Make the UDP socket use the right source address

configure.ac

@@ -361,6 +361,34 @@ if test "x$iperf3_cv_header_dontfragment" = "xyes"; then
     AC_DEFINE([HAVE_DONT_FRAGMENT], [1], [Have IP_MTU_DISCOVER/IP_DONTFRAG/IP_DONTFRAGMENT sockopt.])
 fi
 
+# Check for IP_PKTINFO (Linux only)
+AC_CACHE_CHECK([IP_PKTINFO socket option],
+[iperf3_cv_header_ip_pktinfo],
+AC_COMPILE_IFELSE(
+  [AC_LANG_PROGRAM([[#include <netinet/in.h>]],
+		   [[int foo = IP_PKTINFO;]])],
+  iperf3_cv_header_ip_pktinfo=yes,
+  iperf3_cv_header_ip_pktinfo=no))
+if test "x$iperf3_cv_header_ip_pktinfo" = "xyes"; then
+    AC_DEFINE([HAVE_IP_PKTINFO], [1], [Have IP_PKTINFO sockopt.])
+fi
+
+# Check for IP_RECVDSTADDR (BSD?)
+AC_CACHE_CHECK([IP_RECVDSTADDR socket option],
+[iperf3_cv_header_ip_recvdstaddr],
+AC_COMPILE_IFELSE(
+  [AC_LANG_PROGRAM([[#include <netinet/in.h>]],
+		   [[int foo = IP_RECVDSTADDR;]])],
+  iperf3_cv_header_ip_recvdstaddr=yes,
+  iperf3_cv_header_ip_recvdstaddr=no))
+if test "x$iperf3_cv_header_ip_recvdstaddr" = "xyes"; then
+    AC_DEFINE([HAVE_IP_RECVDSTADDR], [1], [Have IP_RECVDSTADDR sockopt.])
+fi
+
+if test "x$iperf3_cv_header_ip_pktinfo$iperf3_cv_header_ip_recvdstaddr" = "xnono"; then
+    AC_MSG_ERROR([neither IP_PKTINFO nor IP_RECVDSTADDR is available])
+fi
+
 #
 # Check for tcpi_snd_wnd in struct tcp_info
 #

src/iperf_udp.c

@@ -522,25 +522,91 @@ iperf_udp_gro(struct iperf_test *test, int s)
 int
 iperf_udp_accept(struct iperf_test *test)
 {
-    struct sockaddr_storage sa_peer;
+    struct sockaddr_storage	sa_peer, sa_local;
     unsigned int buf;
-    socklen_t len;
+    socklen_t			len, len_local;
     int       sz, s;
     int	      rc;
-
-    /*
-     * Get the current outstanding socket.  This socket will be used to handle
-     * data transfers and a new "listening" socket will be created.
-     */
-    s = test->prot_listener;
+    char			cbuffer[
+#ifdef HAVE_IP_PKTINFO
+					CMSG_SPACE(sizeof (struct in_pktinfo)
+					 > sizeof (struct in6_pktinfo)?
+					 sizeof (struct in_pktinfo):
+					 sizeof (struct in6_pktinfo))
+#elif defined(HAVE_IP_RECVDSTADDR)
+					CMSG_SPACE(sizeof (struct in_addr)
+					 > sizeof (struct in6_pktinfo)?
+					 sizeof (struct in_addr):
+					 sizeof (struct in6_pktinfo))
+#endif
+				];
+    struct cmsghdr		*cm;
+    struct msghdr		msg;
+    struct iovec		iov;
 
