oid, &old_oid);
 172                 *list = ref;
 173                 list = &ref->next;
 174                 got_at_least_one_head = 1;
 175         }
 176
 177         annotate_refs_with_symref_info(*orig_list);
 178
 179         return list;
 180 }
 181
 182 static const char *parse_feature_value(const char *feature_list, const char *feature, int *lenp)
 183 {
 184         int len;
 185
 186         if (!feature_list)
 187                 return NULL;
 188
 189         len = strlen(feature);
 190         while (*feature_list) {
 191                 const char *found = strstr(feature_list, feature);
 192                 if (!found)
 193                         return NULL;
 194                 if (feature_list == found || isspace(found[-1])) {
 195                         const char *value = found + len;
 196                         /* feature with no value (e.g., "thin-pack") */
 197                         if (!*value || isspace(*value)) {
 198                                 if (lenp)
 199                                         *lenp = 0;
 200                                 return value;
 201                         }
 202                         /* feature with a value (e.g., "agent=git/1.2.3") */
 203                         else if (*value == '=') {
 204                                 value++;
 205                                 if (lenp)
 206                                         *lenp = strcspn(value, " \t\n");
 207                                 return value;
 208                         }
 209                         /*
 210                          * otherwise we matched a substring of another feature;
 211                          * keep looking
 212                          */
 213                 }
 214                 feature_list = found + 1;
 215         }
 216         return NULL;
 217 }
 218
 219 int parse_feature_request(const char *feature_list, const char *feature)
 220 {
 221         return !!parse_feature_value(feature_list, feature, NULL);
 222 }
 223
 224 const char *server_feature_value(const char *feature, int *len)
 225 {
 226         return parse_feature_value(server_capabilities, feature, len);
 227 }
 228
 229 int server_supports(const char *feature)
 230 {
 231         return !!server_feature_value(feature, NULL);
 232 }
 233
 234 enum protocol {
 235         PROTO_LOCAL = 1,
 236         PROTO_FILE,
 237         PROTO_SSH,
 238         PROTO_GIT
 239 };
 240
 241 int url_is_local_not_ssh(const char *url)
 242 {
 243         const char *colon = strchr(url, ':');
 244         const char *slash = strchr(url, '/');
 245         return !colon || (slash && slash < colon) ||
 246                 has_dos_drive_prefix(url);
 247 }
 248
 249 static const char *prot_name(enum protocol protocol)
 250 {
 251         switch (protocol) {
 252                 case PROTO_LOCAL:
 253                 case PROTO_FILE:
 254                         return "file";
 255                 case PROTO_SSH:
 256                         return "ssh";
 257                 case PROTO_GIT:
 258                         return "git";
 259                 default:
 260                         return "unknown protocol";
 261         }
 262 }
 263
 264 static enum protocol get_protocol(const char *name)
 265 {
 266         if (!strcmp(name, "ssh"))
 267                 return PROTO_SSH;
 268         if (!strcmp(name, "git"))
 269                 return PROTO_GIT;
 270         if (!strcmp(name, "git+ssh")) /* deprecated - do not use */
 271                 return PROTO_SSH;
 272         if (!strcmp(name, "ssh+git")) /* deprecated - do not use */
 273                 return PROTO_SSH;
 274         if (!strcmp(name, "file"))
 275                 return PROTO_FILE;
 276         die("I don't handle protocol '%s'", name);
 277 }
 278
 279 static char *host_end(char **hoststart, int removebrackets)
 280 {
 281         char *host = *hoststart;
 282         char *end;
 283         char *start = strstr(host, "@[");
 284         if (start)
 285                 start++; /* Jump over '@' */
 286         else
 287                 start = host;
 288         if (start[0] == '[') {
 289                 end = strchr(start + 1, ']');
 290                 if (end) {
 291                         if (removebrackets) {
