Merge branch 'rs/large-zip'
[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 unexpected)
47 {
48         if (unexpected)
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 oid_array *extra_have,
115                               struct oid_array *shallow_points)
116 {
117         struct ref **orig_list = list;
118
119         /*
120          * A hang-up after seeing some response from the other end
121          * means that it is unexpected, as we know the other end is
122          * willing to talk to us.  A hang-up before seeing any
123          * response does not necessarily mean an ACL problem, though.
124          */
125         int saw_response;
126         int got_dummy_ref_with_capabilities_declaration = 0;
127
128         *list = NULL;
129         for (saw_response = 0; ; saw_response = 1) {
130                 struct ref *ref;
131                 struct object_id old_oid;
132                 char *name;
133                 int len, name_len;
134                 char *buffer = packet_buffer;
135                 const char *arg;
136
137                 len = packet_read(in, &src_buf, &src_len,
138                                   packet_buffer, sizeof(packet_buffer),
139                                   PACKET_READ_GENTLE_ON_EOF |
140                                   PACKET_READ_CHOMP_NEWLINE);
141                 if (len < 0)
142                         die_initial_contact(saw_response);
143
144                 if (!len)
145                         break;
146
147                 if (len > 4 && skip_prefix(buffer, "ERR ", &arg))
148                         die("remote error: %s", arg);
149
150                 if (len == GIT_SHA1_HEXSZ + strlen("shallow ") &&
151                         skip_prefix(buffer, "shallow ", &arg)) {
152                         if (get_oid_hex(arg, &old_oid))
153                                 die("protocol error: expected shallow sha-1, got '%s'", arg);
154                         if (!shallow_points)
155                                 die("repository on the other end cannot be shallow");
156                         oid_array_append(shallow_points, &old_oid);
157                         continue;
158                 }
159
160                 if (len < GIT_SHA1_HEXSZ + 2 || get_oid_hex(buffer, &old_oid) ||
161                         buffer[GIT_SHA1_HEXSZ] != ' ')
162                         die("protocol error: expected sha/ref, got '%s'", buffer);
163                 name = buffer + GIT_SHA1_HEXSZ + 1;
164
165                 name_len = strlen(name);
166                 if (len != name_len + GIT_SHA1_HEXSZ + 1) {
167                         free(server_capabilities);
168                         server_capabilities = xstrdup(name + name_len + 1);
169                 }
170
171                 if (extra_have && !strcmp(name, ".have")) {
172                         oid_array_append(extra_have, &old_oid);
173                         continue;
174                 }
175
176                 if (!strcmp(name, "capabilities^{}")) {
177                         if (saw_response)
178                                 die("protocol error: unexpected capabilities^{}");
179                         if (got_dummy_ref_with_capabilities_declaration)
180                                 die("protocol error: multiple capabilities^{}");
181                         got_dummy_ref_with_capabilities_declaration = 1;
182                         continue;
183                 }
184
185                 if (!check_ref(name, flags))
186                         continue;
187
188                 if (got_dummy_ref_with_capabilities_declaration)
189                         die("protocol error: unexpected ref after capabilities^{}");
190
191                 ref = alloc_ref(buffer + GIT_SHA1_HEXSZ + 1);
192                 oidcpy(&ref->old_oid, &old_oid);
193                 *list = ref;
194                 list = &ref->next;
195         }
196
197         annotate_refs_with_symref_info(*orig_list);
198
199         return list;
200 }
201
202 static const char *parse_feature_value(const char *feature_list, const char *feature, int *lenp)
203 {
204         int len;
205
206         if (!feature_list)
207                 return NULL;
208
209         len = strlen(feature);
210         while (*feature_list) {
211                 const char *found = strstr(feature_list, feature);
212                 if (!found)
213                         return NULL;
214                 if (feature_list == found || isspace(found[-1])) {
215                         const char *value = found + len;
216                         /* feature with no value (e.g., "thin-pack") */
217                         if (!*value || isspace(*value)) {
218                                 if (lenp)
219                                         *lenp = 0;
