Added protocol type constants.
diff --git a/include/winsock2.h b/include/winsock2.h
index 566263b..2ba234a 100644
--- a/include/winsock2.h
+++ b/include/winsock2.h
@@ -76,6 +76,21 @@
#define WS_SO_CONDITIONAL_ACCEPT 0x3002
#endif
+/* protocol types */
+
+#ifndef USE_WS_PREFIX
+#define SOCK_STREAM 1
+#define SOCK_DGRAM 2
+#define SOCK_RAW 3
+#define SOCK_RDM 4
+#define SOCK_SEQPACKET 5
+#else /* USE_WS_PREFIX */
+#define WS_SOCK_STREAM 1
+#define WS_SOCK_DGRAM 2
+#define WS_SOCK_RAW 3
+#define WS_SOCK_RDM 4
+#define WS_SOCK_SEQPACKET 5
+#endif /* USE_WS_PREFIX */
/* option flags per socket */
