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
  12 static char *server_capabilities;
  13 static const char *parse_feature_value(const char *, const char *, int *);
  14
  15 static int check_ref(const char *name, int len, unsigned int flags)
  16 {
  17         if (!flags)
  18                 return 1;
  19
  20         if (len < 5 || memcmp(name, "refs/", 5))
  21                 return 0;
  22
  23         /* Skip the "refs/" part */
  24         name += 5;
  25         len -= 5;
  26
  27         /* REF_NORMAL means that we don't want the magic fake tag refs */
  28         if ((flags & REF_NORMAL) && check_refname_format(name, 0))
  29                 return 0;
  30
  31         /* REF_HEADS means that we want regular branch heads */
  32         if ((flags & REF_HEADS) && !memcmp(name, "heads/", 6))
  33                 return 1;
  34
  35         /* REF_TAGS means that we want tags */
  36         if ((flags & REF_TAGS) && !memcmp(name, "tags/", 5))
  37                 return 1;
  38
  39         /* All type bits clear means that we are ok with anything */
  40         return !(flags & ~REF_NORMAL);
  41 }
  42
  43 int check_ref_type(const struct ref *ref, int flags)
  44 {
  45         return check_ref(ref->name, strlen(ref->name), flags);
  46 }
  47
  48 static void add_extra_have(struct extra_have_objects *extra, unsigned char *sha1)
  49 {
  50         ALLOC_GROW(extra->array, extra->nr + 1, extra->alloc);
  51         hashcpy(&(extra->array[extra->nr][0]), sha1);
  52         extra->nr++;
  53 }
  54
  55 static void die_initial_contact(int got_at_least_one_head)
  56 {
  57         if (got_at_least_one_head)
  58                 die("The remote end hung up upon initial contact");
  59         else
  60                 die("Could not read from remote repository.\n\n"
  61                     "Please make sure you have the correct access rights\n"
  62                     "and the repository exists.");
  63 }
  64
  65 static void parse_one_symref_info(struct string_list *symref, const char *val, int len)
  66 {
  67         char *sym, *target;
  68         struct string_list_item *item;
  69
  70         if (!len)
  71                 return; /* just "symref" */
  72         /* e.g. "symref=HEAD:refs/heads/master" */
  73         sym = xmalloc(len + 1);
  74         memcpy(sym, val, len);
  75         sym[len] = '\0';
  76         target = strchr(sym, ':');
  77         if (!target)
  78                 /* just "symref=something" */
  79                 goto reject;
  80         *(target++) = '\0';
  81         if (check_refname_format(sym, REFNAME_ALLOW_ONELEVEL) ||
  82             check_refname_format(target, REFNAME_ALLOW_ONELEVEL))
  83                 /* "symref=bogus:pair */
  84                 goto reject;
  85         item = string_list_append(symref, sym);
  86         item->util = target;
  87         return;
  88 reject:
  89         free(sym);
  90         return;
  91 }
  92
  93 static void annotate_refs_with_symref_info(struct ref *ref)
  94 {
  95         struct string_list symref = STRING_LIST_INIT_DUP;
  96         const char *feature_list = server_capabilities;
  97
  98         while (feature_list) {
  99                 int len;
 100                 const char *val;
 101
 102                 val = parse_feature_value(feature_list, "symref", &len);
 103                 if (!val)
 104                         break;
 105                 parse_one_symref_info(&symref, val, len);
 106                 feature_list = val + 1;
 107         }
 108         sort_string_list(&symref);
 109
 110         for (; ref; ref = ref->next) {
 111                 struct string_list_item *item;
 112                 item = string_list_lookup(&symref, ref->name);
 113                 if (!item)
 114                         continue;
 115                 ref->symref = xstrdup((char *)item->util);
 116         }
 117         string_list_clear(&symref, 0);
 118 }
 119
 120 /*
 121  * Read all the refs from the other end
 122  */
 123 struct ref **get_remote_heads(int in, char *src_buf, size_t src_len,
 124                               struct ref **list, unsigned int flags,
 125                               struct extra_have_objects *extra_have)
 126 {
 127         struct ref **orig_list = list;
 128         int got_at_least_one_head = 0;
 129
 130         *list = NULL;
 131         for (;;) {
 132                 struct ref *ref;
 133                 unsigned char old_sha1[20];
 134                 char *name;
 135                 int len, name_len;
 136                 char *buffer = packet_buffer;
 137
 138                 len = packet_read(in, &src_buf, &src_len,
 139                                   packet_buffer, sizeof(packet_buffer),
 140                                   PACKET_READ_GENTLE_ON_EOF |
 141                                   PACKET_READ_CHOMP_NEWLINE);
 142                 if (len < 0)
 143                         die_initial_contact(got_at_least_one_head);
 144
 145                 if (!len)
 146                         break;
 147
 148                 if (len > 4 && !prefixcmp(buffer, "ERR "))
 149                         die("remote error: %s", buffer + 4);
 150
 151                 if (len < 42 || get_sha1_hex(buffer, old_sha1) || buffer[40] != ' ')
 152                         die("protocol error: expected sha/ref, got '%s'", buffer);
 153                 name = buffer + 41;
 154
 155                 name_len = strlen(name);
