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 #include "strbuf.h"
  15
  16 static char *server_capabilities;
  17 static const char *parse_feature_value(const char *, const char *, int *);
  18
  19 static int check_ref(const char *name, unsigned int flags)
  20 {
  21         if (!flags)
  22                 return 1;
  23
  24         if (!skip_prefix(name, "refs/", &name))
  25                 return 0;
  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) && starts_with(name, "heads/"))
  33                 return 1;
  34
  35         /* REF_TAGS means that we want tags */
  36         if ((flags & REF_TAGS) && starts_with(name, "tags/"))
  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, flags);
  46 }
  47
  48 static void die_initial_contact(int unexpected)
  49 {
  50         if (unexpected)
  51                 die(_("The remote end hung up upon initial contact"));
  52         else
  53                 die(_("Could not read from remote repository.\n\n"
  54                       "Please make sure you have the correct access rights\n"
  55                       "and the repository exists."));
  56 }
  57
  58 static void parse_one_symref_info(struct string_list *symref, const char *val, int len)
  59 {
  60         char *sym, *target;
  61         struct string_list_item *item;
  62
  63         if (!len)
  64                 return; /* just "symref" */
  65         /* e.g. "symref=HEAD:refs/heads/master" */
  66         sym = xmemdupz(val, len);
  67         target = strchr(sym, ':');
  68         if (!target)
  69                 /* just "symref=something" */
  70                 goto reject;
  71         *(target++) = '\0';
  72         if (check_refname_format(sym, REFNAME_ALLOW_ONELEVEL) ||
  73             check_refname_format(target, REFNAME_ALLOW_ONELEVEL))
  74                 /* "symref=bogus:pair */
  75                 goto reject;
  76         item = string_list_append_nodup(symref, sym);
  77         item->util = target;
  78         return;
  79 reject:
  80         free(sym);
  81         return;
  82 }
  83
  84 static void annotate_refs_with_symref_info(struct ref *ref)
  85 {
  86         struct string_list symref = STRING_LIST_INIT_DUP;
  87         const char *feature_list = server_capabilities;
  88
  89         while (feature_list) {
  90                 int len;
  91                 const char *val;
  92
  93                 val = parse_feature_value(feature_list, "symref", &len);
  94                 if (!val)
  95                         break;
  96                 parse_one_symref_info(&symref, val, len);
  97                 feature_list = val + 1;
  98         }
  99         string_list_sort(&symref);
 100
 101         for (; ref; ref = ref->next) {
 102                 struct string_list_item *item;
 103                 item = string_list_lookup(&symref, ref->name);
 104                 if (!item)
 105                         continue;
 106                 ref->symref = xstrdup((char *)item->util);
 107         }
 108         string_list_clear(&symref, 0);
 109 }
 110
 111 /*
 112  * Read one line of a server's ref advertisement into packet_buffer.
 113  */
 114 static int read_remote_ref(int in, char **src_buf, size_t *src_len,
 115                            int *responded)
 116 {
 117         int len = packet_read(in, src_buf, src_len,
 118                               packet_buffer, sizeof(packet_buffer),
 119                               PACKET_READ_GENTLE_ON_EOF |
 120                               PACKET_READ_CHOMP_NEWLINE);
 121         const char *arg;
 122         if (len < 0)
 123                 die_initial_contact(*responded);
 124         if (len > 4 && skip_prefix(packet_buffer, "ERR ", &arg))
 125                 die("remote error: %s", arg);
 126
 127         *responded = 1;
 128
 129         return len;
 130 }
 131
 132 #define EXPECTING_FIRST_REF 0
 133 #define EXPECTING_REF 1
 134 #define EXPECTING_SHALLOW 2
 135
 136 static void process_capabilities(int *len)
 137 {
 138         int nul_location = strlen(packet_buffer);
 139         if (nul_location == *len)
 140                 return;
 141         server_capabilities = xstrdup(packet_buffer + nul_location + 1);
 142         *len = nul_location;
 143 }
 144
 145 static int process_dummy_ref(void)
 146 {
 147         struct object_id oid;
 148         const char *name;
 149
 150         if (parse_oid_hex(packet_buffer, &oid, &name))
 151                 return 0;
 152         if (*name != ' ')
 153                 return 0;
 154         name++;
 155
 156         return !oidcmp(&null_oid, &oid) && !strcmp(name, "capabilities^{}");
 157 }
 158
 159 static void check_no_capabilities(int len)
 160 {
 161         if (strlen(packet_buffer) != len)
 162                 warning("Ignoring capabilities after first line '%s'",