220                                 return value;
221                         }
222                         /* feature with a value (e.g., "agent=git/1.2.3") */
223                         else if (*value == '=') {
224                                 value++;
225                                 if (lenp)
226                                         *lenp = strcspn(value, " \t\n");
227                                 return value;
228                         }
229                         /*
230                          * otherwise we matched a substring of another feature;
231                          * keep looking
232                          */
233                 }
234                 feature_list = found + 1;
235         }
236         return NULL;
237 }
238
239 int parse_feature_request(const char *feature_list, const char *feature)
240 {
241         return !!parse_feature_value(feature_list, feature, NULL);
242 }
243
244 const char *server_feature_value(const char *feature, int *len)
245 {
246         return parse_feature_value(server_capabilities, feature, len);
247 }
248
249 int server_supports(const char *feature)
250 {
251         return !!server_feature_value(feature, NULL);
252 }
253
254 enum protocol {
255         PROTO_LOCAL = 1,
256         PROTO_FILE,
257         PROTO_SSH,
258         PROTO_GIT
259 };
260
261 int url_is_local_not_ssh(const char *url)
262 {
263         const char *colon = strchr(url, ':');
264         const char *slash = strchr(url, '/');
265         return !colon || (slash && slash < colon) ||
266                 has_dos_drive_prefix(url);
267 }
268
269 static const char *prot_name(enum protocol protocol)
270 {
271         switch (protocol) {
272                 case PROTO_LOCAL:
273                 case PROTO_FILE:
274                         return "file";
275                 case PROTO_SSH:
276                         return "ssh";
277                 case PROTO_GIT:
278                         return "git";
279                 default:
280                         return "unknown protocol";
281         }
282 }
283
284 static enum protocol get_protocol(const char *name)
285 {
286         if (!strcmp(name, "ssh"))
287                 return PROTO_SSH;
288         if (!strcmp(name, "git"))
289                 return PROTO_GIT;
290         if (!strcmp(name, "git+ssh")) /* deprecated - do not use */
291                 return PROTO_SSH;
292         if (!strcmp(name, "ssh+git")) /* deprecated - do not use */
293                 return PROTO_SSH;
294         if (!strcmp(name, "file"))
295                 return PROTO_FILE;
296         die("I don't handle protocol '%s'", name);
297 }
298
299 static char *host_end(char **hoststart, int removebrackets)
300 {
301         char *host = *hoststart;
302         char *end;
303         char *start = strstr(host, "@[");
304         if (start)
305                 start++; /* Jump over '@' */
306         else
307                 start = host;
308         if (start[0] == '[') {
309                 end = strchr(start + 1, ']');
310                 if (end) {
311                         if (removebrackets) {
312                                 *end = 0;
313                                 memmove(start, start + 1, end - start);
314                                 end++;
315                         }
316                 } else
317                         end = host;
318         } else
319                 end = host;
320         return end;
321 }
322
323 #define STR_(s) # s
324 #define STR(s)  STR_(s)
325
326 static void get_host_and_port(char **host, const char **port)
327 {
328         char *colon, *end;
329         end = host_end(host, 1);
330         colon = strchr(end, ':');
331         if (colon) {
332                 long portnr = strtol(colon + 1, &end, 10);
333                 if (end != colon + 1 && *end == '\0' && 0 <= portnr && portnr < 65536) {
334                         *colon = 0;
335                         *port = colon + 1;
336                 } else if (!colon[1]) {
337                         *colon = 0;
338                 }
339         }
340 }
341
342 static void enable_keepalive(int sockfd)
343 {
344         int ka = 1;
345
346         if (setsockopt(sockfd, SOL_SOCKET, SO_KEEPALIVE, &ka, sizeof(ka)) < 0)
347                 fprintf(stderr, "unable to set SO_KEEPALIVE on socket: %s\n",
348                         strerror(errno));
349 }
350
351 #ifndef NO_IPV6
352
353 static const char *ai_name(const struct addrinfo *ai)
354 {
355         static char addr[NI_MAXHOST];
356         if (getnameinfo(ai->ai_addr, ai->ai_addrlen, addr, sizeof(addr), NULL, 0,
357                         NI_NUMERICHOST) != 0)
358                 xsnprintf(addr, sizeof(addr), "(unknown)");
359
360         return addr;
361 }
362
363 /*
364  * Returns a connected socket() fd, or else die()s.
