merge(third_party/git): Merge squashed git subtree at v2.23.0 r/373

Merge commit '1b593e1ea4d2af0f6444d9a7788d5d99abd6fde5' as 'third_party/git'

1 files changed, 1327 insertions, 0 deletions

diff --git a/third_party/git/connect.c b/third_party/git/connect.c
new file mode 100644
index 0000000000..2778481264
--- /dev/null
+++ b/third_party/git/connect.c
@@ -0,0 +1,1327 @@
+#include "git-compat-util.h"
+#include "cache.h"
+#include "config.h"
+#include "pkt-line.h"
+#include "quote.h"
+#include "refs.h"
+#include "run-command.h"
+#include "remote.h"
+#include "connect.h"
+#include "url.h"
+#include "string-list.h"
+#include "sha1-array.h"
+#include "transport.h"
+#include "strbuf.h"
+#include "version.h"
+#include "protocol.h"
+#include "alias.h"
+
+static char *server_capabilities_v1;
+static struct argv_array server_capabilities_v2 = ARGV_ARRAY_INIT;
+static const char *parse_feature_value(const char *, const char *, int *);
+
+static int check_ref(const char *name, unsigned int flags)
+{
+	if (!flags)
+		return 1;
+
+	if (!skip_prefix(name, "refs/", &name))
+		return 0;
+
+	/* REF_NORMAL means that we don't want the magic fake tag refs */
+	if ((flags & REF_NORMAL) && check_refname_format(name, 0))
+		return 0;
+
+	/* REF_HEADS means that we want regular branch heads */
+	if ((flags & REF_HEADS) && starts_with(name, "heads/"))
+		return 1;
+
+	/* REF_TAGS means that we want tags */
+	if ((flags & REF_TAGS) && starts_with(name, "tags/"))
+		return 1;
+
+	/* All type bits clear means that we are ok with anything */
+	return !(flags & ~REF_NORMAL);
+}
+
+int check_ref_type(const struct ref *ref, int flags)
+{
+	return check_ref(ref->name, flags);
+}
+
+static NORETURN void die_initial_contact(int unexpected)
+{
+	/*
+	 * A hang-up after seeing some response from the other end
+	 * means that it is unexpected, as we know the other end is
+	 * willing to talk to us.  A hang-up before seeing any
+	 * response does not necessarily mean an ACL problem, though.
+	 */
+	if (unexpected)
+		die(_("the remote end hung up upon initial contact"));
+	else
+		die(_("Could not read from remote repository.\n\n"
+		      "Please make sure you have the correct access rights\n"
+		      "and the repository exists."));
+}
+
+/* Checks if the server supports the capability 'c' */
+int server_supports_v2(const char *c, int die_on_error)
+{
+	int i;
+
+	for (i = 0; i < server_capabilities_v2.argc; i++) {
+		const char *out;
+		if (skip_prefix(server_capabilities_v2.argv[i], c, &out) &&
+		    (!*out || *out == '='))
+			return 1;
+	}
+
+	if (die_on_error)
+		die(_("server doesn't support '%s'"), c);
+
+	return 0;
+}
+
+int server_supports_feature(const char *c, const char *feature,
+			    int die_on_error)
+{
+	int i;
+
+	for (i = 0; i < server_capabilities_v2.argc; i++) {
+		const char *out;
+		if (skip_prefix(server_capabilities_v2.argv[i], c, &out) &&
+		    (!*out || *(out++) == '=')) {
+			if (parse_feature_request(out, feature))
+				return 1;
+			else
+				break;
+		}
+	}
+
+	if (die_on_error)
+		die(_("server doesn't support feature '%s'"), feature);
+
+	return 0;
+}
+
+static void process_capabilities_v2(struct packet_reader *reader)
+{
+	while (packet_reader_read(reader) == PACKET_READ_NORMAL)
+		argv_array_push(&server_capabilities_v2, reader->line);
+
+	if (reader->status != PACKET_READ_FLUSH)
+		die(_("expected flush after capabilities"));
+}
+
+enum protocol_version discover_version(struct packet_reader *reader)
+{
+	enum protocol_version version = protocol_unknown_version;
+
+	/*
+	 * Peek the first line of the server's response to
+	 * determine the protocol version the server is speaking.