 156                 if (len != name_len + 41) {
 157                         free(server_capabilities);
 158                         server_capabilities = xstrdup(name + name_len + 1);
 159                 }
 160
 161                 if (extra_have &&
 162                     name_len == 5 && !memcmp(".have", name, 5)) {
 163                         add_extra_have(extra_have, old_sha1);
 164                         continue;
 165                 }
 166
 167                 if (!check_ref(name, name_len, flags))
 168                         continue;
 169                 ref = alloc_ref(buffer + 41);
 170                 hashcpy(ref->old_sha1, old_sha1);
 171                 *list = ref;
 172                 list = &ref->next;
 173                 got_at_least_one_head = 1;
 174         }
 175
 176         annotate_refs_with_symref_info(*orig_list);
 177
 178         return list;
 179 }
 180
 181 static const char *parse_feature_value(const char *feature_list, const char *feature, int *lenp)
 182 {
 183         int len;
 184
 185         if (!feature_list)
 186                 return NULL;
 187
 188         len = strlen(feature);
 189         while (*feature_list) {
 190                 const char *found = strstr(feature_list, feature);
 191                 if (!found)
 192                         return NULL;
 193                 if (feature_list == found || isspace(found[-1])) {
 194                         const char *value = found + len;
 195                         /* feature with no value (e.g., "thin-pack") */
 196                         if (!*value || isspace(*value)) {
 197                                 if (lenp)
 198                                         *lenp = 0;
 199                                 return value;
 200                         }
 201                         /* feature with a value (e.g., "agent=git/1.2.3") */
 202                         else if (*value == '=') {
 203                                 value++;
 204                                 if (lenp)
 205                                         *lenp = strcspn(value, " \t\n");
 206                                 return value;
 207                         }
 208                         /*
 209                          * otherwise we matched a substring of another feature;
 210                          * keep looking
 211                          */
 212                 }
 213                 feature_list = found + 1;
 214         }
 215         return NULL;
 216 }
 217
 218 int parse_feature_request(const char *feature_list, const char *feature)
 219 {
 220         return !!parse_feature_value(feature_list, feature, NULL);
 221 }
 222
 223 const char *server_feature_value(const char *feature, int *len)
 224 {
 225         return parse_feature_value(server_capabilities, feature, len);
 226 }
 227
 228 int server_supports(const char *feature)
 229 {
 230         return !!server_feature_value(feature, NULL);
 231 }
 232
 233 enum protocol {
 234         PROTO_LOCAL = 1,
 235         PROTO_SSH,
 236         PROTO_GIT
 237 };
 238
 239 static const char *prot_name(enum protocol protocol)
 240 {
 241         switch (protocol) {
 242                 case PROTO_LOCAL:
 243                         return "file";
 244                 case PROTO_SSH:
 245                         return "ssh";
 246                 case PROTO_GIT:
 247                         return "git";
 248                 default:
 249                         return "unkown protocol";
 250         }
 251 }
 252
 253 static enum protocol get_protocol(const char *name)
 254 {
 255         if (!strcmp(name, "ssh"))
 256                 return PROTO_SSH;
 257         if (!strcmp(name, "git"))
 258                 return PROTO_GIT;
 259         if (!strcmp(name, "git+ssh"))
 260                 return PROTO_SSH;
 261         if (!strcmp(name, "ssh+git"))
 262                 return PROTO_SSH;
 263         if (!strcmp(name, "file"))
 264                 return PROTO_LOCAL;
 265         die("I don't handle protocol '%s'", name);
 266 }
 267
 268 #define STR_(s) # s
 269 #define STR(s)  STR_(s)
 270
 271 static void get_host_and_port(char **host, const char **port)
 272 {
 273         char *colon, *end;
 274
 275         if (*host[0] == '[') {
 276                 end = strchr(*host + 1, ']');
 277                 if (end) {
 278                         *end = 0;
 279                         end++;
 280                         (*host)++;
 281                 } else
 282                         end = *host;
 283         } else
 284                 end = *host;
 285         colon = strchr(end, ':');
 286
 287         if (colon) {
 288                 *colon = 0;
 289                 *port = colon + 1;
 290         }
 291 }
 292
 293 static void enable_keepalive(int sockfd)
 294 {
 295         int ka = 1;
 296
 297         if (setsockopt(sockfd, SOL_SOCKET, SO_KEEPALIVE, &ka, sizeof(ka)) < 0)
 298                 fprintf(stderr, "unable to set SO_KEEPALIVE on socket: %s\n",
 299                         strerror(errno));
 300 }
 301
 302 #ifndef NO_IPV6
 303
 304 static const char *ai_name(const struct addrinfo *ai)
 305 {
 306         static char addr[NI_MAXHOST];
 307         if (getnameinfo(ai->ai_addr, ai->ai_addrlen, addr, sizeof(addr), NULL, 0,
 308                         NI_NUMERICHOST) != 0)
 309                 strcpy(addr, "(unknown)");
 310
 311         return addr;
 312 }
 313
 314 /*
 315  * Returns a connected socket() fd, or else die()s.
