add sendto hook to handle MSG_FASTOPEN flag

tests/test_sendto.c

@@ -0,0 +1,62 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include <string.h>
+#include <sys/types.h>
+#include <sys/socket.h>
+#include <netinet/in.h>
+#include <netdb.h>
+
+void error(const char *msg)
+{
+	perror(msg);
+	exit(1);
+}
+
+int main(int argc, char *argv[])
+{
+	if (argc < 4) {
+		printf("Usage: %s host port method(connect or sendto)\n", argv[0]);
+		return 1;
+	}
+	const char *hostname = argv[1];
+	const int portno = atoi(argv[2]);
+	const char *method = argv[3];
+	char request[BUFSIZ];
+	sprintf(request, "GET / HTTP/1.0\r\nHost: %s\r\n\r\n", hostname);
+	int sockfd, n;
+	struct sockaddr_in serv_addr;
+	struct hostent *server;
+
+	char buffer[BUFSIZ];
+	sockfd = socket(AF_INET, SOCK_STREAM, 0);
+	if (sockfd < 0) error("ERROR opening socket");
+	server = gethostbyname(hostname);
+	if (server == NULL) {
+		fprintf(stderr, "%s: no such host\n", hostname);
+		return 1;
+	}
+	memset(&serv_addr, 0, sizeof(serv_addr));
+	serv_addr.sin_family = AF_INET;
+	memcpy(&serv_addr.sin_addr.s_addr, server->h_addr, server->h_length);
+	serv_addr.sin_port = htons(portno);
+	if (!strcmp(method, "connect")) {
+	  if (connect(sockfd, (struct sockaddr *)&serv_addr, sizeof(serv_addr)) < 0)
+		  error("connect");
+	  n = send(sockfd, request, strlen(request), 0);
+	} else if (!strcmp(method, "sendto")) {
+	  n = sendto(sockfd, request, strlen(request), MSG_FASTOPEN, (struct sockaddr *)&serv_addr, sizeof(serv_addr));
+	} else {
+	  printf("Unknown method %s\n", method);
+	  return 1;
+	}
+	if (n < 0)
+		 error("send");
+	memset(buffer, 0, BUFSIZ);
+	n = read(sockfd, buffer, BUFSIZ - 1);
+	if (n < 0)
+		 error("ERROR reading from socket");
+	printf("%s\n", buffer);
+	close(sockfd);
+	return 0;
+}