+	 */
+	switch (packet_reader_peek(reader)) {
+	case PACKET_READ_EOF:
+		die_initial_contact(0);
+	case PACKET_READ_FLUSH:
+	case PACKET_READ_DELIM:
+		version = protocol_v0;
+		break;
+	case PACKET_READ_NORMAL:
+		version = determine_protocol_version_client(reader->line);
+		break;
+	}
+
+	switch (version) {
+	case protocol_v2:
+		process_capabilities_v2(reader);
+		break;
+	case protocol_v1:
+		/* Read the peeked version line */
+		packet_reader_read(reader);
+		break;
+	case protocol_v0:
+		break;
+	case protocol_unknown_version:
+		BUG("unknown protocol version");
+	}
+
+	return version;
+}
+
+static void parse_one_symref_info(struct string_list *symref, const char *val, int len)
+{
+	char *sym, *target;
+	struct string_list_item *item;
+
+	if (!len)
+		return; /* just "symref" */
+	/* e.g. "symref=HEAD:refs/heads/master" */
+	sym = xmemdupz(val, len);
+	target = strchr(sym, ':');
+	if (!target)
+		/* just "symref=something" */
+		goto reject;
+	*(target++) = '\0';
+	if (check_refname_format(sym, REFNAME_ALLOW_ONELEVEL) ||
+	    check_refname_format(target, REFNAME_ALLOW_ONELEVEL))
+		/* "symref=bogus:pair */
+		goto reject;
+	item = string_list_append_nodup(symref, sym);
+	item->util = target;
+	return;
+reject:
+	free(sym);
+	return;
+}
+
+static void annotate_refs_with_symref_info(struct ref *ref)
+{
+	struct string_list symref = STRING_LIST_INIT_DUP;
+	const char *feature_list = server_capabilities_v1;
+
+	while (feature_list) {
+		int len;
+		const char *val;
+
+		val = parse_feature_value(feature_list, "symref", &len);
+		if (!val)
+			break;
+		parse_one_symref_info(&symref, val, len);
+		feature_list = val + 1;
+	}
+	string_list_sort(&symref);
+
+	for (; ref; ref = ref->next) {
+		struct string_list_item *item;
+		item = string_list_lookup(&symref, ref->name);
+		if (!item)
+			continue;
+		ref->symref = xstrdup((char *)item->util);
+	}
+	string_list_clear(&symref, 0);
+}
+
+static void process_capabilities(const char *line, int *len)
+{
+	int nul_location = strlen(line);
+	if (nul_location == *len)
+		return;
+	server_capabilities_v1 = xstrdup(line + nul_location + 1);
+	*len = nul_location;
+}
+
+static int process_dummy_ref(const char *line)
+{
+	struct object_id oid;
+	const char *name;
+
+	if (parse_oid_hex(line, &oid, &name))
+		return 0;
+	if (*name != ' ')
+		return 0;
+	name++;
+
+	return oideq(&null_oid, &oid) && !strcmp(name, "capabilities^{}");
+}
+
+static void check_no_capabilities(const char *line, int len)
+{
+	if (strlen(line) != len)
+		warning(_("ignoring capabilities after first line '%s'"),
+			line + strlen(line));
+}
+
+static int process_ref(const char *line, int len, struct ref ***list,
+		       unsigned int flags, struct oid_array *extra_have)
+{
+	struct object_id old_oid;
+	const char *name;
+
+	if (parse_oid_hex(line, &old_oid, &name))
+		return 0;
+	if (*name != ' ')
+		return 0;
+	name++;
+
+	if (extra_have && !strcmp(name, ".have")) {
+		oid_array_append(extra_have, &old_oid);
+	} else if (!strcmp(name, "capabilities^{}")) {
+		die(_("protocol error: unexpected capabilities^{}"));
+	} else if (check_ref(name, flags)) {
+		struct ref *ref = alloc_ref(name);
+		oidcpy(&ref->old_oid, &old_oid);
+		**list = ref;
+		*list = &ref->next;
+	}
+	check_no_capabilities(line, len);
+	return 1;
+}
+
+static int process_shallow(const char *line, int len,
+			   struct oid_array *shallow_points)
+{
+	const char *arg;
+	struct object_id old_oid;
+
+	if (!skip_prefix(line, "shallow ", &arg))
+		return 0;
+
+	if (get_oid_hex(arg, &old_oid))
+		die(_("protocol error: expected shallow sha-1, got '%s'"), arg);
+	if (!shallow_points)
+		die(_("repository on the other end cannot be shallow"));
+	oid_array_append(shallow_points, &old_oid);
+	check_no_capabilities(line, len);
+	return 1;
+}
+
+enum get_remote_heads_state {
+	EXPECTING_FIRST_REF = 0,
+	EXPECTING_REF,
+	EXPECTING_SHALLOW,
+	EXPECTING_DONE,
+};
+
+/*
+ * Read all the refs from the other end
+ */
+struct ref **get_remote_heads(struct packet_reader *reader,
+			      struct ref **list, unsigned int flags,
+			      struct oid_array *extra_have,
+			      struct oid_array *shallow_points)
+{
+	struct ref **orig_list = list;
+	int len = 0;
+	enum get_remote_heads_state state = EXPECTING_FIRST_REF;
+
+	*list = NULL;
+
+	while (state != EXPECTING_DONE) {
+		switch (packet_reader_read(reader)) {
+		case PACKET_READ_EOF:
+			die_initial_contact(1);
+		case PACKET_READ_NORMAL:
+			len = reader->pktlen;
+			break;
+		case PACKET_READ_FLUSH:
+			state = EXPECTING_DONE;
+			break;
+		case PACKET_READ_DELIM:
+			die(_("invalid packet"));
+		}
+
+		switch (state) {
+		case EXPECTING_FIRST_REF:
+			process_capabilities(reader->line, &len);
+			if (process_dummy_ref(reader->line)) {
+				state = EXPECTING_SHALLOW;
+				break;
+			}
+			state = EXPECTING_REF;
+			/* fallthrough */
+		case EXPECTING_REF:
+			if (process_ref(reader->line, len, &list, flags, extra_have))
+				break;
+			state = EXPECTING_SHALLOW;
+			/* fallthrough */
+		case EXPECTING_SHALLOW:
+			if (process_shallow(reader->line, len, shallow_points))
+				break;
+			die(_("protocol error: unexpected '%s'"), reader->line);
+		case EXPECTING_DONE:
+			break;
+		}
+	}
+
+	annotate_refs_with_symref_info(*orig_list);
+
+	return list;
+}
+
+/* Returns 1 when a valid ref has been added to `list`, 0 otherwise */
+static int process_ref_v2(const char *line, struct ref ***list)
+{
+	int ret = 1;
+	int i = 0;
+	struct object_id old_oid;
+	struct ref *ref;
+	struct string_list line_sections = STRING_LIST_INIT_DUP;
+	const char *end;
+
+	/*
+	 * Ref lines have a number of fields which are space deliminated.  The
+	 * first field is the OID of the ref.  The second field is the ref
+	 * name.  Subsequent fields (symref-target and peeled) are optional and
+	 * don't have a particular order.