 163                         packet_buffer + strlen(packet_buffer));
 164 }
 165
 166 static int process_ref(int len, struct ref ***list, unsigned int flags,
 167                        struct oid_array *extra_have)
 168 {
 169         struct object_id old_oid;
 170         const char *name;
 171
 172         if (parse_oid_hex(packet_buffer, &old_oid, &name))
 173                 return 0;
 174         if (*name != ' ')
 175                 return 0;
 176         name++;
 177
 178         if (extra_have && !strcmp(name, ".have")) {
 179                 oid_array_append(extra_have, &old_oid);
 180         } else if (!strcmp(name, "capabilities^{}")) {
 181                 die("protocol error: unexpected capabilities^{}");
 182         } else if (check_ref(name, flags)) {
 183                 struct ref *ref = alloc_ref(name);
 184                 oidcpy(&ref->old_oid, &old_oid);
 185                 **list = ref;
 186                 *list = &ref->next;
 187         }
 188         check_no_capabilities(len);
 189         return 1;
 190 }
 191
 192 static int process_shallow(int len, struct oid_array *shallow_points)
 193 {
 194         const char *arg;
 195         struct object_id old_oid;
 196
 197         if (!skip_prefix(packet_buffer, "shallow ", &arg))
 198                 return 0;
 199
 200         if (get_oid_hex(arg, &old_oid))
 201                 die("protocol error: expected shallow sha-1, got '%s'", arg);
 202         if (!shallow_points)
 203                 die("repository on the other end cannot be shallow");
 204         oid_array_append(shallow_points, &old_oid);
 205         check_no_capabilities(len);
 206         return 1;
 207 }
 208
 209 /*
 210  * Read all the refs from the other end
 211  */
 212 struct ref **get_remote_heads(int in, char *src_buf, size_t src_len,
 213                               struct ref **list, unsigned int flags,
 214                               struct oid_array *extra_have,
 215                               struct oid_array *shallow_points)
 216 {
 217         struct ref **orig_list = list;
 218
 219         /*
 220          * A hang-up after seeing some response from the other end
 221          * means that it is unexpected, as we know the other end is
 222          * willing to talk to us.  A hang-up before seeing any
 223          * response does not necessarily mean an ACL problem, though.
 224          */
 225         int responded = 0;
 226         int len;
 227         int state = EXPECTING_FIRST_REF;
 228
 229         *list = NULL;
 230
 231         while ((len = read_remote_ref(in, &src_buf, &src_len, &responded))) {
 232                 switch (state) {
 233                 case EXPECTING_FIRST_REF:
 234                         process_capabilities(&len);
 235                         if (process_dummy_ref()) {
 236                                 state = EXPECTING_SHALLOW;
 237                                 break;
 238                         }
 239                         state = EXPECTING_REF;
 240                         /* fallthrough */
 241                 case EXPECTING_REF:
 242                         if (process_ref(len, &list, flags, extra_have))
 243                                 break;
 244                         state = EXPECTING_SHALLOW;
 245                         /* fallthrough */
 246                 case EXPECTING_SHALLOW:
 247                         if (process_shallow(len, shallow_points))
 248                                 break;
 249                         die("protocol error: unexpected '%s'", packet_buffer);
 250                 default:
 251                         die("unexpected state %d", state);
 252                 }
 253         }
 254
 255         annotate_refs_with_symref_info(*orig_list);
 256
 257         return list;
 258 }
 259
 260 static const char *parse_feature_value(const char *feature_list, const char *feature, int *lenp)
 261 {
 262         int len;
 263
 264         if (!feature_list)
 265                 return NULL;
 266
 267         len = strlen(feature);
 268         while (*feature_list) {
 269                 const char *found = strstr(feature_list, feature);
 270                 if (!found)
 271                         return NULL;
 272                 if (feature_list == found || isspace(found[-1])) {
 273                         const char *value = found + len;
 274                         /* feature with no value (e.g., "thin-pack") */
 275                         if (!*value || isspace(*value)) {
 276                                 if (lenp)
 277                                         *lenp = 0;
 278                                 return value;
 279                         }
 280                         /* feature with a value (e.g., "agent=git/1.2.3") */