365  */
366 static int git_tcp_connect_sock(char *host, int flags)
367 {
368         struct strbuf error_message = STRBUF_INIT;
369         int sockfd = -1;
370         const char *port = STR(DEFAULT_GIT_PORT);
371         struct addrinfo hints, *ai0, *ai;
372         int gai;
373         int cnt = 0;
374
375         get_host_and_port(&host, &port);
376         if (!*port)
377                 port = "<none>";
378
379         memset(&hints, 0, sizeof(hints));
380         if (flags & CONNECT_IPV4)
381                 hints.ai_family = AF_INET;
382         else if (flags & CONNECT_IPV6)
383                 hints.ai_family = AF_INET6;
384         hints.ai_socktype = SOCK_STREAM;
385         hints.ai_protocol = IPPROTO_TCP;
386
387         if (flags & CONNECT_VERBOSE)
388                 fprintf(stderr, "Looking up %s ... ", host);
389
390         gai = getaddrinfo(host, port, &hints, &ai);
391         if (gai)
392                 die("Unable to look up %s (port %s) (%s)", host, port, gai_strerror(gai));
393
394         if (flags & CONNECT_VERBOSE)
395                 fprintf(stderr, "done.\nConnecting to %s (port %s) ... ", host, port);
396
397         for (ai0 = ai; ai; ai = ai->ai_next, cnt++) {
398                 sockfd = socket(ai->ai_family,
399                                 ai->ai_socktype, ai->ai_protocol);
400                 if ((sockfd < 0) ||
401                     (connect(sockfd, ai->ai_addr, ai->ai_addrlen) < 0)) {
402                         strbuf_addf(&error_message, "%s[%d: %s]: errno=%s\n",
403                                     host, cnt, ai_name(ai), strerror(errno));
404                         if (0 <= sockfd)
405                                 close(sockfd);
406                         sockfd = -1;
407                         continue;
408                 }
409                 if (flags & CONNECT_VERBOSE)
410                         fprintf(stderr, "%s ", ai_name(ai));
411                 break;
412         }
413
414         freeaddrinfo(ai0);
415
416         if (sockfd < 0)
417                 die("unable to connect to %s:\n%s", host, error_message.buf);
418
419         enable_keepalive(sockfd);
420
421         if (flags & CONNECT_VERBOSE)
422                 fprintf(stderr, "done.\n");
423
424         strbuf_release(&error_message);
425
426         return sockfd;
427 }
428
429 #else /* NO_IPV6 */
430
431 /*
432  * Returns a connected socket() fd, or else die()s.
