Merge branch 'jk/http-auth-redirects'

Handle the case where http transport gets redirected during the
authorization request better.

* jk/http-auth-redirects:
  http.c: Spell the null pointer as NULL
  remote-curl: rewrite base url from info/refs redirects
  remote-curl: store url as a strbuf
  remote-curl: make refs_url a strbuf
  http: update base URLs when we see redirects
  http: provide effective url to callers
  http: hoist credential request out of handle_curl_result
  http: refactor options to http_get_*
  http_request: factor out curlinfo_strbuf
  http_get_file: style fixes

7 files changed, 191 insertions, 65 deletions

diff --git a/http-push.c b/http-push.c
index 69200baf76..34cb70f90e 100644
--- a/http-push.c
+++ b/http-push.c
@@ -1542,7 +1542,7 @@ static int remote_exists(const char *path)
 
 	sprintf(url, "%s%s", repo->url, path);
 
-	switch (http_get_strbuf(url, NULL, NULL, 0)) {
+	switch (http_get_strbuf(url, NULL, NULL)) {
 	case HTTP_OK:
 		ret = 1;
 		break;
@@ -1566,7 +1566,7 @@ static void fetch_symref(const char *path, char **symref, unsigned char *sha1)
 	url = xmalloc(strlen(repo->url) + strlen(path) + 1);
 	sprintf(url, "%s%s", repo->url, path);
 
-	if (http_get_strbuf(url, NULL, &buffer, 0) != HTTP_OK)
+	if (http_get_strbuf(url, &buffer, NULL) != HTTP_OK)
 		die("Couldn't get %s for remote symref\n%s", url,
 		    curl_errorstr);
 	free(url);
diff --git a/http.c b/http.c
index 0ddb164a6f..bcf54aa35f 100644
--- a/http.c
+++ b/http.c
@@ -47,7 +47,7 @@ static int curl_ftp_no_epsv;
 static const char *curl_http_proxy;
 static const char *curl_cookie_file;
 static int curl_save_cookies;
-static struct credential http_auth = CREDENTIAL_INIT;
+struct credential http_auth = CREDENTIAL_INIT;
 static int http_proactive_auth;
 static const char *user_agent;
 
@@ -861,7 +861,6 @@ int handle_curl_result(struct slot_results *results)
 			credential_reject(&http_auth);
 			return HTTP_NOAUTH;
 		} else {
-			credential_fill(&http_auth);
 			return HTTP_REAUTH;
 		}
 	} else {
@@ -875,12 +874,25 @@ int handle_curl_result(struct slot_results *results)
 	}
 }
 
+static CURLcode curlinfo_strbuf(CURL *curl, CURLINFO info, struct strbuf *buf)
+{
+	char *ptr;
+	CURLcode ret;
+
+	strbuf_reset(buf);
+	ret = curl_easy_getinfo(curl, info, &ptr);
+	if (!ret && ptr)
+		strbuf_addstr(buf, ptr);
+	return ret;
+}
+
 /* http_request() targets */
 #define HTTP_REQUEST_STRBUF	0
 #define HTTP_REQUEST_FILE	1
 
-static int http_request(const char *url, struct strbuf *type,
-			void *result, int target, int options)
+static int http_request(const char *url,
+			void *result, int target,
+			const struct http_get_options *options)
 {
 	struct active_request_slot *slot;
 	struct slot_results results;
@@ -913,9 +925,9 @@ static int http_request(const char *url, struct strbuf *type,
 	}
 
 	strbuf_addstr(&buf, "Pragma:");
-	if (options & HTTP_NO_CACHE)
+	if (options && options->no_cache)
 		strbuf_addstr(&buf, " no-cache");
-	if (options & HTTP_KEEP_ERROR)
+	if (options && options->keep_error)
 		curl_easy_setopt(slot->curl, CURLOPT_FAILONERROR, 0);
 
 	headers = curl_slist_append(headers, buf.buf);
@@ -933,13 +945,13 @@ static int http_request(const char *url, struct strbuf *type,
 		ret = HTTP_START_FAILED;
 	}
 
