Subject: [PATCH v2] remote-curl: send Accept-Language header to server

From: "Li Linchao via GitGitGadget" <[email-masked]>
Date: Thu, 09 Jun 2022 06:35:23 +0000

From: Li Linchao <[email-masked]>

Git server end's ability to accept Accept-Language header was introduced
in f18604bbf2(http: add Accept-Language header if possible), but this is
only used by very early phase of the transfer, that's HTTP GET request to
discover references. For other phases, like POST request in the smart HTTP
the server side don't know what language the client speaks.

Teach git client to learn end-user's preferred language and throw
accept-language header to the server side. Once the server gets this header,
it has the ability to talk to end-user with language they understand.
This would be very helpful for many non-English speakers.

Signed-off-by: Li Linchao <[email-masked]>
---
    remote-curl: send Accept-Language header to server
    
    Changes since v1:
    
     * change get_accept_language() to http_get_accept_language_header()
     * reuse test case in t5550
     * reword commit message
    
    TODO: For SSH tranport, give it an environment variable to understand
    locale language.

Published-As: https://github.com/gitgitgadget/git/releases/tag/pr-1251%2FCactusinhand%2Fllc%2Fsend-Accept-Language-header-to-HTTP-server-v2
Fetch-It-Via: git fetch https://github.com/gitgitgadget/git pr-1251/Cactusinhand/llc/send-Accept-Language-header-to-HTTP-server-v2
Pull-Request: https://github.com/gitgitgadget/git/pull/1251

Range-diff vs v1:

 1:  b09f10b6c06 ! 1:  a2dd9d4070e remote-curl: send Accept-Language header to server
     @@
       ## Metadata ##
     -Author: Cactusinhand <[email-masked]>
     +Author: Li Linchao <[email-masked]>
      
       ## Commit message ##
          remote-curl: send Accept-Language header to server
     @@ Commit message
          in f18604bbf2(http: add Accept-Language header if possible), but this is
          only used by very early phase of the transfer, that's HTTP GET request to
          discover references. For other phases, like POST request in the smart HTTP
     -    the server side don't know what language client speak.
     +    the server side don't know what language the client speaks.
      
     -    This patch teaches git client to learn end-user's preferred language and
     -    throw accept-language header to server side. Once server get this header
     -    it have ability to talk to end-user with language they understand, this
     -    would be very helpful for many non-English speakers.
     +    Teach git client to learn end-user's preferred language and throw
     +    accept-language header to the server side. Once the server gets this header,
     +    it has the ability to talk to end-user with language they understand.
     +    This would be very helpful for many non-English speakers.
      
          Signed-off-by: Li Linchao <[email-masked]>
      
     @@ http.c: static void write_accept_language(struct strbuf *buf)
        *   LANGUAGE= LANG=C -> ""
        */
      -static const char *get_accept_language(void)
     -+const char *get_accept_language(void)
     ++const char *http_get_accept_language_header(void)
       {
       	if (!cached_accept_language) {
       		struct strbuf buf = STRBUF_INIT;
     +@@ http.c: static int http_request(const char *url,
     + 					 fwrite_buffer);
     + 	}
     + 
     +-	accept_language = get_accept_language();
     ++	accept_language = http_get_accept_language_header();
     + 
     + 	if (accept_language)
     + 		headers = curl_slist_append(headers, accept_language);
      
       ## http.h ##
      @@ http.h: int http_fetch_ref(const char *base, struct ref *ref);
     @@ http.h: int http_fetch_ref(const char *base, struct ref *ref);
       			struct packed_git **packs_head);
       
      +/* Helper for getting Accept-Language header */
     -+const char *get_accept_language(void);
     ++const char *http_get_accept_language_header(void);
      +
       struct http_pack_request {
       	char *url;
     @@ remote-curl.c: static int rpc_service(struct rpc_state *rpc, struct discovery *h
       	strbuf_addf(&buf, "%s%s", url.buf, svc);
       	rpc->service_url = strbuf_detach(&buf, NULL);
       
     -+	accept_language = get_accept_language();
     ++	accept_language = http_get_accept_language_header();
      +	if (accept_language) {
      +		strbuf_addstr(&buf, accept_language);
      +		rpc->hdr_accept_language = strbuf_detach(&buf, NULL);
     @@ remote-curl.c: static int stateless_connect(const char *service_name)
       	struct discovery *discover;
       	struct rpc_state rpc;
       	struct strbuf buf = STRBUF_INIT;
     --
      +	const char *accept_language;
     + 
       	/*
       	 * Run the info/refs request and see if the server supports protocol
     - 	 * v2.  If and only if the server supports v2 can we successfully
      @@ remote-curl.c: static int stateless_connect(const char *service_name)
       		printf("\n");
       		fflush(stdout);
       	}
     -+	accept_language = get_accept_language();
     -+	if (accept_language) {
     ++	accept_language = http_get_accept_language_header();
     ++	if (accept_language)
      +		rpc.hdr_accept_language = xstrfmt("%s", accept_language);
     -+	}
       
       	rpc.service_name = service_name;
       	rpc.service_url = xstrfmt("%s%s", url.buf, rpc.service_name);
     @@ t/t5541-http-push-smart.sh: test_expect_success 'push to remote repository (stan
       '
      