433  */
434 static int git_tcp_connect_sock(char *host, int flags)
435 {
436         struct strbuf error_message = STRBUF_INIT;
437         int sockfd = -1;
438         const char *port = STR(DEFAULT_GIT_PORT);
439         char *ep;
440         struct hostent *he;
441         struct sockaddr_in sa;
442         char **ap;
443         unsigned int nport;
444         int cnt;
445
446         get_host_and_port(&host, &port);
447
448         if (flags & CONNECT_VERBOSE)
449                 fprintf(stderr, "Looking up %s ... ", host);
450
451         he = gethostbyname(host);
452         if (!he)
453                 die("Unable to look up %s (%s)", host, hstrerror(h_errno));
454         nport = strtoul(port, &ep, 10);
455         if ( ep == port || *ep ) {
456                 /* Not numeric */
457                 struct servent *se = getservbyname(port,"tcp");
458                 if ( !se )
459                         die("Unknown port %s", port);
460                 nport = se->s_port;
461         }
462
463         if (flags & CONNECT_VERBOSE)
464                 fprintf(stderr, "done.\nConnecting to %s (port %s) ... ", host, port);
465
466         for (cnt = 0, ap = he->h_addr_list; *ap; ap++, cnt++) {
467                 memset(&sa, 0, sizeof sa);
468                 sa.sin_family = he->h_addrtype;
469                 sa.sin_port = htons(nport);
470                 memcpy(&sa.sin_addr, *ap, he->h_length);
471
472                 sockfd = socket(he->h_addrtype, SOCK_STREAM, 0);
473                 if ((sockfd < 0) ||
474                     connect(sockfd, (struct sockaddr *)&sa, sizeof sa) < 0) {
475                         strbuf_addf(&error_message, "%s[%d: %s]: errno=%s\n",
476                                 host,
477                                 cnt,
478                                 inet_ntoa(*(struct in_addr *)&sa.sin_addr),
479                                 strerror(errno));
480                         if (0 <= sockfd)
481                                 close(sockfd);
482                         sockfd = -1;
483                         continue;
484                 }
485                 if (flags & CONNECT_VERBOSE)
486                         fprintf(stderr, "%s ",
487                                 inet_ntoa(*(struct in_addr *)&sa.sin_addr));
488                 break;
489         }
490
491         if (sockfd < 0)
492                 die("unable to connect to %s:\n%s", host, error_message.buf);
493
494         enable_keepalive(sockfd);
495
496         if (flags & CONNECT_VERBOSE)
497                 fprintf(stderr, "done.\n");
498
499         return sockfd;
500 }
501
502 #endif /* NO_IPV6 */
503
504
505 static void git_tcp_connect(int fd[2], char *host, int flags)
506 {
507         int sockfd = git_tcp_connect_sock(host, flags);
508
509         fd[0] = sockfd;
510         fd[1] = dup(sockfd);
511 }
512
513
514 static char *git_proxy_command;
515
516 static int git_proxy_command_options(const char *var, const char *value,
517                 void *cb)
518 {
519         if (!strcmp(var, "core.gitproxy")) {
520                 const char *for_pos;
521                 int matchlen = -1;
522                 int hostlen;
523                 const char *rhost_name = cb;
524                 int rhost_len = strlen(rhost_name);
525
526                 if (git_proxy_command)
527                         return 0;
528                 if (!value)
529                         return config_error_nonbool(var);
530                 /* [core]
531                  * ;# matches www.kernel.org as well
532                  * gitproxy = netcatter-1 for kernel.org
533                  * gitproxy = netcatter-2 for sample.xz
534                  * gitproxy = netcatter-default
535                  */
536                 for_pos = strstr(value, " for ");
537                 if (!for_pos)
538                         /* matches everybody */
539                         matchlen = strlen(value);
540                 else {
541                         hostlen = strlen(for_pos + 5);
542                         if (rhost_len < hostlen)
543                                 matchlen = -1;
544                         else if (!strncmp(for_pos + 5,
545                                           rhost_name + rhost_len - hostlen,
546                                           hostlen) &&
547                                  ((rhost_len == hostlen) ||
548                                   rhost_name[rhost_len - hostlen -1] == '.'))