 316  */
 317 static int git_tcp_connect_sock(char *host, int flags)
 318 {
 319         struct strbuf error_message = STRBUF_INIT;
 320         int sockfd = -1;
 321         const char *port = STR(DEFAULT_GIT_PORT);
 322         struct addrinfo hints, *ai0, *ai;
 323         int gai;
 324         int cnt = 0;
 325
 326         get_host_and_port(&host, &port);
 327         if (!*port)
 328                 port = "<none>";
 329
 330         memset(&hints, 0, sizeof(hints));
 331         hints.ai_socktype = SOCK_STREAM;
 332         hints.ai_protocol = IPPROTO_TCP;
 333
 334         if (flags & CONNECT_VERBOSE)
 335                 fprintf(stderr, "Looking up %s ... ", host);
 336
 337         gai = getaddrinfo(host, port, &hints, &ai);
 338         if (gai)
 339                 die("Unable to look up %s (port %s) (%s)", host, port, gai_strerror(gai));
 340
 341         if (flags & CONNECT_VERBOSE)
 342                 fprintf(stderr, "done.\nConnecting to %s (port %s) ... ", host, port);
 343
 344         for (ai0 = ai; ai; ai = ai->ai_next, cnt++) {
 345                 sockfd = socket(ai->ai_family,
 346                                 ai->ai_socktype, ai->ai_protocol);
 347                 if ((sockfd < 0) ||
 348                     (connect(sockfd, ai->ai_addr, ai->ai_addrlen) < 0)) {
 349                         strbuf_addf(&error_message, "%s[%d: %s]: errno=%s\n",
 350                                     host, cnt, ai_name(ai), strerror(errno));
 351                         if (0 <= sockfd)
 352                                 close(sockfd);
 353                         sockfd = -1;
 354                         continue;
 355                 }
 356                 if (flags & CONNECT_VERBOSE)
 357                         fprintf(stderr, "%s ", ai_name(ai));
 358                 break;
 359         }
 360
 361         freeaddrinfo(ai0);
 362
 363         if (sockfd < 0)
 364                 die("unable to connect to %s:\n%s", host, error_message.buf);
 365
 366         enable_keepalive(sockfd);
 367
 368         if (flags & CONNECT_VERBOSE)
 369                 fprintf(stderr, "done.\n");
 370
 371         strbuf_release(&error_message);
 372
 373         return sockfd;
 374 }
 375
 376 #else /* NO_IPV6 */
 377
 378 /*
 379  * Returns a connected socket() fd, or else die()s.
