feat: sentry add gzipped with compression

CHANGELOG.md

@@ -2,9 +2,10 @@
 
 ## Unreleased
 
-**Features**
+**Features**:
 
- Add user feedback capability to the Native SDK ([#966](https://github.com/getsentry/sentry-native/pull/966))
+- Add optional Gzip transport compression via build option `SENTRY_TRANSPORT_COMPRESSION`. Requires system `zlib`. ([#954](https://github.com/getsentry/sentry-native/pull/954))
+- Add user feedback capability to the Native SDK ([#966](https://github.com/getsentry/sentry-native/pull/966))
 
 **Internal**:
 
@@ -14,6 +15,10 @@
 
 - Add usage of the breadcrumb `data` property to the example. [#951](https://github.com/getsentry/sentry-native/pull/951)
 
+**Thank you**:
+
+- [@Strive-Sun](https://github.com/Strive-Sun)
+
 ## 0.7.0
 
 **Breaking changes**:
@@ -39,6 +44,7 @@ Features, fixes and improvements in this release have been contributed by:
 
 - [@compnerd](https://github.com/compnerd)
 - [@stima](https://github.com/stima)
+- [@hyp](https://github.com/hyp)
 
 ## 0.6.7
 

CMakeLists.txt

@@ -55,6 +55,8 @@ endif()
 
 option(SENTRY_PIC "Build sentry (and dependent) libraries as position independent libraries" ON)
 
+option(SENTRY_TRANSPORT_COMPRESSION "Enable transport gzip compression" OFF)
+
 option(SENTRY_BUILD_TESTS "Build sentry-native tests" "${SENTRY_MAIN_PROJECT}")
 option(SENTRY_BUILD_EXAMPLES "Build sentry-native example(s)" "${SENTRY_MAIN_PROJECT}")
 
@@ -278,17 +280,20 @@ if(SENTRY_TRANSPORT_CURL)
 		find_package(CURL REQUIRED COMPONENTS AsynchDNS)
 	endif()
 
-	if(TARGET CURL::libcurl) # Only available in cmake 3.12+
-		target_link_libraries(sentry PRIVATE CURL::libcurl)
-	else()
-		# Needed for cmake < 3.12 support (cmake 3.12 introduced the target CURL::libcurl)
-		target_include_directories(sentry PRIVATE ${CURL_INCLUDE_DIR})
-		# The exported sentry target must not contain any path of the build machine, therefore use generator expressions
-		string(REPLACE ";" "$<SEMICOLON>" GENEX_CURL_LIBRARIES "${CURL_LIBRARIES}")
-		string(REPLACE ";" "$<SEMICOLON>" GENEX_CURL_COMPILE_DEFINITIONS "${CURL_COMPILE_DEFINITIONS}")
-		target_link_libraries(sentry PRIVATE $<BUILD_INTERFACE:${GENEX_CURL_LIBRARIES}>)
-		target_compile_definitions(sentry PRIVATE $<BUILD_INTERFACE:${GENEX_CURL_COMPILE_DEFINITIONS}>)
+	target_link_libraries(sentry PRIVATE CURL::libcurl)
+endif()
+
+if(SENTRY_TRANSPORT_COMPRESSION)
+	if(NOT ZLIB_FOUND)
+		find_package(ZLIB REQUIRED)
 	endif()
+
+	if(SENTRY_BACKEND_CRASHPAD)
+		set(CRASHPAD_ZLIB_SYSTEM ON CACHE BOOL "Force CRASHPAD_ZLIB_SYSTEM when enabling transport compression" FORCE)
+	endif()
+
+	target_link_libraries(sentry PRIVATE ZLIB::ZLIB)
+	target_compile_definitions(sentry PRIVATE SENTRY_TRANSPORT_COMPRESSION)
 endif()
 
 set_property(TARGET sentry PROPERTY C_VISIBILITY_PRESET hidden)
@@ -413,9 +418,6 @@ if(SENTRY_WITH_LIBUNWINDSTACK)
 endif()
 
 if(SENTRY_BACKEND_CRASHPAD)
-	# FIXME: required for cmake 3.12 and lower:
-	# - NEW behavior lets normal variable override option
-	cmake_policy(SET CMP0077 NEW)
 	if(SENTRY_BUILD_SHARED_LIBS)
 		set(CRASHPAD_ENABLE_INSTALL OFF CACHE BOOL "Enable crashpad installation" FORCE)
 	else()
@@ -593,4 +595,4 @@ endif()
 if(SENTRY_BUILD_SHARED_LIBS)
 	target_link_libraries(sentry PRIVATE
 			"$<$<OR:$<PLATFORM_ID:Linux>,$<PLATFORM_ID:Android>>:-Wl,--build-id=sha1,--version-script=${PROJECT_SOURCE_DIR}/src/exports.map>")
-endif()
+endif()

src/sentry_transport.c

@@ -5,9 +5,19 @@
 #include "sentry_ratelimiter.h"
 #include "sentry_string.h"
 
