Merge branch 'kf/http-proxy-auth-methods'

New http.proxyAuthMethod configuration variable can be used to
specify what authentication method to use, as a way to work around
proxies that do not give error response expected by libcurl when
CURLAUTH_ANY is used.  Also, the codepath for proxy authentication
has been taught to use credential API to store the authentication
material in user's keyrings.

* kf/http-proxy-auth-methods:
  http: use credential API to handle proxy authentication
  http: allow selection of proxy authentication method

6 files changed, 181 insertions, 6 deletions

diff --git a/Documentation/config.txt b/Documentation/config.txt
index 877cbc875e..02bcde6bb5 100644
--- a/Documentation/config.txt
+++ b/Documentation/config.txt
@@ -1610,9 +1610,34 @@ help.htmlPath::
 
 http.proxy::
 	Override the HTTP proxy, normally configured using the 'http_proxy',
-	'https_proxy', and 'all_proxy' environment variables (see
-	`curl(1)`).  This can be overridden on a per-remote basis; see
-	remote.<name>.proxy
+	'https_proxy', and 'all_proxy' environment variables (see `curl(1)`). In
+	addition to the syntax understood by curl, it is possible to specify a
+	proxy string with a user name but no password, in which case git will
+	attempt to acquire one in the same way it does for other credentials. See
+	linkgit:gitcredentials[7] for more information. The syntax thus is
+	'[protocol://][user[:password]@]proxyhost[:port]'. This can be overridden
+	on a per-remote basis; see remote.<name>.proxy
+
+http.proxyAuthMethod::
+	Set the method with which to authenticate against the HTTP proxy. This
+	only takes effect if the configured proxy string contains a user name part
+	(i.e. is of the form 'user@host' or 'user@host:port'). This can be
+	overridden on a per-remote basis; see `remote.<name>.proxyAuthMethod`.
+	Both can be overridden by the 'GIT_HTTP_PROXY_AUTHMETHOD' environment
+	variable.  Possible values are:
++
+--
+* `anyauth` - Automatically pick a suitable authentication method. It is
+  assumed that the proxy answers an unauthenticated request with a 407
+  status code and one or more Proxy-authenticate headers with supported
+  authentication methods. This is the default.
+* `basic` - HTTP Basic authentication
+* `digest` - HTTP Digest authentication; this prevents the password from being
+  transmitted to the proxy in clear text
+* `negotiate` - GSS-Negotiate authentication (compare the --negotiate option
+  of `curl(1)`)
+* `ntlm` - NTLM authentication (compare the --ntlm option of `curl(1)`)
+--
 
 http.cookieFile::
 	File containing previously stored cookie lines which should be used
@@ -2423,6 +2448,11 @@ remote.<name>.proxy::
 	the proxy to use for that remote.  Set to the empty string to
 	disable proxying for that remote.
 
+remote.<name>.proxyAuthMethod::
+	For remotes that require curl (http, https and ftp), the method to use for
+	authenticating against the proxy in use (probably set in
+	`remote.<name>.proxy`). See `http.proxyAuthMethod`.
+
 remote.<name>.fetch::
 	The default set of "refspec" for linkgit:git-fetch[1]. See
 	linkgit:git-fetch[1].
diff --git a/Documentation/technical/api-remote.txt b/Documentation/technical/api-remote.txt
index 2cfdd224a8..f10941b2e8 100644
--- a/Documentation/technical/api-remote.txt
+++ b/Documentation/technical/api-remote.txt
@@ -51,6 +51,10 @@ struct remote
 
 	The proxy to use for curl (http, https, ftp, etc.) URLs.
 
+`http_proxy_authmethod`::
+
+	The method used for authenticating against `http_proxy`.
+
 struct remotes can be found by name with remote_get(), and iterated
 through with for_each_remote(). remote_get(NULL) will return the
 default remote, given the current branch and configuration.
diff --git a/http.c b/http.c
index 0da9e66398..dfc53c1e25 100644
--- a/http.c
+++ b/http.c
@@ -62,6 +62,26 @@ static long curl_low_speed_limit = -1;
 static long curl_low_speed_time = -1;
 static int curl_ftp_no_epsv;
 static const char *curl_http_proxy;
+static const char *http_proxy_authmethod;
+static struct {
+	const char *name;
+	long curlauth_param;
+} proxy_authmethods[] = {
+	{ "basic", CURLAUTH_BASIC },
+	{ "digest", CURLAUTH_DIGEST },
+	{ "negotiate", CURLAUTH_GSSNEGOTIATE },
+	{ "ntlm", CURLAUTH_NTLM },
+#ifdef LIBCURL_CAN_HANDLE_AUTH_ANY
+	{ "anyauth", CURLAUTH_ANY },
+#endif
+	/*
+	 * CURLAUTH_DIGEST_IE has no corresponding command-line option in
+	 * curl(1) and is not included in CURLAUTH_ANY, so we leave it out
+	 * here, too
+	 */
+};
+static struct credential proxy_auth = CREDENTIAL_INIT;
+static const char *curl_proxyuserpwd;
 static const char *curl_cookie_file;
 static int curl_save_cookies;
 struct credential http_auth = CREDENTIAL_INIT;
@@ -159,6 +179,9 @@ static void finish_active_slot(struct active_request_slot *slot)
 #else
 		slot->results->auth_avail = 0;
 #endif
+
+		curl_easy_getinfo(slot->curl, CURLINFO_HTTP_CONNECTCODE,
+			&slot->results->http_connectcode);
 	}
 
