windows: Implement socketpair() using TCP sockets

src/libstrongswan/utils/windows.c

@@ -15,6 +15,8 @@
 
 #include "utils.h"
 
+#include <errno.h>
+
 /**
  * See header
  */
@@ -33,3 +35,65 @@ void windows_deinit()
 {
 	WSACleanup();
 }
+
+/**
+ * See header
+ */
+int socketpair(int domain, int type, int protocol, int sv[2])
+{
+	struct sockaddr_in addr = {
+		.sin_family = AF_INET,
+		.sin_addr.s_addr = htonl(INADDR_LOOPBACK),
+	};
+	socklen_t len = sizeof(addr);
+	int s, c, sc;
+	BOOL on;
+
+	/* We don't check domain for AF_INET, as we use it as replacement for
+	 * AF_UNIX. */
+	if (type != SOCK_STREAM)
+	{
+		errno = EINVAL;
+		return -1;
+	}
+	if (protocol != 0 && protocol != IPPROTO_TCP)
+	{
+		errno = EINVAL;
+		return -1;
+	}
+	s = socket(AF_INET, SOCK_STREAM, IPPROTO_TCP);
+	if (s == -1)
+	{
+		return -1;
+	}
+	c = socket(AF_INET, SOCK_STREAM, IPPROTO_TCP);
+	if (c == -1)
+	{
+		closesocket(c);
+		return -1;
+	}
+	if (bind(s, (struct sockaddr*)&addr, sizeof(addr)) == 0 &&
+		getsockname(s,(struct sockaddr*)&addr, &len) == 0 &&
+		listen(s, 0) == 0 &&
+		connect(c, (struct sockaddr*)&addr, sizeof(addr)) == 0)
+	{
+		sc = accept(s, NULL, NULL);
+		if (sc > 0)
+		{
+			closesocket(s);
+			s = sc;
+			if (setsockopt(s, IPPROTO_TCP, TCP_NODELAY,
+						   (void*)&on, sizeof(on)) == 0 &&
+				setsockopt(c, IPPROTO_TCP, TCP_NODELAY,
+						   (void*)&on, sizeof(on)) == 0)
+			{
+				sv[0] = s;
+				sv[1] = c;
+				return 0;
+			}
+		}
+	}
+	closesocket(s);
+	closesocket(c);
+	return -1;
+}

src/libstrongswan/utils/windows.h

@@ -246,6 +246,11 @@ static inline int dlclose(void *handle)
 	return FreeLibrary((HMODULE)handle);
 }
 
+/**
+ * socketpair(2) for SOCK_STREAM, uses TCP on loopback
+ */
+int socketpair(int domain, int type, int protocol, int sv[2]);
+
 /* Windows does not support "ll" format printf length modifiers. Mingw
  * therefore maps these to the Windows specific I64 length modifier. That
  * won't work for us, as we use our own printf backend on Windows, which works