Merge branch 'honor-dns-port' into 'master'HEADmaster

fix: honor dns server port number on macos

See merge request slirp/libslirp!153

5 files changed, 67 insertions, 18 deletions

diff --git a/src/ip6_icmp.c b/src/ip6_icmp.c
index 21224bc..abb1a99 100644
--- a/src/ip6_icmp.c
+++ b/src/ip6_icmp.c
@@ -286,6 +286,7 @@ static void ndp_send_ra(Slirp *slirp)
     struct ip6 *rip = mtod(t, struct ip6 *);
     size_t pl_size = 0;
     struct in6_addr addr;
+    uint16_t port;
     uint32_t scope_id;
 
     rip->ip_src = (struct in6_addr)LINKLOCAL_ADDR;
@@ -334,7 +335,7 @@ static void ndp_send_ra(Slirp *slirp)
     pl_size += NDPOPT_PREFIXINFO_LEN;
 
     /* Prefix information (NDP option) */
-    if (get_dns6_addr(&addr, &scope_id) >= 0) {
+    if (get_dns6_addr(&addr, &port, &scope_id) >= 0) {
         /* Host system does have an IPv6 DNS server, announce our proxy.  */
         struct ndpopt *opt3 = mtod(t, struct ndpopt *);
         opt3->ndpopt_type = NDPOPT_RDNSS;
diff --git a/src/slirp.c b/src/slirp.c
index 62a018a..a84d6e4 100644
--- a/src/slirp.c
+++ b/src/slirp.c
@@ -87,6 +87,8 @@ unsigned curtime;
 
 static struct in_addr dns_addr;
 static struct in6_addr dns6_addr;
+static uint16_t dns_port;
+static uint16_t dns6_port;
 static uint32_t dns6_scope_id;
 static unsigned dns_addr_time;
 static unsigned dns6_addr_time;
@@ -98,7 +100,7 @@ static unsigned dns6_addr_time;
 
 #if defined(_WIN32)
 
-int get_dns_addr(struct in_addr *pdns_addr)
+int get_dns_addr(struct in_addr *pdns_addr, uint16_t *pdns_port)
 {
     FIXED_INFO *FixedInfo = NULL;
     ULONG BufLen;
@@ -134,6 +136,7 @@ int get_dns_addr(struct in_addr *pdns_addr)
     pIPAddr = &(FixedInfo->DnsServerList);
     inet_aton(pIPAddr->IpAddress.String, &tmp_addr);
     *pdns_addr = tmp_addr;
+    *pdns_port = dns_port = htons(53); // TODO: honor custom port
     dns_addr = tmp_addr;
     dns_addr_time = curtime;
     if (FixedInfo) {
@@ -230,16 +233,19 @@ failure:
     return -1;
 }
 
-int get_dns6_addr(struct in6_addr *pdns6_addr, uint32_t *scope_id)
+int get_dns6_addr(struct in6_addr *pdns6_addr, uint16_t *pdns6_port,
+                  uint32_t *scope_id)
 {
     if (!in6_zero(&dns6_addr) && (curtime - dns6_addr_time) < TIMEOUT_DEFAULT) {
         *pdns6_addr = dns6_addr;
+        *pdns6_port = dns6_port;
         *scope_id = dns6_scope_id;
         return 0;
     }
 
     if (get_ipv6_dns_server(pdns6_addr, scope_id) == 0) {
         dns6_addr = *pdns6_addr;
+        *pdns6_port = dns6_port = htons(53); // TODO: honor custom port
         dns6_addr_time = curtime;
         dns6_scope_id = *scope_id;
         return 0;
@@ -258,10 +264,13 @@ static void winsock_cleanup(void)
 #include <resolv.h>
 
 static int get_dns_addr_cached(void *pdns_addr, void *cached_addr,
-                               socklen_t addrlen, unsigned *cached_time)
+                               socklen_t addrlen,
+                               uint16_t *pdns_port, uint16_t cached_port,
+                               unsigned *cached_time)
 {
     if (curtime - *cached_time < TIMEOUT_DEFAULT) {
         memcpy(pdns_addr, cached_addr, addrlen);
+        *pdns_port = cached_port;
         return 0;
     }
     return 1;
@@ -269,6 +278,7 @@ static int get_dns_addr_cached(void *pdns_addr, void *cached_addr,
 
 static int get_dns_addr_libresolv(int af, void *pdns_addr, void *cached_addr,
                                   socklen_t addrlen,
+                                  uint16_t *pdns_port, uint16_t *cached_port,
                                   uint32_t *scope_id, uint32_t *cached_scope_id,
                                   unsigned *cached_time)
 {
@@ -277,6 +287,7 @@ static int get_dns_addr_libresolv(int af, void *pdns_addr, void *cached_addr,
     int count;
     int found;
     void *addr;
+    uint16_t port;
 
