Fix datagram_overhead and assorted functions

This function is supposed to calculate the overhead of the protocol
header (IP/IPv6 + TCP/UDP). But at some point the index that used
to index the array proto_overhead and the associated PROTO_N went
completely out of sync. This fixed the function and related caller
to again calculate the overhead as intended.

Note that IPv6 mapped IPv4 addresses still have the wrong overhead
calculated as they treated are as IPv6 addresses (0:0:0:0:0:ffff::/96)

Signed-off-by: Arne Schwabe <arne@rfc2549.org>
Acked-by: Frank Lichtenheld <frank@lichtenheld.com>
Acked-by: Gert Doering <gert@greenie.muc.de>
Message-Id: <20220101162532.2251835-5-arne@rfc2549.org>
URL: https://www.mail-archive.com/openvpn-devel@lists.sourceforge.net/msg23504.html
Signed-off-by: Gert Doering <gert@greenie.muc.de>

diff --git a/src/openvpn/forward.c b/src/openvpn/forward.c
index a53fc7acb08781f4d5e32c56ef3c109cc8ad60b7..af041179570d4104dffa5110fde2ca3bf4cad9cf 100644 (file)
--- a/src/openvpn/forward.c
+++ b/src/openvpn/forward.c
@@ -480,10 +480,10 @@ check_fragment(struct context *c)
     struct link_socket_info *lsi = get_link_socket_info(c);
 
     /* OS MTU Hint? */
-    if (lsi->mtu_changed)
+    if (lsi->mtu_changed && lsi->lsa)
     {
         frame_adjust_path_mtu(&c->c2.frame_fragment, c->c2.link_socket->mtu,
-                              c->options.ce.proto);
+                              lsi->lsa->actual.dest.addr.sa.sa_family, lsi->proto);
         lsi->mtu_changed = false;
     }
 
@@ -1566,8 +1566,10 @@ process_outgoing_link(struct context *c)
              */
             if (c->options.shaper)
             {
-                shaper_wrote_bytes(&c->c2.shaper, BLEN(&c->c2.to_link)
-                                   + datagram_overhead(c->options.ce.proto));
+                int overhead = datagram_overhead(c->c2.to_link_addr->dest.addr.sa.sa_family,
+                                                 c->options.ce.proto);
+                shaper_wrote_bytes(&c->c2.shaper,
+                                   BLEN(&c->c2.to_link) + overhead);
             }
 
             /*

diff --git a/src/openvpn/socket.c b/src/openvpn/socket.c
index ab0f547dcbfda8b8bb3b04962e09eee213c2f28e..45541c128597c9db000e4ce5b2ae74ffd1e73c80 100644 (file)
--- a/src/openvpn/socket.c
+++ b/src/openvpn/socket.c
@@ -44,17 +44,6 @@
 
 #include "memdbg.h"
 
-const int proto_overhead[] = { /* indexed by PROTO_x */
-    0,
-    IPv4_UDP_HEADER_SIZE, /* IPv4 */
-    IPv4_TCP_HEADER_SIZE,
-    IPv4_TCP_HEADER_SIZE,
-    IPv6_UDP_HEADER_SIZE, /* IPv6 */
-    IPv6_TCP_HEADER_SIZE,
-    IPv6_TCP_HEADER_SIZE,
-    IPv6_TCP_HEADER_SIZE,
-};
-
 /*
  * Convert sockflags/getaddr_flags into getaddr_flags
  */
@@ -1660,9 +1649,10 @@ socket_frame_init(const struct frame *frame, struct link_socket *sock)
  * to us by the OS.
  */
 void
-frame_adjust_path_mtu(struct frame *frame, int pmtu, int proto)
+frame_adjust_path_mtu(struct frame *frame, int pmtu, sa_family_t af, int proto)
 {
-    frame_set_mtu_dynamic(frame, pmtu - datagram_overhead(proto), SET_MTU_UPPER_BOUND);
+    frame_set_mtu_dynamic(frame, pmtu - datagram_overhead(af, proto),
+                          SET_MTU_UPPER_BOUND);
 }
 
 static void

diff --git a/src/openvpn/socket.h b/src/openvpn/socket.h
index 4427bca4fcac6277ab69c198690401e08657cbf7..63a254853e692cb93b87e02c9fa209b3c0270211 100644 (file)
--- a/src/openvpn/socket.h
+++ b/src/openvpn/socket.h
@@ -333,7 +333,7 @@ void do_preresolve(struct context *c);
 
 void socket_adjust_frame_parameters(struct frame *frame, int proto);
 
-void frame_adjust_path_mtu(struct frame *frame, int pmtu, int proto);
+void frame_adjust_path_mtu(struct frame *frame, int pmtu, sa_family_t af, int proto);
 
 void link_socket_close(struct link_socket *sock);
 
@@ -612,18 +612,13 @@ const char *addr_family_name(int af);
 /*
  * Overhead added to packets by various protocols.
  */
-#define IPv4_UDP_HEADER_SIZE              28
-#define IPv4_TCP_HEADER_SIZE              40
-#define IPv6_UDP_HEADER_SIZE              48
-#define IPv6_TCP_HEADER_SIZE              60
-
-extern const int proto_overhead[];
-
 static inline int
-datagram_overhead(int proto)
+datagram_overhead(sa_family_t af, int proto)
 {
-    ASSERT(proto >= 0 && proto < PROTO_N);
-    return proto_overhead [proto];
+    int overhead = 0;
+    overhead += (proto == PROTO_UDP) ? 8 : 20;
+    overhead += (af == AF_INET) ? 20 : 40;
+    return overhead;
 }
 
 /*