-	if (type) {
-		char *t;
-		strbuf_reset(type);
-		curl_easy_getinfo(slot->curl, CURLINFO_CONTENT_TYPE, &t);
-		if (t)
-			strbuf_addstr(type, t);
-	}
+	if (options && options->content_type)
+		curlinfo_strbuf(slot->curl, CURLINFO_CONTENT_TYPE,
+				options->content_type);
+
+	if (options && options->effective_url)
+		curlinfo_strbuf(slot->curl, CURLINFO_EFFECTIVE_URL,
+				options->effective_url);
 
 	curl_slist_free_all(headers);
 	strbuf_release(&buf);
@@ -947,12 +959,71 @@ static int http_request(const char *url, struct strbuf *type,
 	return ret;
 }
 
+/*
+ * Update the "base" url to a more appropriate value, as deduced by
+ * redirects seen when requesting a URL starting with "url".
+ *
+ * The "asked" parameter is a URL that we asked curl to access, and must begin
+ * with "base".
+ *
+ * The "got" parameter is the URL that curl reported to us as where we ended
+ * up.
+ *
+ * Returns 1 if we updated the base url, 0 otherwise.
+ *
+ * Our basic strategy is to compare "base" and "asked" to find the bits
+ * specific to our request. We then strip those bits off of "got" to yield the
+ * new base. So for example, if our base is "http://example.com/foo.git",
+ * and we ask for "http://example.com/foo.git/info/refs", we might end up
+ * with "https://other.example.com/foo.git/info/refs". We would want the
+ * new URL to become "https://other.example.com/foo.git".
+ *
+ * Note that this assumes a sane redirect scheme. It's entirely possible
+ * in the example above to end up at a URL that does not even end in
+ * "info/refs".  In such a case we simply punt, as there is not much we can
+ * do (and such a scheme is unlikely to represent a real git repository,
+ * which means we are likely about to abort anyway).
+ */
+static int update_url_from_redirect(struct strbuf *base,
+				    const char *asked,
+				    const struct strbuf *got)
+{
+	const char *tail;
+	size_t tail_len;
+
+	if (!strcmp(asked, got->buf))
+		return 0;
+
+	if (prefixcmp(asked, base->buf))
+		die("BUG: update_url_from_redirect: %s is not a superset of %s",
+		    asked, base->buf);
+
+	tail = asked + base->len;
+	tail_len = strlen(tail);
+
+	if (got->len < tail_len ||
+	    strcmp(tail, got->buf + got->len - tail_len))
+		return 0; /* insane redirect scheme */
+
+	strbuf_reset(base);
+	strbuf_add(base, got->buf, got->len - tail_len);
+	return 1;
+}
+
 static int http_request_reauth(const char *url,
-			       struct strbuf *type,
 			       void *result, int target,
-			       int options)
+			       struct http_get_options *options)
 {
-	int ret = http_request(url, type, result, target, options);
+	int ret = http_request(url, result, target, options);
+
+	if (options && options->effective_url && options->base_url) {
+		if (update_url_from_redirect(options->base_url,
+					     url, options->effective_url)) {
+			credential_from_url(&http_auth, options->base_url->buf);
+			url = options->effective_url->buf;
+		}
+	}
+
 	if (ret != HTTP_REAUTH)
 		return ret;
 
@@ -962,7 +1033,7 @@ static int http_request_reauth(const char *url,
 	 * making our next request. We only know how to do this for
 	 * the strbuf case, but that is enough to satisfy current callers.
 	 */
-	if (options & HTTP_KEEP_ERROR) {
+	if (options && options->keep_error) {
 		switch (target) {
 		case HTTP_REQUEST_STRBUF:
 			strbuf_reset(result);
@@ -971,15 +1042,17 @@ static int http_request_reauth(const char *url,
 			die("BUG: HTTP_KEEP_ERROR is only supported with strbufs");
 		}
 	}
-	return http_request(url, type, result, target, options);
+
+	credential_fill(&http_auth);
+
+	return http_request(url, result, target, options);
 }
 
 int http_get_strbuf(const char *url,
-		    struct strbuf *type,
-		    struct strbuf *result, int options)
+		    struct strbuf *result,
+		    struct http_get_options *options)
 {
-	return http_request_reauth(url, type, result,
-				   HTTP_REQUEST_STRBUF, options);
+	return http_request_reauth(url, result, HTTP_REQUEST_STRBUF, options);
 }
 