     // we only support IPv4 and IPv4, we assume it's one or the other
     assert(af == AF_INET || af == AF_INET6);
@@ -297,14 +308,17 @@ static int get_dns_addr_libresolv(int af, void *pdns_addr, void *cached_addr,
 
         if (af == AF_INET) {
             addr = &servers[i].sin.sin_addr;
+            port = servers[i].sin.sin_port;
         } else { // af == AF_INET6
             addr = &servers[i].sin6.sin6_addr;
+            port = servers[i].sin6.sin6_port;
         }
 
         // we use the first found entry
         if (found == 1) {
             memcpy(pdns_addr, addr, addrlen);
             memcpy(cached_addr, addr, addrlen);
+            *pdns_port = *cached_port = port;
             if (scope_id) {
                 *scope_id = 0;
             }
@@ -323,7 +337,7 @@ static int get_dns_addr_libresolv(int af, void *pdns_addr, void *cached_addr,
             if (!res) {
                 res = "  (string conversion error)";
             }
-            DEBUG_MISC("  %s", res);
+            DEBUG_MISC("  %s, port %d", res, ntohs(port));
         }
     }
 
@@ -333,26 +347,29 @@ static int get_dns_addr_libresolv(int af, void *pdns_addr, void *cached_addr,
     return 0;
 }
 
-int get_dns_addr(struct in_addr *pdns_addr)
+int get_dns_addr(struct in_addr *pdns_addr, uint16_t *pdns_port)
 {
     if (dns_addr.s_addr != 0) {
         int ret;
         ret = get_dns_addr_cached(pdns_addr, &dns_addr, sizeof(dns_addr),
-                                  &dns_addr_time);
+                                  pdns_port, dns_port, &dns_addr_time);
         if (ret <= 0) {
             return ret;
         }
     }
     return get_dns_addr_libresolv(AF_INET, pdns_addr, &dns_addr,
-                                  sizeof(dns_addr), NULL, NULL, &dns_addr_time);
+                                  sizeof(dns_addr),
+                                  pdns_port, &dns_port,
+                                  NULL, NULL, &dns_addr_time);
 }
 
-int get_dns6_addr(struct in6_addr *pdns6_addr, uint32_t *scope_id)
+int get_dns6_addr(struct in6_addr *pdns6_addr, uint16_t *pdns6_port,
+                  uint32_t *scope_id)
 {
     if (!in6_zero(&dns6_addr)) {
         int ret;
         ret = get_dns_addr_cached(pdns6_addr, &dns6_addr, sizeof(dns6_addr),
-                                  &dns6_addr_time);
+                                  pdns6_port, dns6_port, &dns6_addr_time);
         if (ret == 0) {
             *scope_id = dns6_scope_id;
         }
@@ -362,6 +379,7 @@ int get_dns6_addr(struct in6_addr *pdns6_addr, uint32_t *scope_id)
     }
     return get_dns_addr_libresolv(AF_INET6, pdns6_addr, &dns6_addr,
                                   sizeof(dns6_addr),
+                                  pdns6_port, &dns6_port,
                                   scope_id, &dns6_scope_id, &dns6_addr_time);
 }
 
@@ -440,6 +458,7 @@ static bool try_and_setdns_server(int af, unsigned found, unsigned if_index,
 
 static int get_dns_addr_resolv_conf(int af, void *pdns_addr, void *cached_addr,
                                     socklen_t addrlen,
+                                    uint16_t *pdns_port, uint16_t *cached_port,
                                     uint32_t *scope_id, uint32_t *cached_scope_id,
                                     unsigned *cached_time)
 {
@@ -488,10 +507,13 @@ static int get_dns_addr_resolv_conf(int af, void *pdns_addr, void *cached_addr,
 			cached_scope_id, cached_time);
     }
 
+    if (found)
+        *pdns_port = *cached_port = htons(53); // TODO: honor custom port
+
     return found ? 0 : -1;
 }
 
-int get_dns_addr(struct in_addr *pdns_addr)
+int get_dns_addr(struct in_addr *pdns_addr, uint16_t *pdns_port)
 {
     static struct stat dns_addr_stat;
 
@@ -505,10 +527,12 @@ int get_dns_addr(struct in_addr *pdns_addr)
     }
     return get_dns_addr_resolv_conf(AF_INET, pdns_addr, &dns_addr,
                                     sizeof(dns_addr),
+                                    pdns_port, &dns_port,
                                     NULL, NULL, &dns_addr_time);
 }
 
-int get_dns6_addr(struct in6_addr *pdns6_addr, uint32_t *scope_id)
+int get_dns6_addr(struct in6_addr *pdns6_addr, uint16_t *pdns6_port,
+                  uint32_t *scope_id)
 {
     static struct stat dns6_addr_stat;
 
