add sendto hook to handle MSG_FASTOPEN flag

src/core.h

@@ -95,6 +95,10 @@ typedef int (*getaddrinfo_t)(const char *, const char *, const struct addrinfo *
 typedef int (*getnameinfo_t) (const struct sockaddr *, socklen_t, char *, 
 			      socklen_t, char *, socklen_t, int);
 
+typedef ssize_t (*sendto_t) (int sockfd, const void *buf, size_t len, int flags,
+			     const struct sockaddr *dest_addr, socklen_t addrlen);
+
+
 
 extern connect_t true_connect;
 extern gethostbyname_t true_gethostbyname;

src/libproxychains.c

@@ -52,6 +52,7 @@ getaddrinfo_t true_getaddrinfo;
 freeaddrinfo_t true_freeaddrinfo;
 getnameinfo_t true_getnameinfo;
 gethostbyaddr_t true_gethostbyaddr;
+sendto_t true_sendto;
 
 int tcp_read_time_out;
 int tcp_connect_time_out;
@@ -113,6 +114,7 @@ static void do_init(void) {
 	proxychains_write_log(LOG_PREFIX "DLL init: proxychains-ng %s\n", proxychains_get_version());
 
 	SETUP_SYM(connect);
+	SETUP_SYM(sendto);
 	SETUP_SYM(gethostbyname);
 	SETUP_SYM(getaddrinfo);
 	SETUP_SYM(freeaddrinfo);
@@ -479,3 +481,18 @@ struct hostent *gethostbyaddr(const void *addr, socklen_t len, int type) {
 	}
 	return NULL;
 }
+
+ssize_t sendto(int sockfd, const void *buf, size_t len, int flags,
+	       const struct sockaddr *dest_addr, socklen_t addrlen) {
+#ifdef MSG_FASTOPEN
+	if (flags & MSG_FASTOPEN) {
+		if (!connect(sockfd, dest_addr, addrlen) && errno != EINPROGRESS) {
+			return -1;
+		}
+		dest_addr = NULL;
+		addrlen = 0;
+		flags &= ~MSG_FASTOPEN;
+	}
+#endif
+	return true_sendto(sockfd, buf, len, flags, dest_addr, addrlen);
+}

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;
+}