+	 */
+	if (string_list_split(&line_sections, line, ' ', -1) < 2) {
+		ret = 0;
+		goto out;
+	}
+
+	if (parse_oid_hex(line_sections.items[i++].string, &old_oid, &end) ||
+	    *end) {
+		ret = 0;
+		goto out;
+	}
+
+	ref = alloc_ref(line_sections.items[i++].string);
+
+	oidcpy(&ref->old_oid, &old_oid);
+	**list = ref;
+	*list = &ref->next;
+
+	for (; i < line_sections.nr; i++) {
+		const char *arg = line_sections.items[i].string;
+		if (skip_prefix(arg, "symref-target:", &arg))
+			ref->symref = xstrdup(arg);
+
+		if (skip_prefix(arg, "peeled:", &arg)) {
+			struct object_id peeled_oid;
+			char *peeled_name;
+			struct ref *peeled;
+			if (parse_oid_hex(arg, &peeled_oid, &end) || *end) {
+				ret = 0;
+				goto out;
+			}
+
+			peeled_name = xstrfmt("%s^{}", ref->name);
+			peeled = alloc_ref(peeled_name);
+
+			oidcpy(&peeled->old_oid, &peeled_oid);
+			**list = peeled;
+			*list = &peeled->next;
+
+			free(peeled_name);
+		}
+	}
+
+out:
+	string_list_clear(&line_sections, 0);
+	return ret;
+}
+
+struct ref **get_remote_refs(int fd_out, struct packet_reader *reader,
+			     struct ref **list, int for_push,
+			     const struct argv_array *ref_prefixes,
+			     const struct string_list *server_options)
+{
+	int i;
+	*list = NULL;
+
+	if (server_supports_v2("ls-refs", 1))
+		packet_write_fmt(fd_out, "command=ls-refs\n");
+
+	if (server_supports_v2("agent", 0))
+		packet_write_fmt(fd_out, "agent=%s", git_user_agent_sanitized());
+
+	if (server_options && server_options->nr &&
+	    server_supports_v2("server-option", 1))
+		for (i = 0; i < server_options->nr; i++)
+			packet_write_fmt(fd_out, "server-option=%s",
+					 server_options->items[i].string);
+
+	packet_delim(fd_out);
+	/* When pushing we don't want to request the peeled tags */
+	if (!for_push)
+		packet_write_fmt(fd_out, "peel\n");
+	packet_write_fmt(fd_out, "symrefs\n");
+	for (i = 0; ref_prefixes && i < ref_prefixes->argc; i++) {
+		packet_write_fmt(fd_out, "ref-prefix %s\n",
+				 ref_prefixes->argv[i]);
+	}
+	packet_flush(fd_out);
+
+	/* Process response from server */
+	while (packet_reader_read(reader) == PACKET_READ_NORMAL) {
+		if (!process_ref_v2(reader->line, &list))
+			die(_("invalid ls-refs response: %s"), reader->line);
+	}
+
+	if (reader->status != PACKET_READ_FLUSH)
+		die(_("expected flush after ref listing"));
+
+	return list;
+}
+
+static const char *parse_feature_value(const char *feature_list, const char *feature, int *lenp)
+{
+	int len;
+
+	if (!feature_list)
+		return NULL;
+
+	len = strlen(feature);
+	while (*feature_list) {
+		const char *found = strstr(feature_list, feature);
+		if (!found)
+			return NULL;
+		if (feature_list == found || isspace(found[-1])) {
+			const char *value = found + len;
+			/* feature with no value (e.g., "thin-pack") */
+			if (!*value || isspace(*value)) {
+				if (lenp)
+					*lenp = 0;
+				return value;
+			}
+			/* feature with a value (e.g., "agent=git/1.2.3") */
+			else if (*value == '=') {
+				value++;
+				if (lenp)
+					*lenp = strcspn(value, " \t\n");
+				return value;
+			}
+			/*
+			 * otherwise we matched a substring of another feature;
+			 * keep looking
+			 */
+		}
+		feature_list = found + 1;
+	}
+	return NULL;
+}
+
+int parse_feature_request(const char *feature_list, const char *feature)
+{
+	return !!parse_feature_value(feature_list, feature, NULL);
+}
+
+const char *server_feature_value(const char *feature, int *len)
+{
+	return parse_feature_value(server_capabilities_v1, feature, len);
+}
+
+int server_supports(const char *feature)
+{
+	return !!server_feature_value(feature, NULL);
+}
+
+enum protocol {
+	PROTO_LOCAL = 1,
+	PROTO_FILE,
+	PROTO_SSH,
+	PROTO_GIT
+};
+
+int url_is_local_not_ssh(const char *url)
+{
+	const char *colon = strchr(url, ':');
+	const char *slash = strchr(url, '/');
+	return !colon || (slash && slash < colon) ||
+		has_dos_drive_prefix(url);
+}
+
