netbase: extend CreateSock() to support creating arbitrary sockets

Allow the callers of `CreateSock()` to pass all 3 arguments to the
`socket(2)` syscall. This makes it possible to create sockets of
any domain/type/protocol.

src/net.cpp

@@ -3029,7 +3029,7 @@ bool CConnman::BindListenPort(const CService& addrBind, bilingual_str& strError,
         return false;
     }
 
-    std::unique_ptr<Sock> sock = CreateSock(addrBind.GetSAFamily());
+    std::unique_ptr<Sock> sock = CreateSock(addrBind.GetSAFamily(), SOCK_STREAM, IPPROTO_TCP);
     if (!sock) {
         strError = strprintf(Untranslated("Couldn't open socket for incoming connections (socket returned error %s)"), NetworkErrorString(WSAGetLastError()));
         LogPrintLevel(BCLog::NET, BCLog::Level::Error, "%s\n", strError.original);

src/netbase.cpp

@@ -487,24 +487,23 @@ bool Socks5(const std::string& strDest, uint16_t port, const ProxyCredentials* a
     }
 }
 
-std::unique_ptr<Sock> CreateSockOS(sa_family_t address_family)
+std::unique_ptr<Sock> CreateSockOS(int domain, int type, int protocol)
 {
     // Not IPv4, IPv6 or UNIX
-    if (address_family == AF_UNSPEC) return nullptr;
-
-    int protocol{IPPROTO_TCP};
-#if HAVE_SOCKADDR_UN
-    if (address_family == AF_UNIX) protocol = 0;
-#endif
+    if (domain == AF_UNSPEC) return nullptr;
 
     // Create a socket in the specified address family.
-    SOCKET hSocket = socket(address_family, SOCK_STREAM, protocol);
+    SOCKET hSocket = socket(domain, type, protocol);
     if (hSocket == INVALID_SOCKET) {
         return nullptr;
     }
 
     auto sock = std::make_unique<Sock>(hSocket);
 
+    if (domain != AF_INET && domain != AF_INET6 && domain != AF_UNIX) {
+        return sock;
+    }
+
     // Ensure that waiting for I/O on this socket won't result in undefined
     // behavior.
     if (!sock->IsSelectable()) {
@@ -529,18 +528,21 @@ std::unique_ptr<Sock> CreateSockOS(sa_family_t address_family)
     }
 
 #if HAVE_SOCKADDR_UN
-    if (address_family == AF_UNIX) return sock;
+    if (domain == AF_UNIX) return sock;
 #endif
 
-    // Set the no-delay option (disable Nagle's algorithm) on the TCP socket.
-    const int on{1};
-    if (sock->SetSockOpt(IPPROTO_TCP, TCP_NODELAY, &on, sizeof(on)) == SOCKET_ERROR) {
-        LogPrint(BCLog::NET, "Unable to set TCP_NODELAY on a newly created socket, continuing anyway\n");
+    if (protocol == IPPROTO_TCP) {
+        // Set the no-delay option (disable Nagle's algorithm) on the TCP socket.
+        const int on{1};
+        if (sock->SetSockOpt(IPPROTO_TCP, TCP_NODELAY, &on, sizeof(on)) == SOCKET_ERROR) {
+            LogPrint(BCLog::NET, "Unable to set TCP_NODELAY on a newly created socket, continuing anyway\n");
+        }
     }
+
     return sock;
 }
 
-std::function<std::unique_ptr<Sock>(const sa_family_t&)> CreateSock = CreateSockOS;
+std::function<std::unique_ptr<Sock>(int, int, int)> CreateSock = CreateSockOS;
 
 template<typename... Args>
 static void LogConnectFailure(bool manual_connection, const char* fmt, const Args&... args) {
@@ -609,7 +611,7 @@ static bool ConnectToSocket(const Sock& sock, struct sockaddr* sockaddr, socklen
 
 std::unique_ptr<Sock> ConnectDirectly(const CService& dest, bool manual_connection)
 {
-    auto sock = CreateSock(dest.GetSAFamily());
+    auto sock = CreateSock(dest.GetSAFamily(), SOCK_STREAM, IPPROTO_TCP);
     if (!sock) {
         LogPrintLevel(BCLog::NET, BCLog::Level::Error, "Cannot create a socket for connecting to %s\n", dest.ToStringAddrPort());
         return {};
@@ -637,7 +639,7 @@ std::unique_ptr<Sock> Proxy::Connect() const
     if (!m_is_unix_socket) return ConnectDirectly(proxy, /*manual_connection=*/true);
 
