connect.c

   1 #include "git-compat-util.h"
   2 #include "cache.h"
   3 #include "config.h"
   4 #include "pkt-line.h"
   5 #include "quote.h"
   6 #include "refs.h"
   7 #include "run-command.h"
   8 #include "remote.h"
   9 #include "connect.h"
  10 #include "url.h"
  11 #include "string-list.h"
  12 #include "sha1-array.h"
  13 #include "transport.h"
  14
  15 static char *server_capabilities;
  16 static const char *parse_feature_value(const char *, const char *, int *);
  17
  18 static int check_ref(const char *name, unsigned int flags)
  19 {
  20         if (!flags)
  21                 return 1;
  22
  23         if (!skip_prefix(name, "refs/", &name))
  24                 return 0;
  25
  26         /* REF_NORMAL means that we don't want the magic fake tag refs */
  27         if ((flags & REF_NORMAL) && check_refname_format(name, 0))
  28                 return 0;
  29
  30         /* REF_HEADS means that we want regular branch heads */
  31         if ((flags & REF_HEADS) && starts_with(name, "heads/"))
  32                 return 1;
  33
  34         /* REF_TAGS means that we want tags */
  35         if ((flags & REF_TAGS) && starts_with(name, "tags/"))
  36                 return 1;
  37
  38         /* All type bits clear means that we are ok with anything */
  39         return !(flags & ~REF_NORMAL);
  40 }
  41
  42 int check_ref_type(const struct ref *ref, int flags)
  43 {
  44         return check_ref(ref->name, flags);
  45 }
  46
  47 static void die_initial_contact(int unexpected)
  48 {
  49         if (unexpected)
  50                 die(_("The remote end hung up upon initial contact"));
  51         else
  52                 die(_("Could not read from remote repository.\n\n"
  53                       "Please make sure you have the correct access rights\n"
  54                       "and the repository exists."));
  55 }
  56
  57 static void parse_one_symref_info(struct string_list *symref, const char *val, int len)
  58 {
  59         char *sym, *target;
  60         struct string_list_item *item;
  61
  62         if (!len)
  63                 return; /* just "symref" */
  64         /* e.g. "symref=HEAD:refs/heads/master" */
  65         sym = xmemdupz(val, len);
  66         target = strchr(sym, ':');
  67         if (!target)
  68                 /* just "symref=something" */
  69                 goto reject;
  70         *(target++) = '\0';
  71         if (check_refname_format(sym, REFNAME_ALLOW_ONELEVEL) ||
  72             check_refname_format(target, REFNAME_ALLOW_ONELEVEL))
  73                 /* "symref=bogus:pair */
  74                 goto reject;
  75         item = string_list_append_nodup(symref, sym);
  76         item->util = target;
  77         return;
  78 reject:
  79         free(sym);
  80         return;
  81 }
  82
  83 static void annotate_refs_with_symref_info(struct ref *ref)
  84 {
  85         struct string_list symref = STRING_LIST_INIT_DUP;
  86         const char *feature_list = server_capabilities;
  87
  88         while (feature_list) {
  89                 int len;
  90                 const char *val;
  91
  92                 val = parse_feature_value(feature_list, "symref", &len);
  93                 if (!val)
  94                         break;
  95                 parse_one_symref_info(&symref, val, len);
  96                 feature_list = val + 1;
  97         }
  98         string_list_sort(&symref);
  99
 100         for (; ref; ref = ref->next) {
 101                 struct string_list_item *item;
 102                 item = string_list_lookup(&symref, ref->name);
 103                 if (!item)
 104                         continue;
 105                 ref->symref = xstrdup((char *)item->util);
 106         }
 107         string_list_clear(&symref, 0);
 108 }
 109
 110 /*
 111  * Read all the refs from the other end
 112  */
 113 struct ref **get_remote_heads(int in, char *src_buf, size_t src_len,
 114                               struct ref **list, unsigned int flags,
 115                               struct oid_array *extra_have,
 116                               struct oid_array *shallow_points)
 117 {
 118         struct ref **orig_list = list;
 119
 120         /*
 121          * A hang-up after seeing some response from the other end
 122          * means that it is unexpected, as we know the other end is
 123          * willing to talk to us.  A hang-up before seeing any
 124          * response does not necessarily mean an ACL problem, though.