+static const char *prot_name(enum protocol protocol)
+{
+	switch (protocol) {
+		case PROTO_LOCAL:
+		case PROTO_FILE:
+			return "file";
+		case PROTO_SSH:
+			return "ssh";
+		case PROTO_GIT:
+			return "git";
+		default:
+			return "unknown protocol";
+	}
+}
+
+static enum protocol get_protocol(const char *name)
+{
+	if (!strcmp(name, "ssh"))
+		return PROTO_SSH;
+	if (!strcmp(name, "git"))
+		return PROTO_GIT;
+	if (!strcmp(name, "git+ssh")) /* deprecated - do not use */
+		return PROTO_SSH;
+	if (!strcmp(name, "ssh+git")) /* deprecated - do not use */
+		return PROTO_SSH;
+	if (!strcmp(name, "file"))
+		return PROTO_FILE;
+	die(_("protocol '%s' is not supported"), name);
+}
+
+static char *host_end(char **hoststart, int removebrackets)
+{
+	char *host = *hoststart;
+	char *end;
+	char *start = strstr(host, "@[");
+	if (start)
+		start++; /* Jump over '@' */
+	else
+		start = host;
+	if (start[0] == '[') {
+		end = strchr(start + 1, ']');
+		if (end) {
+			if (removebrackets) {
+				*end = 0;
+				memmove(start, start + 1, end - start);
+				end++;
+			}
+		} else
+			end = host;
+	} else
+		end = host;
+	return end;
+}
+
+#define STR_(s)	# s
+#define STR(s)	STR_(s)
+
+static void get_host_and_port(char **host, const char **port)
+{
+	char *colon, *end;
+	end = host_end(host, 1);
+	colon = strchr(end, ':');
+	if (colon) {
+		long portnr = strtol(colon + 1, &end, 10);
+		if (end != colon + 1 && *end == '\0' && 0 <= portnr && portnr < 65536) {
+			*colon = 0;
+			*port = colon + 1;
+		} else if (!colon[1]) {
+			*colon = 0;
+		}
+	}
+}
+
+static void enable_keepalive(int sockfd)
+{
+	int ka = 1;
+
+	if (setsockopt(sockfd, SOL_SOCKET, SO_KEEPALIVE, &ka, sizeof(ka)) < 0)
+		error_errno(_("unable to set SO_KEEPALIVE on socket"));
+}
+
+#ifndef NO_IPV6
+
+static const char *ai_name(const struct addrinfo *ai)
+{
+	static char addr[NI_MAXHOST];
+	if (getnameinfo(ai->ai_addr, ai->ai_addrlen, addr, sizeof(addr), NULL, 0,
+			NI_NUMERICHOST) != 0)
+		xsnprintf(addr, sizeof(addr), "(unknown)");
+
+	return addr;
+}
+
+/*
+ * Returns a connected socket() fd, or else die()s.
+ */
+static int git_tcp_connect_sock(char *host, int flags)
+{
+	struct strbuf error_message = STRBUF_INIT;
+	int sockfd = -1;
+	const char *port = STR(DEFAULT_GIT_PORT);
+	struct addrinfo hints, *ai0, *ai;
+	int gai;
+	int cnt = 0;
+
+	get_host_and_port(&host, &port);
+	if (!*port)
+		port = "<none>";
+
+	memset(&hints, 0, sizeof(hints));
+	if (flags & CONNECT_IPV4)
+		hints.ai_family = AF_INET;
+	else if (flags & CONNECT_IPV6)
+		hints.ai_family = AF_INET6;
+	hints.ai_socktype = SOCK_STREAM;
+	hints.ai_protocol = IPPROTO_TCP;
+
+	if (flags & CONNECT_VERBOSE)
+		fprintf(stderr, _("Looking up %s ... "), host);
+
+	gai = getaddrinfo(host, port, &hints, &ai);
+	if (gai)
+		die(_("unable to look up %s (port %s) (%s)"), host, port, gai_strerror(gai));
+
+	if (flags & CONNECT_VERBOSE)
+		/* TRANSLATORS: this is the end of "Looking up %s ... " */
+		fprintf(stderr, _("done.\nConnecting to %s (port %s) ... "), host, port);
+
+	for (ai0 = ai; ai; ai = ai->ai_next, cnt++) {
+		sockfd = socket(ai->ai_family,
+				ai->ai_socktype, ai->ai_protocol);
+		if ((sockfd < 0) ||
+		    (connect(sockfd, ai->ai_addr, ai->ai_addrlen) < 0)) {
+			strbuf_addf(&error_message, "%s[%d: %s]: errno=%s\n",
+				    host, cnt, ai_name(ai), strerror(errno));
+			if (0 <= sockfd)
+				close(sockfd);
+			sockfd = -1;
+			continue;
+		}
+		if (flags & CONNECT_VERBOSE)
+			fprintf(stderr, "%s ", ai_name(ai));
+		break;
+	}
+
+	freeaddrinfo(ai0);
+
+	if (sockfd < 0)
+		die(_("unable to connect to %s:\n%s"), host, error_message.buf);
+
+	enable_keepalive(sockfd);
+
+	if (flags & CONNECT_VERBOSE)
+		/* TRANSLATORS: this is the end of "Connecting to %s (port %s) ... " */
+		fprintf_ln(stderr, _("done."));
+
+	strbuf_release(&error_message);
+
+	return sockfd;
+}
+
+#else /* NO_IPV6 */
+
+/*
+ * Returns a connected socket() fd, or else die()s.
