From 174b6ebd421326a0f690390b4e626d98dd205e9d Mon Sep 17 00:00:00 2001
From: Konrad Rosenbaum <konrad@silmor.de>
Date: Sat, 13 Feb 2010 18:26:40 +0000
Subject: [PATCH] regularly scan for lost interface

git-svn-id: https://silmor.de/svn/misc/tdhcp@176 752dcaaa-03e5-0310-b894-97e397d490cd
---
 server.c |   13 ++++++++++---
 sock.c   |   14 ++++++++++++++
 sock.h   |    3 +++
 3 files changed, 27 insertions(+), 3 deletions(-)

diff --git a/server.c b/server.c
index 04374be..0e72a9b 100644
--- a/server.c
+++ b/server.c
@@ -391,17 +391,19 @@ int main(int argc,char**argv)
 	while(1){
 		fd_set rfd,xfd;
 		int sret;
+		struct timeval tv;
 		//wait for event
 		FD_ZERO(&rfd);
 		FD_ZERO(&xfd);
 		FD_SET(sockfd,&rfd);
 		FD_SET(sockfd,&xfd);
-		sret=select(sockfd+1,&rfd,0,&xfd,0);
+		tv.tv_sec=1;tv.tv_usec=0;
+		sret=select(sockfd+1,&rfd,0,&xfd,&tv);
 		//check for errors
 		if(sret<0){
 			int e=errno;
 			if(e==EAGAIN)continue;
-			td_log(LOGERROR,"Error caught: %s\n",strerror(e));
+			td_log(LOGERROR,"Error caught: %s",strerror(e));
 			return 1;
 		}
 		//check for event
@@ -413,10 +415,15 @@ int main(int argc,char**argv)
 					handlemessage(msg2);
 			}
 			if(FD_ISSET(sockfd,&xfd)){
-				td_log(LOGERROR,"Exception on socket caught.\n");
+				td_log(LOGERROR,"Exception on socket caught.");
 				return 1;
 			}
 		}
+		//check that the interface still exists
+		if(!checkiface()){
+			td_log(LOGERROR,"Interface lost, exiting.");
+			return 1;
+		}
 	}
 	/*should not be reachable*/
 	td_log(LOGDEBUG,"hmm, Konrad needs better coffee - this line should not be reachable");
diff --git a/sock.c b/sock.c
index 6c5ac52..a1b204d 100644
--- a/sock.c
+++ b/sock.c
@@ -58,6 +58,20 @@ static void get_if_lladdr(const char*dev,struct sockaddr_in6*sa)
 	freeifaddrs(ifa);
 }
 
+int checkiface()
+{
+	struct ifreq ifr;
+	//sanity check
+	if(ifindex<0 || sockfd<0)return 0;
+	//try to find the iface
+	Memzero(&ifr,sizeof(ifr));
+	ifr.ifr_ifindex=ifindex;
+	if(ioctl(sockfd,SIOCGIFNAME,&ifr)<0){
+		return 0;
+	}
+	return 1;
+}
+
 /*initializes the socket on port*/
 void initsocket(short port,const char*dev)
 {
diff --git a/sock.h b/sock.h
index fad3663..d30a6b4 100644
--- a/sock.h
+++ b/sock.h
@@ -25,6 +25,9 @@ void initsocket(short,const char*);
 /*joins DHCP multicast group*/
 void joindhcp();
 
+/*checks that the interface still exists; returns true if found*/
+int checkiface();
+
 /*set the server multicast as target*/
 struct sockaddr_in6;
 void settargetserver(struct sockaddr_in6*);
-- 
1.7.2.5