Add libEpollFuzzer and a new fuzz target

.gitmodules

@@ -1,3 +1,6 @@
 [submodule "uSockets"]
 	path = uSockets
 	url = https://github.com/uNetworking/uSockets.git
+[submodule "fuzzing/libEpollFuzzer"]
+	path = fuzzing/libEpollFuzzer
+	url = https://github.com/uNetworking/libEpollFuzzer

fuzzing/EpollHelloWorld.cpp

@@ -0,0 +1,69 @@
+/* We rely on wrapped syscalls */
+#include "libEpollFuzzer/epoll_fuzzer.h"
+
+#include "App.h"
+
+/* We keep this one for teardown later on */
+struct us_listen_socket_t *listen_socket;
+
+/* This test is run by libEpollFuzzer */
+void test() {
+	/* ws->getUserData returns one of these */
+    struct PerSocketData {
+        /* Fill with user data */
+    };
+
+    /* Keep in mind that uWS::SSLApp({options}) is the same as uWS::App() when compiled without SSL support.
+     * You may swap to using uWS:App() if you don't need SSL */
+    uWS::App({
+        /* There are example certificates in uWebSockets.js repo */
+	    .key_file_name = "../misc/key.pem",
+	    .cert_file_name = "../misc/cert.pem",
+	    .passphrase = "1234"
+	}).ws<PerSocketData>("/*", {
+        /* Settings */
+        .compression = uWS::SHARED_COMPRESSOR,
+        .maxPayloadLength = 16 * 1024,
+        .idleTimeout = 10,
+        .maxBackpressure = 1 * 1024 * 1024,
+        /* Handlers */
+        .open = [](auto *ws) {
+            /* Open event here, you may access ws->getUserData() which points to a PerSocketData struct */
+        },
+        .message = [](auto *ws, std::string_view message, uWS::OpCode opCode) {
+            ws->send(message, opCode, true);
+        },
+        .drain = [](auto *ws) {
+            /* Check ws->getBufferedAmount() here */
+        },
+        .ping = [](auto *ws) {
+            /* Not implemented yet */
+        },
+        .pong = [](auto *ws) {
+            /* Not implemented yet */
+        },
+        .close = [](auto *ws, int code, std::string_view message) {
+            /* You may access ws->getUserData() here */
+        }
+    }).listen(9001, [](auto *listenSocket) {
+		listen_socket = listenSocket;
+    }).run();
+
+	uWS::Loop::get()->free();
+}
+
+/* Thus function should shutdown the event-loop and let the test fall through */
+void teardown() {
+	/* If we are called twice there's a bug (it potentially could if
+	 * all open sockets cannot be error-closed in one epoll_wait call).
+	 * But we only allow 1k FDs and we have a buffer of 1024 from epoll_wait */
+	if (!listen_socket) {
+		exit(-1);
+	}
+
+	/* We might have open sockets still, and these will be error-closed by epoll_wait */
+	// us_socket_context_close - close all open sockets created with this socket context
+
+	us_listen_socket_close(0, listen_socket);
+	listen_socket = NULL;
+}

fuzzing/Makefile

@@ -5,7 +5,16 @@ CXXFLAGS ?= -DLIBUS_NO_SSL -fsanitize=$(SANITIZER),fuzzer
 CFLAGS ?= -DLIBUS_NO_SSL
 OUT ?= .
 
+# These are fetched from libEpollFuzzer
+WRAPPED_SYSCALLS = -Wl,--wrap=recv,--wrap=read,--wrap=listen,--wrap=getaddrinfo,--wrap=freeaddrinfo,--wrap=setsockopt,--wrap=fcntl,--wrap=bind,--wrap=socket,--wrap=epoll_wait,--wrap=epoll_create1,--wrap=timerfd_settime,--wrap=close,--wrap=accept4,--wrap=eventfd,--wrap=timerfd_create,--wrap=epoll_ctl,--wrap=shutdown
+
 oss-fuzz:
+# libEpollFuzzer cases
+	# Compile uSockets without -flto
+	rm -rf *.o
+	$(CC) -DLIBUS_NO_SSL -std=c11 -I../uSockets/src -O3 -c ../uSockets/src/*.c ../uSockets/src/eventing/*.c ../uSockets/src/crypto/*.c
+	# Link against object files
+	$(CXX) $(CXXFLAGS) $(WRAPPED_SYSCALLS) -std=c++17 -O2 -DUWS_NO_ZLIB -I../src -I../uSockets/src EpollHelloWorld.cpp -o $(OUT)/EpollHelloWorld $(LIB_FUZZING_ENGINE) *.o
 # "Unit tests"
 	$(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)