 125          */
 126         int saw_response;
 127         int got_dummy_ref_with_capabilities_declaration = 0;
 128
 129         *list = NULL;
 130         for (saw_response = 0; ; saw_response = 1) {
 131                 struct ref *ref;
 132                 struct object_id old_oid;
 133                 char *name;
 134                 int len, name_len;
 135                 char *buffer = packet_buffer;
 136                 const char *arg;
 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(saw_response);
 144
 145                 if (!len)
 146                         break;
 147
 148                 if (len > 4 && skip_prefix(buffer, "ERR ", &arg))
 149                         die("remote error: %s", arg);
 150
 151                 if (len == GIT_SHA1_HEXSZ + strlen("shallow ") &&
 152                         skip_prefix(buffer, "shallow ", &arg)) {
 153                         if (get_oid_hex(arg, &old_oid))
 154                                 die("protocol error: expected shallow sha-1, got '%s'", arg);
 155                         if (!shallow_points)
 156                                 die("repository on the other end cannot be shallow");
 157                         oid_array_append(shallow_points, &old_oid);
 158                         continue;
 159                 }
 160
 161                 if (len < GIT_SHA1_HEXSZ + 2 || get_oid_hex(buffer, &old_oid) ||
 162                         buffer[GIT_SHA1_HEXSZ] != ' ')
 163                         die("protocol error: expected sha/ref, got '%s'", buffer);
 164                 name = buffer + GIT_SHA1_HEXSZ + 1;
 165
 166                 name_len = strlen(name);
 167                 if (len != name_len + GIT_SHA1_HEXSZ + 1) {
 168                         free(server_capabilities);
 169                         server_capabilities = xstrdup(name + name_len + 1);
 170                 }
 171
 172                 if (extra_have && !strcmp(name, ".have")) {
 173                         oid_array_append(extra_have, &old_oid);
 174                         continue;
 175                 }
 176
 177                 if (!strcmp(name, "capabilities^{}")) {
 178                         if (saw_response)
 179                                 die("protocol error: unexpected capabilities^{}");
 180                         if (got_dummy_ref_with_capabilities_declaration)
 181                                 die("protocol error: multiple capabilities^{}");
 182                         got_dummy_ref_with_capabilities_declaration = 1;
 183                         continue;
 184                 }
 185
 186                 if (!check_ref(name, flags))
 187                         continue;
 188
 189                 if (got_dummy_ref_with_capabilities_declaration)
 190                         die("protocol error: unexpected ref after capabilities^{}");
 191
 192                 ref = alloc_ref(buffer + GIT_SHA1_HEXSZ + 1);
 193                 oidcpy(&ref->old_oid, &old_oid);
 194                 *list = ref;
 195                 list = &ref->next;
 196         }
 197
 198         annotate_refs_with_symref_info(*orig_list);
 199
 200         return list;
 201 }
 202
 203 static const char *parse_feature_value(const char *feature_list, const char *feature, int *lenp)
 204 {
 205         int len;
 206
 207         if (!feature_list)
 208                 return NULL;
 209
 210         len = strlen(feature);
 211         while (*feature_list) {
 212                 const char *found = strstr(feature_list, feature);
 213                 if (!found)
 214                         return NULL;
 215                 if (feature_list == found || isspace(found[-1])) {
 216                         const char *value = found + len;
 217                         /* feature with no value (e.g., "thin-pack") */
 218                         if (!*value || isspace(*value)) {
 219                                 if (lenp)
 220                                         *lenp = 0;
 221                                 return value;
 222                         }
 223                         /* feature with a value (e.g., "agent=git/1.2.3") */
 224                         else if (*value == '=') {
 225                                 value++;
 226                                 if (lenp)
 227                                         *lenp = strcspn(value, " \t\n");
 228                                 return value;
 229                         }
 230                         /*
