[Tarantool-patches] [PATCH v5 2/3] httpc: add curl accept_encoding option

[Ilya Kosarev <i.kosarev@tarantool.org>]

CURLOPT_ACCEPT_ENCODING option is now supported.
This option enables automatic decompression of HTTP downloads.
See https://curl.haxx.se/libcurl/c/CURLOPT_ACCEPT_ENCODING.html

Closes #4232

@TarantoolBot document
Title: httpc: add curl accept_encoding option
Update the documentation for client_object:request() parameters to
reflect new accept_encoding option.
It enables automatic decompression of HTTP downloads by setting the
contents of the Accept-Encoding header sent in a HTTP request and
enabling decoding of a response when a Content-Encoding header is
received.
This is a request, not an order; the server may or may not do it.
Servers might respond with Content-Encoding even without getting
an Accept-Encoding in the request. Servers might respond with a
different Content-Encoding than what was asked for in the request.
@param accept_encoding specifies what encoding you'd like.
This param can be an empty string which means Accept-Encoding header
will contain all built-in supported encodings. This param can be
comma-separated list of accepted encodings, like: "br, gzip, deflate".
Bundled libcurl supports "identity", meaning non-compressed, "deflate"
which requests the server to compress its response using the zlib
algorithm and "gzip" which requests the gzip algorithm. System libcurl
also possibly supports "br" which is brotli.
See https://curl.haxx.se/libcurl/c/CURLOPT_ACCEPT_ENCODING.html
---
 src/httpc.c       | 16 ++++++++++++++++
 src/httpc.h       | 26 ++++++++++++++++++++++++++
 src/lua/httpc.c   |  5 +++++
 src/lua/httpc.lua |  2 ++
 4 files changed, 49 insertions(+)

diff --git a/src/httpc.c b/src/httpc.c
index 212064080..22b54d16a 100644
--- a/src/httpc.c
+++ b/src/httpc.c
@@ -361,6 +361,22 @@ httpc_set_follow_location(struct httpc_request *req, long follow)
 			 follow);
 }
 
+void
+httpc_set_accept_encoding(struct httpc_request *req, const char *encoding)
+{
+/*
+* CURLOPT_ACCEPT_ENCODING was called CURLOPT_ENCODING before
+* libcurl 7.21.6.
+*/
+#if LIBCURL_VERSION_NUM >= 0x071506
+	curl_easy_setopt(req->curl_request.easy, CURLOPT_ACCEPT_ENCODING,
+			 encoding);
+#else
+	curl_easy_setopt(req->curl_request.easy, CURLOPT_ENCODING,
+			 encoding);
+#endif
+}
+
 int
 httpc_execute(struct httpc_request *req, double timeout)
 {
diff --git a/src/httpc.h b/src/httpc.h
index 99fd8fbd4..2fc557107 100644
--- a/src/httpc.h
+++ b/src/httpc.h
@@ -372,6 +372,32 @@ httpc_set_interface(struct httpc_request *req, const char *interface);
 void
 httpc_set_follow_location(struct httpc_request *req, long follow);
 
+/**
+ * Enable automatic decompression of HTTP downloads: set the
+ * contents of the Accept-Encoding header sent in a HTTP request
+ * and enable decoding of a response when a Content-Encoding
+ * header is received.
+ * This is a request, not an order; the server may or may not do
+ * it. Servers might respond with Content-Encoding even without
+ * getting an Accept-Encoding in the request. Servers might
+ * respond with a different Content-Encoding than what was asked
+ * for in the request.
+ * @param req request
+ * @param encoding - specify what encoding you'd like.
+ * This param can be an empty string which means Accept-Encoding
+ * header will contain all built-in supported encodings. This
+ * param can be comma-separated list of accepted encodings, like:
+ * "br, gzip, deflate".
+ * Bundled libcurl supports "identity", meaning non-compressed,
+ * "deflate" which requests the server to compress its response
+ * using the zlib algorithm and "gzip" which requests the gzip
+ * algorithm. System libcurl also possibly supports "br" which
+ * is brotli.
+ * @see https://curl.haxx.se/libcurl/c/CURLOPT_ACCEPT_ENCODING.html
+ */
+void
+httpc_set_accept_encoding(struct httpc_request *req, const char *encoding);
+
 /**
  * This function does async HTTP request
  * @param request - reference to request object with filled fields
diff --git a/src/lua/httpc.c b/src/lua/httpc.c
index a8e3e2525..6ed4eb788 100644
--- a/src/lua/httpc.c
+++ b/src/lua/httpc.c
@@ -315,6 +315,11 @@ luaT_httpc_request(lua_State *L)
 		httpc_set_follow_location(req, lua_toboolean(L, -1));
 	lua_pop(L, 1);
 
+	lua_getfield(L, 5, "accept_encoding");
+	if (!lua_isnil(L, -1))
+		httpc_set_accept_encoding(req, lua_tostring(L, -1));
+	lua_pop(L, 1);
+
 	if (httpc_execute(req, timeout) != 0) {
 		httpc_request_delete(req);
 		return luaT_error(L);
diff --git a/src/lua/httpc.lua b/src/lua/httpc.lua
index ce9bb9771..3224d8c10 100644
--- a/src/lua/httpc.lua
+++ b/src/lua/httpc.lua
@@ -296,6 +296,8 @@ end
 --          'Location' header that a server sends as part of an
 --          3xx response;
 --
+--      accept_encoding - enables automatic decompression of HTTP downloads;
+--
 --  Returns:
 --      {
 --          status=NUMBER,
-- 
2.17.1