Author: eugen
Date: Wed Jul 11 09:41:50 2018
New Revision: 336195
URL: https://svnweb.freebsd.org/changeset/base/336195
Log:
Make dhclient(8) verify if new MTU (option 26) differs from current one and
skip unneeded MTU change.
This check eliminates infinite loop of MTU change / link flap / lease
verification / MTU change / link flap etc.
in case of some NIC drivers like em(4) or igb(4).
N.B.: obsolete u_int16_t is used in consistency with the rest of the file.
PR: 229432
Approved by: mav (mentor)
MFC after: 1 week
Modified:
head/sbin/dhclient/dispatch.c
Modified: head/sbin/dhclient/dispatch.c
==============================================================================
--- head/sbin/dhclient/dispatch.c Wed Jul 11 07:45:04 2018
(r336194)
+++ head/sbin/dhclient/dispatch.c Wed Jul 11 09:41:50 2018
(r336195)
@@ -547,17 +547,29 @@ interface_set_mtu_priv(char *ifname, u_int16_t mtu)
{
struct ifreq ifr;
int sock;
+ u_int16_t old_mtu;
if ((sock = socket(AF_INET, SOCK_DGRAM, 0)) == -1)
error("Can't create socket");
memset(&ifr, 0, sizeof(ifr));
+ old_mtu = 0;
strlcpy(ifr.ifr_name, ifname, sizeof(ifr.ifr_name));
- ifr.ifr_mtu = mtu;
- if (ioctl(sock, SIOCSIFMTU, &ifr) == -1)
- warning("SIOCSIFMTU failed (%d): %s", mtu,
+ if (ioctl(sock, SIOCGIFMTU, (caddr_t)&ifr) == -1)
+ warning("SIOCGIFMTU failed (%s): %s", ifname,
strerror(errno));
+ else
+ old_mtu = ifr.ifr_mtu;
+
+ if (mtu != old_mtu) {
+ ifr.ifr_mtu = mtu;
+
+ if (ioctl(sock, SIOCSIFMTU, &ifr) == -1)
+ warning("SIOCSIFMTU failed (%d): %s", mtu,
+ strerror(errno));
+ }
+
close(sock);
}
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