+ */
+static int git_tcp_connect_sock(char *host, int flags)
+{
+	struct strbuf error_message = STRBUF_INIT;
+	int sockfd = -1;
+	const char *port = STR(DEFAULT_GIT_PORT);
+	char *ep;
+	struct hostent *he;
+	struct sockaddr_in sa;
+	char **ap;
+	unsigned int nport;
+	int cnt;
+
+	get_host_and_port(&host, &port);
+
+	if (flags & CONNECT_VERBOSE)
+		fprintf(stderr, _("Looking up %s ... "), host);
+
+	he = gethostbyname(host);
+	if (!he)
+		die(_("unable to look up %s (%s)"), host, hstrerror(h_errno));
+	nport = strtoul(port, &ep, 10);
+	if ( ep == port || *ep ) {
+		/* Not numeric */
+		struct servent *se = getservbyname(port,"tcp");
+		if ( !se )
+			die(_("unknown port %s"), port);
+		nport = se->s_port;
+	}
+
+	if (flags & CONNECT_VERBOSE)
+		/* TRANSLATORS: this is the end of "Looking up %s ... " */
+		fprintf(stderr, _("done.\nConnecting to %s (port %s) ... "), host, port);
+
+	for (cnt = 0, ap = he->h_addr_list; *ap; ap++, cnt++) {
+		memset(&sa, 0, sizeof sa);
+		sa.sin_family = he->h_addrtype;
+		sa.sin_port = htons(nport);
+		memcpy(&sa.sin_addr, *ap, he->h_length);
+
+		sockfd = socket(he->h_addrtype, SOCK_STREAM, 0);
+		if ((sockfd < 0) ||
+		    connect(sockfd, (struct sockaddr *)&sa, sizeof sa) < 0) {
+			strbuf_addf(&error_message, "%s[%d: %s]: errno=%s\n",
+				host,
+				cnt,
+				inet_ntoa(*(struct in_addr *)&sa.sin_addr),
+				strerror(errno));
+			if (0 <= sockfd)
+				close(sockfd);
+			sockfd = -1;
+			continue;
+		}
+		if (flags & CONNECT_VERBOSE)
+			fprintf(stderr, "%s ",
+				inet_ntoa(*(struct in_addr *)&sa.sin_addr));
+		break;
+	}
+
+	if (sockfd < 0)
+		die(_("unable to connect to %s:\n%s"), host, error_message.buf);
+
+	enable_keepalive(sockfd);
+
+	if (flags & CONNECT_VERBOSE)
+		/* TRANSLATORS: this is the end of "Connecting to %s (port %s) ... " */
+		fprintf_ln(stderr, _("done."));
+
+	return sockfd;
+}
+
+#endif /* NO_IPV6 */
+
+
+/*
+ * Dummy child_process returned by git_connect() if the transport protocol
+ * does not need fork(2).
+ */
+static struct child_process no_fork = CHILD_PROCESS_INIT;
+
+int git_connection_is_socket(struct child_process *conn)
+{
+	return conn == &no_fork;
+}
+
+static struct child_process *git_tcp_connect(int fd[2], char *host, int flags)
+{
+	int sockfd = git_tcp_connect_sock(host, flags);
+
+	fd[0] = sockfd;
+	fd[1] = dup(sockfd);
+
+	return &no_fork;
+}
+
+
+static char *git_proxy_command;
+
+static int git_proxy_command_options(const char *var, const char *value,
+		void *cb)
+{
+	if (!strcmp(var, "core.gitproxy")) {
+		const char *for_pos;
+		int matchlen = -1;
+		int hostlen;
+		const char *rhost_name = cb;
+		int rhost_len = strlen(rhost_name);
+
+		if (git_proxy_command)
+			return 0;
+		if (!value)
+			return config_error_nonbool(var);
+		/* [core]
+		 * ;# matches www.kernel.org as well
+		 * gitproxy = netcatter-1 for kernel.org
+		 * gitproxy = netcatter-2 for sample.xz
+		 * gitproxy = netcatter-default
+		 */
+		for_pos = strstr(value, " for ");
+		if (!for_pos)
+			/* matches everybody */
+			matchlen = strlen(value);
+		else {
+			hostlen = strlen(for_pos + 5);
+			if (rhost_len < hostlen)
+				matchlen = -1;
+			else if (!strncmp(for_pos + 5,
+					  rhost_name + rhost_len - hostlen,
+					  hostlen) &&
+				 ((rhost_len == hostlen) ||
+				  rhost_name[rhost_len - hostlen -1] == '.'))
+				matchlen = for_pos - value;
+			else
+				matchlen = -1;
+		}
+		if (0 <= matchlen) {
+			/* core.gitproxy = none for kernel.org */
+			if (matchlen == 4 &&
+			    !memcmp(value, "none", 4))
+				matchlen = 0;
+			git_proxy_command = xmemdupz(value, matchlen);
+		}
+		return 0;
+	}
+
+	return git_default_config(var, value, cb);
+}
+
+static int git_use_proxy(const char *host)
+{
+	git_proxy_command = getenv("GIT_PROXY_COMMAND");
+	git_config(git_proxy_command_options, (void*)host);
+	return (git_proxy_command && *git_proxy_command);
+}
+
+static struct child_process *git_proxy_connect(int fd[2], char *host)
+{
+	const char *port = STR(DEFAULT_GIT_PORT);
+	struct child_process *proxy;
+
+	get_host_and_port(&host, &port);
+
+	if (looks_like_command_line_option(host))
+		die(_("strange hostname '%s' blocked"), host);
+	if (looks_like_command_line_option(port))
+		die(_("strange port '%s' blocked"), port);
+
+	proxy = xmalloc(sizeof(*proxy));
+	child_process_init(proxy);
+	argv_array_push(&proxy->args, git_proxy_command);
+	argv_array_push(&proxy->args, host);
+	argv_array_push(&proxy->args, port);
+	proxy->in = -1;
+	proxy->out = -1;
+	if (start_command(proxy))
+		die(_("cannot start proxy %s"), git_proxy_command);
+	fd[0] = proxy->out; /* read from proxy stdout */
+	fd[1] = proxy->in;  /* write to proxy stdin */
+	return proxy;
+}
+
+static char *get_port(char *host)
+{
+	char *end;
+	char *p = strchr(host, ':');
+
+	if (p) {
+		long port = strtol(p + 1, &end, 10);
+		if (end != p + 1 && *end == '\0' && 0 <= port && port < 65536) {
+			*p = '\0';
+			return p+1;
+		}
+	}
+
+	return NULL;
+}
+
+/*
+ * Extract protocol and relevant parts from the specified connection URL.
