X-Git-Url: http://git.tuebingen.mpg.de/?p=paraslash.git;a=blobdiff_plain;f=net.c;h=be637ec7a5e24e7d1856ed21370139d7a05c5a2c;hp=59b7f367fb2f119e338d9411f2060a71b39209fc;hb=6b935f552ebfe3a0a83ec9367deb2f42c1aff252;hpb=8dab386f87d2998fd26126600ca7faf56d5a35d1

diff --git a/net.c b/net.c
index 59b7f367..be637ec7 100644
--- a/net.c
+++ b/net.c
@@ -521,6 +521,14 @@ static socklen_t salen(const struct sockaddr *sa)
 		: sizeof(struct sockaddr_in);
 }
 
+/** True if @ss holds a v6-mapped-v4 address (RFC 4291, 2.5.5.2) */
+static bool SS_IS_ADDR_V4MAPPED(const struct sockaddr_storage *ss)
+{
+	const struct sockaddr_in6 *ia6 = (const struct sockaddr_in6 *)ss;
+
+	return ss->ss_family == AF_INET6 && IN6_IS_ADDR_V4MAPPED(&ia6->sin6_addr);
+}
+
 /**
  * Process IPv4/v6 address, turn v6-mapped-v4 address into normal IPv4 address.
  * \param ss Container of IPv4/6 address.
@@ -531,11 +539,10 @@ static socklen_t salen(const struct sockaddr *sa)
 static const struct sockaddr *
 normalize_ip_address(const struct sockaddr_storage *ss)
 {
-	const struct sockaddr_in6 *ia6 = (const struct sockaddr_in6 *)ss;
-
 	assert(ss->ss_family == AF_INET || ss->ss_family == AF_INET6);
 
-	if (ss->ss_family == AF_INET6 && IN6_IS_ADDR_V4MAPPED(&ia6->sin6_addr)) {
+	if (SS_IS_ADDR_V4MAPPED(ss)) {
+		const struct sockaddr_in6 *ia6 = (const struct sockaddr_in6 *)ss;
 		static struct sockaddr_in ia;
 
 		ia.sin_family = AF_INET;
@@ -546,30 +553,73 @@ normalize_ip_address(const struct sockaddr_storage *ss)
 	return (const struct sockaddr *)ss;
 }
 
+/**
+ * Generic/fallback MTU values
+ *
+ * These are taken from RFC 1122, RFC 2460, and RFC 5405.
+ * - RFC 1122, 3.3.3 defines EMTU_S ("Effective MTU for sending") and recommends
+ *   to use an EMTU_S size of of 576 bytes if the IPv4 path MTU is unknown;
+ * - RFC 2460, 5. requires a minimum IPv6 MTU of 1280 bytes;
+ * - RFC 5405, 3.2 recommends that if path MTU discovery is not done,
+ *   UDP senders should use the respective minimum values of EMTU_S.
+ */
+static inline int generic_mtu(const int af_type)
+{
+	return af_type == AF_INET6 ? 1280 : 576;
+}
+
+/** Crude approximation of IP header overhead - neglecting options. */
+static inline int estimated_header_overhead(const int af_type)
+{
+	return af_type == AF_INET6 ? 40 : 20;
+}
+
+/**
+ * Maximum transport-layer message size (MMS_S) as per RFC 1122, 3.3.3
+ * Socket must be connected.
+ */
+int generic_max_transport_msg_size(int sockfd)
+{
+	struct sockaddr_storage ss;
+	socklen_t sslen = sizeof(ss);
+	int af_type = AF_INET;
+
+	if (getpeername(sockfd, (struct sockaddr *)&ss, &sslen) < 0) {
+		PARA_ERROR_LOG("can not determine remote address type: %s\n",
+				strerror(errno));
+	} else if (!SS_IS_ADDR_V4MAPPED(&ss)) {
+		af_type = ss.ss_family;
+	}
+	return generic_mtu(af_type) - estimated_header_overhead(af_type);
+}
+
 /**
  * Print numeric host and port number (beware - uses static char).
  *
  * \param sa The IPv4/IPv6 socket address to use.
  *
+ * \return Host string in numeric host:port format, \sa parse_url().
  * \sa getnameinfo(3), services(5), nsswitch.conf(5)
  */
 static char *host_and_port(const struct sockaddr_storage *ss)
 {
 	const struct sockaddr *sa = normalize_ip_address(ss);
 	char hbuf[NI_MAXHOST], sbuf[NI_MAXSERV];
-	static char output[sizeof(hbuf) + sizeof(sbuf) + 2];
+	static char output[sizeof(hbuf) + sizeof(sbuf) + 4];
 	int ret;
 
 	ret = getnameinfo(sa, salen(sa),
 			  hbuf, sizeof(hbuf),
 			  sbuf, sizeof(sbuf),
-			  NI_NUMERICHOST);
-	if (ret == 0) {
-		snprintf(output, sizeof(output), "%s#%s", hbuf, sbuf);
-	} else {
+			  NI_NUMERICHOST | NI_NUMERICSERV);
+	if (ret) {
 		snprintf(output, sizeof(output), "(unknown)");
 		PARA_WARNING_LOG("hostname lookup error (%s).\n",
 				 gai_strerror(ret));
+	} else if (sa->sa_family == AF_INET6) {
+		snprintf(output, sizeof(output), "[%s]:%s", hbuf, sbuf);
+	} else {
+		snprintf(output, sizeof(output), "%s:%s", hbuf, sbuf);
 	}
 	return output;
 }