 380  */
 381 static int git_tcp_connect_sock(char *host, int flags)
 382 {
 383         struct strbuf error_message = STRBUF_INIT;
 384         int sockfd = -1;
 385         const char *port = STR(DEFAULT_GIT_PORT);
 386         char *ep;
 387         struct hostent *he;
 388         struct sockaddr_in sa;
 389         char **ap;
 390         unsigned int nport;
 391         int cnt;
 392
 393         get_host_and_port(&host, &port);
 394
 395         if (flags & CONNECT_VERBOSE)
 396                 fprintf(stderr, "Looking up %s ... ", host);
 397
 398         he = gethostbyname(host);
 399         if (!he)
 400                 die("Unable to look up %s (%s)", host, hstrerror(h_errno));
 401         nport = strtoul(port, &ep, 10);
 402         if ( ep == port || *ep ) {
 403                 /* Not numeric */
 404                 struct servent *se = getservbyname(port,"tcp");
 405                 if ( !se )
 406                         die("Unknown port %s", port);
 407                 nport = se->s_port;
 408         }
 409
 410         if (flags & CONNECT_VERBOSE)
 411                 fprintf(stderr, "done.\nConnecting to %s (port %s) ... ", host, port);
 412
 413         for (cnt = 0, ap = he->h_addr_list; *ap; ap++, cnt++) {
 414                 memset(&sa, 0, sizeof sa);
 415                 sa.sin_family = he->h_addrtype;
 416                 sa.sin_port = htons(nport);
 417                 memcpy(&sa.sin_addr, *ap, he->h_length);
 418
 419                 sockfd = socket(he->h_addrtype, SOCK_STREAM, 0);
 420                 if ((sockfd < 0) ||
 421                     connect(sockfd, (struct sockaddr *)&sa, sizeof sa) < 0) {
 422                         strbuf_addf(&error_message, "%s[%d: %s]: errno=%s\n",
 423                                 host,
 424                                 cnt,
 425                                 inet_ntoa(*(struct in_addr *)&sa.sin_addr),
 426                                 strerror(errno));
 427                         if (0 <= sockfd)
 428                                 close(sockfd);
 429                         sockfd = -1;
 430                         continue;
 431                 }
 432                 if (flags & CONNECT_VERBOSE)
 433                         fprintf(stderr, "%s ",
 434                                 inet_ntoa(*(struct in_addr *)&sa.sin_addr));
 435                 break;
 436         }
 437
 438         if (sockfd < 0)
 439                 die("unable to connect to %s:\n%s", host, error_message.buf);
 440
 441         enable_keepalive(sockfd);
 442
 443         if (flags & CONNECT_VERBOSE)
 444                 fprintf(stderr, "done.\n");
 445
 446         return sockfd;
 447 }
 448
 449 #endif /* NO_IPV6 */
 450
 451
 452 static void git_tcp_connect(int fd[2], char *host, int flags)
 453 {
 454         int sockfd = git_tcp_connect_sock(host, flags);
 455
 456         fd[0] = sockfd;
 457         fd[1] = dup(sockfd);
 458 }
 459
 460
 461 static char *git_proxy_command;
 462
 463 static int git_proxy_command_options(const char *var, const char *value,
 464                 void *cb)
 465 {
 466         if (!strcmp(var, "core.gitproxy")) {
 467                 const char *for_pos;
 468                 int matchlen = -1;
 469                 int hostlen;
 470                 const char *rhost_name = cb;
 471                 int rhost_len = strlen(rhost_name);
 472
 473                 if (git_proxy_command)
 474                         return 0;
 475                 if (!value)
 476                         return config_error_nonbool(var);
 477                 /* [core]
 478                  * ;# matches www.kernel.org as well
 479                  * gitproxy = netcatter-1 for kernel.org
 480                  * gitproxy = netcatter-2 for sample.xz
 481                  * gitproxy = netcatter-default
 482                  */
 483                 for_pos = strstr(value, " for ");
 484                 if (!for_pos)
 485                         /* matches everybody */
 486                         matchlen = strlen(value);
 487                 else {
 488                         hostlen = strlen(for_pos + 5);
 489                         if (rhost_len < hostlen)
 490                                 matchlen = -1;
 491                         else if (!strncmp(for_pos + 5,
 492                                           rhost_name + rhost_len - hostlen,
 493                                           hostlen) &&
 494                                  ((rhost_len == hostlen) ||
 495                                   rhost_name[rhost_len - hostlen -1] == '.'))
