Remove libdeflate compression path, fix its decompression path

Author: uNetworkingAB

src/PerMessageDeflate.h

@@ -150,21 +150,6 @@ struct DeflationStream {
     /* Deflate and optionally reset. You must not deflate an empty string. */
     std::string_view deflate(ZlibContext *zlibContext, std::string_view raw, bool reset) {
 
-#ifdef UWS_USE_LIBDEFLATE
-        /* Run a fast path in case of shared_compressor */
-        if (reset) {
-            size_t written = 0;
-            static unsigned char buf[1024 + 1];
-
-            written = libdeflate_deflate_compress(zlibContext->compressor, raw.data(), raw.length(), buf, 1024);
-
-            if (written) {
-                memcpy(&buf[written], "\x00", 1);
-                return std::string_view((char *) buf, written + 1);
-            }
-        }
-#endif
-
         /* Odd place to clear this one, fix */
         zlibContext->dynamicDeflationBuffer.clear();
 
@@ -228,20 +213,19 @@ struct InflationStream {
     std::optional<std::string_view> inflate(ZlibContext *zlibContext, std::string_view compressed, size_t maxPayloadLength, bool reset) {
 
 #ifdef UWS_USE_LIBDEFLATE
-        /* Try fast path first */
-        size_t written = 0;
-        static char buf[1024];
-
-        /* We have to pad 9 bytes and restore those bytes when done since 9 is more than 6 of next WebSocket message */
-        char tmp[9];
-        memcpy(tmp, (char *) compressed.data() + compressed.length(), 9);
-        memcpy((char *) compressed.data() + compressed.length(), "\x00\x00\xff\xff\x01\x00\x00\xff\xff", 9);
-        libdeflate_result res = libdeflate_deflate_decompress(zlibContext->decompressor, compressed.data(), compressed.length() + 9, buf, 1024, &written);
-        memcpy((char *) compressed.data() + compressed.length(), tmp, 9);
-
-        if (res == 0) {
-            /* Fast path wins */
-            return std::string_view(buf, written);
+        /* Try fast path first (assuming single DEFLATE block) */
+        size_t written = 0, consumed;
+        zlibContext->dynamicInflationBuffer.clear();
+        zlibContext->dynamicInflationBuffer.reserve(maxPayloadLength);
+
+        ((char *)compressed.data())[0] |= 0x1; // BFINAL = 1
+        libdeflate_result res = libdeflate_deflate_decompress_ex(zlibContext->decompressor, compressed.data(), compressed.length(), zlibContext->dynamicInflationBuffer.data(), maxPayloadLength, &consumed, &written);
+  
+        if (res == 0 && consumed == compressed.length()) {
+            return std::string_view(zlibContext->dynamicInflationBuffer.data(), written);
+        } else {
+            /* We can only end up here if the first DEFLATE block was not the last, so mark it as such */
+            ((char *)compressed.data())[0] &= ~0x1; // BFINAL = 0
         }
 #endif