Add MultipartParser fuzz target

fuzzing/Makefile

@@ -22,6 +22,7 @@ oss-fuzz:
 # "Unit tests"
 	$(CXX) $(CXXFLAGS) -std=c++17 -O3 Extensions.cpp -o $(OUT)/Extensions $(LIB_FUZZING_ENGINE)
 	$(CXX) $(CXXFLAGS) -std=c++17 -O3 QueryParser.cpp -o $(OUT)/QueryParser $(LIB_FUZZING_ENGINE)
+	$(CXX) $(CXXFLAGS) -std=c++17 -O3 MultipartParser.cpp -o $(OUT)/MultipartParser $(LIB_FUZZING_ENGINE)
 	$(CXX) $(CXXFLAGS) -std=c++17 -O3 WebSocket.cpp -o $(OUT)/WebSocket $(LIB_FUZZING_ENGINE)
 	$(CXX) $(CXXFLAGS) -std=c++17 -O3 Http.cpp -o $(OUT)/Http $(LIB_FUZZING_ENGINE)
 	$(CXX) $(CXXFLAGS) -DUWS_WITH_PROXY -std=c++17 -O3 Http.cpp -o $(OUT)/HttpWithProxy $(LIB_FUZZING_ENGINE)

fuzzing/MultipartParser.cpp

@@ -0,0 +1,62 @@
+/* This is a fuzz test of the multipart parser */
+
+#define WIN32_EXPORT
+
+#include <cstdio>
+#include <string>
+#include <cstdlib>
+
+#include "../src/Multipart.h"
+
+extern "C" int LLVMFuzzerTestOneInput(const uint8_t *data, size_t size) {
+
+    if (!size) {
+        return 0;
+    }
+
+    char *mutableMemory = (char *) malloc(size);
+    memcpy(mutableMemory, data, size);
+
+    /* First byte determines how long contentType is */
+    unsigned char contentTypeLength = data[0];
+    size--;
+
+    std::string_view contentType((char *) mutableMemory + 1, std::min<size_t>(contentTypeLength, size));
+    size -= contentType.length();
+
+    std::string_view body((char *) mutableMemory + 1 + contentType.length(), size);
+
+    uWS::MultipartParser mp(contentType);
+    if (mp.isValid()) {
+        mp.setBody(body);
+
+        std::pair<std::string_view, std::string_view> headers[10];
+
+        while (true) {
+            std::optional<std::string_view> optionalPart = mp.getNextPart(headers);
+            if (!optionalPart.has_value()) {
+                break;
+            }
+
+            std::string_view part = optionalPart.value();
+
+            for (int i = 0; headers[i].first.length(); i++) {
+                /* We care about content-type and content-disposition */
+                if (headers[i].first == "content-disposition") {
+                    /* Parse the parameters */
+                    uWS::ParameterParser pp(headers[i].second);
+                    while (true) {
+                        auto [key, value] = pp.getKeyValue();
+                        if (!key.length()) {
+                            break;
+                        }
+                    }
+                }
+            }
+        }
+    }
+
+    free(mutableMemory);
+    return 0;
+}
+