 /*
@@ -988,7 +1061,8 @@ int http_get_strbuf(const char *url,
  * If a previous interrupted download is detected (i.e. a previous temporary
  * file is still around) the download is resumed.
  */
-static int http_get_file(const char *url, const char *filename, int options)
+static int http_get_file(const char *url, const char *filename,
+			 struct http_get_options *options)
 {
 	int ret;
 	struct strbuf tmpfile = STRBUF_INIT;
@@ -996,16 +1070,16 @@ static int http_get_file(const char *url, const char *filename, int options)
 
 	strbuf_addf(&tmpfile, "%s.temp", filename);
 	result = fopen(tmpfile.buf, "a");
-	if (! result) {
+	if (!result) {
 		error("Unable to open local file %s", tmpfile.buf);
 		ret = HTTP_ERROR;
 		goto cleanup;
 	}
 
-	ret = http_request_reauth(url, NULL, result, HTTP_REQUEST_FILE, options);
+	ret = http_request_reauth(url, result, HTTP_REQUEST_FILE, options);
 	fclose(result);
 
-	if ((ret == HTTP_OK) && move_temp_to_file(tmpfile.buf, filename))
+	if (ret == HTTP_OK && move_temp_to_file(tmpfile.buf, filename))
 		ret = HTTP_ERROR;
 cleanup:
 	strbuf_release(&tmpfile);
@@ -1014,12 +1088,15 @@ cleanup:
 
 int http_fetch_ref(const char *base, struct ref *ref)
 {
+	struct http_get_options options = {0};
 	char *url;
 	struct strbuf buffer = STRBUF_INIT;
 	int ret = -1;
 
+	options.no_cache = 1;
+
 	url = quote_ref_url(base, ref->name);
-	if (http_get_strbuf(url, NULL, &buffer, HTTP_NO_CACHE) == HTTP_OK) {
+	if (http_get_strbuf(url, &buffer, &options) == HTTP_OK) {
 		strbuf_rtrim(&buffer);
 		if (buffer.len == 40)
 			ret = get_sha1_hex(buffer.buf, ref->old_sha1);
@@ -1050,7 +1127,7 @@ static char *fetch_pack_index(unsigned char *sha1, const char *base_url)
 	strbuf_addf(&buf, "%s.temp", sha1_pack_index_name(sha1));
 	tmp = strbuf_detach(&buf, NULL);
 
-	if (http_get_file(url, tmp, 0) != HTTP_OK) {
+	if (http_get_file(url, tmp, NULL) != HTTP_OK) {
 		error("Unable to get pack index %s", url);
 		free(tmp);
 		tmp = NULL;
@@ -1103,6 +1180,7 @@ add_pack:
 
 int http_get_info_packs(const char *base_url, struct packed_git **packs_head)
 {
+	struct http_get_options options = {0};
 	int ret = 0, i = 0;
 	char *url, *data;
 	struct strbuf buf = STRBUF_INIT;
@@ -1112,7 +1190,8 @@ int http_get_info_packs(const char *base_url, struct packed_git **packs_head)
 	strbuf_addstr(&buf, "objects/info/packs");
 	url = strbuf_detach(&buf, NULL);
 
-	ret = http_get_strbuf(url, NULL, &buf, HTTP_NO_CACHE);
+	options.no_cache = 1;
+	ret = http_get_strbuf(url, &buf, &options);
 	if (ret != HTTP_OK)
 		goto cleanup;
 
diff --git a/http.h b/http.h
index d77c1b54f2..12ca5c892d 100644
--- a/http.h
+++ b/http.h
@@ -102,6 +102,7 @@ extern void http_cleanup(void);
 extern int active_requests;
 extern int http_is_verbose;
 extern size_t http_post_buffer;
+extern struct credential http_auth;
 
 extern char curl_errorstr[CURL_ERROR_SIZE];
 
@@ -125,11 +126,30 @@ extern void append_remote_object_url(struct strbuf *buf, const char *url,
 extern char *get_remote_object_url(const char *url, const char *hex,
 				   int only_two_digit_prefix);
 