 231                          * otherwise we matched a substring of another feature;
 232                          * keep looking
 233                          */
 234                 }
 235                 feature_list = found + 1;
 236         }
 237         return NULL;
 238 }
 239
 240 int parse_feature_request(const char *feature_list, const char *feature)
 241 {
 242         return !!parse_feature_value(feature_list, feature, NULL);
 243 }
 244
 245 const char *server_feature_value(const char *feature, int *len)
 246 {
 247         return parse_feature_value(server_capabilities, feature, len);
 248 }
 249
 250 int server_supports(const char *feature)
 251 {
 252         return !!server_feature_value(feature, NULL);
 253 }
 254
 255 enum protocol {
 256         PROTO_LOCAL = 1,
 257         PROTO_FILE,
 258         PROTO_SSH,
 259         PROTO_GIT
 260 };
 261
 262 int url_is_local_not_ssh(const char *url)
 263 {
 264         const char *colon = strchr(url, ':');
 265         const char *slash = strchr(url, '/');
 266         return !colon || (slash && slash < colon) ||
 267                 has_dos_drive_prefix(url);
 268 }
 269
 270 static const char *prot_name(enum protocol protocol)
 271 {
 272         switch (protocol) {
 273                 case PROTO_LOCAL:
 274                 case PROTO_FILE:
 275                         return "file";
 276                 case PROTO_SSH:
 277                         return "ssh";
 278                 case PROTO_GIT:
 279                         return "git";
 280                 default:
 281                         return "unknown protocol";
 282         }
 283 }
 284
 285 static enum protocol get_protocol(const char *name)
 286 {
 287         if (!strcmp(name, "ssh"))
 288                 return PROTO_SSH;
 289         if (!strcmp(name, "git"))
 290                 return PROTO_GIT;
 291         if (!strcmp(name, "git+ssh")) /* deprecated - do not use */
 292                 return PROTO_SSH;
 293         if (!strcmp(name, "ssh+git")) /* deprecated - do not use */
 294                 return PROTO_SSH;
 295         if (!strcmp(name, "file"))
 296                 return PROTO_FILE;
 297         die("I don't handle protocol '%s'", name);
 298 }
 299
 300 static char *host_end(char **hoststart, int removebrackets)
 301 {
 302         char *host = *hoststart;
 303         char *end;
 304         char *start = strstr(host, "@[");
 305         if (start)
 306                 start++; /* Jump over '@' */
 307         else
 308                 start = host;
 309         if (start[0] == '[') {
 310                 end = strchr(start + 1, ']');
 311                 if (end) {
 312                         if (removebrackets) {
 313                                 *end = 0;
 314                                 memmove(start, start + 1, end - start);
 315                                 end++;
 316                         }
 317                 } else
 318                         end = host;
 319         } else
 320                 end = host;
 321         return end;
 322 }
 323
 324 #define STR_(s) # s
 325 #define STR(s)  STR_(s)
 326
 327 static void get_host_and_port(char **host, const char **port)
 328 {
 329         char *colon, *end;
 330         end = host_end(host, 1);
 331         colon = strchr(end, ':');
 332         if (colon) {
 333                 long portnr = strtol(colon + 1, &end, 10);
 334                 if (end != colon + 1 && *end == '\0' && 0 <= portnr && portnr < 65536) {
 335                         *colon = 0;
 336                         *port = colon + 1;
 337                 } else if (!colon[1]) {
 338                         *colon = 0;
 339                 }
 340         }
 341 }
 342
 343 static void enable_keepalive(int sockfd)
 344 {
 345         int ka = 1;
 346
 347         if (setsockopt(sockfd, SOL_SOCKET, SO_KEEPALIVE, &ka, sizeof(ka)) < 0)
 348                 fprintf(stderr, "unable to set SO_KEEPALIVE on socket: %s\n",
 349                         strerror(errno));
 350 }
 351
 352 #ifndef NO_IPV6
 353
 354 static const char *ai_name(const struct addrinfo *ai)
 355 {
 356         static char addr[NI_MAXHOST];
 357         if (getnameinfo(ai->ai_addr, ai->ai_addrlen, addr, sizeof(addr), NULL, 0,
 358                         NI_NUMERICHOST) != 0)
 359                 xsnprintf(addr, sizeof(addr), "(unknown)");
 360
 361         return addr;
 362 }
 363
 364 /*
 365  * Returns a connected socket() fd, or else die()s.