 292                                 *end = 0;
 293                                 memmove(start, start + 1, end - start);
 294                                 end++;
 295                         }
 296                 } else
 297                         end = host;
 298         } else
 299                 end = host;
 300         return end;
 301 }
 302
 303 #define STR_(s) # s
 304 #define STR(s)  STR_(s)
 305
 306 static void get_host_and_port(char **host, const char **port)
 307 {
 308         char *colon, *end;
 309         end = host_end(host, 1);
 310         colon = strchr(end, ':');
 311         if (colon) {
 312                 long portnr = strtol(colon + 1, &end, 10);
 313                 if (end != colon + 1 && *end == '\0' && 0 <= portnr && portnr < 65536) {
 314                         *colon = 0;
 315                         *port = colon + 1;
 316                 } else if (!colon[1]) {
 317                         *colon = 0;
 318                 }
 319         }
 320 }
 321
 322 static void enable_keepalive(int sockfd)
 323 {
 324         int ka = 1;
 325
 326         if (setsockopt(sockfd, SOL_SOCKET, SO_KEEPALIVE, &ka, sizeof(ka)) < 0)
 327                 fprintf(stderr, "unable to set SO_KEEPALIVE on socket: %s\n",
 328                         strerror(errno));
 329 }
 330
 331 #ifndef NO_IPV6
 332
 333 static const char *ai_name(const struct addrinfo *ai)
 334 {
 335         static char addr[NI_MAXHOST];
 336         if (getnameinfo(ai->ai_addr, ai->ai_addrlen, addr, sizeof(addr), NULL, 0,
 337                         NI_NUMERICHOST) != 0)
 338                 xsnprintf(addr, sizeof(addr), "(unknown)");
 339
 340         return addr;
 341 }
 342
 343 /*
 344  * Returns a connected socket() fd, or else die()s.
 345  */
 346 static int git_tcp_connect_sock(char *host, int flags)
 347 {
 348         struct strbuf error_message = STRBUF_INIT;
 349         int sockfd = -1;
 350         const char *port = STR(DEFAULT_GIT_PORT);
 351         struct addrinfo hints, *ai0, *ai;
 352         int gai;
 353         int cnt = 0;
 354
 355         get_host_and_port(&host, &port);
 356         if (!*port)
 357                 port = "<none>";
 358
 359         memset(&hints, 0, sizeof(hints));
 360         if (flags & CONNECT_IPV4)
 361                 hints.ai_family = AF_INET;
 362         else if (flags & CONNECT_IPV6)
 363                 hints.ai_family = AF_INET6;
 364         hints.ai_socktype = SOCK_STREAM;
 365         hints.ai_protocol = IPPROTO_TCP;
 366
 367         if (flags & CONNECT_VERBOSE)
 368                 fprintf(stderr, "Looking up %s ... ", host);
 369
 370         gai = getaddrinfo(host, port, &hints, &ai);
 371         if (gai)
 372                 die("Unable to look up %s (port %s) (%s)", host, port, gai_strerror(gai));
 373
 374         if (flags & CONNECT_VERBOSE)
 375                 fprintf(stderr, "done.\nConnecting to %s (port %s) ... ", host, port);
 376
 377         for (ai0 = ai; ai; ai = ai->ai_next, cnt++) {
 378                 sockfd = socket(ai->ai_family,
 379                                 ai->ai_socktype, ai->ai_protocol);
 380                 if ((sockfd < 0) ||
 381                     (connect(sockfd, ai->ai_addr, ai->ai_addrlen) < 0)) {
 382                         strbuf_addf(&error_message, "%s[%d: %s]: errno=%s\n",
 383                                     host, cnt, ai_name(ai), strerror(errno));
 384                         if (0 <= sockfd)
 385                                 close(sockfd);
 386                         sockfd = -1;
 387                         continue;
 388                 }
 389                 if (flags & CONNECT_VERBOSE)
 390                         fprintf(stderr, "%s ", ai_name(ai));
 391                 break;
 392         }
 393
 394         freeaddrinfo(ai0);
 395
 396         if (sockfd < 0)
 397                 die("unable to connect to %s:\n%s", host, error_message.buf);
 398
 399         enable_keepalive(sockfd);
 400
 401         if (flags & CONNECT_VERBOSE)
 402                 fprintf(stderr, "done.\n");
 403
 404         strbuf_release(&error_message);
 405
 406         return sockfd;
 407 }
 408
 409 #else /* NO_IPV6 */
 410
 411 /*
 412  * Returns a connected socket() fd, or else die()s.