       ## t/t5550-http-fetch-dumb.sh ##
     -@@ t/t5550-http-fetch-dumb.sh: ja;q=0.95, zh;q=0.94, sv;q=0.93, pt;q=0.92, nb;q=0.91, *;q=0.90" \
     +@@ t/t5550-http-fetch-dumb.sh: test_expect_success 'git client sends Accept-Language correctly with unordinary
     + 	check_language "ko-KR, en-US;q=0.9, *;q=0.8" "ko_KR::en_US" &&
     + 	check_language "ko-KR, *;q=0.9" ":::ko_KR" &&
     + 	check_language "ko-KR, en-US;q=0.9, *;q=0.8" "ko_KR!!:en_US" &&
     +-	check_language "ko-KR, ja-JP;q=0.9, *;q=0.8" "ko_KR en_US:ja_JP"'
     ++	check_language "ko-KR, ja-JP;q=0.9, zh-CN;q=0.8, *;q=0.7" "ko_KR en_US:ja_JP:zh_CN"'
     + 
     + test_expect_success 'git client sends Accept-Language with many preferred languages' '
     +-	check_language "ko-KR, en-US;q=0.9, fr-CA;q=0.8, de;q=0.7, sr;q=0.6, \
     +-ja;q=0.5, zh;q=0.4, sv;q=0.3, pt;q=0.2, *;q=0.1" \
     +-		ko_KR.EUC-KR:en_US.UTF-8:fr_CA:de.UTF-8@euro:sr@latin:ja:zh:sv:pt &&
     ++	check_language "ko-KR, en-US;q=0.99, fr-CA;q=0.98, de;q=0.97, sr;q=0.96, \
     ++ja;q=0.95, zh;q=0.94, sv;q=0.93, pt;q=0.92, zh-CN;q=0.91, *;q=0.90" \
     ++		ko_KR.EUC-KR:en_US.UTF-8:fr_CA:de.UTF-8@euro:sr@latin:ja:zh:sv:pt:zh_CN &&
     + 	check_language "ko-KR, en-US;q=0.99, fr-CA;q=0.98, de;q=0.97, sr;q=0.96, \
     + ja;q=0.95, zh;q=0.94, sv;q=0.93, pt;q=0.92, nb;q=0.91, *;q=0.90" \
       		ko_KR.EUC-KR:en_US.UTF-8:fr_CA:de.UTF-8@euro:sr@latin:ja:zh:sv:pt:nb
       '

 http.c                      |  4 ++--
 http.h                      |  3 +++
 remote-curl.c               | 16 ++++++++++++++++
 t/t5541-http-push-smart.sh  | 19 +++++++++++++++++++
 t/t5550-http-fetch-dumb.sh  | 10 +++++-----
 t/t5551-http-fetch-smart.sh | 10 ++++++++--
 6 files changed, 53 insertions(+), 9 deletions(-)

diff --git a/http.c b/http.c
index 11c6f69facd..33301d8d5d5 100644
--- a/http.c
+++ b/http.c
@@ -1775,7 +1775,7 @@ static void write_accept_language(struct strbuf *buf)
  *   LANGUAGE= LANG=en_US.UTF-8 -> "Accept-Language: en-US, *; q=0.1"
  *   LANGUAGE= LANG=C -> ""
  */
-static const char *get_accept_language(void)
+const char *http_get_accept_language_header(void)
 {
 	if (!cached_accept_language) {
 		struct strbuf buf = STRBUF_INIT;
@@ -1829,7 +1829,7 @@ static int http_request(const char *url,
 					 fwrite_buffer);
 	}
 
-	accept_language = get_accept_language();
+	accept_language = http_get_accept_language_header();
 
 	if (accept_language)
 		headers = curl_slist_append(headers, accept_language);
diff --git a/http.h b/http.h
index ba303cfb372..3c94c479100 100644
--- a/http.h
+++ b/http.h
@@ -178,6 +178,9 @@ int http_fetch_ref(const char *base, struct ref *ref);
 int http_get_info_packs(const char *base_url,
 			struct packed_git **packs_head);
 
