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

1 files changed, 108 insertions, 29 deletions

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;