Date: Wed, 11 Jul 2018 09:41:50 +0000 (UTC) From: Eugene Grosbein <eugen@FreeBSD.org> To: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org Subject: svn commit: r336195 - head/sbin/dhclient Message-ID: <201807110941.w6B9fogg097391@repo.freebsd.org>
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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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