 413  */
 414 static int git_tcp_connect_sock(char *host, int flags)
 415 {
 416         struct strbuf error_message = STRBUF_INIT;
 417         int sockfd = -1;
 418         const char *port = STR(DEFAULT_GIT_PORT);
 419         char *ep;
 420         struct hostent *he;
 421         struct sockaddr_in sa;
 422         char **ap;
 423         unsigned int nport;
 424         int cnt;
 425
 426         get_host_and_port(&host, &port);
 427
 428         if (flags & CONNECT_VERBOSE)
 429                 fprintf(stderr, "Looking up %s ... ", host);
 430
 431         he = gethostbyname(host);
 432         if (!he)
 433                 die("Unable to look up %s (%s)", host, hstrerror(h_errno));
 434         nport = strtoul(port, &ep, 10);
 435         if ( ep == port || *ep ) {
 436                 /* Not numeric */
 437                 struct servent *se = getservbyname(port,"tcp");
 438                 if ( !se )
 439                         die("Unknown port %s", port);
 440                 nport = se->s_port;
 441         }
 442
 443         if (flags & CONNECT_VERBOSE)
 444                 fprintf(stderr, "done.\nConnecting to %s (port %s) ... ", host, port);
 445
 446         for (cnt = 0, ap = he->h_addr_list; *ap; ap++, cnt++) {
 447                 memset(&sa, 0, sizeof sa);
 448                 sa.sin_family = he->h_addrtype;
 449                 sa.sin_port = htons(nport);
 450                 memcpy(&sa.sin_addr, *ap, he->h_length);
 451
 452                 sockfd = socket(he->h_addrtype, SOCK_STREAM, 0);
 453                 if ((sockfd < 0) ||
 454                     connect(sockfd, (struct sockaddr *)&sa, sizeof sa) < 0) {
 455                         strbuf_addf(&error_message, "%s[%d: %s]: errno=%s\n",
 456                                 host,
 457                                 cnt,
 458                                 inet_ntoa(*(struct in_addr *)&sa.sin_addr),
 459                                 strerror(errno));
 460                         if (0 <= sockfd)
 461                                 close(sockfd);
 462                         sockfd = -1;
 463                         continue;
 464                 }
 465                 if (flags & CONNECT_VERBOSE)
 466                         fprintf(stderr, "%s ",
 467                                 inet_ntoa(*(struct in_addr *)&sa.sin_addr));
 468                 break;
 469         }
 470
 471         if (sockfd < 0)
 472                 die("unable to connect to %s:\n%s", host, error_message.buf);
 473
 474         enable_keepalive(sockfd);
 475
 476         if (flags & CONNECT_VERBOSE)
 477                 fprintf(stderr, "done.\n");
 478
 479         return sockfd;
 480 }
 481
 482 #endif /* NO_IPV6 */
 483
 484
 485 static void git_tcp_connect(int fd[2], char *host, int flags)
 486 {
 487         int sockfd = git_tcp_connect_sock(host, flags);
 488
 489         fd[0] = sockfd;
 490         fd[1] = dup(sockfd);
 491 }
 492
 493
 494 static char *git_proxy_command;
 495
 496 static int git_proxy_command_options(const char *var, const char *value,
 497                 void *cb)
 498 {
 499         if (!strcmp(var, "core.gitproxy")) {
 500                 const char *for_pos;
 501                 int matchlen = -1;
 502                 int hostlen;
 503                 const char *rhost_name = cb;
 504                 int rhost_len = strlen(rhost_name);
 505
 506                 if (git_proxy_command)
 507                         return 0;
 508                 if (!value)
 509                         return config_error_nonbool(var);
 510                 /* [core]
 511                  * ;# matches www.kernel.org as well
 512                  * gitproxy = netcatter-1 for kernel.org
 513                  * gitproxy = netcatter-2 for sample.xz
 514                  * gitproxy = netcatter-default
 515                  */
 516                 for_pos = strstr(value, " for ");
 517                 if (!for_pos)
 518                         /* matches everybody */
 519                         matchlen = strlen(value);
 520                 else {
 521                         hostlen = strlen(for_pos + 5);
 522                         if (rhost_len < hostlen)
 523                                 matchlen = -1;
 524                         else if (!strncmp(for_pos + 5,
 525                                           rhost_name + rhost_len - hostlen,
 526                                           hostlen) &&
 527                                  ((rhost_len == hostlen) ||
 528                                   rhost_name[rhost_len - hostlen -1] == '.'))