 281                         else if (*value == '=') {
 282                                 value++;
 283                                 if (lenp)
 284                                         *lenp = strcspn(value, " \t\n");
 285                                 return value;
 286                         }
 287                         /*
 288                          * otherwise we matched a substring of another feature;
 289                          * keep looking
 290                          */
 291                 }
 292                 feature_list = found + 1;
 293         }
 294         return NULL;
 295 }
 296
 297 int parse_feature_request(const char *feature_list, const char *feature)
 298 {
 299         return !!parse_feature_value(feature_list, feature, NULL);
 300 }
 301
 302 const char *server_feature_value(const char *feature, int *len)
 303 {
 304         return parse_feature_value(server_capabilities, feature, len);
 305 }
 306
 307 int server_supports(const char *feature)
 308 {
 309         return !!server_feature_value(feature, NULL);
 310 }
 311
 312 enum protocol {
 313         PROTO_LOCAL = 1,
 314         PROTO_FILE,
 315         PROTO_SSH,
 316         PROTO_GIT
 317 };
 318
 319 int url_is_local_not_ssh(const char *url)
 320 {
 321         const char *colon = strchr(url, ':');
 322         const char *slash = strchr(url, '/');
 323         return !colon || (slash && slash < colon) ||
 324                 has_dos_drive_prefix(url);
 325 }
 326
 327 static const char *prot_name(enum protocol protocol)
 328 {
 329         switch (protocol) {
 330                 case PROTO_LOCAL:
 331                 case PROTO_FILE:
 332                         return "file";
 333                 case PROTO_SSH:
 334                         return "ssh";
 335                 case PROTO_GIT:
 336                         return "git";
 337                 default:
 338                         return "unknown protocol";
 339         }
 340 }
 341
 342 static enum protocol get_protocol(const char *name)
 343 {
 344         if (!strcmp(name, "ssh"))
 345                 return PROTO_SSH;
 346         if (!strcmp(name, "git"))
 347                 return PROTO_GIT;
 348         if (!strcmp(name, "git+ssh")) /* deprecated - do not use */
 349                 return PROTO_SSH;
 350         if (!strcmp(name, "ssh+git")) /* deprecated - do not use */
 351                 return PROTO_SSH;
 352         if (!strcmp(name, "file"))
 353                 return PROTO_FILE;
 354         die("I don't handle protocol '%s'", name);
 355 }
 356
 357 static char *host_end(char **hoststart, int removebrackets)
 358 {
 359         char *host = *hoststart;
 360         char *end;
 361         char *start = strstr(host, "@[");
 362         if (start)
 363                 start++; /* Jump over '@' */
 364         else
 365                 start = host;
 366         if (start[0] == '[') {
 367                 end = strchr(start + 1, ']');
 368                 if (end) {
 369                         if (removebrackets) {
 370                                 *end = 0;
 371                                 memmove(start, start + 1, end - start);
 372                                 end++;
 373                         }
 374                 } else
 375                         end = host;
 376         } else
 377                 end = host;
 378         return end;
 379 }
 380
 381 #define STR_(s) # s
 382 #define STR(s)  STR_(s)
 383
 384 static void get_host_and_port(char **host, const char **port)
 385 {
 386         char *colon, *end;
 387         end = host_end(host, 1);
 388         colon = strchr(end, ':');
 389         if (colon) {
 390                 long portnr = strtol(colon + 1, &end, 10);
 391                 if (end != colon + 1 && *end == '\0' && 0 <= portnr && portnr < 65536) {
 392                         *colon = 0;
 393                         *port = colon + 1;
 394                 } else if (!colon[1]) {
 395                         *colon = 0;
 396                 }
 397         }
 398 }
 399
 400 static void enable_keepalive(int sockfd)
 401 {
 402         int ka = 1;
 403
 404         if (setsockopt(sockfd, SOL_SOCKET, SO_KEEPALIVE, &ka, sizeof(ka)) < 0)
 405                 fprintf(stderr, "unable to set SO_KEEPALIVE on socket: %s\n",
 406                         strerror(errno));
 407 }
 408
 409 #ifndef NO_IPV6
 410
 411 static const char *ai_name(const struct addrinfo *ai)
 412 {
 413         static char addr[NI_MAXHOST];
 414         if (getnameinfo(ai->ai_addr, ai->ai_addrlen, addr, sizeof(addr), NULL, 0,
 415                         NI_NUMERICHOST) != 0)
 416                 xsnprintf(addr, sizeof(addr), "(unknown)");
 417
 418         return addr;
 419 }
 420
 421 /*
 422  * Returns a connected socket() fd, or else die()s.