 366  */
 367 static int git_tcp_connect_sock(char *host, int flags)
 368 {
 369         struct strbuf error_message = STRBUF_INIT;
 370         int sockfd = -1;
 371         const char *port = STR(DEFAULT_GIT_PORT);
 372         struct addrinfo hints, *ai0, *ai;
 373         int gai;
 374         int cnt = 0;
 375
 376         get_host_and_port(&host, &port);
 377         if (!*port)
 378                 port = "<none>";
 379
 380         memset(&hints, 0, sizeof(hints));
 381         if (flags & CONNECT_IPV4)
 382                 hints.ai_family = AF_INET;
 383         else if (flags & CONNECT_IPV6)
 384                 hints.ai_family = AF_INET6;
 385         hints.ai_socktype = SOCK_STREAM;
 386         hints.ai_protocol = IPPROTO_TCP;
 387
 388         if (flags & CONNECT_VERBOSE)
 389                 fprintf(stderr, "Looking up %s ... ", host);
 390
 391         gai = getaddrinfo(host, port, &hints, &ai);
 392         if (gai)
 393                 die("Unable to look up %s (port %s) (%s)", host, port, gai_strerror(gai));
 394
 395         if (flags & CONNECT_VERBOSE)
 396                 fprintf(stderr, "done.\nConnecting to %s (port %s) ... ", host, port);
 397
 398         for (ai0 = ai; ai; ai = ai->ai_next, cnt++) {
 399                 sockfd = socket(ai->ai_family,
 400                                 ai->ai_socktype, ai->ai_protocol);
 401                 if ((sockfd < 0) ||
 402                     (connect(sockfd, ai->ai_addr, ai->ai_addrlen) < 0)) {
 403                         strbuf_addf(&error_message, "%s[%d: %s]: errno=%s\n",
 404                                     host, cnt, ai_name(ai), strerror(errno));
 405                         if (0 <= sockfd)
 406                                 close(sockfd);
 407                         sockfd = -1;
 408                         continue;
 409                 }
 410                 if (flags & CONNECT_VERBOSE)
 411                         fprintf(stderr, "%s ", ai_name(ai));
 412                 break;
 413         }
 414
 415         freeaddrinfo(ai0);
 416
 417         if (sockfd < 0)
 418                 die("unable to connect to %s:\n%s", host, error_message.buf);
 419
 420         enable_keepalive(sockfd);
 421
 422         if (flags & CONNECT_VERBOSE)
 423                 fprintf(stderr, "done.\n");
 424
 425         strbuf_release(&error_message);
 426
 427         return sockfd;
 428 }
 429
 430 #else /* NO_IPV6 */
 431
 432 /*
 433  * Returns a connected socket() fd, or else die()s.
 434  */
 435 static int git_tcp_connect_sock(char *host, int flags)
 436 {
 437         struct strbuf error_message = STRBUF_INIT;
 438         int sockfd = -1;
 439         const char *port = STR(DEFAULT_GIT_PORT);
 440         char *ep;
 441         struct hostent *he;
 442         struct sockaddr_in sa;
 443         char **ap;
 444         unsigned int nport;
 445         int cnt;
 446
 447         get_host_and_port(&host, &port);
 448
 449         if (flags & CONNECT_VERBOSE)
 450                 fprintf(stderr, "Looking up %s ... ", host);
 451
 452         he = gethostbyname(host);
 453         if (!he)
 454                 die("Unable to look up %s (%s)", host, hstrerror(h_errno));
 455         nport = strtoul(port, &ep, 10);
 456         if ( ep == port || *ep ) {
 457                 /* Not numeric */
 458                 struct servent *se = getservbyname(port,"tcp");
 459                 if ( !se )
 460                         die("Unknown port %s", port);
 461                 nport = se->s_port;
 462         }
 463
 464         if (flags & CONNECT_VERBOSE)
 465                 fprintf(stderr, "done.\nConnecting to %s (port %s) ... ", host, port);
 466
 467         for (cnt = 0, ap = he->h_addr_list; *ap; ap++, cnt++) {
 468                 memset(&sa, 0, sizeof sa);
 469                 sa.sin_family = he->h_addrtype;
 470                 sa.sin_port = htons(nport);
 471                 memcpy(&sa.sin_addr, *ap, he->h_length);
 472
 473                 sockfd = socket(he->h_addrtype, SOCK_STREAM, 0);
 474                 if ((sockfd < 0) ||
 475                     connect(sockfd, (struct sockaddr *)&sa, sizeof sa) < 0) {
 476                         strbuf_addf(&error_message, "%s[%d: %s]: errno=%s\n",
 477                                 host,
 478                                 cnt,
 479                                 inet_ntoa(*(struct in_addr *)&sa.sin_addr),
 480                                 strerror(errno));
 481                         if (0 <= sockfd)
 482                                 close(sockfd);
 483                         sockfd = -1;
 484                         continue;
 485                 }
 486                 if (flags & CONNECT_VERBOSE)
 487                         fprintf(stderr, "%s ",