+#ifdef SENTRY_TRANSPORT_COMPRESSION
+#    include "zlib.h"
+#endif
+
 #define ENVELOPE_MIME "application/x-sentry-envelope"
+#ifdef SENTRY_TRANSPORT_COMPRESSION
+// The headers we use are: `x-sentry-auth`, `content-type`, `content-encoding`,
+// `content-length`
+#    define MAX_HTTP_HEADERS 4
+#else
 // The headers we use are: `x-sentry-auth`, `content-type`, `content-length`
-#define MAX_HTTP_HEADERS 3
+#    define MAX_HTTP_HEADERS 3
+#endif
 
 typedef struct sentry_transport_s {
     void (*send_envelope_func)(sentry_envelope_t *envelope, void *state);
@@ -148,6 +158,56 @@ sentry_transport_free(sentry_transport_t *transport)
     sentry_free(transport);
 }
 
+#ifdef SENTRY_TRANSPORT_COMPRESSION
+static bool
+gzipped_with_compression(const char *body, const size_t body_len,
+    char **compressed_body, size_t *compressed_body_len)
+{
+    if (!body || body_len == 0) {
+        return false;
+    }
+
+    z_stream stream;
+    memset(&stream, 0, sizeof(stream));
+    stream.next_in = body;
+    stream.avail_in = body_len;
+
+    int err = deflateInit2(&stream, Z_DEFAULT_COMPRESSION, Z_DEFLATED,
+        MAX_WBITS + 16, 9, Z_DEFAULT_STRATEGY);
+    if (err != Z_OK) {
+        SENTRY_TRACEF("deflateInit2 failed: %d", err);
+        return false;
+    }
+
+    size_t len = compressBound(body_len);
+    char *buffer = sentry_malloc(len);
+    if (!buffer) {
+        deflateEnd(&stream);
+        return false;
+    }
+
+    while (err == Z_OK) {
+        stream.next_out = buffer + stream.total_out;
+        stream.avail_out = len - stream.total_out;
+        err = deflate(&stream, Z_FINISH);
+    }
+
+    if (err != Z_STREAM_END) {
+        SENTRY_TRACEF("deflate failed: %d", err);
+        sentry_free(buffer);
+        buffer = NULL;
+        deflateEnd(&stream);
+        return false;
+    }
+
+    *compressed_body_len = stream.total_out;
+    *compressed_body = buffer;
+
+    deflateEnd(&stream);
+    return true;
+}
+#endif
+
 sentry_prepared_http_request_t *
 sentry__prepare_http_request(sentry_envelope_t *envelope,
     const sentry_dsn_t *dsn, const sentry_rate_limiter_t *rl,
@@ -165,6 +225,23 @@ sentry__prepare_http_request(sentry_envelope_t *envelope,
         return NULL;
     }
 
+    bool compressed = false;
+#ifdef SENTRY_TRANSPORT_COMPRESSION
+    char *compressed_body = NULL;
+    size_t compressed_body_len = 0;
+    compressed = gzipped_with_compression(
+        body, body_len, &compressed_body, &compressed_body_len);
+    if (compressed) {
+        if (body_owned) {
+            sentry_free(body);
+            body_owned = false;
+        }
+        body = compressed_body;
+        body_len = compressed_body_len;
+        body_owned = true;
+    }
+#endif
+
     sentry_prepared_http_request_t *req
         = SENTRY_MAKE(sentry_prepared_http_request_t);
     if (!req) {
@@ -196,6 +273,12 @@ sentry__prepare_http_request(sentry_envelope_t *envelope,
     h->key = "content-type";
     h->value = sentry__string_clone(ENVELOPE_MIME);
 
+    if (compressed) {
+        h = &req->headers[req->headers_len++];
+        h->key = "content-encoding";
+        h->value = sentry__string_clone("gzip");
+    }
+
     h = &req->headers[req->headers_len++];
     h->key = "content-length";
     h->value = sentry__int64_to_string((int64_t)body_len);