 423  */
 424 static int git_tcp_connect_sock(char *host, int flags)
 425 {
 426         struct strbuf error_message = STRBUF_INIT;
 427         int sockfd = -1;
 428         const char *port = STR(DEFAULT_GIT_PORT);
 429         struct addrinfo hints, *ai0, *ai;
 430         int gai;
 431         int cnt = 0;
 432
 433         get_host_and_port(&host, &port);
 434         if (!*port)
 435                 port = "<none>";
 436
 437         memset(&hints, 0, sizeof(hints));
 438         if (flags & CONNECT_IPV4)
 439                 hints.ai_family = AF_INET;
 440         else if (flags & CONNECT_IPV6)
 441                 hints.ai_family = AF_INET6;
 442         hints.ai_socktype = SOCK_STREAM;
 443         hints.ai_protocol = IPPROTO_TCP;
 444
 445         if (flags & CONNECT_VERBOSE)
 446                 fprintf(stderr, "Looking up %s ... ", host);
 447
 448         gai = getaddrinfo(host, port, &hints, &ai);
 449         if (gai)
 450                 die("Unable to look up %s (port %s) (%s)", host, port, gai_strerror(gai));
 451
 452         if (flags & CONNECT_VERBOSE)
 453                 fprintf(stderr, "done.\nConnecting to %s (port %s) ... ", host, port);
 454
 455         for (ai0 = ai; ai; ai = ai->ai_next, cnt++) {
 456                 sockfd = socket(ai->ai_family,
 457                                 ai->ai_socktype, ai->ai_protocol);
 458                 if ((sockfd < 0) ||
 459                     (connect(sockfd, ai->ai_addr, ai->ai_addrlen) < 0)) {
 460                         strbuf_addf(&error_message, "%s[%d: %s]: errno=%s\n",
 461                                     host, cnt, ai_name(ai), strerror(errno));
 462                         if (0 <= sockfd)
 463                                 close(sockfd);
 464                         sockfd = -1;
 465                         continue;
 466                 }
 467                 if (flags & CONNECT_VERBOSE)
 468                         fprintf(stderr, "%s ", ai_name(ai));
 469                 break;
 470         }
 471
 472         freeaddrinfo(ai0);
 473
 474         if (sockfd < 0)
 475                 die("unable to connect to %s:\n%s", host, error_message.buf);
 476
 477         enable_keepalive(sockfd);
 478
 479         if (flags & CONNECT_VERBOSE)
 480                 fprintf(stderr, "done.\n");
 481
 482         strbuf_release(&error_message);
 483
 484         return sockfd;
 485 }
 486
 487 #else /* NO_IPV6 */
 488
 489 /*
 490  * Returns a connected socket() fd, or else die()s.