-/* Options for http_request_*() */
-#define HTTP_NO_CACHE		1
-#define HTTP_KEEP_ERROR		2
+/* Options for http_get_*() */
+struct http_get_options {
+	unsigned no_cache:1,
+		 keep_error:1;
+
+	/* If non-NULL, returns the content-type of the response. */
+	struct strbuf *content_type;
+
+	/*
+	 * If non-NULL, returns the URL we ended up at, including any
+	 * redirects we followed.
+	 */
+	struct strbuf *effective_url;
+
+	/*
+	 * If both base_url and effective_url are non-NULL, the base URL will
+	 * be munged to reflect any redirections going from the requested url
+	 * to effective_url. See the definition of update_url_from_redirect
+	 * for details.
+	 */
+	struct strbuf *base_url;
+};
 
-/* Return values for http_request_*() */
+/* Return values for http_get_*() */
 #define HTTP_OK			0
 #define HTTP_MISSING_TARGET	1
 #define HTTP_ERROR		2
@@ -142,7 +162,7 @@ extern char *get_remote_object_url(const char *url, const char *hex,
  *
  * If the result pointer is NULL, a HTTP HEAD request is made instead of GET.
  */
-int http_get_strbuf(const char *url, struct strbuf *content_type, struct strbuf *result, int options);
+int http_get_strbuf(const char *url, struct strbuf *result, struct http_get_options *options);
 
 extern int http_fetch_ref(const char *base, struct ref *ref);
 
diff --git a/remote-curl.c b/remote-curl.c
index b5ebe01800..c9b891adbf 100644
--- a/remote-curl.c
+++ b/remote-curl.c
@@ -9,9 +9,11 @@
 #include "string-list.h"
 #include "sideband.h"
 #include "argv-array.h"
+#include "credential.h"
 
 static struct remote *remote;
-static const char *url; /* always ends with a trailing slash */
+/* always ends with a trailing slash */
+static struct strbuf url = STRBUF_INIT;
 
 struct options {
 	int verbosity;
@@ -130,7 +132,8 @@ static struct ref *parse_info_refs(struct discovery *heads)
 			mid = &data[i];
 		if (data[i] == '\n') {
 			if (mid - start != 40)
-				die("%sinfo/refs not valid: is this a git repository?", url);
+				die("%sinfo/refs not valid: is this a git repository?",
+				    url.buf);
 			data[i] = 0;
 			ref_name = mid + 1;
 			ref = xmalloc(sizeof(struct ref) +
@@ -149,7 +152,7 @@ static struct ref *parse_info_refs(struct discovery *heads)
 	}
 
 	ref = alloc_ref("HEAD");
-	if (!http_fetch_ref(url, ref) &&
+	if (!http_fetch_ref(url.buf, ref) &&
 	    !resolve_remote_symref(ref, refs)) {
 		ref->next = refs;
 		refs = ref;
@@ -203,40 +206,47 @@ static struct discovery* discover_refs(const char *service, int for_push)
 	struct strbuf exp = STRBUF_INIT;
 	struct strbuf type = STRBUF_INIT;
 	struct strbuf buffer = STRBUF_INIT;
+	struct strbuf refs_url = STRBUF_INIT;
+	struct strbuf effective_url = STRBUF_INIT;
 	struct discovery *last = last_discovery;
-	char *refs_url;
 	int http_ret, maybe_smart = 0;
+	struct http_get_options options;
 
 	if (last && !strcmp(service, last->service))
 		return last;
 	free_discovery(last);
 
-	strbuf_addf(&buffer, "%sinfo/refs", url);
-	if ((!prefixcmp(url, "http://") || !prefixcmp(url, "https://")) &&
+	strbuf_addf(&refs_url, "%sinfo/refs", url.buf);
+	if ((!prefixcmp(url.buf, "http://") || !prefixcmp(url.buf, "https://")) &&
 	     git_env_bool("GIT_SMART_HTTP", 1)) {
 		maybe_smart = 1;
-		if (!strchr(url, '?'))
-			strbuf_addch(&buffer, '?');
+		if (!strchr(url.buf, '?'))
+			strbuf_addch(&refs_url, '?');
 		else
-			strbuf_addch(&buffer, '&');
-		strbuf_addf(&buffer, "service=%s", service);
+			strbuf_addch(&refs_url, '&');
+		strbuf_addf(&refs_url, "service=%s", service);
 	}
-	refs_url = strbuf_detach(&buffer, NULL);
 