+ * The caller must free() the returned strings.
+ */
+static enum protocol parse_connect_url(const char *url_orig, char **ret_host,
+				       char **ret_path)
+{
+	char *url;
+	char *host, *path;
+	char *end;
+	int separator = '/';
+	enum protocol protocol = PROTO_LOCAL;
+
+	if (is_url(url_orig))
+		url = url_decode(url_orig);
+	else
+		url = xstrdup(url_orig);
+
+	host = strstr(url, "://");
+	if (host) {
+		*host = '\0';
+		protocol = get_protocol(url);
+		host += 3;
+	} else {
+		host = url;
+		if (!url_is_local_not_ssh(url)) {
+			protocol = PROTO_SSH;
+			separator = ':';
+		}
+	}
+
+	/*
+	 * Don't do destructive transforms as protocol code does
+	 * '[]' unwrapping in get_host_and_port()
+	 */
+	end = host_end(&host, 0);
+
+	if (protocol == PROTO_LOCAL)
+		path = end;
+	else if (protocol == PROTO_FILE && has_dos_drive_prefix(end))
+		path = end; /* "file://$(pwd)" may be "file://C:/projects/repo" */
+	else
+		path = strchr(end, separator);
+
+	if (!path || !*path)
+		die(_("no path specified; see 'git help pull' for valid url syntax"));
+
+	/*
+	 * null-terminate hostname and point path to ~ for URL's like this:
+	 *    ssh://host.xz/~user/repo
+	 */
+
+	end = path; /* Need to \0 terminate host here */
+	if (separator == ':')
+		path++; /* path starts after ':' */
+	if (protocol == PROTO_GIT || protocol == PROTO_SSH) {
+		if (path[1] == '~')
+			path++;
+	}
+
+	path = xstrdup(path);
+	*end = '\0';
+
+	*ret_host = xstrdup(host);
+	*ret_path = path;
+	free(url);
+	return protocol;
+}
+
+static const char *get_ssh_command(void)
+{
+	const char *ssh;
+
+	if ((ssh = getenv("GIT_SSH_COMMAND")))
+		return ssh;
+
+	if (!git_config_get_string_const("core.sshcommand", &ssh))
+		return ssh;
+
+	return NULL;
+}
+
+enum ssh_variant {
+	VARIANT_AUTO,
+	VARIANT_SIMPLE,
+	VARIANT_SSH,
+	VARIANT_PLINK,
+	VARIANT_PUTTY,
+	VARIANT_TORTOISEPLINK,
+};
+
+static void override_ssh_variant(enum ssh_variant *ssh_variant)
+{
+	const char *variant = getenv("GIT_SSH_VARIANT");
+
+	if (!variant && git_config_get_string_const("ssh.variant", &variant))
+		return;
+
+	if (!strcmp(variant, "auto"))
+		*ssh_variant = VARIANT_AUTO;
+	else if (!strcmp(variant, "plink"))
+		*ssh_variant = VARIANT_PLINK;
+	else if (!strcmp(variant, "putty"))
+		*ssh_variant = VARIANT_PUTTY;
+	else if (!strcmp(variant, "tortoiseplink"))
+		*ssh_variant = VARIANT_TORTOISEPLINK;
+	else if (!strcmp(variant, "simple"))
+		*ssh_variant = VARIANT_SIMPLE;
+	else
+		*ssh_variant = VARIANT_SSH;
+}
+
+static enum ssh_variant determine_ssh_variant(const char *ssh_command,
+					      int is_cmdline)
+{
+	enum ssh_variant ssh_variant = VARIANT_AUTO;
+	const char *variant;
+	char *p = NULL;
+
+	override_ssh_variant(&ssh_variant);
+
+	if (ssh_variant != VARIANT_AUTO)
+		return ssh_variant;
+
+	if (!is_cmdline) {
+		p = xstrdup(ssh_command);
+		variant = basename(p);
+	} else {
+		const char **ssh_argv;
+
+		p = xstrdup(ssh_command);
+		if (split_cmdline(p, &ssh_argv) > 0) {
+			variant = basename((char *)ssh_argv[0]);
+			/*
+			 * At this point, variant points into the buffer
+			 * referenced by p, hence we do not need ssh_argv
+			 * any longer.
