Allow a zero byte padding after deflate input

Author: uNetworkingAB

src/PerMessageDeflate.h

@@ -222,7 +222,9 @@ struct InflationStream {
             ((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()) {
+            /* DEFLATE is not a byte aligned format, so we might end up consuming 1 byte less than the input */
+            /* This extra byte is zero-padding. */
+            if (res == 0 && consumed == compressed.length() || (consumed == compressed.length() - 1 && compressed.data()[consumed] == 0)) {
                 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 */