549                                 matchlen = for_pos - value;
550                         else
551                                 matchlen = -1;
552                 }
553                 if (0 <= matchlen) {
554                         /* core.gitproxy = none for kernel.org */
555                         if (matchlen == 4 &&
556                             !memcmp(value, "none", 4))
557                                 matchlen = 0;
558                         git_proxy_command = xmemdupz(value, matchlen);
559                 }
560                 return 0;
561         }
562
563         return git_default_config(var, value, cb);
564 }
565
566 static int git_use_proxy(const char *host)
567 {
568         git_proxy_command = getenv("GIT_PROXY_COMMAND");
569         git_config(git_proxy_command_options, (void*)host);
570         return (git_proxy_command && *git_proxy_command);
571 }
572
573 static struct child_process *git_proxy_connect(int fd[2], char *host)
574 {
575         const char *port = STR(DEFAULT_GIT_PORT);
576         struct child_process *proxy;
577
578         get_host_and_port(&host, &port);
579
580         proxy = xmalloc(sizeof(*proxy));
581         child_process_init(proxy);
582         argv_array_push(&proxy->args, git_proxy_command);
583         argv_array_push(&proxy->args, host);
584         argv_array_push(&proxy->args, port);
585         proxy->in = -1;
586         proxy->out = -1;
587         if (start_command(proxy))
588                 die("cannot start proxy %s", git_proxy_command);
589         fd[0] = proxy->out; /* read from proxy stdout */
590         fd[1] = proxy->in;  /* write to proxy stdin */
591         return proxy;
592 }
593
594 static char *get_port(char *host)
595 {
596         char *end;
597         char *p = strchr(host, ':');
598
599         if (p) {
600                 long port = strtol(p + 1, &end, 10);
601                 if (end != p + 1 && *end == '\0' && 0 <= port && port < 65536) {
602                         *p = '\0';
603                         return p+1;
604                 }
605         }
606
607         return NULL;
608 }
609
610 /*
611  * Extract protocol and relevant parts from the specified connection URL.
612  * The caller must free() the returned strings.
613  */
614 static enum protocol parse_connect_url(const char *url_orig, char **ret_host,
615                                        char **ret_path)
616 {
617         char *url;
618         char *host, *path;
619         char *end;
620         int separator = '/';
621         enum protocol protocol = PROTO_LOCAL;
622
623         if (is_url(url_orig))
624                 url = url_decode(url_orig);
625         else
626                 url = xstrdup(url_orig);
627
628         host = strstr(url, "://");
629         if (host) {
630                 *host = '\0';
631                 protocol = get_protocol(url);
632                 host += 3;
633         } else {
634                 host = url;
635                 if (!url_is_local_not_ssh(url)) {
636                         protocol = PROTO_SSH;
637                         separator = ':';
638                 }
639         }
640
641         /*
642          * Don't do destructive transforms as protocol code does
643          * '[]' unwrapping in get_host_and_port()
644          */
645         end = host_end(&host, 0);
646
647         if (protocol == PROTO_LOCAL)
648                 path = end;
649         else if (protocol == PROTO_FILE && has_dos_drive_prefix(end))
650                 path = end; /* "file://$(pwd)" may be "file://C:/projects/repo" */
651         else
652                 path = strchr(end, separator);
653
654         if (!path || !*path)
655                 die("No path specified. See 'man git-pull' for valid url syntax");
656
657         /*
658          * null-terminate hostname and point path to ~ for URL's like this:
659          *    ssh://host.xz/~user/repo
660          */
661
662         end = path; /* Need to \0 terminate host here */
663         if (separator == ':')
664                 path++; /* path starts after ':' */
665         if (protocol == PROTO_GIT || protocol == PROTO_SSH) {
666                 if (path[1] == '~')
667                         path++;
668         }
669
670         path = xstrdup(path);
671         *end = '\0';
672
673         *ret_host = xstrdup(host);
674         *ret_path = path;
675         free(url);
676         return protocol;
677 }
678
679 static struct child_process no_fork = CHILD_PROCESS_INIT;
680
681 static const char *get_ssh_command(void)
682 {
683         const char *ssh;
684
685         if ((ssh = getenv("GIT_SSH_COMMAND")))
686                 return ssh;
687
688         if (!git_config_get_string_const("core.sshcommand", &ssh))
689                 return ssh;
690
691         return NULL;
692 }
693
694 static int override_ssh_variant(int *port_option, int *needs_batch)