-	http_ret = http_get_strbuf(refs_url, &type, &buffer,
-				   HTTP_NO_CACHE | HTTP_KEEP_ERROR);
+	memset(&options, 0, sizeof(options));
+	options.content_type = &type;
+	options.effective_url = &effective_url;
+	options.base_url = &url;
+	options.no_cache = 1;
+	options.keep_error = 1;
+
+	http_ret = http_get_strbuf(refs_url.buf, &buffer, &options);
 	switch (http_ret) {
 	case HTTP_OK:
 		break;
 	case HTTP_MISSING_TARGET:
 		show_http_message(&type, &buffer);
-		die("repository '%s' not found", url);
+		die("repository '%s' not found", url.buf);
 	case HTTP_NOAUTH:
 		show_http_message(&type, &buffer);
-		die("Authentication failed for '%s'", url);
+		die("Authentication failed for '%s'", url.buf);
 	default:
 		show_http_message(&type, &buffer);
-		die("unable to access '%s': %s", url, curl_errorstr);
+		die("unable to access '%s': %s", url.buf, curl_errorstr);
 	}
 
 	last= xcalloc(1, sizeof(*last_discovery));
@@ -277,9 +287,10 @@ static struct discovery* discover_refs(const char *service, int for_push)
 	else
 		last->refs = parse_info_refs(last);
 
-	free(refs_url);
+	strbuf_release(&refs_url);
 	strbuf_release(&exp);
 	strbuf_release(&type);
+	strbuf_release(&effective_url);
 	strbuf_release(&buffer);
 	last_discovery = last;
 	return last;
@@ -463,6 +474,8 @@ static int post_rpc(struct rpc_state *rpc)
 	if (large_request) {
 		do {
 			err = probe_rpc(rpc);
+			if (err == HTTP_REAUTH)
+				credential_fill(&http_auth);
 		} while (err == HTTP_REAUTH);
 		if (err != HTTP_OK)
 			return -1;
@@ -562,8 +575,10 @@ retry:
 	curl_easy_setopt(slot->curl, CURLOPT_FILE, rpc);
 
 	err = run_slot(slot);
-	if (err == HTTP_REAUTH && !large_request)
+	if (err == HTTP_REAUTH && !large_request) {
+		credential_fill(&http_auth);
 		goto retry;
+	}
 	if (err != HTTP_OK)
 		err = -1;
 
@@ -598,7 +613,7 @@ static int rpc_service(struct rpc_state *rpc, struct discovery *heads)
 	rpc->out = client.out;
 	strbuf_init(&rpc->result, 0);
 
-	strbuf_addf(&buf, "%s%s", url, svc);
+	strbuf_addf(&buf, "%s%s", url.buf, svc);
 	rpc->service_url = strbuf_detach(&buf, NULL);
 
 	strbuf_addf(&buf, "Content-Type: application/x-%s-request", svc);
@@ -650,7 +665,7 @@ static int fetch_dumb(int nr_heads, struct ref **to_fetch)
 	for (i = 0; i < nr_heads; i++)
 		targets[i] = xstrdup(sha1_to_hex(to_fetch[i]->old_sha1));
 
-	walker = get_http_walker(url);
+	walker = get_http_walker(url.buf);
 	walker->get_all = 1;
 	walker->get_tree = 1;
 	walker->get_history = 1;
@@ -697,7 +712,7 @@ static int fetch_git(struct discovery *heads,
 		depth_arg = strbuf_detach(&buf, NULL);
 		argv[argc++] = depth_arg;
 	}
-	argv[argc++] = url;
+	argv[argc++] = url.buf;
 	argv[argc++] = NULL;
 