 529                                 matchlen = for_pos - value;
 530                         else
 531                                 matchlen = -1;
 532                 }
 533                 if (0 <= matchlen) {
 534                         /* core.gitproxy = none for kernel.org */
 535                         if (matchlen == 4 &&
 536                             !memcmp(value, "none", 4))
 537                                 matchlen = 0;
 538                         git_proxy_command = xmemdupz(value, matchlen);
 539                 }
 540                 return 0;
 541         }
 542
 543         return git_default_config(var, value, cb);
 544 }
 545
 546 static int git_use_proxy(const char *host)
 547 {
 548         git_proxy_command = getenv("GIT_PROXY_COMMAND");
 549         git_config(git_proxy_command_options, (void*)host);
 550         return (git_proxy_command && *git_proxy_command);
 551 }
 552
 553 static struct child_process *git_proxy_connect(int fd[2], char *host)
 554 {
 555         const char *port = STR(DEFAULT_GIT_PORT);
 556         struct child_process *proxy;
 557
 558         get_host_and_port(&host, &port);
 559
 560         proxy = xmalloc(sizeof(*proxy));
 561         child_process_init(proxy);
 562         argv_array_push(&proxy->args, git_proxy_command);
 563         argv_array_push(&proxy->args, host);
 564         argv_array_push(&proxy->args, port);
 565         proxy->in = -1;
 566         proxy->out = -1;
 567         if (start_command(proxy))
 568                 die("cannot start proxy %s", git_proxy_command);
 569         fd[0] = proxy->out; /* read from proxy stdout */
 570         fd[1] = proxy->in;  /* write to proxy stdin */
 571         return proxy;
 572 }
 573
 574 static char *get_port(char *host)
 575 {
 576         char *end;
 577         char *p = strchr(host, ':');
 578
 579         if (p) {
 580                 long port = strtol(p + 1, &end, 10);
 581                 if (end != p + 1 && *end == '\0' && 0 <= port && port < 65536) {
 582                         *p = '\0';
 583                         return p+1;
 584                 }
 585         }
 586
 587         return NULL;
 588 }
 589
 590 /*
 591  * Extract protocol and relevant parts from the specified connection URL.
 592  * The caller must free() the returned strings.