695 {
696         char *variant;
697
698         variant = xstrdup_or_null(getenv("GIT_SSH_VARIANT"));
699         if (!variant &&
700             git_config_get_string("ssh.variant", &variant))
701                 return 0;
702
703         if (!strcmp(variant, "plink") || !strcmp(variant, "putty")) {
704                 *port_option = 'P';
705                 *needs_batch = 0;
706         } else if (!strcmp(variant, "tortoiseplink")) {
707                 *port_option = 'P';
708                 *needs_batch = 1;
709         } else {
710                 *port_option = 'p';
711                 *needs_batch = 0;
712         }
713         free(variant);
714         return 1;
715 }
716
717 static void handle_ssh_variant(const char *ssh_command, int is_cmdline,
718                                int *port_option, int *needs_batch)
719 {
720         const char *variant;
721         char *p = NULL;
722
723         if (override_ssh_variant(port_option, needs_batch))
724                 return;
725
726         if (!is_cmdline) {
727                 p = xstrdup(ssh_command);
728                 variant = basename(p);
729         } else {
730                 const char **ssh_argv;
731
732                 p = xstrdup(ssh_command);
733                 if (split_cmdline(p, &ssh_argv) > 0) {
734                         variant = basename((char *)ssh_argv[0]);
735                         /*
736                          * At this point, variant points into the buffer
737                          * referenced by p, hence we do not need ssh_argv
738                          * any longer.
739                          */
740                         free(ssh_argv);
741                 } else {
742                         free(p);
743                         return;
744                 }
745         }
746
747         if (!strcasecmp(variant, "plink") ||
748             !strcasecmp(variant, "plink.exe"))
749                 *port_option = 'P';
750         else if (!strcasecmp(variant, "tortoiseplink") ||
751                  !strcasecmp(variant, "tortoiseplink.exe")) {
752                 *port_option = 'P';
753                 *needs_batch = 1;
754         }
755         free(p);
756 }
757
758 /*
759  * This returns a dummy child_process if the transport protocol does not
760  * need fork(2), or a struct child_process object if it does.  Once done,
761  * finish the connection with finish_connect() with the value returned from
762  * this function (it is safe to call finish_connect() with NULL to support
763  * the former case).
764  *
765  * If it returns, the connect is successful; it just dies on errors (this
766  * will hopefully be changed in a libification effort, to return NULL when
767  * the connection failed).
768  */
769 struct child_process *git_connect(int fd[2], const char *url,
770                                   const char *prog, int flags)
771 {
772         char *hostandport, *path;
773         struct child_process *conn = &no_fork;
774         enum protocol protocol;
775         struct strbuf cmd = STRBUF_INIT;
776
777         /* Without this we cannot rely on waitpid() to tell
778          * what happened to our children.
779          */
780         signal(SIGCHLD, SIG_DFL);
781
782         protocol = parse_connect_url(url, &hostandport, &path);
783         if ((flags & CONNECT_DIAG_URL) && (protocol != PROTO_SSH)) {
784                 printf("Diag: url=%s\n", url ? url : "NULL");
785                 printf("Diag: protocol=%s\n", prot_name(protocol));
786                 printf("Diag: hostandport=%s\n", hostandport ? hostandport : "NULL");
787                 printf("Diag: path=%s\n", path ? path : "NULL");
788                 conn = NULL;
789         } else if (protocol == PROTO_GIT) {
790                 /*
791                  * Set up virtual host information based on where we will
792                  * connect, unless the user has overridden us in
793                  * the environment.
794                  */
795                 char *target_host = getenv("GIT_OVERRIDE_VIRTUAL_HOST");
796                 if (target_host)
797                         target_host = xstrdup(target_host);
798                 else
799                         target_host = xstrdup(hostandport);
800
801                 transport_check_allowed("git");
802
803                 /* These underlying connection commands die() if they
804                  * cannot connect.
805                  */
806                 if (git_use_proxy(hostandport))
807                         conn = git_proxy_connect(fd, hostandport);
808                 else
809                         git_tcp_connect(fd, hostandport, flags);
810                 /*
811                  * Separate original protocol components prog and path
812                  * from extended host header with a NUL byte.
