Support the 0.0.0.0 and 255.255.255.255 IPv4 addresses in the ipAddrTable.

This fixes an issue which aborted the address traversal / SNMP walk when
an "any"/0.0.0.0 address was configured on an interface.  The problem
was found with a pppoe(4) device that is typically configured with 0.0.0.0
on startup.

Found and fix tested by Gerhard Roth

3 files changed, 40 insertions, 16 deletions

diff --git a/usr.sbin/snmpd/mib.c b/usr.sbin/snmpd/mib.c
index 68ddc7c2f20..d00fb5456c4 100644
--- a/usr.sbin/snmpd/mib.c
+++ b/usr.sbin/snmpd/mib.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: mib.c,v 1.60 2012/09/20 20:11:58 yuo Exp $	*/
+/*	$OpenBSD: mib.c,v 1.61 2012/10/01 11:36:55 reyk Exp $	*/
 
 /*
  * Copyright (c) 2012 Joel Knight <joel@openbsd.org>
@@ -3139,15 +3139,22 @@ mib_ipaddrtable(struct oid *oid, struct ber_oid *o, struct ber_oid *no)
 	}
 
 	mps_decodeinaddr(no, &addr.sin_addr, OIDIDX_ipAddr + 1);
-	if (addr.sin_addr.s_addr == INADDR_ANY)
+	if (o->bo_n <= (OIDIDX_ipAddr + 1))
 		ka = kr_getaddr(NULL);
 	else
 		ka = kr_getnextaddr((struct sockaddr *)&addr);
-	if (ka == NULL || ka->addr.sa.sa_family != AF_INET)
-		addr.sin_addr.s_addr = 0;
-	else
+	if (ka == NULL || ka->addr.sa.sa_family != AF_INET) {
+		/*
+		 * Encode invalid "last address" marker which will tell
+		 * mib_ipaddr() to fail and the SNMP engine to find the
+		 * next OID.
+		 */
+		mps_encodeinaddr(no, NULL, OIDIDX_ipAddr + 1);
+	} else {
+		/* Encode real IPv4 address */
 		addr.sin_addr.s_addr = ka->addr.sin.sin_addr.s_addr;
-	mps_encodeinaddr(no, &addr.sin_addr, OIDIDX_ipAddr + 1);
+		mps_encodeinaddr(no, &addr.sin_addr, OIDIDX_ipAddr + 1);
+	}
 	smi_oidlen(o);
 
 	return (no);
@@ -3165,7 +3172,11 @@ mib_ipaddr(struct oid *oid, struct ber_oid *o, struct ber_element **elm)
 	addr.sin_family = AF_INET;
 	addr.sin_len = sizeof(addr);
 
-	mps_decodeinaddr(o, &addr.sin_addr, OIDIDX_ipAddr + 1);
+	if (mps_decodeinaddr(o, &addr.sin_addr, OIDIDX_ipAddr + 1) == -1) {
+		/* Strip invalid address and fail */
+		o->bo_n = OIDIDX_ipAddr + 1;
+		return (1);
+	}
 	ka = kr_getaddr((struct sockaddr *)&addr);
 	if (ka == NULL || ka->addr.sa.sa_family != AF_INET)
 		return (1);
diff --git a/usr.sbin/snmpd/mps.c b/usr.sbin/snmpd/mps.c
index 9f6a4129652..e913b000c5b 100644
--- a/usr.sbin/snmpd/mps.c
+++ b/usr.sbin/snmpd/mps.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: mps.c,v 1.16 2012/09/17 16:43:59 reyk Exp $	*/
+/*	$OpenBSD: mps.c,v 1.17 2012/10/01 11:36:55 reyk Exp $	*/
 
 /*
  * Copyright (c) 2007, 2008, 2012 Reyk Floeter <reyk@openbsd.org>
@@ -333,16 +333,23 @@ mps_table(struct oid *oid, struct ber_oid *o, struct ber_oid *no)
 void
 mps_encodeinaddr(struct ber_oid *o, struct in_addr *addr, int offset)
 {
-	u_int32_t	 a = htole32(addr->s_addr);
+	u_int32_t	 a, i;
 
 	o->bo_n = offset;
-	o->bo_id[o->bo_n++] = a & 0xff;
-	o->bo_id[o->bo_n++] = (a >> 8) & 0xff;
-	o->bo_id[o->bo_n++] = (a >> 16) & 0xff;
-	o->bo_id[o->bo_n++] = (a >> 24) & 0xff;
+	if (addr != NULL) {
+		a = htole32(addr->s_addr);
+		o->bo_id[o->bo_n++] = a & 0xff;
+		o->bo_id[o->bo_n++] = (a >> 8) & 0xff;
+		o->bo_id[o->bo_n++] = (a >> 16) & 0xff;
+		o->bo_id[o->bo_n++] = (a >> 24) & 0xff;
+	} else {
+		/* Create an invalid "last address" marker (5 bytes) */
+		for (i = 0; i < 5; i++)
+			o->bo_id[o->bo_n++] = 0xff;
+	}
 }
 
-void
+int
 mps_decodeinaddr(struct ber_oid *o, struct in_addr *addr, int offset)
 {
 	u_int32_t	 a;
@@ -352,4 +359,10 @@ mps_decodeinaddr(struct ber_oid *o, struct in_addr *addr, int offset)
 	    ((o->bo_id[offset + 2] & 0xff) << 16) |
 	    ((o->bo_id[offset + 3] & 0xff) << 24);
 	addr->s_addr = letoh32(a);
+
+	/* Detect invalid address */
+	if ((o->bo_n - offset) > 4)
+		return (-1);
+
+	return (0);
 }
diff --git a/usr.sbin/snmpd/snmpd.h b/usr.sbin/snmpd/snmpd.h
index 8f112433353..50c3c6efeae 100644
--- a/usr.sbin/snmpd/snmpd.h
+++ b/usr.sbin/snmpd/snmpd.h
@@ -1,4 +1,4 @@
-/*	$OpenBSD: snmpd.h,v 1.38 2012/09/18 08:29:09 reyk Exp $	*/
+/*	$OpenBSD: snmpd.h,v 1.39 2012/10/01 11:36:55 reyk Exp $	*/
 
 /*
  * Copyright (c) 2007, 2008, 2012 Reyk Floeter <reyk@openbsd.org>
@@ -495,7 +495,7 @@ int		 mps_setint(struct oid *, struct ber_oid *,
 int		 mps_getts(struct oid *, struct ber_oid *,
 		    struct ber_element **);
 void		 mps_encodeinaddr(struct ber_oid *, struct in_addr *, int);
-void		 mps_decodeinaddr(struct ber_oid *, struct in_addr *, int);
+int		 mps_decodeinaddr(struct ber_oid *, struct in_addr *, int);
 struct ber_oid	*mps_table(struct oid *, struct ber_oid *, struct ber_oid *);
 
 /* pf.c */