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