 	/* Run callback if appropriate */
@@ -256,6 +279,9 @@ static int http_options(const char *var, const char *value, void *cb)
 	if (!strcmp("http.proxy", var))
 		return git_config_string(&curl_http_proxy, var, value);
 
+	if (!strcmp("http.proxyauthmethod", var))
+		return git_config_string(&http_proxy_authmethod, var, value);
+
 	if (!strcmp("http.cookiefile", var))
 		return git_config_string(&curl_cookie_file, var, value);
 	if (!strcmp("http.savecookies", var)) {
@@ -304,6 +330,64 @@ static void init_curl_http_auth(CURL *result)
 #endif
 }
 
+/* *var must be free-able */
+static void var_override(const char **var, char *value)
+{
+	if (value) {
+		free((void *)*var);
+		*var = xstrdup(value);
+	}
+}
+
+static void set_proxyauth_name_password(CURL *result)
+{
+#if LIBCURL_VERSION_NUM >= 0x071301
+		curl_easy_setopt(result, CURLOPT_PROXYUSERNAME,
+			proxy_auth.username);
+		curl_easy_setopt(result, CURLOPT_PROXYPASSWORD,
+			proxy_auth.password);
+#else
+		struct strbuf s = STRBUF_INIT;
+
+		strbuf_addstr_urlencode(&s, proxy_auth.username, 1);
+		strbuf_addch(&s, ':');
+		strbuf_addstr_urlencode(&s, proxy_auth.password, 1);
+		curl_proxyuserpwd = strbuf_detach(&s, NULL);
+		curl_easy_setopt(result, CURLOPT_PROXYUSERPWD, curl_proxyuserpwd);
+#endif
+}
+
+static void init_curl_proxy_auth(CURL *result)
+{
+	if (proxy_auth.username) {
+		if (!proxy_auth.password)
+			credential_fill(&proxy_auth);
+		set_proxyauth_name_password(result);
+	}
+
+	var_override(&http_proxy_authmethod, getenv("GIT_HTTP_PROXY_AUTHMETHOD"));
+
+#if LIBCURL_VERSION_NUM >= 0x070a07 /* CURLOPT_PROXYAUTH and CURLAUTH_ANY */
+	if (http_proxy_authmethod) {
+		int i;
+		for (i = 0; i < ARRAY_SIZE(proxy_authmethods); i++) {
+			if (!strcmp(http_proxy_authmethod, proxy_authmethods[i].name)) {
+				curl_easy_setopt(result, CURLOPT_PROXYAUTH,
+						proxy_authmethods[i].curlauth_param);
+				break;
+			}
+		}
+		if (i == ARRAY_SIZE(proxy_authmethods)) {
+			warning("unsupported proxy authentication method %s: using anyauth",
+					http_proxy_authmethod);
+			curl_easy_setopt(result, CURLOPT_PROXYAUTH, CURLAUTH_ANY);
+		}
+	}
+	else
+		curl_easy_setopt(result, CURLOPT_PROXYAUTH, CURLAUTH_ANY);
+#endif
+}
+
 static int has_cert_password(void)
 {
 	if (ssl_cert == NULL || ssl_cert_password_required != 1)
@@ -462,6 +546,31 @@ static CURL *get_curl_handle(void)
 		curl_easy_setopt(result, CURLOPT_USE_SSL, CURLUSESSL_TRY);
 #endif
 