+/* Helper for getting Accept-Language header */
+const char *http_get_accept_language_header(void);
+
 struct http_pack_request {
 	char *url;
 
diff --git a/remote-curl.c b/remote-curl.c
index 67f178b1120..504bbdedbda 100644
--- a/remote-curl.c
+++ b/remote-curl.c
@@ -580,6 +580,7 @@ struct rpc_state {
 	char *service_url;
 	char *hdr_content_type;
 	char *hdr_accept;
+	char *hdr_accept_language;
 	char *protocol_header;
 	char *buf;
 	size_t alloc;
@@ -932,6 +933,10 @@ static int post_rpc(struct rpc_state *rpc, int stateless_connect, int flush_rece
 	headers = curl_slist_append(headers, needs_100_continue ?
 		"Expect: 100-continue" : "Expect:");
 
+	/* Add Accept-Language header */
+	if (rpc->hdr_accept_language)
+		headers = curl_slist_append(headers, rpc->hdr_accept_language);
+
 	/* Add the extra Git-Protocol header */
 	if (rpc->protocol_header)
 		headers = curl_slist_append(headers, rpc->protocol_header);
@@ -1058,6 +1063,7 @@ static int rpc_service(struct rpc_state *rpc, struct discovery *heads,
 		       struct strbuf *rpc_result)
 {
 	const char *svc = rpc->service_name;
+	const char *accept_language;
 	struct strbuf buf = STRBUF_INIT;
 	struct child_process client = CHILD_PROCESS_INIT;
 	int err = 0;
@@ -1080,6 +1086,12 @@ static int rpc_service(struct rpc_state *rpc, struct discovery *heads,
 	strbuf_addf(&buf, "%s%s", url.buf, svc);
 	rpc->service_url = strbuf_detach(&buf, NULL);
 
+	accept_language = http_get_accept_language_header();
+	if (accept_language) {
+		strbuf_addstr(&buf, accept_language);
+		rpc->hdr_accept_language = strbuf_detach(&buf, NULL);
+	}
+
 	strbuf_addf(&buf, "Content-Type: application/x-%s-request", svc);
 	rpc->hdr_content_type = strbuf_detach(&buf, NULL);
 
@@ -1400,6 +1412,7 @@ static int stateless_connect(const char *service_name)
 	struct discovery *discover;
 	struct rpc_state rpc;
 	struct strbuf buf = STRBUF_INIT;
+	const char *accept_language;
 
 	/*
 	 * Run the info/refs request and see if the server supports protocol
@@ -1418,6 +1431,9 @@ static int stateless_connect(const char *service_name)
 		printf("\n");
 		fflush(stdout);
 	}
+	accept_language = http_get_accept_language_header();
+	if (accept_language)
+		rpc.hdr_accept_language = xstrfmt("%s", accept_language);
 
 	rpc.service_name = service_name;
 	rpc.service_url = xstrfmt("%s%s", url.buf, rpc.service_name);
diff --git a/t/t5541-http-push-smart.sh b/t/t5541-http-push-smart.sh
index 2f09ff4fac6..4288a279e9e 100755
--- a/t/t5541-http-push-smart.sh
+++ b/t/t5541-http-push-smart.sh
@@ -80,6 +80,25 @@ test_expect_success 'push to remote repository (standard)' '
 	 test $HEAD = $(git rev-parse --verify HEAD))
 '
 
+test_expect_success 'push to remote repository (standard) with sending Accept-Language' '
+	cat >exp <<-\EOF &&
+	=> Send header: Accept-Language: zh-CN, en;q=0.9, *;q=0.8
+	=> Send header: Accept-Language: zh-CN, en;q=0.9, *;q=0.8
+	EOF
+
+	cd "$ROOT_PATH"/test_repo_clone &&
+	: >path_lang &&
+	git add path_lang &&
+	test_tick &&
+	git commit -m path_lang &&
+	HEAD=$(git rev-parse --verify HEAD) &&
+	GIT_TRACE_CURL=true LANGUAGE="zh_CN:en" git push -v -v 2>err &&
+	! grep "Expect: 100-continue" err &&
+
+	grep "=> Send header: Accept-Language:" err >err.language &&
+	test_cmp exp err.language
+'
+
 test_expect_success 'push already up-to-date' '
 	git push
 '
diff --git a/t/t5550-http-fetch-dumb.sh b/t/t5550-http-fetch-dumb.sh
index f0d9cd584d3..42dd9fe2af7 100755
--- a/t/t5550-http-fetch-dumb.sh
+++ b/t/t5550-http-fetch-dumb.sh
@@ -358,18 +358,18 @@ test_expect_success 'git client sends Accept-Language correctly with unordinary
 	check_language "ko-KR, en-US;q=0.9, *;q=0.8" "ko_KR::en_US" &&
 	check_language "ko-KR, *;q=0.9" ":::ko_KR" &&
 	check_language "ko-KR, en-US;q=0.9, *;q=0.8" "ko_KR!!:en_US" &&
-	check_language "ko-KR, ja-JP;q=0.9, *;q=0.8" "ko_KR en_US:ja_JP"'
+	check_language "ko-KR, ja-JP;q=0.9, zh-CN;q=0.8, *;q=0.7" "ko_KR en_US:ja_JP:zh_CN"'
 