 491  */
 492 static int git_tcp_connect_sock(char *host, int flags)
 493 {
 494         struct strbuf error_message = STRBUF_INIT;
 495         int sockfd = -1;
 496         const char *port = STR(DEFAULT_GIT_PORT);
 497         char *ep;
 498         struct hostent *he;
 499         struct sockaddr_in sa;
 500         char **ap;
 501         unsigned int nport;
 502         int cnt;
 503
 504         get_host_and_port(&host, &port);
 505
 506         if (flags & CONNECT_VERBOSE)
 507                 fprintf(stderr, "Looking up %s ... ", host);
 508
 509         he = gethostbyname(host);
 510         if (!he)
 511                 die("Unable to look up %s (%s)", host, hstrerror(h_errno));
 512         nport = strtoul(port, &ep, 10);
 513         if ( ep == port || *ep ) {
 514                 /* Not numeric */
 515                 struct servent *se = getservbyname(port,"tcp");
 516                 if ( !se )
 517                         die("Unknown port %s", port);
 518                 nport = se->s_port;
 519         }
 520
 521         if (flags & CONNECT_VERBOSE)
 522                 fprintf(stderr, "done.\nConnecting to %s (port %s) ... ", host, port);
 523
 524         for (cnt = 0, ap = he->h_addr_list; *ap; ap++, cnt++) {
 525                 memset(&sa, 0, sizeof sa);
 526                 sa.sin_family = he->h_addrtype;
 527                 sa.sin_port = htons(nport);
 528                 memcpy(&sa.sin_addr, *ap, he->h_length);
 529
 530                 sockfd = socket(he->h_addrtype, SOCK_STREAM, 0);
 531                 if ((sockfd < 0) ||
 532                     connect(sockfd, (struct sockaddr *)&sa, sizeof sa) < 0) {
 533                         strbuf_addf(&error_message, "%s[%d: %s]: errno=%s\n",
 534                                 host,
 535                                 cnt,
 536                                 inet_ntoa(*(struct in_addr *)&sa.sin_addr),
 537                                 strerror(errno));
 538                         if (0 <= sockfd)
 539                                 close(sockfd);
 540                         sockfd = -1;
 541                         continue;
 542                 }
 543                 if (flags & CONNECT_VERBOSE)
 544                         fprintf(stderr, "%s ",
 545                                 inet_ntoa(*(struct in_addr *)&sa.sin_addr));
 546                 break;
 547         }
 548
 549         if (sockfd < 0)
 550                 die("unable to connect to %s:\n%s", host, error_message.buf);
 551
 552         enable_keepalive(sockfd);
 553
 554         if (flags & CONNECT_VERBOSE)
 555                 fprintf(stderr, "done.\n");
 556
 557         return sockfd;
 558 }
 559
 560 #endif /* NO_IPV6 */
 561
 562
 563 static void git_tcp_connect(int fd[2], char *host, int flags)
 564 {
 565         int sockfd = git_tcp_connect_sock(host, flags);
 566
 567         fd[0] = sockfd;
 568         fd[1] = dup(sockfd);
 569 }
 570
 571
 572 static char *git_proxy_command;
 573
 574 static int git_proxy_command_options(const char *var, const char *value,
 575                 void *cb)
 576 {
 577         if (!strcmp(var, "core.gitproxy")) {
 578                 const char *for_pos;
 579                 int matchlen = -1;
 580                 int hostlen;
 581                 const char *rhost_name = cb;
 582                 int rhost_len = strlen(rhost_name);
 583
 584                 if (git_proxy_command)
 585                         return 0;
 586                 if (!value)
 587                         return config_error_nonbool(var);
 588                 /* [core]
 589                  * ;# matches www.kernel.org as well
 590                  * gitproxy = netcatter-1 for kernel.org
 591                  * gitproxy = netcatter-2 for sample.xz
 592                  * gitproxy = netcatter-default
 593                  */
 594                 for_pos = strstr(value, " for ");
 595                 if (!for_pos)
 596                         /* matches everybody */
 597                         matchlen = strlen(value);
 598                 else {
 599                         hostlen = strlen(for_pos + 5);
 600                         if (rhost_len < hostlen)
 601                                 matchlen = -1;
 602                         else if (!strncmp(for_pos + 5,
 603                                           rhost_name + rhost_len - hostlen,
 604                                           hostlen) &&
 605                                  ((rhost_len == hostlen) ||
 606                                   rhost_name[rhost_len - hostlen -1] == '.'))