 488                                 inet_ntoa(*(struct in_addr *)&sa.sin_addr));
 489                 break;
 490         }
 491
 492         if (sockfd < 0)
 493                 die("unable to connect to %s:\n%s", host, error_message.buf);
 494
 495         enable_keepalive(sockfd);
 496
 497         if (flags & CONNECT_VERBOSE)
 498                 fprintf(stderr, "done.\n");
 499
 500         return sockfd;
 501 }
 502
 503 #endif /* NO_IPV6 */
 504
 505
 506 static void git_tcp_connect(int fd[2], char *host, int flags)
 507 {
 508         int sockfd = git_tcp_connect_sock(host, flags);
 509
 510         fd[0] = sockfd;
 511         fd[1] = dup(sockfd);
 512 }
 513
 514
 515 static char *git_proxy_command;
 516
 517 static int git_proxy_command_options(const char *var, const char *value,
 518                 void *cb)
 519 {
 520         if (!strcmp(var, "core.gitproxy")) {
 521                 const char *for_pos;
 522                 int matchlen = -1;
 523                 int hostlen;
 524                 const char *rhost_name = cb;
 525                 int rhost_len = strlen(rhost_name);
 526
 527                 if (git_proxy_command)
 528                         return 0;
 529                 if (!value)
 530                         return config_error_nonbool(var);
 531                 /* [core]
 532                  * ;# matches www.kernel.org as well
 533                  * gitproxy = netcatter-1 for kernel.org
 534                  * gitproxy = netcatter-2 for sample.xz
 535                  * gitproxy = netcatter-default
 536                  */
 537                 for_pos = strstr(value, " for ");
 538                 if (!for_pos)
 539                         /* matches everybody */
 540                         matchlen = strlen(value);
 541                 else {
 542                         hostlen = strlen(for_pos + 5);
 543                         if (rhost_len < hostlen)
 544                                 matchlen = -1;
 545                         else if (!strncmp(for_pos + 5,
 546                                           rhost_name + rhost_len - hostlen,
 547                                           hostlen) &&
 548                                  ((rhost_len == hostlen) ||
 549                                   rhost_name[rhost_len - hostlen -1] == '.'))
 550                                 matchlen = for_pos - value;
 551                         else
 552                                 matchlen = -1;
 553                 }
 554                 if (0 <= matchlen) {
 555                         /* core.gitproxy = none for kernel.org */
 556                         if (matchlen == 4 &&
 557                             !memcmp(value, "none", 4))
 558                                 matchlen = 0;
 559                         git_proxy_command = xmemdupz(value, matchlen);
 560                 }
 561                 return 0;
 562         }
 563
 564         return git_default_config(var, value, cb);
 565 }
 566
 567 static int git_use_proxy(const char *host)
 568 {
 569         git_proxy_command = getenv("GIT_PROXY_COMMAND");
 570         git_config(git_proxy_command_options, (void*)host);
 571         return (git_proxy_command && *git_proxy_command);
 572 }
 573
 574 static struct child_process *git_proxy_connect(int fd[2], char *host)
 575 {
 576         const char *port = STR(DEFAULT_GIT_PORT);
 577         struct child_process *proxy;
 578
 579         get_host_and_port(&host, &port);
 580
 581         if (looks_like_command_line_option(host))
 582                 die("strange hostname '%s' blocked", host);
 583         if (looks_like_command_line_option(port))
 584                 die("strange port '%s' blocked", port);
 585
 586         proxy = xmalloc(sizeof(*proxy));
 587         child_process_init(proxy);
 588         argv_array_push(&proxy->args, git_proxy_command);
 589         argv_array_push(&proxy->args, host);
 590         argv_array_push(&proxy->args, port);
 591         proxy->in = -1;
 592         proxy->out = -1;
 593         if (start_command(proxy))
 594                 die("cannot start proxy %s", git_proxy_command);
 595         fd[0] = proxy->out; /* read from proxy stdout */
 596         fd[1] = proxy->in;  /* write to proxy stdin */
 597         return proxy;
 598 }
 599
 600 static char *get_port(char *host)
 601 {
 602         char *end;
 603         char *p = strchr(host, ':');
 604
 605         if (p) {
 606                 long port = strtol(p + 1, &end, 10);
 607                 if (end != p + 1 && *end == '\0' && 0 <= port && port < 65536) {
 608                         *p = '\0';
 609                         return p+1;
 610                 }
 611         }
 612
 613         return NULL;
 614 }
 615
 616 /*
 617  * Extract protocol and relevant parts from the specified connection URL.
