From 7c6ff2c54f531cf42e696575b730a465d9df6000 Mon Sep 17 00:00:00 2001 From: Donald Sharp Date: Sun, 31 Jan 2021 08:32:15 -0500 Subject: [PATCH] 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 --- eigrpd/eigrp_interface.c | 18 +++++++++++++++--- eigrpd/eigrp_structs.h | 2 +- 2 files changed, 16 insertions(+), 4 deletions(-) diff --git a/eigrpd/eigrp_interface.c b/eigrpd/eigrp_interface.c index 74eff958da..bb7a930e6d 100644 --- 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 cddab57dd5..0d8bb29964 100644 --- 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; -- 2.39.5