Description: Debug messages and invalid sockets.
 Attempt at identifying invalid socket descriptors,
 and deactivate them after detection. This should
 avoid message flooding in case of ENOTSOCK.
 .
 Implement the changes needed to make debug mode useful,
 printing to the console, and verbosely.
 .
 The verbose mode, as introduced by the Debian package
 no later than rarpd_0.981107-4, was the only way to
 initialize TMPBUF and TMPNAME in serve_it().
 Yet these two variables were used also in non-verbose
 mode to send a response notification using syslog().
 Now we always execute the code block which initializes
 both variables, but we tell syslog about an incoming
 request only in verbose mode, and we always report
 about an outgoing response packet.
Author: Mats Erik Andersson <debian@gisladisker.se>
Bug-Debian: http://bugs.debian.org/627907
Forwarded: no
Last-Update: 2013-06-20

diff -Naurp rarpd-0.981107.debian2/rarpd.8 rarpd-0.981107/rarpd.8
--- rarpd-0.981107.debian2/rarpd.8
+++ rarpd-0.981107/rarpd.8
@@ -41,7 +41,8 @@ Respond to ARP as well as RARP requests.
 Tell the user what is going on by being verbose.
 .TP
 .B \-d
-Debugging mode. Do not detach from the tty.
+Debugging mode.  Do not detach from the tty.
+This also implies verbose mode.
 .TP
 .B \-e
 Skip the check for bootable image in the TFTP boot directory. If not
diff -Naurp rarpd-0.981107.debian2/rarpd.c rarpd-0.981107/rarpd.c
--- rarpd-0.981107.debian2/rarpd.c
+++ rarpd-0.981107/rarpd.c
@@ -424,7 +424,10 @@ void arp_advise(int ifindex, u_int8_t *l
 	close(fd);
 }
 
-void serve_it(int fd)
+#define SERVEIT_KNOWN 0
+#define SERVEIT_NOTSOCK 1
+
+int serve_it(int fd)
 {
 	unsigned char buf[1024];
 	struct sockaddr_ll sll;
@@ -435,32 +438,41 @@ void serve_it(int fd)
 	int n;
 	char tmpbuf[16 * 3], tmpname[IFNAMSIZ];
 
+	if (fd < 0)
+		return SERVEIT_KNOWN;
+
 	n = recvfrom(fd, buf, sizeof(buf), MSG_DONTWAIT, (struct sockaddr*)&sll, &sll_len);
 	if (n<0) {
 		if (errno != EINTR)
 			syslog(LOG_ERR, "recvfrom: %m");
-		return;
+
+		if (errno == ENOTSOCK) {
+			syslog(LOG_ERR, "Warning: Removing a socket from list. Send HUP to renew list.");
+			return SERVEIT_NOTSOCK;
+		}
+
+		return SERVEIT_KNOWN;
 	}
 
 	/* Do not accept packets for other hosts and our own ones */
 	if (sll.sll_pkttype != PACKET_BROADCAST &&
 	    sll.sll_pkttype != PACKET_MULTICAST &&
 	    sll.sll_pkttype != PACKET_HOST)
-		return;
+		return SERVEIT_KNOWN;
 
 	if (ifidx && sll.sll_ifindex != ifidx)
-		return;
+		return SERVEIT_KNOWN;
 
 	if (n<sizeof(*a)) {
 		syslog(LOG_ERR, "truncated arp packet; len=%d", n);
-		return;
+		return SERVEIT_KNOWN;
 	}
 
 	/* Accept only RARP requests */
 	if (a->ar_op != htons(ARPOP_RREQUEST))
-		return;
+		return SERVEIT_KNOWN;
 
-	if (verbose) {
+	{
 		int i;
 		char *ptr = tmpbuf;
 		struct rarpiflink *ifl;
@@ -481,7 +493,10 @@ void serve_it(int fd)
 			tmpname[IFNAMSIZ-1] = 0;
 		} else
 			sprintf(tmpname, "if%d", sll.sll_ifindex);
-		syslog(LOG_INFO, "RARP request from %s on %s",tmpbuf,tmpname);
+
+		if (verbose)
+			syslog(LOG_INFO, "RARP request from %s on %s",
+				tmpbuf, tmpname);
 	}
 