 	for (i = 0; i < nr_heads; i++) {
@@ -795,7 +810,7 @@ static int push_dav(int nr_spec, char **specs)
 		argv[argc++] = "--dry-run";
 	if (options.verbosity > 1)
 		argv[argc++] = "--verbose";
-	argv[argc++] = url;
+	argv[argc++] = url.buf;
 	for (i = 0; i < nr_spec; i++)
 		argv[argc++] = specs[i];
 	argv[argc++] = NULL;
@@ -828,7 +843,7 @@ static int push_git(struct discovery *heads, int nr_spec, char **specs)
 	argv_array_push(&args, options.progress ? "--progress" : "--no-progress");
 	for_each_string_list_item(cas_option, &cas_options)
 		argv_array_push(&args, cas_option->string);
-	argv_array_push(&args, url);
+	argv_array_push(&args, url.buf);
 	for (i = 0; i < nr_spec; i++)
 		argv_array_push(&args, specs[i]);
 
@@ -909,14 +924,12 @@ int main(int argc, const char **argv)
 	remote = remote_get(argv[1]);
 
 	if (argc > 2) {
-		end_url_with_slash(&buf, argv[2]);
+		end_url_with_slash(&url, argv[2]);
 	} else {
-		end_url_with_slash(&buf, remote->url[0]);
+		end_url_with_slash(&url, remote->url[0]);
 	}
 
-	url = strbuf_detach(&buf, NULL);
-
-	http_init(remote, url, 0);
+	http_init(remote, url.buf, 0);
 
 	do {
 		if (strbuf_getline(&buf, stdin, '\n') == EOF) {
diff --git a/t/lib-httpd.sh b/t/lib-httpd.sh
index 54dbbfe5ce..ad8f1ef71e 100644
--- a/t/lib-httpd.sh
+++ b/t/lib-httpd.sh
@@ -204,7 +204,8 @@ set_askpass() {
 }
 
 expect_askpass() {
-	dest=$HTTPD_DEST
+	dest=$HTTPD_DEST${3+/$3}
+
 	{
 		case "$1" in
 		none)
diff --git a/t/lib-httpd/apache.conf b/t/lib-httpd/apache.conf
index 397c480401..3a03e8263d 100644
--- a/t/lib-httpd/apache.conf
+++ b/t/lib-httpd/apache.conf
@@ -110,6 +110,8 @@ ScriptAlias /broken_smart/ broken-smart-http.sh/
 RewriteEngine on
 RewriteRule ^/smart-redir-perm/(.*)$ /smart/$1 [R=301]
 RewriteRule ^/smart-redir-temp/(.*)$ /smart/$1 [R=302]
+RewriteRule ^/smart-redir-auth/(.*)$ /auth/smart/$1 [R=301]
+RewriteRule ^/smart-redir-limited/(.*)/info/refs$ /smart/$1/info/refs [R=301]
 
 <IfDefine SSL>
 LoadModule ssl_module modules/mod_ssl.so
diff --git a/t/t5551-http-fetch.sh b/t/t5551-http-fetch.sh
index 8196af19f6..fb16833f76 100755
--- a/t/t5551-http-fetch.sh
+++ b/t/t5551-http-fetch.sh
@@ -113,6 +113,10 @@ test_expect_success 'follow redirects (302)' '
 	git clone $HTTPD_URL/smart-redir-temp/repo.git --quiet repo-t
 '
 
+test_expect_success 'redirects re-root further requests' '
+	git clone $HTTPD_URL/smart-redir-limited/repo.git repo-redir-limited
+'
+
 test_expect_success 'clone from password-protected repository' '
 	echo two >expect &&
 	set_askpass user@host &&
@@ -146,6 +150,13 @@ test_expect_success 'no-op half-auth fetch does not require a password' '
 	expect_askpass none
 '
 
+test_expect_success 'redirects send auth to new location' '
+	set_askpass user@host &&
+	git -c credential.useHttpPath=true \
+	  clone $HTTPD_URL/smart-redir-auth/repo.git repo-redir-auth &&
+	expect_askpass both user@host auth/smart/repo.git
+'
+
 test_expect_success 'disable dumb http on server' '
 	git --git-dir="$HTTPD_DOCUMENT_ROOT_PATH/repo.git" \
 		config http.getanyfile false