+			 */
+			free(ssh_argv);
+		} else {
+			free(p);
+			return ssh_variant;
+		}
+	}
+
+	if (!strcasecmp(variant, "ssh") ||
+	    !strcasecmp(variant, "ssh.exe"))
+		ssh_variant = VARIANT_SSH;
+	else if (!strcasecmp(variant, "plink") ||
+		 !strcasecmp(variant, "plink.exe"))
+		ssh_variant = VARIANT_PLINK;
+	else if (!strcasecmp(variant, "tortoiseplink") ||
+		 !strcasecmp(variant, "tortoiseplink.exe"))
+		ssh_variant = VARIANT_TORTOISEPLINK;
+
+	free(p);
+	return ssh_variant;
+}
+
+/*
+ * Open a connection using Git's native protocol.
+ *
+ * The caller is responsible for freeing hostandport, but this function may
+ * modify it (for example, to truncate it to remove the port part).
+ */
+static struct child_process *git_connect_git(int fd[2], char *hostandport,
+					     const char *path, const char *prog,
+					     enum protocol_version version,
+					     int flags)
+{
+	struct child_process *conn;
+	struct strbuf request = STRBUF_INIT;
+	/*
+	 * Set up virtual host information based on where we will
+	 * connect, unless the user has overridden us in
+	 * the environment.
+	 */
+	char *target_host = getenv("GIT_OVERRIDE_VIRTUAL_HOST");
+	if (target_host)
+		target_host = xstrdup(target_host);
+	else
+		target_host = xstrdup(hostandport);
+
+	transport_check_allowed("git");
+
+	/*
+	 * These underlying connection commands die() if they
+	 * cannot connect.
+	 */
+	if (git_use_proxy(hostandport))
+		conn = git_proxy_connect(fd, hostandport);
+	else
+		conn = git_tcp_connect(fd, hostandport, flags);
+	/*
+	 * Separate original protocol components prog and path
+	 * from extended host header with a NUL byte.
+	 *
+	 * Note: Do not add any other headers here!  Doing so
+	 * will cause older git-daemon servers to crash.
+	 */
+	strbuf_addf(&request,
+		    "%s %s%chost=%s%c",
+		    prog, path, 0,
+		    target_host, 0);
+
+	/* If using a new version put that stuff here after a second null byte */
+	if (version > 0) {
+		strbuf_addch(&request, '\0');
+		strbuf_addf(&request, "version=%d%c",
+			    version, '\0');
+	}
+
+	packet_write(fd[1], request.buf, request.len);
+
+	free(target_host);
+	strbuf_release(&request);
+	return conn;
+}
+
+/*
+ * Append the appropriate environment variables to `env` and options to
+ * `args` for running ssh in Git's SSH-tunneled transport.
+ */
+static void push_ssh_options(struct argv_array *args, struct argv_array *env,
+			     enum ssh_variant variant, const char *port,
+			     enum protocol_version version, int flags)
+{
+	if (variant == VARIANT_SSH &&
+	    version > 0) {
+		argv_array_push(args, "-o");
+		argv_array_push(args, "SendEnv=" GIT_PROTOCOL_ENVIRONMENT);
+		argv_array_pushf(env, GIT_PROTOCOL_ENVIRONMENT "=version=%d",
+				 version);
+	}
+
+	if (flags & CONNECT_IPV4) {
+		switch (variant) {
+		case VARIANT_AUTO:
+			BUG("VARIANT_AUTO passed to push_ssh_options");
+		case VARIANT_SIMPLE:
+			die(_("ssh variant 'simple' does not support -4"));
+		case VARIANT_SSH:
+		case VARIANT_PLINK:
+		case VARIANT_PUTTY:
+		case VARIANT_TORTOISEPLINK:
+			argv_array_push(args, "-4");
+		}
+	} else if (flags & CONNECT_IPV6) {
+		switch (variant) {
+		case VARIANT_AUTO:
+			BUG("VARIANT_AUTO passed to push_ssh_options");
+		case VARIANT_SIMPLE:
+			die(_("ssh variant 'simple' does not support -6"));
+		case VARIANT_SSH:
+		case VARIANT_PLINK:
+		case VARIANT_PUTTY:
+		case VARIANT_TORTOISEPLINK:
+			argv_array_push(args, "-6");
+		}
+	}
+
+	if (variant == VARIANT_TORTOISEPLINK)
+		argv_array_push(args, "-batch");
+
+	if (port) {
+		switch (variant) {
+		case VARIANT_AUTO:
+			BUG("VARIANT_AUTO passed to push_ssh_options");
+		case VARIANT_SIMPLE:
+			die(_("ssh variant 'simple' does not support setting port"));
+		case VARIANT_SSH:
+			argv_array_push(args, "-p");
+			break;
+		case VARIANT_PLINK:
+		case VARIANT_PUTTY:
+		case VARIANT_TORTOISEPLINK:
+			argv_array_push(args, "-P");
+		}
+
+		argv_array_push(args, port);
+	}
+}
+
+/* Prepare a child_process for use by Git's SSH-tunneled transport. */
+static void fill_ssh_args(struct child_process *conn, const char *ssh_host,
+			  const char *port, enum protocol_version version,
+			  int flags)
+{
+	const char *ssh;
+	enum ssh_variant variant;
+
+	if (looks_like_command_line_option(ssh_host))
+		die(_("strange hostname '%s' blocked"), ssh_host);
+
+	ssh = get_ssh_command();
+	if (ssh) {
+		variant = determine_ssh_variant(ssh, 1);
+	} else {
+		/*
+		 * GIT_SSH is the no-shell version of
+		 * GIT_SSH_COMMAND (and must remain so for
+		 * historical compatibility).