 496                                 matchlen = for_pos - value;
 497                         else
 498                                 matchlen = -1;
 499                 }
 500                 if (0 <= matchlen) {
 501                         /* core.gitproxy = none for kernel.org */
 502                         if (matchlen == 4 &&
 503                             !memcmp(value, "none", 4))
 504                                 matchlen = 0;
 505                         git_proxy_command = xmemdupz(value, matchlen);
 506                 }
 507                 return 0;
 508         }
 509
 510         return git_default_config(var, value, cb);
 511 }
 512
 513 static int git_use_proxy(const char *host)
 514 {
 515         git_proxy_command = getenv("GIT_PROXY_COMMAND");
 516         git_config(git_proxy_command_options, (void*)host);
 517         return (git_proxy_command && *git_proxy_command);
 518 }
 519
 520 static struct child_process *git_proxy_connect(int fd[2], char *host)
 521 {
 522         const char *port = STR(DEFAULT_GIT_PORT);
 523         const char **argv;
 524         struct child_process *proxy;
 525
 526         get_host_and_port(&host, &port);
 527
 528         argv = xmalloc(sizeof(*argv) * 4);
 529         argv[0] = git_proxy_command;
 530         argv[1] = host;
 531         argv[2] = port;
 532         argv[3] = NULL;
 533         proxy = xcalloc(1, sizeof(*proxy));
 534         proxy->argv = argv;
 535         proxy->in = -1;
 536         proxy->out = -1;
 537         if (start_command(proxy))
 538                 die("cannot start proxy %s", argv[0]);
 539         fd[0] = proxy->out; /* read from proxy stdout */
 540         fd[1] = proxy->in;  /* write to proxy stdin */
 541         return proxy;
 542 }
 543
 544 static char *get_port(char *host)
 545 {
 546         char *end;
 547         char *p = strchr(host, ':');
 548
 549         if (p) {
 550                 long port = strtol(p + 1, &end, 10);
 551                 if (end != p + 1 && *end == '\0' && 0 <= port && port < 65536) {
 552                         *p = '\0';
 553                         return p+1;
 554                 }
 555         }
 556
 557         return NULL;
 558 }
 559
 560 /*
 561  * Extract protocol and relevant parts from the specified connection URL.
 562  * The caller must free() the returned strings.
 563  */
 564 static enum protocol parse_connect_url(const char *url_orig, char **ret_host,
 565                                        char **ret_port, char **ret_path)
 566 {
 567         char *url;
 568         char *host, *path;
 569         char *end;
 570         int c;
 571         enum protocol protocol = PROTO_LOCAL;
 572         int free_path = 0;
 573         char *port = NULL;
 574
 575         if (is_url(url_orig))
 576                 url = url_decode(url_orig);
 577         else
 578                 url = xstrdup(url_orig);
 579
 580         host = strstr(url, "://");
 581         if (host) {
 582                 *host = '\0';
 583                 protocol = get_protocol(url);
 584                 host += 3;
 585                 c = '/';
 586         } else {
 587                 host = url;
 588                 c = ':';
 589         }
 590
 591         /*
 592          * Don't do destructive transforms with git:// as that
 593          * protocol code does '[]' unwrapping of its own.
 594          */
 595         if (host[0] == '[') {
 596                 end = strchr(host + 1, ']');
 597                 if (end) {
 598                         if (protocol != PROTO_GIT) {
 599                                 *end = 0;
 600                                 host++;
 601                         }
 602                         end++;
 603                 } else
 604                         end = host;
 605         } else
 606                 end = host;
 607
 608         path = strchr(end, c);
 609         if (path && !has_dos_drive_prefix(end)) {
 610                 if (c == ':') {
 611                         if (host != url || path < strchrnul(host, '/')) {
 612                                 protocol = PROTO_SSH;
 613                                 *path++ = '\0';
 614                         } else /* '/' in the host part, assume local path */
 615                                 path = end;
 616                 }
 617         } else
 618                 path = end;
 619
 620         if (!path || !*path)
 621                 die("No path specified. See 'man git-pull' for valid url syntax");
 622
 623         /*
 624          * null-terminate hostname and point path to ~ for URL's like this:
 625          *    ssh://host.xz/~user/repo
 626          */
 627         if (protocol != PROTO_LOCAL && host != url) {
 628                 char *ptr = path;
 629                 if (path[1] == '~')
 630                         path++;
 631                 else {
 632                         path = xstrdup(ptr);
 633                         free_path = 1;
 634                 }
 635
 636                 *ptr = '\0';
 637         }
 638
 639         /*
 640          * Add support for ssh port: ssh://host.xy:<port>/...
 641          */
 642         if (protocol == PROTO_SSH && host != url)
 643                 port = get_port(end);
 644
 645         *ret_host = xstrdup(host);
 646         if (port)
 647                 *ret_port = xstrdup(port);
 648         else
 649                 *ret_port = NULL;
 650         if (free_path)
 651                 *ret_path = path;
 652         else
 653                 *ret_path = xstrdup(path);
 654         free(url);
 655         return protocol;
 656 }
 657
 658 static struct child_process no_fork;
 659
 660 /*
 661  * This returns a dummy child_process if the transport protocol does not
 662  * need fork(2), or a struct child_process object if it does.  Once done,
 663  * finish the connection with finish_connect() with the value returned from
 664  * this function (it is safe to call finish_connect() with NULL to support
 665  * the former case).