 618  * The caller must free() the returned strings.
 619  */
 620 static enum protocol parse_connect_url(const char *url_orig, char **ret_host,
 621                                        char **ret_path)
 622 {
 623         char *url;
 624         char *host, *path;
 625         char *end;
 626         int separator = '/';
 627         enum protocol protocol = PROTO_LOCAL;
 628
 629         if (is_url(url_orig))
 630                 url = url_decode(url_orig);
 631         else
 632                 url = xstrdup(url_orig);
 633
 634         host = strstr(url, "://");
 635         if (host) {
 636                 *host = '\0';
 637                 protocol = get_protocol(url);
 638                 host += 3;
 639         } else {
 640                 host = url;
 641                 if (!url_is_local_not_ssh(url)) {
 642                         protocol = PROTO_SSH;
 643                         separator = ':';
 644                 }
 645         }
 646
 647         /*
 648          * Don't do destructive transforms as protocol code does
 649          * '[]' unwrapping in get_host_and_port()
 650          */
 651         end = host_end(&host, 0);
 652
 653         if (protocol == PROTO_LOCAL)
 654                 path = end;
 655         else if (protocol == PROTO_FILE && has_dos_drive_prefix(end))
 656                 path = end; /* "file://$(pwd)" may be "file://C:/projects/repo" */
 657         else
 658                 path = strchr(end, separator);
 659
 660         if (!path || !*path)
 661                 die("No path specified. See 'man git-pull' for valid url syntax");
 662
 663         /*
 664          * null-terminate hostname and point path to ~ for URL's like this:
 665          *    ssh://host.xz/~user/repo
 666          */
 667
 668         end = path; /* Need to \0 terminate host here */
 669         if (separator == ':')
 670                 path++; /* path starts after ':' */
 671         if (protocol == PROTO_GIT || protocol == PROTO_SSH) {
 672                 if (path[1] == '~')
 673                         path++;
 674         }
 675
 676         path = xstrdup(path);
 677         *end = '\0';
 678
 679         *ret_host = xstrdup(host);
 680         *ret_path = path;
 681         free(url);
 682         return protocol;
 683 }
 684
 685 static struct child_process no_fork = CHILD_PROCESS_INIT;
 686
 687 static const char *get_ssh_command(void)
 688 {
 689         const char *ssh;
 690
 691         if ((ssh = getenv("GIT_SSH_COMMAND")))
 692                 return ssh;
 693
 694         if (!git_config_get_string_const("core.sshcommand", &ssh))
 695                 return ssh;
 696
 697         return NULL;
 698 }
 699
 700 static int override_ssh_variant(int *port_option, int *needs_batch)
 701 {
 702         char *variant;
 703
 704         variant = xstrdup_or_null(getenv("GIT_SSH_VARIANT"));
 705         if (!variant &&
 706             git_config_get_string("ssh.variant", &variant))
 707                 return 0;
 708
 709         if (!strcmp(variant, "plink") || !strcmp(variant, "putty")) {
 710                 *port_option = 'P';
 711                 *needs_batch = 0;
 712         } else if (!strcmp(variant, "tortoiseplink")) {
 713                 *port_option = 'P';
 714                 *needs_batch = 1;
 715         } else {
 716                 *port_option = 'p';
 717                 *needs_batch = 0;
 718         }
 719         free(variant);
 720         return 1;
 721 }
 722
 723 static void handle_ssh_variant(const char *ssh_command, int is_cmdline,
 724                                int *port_option, int *needs_batch)
 725 {
 726         const char *variant;
 727         char *p = NULL;
 728
 729         if (override_ssh_variant(port_option, needs_batch))
 730                 return;
 731
 732         if (!is_cmdline) {
 733                 p = xstrdup(ssh_command);
 734                 variant = basename(p);
 735         } else {
 736                 const char **ssh_argv;
 737
 738                 p = xstrdup(ssh_command);
 739                 if (split_cmdline(p, &ssh_argv) > 0) {
 740                         variant = basename((char *)ssh_argv[0]);
 741                         /*
 742                          * At this point, variant points into the buffer
 743                          * referenced by p, hence we do not need ssh_argv
 744                          * any longer.