813                  *
814                  * Note: Do not add any other headers here!  Doing so
815                  * will cause older git-daemon servers to crash.
816                  */
817                 packet_write_fmt(fd[1],
818                              "%s %s%chost=%s%c",
819                              prog, path, 0,
820                              target_host, 0);
821                 free(target_host);
822         } else {
823                 conn = xmalloc(sizeof(*conn));
824                 child_process_init(conn);
825
826                 strbuf_addstr(&cmd, prog);
827                 strbuf_addch(&cmd, ' ');
828                 sq_quote_buf(&cmd, path);
829
830                 /* remove repo-local variables from the environment */
831                 conn->env = local_repo_env;
832                 conn->use_shell = 1;
833                 conn->in = conn->out = -1;
834                 if (protocol == PROTO_SSH) {
835                         const char *ssh;
836                         int needs_batch = 0;
837                         int port_option = 'p';
838                         char *ssh_host = hostandport;
839                         const char *port = NULL;
840                         transport_check_allowed("ssh");
841                         get_host_and_port(&ssh_host, &port);
842
843                         if (!port)
844                                 port = get_port(ssh_host);
845
846                         if (flags & CONNECT_DIAG_URL) {
847                                 printf("Diag: url=%s\n", url ? url : "NULL");
848                                 printf("Diag: protocol=%s\n", prot_name(protocol));
849                                 printf("Diag: userandhost=%s\n", ssh_host ? ssh_host : "NULL");
850                                 printf("Diag: port=%s\n", port ? port : "NONE");
851                                 printf("Diag: path=%s\n", path ? path : "NULL");
852
853                                 free(hostandport);
854                                 free(path);
855                                 free(conn);
856                                 return NULL;
857                         }
858
859                         ssh = get_ssh_command();
860                         if (ssh)
861                                 handle_ssh_variant(ssh, 1, &port_option,
862                                                    &needs_batch);
863                         else {
864                                 /*
865                                  * GIT_SSH is the no-shell version of
866                                  * GIT_SSH_COMMAND (and must remain so for
867                                  * historical compatibility).
868                                  */
869                                 conn->use_shell = 0;
870
871                                 ssh = getenv("GIT_SSH");
872                                 if (!ssh)
873                                         ssh = "ssh";
874                                 else
875                                         handle_ssh_variant(ssh, 0,
876                                                            &port_option,
877                                                            &needs_batch);
878                         }
879
880                         argv_array_push(&conn->args, ssh);
881                         if (flags & CONNECT_IPV4)
882                                 argv_array_push(&conn->args, "-4");
883                         else if (flags & CONNECT_IPV6)
884                                 argv_array_push(&conn->args, "-6");
885                         if (needs_batch)
886                                 argv_array_push(&conn->args, "-batch");
887                         if (port) {
888                                 argv_array_pushf(&conn->args,
889                                                  "-%c", port_option);
890                                 argv_array_push(&conn->args, port);
891                         }
892                         argv_array_push(&conn->args, ssh_host);
893                 } else {
894                         transport_check_allowed("file");
895                 }
896                 argv_array_push(&conn->args, cmd.buf);
897
898                 if (start_command(conn))
899                         die("unable to fork");
900
901                 fd[0] = conn->out; /* read from child's stdout */
902                 fd[1] = conn->in;  /* write to child's stdin */
903                 strbuf_release(&cmd);
904         }
905         free(hostandport);
906         free(path);
907         return conn;
908 }
909
910 int git_connection_is_socket(struct child_process *conn)
911 {
912         return conn == &no_fork;
913 }
914
915 int finish_connect(struct child_process *conn)
916 {
917         int code;
918         if (!conn || git_connection_is_socket(conn))
919                 return 0;
920
921         code = finish_command(conn);
922         free(conn);
923         return code;
924 }