 607                                 matchlen = for_pos - value;
 608                         else
 609                                 matchlen = -1;
 610                 }
 611                 if (0 <= matchlen) {
 612                         /* core.gitproxy = none for kernel.org */
 613                         if (matchlen == 4 &&
 614                             !memcmp(value, "none", 4))
 615                                 matchlen = 0;
 616                         git_proxy_command = xmemdupz(value, matchlen);
 617                 }
 618                 return 0;
 619         }
 620
 621         return git_default_config(var, value, cb);
 622 }
 623
 624 static int git_use_proxy(const char *host)
 625 {
 626         git_proxy_command = getenv("GIT_PROXY_COMMAND");
 627         git_config(git_proxy_command_options, (void*)host);
 628         return (git_proxy_command && *git_proxy_command);
 629 }
 630
 631 static struct child_process *git_proxy_connect(int fd[2], char *host)
 632 {
 633         const char *port = STR(DEFAULT_GIT_PORT);
 634         struct child_process *proxy;
 635
 636         get_host_and_port(&host, &port);
 637
 638         if (looks_like_command_line_option(host))
 639                 die("strange hostname '%s' blocked", host);
 640         if (looks_like_command_line_option(port))
 641                 die("strange port '%s' blocked", port);
 642
 643         proxy = xmalloc(sizeof(*proxy));
 644         child_process_init(proxy);
 645         argv_array_push(&proxy->args, git_proxy_command);
 646         argv_array_push(&proxy->args, host);
 647         argv_array_push(&proxy->args, port);
 648         proxy->in = -1;
 649         proxy->out = -1;
 650         if (start_command(proxy))
 651                 die("cannot start proxy %s", git_proxy_command);
 652         fd[0] = proxy->out; /* read from proxy stdout */
 653         fd[1] = proxy->in;  /* write to proxy stdin */
 654         return proxy;
 655 }
 656
 657 static char *get_port(char *host)
 658 {
 659         char *end;
 660         char *p = strchr(host, ':');
 661
 662         if (p) {
 663                 long port = strtol(p + 1, &end, 10);
 664                 if (end != p + 1 && *end == '\0' && 0 <= port && port < 65536) {
 665                         *p = '\0';
 666                         return p+1;
 667                 }
 668         }
 669
 670         return NULL;
 671 }
 672
 673 /*
 674  * Extract protocol and relevant parts from the specified connection URL.
 675  * The caller must free() the returned strings.
 676  */
 677 static enum protocol parse_connect_url(const char *url_orig, char **ret_host,
 678                                        char **ret_path)
 679 {
 680         char *url;
 681         char *host, *path;
 682         char *end;
 683         int separator = '/';
 684         enum protocol protocol = PROTO_LOCAL;
 685
 686         if (is_url(url_orig))
 687                 url = url_decode(url_orig);
 688         else
 689                 url = xstrdup(url_orig);
 690
 691         host = strstr(url, "://");
 692         if (host) {
 693                 *host = '\0';
 694                 protocol = get_protocol(url);
 695                 host += 3;
 696         } else {
 697                 host = url;
 698                 if (!url_is_local_not_ssh(url)) {
 699                         protocol = PROTO_SSH;
 700                         separator = ':';
 701                 }
 702         }
 703
 704         /*
 705          * Don't do destructive transforms as protocol code does
 706          * '[]' unwrapping in get_host_and_port()
 707          */
 708         end = host_end(&host, 0);
 709
 710         if (protocol == PROTO_LOCAL)
 711                 path = end;
 712         else if (protocol == PROTO_FILE && has_dos_drive_prefix(end))
 713                 path = end; /* "file://$(pwd)" may be "file://C:/projects/repo" */
 714         else
 715                 path = strchr(end, separator);
 716
 717         if (!path || !*path)
 718                 die("No path specified. See 'man git-pull' for valid url syntax");
 719
 720         /*
 721          * null-terminate hostname and point path to ~ for URL's like this:
 722          *    ssh://host.xz/~user/repo
 723          */
 724
 725         end = path; /* Need to \0 terminate host here */
 726         if (separator == ':')
 727                 path++; /* path starts after ':' */
 728         if (protocol == PROTO_GIT || protocol == PROTO_SSH) {
 729                 if (path[1] == '~')
 730                         path++;
 731         }
 732
 733         path = xstrdup(path);
 734         *end = '\0';
 735
 736         *ret_host = xstrdup(host);
 737         *ret_path = path;
 738         free(url);
 739         return protocol;
 740 }
 741
 742 static struct child_process no_fork = CHILD_PROCESS_INIT;
 743
 744 static const char *get_ssh_command(void)
 745 {
 746         const char *ssh;
 747
 748         if ((ssh = getenv("GIT_SSH_COMMAND")))
 749                 return ssh;
 750
 751         if (!git_config_get_string_const("core.sshcommand", &ssh))
 752                 return ssh;
 753
