windows tcp: Lookup extended TCP function pointers at startup

This avoids the need for a lock during listener or dialer initialization,
and it avoids the need to carry these pointers on those objects.
It also eliminates a potential failure case "post startup".

1 files changed, 70 insertions, 1 deletions

diff --git a/src/platform/windows/win_tcp.c b/src/platform/windows/win_tcp.c
index 2ab6be0f..42667dea 100644
--- a/src/platform/windows/win_tcp.c
+++ b/src/platform/windows/win_tcp.c
@@ -1,5 +1,5 @@
 //
-// Copyright 2018 Staysail Systems, Inc. <info@staysail.tech>
+// Copyright 2024 Staysail Systems, Inc. <info@staysail.tech>
 // Copyright 2018 Capitar IT Group BV <info@capitar.com>
 //
 // This software is supplied under the terms of the MIT License, a
@@ -15,18 +15,87 @@
 #include <malloc.h>
 #include <stdio.h>
 
+static LPFN_ACCEPTEX             acceptex;
+static LPFN_GETACCEPTEXSOCKADDRS getacceptexsockaddrs;
+static LPFN_CONNECTEX            connectex;
+
 int
 nni_win_tcp_sysinit(void)
 {
+	int rv;
+
 	WSADATA data;
+
 	if (WSAStartup(MAKEWORD(2, 2), &data) != 0) {
 		NNI_ASSERT(LOBYTE(data.wVersion) == 2);
 		NNI_ASSERT(HIBYTE(data.wVersion) == 2);
 		return (nni_win_error(GetLastError()));
 	}
+
+	DWORD nbytes;
+	GUID  guid1 = WSAID_ACCEPTEX;
+	GUID  guid2 = WSAID_GETACCEPTEXSOCKADDRS;
+	GUID  guid3 = WSAID_CONNECTEX;
+
+	SOCKET s = socket(AF_INET6, SOCK_STREAM, IPPROTO_TCP);
+	if (s == INVALID_SOCKET) {
+		rv = nni_win_error(GetLastError());
+		WSACleanup();
+		return (rv);
+	}
+	if ((WSAIoctl(s, SIO_GET_EXTENSION_FUNCTION_POINTER, &guid1,
+	         sizeof(guid1), &acceptex, sizeof(acceptex), &nbytes, NULL,
+	         NULL) == SOCKET_ERROR) ||
+	    (WSAIoctl(s, SIO_GET_EXTENSION_FUNCTION_POINTER, &guid2,
+	         sizeof(guid2), &getacceptexsockaddrs,
+	         sizeof(getacceptexsockaddrs), &nbytes, NULL,
+	         NULL) == SOCKET_ERROR) ||
+	    (WSAIoctl(s, SIO_GET_EXTENSION_FUNCTION_POINTER, &guid3,
+	         sizeof(guid3), &connectex, sizeof(connectex), &nbytes, NULL,
+	         NULL) == SOCKET_ERROR)) {
+		rv = nni_win_error(GetLastError());
+		closesocket(s);
+		WSACleanup();
+		return (rv);
+	}
+
+	closesocket(s);
 	return (0);
 }
 
+int
+nni_win_acceptex(SOCKET listen, SOCKET child, void *buf, LPOVERLAPPED olpd)
+{
+	DWORD cnt = 0;
+	return (acceptex(listen, child, buf, 0, 256, 256, &cnt, olpd));
+}
+
+// This is called after a socket is accepted for the connection, and the buffer
+// contains the peers socket addresses.  It is is kind of weird, windows
+// specific, and must be called only after acceptex.  The caller should call
+// setsockopt(s, SOL_SOCKET, SO_UPDATE_ACCEPT_CONTEXT) after calling this.
+void
+nni_win_get_acceptex_sockaddrs(
+    void *buf, SOCKADDR_STORAGE *self, SOCKADDR_STORAGE *peer)
+{
+	SOCKADDR *self_p;
+	SOCKADDR *peer_p;
+	int       self_len;
+	int       peer_len;
+
+	getacceptexsockaddrs(
+	    buf, 0, 256, 256, &self_p, &self_len, &peer_p, &peer_len);
+
+	(void) memcpy(self, self_p, self_len);
+	(void) memcpy(peer, peer_p, peer_len);
+}
+
+int
+nni_win_connectex(SOCKET s, SOCKADDR *peer, int peer_len, LPOVERLAPPED olpd)
+{
+	return (connectex(s, peer, peer_len, NULL, 0, NULL, olpd));
+}
+
 void
 nni_win_tcp_sysfini(void)
 {