@@ -525,6 +549,7 @@ int get_dns6_addr(struct in6_addr *pdns6_addr, uint32_t *scope_id)
     }
     return get_dns_addr_resolv_conf(AF_INET6, pdns6_addr, &dns6_addr,
                                     sizeof(dns6_addr),
+                                    pdns6_port, &dns6_port,
                                     scope_id, &dns6_scope_id, &dns6_addr_time);
 }
 
diff --git a/src/slirp.h b/src/slirp.h
index b4f46c8..6333031 100644
--- a/src/slirp.h
+++ b/src/slirp.h
@@ -231,11 +231,12 @@ struct Slirp {
  */
 void if_start(Slirp *);
 
-/* Get the address of the DNS server on the host side */
-int get_dns_addr(struct in_addr *pdns_addr);
+/* Get the IPv4 address and port of the DNS server on the host side */
+int get_dns_addr(struct in_addr *pdns_addr, uint16_t *pdns_port);
 
-/* Get the IPv6 address of the DNS server on the host side */
-int get_dns6_addr(struct in6_addr *pdns6_addr, uint32_t *scope_id);
+/* Get the IPv6 address and port of the DNS server on the host side */
+int get_dns6_addr(struct in6_addr *pdns6_addr, uint16_t *pdns_port,
+                  uint32_t *scope_id);
 
 /* ncsi.c */
 
diff --git a/src/socket.c b/src/socket.c
index 278bf27..b2f8587 100644
--- a/src/socket.c
+++ b/src/socket.c
@@ -968,7 +968,8 @@ void sofwdrain(struct socket *so)
 static bool sotranslate_out4(Slirp *s, struct socket *so, struct sockaddr_in *sin)
 {
     if (!s->disable_dns && so->so_faddr.s_addr == s->vnameserver_addr.s_addr) {
-        return so->so_fport == htons(53) && get_dns_addr(&sin->sin_addr) >= 0;
+        return (so->so_fport == htons(53) &&
+                get_dns_addr(&sin->sin_addr, &sin->sin_port) >= 0);
     }
 
     if (so->so_faddr.s_addr == s->vhost_addr.s_addr ||
@@ -987,7 +988,8 @@ static bool sotranslate_out6(Slirp *s, struct socket *so, struct sockaddr_in6 *s
 {
     if (!s->disable_dns && in6_equal(&so->so_faddr6, &s->vnameserver_addr6)) {
         uint32_t scope_id;
-        if (so->so_fport == htons(53) && get_dns6_addr(&sin->sin6_addr, &scope_id) >= 0) {
+        if (so->so_fport == htons(53) &&
+                get_dns6_addr(&sin->sin6_addr, &sin->sin6_port, &scope_id) >= 0) {
             sin->sin6_scope_id = scope_id;
             return true;
         }
@@ -1034,6 +1036,8 @@ void sotranslate_in(struct socket *so, struct sockaddr_storage *addr)
     struct sockaddr_in *sin = (struct sockaddr_in *)addr;
     struct sockaddr_in6 *sin6 = (struct sockaddr_in6 *)addr;
 
+    uint16_t dns_port;
+
     switch (addr->ss_family) {
     case AF_INET:
         if ((so->so_faddr.s_addr & slirp->vnetwork_mask.s_addr) ==
@@ -1047,6 +1051,13 @@ void sotranslate_in(struct socket *so, struct sockaddr_storage *addr)
                 sin->sin_addr = so->so_faddr;
             }
         }
+
+        struct in_addr sin_addr;
+        if (get_dns_addr(&sin_addr, &dns_port) >= 0 &&
+                sin->sin_port == dns_port &&
+                sin->sin_addr.s_addr == sin_addr.s_addr)
+            sin->sin_port = htons(53);
+
         break;
 
     case AF_INET6:
@@ -1057,6 +1068,15 @@ void sotranslate_in(struct socket *so, struct sockaddr_storage *addr)
                 sin6->sin6_addr = so->so_faddr6;
             }
         }
+
+        struct in6_addr sin6_addr;
+        uint32_t scope_id;
+        if (get_dns6_addr(&sin6_addr, &dns_port, &scope_id) >= 0 &&
+                sin6->sin6_port == dns_port &&
+                sin6->sin6_scope_id == scope_id &&
+                in6_equal(&sin6->sin6_addr, &sin6_addr))
+            sin6->sin6_port = htons(53);
+
         break;
 
     default:
diff --git a/src/udp.c b/src/udp.c
index eb20bbb..14704e5 100644
--- a/src/udp.c
+++ b/src/udp.c
@@ -263,6 +263,8 @@ int udp_output(struct socket *so, struct mbuf *m, const struct sockaddr_in *sadd
     DEBUG_ARG("m = %p", m);
     DEBUG_ARG("saddr = %s", inet_ntop(AF_INET, &saddr->sin_addr, addr, sizeof(addr)));
     DEBUG_ARG("daddr = %s", inet_ntop(AF_INET, &daddr->sin_addr, addr, sizeof(addr)));
+    DEBUG_ARG("s_inport = %d", ntohs(saddr->sin_port));
+    DEBUG_ARG("d_inport = %d", ntohs(daddr->sin_port));
 
     /*
      * Adjust for header