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[PATCH v3] http: add custom hostname to IP address resolutions

From
Christian Couder <christian.couder@gmail.com>
Date
May 9, 2022, 15:38 UTC
Message-ID
<20220509153834.485871-1-chriscool@tuxfamily.org>
In-Reply-To
<20220504104601.136403-1-chriscool@tuxfamily.org>

Libcurl has a CURLOPT_RESOLVE easy option that allows the result of hostname resolution in the following format to be passed:

	[+]HOST:PORT:ADDRESS[,ADDRESS]

This way, redirects and everything operating against the HOST+PORT will use the provided ADDRESS(s).

The following format is also allowed to stop using hostname resolutions that have already been passed:

	-HOST:PORT

See https://curl.se/libcurl/c/CURLOPT_RESOLVE.html for more details.

Let's add a corresponding "http.curloptResolve" config option that takes advantage of CURLOPT_RESOLVE.

Each value configured for the "http.curloptResolve" key is passed "as is" to libcurl through CURLOPT_RESOLVE, so it should be in one of the above 2 formats. This keeps the implementation simple and makes us consistent with libcurl's CURLOPT_RESOLVE, and with curl's corresponding `--resolve` command line option.

The implementation uses CURLOPT_RESOLVE only in get_active_slot() which is called by all the HTTP request sending functions.

Signed-off-by: Christian Couder <chriscool@tuxfamily.org>
---
Changes since v2 are the following:
  - option renamed from "http.resolve" to "http.curloptResolve"
  - mention "libcurl" instead of "curl" in the commit message
  - mention "libculr" in the doc to make it easier to understand
    the new option name
Range diff:
1:  28c3bf9d02 ! 1:  3d689f8a6f http: add custom hostname to IP address resolutions
    @@ Commit message
         See https://curl.se/libcurl/c/CURLOPT_RESOLVE.html for
         more details.
     
    -    Let's add a corresponding "http.resolve" config option
    -    that takes advantage of CURLOPT_RESOLVE.
    +    Let's add a corresponding "http.curloptResolve" config
    +    option that takes advantage of CURLOPT_RESOLVE.
     
    -    Each value configured for the "http.resolve" key is
    -    passed "as is" to curl through CURLOPT_RESOLVE, so it
    -    should be in one of the above 2 formats. This keeps the
    -    implementation simple and makes us consistent with
    +    Each value configured for the "http.curloptResolve" key
    +    is passed "as is" to libcurl through CURLOPT_RESOLVE, so
    +    it should be in one of the above 2 formats. This keeps
    +    the implementation simple and makes us consistent with
         libcurl's CURLOPT_RESOLVE, and with curl's corresponding
         `--resolve` command line option.
     
    @@ Documentation/config/http.txt: http.version::
        - HTTP/2
        - HTTP/1.1
      
    -+http.resolve::
    -+  Hostname resolution information that will be used first when sending
    -+  HTTP requests.  This information should be in one of the following
    -+  formats:
    ++http.curloptResolve::
    ++  Hostname resolution information that will be used first by
    ++  libcurl when sending HTTP requests.  This information should
    ++  be in one of the following formats:
     +
     +  - [+]HOST:PORT:ADDRESS[,ADDRESS]
     +  - -HOST:PORT
    @@ http.c: static int http_options(const char *var, const char *value, void *cb)
                return 0;
        }
      
    -+  if (!strcmp("http.resolve", var)) {
    ++  if (!strcmp("http.curloptresolve", var)) {
     +          if (!value) {
     +                  return config_error_nonbool(var);
     +          } else if (!*value) {
    @@ t/t5551-http-fetch-smart.sh: test_expect_success 'client falls back from v2 to v
     +  BOGUS_HOST=gitbogusexamplehost.com &&
     +  BOGUS_HTTPD_URL=$HTTPD_PROTO://$BOGUS_HOST:$LIB_HTTPD_PORT &&
     +  test_must_fail git ls-remote "$BOGUS_HTTPD_URL/smart/repo.git" >/dev/null &&
    -+  git -c "http.resolve=$BOGUS_HOST:$LIB_HTTPD_PORT:127.0.0.1" ls-remote "$BOGUS_HTTPD_URL/smart/repo.git" >/dev/null
    ++  git -c "http.curloptResolve=$BOGUS_HOST:$LIB_HTTPD_PORT:127.0.0.1" ls-remote "$BOGUS_HTTPD_URL/smart/repo.git" >/dev/null
     +'
     +
      test_done
 Documentation/config/http.txt | 16 ++++++++++++++++
 http.c                        | 18 ++++++++++++++++++
 t/t5551-http-fetch-smart.sh   |  7 +++++++
 3 files changed, 41 insertions(+)
diff --git a/Documentation/config/http.txt b/Documentation/config/http.txt
index 7003661c0d..179d03e57b 100644
--- a/Documentation/config/http.txt
+++ b/Documentation/config/http.txt
@@ -98,6 +98,22 @@ http.version::
 	- HTTP/2
 	- HTTP/1.1
 
