Don't try to set MTU on tunnel interface within (lib)openconnect itself

This has been the responsibility of the vpnc-script for a very long time,
but the MTU-setting code was retained in openconnect for compatibility with
ancient versions of the vpnc-script.  The MTU-setting code causes noisy
errors when running OpenConnect as non-root, and is simply redundant with
all vpnc-scripts since at least 2009 (see
https://gitlab.com/openconnect/vpnc-scripts/commit/02b674554db6cf662283ed74941564ccb9c5a8a4).

We will need to refine the MTU-setting code in the future (see
https://gitlab.com/openconnect/openconnect/-/issues/244#note_576191228), but
for now we should remove this code.

Signed-off-by: Daniel Lenski <dlenski@gmail.com>

diff --git a/tun.c b/tun.c
index f5aafc589bd95f481ed72a7b66565dd69bb9f92a..a50485d6eeb41e55c539bcdf535a194c7c4ffd89 100644 (file)
--- a/tun.c
+++ b/tun.c
@@ -186,7 +186,6 @@ intptr_t os_setup_tun(struct openconnect_info *vpninfo)
 
 #else /* !__sun__ && !__native_client__ */
 
-/* MTU setting code for both Linux and BSD systems */
 static void ifreq_set_ifname(struct openconnect_info *vpninfo, struct ifreq *ifr)
 {
        char *ifname = openconnect_utf8_to_legacy(vpninfo, vpninfo->ifname);
@@ -195,28 +194,6 @@ static void ifreq_set_ifname(struct openconnect_info *vpninfo, struct ifreq *ifr
                free(ifname);
 }
 
-static int set_tun_mtu(struct openconnect_info *vpninfo)
-{
-       struct ifreq ifr;
-       int net_fd;
-
-       net_fd = socket(PF_INET, SOCK_DGRAM, 0);
-       if (net_fd < 0) {
-               vpn_perror(vpninfo, _("open net"));
-               return -EINVAL;
-       }
-
-       memset(&ifr, 0, sizeof(ifr));
-       ifreq_set_ifname(vpninfo, &ifr);
-       ifr.ifr_mtu = vpninfo->ip_info.mtu;
-
-       if (ioctl(net_fd, SIOCSIFMTU, &ifr) < 0)
-               vpn_perror(vpninfo, _("SIOCSIFMTU"));
-
-       close(net_fd);
-       return 0;
-}
-
 #ifdef IFF_TUN /* Linux */
 intptr_t os_setup_tun(struct openconnect_info *vpninfo)
 {
@@ -263,9 +240,6 @@ intptr_t os_setup_tun(struct openconnect_info *vpninfo)
        if (!vpninfo->ifname)
                vpninfo->ifname = strdup(ifr.ifr_name);
 
-       /* Ancient vpnc-scripts might not get this right */
-       set_tun_mtu(vpninfo);
-
        return tun_fd;
 }
 #else /* BSD et al, including OS X */
@@ -440,9 +414,6 @@ intptr_t os_setup_tun(struct openconnect_info *vpninfo)
        }
 #endif
 
-       /* Ancient vpnc-scripts might not get this right */
-       set_tun_mtu(vpninfo);
-
        return tun_fd;
 }
 #endif /* !IFF_TUN (i.e. BSD) */