ppp: implement per-ctrl ppp interface rename support, may be overrided by radius

 Reuse exsisting radius functionality and allow set iterface name
 template for pppoe/pptp/l2tp, '%d' specification will be replaced
 automagically to the next available index by kernel.
 PPP interface rename allows to easy differ client's interfaces from
 the other ppp ones, for example, with just netfilter interface rules.

 Example:
  [pptp]
  ifname=pptp%d will produce pptp0, pptp1, ...

1 files changed, 19 insertions, 1 deletions

diff --git a/accel-pppd/ifcfg.c b/accel-pppd/ifcfg.c
index b2cb0db..a101d47 100644
--- a/accel-pppd/ifcfg.c
+++ b/accel-pppd/ifcfg.c
@@ -321,7 +321,25 @@ int __export ap_session_rename(struct ap_session *ses, const char *ifname, int l
 			else
 				log_ppp_warn("interface rename to %s failed: %s\n", ifr.ifr_newname, strerror(errno));
 		} else {
-			log_ppp_info2("rename interface to '%s'\n", ifr.ifr_newname);
+			/* required since 2.6.27 */
+			if (strchr(ifr.ifr_newname, '%')) {
+				ifr.ifr_ifindex = ses->ifindex;
+				r = net->sock_ioctl(SIOCGIFNAME, &ifr);
+				if (r) {
+					log_ppp_error("failed to get new interface name: %s\n", strerror(errno));
+					return -1;
+				}
+				len = strnlen(ifr.ifr_name, IFNAMSIZ);
+				if (len >= IFNAMSIZ) {
+					log_ppp_error("cannot rename interface (name is too long)\n");
+					return -1;
+				}
+				ifr.ifr_name[len] = 0;
+				ifname = ifr.ifr_name;
+			} else
+				ifname = ifr.ifr_newname;
+
+			log_ppp_info2("rename interface to '%s'\n", ifname);
 			memcpy(ses->ifname, ifname, len);
 			ses->ifname[len] = 0;
 		}