slirp: fix guest network access with darwin host

On Darwin, connect, sendto and friends want the exact size of the sockaddr,
not more (and in particular, not sizeof(struct sockaddr_storaget))

This commit adds the sockaddr_size helper to be used when passing a sockaddr
size to such function, and makes use of it int sendto and connect calls.
Signed-off-by: NSamuel Thibault <samuel.thibault@ens-lyon.org>
Reviewed-by: NJohn Arbuckle <programmingkidx@gmail.com>
Signed-off-by: NPeter Maydell <peter.maydell@linaro.org>

slirp/ip_icmp.c

@@ -186,7 +186,7 @@ icmp_input(struct mbuf *m, int hlen)
       sotranslate_out(so, &addr);
 
       if(sendto(so->s, icmp_ping_msg, strlen(icmp_ping_msg), 0,
-		(struct sockaddr *)&addr, sizeof(addr)) == -1) {
+		(struct sockaddr *)&addr, sockaddr_size(&addr)) == -1) {
 	DEBUG_MISC((dfd,"icmp_input udp sendto tx errno = %d-%s\n",
 		    errno,strerror(errno)));
 	icmp_send_error(m, ICMP_UNREACH, ICMP_UNREACH_NET, 0, strerror(errno));

slirp/socket.c

@@ -627,7 +627,7 @@ sosendto(struct socket *so, struct mbuf *m)
 
 	/* Don't care what port we get */
 	ret = sendto(so->s, m->m_data, m->m_len, 0,
-		     (struct sockaddr *)&addr, sizeof(addr));
+		     (struct sockaddr *)&addr, sockaddr_size(&addr));
 	if (ret < 0)
 		return -1;
 

slirp/socket.h

@@ -122,6 +122,18 @@ static inline int sockaddr_equal(struct sockaddr_storage *a,
     return 0;
 }
 
+static inline socklen_t sockaddr_size(struct sockaddr_storage *a)
+{
+    switch (a->ss_family) {
+    case AF_INET:
+        return sizeof(struct sockaddr_in);
+    case AF_INET6:
+        return sizeof(struct sockaddr_in6);
+    default:
+        g_assert_not_reached();
+    }
+}
+
 struct socket *solookup(struct socket **, struct socket *,
         struct sockaddr_storage *, struct sockaddr_storage *);
 struct socket *socreate(Slirp *);

slirp/tcp_subr.c

@@ -413,7 +413,7 @@ int tcp_fconnect(struct socket *so, unsigned short af)
     sotranslate_out(so, &addr);
 
     /* We don't care what port we get */
-    ret = connect(s,(struct sockaddr *)&addr,sizeof (addr));
+    ret = connect(s, (struct sockaddr *)&addr, sockaddr_size(&addr));
 
     /*
      * If it's not in progress, it failed, so we just return 0,