 	/* Sanity checks */
@@ -489,12 +504,12 @@ void serve_it(int fd)
 	/* 1. IP only -> pln==4 */
 	if (a->ar_pln != 4) {
 		syslog(LOG_ERR, "interesting rarp_req plen=%d", a->ar_pln);
-		return;
+		return SERVEIT_KNOWN;
 	}
 	/* 2. ARP protocol must be IP */
 	if (a->ar_pro != htons(ETH_P_IP)) {
 		syslog(LOG_ERR, "rarp protocol is not IP %04x", ntohs(a->ar_pro));
-		return;
+		return SERVEIT_KNOWN;
 	}
 	/* 3. ARP types must match */
 	if (htons(sll.sll_hatype) != a->ar_hrd) {
@@ -505,25 +520,25 @@ void serve_it(int fd)
 				break;
 		default:
 			syslog(LOG_ERR, "rarp htype mismatch");
-			return;
+			return SERVEIT_KNOWN;
 		}
 	}
 	/* 3. LL address lengths must be equal */
 	if (a->ar_hln != sll.sll_halen) {
 		syslog(LOG_ERR, "rarp hlen mismatch");
-		return;
+		return SERVEIT_KNOWN;
 	}
 	/* 4. Check packet length */
 	if (sizeof(*a) + 2*4 + 2*a->ar_hln > n) {
 		syslog(LOG_ERR, "truncated rarp request; len=%d", n);
-		return;
+		return SERVEIT_KNOWN;
 	}
 	/* 5. Silly check: if this guy set different source
 	      addresses in MAC header and in ARP, he is insane
 	 */
 	if (memcmp(sll.sll_addr, a+1, sll.sll_halen)) {
 		syslog(LOG_ERR, "this guy set different his lladdrs in arp and header");
-		return;
+		return SERVEIT_KNOWN;
 	}
 	/* End of sanity checks */
 
@@ -531,7 +546,7 @@ void serve_it(int fd)
 	rmap = rarp_lookup(sll.sll_ifindex, sll.sll_hatype,
 			   sll.sll_halen, (unsigned char*)(a+1) + sll.sll_halen + 4);
 	if (rmap == NULL)
-		return;
+		return SERVEIT_KNOWN;
 
 	/* Prepare reply. It is almost ready, we only
 	   replace ARP packet type, put our lladdr and
@@ -541,9 +556,9 @@ void serve_it(int fd)
 	a->ar_op = htons(ARPOP_RREPLY);
 	ptr = (unsigned char*)(a+1);
 	if (put_mylladdr(&ptr, sll.sll_ifindex, rmap->lladdr_len))
-		return;
+		return SERVEIT_KNOWN;
 	if (put_myipaddr(&ptr, sll.sll_ifindex, rmap->ipaddr))
-		return;
+		return SERVEIT_KNOWN;
 	/* It is already filled */
 	ptr += rmap->lladdr_len;
 	memcpy(ptr, &rmap->ipaddr, 4);
@@ -560,6 +575,8 @@ void serve_it(int fd)
 	alarm(5);
 	sendto(fd, buf, ptr - buf, 0, (struct sockaddr*)&sll, sizeof(sll));
 	alarm(0);
+
+	return SERVEIT_KNOWN;
 }
 
 void catch_signal(int sig, void (*handler)(int))
@@ -603,6 +620,7 @@ int main(int argc, char **argv)
 
 		case 'd':
 			++debug;
+			++verbose;	/* Activate additional messages! */
 			break;
 
 		case 'v':
@@ -709,7 +727,15 @@ int main(int argc, char **argv)
 		setsid();
 	}
 
+#ifdef LOG_PERROR
+	openlog("rarpd",
+		(debug) ? (LOG_PID | LOG_CONS | LOG_PERROR)
+			: (LOG_PID | LOG_CONS),
+		LOG_DAEMON);
+#else
 	openlog("rarpd", LOG_PID | LOG_CONS, LOG_DAEMON);
+#endif /* !defined LOG_PERROR */
+
 	catch_signal(SIGALRM, sig_alarm);
 	catch_signal(SIGHUP, sig_hup);
 
@@ -736,8 +762,9 @@ int main(int argc, char **argv)
 			continue;
 		}
 		for (i=0; i<psize; i++) {
-			if (pset[i].revents&EVENTS)
-				serve_it(pset[i].fd);
+			if (pset[i].revents&EVENTS && pset[i].fd >= 0)
+				if (serve_it(pset[i].fd) == SERVEIT_NOTSOCK)
+					pset[i].fd = -1;
 		}
 	}
 }