     /*
      * Grab the UDP packet sent by the client.  From that we can extract the
      * client's address, and then use that information to bind the remote side
      * of the socket to the client.
      */
-    len = sizeof(sa_peer);
-    if ((sz = recvfrom(test->prot_listener, &buf, sizeof(buf), 0, (struct sockaddr *) &sa_peer, &len)) < 0) {
+    len = len_local = sizeof(sa_peer);
+
+    memset(cbuffer, 0, sizeof cbuffer);
+
+    msg.msg_name       = &sa_peer;
+    msg.msg_namelen    = len;
+    msg.msg_iov        = &iov;
+    msg.msg_iovlen     = 1;
+    msg.msg_control    = cbuffer;
+    msg.msg_controllen = sizeof cbuffer;
+    msg.msg_flags      = 0;
+
+    iov.iov_base = &buf;
+    iov.iov_len  = sizeof buf;
+
+    /* Get the address of the local socket to determine the domain and port. */
+    if (getsockname(test->prot_listener, (struct sockaddr *) &sa_local,
+		    &len_local) < 0) {
+	i_errno = IESTREAMACCEPT;
+	return -1;
+    }
+
+    if ((sz = recvmsg(test->prot_listener, &msg, 0)) < 0) {
+	i_errno = IESTREAMACCEPT;
+	return -1;
+    }
+
+    /* Parse the retrieved ancillary data and retrieve the incoming
+       packet's destination address. */
+    for (cm = CMSG_FIRSTHDR(&msg); cm != NULL; cm = CMSG_NXTHDR(&msg, cm))
+	switch (sa_local.ss_family) {
+	case AF_INET:
+#ifdef HAVE_IP_PKTINFO
+	    if (cm->cmsg_level == IPPROTO_IP && cm->cmsg_type == IP_PKTINFO
+		&& cm->cmsg_len >= CMSG_LEN(sizeof (struct in_pktinfo)))
+	      memcpy(&((struct sockaddr_in *) &sa_local)->sin_addr,
+		     CMSG_DATA(cm) + offsetof(struct in_pktinfo, ipi_addr),
+		     sizeof (struct in_addr));
+#elif defined(HAVE_IP_RECVDSTADDR)
+	    if (cm->cmsg_level == IPPROTO_IP && cm->cmsg_type == IP_RECVDSTADDR
+		&& cm->cmsg_len >= CMSG_LEN(sizeof (struct in_addr)))
+	      memcpy(&((struct sockaddr_in *) &sa_local)->sin_addr,
+		     CMSG_DATA(cm), sizeof (struct in_addr));
+#endif
+	    break;
+	case AF_INET6:
+	    if (cm->cmsg_level == IPPROTO_IPV6 && cm->cmsg_type == IPV6_PKTINFO
+		&& cm->cmsg_len >= CMSG_LEN(sizeof (struct in6_pktinfo)))
+	      memcpy(&((struct sockaddr_in6 *) &sa_local)->sin6_addr,
+		     CMSG_DATA(cm) + offsetof(struct in6_pktinfo, ipi6_addr),
+		     sizeof (struct in6_addr));
+	}
+
+    /* Open and bind the session socket. */
+    s = netannounce_sockaddr(test->settings->domain, Pudp,
+			     (struct sockaddr *) &sa_local, len_local,
+			     test->bind_dev, 0);
+    if (s < 0) {
         i_errno = IESTREAMACCEPT;
         return -1;
     }
@@ -602,16 +668,6 @@ iperf_udp_accept(struct iperf_test *test)
 	}
     }
 
-    /*
-     * Create a new "listening" socket to replace the one we were using before.
-     */
-    FD_CLR(test->prot_listener, &test->read_set); // No control messages from old listener
-    test->prot_listener = netannounce(test->settings->domain, Pudp, test->bind_address, test->bind_dev, test->server_port);
-    if (test->prot_listener < 0) {
-        i_errno = IESTREAMLISTEN;
-        return -1;
-    }
-
     FD_SET(test->prot_listener, &test->read_set);
     test->max_fd = (test->max_fd < test->prot_listener) ? test->prot_listener : test->max_fd;
 

src/net.c

@@ -290,52 +290,22 @@ netdial(int domain, int proto, const char *local, const char *bind_dev, int loca
 /***************************************************************/
 
 int
-netannounce(int domain, int proto, const char *local, const char *bind_dev, int port)
+netannounce_sockaddr(int domain, int proto, const struct sockaddr *local,
+		     socklen_t local_len, const char *bind_dev, int is_listen)
 {
-    struct addrinfo hints, *res;
-    char portstr[6];
     int s, opt, saved_errno;
 
-    snprintf(portstr, 6, "%d", port);
-    memset(&hints, 0, sizeof(hints));
-    /*
-     * If binding to the wildcard address with no explicit address
-     * family specified, then force us to get an AF_INET6 socket.  On
-     * CentOS 6 and MacOS, getaddrinfo(3) with AF_UNSPEC in ai_family,
-     * and ai_flags containing AI_PASSIVE returns a result structure
-     * with ai_family set to AF_INET, with the result that we create
-     * and bind an IPv4 address wildcard address and by default, we
-     * can't accept IPv6 connections.
-     *
-     * On FreeBSD, under the above circumstances, ai_family in the
-     * result structure is set to AF_INET6.
-     */
-    if (domain == AF_UNSPEC && !local) {
-	hints.ai_family = AF_INET6;
-    }
-    else {
-	hints.ai_family = domain;
-    }
-    hints.ai_socktype = proto;
-    hints.ai_flags = AI_PASSIVE;
-    if ((gerror = getaddrinfo(local, portstr, &hints, &res)) != 0)
+    s = socket(local->sa_family, proto, 0);
+    if (s < 0)
         return -1;
 