 #if HAVE_SOCKADDR_UN
-    auto sock = CreateSock(AF_UNIX);
+    auto sock = CreateSock(AF_UNIX, SOCK_STREAM, 0);
     if (!sock) {
         LogPrintLevel(BCLog::NET, BCLog::Level::Error, "Cannot create a socket for connecting to %s\n", m_unix_socket_path);
         return {};

src/netbase.h

@@ -262,16 +262,18 @@ CService LookupNumeric(const std::string& name, uint16_t portDefault = 0, DNSLoo
 CSubNet LookupSubNet(const std::string& subnet_str);
 
 /**
- * Create a TCP or UNIX socket in the given address family.
- * @param[in] address_family to use for the socket.
+ * Create a real socket from the operating system.
+ * @param[in] domain Communications domain, first argument to the socket(2) syscall.
+ * @param[in] type Type of the socket, second argument to the socket(2) syscall.
+ * @param[in] protocol The particular protocol to be used with the socket, third argument to the socket(2) syscall.
  * @return pointer to the created Sock object or unique_ptr that owns nothing in case of failure
  */
-std::unique_ptr<Sock> CreateSockOS(sa_family_t address_family);
+std::unique_ptr<Sock> CreateSockOS(int domain, int type, int protocol);
 
 /**
  * Socket factory. Defaults to `CreateSockOS()`, but can be overridden by unit tests.
  */
-extern std::function<std::unique_ptr<Sock>(const sa_family_t&)> CreateSock;
+extern std::function<std::unique_ptr<Sock>(int, int, int)> CreateSock;
 
 /**
  * Create a socket and try to connect to the specified service.

src/test/fuzz/fuzz.cpp

@@ -101,8 +101,9 @@ void ResetCoverageCounters() {}
 
 void initialize()
 {
-    // Terminate immediately if a fuzzing harness ever tries to create a TCP socket.
-    CreateSock = [](const sa_family_t&) -> std::unique_ptr<Sock> { std::terminate(); };
+    // Terminate immediately if a fuzzing harness ever tries to create a socket.
+    // Individual tests can override this by pointing CreateSock to a mocked alternative.
+    CreateSock = [](int, int, int) -> std::unique_ptr<Sock> { std::terminate(); };
 
     // Terminate immediately if a fuzzing harness ever tries to perform a DNS lookup.
     g_dns_lookup = [](const std::string& name, bool allow_lookup) {

src/test/fuzz/i2p.cpp

@@ -27,7 +27,7 @@ FUZZ_TARGET(i2p, .init = initialize_i2p)
 
     // Mock CreateSock() to create FuzzedSock.
     auto CreateSockOrig = CreateSock;
-    CreateSock = [&fuzzed_data_provider](const sa_family_t&) {
+    CreateSock = [&fuzzed_data_provider](int, int, int) {
         return std::make_unique<FuzzedSock>(fuzzed_data_provider);
     };
 

src/test/i2p_tests.cpp

@@ -39,15 +39,14 @@ public:
 
 private:
     const BCLog::Level m_prev_log_level;
-    const std::function<std::unique_ptr<Sock>(const sa_family_t&)> m_create_sock_orig;
+    const decltype(CreateSock) m_create_sock_orig;
 };
 
 BOOST_FIXTURE_TEST_SUITE(i2p_tests, EnvTestingSetup)
 
 BOOST_AUTO_TEST_CASE(unlimited_recv)
 {
-    // Mock CreateSock() to create MockSock.
-    CreateSock = [](const sa_family_t&) {
+    CreateSock = [](int, int, int) {
         return std::make_unique<StaticContentsSock>(std::string(i2p::sam::MAX_MSG_SIZE + 1, 'a'));
     };
 
@@ -69,7 +68,7 @@ BOOST_AUTO_TEST_CASE(unlimited_recv)
 BOOST_AUTO_TEST_CASE(listen_ok_accept_fail)
 {
     size_t num_sockets{0};
-    CreateSock = [&num_sockets](const sa_family_t&) {
+    CreateSock = [&num_sockets](int, int, int) {
         // clang-format off
         ++num_sockets;
         // First socket is the control socket for creating the session.
@@ -133,9 +132,7 @@ BOOST_AUTO_TEST_CASE(listen_ok_accept_fail)
 
 BOOST_AUTO_TEST_CASE(damaged_private_key)
 {
-    const auto CreateSockOrig = CreateSock;
-
-    CreateSock = [](const sa_family_t&) {
+    CreateSock = [](int, int, int) {
         return std::make_unique<StaticContentsSock>("HELLO REPLY RESULT=OK VERSION=3.1\n"
                                                     "SESSION STATUS RESULT=OK DESTINATION=\n");
     };
@@ -172,8 +169,6 @@ BOOST_AUTO_TEST_CASE(damaged_private_key)
             BOOST_CHECK(!session.Connect(CService{}, conn, proxy_error));
         }
     }
-
-    CreateSock = CreateSockOrig;
 }
 
 BOOST_AUTO_TEST_SUITE_END()