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[PATCH 2/2] http: use credential API to handle proxy authentication

From
KFKnut Franke <k.franke@science-computing.de>
Date
Nov 4, 2015, 09:13 UTC
Message-ID
<1446628405-8070-3-git-send-email-k.franke@science-computing.de>
In-Reply-To
<1446628405-8070-1-git-send-email-k.franke@science-computing.de>

Currently, the only way to pass proxy credentials to curl is by including them in the proxy URL. Usually, this means they will end up on disk unencrypted, one way or another (by inclusion in ~/.gitconfig, shell profile or history). Since proxy authentication often uses a domain user, credentials can be security sensitive; therefore, a safer way of passing credentials is desirable.

If the configured proxy contains a username but not a password, query the credential API for one. Also, make sure we approve/reject proxy credentials properly.

For consistency reasons, add parsing of http_proxy/https_proxy/all_proxy environment variables, which would otherwise be evaluated as a fallback by curl. Without this, we would have different semantics for git configuration and environment variables.

Signed-off-by: Knut Franke <k.franke@science-computing.de>
Helped-by: Junio C Hamano <gitster@pobox.com>
Helped-by: Eric Sunshine <sunshine@sunshineco.com>
---
 Documentation/config.txt | 10 +++++--
 http.c                   | 72 +++++++++++++++++++++++++++++++++++++++++++++++-
 http.h                   |  1 +
 3 files changed, 79 insertions(+), 4 deletions(-)
diff --git a/Documentation/config.txt b/Documentation/config.txt
index 4ad7f74..320ce9a 100644
--- a/Documentation/config.txt
+++ b/Documentation/config.txt
@@ -1593,9 +1593,13 @@ 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
diff --git a/http.c b/http.c
index a786802..714a59a 100644
--- a/http.c
+++ b/http.c
@@ -81,6 +81,8 @@ static struct {
 	 * 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;
@@ -178,6 +180,9 @@ 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 */
@@ -337,6 +342,24 @@ static void var_override(const char **var, char *value)
 
 static void init_curl_proxy_auth(CURL *result)
 {
+	if (proxy_auth.username) {
+		struct strbuf s = STRBUF_INIT;
+		if (!proxy_auth.password)
+			credential_fill(&proxy_auth);
+#if LIBCURL_VERSION_NUM >= 0x071301
+		curl_easy_setopt(result, CURLOPT_PROXYUSERNAME,
+			proxy_auth.username);
+		curl_easy_setopt(result, CURLOPT_PROXYPASSWORD,
+			proxy_auth.password);
+#else
+		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
+	}
+
 	var_override(&http_proxy_authmethod, getenv("GIT_HTTP_PROXY_AUTHMETHOD"));
 
 #if LIBCURL_VERSION_NUM >= 0x070a07 /* CURLOPT_PROXYAUTH and CURLAUTH_ANY */
@@ -518,8 +541,42 @@ 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 (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);
 	}
 	init_curl_proxy_auth(result);
 
@@ -663,6 +720,15 @@ 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;
 
@@ -994,6 +1060,8 @@ 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;
@@ -1008,6 +1076,8 @@ 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 49afe39..7352a9e 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 {

-- 
2.3.7

-- 
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Gerd-Lothar Leonhart
Vorstand/Board of Management:
Dr. Bernd Finkbeiner, Dr. Arno Steitz
Vorsitzender des Aufsichtsrats/
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Previous: Junio C HamanoNext: Eric Sunshine
Message 29 of 34 in “http: allow selection of proxy authentication method”
  1. 1/2 http: allow selection of proxy authentication methodKnut Franke, Oct 26, 2015
  2. 2/2 http: use credential API to handle proxy authenticationKnut Franke, Oct 26, 2015
  3. Junio C HamanoOct 26, 2015
  4. Knut FrankeOct 27, 2015
  5. http proxy authentication improvementsKnut Franke, Oct 28, 2015
  6. 1/2 http: allow selection of proxy authentication methodKnut Franke, Oct 28, 2015
  7. Junio C HamanoOct 28, 2015
  8. Junio C HamanoOct 28, 2015
  9. Knut FrankeOct 30, 2015
  10. Junio C HamanoOct 30, 2015
  11. Eric SunshineOct 28, 2015
  12. 2/2 http: use credential API to handle proxy authenticationKnut Franke, Oct 28, 2015
  13. Eric SunshineOct 28, 2015
  14. Knut FrankeOct 30, 2015
  15. Junio C HamanoOct 30, 2015
  16. Eric SunshineOct 30, 2015
  17. 0/2 Knut Franke, Nov 2, 2015
  18. 1/2 http: allow selection of proxy authentication methodKnut Franke, Nov 2, 2015
  19. Junio C HamanoNov 2, 2015
  20. Knut FrankeNov 3, 2015
  21. Junio C HamanoNov 3, 2015
  22. 2/2 http: use credential API to handle proxy authenticationKnut Franke, Nov 2, 2015
  23. Junio C HamanoNov 2, 2015
  24. Knut FrankeNov 3, 2015
  25. Eric SunshineNov 3, 2015
  26. 0/2 Knut Franke, Nov 4, 2015
  27. 1/2 http: allow selection of proxy authentication methodKnut Franke, Nov 4, 2015
  28. Junio C HamanoNov 4, 2015
  29. 2/2 http: use credential API to handle proxy authenticationKnut Franke, Nov 4, 2015
  30. Eric SunshineNov 4, 2015
  31. Junio C HamanoNov 4, 2015
  32. Jeff KingNov 5, 2015
  33. Knut FrankeNov 5, 2015
  34. Jeff KingNov 5, 2015

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