 666  *
 667  * If it returns, the connect is successful; it just dies on errors (this
 668  * will hopefully be changed in a libification effort, to return NULL when
 669  * the connection failed).
 670  */
 671 struct child_process *git_connect(int fd[2], const char *url,
 672                                   const char *prog, int flags)
 673 {
 674         char *host, *path;
 675         struct child_process *conn = &no_fork;
 676         enum protocol protocol;
 677         char *port;
 678         const char **arg;
 679         struct strbuf cmd = STRBUF_INIT;
 680
 681         /* Without this we cannot rely on waitpid() to tell
 682          * what happened to our children.
 683          */
 684         signal(SIGCHLD, SIG_DFL);
 685
 686         protocol = parse_connect_url(url, &host, &port, &path);
 687         if (flags & CONNECT_DIAG_URL) {
 688                 printf("Diag: url=%s\n", url ? url : "NULL");
 689                 printf("Diag: protocol=%s\n", prot_name(protocol));
 690                 printf("Diag: hostandport=%s", host ? host : "NULL");
 691                 if (port)
 692                         printf(":%s\n", port);
 693                 else
 694                         printf("\n");
 695                 printf("Diag: path=%s\n", path ? path : "NULL");
 696                 free(host);
 697                 free(port);
 698                 free(path);
 699                 return NULL;
 700         }
 701
 702         if (protocol == PROTO_GIT) {
 703                 /* These underlying connection commands die() if they
 704                  * cannot connect.
 705                  */
 706                 char *target_host = xstrdup(host);
 707                 if (git_use_proxy(host))
 708                         conn = git_proxy_connect(fd, host);
 709                 else
 710                         git_tcp_connect(fd, host, flags);
 711                 /*
 712                  * Separate original protocol components prog and path
 713                  * from extended host header with a NUL byte.
 714                  *
 715                  * Note: Do not add any other headers here!  Doing so
 716                  * will cause older git-daemon servers to crash.
 717                  */
 718                 packet_write(fd[1],
 719                              "%s %s%chost=%s%c",
 720                              prog, path, 0,
 721                              target_host, 0);
 722                 free(target_host);
 723                 free(host);
 724                 free(port);
 725                 free(path);
 726                 return conn;
 727         }
 728
 729         conn = xcalloc(1, sizeof(*conn));
 730
 731         strbuf_addstr(&cmd, prog);
 732         strbuf_addch(&cmd, ' ');
 733         sq_quote_buf(&cmd, path);
 734
 735         conn->in = conn->out = -1;
 736         conn->argv = arg = xcalloc(7, sizeof(*arg));
 737         if (protocol == PROTO_SSH) {
 738                 const char *ssh = getenv("GIT_SSH");
 739                 int putty = ssh && strcasestr(ssh, "plink");
 740                 if (!ssh) ssh = "ssh";
 741
 742                 *arg++ = ssh;
 743                 if (putty && !strcasestr(ssh, "tortoiseplink"))
 744                         *arg++ = "-batch";
 745                 if (port) {
 746                         /* P is for PuTTY, p is for OpenSSH */
 747                         *arg++ = putty ? "-P" : "-p";
 748                         *arg++ = port;
 749                 }
 750                 *arg++ = host;
 751         }
 752         else {
 753                 /* remove repo-local variables from the environment */
 754                 conn->env = local_repo_env;
 755                 conn->use_shell = 1;
 756         }
 757         *arg++ = cmd.buf;
 758         *arg = NULL;
 759
 760         if (start_command(conn))
 761                 die("unable to fork");
 762
 763         fd[0] = conn->out; /* read from child's stdout */
 764         fd[1] = conn->in;  /* write to child's stdin */
 765         strbuf_release(&cmd);
 766         free(host);
 767         free(port);
 768         free(path);
 769         return conn;
 770 }
 771
 772 int git_connection_is_socket(struct child_process *conn)
 773 {
 774         return conn == &no_fork;
 775 }
 776
 777 int finish_connect(struct child_process *conn)
 778 {
 779         int code;
 780         if (!conn || git_connection_is_socket(conn))
 781                 return 0;
 782
 783         code = finish_command(conn);
 784         free(conn->argv);
 785         free(conn);
 786         return code;
 787 }