[Net] Fix HTTPRequest gzip with high compression ratio.

Decompress each body chunk over multiple iterations, this causes more
reallocations, but it ensures decompression will not fail no matter the
compression ratio.

1 files changed, 34 insertions, 15 deletions

diff --git a/scene/main/http_request.cpp b/scene/main/http_request.cpp
index 2c395ec07d..62f362553f 100644
--- a/scene/main/http_request.cpp
+++ b/scene/main/http_request.cpp
@@ -276,10 +276,10 @@ bool HTTPRequest::_handle_response(bool *ret_value) {
 	}
 	if (content_encoding == "gzip") {
 		decompressor.instantiate();
-		decompressor->start_decompression(false, get_download_chunk_size() * 2);
+		decompressor->start_decompression(false, get_download_chunk_size());
 	} else if (content_encoding == "deflate") {
 		decompressor.instantiate();
-		decompressor->start_decompression(true, get_download_chunk_size() * 2);
+		decompressor->start_decompression(true, get_download_chunk_size());
 	}
 
 	return false;
@@ -390,19 +390,38 @@ bool HTTPRequest::_update_connection() {
 				return false;
 			}
 
-			PackedByteArray chunk = client->read_response_body_chunk();
-			downloaded.add(chunk.size());
-
-			// Decompress chunk if needed.
-			if (decompressor.is_valid()) {
-				Error err = decompressor->put_data(chunk.ptr(), chunk.size());
-				if (err == OK) {
-					chunk.resize(decompressor->get_available_bytes());
-					err = decompressor->get_data(chunk.ptrw(), chunk.size());
-				}
-				if (err != OK) {
-					_defer_done(RESULT_BODY_DECOMPRESS_FAILED, response_code, response_headers, PackedByteArray());
-					return true;
+			PackedByteArray chunk;
+			if (decompressor.is_null()) {
+				// Chunk can be read directly.
+				chunk = client->read_response_body_chunk();
+				downloaded.add(chunk.size());
+			} else {
+				// Chunk is the result of decompression.
+				PackedByteArray compressed = client->read_response_body_chunk();
+				downloaded.add(compressed.size());
+
+				int pos = 0;
+				int left = compressed.size();
+				while (left) {
+					int w = 0;
+					Error err = decompressor->put_partial_data(compressed.ptr() + pos, left, w);
+					if (err == OK) {
+						PackedByteArray dc;
+						dc.resize(decompressor->get_available_bytes());
+						err = decompressor->get_data(dc.ptrw(), dc.size());
+						chunk.append_array(dc);
+					}
+					if (err != OK) {
+						_defer_done(RESULT_BODY_DECOMPRESS_FAILED, response_code, response_headers, PackedByteArray());
+						return true;
+					}
+					// We need this check here because a "zip bomb" could result in a chunk of few kilos decompressing into gigabytes of data.
+					if (body_size_limit >= 0 && final_body_size.get() + chunk.size() > body_size_limit) {
+						_defer_done(RESULT_BODY_SIZE_LIMIT_EXCEEDED, response_code, response_headers, PackedByteArray());
+						return true;
+					}
+					pos += w;
+					left -= w;
 				}
 			}
 			final_body_size.add(chunk.size());