 754         return NULL;
 755 }
 756
 757 static int override_ssh_variant(int *port_option, int *needs_batch)
 758 {
 759         char *variant;
 760
 761         variant = xstrdup_or_null(getenv("GIT_SSH_VARIANT"));
 762         if (!variant &&
 763             git_config_get_string("ssh.variant", &variant))
 764                 return 0;
 765
 766         if (!strcmp(variant, "plink") || !strcmp(variant, "putty")) {
 767                 *port_option = 'P';
 768                 *needs_batch = 0;
 769         } else if (!strcmp(variant, "tortoiseplink")) {
 770                 *port_option = 'P';
 771                 *needs_batch = 1;
 772         } else {
 773                 *port_option = 'p';
 774                 *needs_batch = 0;
 775         }
 776         free(variant);
 777         return 1;
 778 }
 779
 780 static void handle_ssh_variant(const char *ssh_command, int is_cmdline,
 781                                int *port_option, int *needs_batch)
 782 {
 783         const char *variant;
 784         char *p = NULL;
 785
 786         if (override_ssh_variant(port_option, needs_batch))
 787                 return;
 788
 789         if (!is_cmdline) {
 790                 p = xstrdup(ssh_command);
 791                 variant = basename(p);
 792         } else {
 793                 const char **ssh_argv;
 794
 795                 p = xstrdup(ssh_command);
 796                 if (split_cmdline(p, &ssh_argv) > 0) {
 797                         variant = basename((char *)ssh_argv[0]);
 798                         /*
 799                          * At this point, variant points into the buffer
 800                          * referenced by p, hence we do not need ssh_argv
 801                          * any longer.
 802                          */
 803                         free(ssh_argv);
 804                 } else {
 805                         free(p);
 806                         return;
 807                 }
 808         }
 809
 810         if (!strcasecmp(variant, "plink") ||
 811             !strcasecmp(variant, "plink.exe"))
 812                 *port_option = 'P';
 813         else if (!strcasecmp(variant, "tortoiseplink") ||
 814                  !strcasecmp(variant, "tortoiseplink.exe")) {
 815                 *port_option = 'P';
 816                 *needs_batch = 1;
 817         }
 818         free(p);
 819 }
 820
 821 /*
 822  * This returns a dummy child_process if the transport protocol does not
 823  * need fork(2), or a struct child_process object if it does.  Once done,
 824  * finish the connection with finish_connect() with the value returned from
 825  * this function (it is safe to call finish_connect() with NULL to support
 826  * the former case).
 827  *
 828  * If it returns, the connect is successful; it just dies on errors (this
 829  * will hopefully be changed in a libification effort, to return NULL when
 830  * the connection failed).
 831  */
 832 struct child_process *git_connect(int fd[2], const char *url,
 833                                   const char *prog, int flags)
 834 {
 835         char *hostandport, *path;
 836         struct child_process *conn = &no_fork;
 837         enum protocol protocol;
 838
 839         /* Without this we cannot rely on waitpid() to tell
 840          * what happened to our children.
 841          */
 842         signal(SIGCHLD, SIG_DFL);
 843
 844         protocol = parse_connect_url(url, &hostandport, &path);
 845         if ((flags & CONNECT_DIAG_URL) && (protocol != PROTO_SSH)) {
 846                 printf("Diag: url=%s\n", url ? url : "NULL");
 847                 printf("Diag: protocol=%s\n", prot_name(protocol));
 848                 printf("Diag: hostandport=%s\n", hostandport ? hostandport : "NULL");
 849                 printf("Diag: path=%s\n", path ? path : "NULL");
 850                 conn = NULL;
 851         } else if (protocol == PROTO_GIT) {
 852                 /*
 853                  * Set up virtual host information based on where we will
 854                  * connect, unless the user has overridden us in
 855                  * the environment.
 856                  */
 857                 char *target_host = getenv("GIT_OVERRIDE_VIRTUAL_HOST");
 858                 if (target_host)
 859                         target_host = xstrdup(target_host);
 860                 else
 861                         target_host = xstrdup(hostandport);
 862
 863                 transport_check_allowed("git");
 864
 865                 /* These underlying connection commands die() if they
 866                  * cannot connect.
 867                  */
 868                 if (git_use_proxy(hostandport))
 869                         conn = git_proxy_connect(fd, hostandport);
 870                 else
 871                         git_tcp_connect(fd, hostandport, flags);
 872                 /*
 873                  * Separate original protocol components prog and path
 874                  * from extended host header with a NUL byte.
 875                  *
 876                  * Note: Do not add any other headers here!  Doing so
 877                  * will cause older git-daemon servers to crash.
