eigrpd: Correctly set the mtu for eigrp packets sent

This version of eigrp pre-calculated the eigrp metric
to be a default of 1500 bytes, but unfortunately it
had entered the byte order wrong.

Modify the code to properly set the byte order
according to the eigrp rfc as well as actually
read in and transmit the mtu of the interface
instead of hard coding it to 1500 bytes.

Fixes: #7986
Signed-off-by: Donald Sharp <sharpd@nvidia.com>

diff --git a/eigrpd/eigrp_interface.c b/eigrpd/eigrp_interface.c
index 74eff958da6b7591d822bd1e143095bf227a1f5d..bb7a930e6d928055565a756c132b653cf309d354 100644 (file)
--- a/eigrpd/eigrp_interface.c
+++ b/eigrpd/eigrp_interface.c
@@ -229,6 +229,20 @@ void eigrp_del_if_params(struct eigrp_if_params *eip)
                free(eip->auth_keychain);
 }
 
+/*
+ * Set the network byte order of the 3 bytes we send
+ * of the mtu of the link.
+ */
+static void eigrp_mtu_convert(struct eigrp_metrics *metric, uint32_t host_mtu)
+{
+       uint32_t network_mtu = htonl(host_mtu);
+       uint8_t *nm = (uint8_t *)&network_mtu;
+
+       metric->mtu[0] = nm[1];
+       metric->mtu[1] = nm[2];
+       metric->mtu[2] = nm[3];
+}
+
 int eigrp_if_up(struct eigrp_interface *ei)
 {
        struct eigrp_prefix_descriptor *pe;
@@ -256,9 +270,7 @@ int eigrp_if_up(struct eigrp_interface *ei)
        metric.delay = eigrp_delay_to_scaled(ei->params.delay);
        metric.load = ei->params.load;
        metric.reliability = ei->params.reliability;
-       metric.mtu[0] = 0xDC;
-       metric.mtu[1] = 0x05;
-       metric.mtu[2] = 0x00;
+       eigrp_mtu_convert(&metric, ei->ifp->mtu);
        metric.hop_count = 0;
        metric.flags = 0;
        metric.tag = 0;

diff --git a/eigrpd/eigrp_structs.h b/eigrpd/eigrp_structs.h
index cddab57dd54ee4c35f8209ffe66bf417d3a92d4b..0d8bb2996416ed0efb651960dfcd2b6a4e59b9f2 100644 (file)
--- a/eigrpd/eigrp_structs.h
+++ b/eigrpd/eigrp_structs.h
@@ -40,7 +40,7 @@
 struct eigrp_metrics {
        uint32_t delay;
        uint32_t bandwidth;
-       unsigned char mtu[3];
+       uint8_t mtu[3];
        uint8_t hop_count;
        uint8_t reliability;
        uint8_t load;