 745                          */
 746                         free(ssh_argv);
 747                 } else {
 748                         free(p);
 749                         return;
 750                 }
 751         }
 752
 753         if (!strcasecmp(variant, "plink") ||
 754             !strcasecmp(variant, "plink.exe"))
 755                 *port_option = 'P';
 756         else if (!strcasecmp(variant, "tortoiseplink") ||
 757                  !strcasecmp(variant, "tortoiseplink.exe")) {
 758                 *port_option = 'P';
 759                 *needs_batch = 1;
 760         }
 761         free(p);
 762 }
 763
 764 /*
 765  * This returns a dummy child_process if the transport protocol does not
 766  * need fork(2), or a struct child_process object if it does.  Once done,
 767  * finish the connection with finish_connect() with the value returned from
 768  * this function (it is safe to call finish_connect() with NULL to support
 769  * the former case).
 770  *
 771  * If it returns, the connect is successful; it just dies on errors (this
 772  * will hopefully be changed in a libification effort, to return NULL when
 773  * the connection failed).
 774  */
 775 struct child_process *git_connect(int fd[2], const char *url,
 776                                   const char *prog, int flags)
 777 {
 778         char *hostandport, *path;
 779         struct child_process *conn = &no_fork;
 780         enum protocol protocol;
 781         struct strbuf cmd = STRBUF_INIT;
 782
 783         /* Without this we cannot rely on waitpid() to tell
 784          * what happened to our children.
 785          */
 786         signal(SIGCHLD, SIG_DFL);
 787
 788         protocol = parse_connect_url(url, &hostandport, &path);
 789         if ((flags & CONNECT_DIAG_URL) && (protocol != PROTO_SSH)) {
 790                 printf("Diag: url=%s\n", url ? url : "NULL");
 791                 printf("Diag: protocol=%s\n", prot_name(protocol));
 792                 printf("Diag: hostandport=%s\n", hostandport ? hostandport : "NULL");
 793                 printf("Diag: path=%s\n", path ? path : "NULL");
 794                 conn = NULL;
 795         } else if (protocol == PROTO_GIT) {
 796                 /*
 797                  * Set up virtual host information based on where we will
 798                  * connect, unless the user has overridden us in
 799                  * the environment.
 800                  */
 801                 char *target_host = getenv("GIT_OVERRIDE_VIRTUAL_HOST");
 802                 if (target_host)
 803                         target_host = xstrdup(target_host);
 804                 else
 805                         target_host = xstrdup(hostandport);
 806
 807                 transport_check_allowed("git");
 808
 809                 /* These underlying connection commands die() if they
 810                  * cannot connect.
 811                  */
 812                 if (git_use_proxy(hostandport))
 813                         conn = git_proxy_connect(fd, hostandport);
 814                 else
 815                         git_tcp_connect(fd, hostandport, flags);
 816                 /*
 817                  * Separate original protocol components prog and path
 818                  * from extended host header with a NUL byte.
 819                  *
 820                  * Note: Do not add any other headers here!  Doing so
 821                  * will cause older git-daemon servers to crash.