 878                  */
 879                 packet_write_fmt(fd[1],
 880                              "%s %s%chost=%s%c",
 881                              prog, path, 0,
 882                              target_host, 0);
 883                 free(target_host);
 884         } else {
 885                 struct strbuf cmd = STRBUF_INIT;
 886
 887                 conn = xmalloc(sizeof(*conn));
 888                 child_process_init(conn);
 889
 890                 if (looks_like_command_line_option(path))
 891                         die("strange pathname '%s' blocked", path);
 892
 893                 strbuf_addstr(&cmd, prog);
 894                 strbuf_addch(&cmd, ' ');
 895                 sq_quote_buf(&cmd, path);
 896
 897                 /* remove repo-local variables from the environment */
 898                 conn->env = local_repo_env;
 899                 conn->use_shell = 1;
 900                 conn->in = conn->out = -1;
 901                 if (protocol == PROTO_SSH) {
 902                         const char *ssh;
 903                         int needs_batch = 0;
 904                         int port_option = 'p';
 905                         char *ssh_host = hostandport;
 906                         const char *port = NULL;
 907                         transport_check_allowed("ssh");
 908                         get_host_and_port(&ssh_host, &port);
 909
 910                         if (!port)
 911                                 port = get_port(ssh_host);
 912
 913                         if (flags & CONNECT_DIAG_URL) {
 914                                 printf("Diag: url=%s\n", url ? url : "NULL");
 915                                 printf("Diag: protocol=%s\n", prot_name(protocol));
 916                                 printf("Diag: userandhost=%s\n", ssh_host ? ssh_host : "NULL");
 917                                 printf("Diag: port=%s\n", port ? port : "NONE");
 918                                 printf("Diag: path=%s\n", path ? path : "NULL");
 919
 920                                 free(hostandport);
 921                                 free(path);
 922                                 free(conn);
 923                                 strbuf_release(&cmd);
 924                                 return NULL;
 925                         }
 926
 927                         if (looks_like_command_line_option(ssh_host))
 928                                 die("strange hostname '%s' blocked", ssh_host);
 929
 930                         ssh = get_ssh_command();
 931                         if (ssh)
 932                                 handle_ssh_variant(ssh, 1, &port_option,
 933                                                    &needs_batch);
 934                         else {
 935                                 /*
 936                                  * GIT_SSH is the no-shell version of
 937                                  * GIT_SSH_COMMAND (and must remain so for
 938                                  * historical compatibility).
 939                                  */
 940                                 conn->use_shell = 0;
 941
 942                                 ssh = getenv("GIT_SSH");
 943                                 if (!ssh)
 944                                         ssh = "ssh";
 945                                 else
 946                                         handle_ssh_variant(ssh, 0,
 947                                                            &port_option,
 948                                                            &needs_batch);
 949                         }
 950
 951                         argv_array_push(&conn->args, ssh);
 952                         if (flags & CONNECT_IPV4)
 953                                 argv_array_push(&conn->args, "-4");
 954                         else if (flags & CONNECT_IPV6)
 955                                 argv_array_push(&conn->args, "-6");
 956                         if (needs_batch)
 957                                 argv_array_push(&conn->args, "-batch");
 958                         if (port) {
 959                                 argv_array_pushf(&conn->args,
 960                                                  "-%c", port_option);
 961                                 argv_array_push(&conn->args, port);
 962                         }
 963                         argv_array_push(&conn->args, ssh_host);
 964                 } else {
 965                         transport_check_allowed("file");
 966                 }
 967                 argv_array_push(&conn->args, cmd.buf);
 968
 969                 if (start_command(conn))
 970                         die("unable to fork");
 971
 972                 fd[0] = conn->out; /* read from child's stdout */
 973                 fd[1] = conn->in;  /* write to child's stdin */
 974                 strbuf_release(&cmd);
 975         }
 976         free(hostandport);
 977         free(path);
 978         return conn;
 979 }
 980
 981 int git_connection_is_socket(struct child_process *conn)
 982 {
 983         return conn == &no_fork;
 984 }
 985
 986 int finish_connect(struct child_process *conn)
 987 {
 988         int code;
 989         if (!conn || git_connection_is_socket(conn))
 990                 return 0;
 991
 992         code = finish_command(conn);
 993         free(conn);
 994         return code;
 995 }