 593  */
 594 static enum protocol parse_connect_url(const char *url_orig, char **ret_host,
 595                                        char **ret_path)
 596 {
 597         char *url;
 598         char *host, *path;
 599         char *end;
 600         int separator = '/';
 601         enum protocol protocol = PROTO_LOCAL;
 602
 603         if (is_url(url_orig))
 604                 url = url_decode(url_orig);
 605         else
 606                 url = xstrdup(url_orig);
 607
 608         host = strstr(url, "://");
 609         if (host) {
 610                 *host = '\0';
 611                 protocol = get_protocol(url);
 612                 host += 3;
 613         } else {
 614                 host = url;
 615                 if (!url_is_local_not_ssh(url)) {
 616                         protocol = PROTO_SSH;
 617                         separator = ':';
 618                 }
 619         }
 620
 621         /*
 622          * Don't do destructive transforms as protocol code does
 623          * '[]' unwrapping in get_host_and_port()
 624          */
 625         end = host_end(&host, 0);
 626
 627         if (protocol == PROTO_LOCAL)
 628                 path = end;
 629         else if (protocol == PROTO_FILE && has_dos_drive_prefix(end))
 630                 path = end; /* "file://$(pwd)" may be "file://C:/projects/repo" */
 631         else
 632                 path = strchr(end, separator);
 633
 634         if (!path || !*path)
 635                 die("No path specified. See 'man git-pull' for valid url syntax");
 636
 637         /*
 638          * null-terminate hostname and point path to ~ for URL's like this:
 639          *    ssh://host.xz/~user/repo
 640          */
 641
 642         end = path; /* Need to \0 terminate host here */
 643         if (separator == ':')
 644                 path++; /* path starts after ':' */
 645         if (protocol == PROTO_GIT || protocol == PROTO_SSH) {
 646                 if (path[1] == '~')
 647                         path++;
 648         }
 649
 650         path = xstrdup(path);
 651         *end = '\0';
 652
 653         *ret_host = xstrdup(host);
 654         *ret_path = path;
 655         free(url);
 656         return protocol;
 657 }
 658
 659 static struct child_process no_fork = CHILD_PROCESS_INIT;
 660
 661 /*
 662  * This returns a dummy child_process if the transport protocol does not
 663  * need fork(2), or a struct child_process object if it does.  Once done,
 664  * finish the connection with finish_connect() with the value returned from
 665  * this function (it is safe to call finish_connect() with NULL to support
 666  * the former case).
 667  *
 668  * If it returns, the connect is successful; it just dies on errors (this
 669  * will hopefully be changed in a libification effort, to return NULL when
 670  * the connection failed).
 671  */
 672 struct child_process *git_connect(int fd[2], const char *url,
 673                                   const char *prog, int flags)
 674 {
 675         char *hostandport, *path;
 676         struct child_process *conn = &no_fork;
 677         enum protocol protocol;
 678         struct strbuf cmd = STRBUF_INIT;
 679
 680         /* Without this we cannot rely on waitpid() to tell
 681          * what happened to our children.
 682          */
 683         signal(SIGCHLD, SIG_DFL);
 684
 685         protocol = parse_connect_url(url, &hostandport, &path);
 686         if ((flags & CONNECT_DIAG_URL) && (protocol != PROTO_SSH)) {
 687                 printf("Diag: url=%s\n", url ? url : "NULL");
 688                 printf("Diag: protocol=%s\n", prot_name(protocol));
 689                 printf("Diag: hostandport=%s\n", hostandport ? hostandport : "NULL");
 690                 printf("Diag: path=%s\n", path ? path : "NULL");
 691                 conn = NULL;
 692         } else if (protocol == PROTO_GIT) {
 693                 /*
 694                  * Set up virtual host information based on where we will
 695                  * connect, unless the user has overridden us in
 696                  * the environment.
 697                  */
 698                 char *target_host = getenv("GIT_OVERRIDE_VIRTUAL_HOST");
 699                 if (target_host)
 700                         target_host = xstrdup(target_host);
 701                 else
 702                         target_host = xstrdup(hostandport);
 703
 704                 transport_check_allowed("git");
 705
 706                 /* These underlying connection commands die() if they
 707                  * cannot connect.
 708                  */
 709                 if (git_use_proxy(hostandport))
 710                         conn = git_proxy_connect(fd, hostandport);
 711                 else
 712                         git_tcp_connect(fd, hostandport, flags);
 713                 /*
 714                  * Separate original protocol components prog and path
 715                  * from extended host header with a NUL byte.
 716                  *
 717                  * Note: Do not add any other headers here!  Doing so
 718                  * will cause older git-daemon servers to crash.