+http.curloptResolve::
+	Hostname resolution information that will be used first by
+	libcurl when sending HTTP requests.  This information should
+	be in one of the following formats:
+
+	- [+]HOST:PORT:ADDRESS[,ADDRESS]
+	- -HOST:PORT
+
++
+The first format redirects all requests to the given `HOST:PORT`
+to the provided `ADDRESS`(s). The second format clears all
+previous config values for that `HOST:PORT` combination.  To
+allow easy overriding of all the settings inherited from the
+system config, an empty value will reset all resolution
+information to the empty list.
+
 http.sslVersion::
 	The SSL version to use when negotiating an SSL connection, if you
 	want to force the default.  The available and default version
diff --git a/http.c b/http.c
index 229da4d148..8beacb95cc 100644
--- a/http.c
+++ b/http.c
@@ -128,6 +128,8 @@ static struct curl_slist *pragma_header;
 static struct curl_slist *no_pragma_header;
 static struct string_list extra_http_headers = STRING_LIST_INIT_DUP;
 
+static struct curl_slist *host_resolutions;
+
 static struct active_request_slot *active_queue_head;
 
 static char *cached_accept_language;
@@ -393,6 +395,18 @@ static int http_options(const char *var, const char *value, void *cb)
 		return 0;
 	}
 
+	if (!strcmp("http.curloptresolve", var)) {
+		if (!value) {
+			return config_error_nonbool(var);
+		} else if (!*value) {
+			curl_slist_free_all(host_resolutions);
+			host_resolutions = NULL;
+		} else {
+			host_resolutions = curl_slist_append(host_resolutions, value);
+		}
+		return 0;
+	}
+
 	if (!strcmp("http.followredirects", var)) {
 		if (value && !strcmp(value, "initial"))
 			http_follow_config = HTTP_FOLLOW_INITIAL;
@@ -1131,6 +1145,9 @@ void http_cleanup(void)
 	curl_slist_free_all(no_pragma_header);
 	no_pragma_header = NULL;
 
+	curl_slist_free_all(host_resolutions);
+	host_resolutions = NULL;
+
 	if (curl_http_proxy) {
 		free((void *)curl_http_proxy);
 		curl_http_proxy = NULL;
@@ -1211,6 +1228,7 @@ struct active_request_slot *get_active_slot(void)
 	if (curl_save_cookies)
 		curl_easy_setopt(slot->curl, CURLOPT_COOKIEJAR, curl_cookie_file);
 	curl_easy_setopt(slot->curl, CURLOPT_HTTPHEADER, pragma_header);
+	curl_easy_setopt(slot->curl, CURLOPT_RESOLVE, host_resolutions);
 	curl_easy_setopt(slot->curl, CURLOPT_ERRORBUFFER, curl_errorstr);
 	curl_easy_setopt(slot->curl, CURLOPT_CUSTOMREQUEST, NULL);
 	curl_easy_setopt(slot->curl, CURLOPT_READFUNCTION, NULL);
diff --git a/t/t5551-http-fetch-smart.sh b/t/t5551-http-fetch-smart.sh
index f92c79c132..4a8dbb7eee 100755
--- a/t/t5551-http-fetch-smart.sh
+++ b/t/t5551-http-fetch-smart.sh
@@ -567,4 +567,11 @@ test_expect_success 'client falls back from v2 to v0 to match server' '
 	grep symref=HEAD:refs/heads/ trace
 '
 
+test_expect_success 'passing hostname resolution information works' '
+	BOGUS_HOST=gitbogusexamplehost.com &&
+	BOGUS_HTTPD_URL=$HTTPD_PROTO://$BOGUS_HOST:$LIB_HTTPD_PORT &&
+	test_must_fail git ls-remote "$BOGUS_HTTPD_URL/smart/repo.git" >/dev/null &&
+	git -c "http.curloptResolve=$BOGUS_HOST:$LIB_HTTPD_PORT:127.0.0.1" ls-remote "$BOGUS_HTTPD_URL/smart/repo.git" >/dev/null
+'
+
 test_done

-- 
2.36.1.20.g51170867bd
Previous: Christian CouderNext: Carlo Arenas
Message 13 of 20 in “http: add custom hostname to IP address resolves”
  1. http: add custom hostname to IP address resolvesChristian Couder, May 2, 2022
  2. Junio C HamanoMay 2, 2022
  3. Christian CouderMay 4, 2022
  4. Junio C HamanoMay 4, 2022
  5. Christian CouderMay 5, 2022
  6. Carlo Marcelo Arenas BelónMay 5, 2022
  7. Christian CouderMay 9, 2022
  8. http: add custom hostname to IP address resolutionsChristian Couder, May 4, 2022
  9. Carlo Marcelo Arenas BelónMay 5, 2022
  10. Christian CouderMay 12, 2022
  11. Junio C HamanoMay 12, 2022
  12. Christian CouderMay 12, 2022
  13. http: add custom hostname to IP address resolutionsChristian Couder, May 9, 2022
  14. Carlo ArenasMay 10, 2022
  15. Christian CouderMay 12, 2022
  16. Carlo ArenasMay 12, 2022
  17. Patrick SteinhardtMay 12, 2022
  18. Carlo ArenasMay 12, 2022
  19. Junio C HamanoMay 12, 2022
  20. http: add custom hostname to IP address resolutionsChristian Couder, May 16, 2022

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