 822                  */
 823                 packet_write_fmt(fd[1],
 824                              "%s %s%chost=%s%c",
 825                              prog, path, 0,
 826                              target_host, 0);
 827                 free(target_host);
 828         } else {
 829                 conn = xmalloc(sizeof(*conn));
 830                 child_process_init(conn);
 831
 832                 if (looks_like_command_line_option(path))
 833                         die("strange pathname '%s' blocked", path);
 834
 835                 strbuf_addstr(&cmd, prog);
 836                 strbuf_addch(&cmd, ' ');
 837                 sq_quote_buf(&cmd, path);
 838
 839                 /* remove repo-local variables from the environment */
 840                 conn->env = local_repo_env;
 841                 conn->use_shell = 1;
 842                 conn->in = conn->out = -1;
 843                 if (protocol == PROTO_SSH) {
 844                         const char *ssh;
 845                         int needs_batch = 0;
 846                         int port_option = 'p';
 847                         char *ssh_host = hostandport;
 848                         const char *port = NULL;
 849                         transport_check_allowed("ssh");
 850                         get_host_and_port(&ssh_host, &port);
 851
 852                         if (!port)
 853                                 port = get_port(ssh_host);
 854
 855                         if (flags & CONNECT_DIAG_URL) {
 856                                 printf("Diag: url=%s\n", url ? url : "NULL");
 857                                 printf("Diag: protocol=%s\n", prot_name(protocol));
 858                                 printf("Diag: userandhost=%s\n", ssh_host ? ssh_host : "NULL");
 859                                 printf("Diag: port=%s\n", port ? port : "NONE");
 860                                 printf("Diag: path=%s\n", path ? path : "NULL");
 861
 862                                 free(hostandport);
 863                                 free(path);
 864                                 free(conn);
 865                                 return NULL;
 866                         }
 867
 868                         if (looks_like_command_line_option(ssh_host))
 869                                 die("strange hostname '%s' blocked", ssh_host);
 870
 871                         ssh = get_ssh_command();
 872                         if (ssh)
 873                                 handle_ssh_variant(ssh, 1, &port_option,
 874                                                    &needs_batch);
 875                         else {
 876                                 /*
 877                                  * GIT_SSH is the no-shell version of
 878                                  * GIT_SSH_COMMAND (and must remain so for
 879                                  * historical compatibility).
 880                                  */
 881                                 conn->use_shell = 0;
 882
 883                                 ssh = getenv("GIT_SSH");
 884                                 if (!ssh)
 885                                         ssh = "ssh";
 886                                 else
 887                                         handle_ssh_variant(ssh, 0,
 888                                                            &port_option,
 889                                                            &needs_batch);
 890                         }
 891
 892                         argv_array_push(&conn->args, ssh);
 893                         if (flags & CONNECT_IPV4)
 894                                 argv_array_push(&conn->args, "-4");
 895                         else if (flags & CONNECT_IPV6)
 896                                 argv_array_push(&conn->args, "-6");
 897                         if (needs_batch)
 898                                 argv_array_push(&conn->args, "-batch");
 899                         if (port) {
 900                                 argv_array_pushf(&conn->args,
 901                                                  "-%c", port_option);
 902                                 argv_array_push(&conn->args, port);
 903                         }
 904                         argv_array_push(&conn->args, ssh_host);
 905                 } else {
 906                         transport_check_allowed("file");
 907                 }
 908                 argv_array_push(&conn->args, cmd.buf);
 909
 910                 if (start_command(conn))
 911                         die("unable to fork");
 912
 913                 fd[0] = conn->out; /* read from child's stdout */
 914                 fd[1] = conn->in;  /* write to child's stdin */
 915                 strbuf_release(&cmd);
 916         }
 917         free(hostandport);
 918         free(path);
 919         return conn;
 920 }
 921
 922 int git_connection_is_socket(struct child_process *conn)
 923 {
 924         return conn == &no_fork;
 925 }
 926
 927 int finish_connect(struct child_process *conn)
 928 {
 929         int code;
 930         if (!conn || git_connection_is_socket(conn))
 931                 return 0;
 932
 933         code = finish_command(conn);
 934         free(conn);
 935         return code;
 936 }