+	/*
+	 * CURL also examines these variables as a fallback; but we need to query
+	 * them here in order to decide whether to prompt for missing password (cf.
+	 * init_curl_proxy_auth()).
+	 *
+	 * Unlike many other common environment variables, these are historically
+	 * lowercase only. It appears that CURL did not know this and implemented
+	 * only uppercase variants, which was later corrected to take both - with
+	 * the exception of http_proxy, which is lowercase only also in CURL. As
+	 * the lowercase versions are the historical quasi-standard, they take
+	 * precedence here, as in CURL.
+	 */
+	if (!curl_http_proxy) {
+		if (!strcmp(http_auth.protocol, "https")) {
+			var_override(&curl_http_proxy, getenv("HTTPS_PROXY"));
+			var_override(&curl_http_proxy, getenv("https_proxy"));
+		} else {
+			var_override(&curl_http_proxy, getenv("http_proxy"));
+		}
+		if (!curl_http_proxy) {
+			var_override(&curl_http_proxy, getenv("ALL_PROXY"));
+			var_override(&curl_http_proxy, getenv("all_proxy"));
+		}
+	}
+
 	if (curl_http_proxy) {
 		curl_easy_setopt(result, CURLOPT_PROXY, curl_http_proxy);
 #if LIBCURL_VERSION_NUM >= 0x071800
@@ -475,10 +584,18 @@ static CURL *get_curl_handle(void)
 			curl_easy_setopt(result,
 				CURLOPT_PROXYTYPE, CURLPROXY_SOCKS4);
 #endif
+		if (strstr(curl_http_proxy, "://"))
+			credential_from_url(&proxy_auth, curl_http_proxy);
+		else {
+			struct strbuf url = STRBUF_INIT;
+			strbuf_addf(&url, "http://%s", curl_http_proxy);
+			credential_from_url(&proxy_auth, url.buf);
+			strbuf_release(&url);
+		}
+
+		curl_easy_setopt(result, CURLOPT_PROXY, proxy_auth.host);
 	}
-#if LIBCURL_VERSION_NUM >= 0x070a07
-	curl_easy_setopt(result, CURLOPT_PROXYAUTH, CURLAUTH_ANY);
-#endif
+	init_curl_proxy_auth(result);
 
 	set_curl_keepalive(result);
 
@@ -519,6 +636,9 @@ void http_init(struct remote *remote, const char *url, int proactive_auth)
 	if (remote && remote->http_proxy)
 		curl_http_proxy = xstrdup(remote->http_proxy);
 
+	if (remote)
+		var_override(&http_proxy_authmethod, remote->http_proxy_authmethod);
+
 	pragma_header = curl_slist_append(pragma_header, "Pragma: no-cache");
 	no_pragma_header = curl_slist_append(no_pragma_header, "Pragma:");
 
@@ -617,6 +737,18 @@ void http_cleanup(void)
 		curl_http_proxy = NULL;
 	}
 
+	if (proxy_auth.password) {
+		memset(proxy_auth.password, 0, strlen(proxy_auth.password));
+		free(proxy_auth.password);
+		proxy_auth.password = NULL;
+	}
+
+	free((void *)curl_proxyuserpwd);
+	curl_proxyuserpwd = NULL;
+
+	free((void *)http_proxy_authmethod);
+	http_proxy_authmethod = NULL;
+
 	if (cert_auth.password != NULL) {
 		memset(cert_auth.password, 0, strlen(cert_auth.password));
 		free(cert_auth.password);
@@ -946,6 +1078,8 @@ static int handle_curl_result(struct slot_results *results)
 
 	if (results->curl_result == CURLE_OK) {
 		credential_approve(&http_auth);
+		if (proxy_auth.password)
+			credential_approve(&proxy_auth);
 		return HTTP_OK;
 	} else if (missing_target(results))
 		return HTTP_MISSING_TARGET;
@@ -960,6 +1094,8 @@ static int handle_curl_result(struct slot_results *results)
 			return HTTP_REAUTH;
 		}
 	} else {
+		if (results->http_connectcode == 407)
+			credential_reject(&proxy_auth);
 #if LIBCURL_VERSION_NUM >= 0x070c00
 		if (!curl_errorstr[0])
 			strlcpy(curl_errorstr,
diff --git a/http.h b/http.h
index 4f97b60b5c..f83cfa6868 100644
--- a/http.h
+++ b/http.h
@@ -54,6 +54,7 @@ struct slot_results {
 	CURLcode curl_result;
 	long http_code;
 	long auth_avail;
+	long http_connectcode;
 };
 
 struct active_request_slot {
diff --git a/remote.c b/remote.c
index 7d61dabebb..35940a5602 100644
--- a/remote.c
+++ b/remote.c
@@ -428,6 +428,9 @@ static int handle_config(const char *key, const char *value, void *cb)
 	} else if (!strcmp(subkey, ".proxy")) {
 		return git_config_string((const char **)&remote->http_proxy,
 					 key, value);
+	} else if (!strcmp(subkey, ".proxyauthmethod")) {
+		return git_config_string((const char **)&remote->http_proxy_authmethod,
+					 key, value);
 	} else if (!strcmp(subkey, ".vcs")) {
 		return git_config_string(&remote->foreign_vcs, key, value);
 	}
diff --git a/remote.h b/remote.h
index 4a039bae0b..4fd7a0f9b2 100644
--- a/remote.h
+++ b/remote.h
@@ -54,6 +54,7 @@ struct remote {
 	 * for curl remotes only
 	 */
 	char *http_proxy;
+	char *http_proxy_authmethod;
 };
 
 struct remote *remote_get(const char *name);