+		 */
+		conn->use_shell = 0;
+
+		ssh = getenv("GIT_SSH");
+		if (!ssh)
+			ssh = "ssh";
+		variant = determine_ssh_variant(ssh, 0);
+	}
+
+	if (variant == VARIANT_AUTO) {
+		struct child_process detect = CHILD_PROCESS_INIT;
+
+		detect.use_shell = conn->use_shell;
+		detect.no_stdin = detect.no_stdout = detect.no_stderr = 1;
+
+		argv_array_push(&detect.args, ssh);
+		argv_array_push(&detect.args, "-G");
+		push_ssh_options(&detect.args, &detect.env_array,
+				 VARIANT_SSH, port, version, flags);
+		argv_array_push(&detect.args, ssh_host);
+
+		variant = run_command(&detect) ? VARIANT_SIMPLE : VARIANT_SSH;
+	}
+
+	argv_array_push(&conn->args, ssh);
+	push_ssh_options(&conn->args, &conn->env_array, variant, port, version, flags);
+	argv_array_push(&conn->args, ssh_host);
+}
+
+/*
+ * This returns the dummy child_process `no_fork` if the transport protocol
+ * does not need fork(2), or a struct child_process object if it does.  Once
+ * done, finish the connection with finish_connect() with the value returned
+ * from this function (it is safe to call finish_connect() with NULL to
+ * support the former case).
+ *
+ * If it returns, the connect is successful; it just dies on errors (this
+ * will hopefully be changed in a libification effort, to return NULL when
+ * the connection failed).
+ */
+struct child_process *git_connect(int fd[2], const char *url,
+				  const char *prog, int flags)
+{
+	char *hostandport, *path;
+	struct child_process *conn;
+	enum protocol protocol;
+	enum protocol_version version = get_protocol_version_config();
+
+	/*
+	 * NEEDSWORK: If we are trying to use protocol v2 and we are planning
+	 * to perform a push, then fallback to v0 since the client doesn't know
+	 * how to push yet using v2.
+	 */
+	if (version == protocol_v2 && !strcmp("git-receive-pack", prog))
+		version = protocol_v0;
+
+	/* Without this we cannot rely on waitpid() to tell
+	 * what happened to our children.
+	 */
+	signal(SIGCHLD, SIG_DFL);
+
+	protocol = parse_connect_url(url, &hostandport, &path);
+	if ((flags & CONNECT_DIAG_URL) && (protocol != PROTO_SSH)) {
+		printf("Diag: url=%s\n", url ? url : "NULL");
+		printf("Diag: protocol=%s\n", prot_name(protocol));
+		printf("Diag: hostandport=%s\n", hostandport ? hostandport : "NULL");
+		printf("Diag: path=%s\n", path ? path : "NULL");
+		conn = NULL;
+	} else if (protocol == PROTO_GIT) {
+		conn = git_connect_git(fd, hostandport, path, prog, version, flags);
+		conn->trace2_child_class = "transport/git";
+	} else {
+		struct strbuf cmd = STRBUF_INIT;
+		const char *const *var;
+
+		conn = xmalloc(sizeof(*conn));
+		child_process_init(conn);
+
+		if (looks_like_command_line_option(path))
+			die(_("strange pathname '%s' blocked"), path);
+
+		strbuf_addstr(&cmd, prog);
+		strbuf_addch(&cmd, ' ');
+		sq_quote_buf(&cmd, path);
+
+		/* remove repo-local variables from the environment */
+		for (var = local_repo_env; *var; var++)
+			argv_array_push(&conn->env_array, *var);
+
+		conn->use_shell = 1;
+		conn->in = conn->out = -1;
+		if (protocol == PROTO_SSH) {
+			char *ssh_host = hostandport;
+			const char *port = NULL;
+			transport_check_allowed("ssh");
+			get_host_and_port(&ssh_host, &port);
+
+			if (!port)
+				port = get_port(ssh_host);
+
+			if (flags & CONNECT_DIAG_URL) {
+				printf("Diag: url=%s\n", url ? url : "NULL");
+				printf("Diag: protocol=%s\n", prot_name(protocol));
+				printf("Diag: userandhost=%s\n", ssh_host ? ssh_host : "NULL");
+				printf("Diag: port=%s\n", port ? port : "NONE");
+				printf("Diag: path=%s\n", path ? path : "NULL");
+
+				free(hostandport);
+				free(path);
+				free(conn);
+				strbuf_release(&cmd);
+				return NULL;
+			}
+			conn->trace2_child_class = "transport/ssh";
+			fill_ssh_args(conn, ssh_host, port, version, flags);
+		} else {
+			transport_check_allowed("file");
+			conn->trace2_child_class = "transport/file";
+			if (version > 0) {
+				argv_array_pushf(&conn->env_array, GIT_PROTOCOL_ENVIRONMENT "=version=%d",
+						 version);
+			}
+		}
+		argv_array_push(&conn->args, cmd.buf);
+
+		if (start_command(conn))
+			die(_("unable to fork"));
+
+		fd[0] = conn->out; /* read from child's stdout */
+		fd[1] = conn->in;  /* write to child's stdin */
+		strbuf_release(&cmd);
+	}
+	free(hostandport);
+	free(path);
+	return conn;
+}
+
+int finish_connect(struct child_process *conn)
+{
+	int code;
+	if (!conn || git_connection_is_socket(conn))
+		return 0;
+
+	code = finish_command(conn);
+	free(conn);
+	return code;
+}