netlink: Plumb "sender" through to ICMP generation

In order for a point-to-point netlink to correctly construct and
deliver ICMP, it needs to know which way the original packet was
going.  So provide the ICMP generation code with this information, in
the form of the "sender" client.

No functional change.

Signed-off-by: Ian Jackson <ijackson@chiark.greenend.org.uk>

diff --git a/netlink.c b/netlink.c
index e53c339..b14d2eb 100644 (file)
--- a/netlink.c
+++ b/netlink.c
@@ -381,7 +381,9 @@ static uint16_t netlink_icmp_reply_len(struct buffer_if *buf)
 
 /* client indicates where the packet we're constructing a response to
    comes from. NULL indicates the host. */
-static void netlink_icmp_simple(struct netlink *st, struct buffer_if *buf,
+static void netlink_icmp_simple(struct netlink *st,
+                               struct netlink_client *origsender,
+                               struct buffer_if *buf,
                                uint8_t type, uint8_t code,
                                union icmpinfofield info)
 {
@@ -470,6 +472,7 @@ static const char *fragment_filter_header(uint8_t *base, long *hlp)
 
 /* Fragment or send ICMP Fragmentation Needed */
 static void netlink_maybe_fragment(struct netlink *st,
+                                  struct netlink_client *sender,
                                   netlink_deliver_fn *deliver,
                                   void *deliver_dst,
                                   const char *delivery_name,
@@ -501,7 +504,7 @@ static void netlink_maybe_fragment(struct netlink *st,
     if (orig_frag&IPHDR_FRAG_DONT) {
        union icmpinfofield info =
            { .fragneeded = { .unused = 0, .mtu = htons(mtu) } };
-       netlink_icmp_simple(st,buf,
+       netlink_icmp_simple(st,sender,buf,
                            ICMP_TYPE_UNREACHABLE,
                            ICMP_CODE_FRAGMENTATION_REQUIRED,
                            info);
@@ -596,7 +599,7 @@ static void netlink_client_deliver(struct netlink *st,
        BUF_FREE(buf);
        return;
     }
-    netlink_maybe_fragment(st, client->deliver,client->dst,client->name,
+    netlink_maybe_fragment(st,NULL, client->deliver,client->dst,client->name,
                           client->mtu, source,dest,buf);
     client->outcount++;
 }
@@ -604,10 +607,11 @@ static void netlink_client_deliver(struct netlink *st,
 /* Deliver a packet to the host; used after we have decided that that
  * is what to do with it. */
 static void netlink_host_deliver(struct netlink *st,
+                                struct netlink_client *sender,
                                 uint32_t source, uint32_t dest,
                                 struct buffer_if *buf)
 {
-    netlink_maybe_fragment(st, st->deliver_to_host,st->dst,"(host)",
+    netlink_maybe_fragment(st,sender, st->deliver_to_host,st->dst,"(host)",
                           st->mtu, source,dest,buf);
     st->outcount++;
 }
@@ -690,7 +694,7 @@ static void netlink_packet_deliver(struct netlink *st,
        /* The packet's not going down a tunnel.  It might (ought to)
           be for the host.   */
        if (ipset_contains_addr(st->networks,dest)) {
-           netlink_host_deliver(st,source,dest,buf);
+           netlink_host_deliver(st,sender,source,dest,buf);
            BUF_ASSERT_FREE(buf);
        } else {
            string_t s,d;
@@ -699,7 +703,7 @@ static void netlink_packet_deliver(struct netlink *st,
            Message(M_DEBUG,"%s: don't know where to deliver packet "
                    "(s=%s, d=%s)\n", st->name, s, d);
            free(s); free(d);
-           netlink_icmp_simple(st,buf,ICMP_TYPE_UNREACHABLE,
+           netlink_icmp_simple(st,sender,buf,ICMP_TYPE_UNREACHABLE,
                                ICMP_CODE_NET_UNREACHABLE, icmp_noinfo);
            BUF_FREE(buf);
        }
@@ -716,7 +720,7 @@ static void netlink_packet_deliver(struct netlink *st,
                    st->name,s,d);
            free(s); free(d);
                    
-           netlink_icmp_simple(st,buf,ICMP_TYPE_UNREACHABLE,
+           netlink_icmp_simple(st,sender,buf,ICMP_TYPE_UNREACHABLE,
                                ICMP_CODE_NET_PROHIBITED, icmp_noinfo);
            BUF_FREE(buf);
        } else {
@@ -726,7 +730,7 @@ static void netlink_packet_deliver(struct netlink *st,
                BUF_ASSERT_FREE(buf);
            } else {
                /* Generate ICMP destination unreachable */
-               netlink_icmp_simple(st,buf,
+               netlink_icmp_simple(st,sender,buf,
                                    ICMP_TYPE_UNREACHABLE,
                                    ICMP_CODE_NET_UNREACHABLE,
                                    icmp_noinfo);
@@ -749,7 +753,7 @@ static void netlink_packet_forward(struct netlink *st,
     /* Packet has already been checked */
     if (iph->ttl<=1) {
        /* Generate ICMP time exceeded */
-       netlink_icmp_simple(st,buf,ICMP_TYPE_TIME_EXCEEDED,
+       netlink_icmp_simple(st,sender,buf,ICMP_TYPE_TIME_EXCEEDED,
                            ICMP_CODE_TTL_EXCEEDED,icmp_noinfo);
        BUF_FREE(buf);
        return;
@@ -807,7 +811,7 @@ static void netlink_packet_local(struct netlink *st,
        Message(M_WARNING,"%s: unknown incoming ICMP\n",st->name);
     } else {
        /* Send ICMP protocol unreachable */
-       netlink_icmp_simple(st,buf,ICMP_TYPE_UNREACHABLE,
+       netlink_icmp_simple(st,sender,buf,ICMP_TYPE_UNREACHABLE,
                            ICMP_CODE_PROTOCOL_UNREACHABLE,icmp_noinfo);
        BUF_FREE(buf);
        return;
@@ -880,7 +884,7 @@ static void netlink_incoming(struct netlink *st, struct netlink_client *sender,
        address validity and generate ICMP, etc. */
     if (st->ptp) {
        if (sender) {
-           netlink_host_deliver(st,source,dest,buf);
+           netlink_host_deliver(st,sender,source,dest,buf);
        } else {
            netlink_client_deliver(st,st->clients,source,dest,buf);
        }