-    s = socket(res->ai_family, proto, 0);
-    if (s < 0) {
-	freeaddrinfo(res);
-        return -1;
-    }
-
     if (bind_dev) {
 #if defined(HAVE_SO_BINDTODEVICE)
-        if (setsockopt(s, SOL_SOCKET, SO_BINDTODEVICE,
-                       bind_dev, IFNAMSIZ) < 0)
+        if (setsockopt(s, SOL_SOCKET, SO_BINDTODEVICE, bind_dev, IFNAMSIZ) < 0)
 #endif // HAVE_SO_BINDTODEVICE
         {
             saved_errno = errno;
             close(s);
-            freeaddrinfo(res);
             errno = saved_errno;
             return -1;
         }
@@ -346,7 +316,6 @@ netannounce(int domain, int proto, const char *local, const char *bind_dev, int
 		   (char *) &opt, sizeof(opt)) < 0) {
 	saved_errno = errno;
 	close(s);
-	freeaddrinfo(res);
 	errno = saved_errno;
 	return -1;
     }
@@ -359,7 +328,7 @@ netannounce(int domain, int proto, const char *local, const char *bind_dev, int
      * even though it implements IPV6_V6ONLY.
      */
 #if defined(IPV6_V6ONLY) && !defined(__OpenBSD__)
-    if (res->ai_family == AF_INET6 && (domain == AF_UNSPEC || domain == AF_INET6)) {
+    if (local->sa_family == AF_INET6 && (domain == AF_UNSPEC || domain == AF_INET6)) {
 	if (domain == AF_UNSPEC)
 	    opt = 0;
 	else
@@ -368,22 +337,38 @@ netannounce(int domain, int proto, const char *local, const char *bind_dev, int
 		       (char *) &opt, sizeof(opt)) < 0) {
 	    saved_errno = errno;
 	    close(s);
-	    freeaddrinfo(res);
 	    errno = saved_errno;
 	    return -1;
 	}
     }
 #endif /* IPV6_V6ONLY */
 
-    if (bind(s, (struct sockaddr *) res->ai_addr, res->ai_addrlen) < 0) {
+    /* Request the passing of in_pktinfo/in6_pktinfo as ancillary data. */
+    if (is_listen && proto == SOCK_DGRAM) {
+	opt = 1;
+	if (setsockopt(s, local->sa_family == AF_INET6?
+		       IPPROTO_IPV6: IPPROTO_IP,
+		       local->sa_family == AF_INET6?
+		       IPV6_RECVPKTINFO:
+#ifdef HAVE_IP_PKTINFO
+		       IP_PKTINFO,
+#elif defined(HAVE_IP_RECVDSTADDR)
+		       IP_RECVDSTADDR,
+#endif
+		       &opt, sizeof opt) < 0) {
         saved_errno = errno;
         close(s);
-	freeaddrinfo(res);
         errno = saved_errno;
         return -1;
     }
+    }
 
-    freeaddrinfo(res);
+    if (bind(s, local, local_len) < 0) {
+	saved_errno = errno;
+	close(s);
+	errno = saved_errno;
+	return -1;
+    }
 
     if (proto == SOCK_STREAM) {
         if (listen(s, INT_MAX) < 0) {
@@ -397,6 +382,51 @@ netannounce(int domain, int proto, const char *local, const char *bind_dev, int
     return s;
 }
 
+int
+netannounce(int domain, int proto, const char *local, const char *bind_dev, int port)
+{
+    struct addrinfo hints, *res;
+    char portstr[6];
+    int s;
+
+    snprintf(portstr, 6, "%d", port);
+    memset(&hints, 0, sizeof(hints));
+    /*
+     * If binding to the wildcard address with no explicit address
+     * family specified, then force us to get an AF_INET6 socket.  On
+     * CentOS 6 and MacOS, getaddrinfo(3) with AF_UNSPEC in ai_family,
+     * and ai_flags containing AI_PASSIVE returns a result structure
+     * with ai_family set to AF_INET, with the result that we create
+     * and bind an IPv4 address wildcard address and by default, we
+     * can't accept IPv6 connections.
+     *
+     * On FreeBSD, under the above circumstances, ai_family in the
+     * result structure is set to AF_INET6.
+     */
+    if (domain == AF_UNSPEC && !local) {
+	hints.ai_family = AF_INET6;
+    }
+    else {
+	hints.ai_family = domain;
+    }
+    hints.ai_socktype = proto;
+    hints.ai_flags = AI_PASSIVE;
+    if ((gerror = getaddrinfo(local, portstr, &hints, &res)) != 0)
+	return -1;
+
+    s = netannounce_sockaddr(domain, proto,
+			     (struct sockaddr *) res->ai_addr,
+			     res->ai_addrlen, bind_dev, 1);
+    if (s < 0) {
+	freeaddrinfo(res);
+	return -1;
+    }
+
+    freeaddrinfo(res);
+
+    return s;
+}
+
 /*******************************************************************/
 /* Nread - reads 'count' bytes from a socket  */
 /********************************************************************/

src/net.h

@@ -30,6 +30,7 @@
 int timeout_connect(int s, const struct sockaddr *name, socklen_t namelen, int timeout);
 int create_socket(int domain, int type, int proto, const char *local, const char *bind_dev, int local_port, const char *server, int port, struct addrinfo **server_res_out);
 int netdial(int domain, int proto, const char *local, const char *bind_dev, int local_port, const char *server, int port, int timeout);
+int netannounce_sockaddr(int domain, int proto, const struct sockaddr *local, socklen_t local_len, const char *bind_dev, int is_listen);
 int netannounce(int domain, int proto, const char *local, const char *bind_dev, int port);
 int Nread(int fd, char *buf, size_t count, int prot);
 int Nrecv(int fd, char *buf, size_t count, int prot, int sock_opt);