 test_expect_success 'git client sends Accept-Language with many preferred languages' '
-	check_language "ko-KR, en-US;q=0.9, fr-CA;q=0.8, de;q=0.7, sr;q=0.6, \
-ja;q=0.5, zh;q=0.4, sv;q=0.3, pt;q=0.2, *;q=0.1" \
-		ko_KR.EUC-KR:en_US.UTF-8:fr_CA:de.UTF-8@euro:sr@latin:ja:zh:sv:pt &&
+	check_language "ko-KR, en-US;q=0.99, fr-CA;q=0.98, de;q=0.97, sr;q=0.96, \
+ja;q=0.95, zh;q=0.94, sv;q=0.93, pt;q=0.92, zh-CN;q=0.91, *;q=0.90" \
+		ko_KR.EUC-KR:en_US.UTF-8:fr_CA:de.UTF-8@euro:sr@latin:ja:zh:sv:pt:zh_CN &&
 	check_language "ko-KR, en-US;q=0.99, fr-CA;q=0.98, de;q=0.97, sr;q=0.96, \
 ja;q=0.95, zh;q=0.94, sv;q=0.93, pt;q=0.92, nb;q=0.91, *;q=0.90" \
 		ko_KR.EUC-KR:en_US.UTF-8:fr_CA:de.UTF-8@euro:sr@latin:ja:zh:sv:pt:nb
 '
 
-test_expect_success 'git client does not send an empty Accept-Language' '
+test_expect_success 'git client send an empty Accept-Language' '
 	GIT_TRACE_CURL=true LANGUAGE= git ls-remote "$HTTPD_URL/dumb/repo.git" 2>stderr &&
 	! grep "^=> Send header: Accept-Language:" stderr
 '
diff --git a/t/t5551-http-fetch-smart.sh b/t/t5551-http-fetch-smart.sh
index b9351a732f6..6f65131a4e4 100755
--- a/t/t5551-http-fetch-smart.sh
+++ b/t/t5551-http-fetch-smart.sh
@@ -31,6 +31,7 @@ test_expect_success 'clone http repository' '
 	> GET /smart/repo.git/info/refs?service=git-upload-pack HTTP/1.1
 	> Accept: */*
 	> Accept-Encoding: ENCODINGS
+	> Accept-Language: zh-CN, en;q=0.9, *;q=0.8
 	> Pragma: no-cache
 	< HTTP/1.1 200 OK
 	< Pragma: no-cache
@@ -40,13 +41,15 @@ test_expect_success 'clone http repository' '
 	> Accept-Encoding: ENCODINGS
 	> Content-Type: application/x-git-upload-pack-request
 	> Accept: application/x-git-upload-pack-result
+	> Accept-Language: zh-CN, en;q=0.9, *;q=0.8
 	> Content-Length: xxx
 	< HTTP/1.1 200 OK
 	< Pragma: no-cache
 	< Cache-Control: no-cache, max-age=0, must-revalidate
 	< Content-Type: application/x-git-upload-pack-result
 	EOF
-	GIT_TRACE_CURL=true GIT_TEST_PROTOCOL_VERSION=0 \
+
+	GIT_TRACE_CURL=true GIT_TEST_PROTOCOL_VERSION=0 LANGUAGE="zh_CN:en" \
 		git clone --quiet $HTTPD_URL/smart/repo.git clone 2>err &&
 	test_cmp file clone/file &&
 	tr '\''\015'\'' Q <err |
@@ -94,7 +97,10 @@ test_expect_success 'clone http repository' '
 		test_cmp exp actual.smudged &&
 
 		grep "Accept-Encoding:.*gzip" actual >actual.gzip &&
-		test_line_count = 2 actual.gzip
+		test_line_count = 2 actual.gzip &&
+
+		grep "Accept-Language: zh-CN, en" actual >actual.language &&
+		test_line_count = 2 actual.language
 	fi
 '

base-commit: ab336e8f1c8009c8b1aab8deb592148e69217085
-- 
gitgitgadget