 719                  */
 720                 packet_write(fd[1],
 721                              "%s %s%chost=%s%c",
 722                              prog, path, 0,
 723                              target_host, 0);
 724                 free(target_host);
 725         } else {
 726                 conn = xmalloc(sizeof(*conn));
 727                 child_process_init(conn);
 728
 729                 strbuf_addstr(&cmd, prog);
 730                 strbuf_addch(&cmd, ' ');
 731                 sq_quote_buf(&cmd, path);
 732
 733                 /* remove repo-local variables from the environment */
 734                 conn->env = local_repo_env;
 735                 conn->use_shell = 1;
 736                 conn->in = conn->out = -1;
 737                 if (protocol == PROTO_SSH) {
 738                         const char *ssh;
 739                         int putty = 0, tortoiseplink = 0;
 740                         char *ssh_host = hostandport;
 741                         const char *port = NULL;
 742                         transport_check_allowed("ssh");
 743                         get_host_and_port(&ssh_host, &port);
 744
 745                         if (!port)
 746                                 port = get_port(ssh_host);
 747
 748                         if (flags & CONNECT_DIAG_URL) {
 749                                 printf("Diag: url=%s\n", url ? url : "NULL");
 750                                 printf("Diag: protocol=%s\n", prot_name(protocol));
 751                                 printf("Diag: userandhost=%s\n", ssh_host ? ssh_host : "NULL");
 752                                 printf("Diag: port=%s\n", port ? port : "NONE");
 753                                 printf("Diag: path=%s\n", path ? path : "NULL");
 754
 755                                 free(hostandport);
 756                                 free(path);
 757                                 free(conn);
 758                                 return NULL;
 759                         }
 760
 761                         ssh = getenv("GIT_SSH_COMMAND");
 762                         if (!ssh) {
 763                                 const char *base;
 764                                 char *ssh_dup;
 765
 766                                 /*
 767                                  * GIT_SSH is the no-shell version of
 768                                  * GIT_SSH_COMMAND (and must remain so for
 769                                  * historical compatibility).
 770                                  */
 771                                 conn->use_shell = 0;
 772
 773                                 ssh = getenv("GIT_SSH");
 774                                 if (!ssh)
 775                                         ssh = "ssh";
 776
 777                                 ssh_dup = xstrdup(ssh);
 778                                 base = basename(ssh_dup);
 779
 780                                 tortoiseplink = !strcasecmp(base, "tortoiseplink") ||
 781                                         !strcasecmp(base, "tortoiseplink.exe");
 782                                 putty = tortoiseplink ||
 783                                         !strcasecmp(base, "plink") ||
 784                                         !strcasecmp(base, "plink.exe");
 785
 786                                 free(ssh_dup);
 787                         }
 788
 789                         argv_array_push(&conn->args, ssh);
 790                         if (flags & CONNECT_IPV4)
 791                                 argv_array_push(&conn->args, "-4");
 792                         else if (flags & CONNECT_IPV6)
 793                                 argv_array_push(&conn->args, "-6");
 794                         if (tortoiseplink)
 795                                 argv_array_push(&conn->args, "-batch");
 796                         if (port) {
 797                                 /* P is for PuTTY, p is for OpenSSH */
 798                                 argv_array_push(&conn->args, putty ? "-P" : "-p");
 799                                 argv_array_push(&conn->args, port);
 800                         }
 801                         argv_array_push(&conn->args, ssh_host);
 802                 } else {
 803                         transport_check_allowed("file");
 804                 }
 805                 argv_array_push(&conn->args, cmd.buf);
 806
 807                 if (start_command(conn))
 808                         die("unable to fork");
 809
 810                 fd[0] = conn->out; /* read from child's stdout */
 811                 fd[1] = conn->in;  /* write to child's stdin */
 812                 strbuf_release(&cmd);
 813         }
 814         free(hostandport);
 815         free(path);
 816         return conn;
 817 }
 818
 819 int git_connection_is_socket(struct child_process *conn)
 820 {
 821         return conn == &no_fork;
 822 }
 823
 824 int finish_connect(struct child_process *conn)
 825 {
 826         int code;
 827         if (!conn || git_connection_is_socket(conn))
 828                 return 0;
 829
 830         code = finish_command(conn);
 831         free(conn);
 832         return code;
 833 }