implement IP_RECVTTL socket option.

when set on raw or udp sockets, userland receives the incoming packet's TTL
as ancillary data (cmsg shitz). modeled after the FreeBSD implementation.
ok claudio djm deraadt

4 files changed, 22 insertions, 5 deletions

diff --git a/sys/netinet/in.h b/sys/netinet/in.h
index eb27cf0b2cb..22923c5352c 100644
--- a/sys/netinet/in.h
+++ b/sys/netinet/in.h
@@ -1,4 +1,4 @@
-/*	$OpenBSD: in.h,v 1.71 2006/06/18 11:47:45 pascoe Exp $	*/
+/*	$OpenBSD: in.h,v 1.72 2006/10/11 09:29:20 henning Exp $	*/
 /*	$NetBSD: in.h,v 1.20 1996/02/13 23:41:47 christos Exp $	*/
 
 /*
@@ -265,6 +265,7 @@ struct ip_opts {
 #define IP_IPSEC_REMOTE_AUTH	28   /* buf; IPsec remote auth material */
 #define IP_IPCOMP_LEVEL		29   /* int; compression used */
 #define IP_RECVIF		30   /* bool; receive reception if w/dgram */
+#define IP_RECVTTL		31   /* bool; receive IP TTL w/dgram */
 
 /*
  * Security levels - IPsec, not IPSO
diff --git a/sys/netinet/in_pcb.h b/sys/netinet/in_pcb.h
index a6a0d22e021..28614c186c7 100644
--- a/sys/netinet/in_pcb.h
+++ b/sys/netinet/in_pcb.h
@@ -1,4 +1,4 @@
-/*	$OpenBSD: in_pcb.h,v 1.55 2006/09/26 21:10:53 deraadt Exp $	*/
+/*	$OpenBSD: in_pcb.h,v 1.56 2006/10/11 09:29:20 henning Exp $	*/
 /*	$NetBSD: in_pcb.h,v 1.14 1996/02/13 23:42:00 christos Exp $	*/
 
 /*
@@ -168,9 +168,10 @@ struct inpcbtable {
 #define	INP_HIGHPORT	0x010	/* user wants "high" port binding */
 #define	INP_LOWPORT	0x020	/* user wants "low" port binding */
 #define	INP_RECVIF	0x080	/* receive incoming interface */
+#define	INP_RECVTTL	0x040	/* receive incoming IP TTL */
 
 #define	INP_CONTROLOPTS	(INP_RECVOPTS|INP_RECVRETOPTS|INP_RECVDSTADDR| \
-	    INP_RXSRCRT|INP_HOPLIMIT|INP_RECVIF)
+	    INP_RXSRCRT|INP_HOPLIMIT|INP_RECVIF|INP_RECVTTL)
 
 /*
  * These flags' values should be determined by either the transport
diff --git a/sys/netinet/ip_input.c b/sys/netinet/ip_input.c
index 29803454585..366fb593b16 100644
--- a/sys/netinet/ip_input.c
+++ b/sys/netinet/ip_input.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: ip_input.c,v 1.143 2006/06/18 12:03:19 pascoe Exp $	*/
+/*	$OpenBSD: ip_input.c,v 1.144 2006/10/11 09:29:20 henning Exp $	*/
 /*	$NetBSD: ip_input.c,v 1.30 1996/03/16 23:53:58 christos Exp $	*/
 
 /*
@@ -1697,5 +1697,11 @@ ip_savecontrol(struct inpcb *inp, struct mbuf **mp, struct ip *ip,
 		if (*mp)
 			mp = &(*mp)->m_next;
 	}
+	if (inp->inp_flags & INP_RECVTTL) {
+		*mp = sbcreatecontrol((caddr_t) &ip->ip_ttl,
+		    sizeof(u_char), IP_RECVTTL, IPPROTO_IP);
+		if (*mp)
+			mp = &(*mp)->m_next;
+	}
 }
 
diff --git a/sys/netinet/ip_output.c b/sys/netinet/ip_output.c
index 65e8698445f..3a42e2f72b0 100644
--- a/sys/netinet/ip_output.c
+++ b/sys/netinet/ip_output.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: ip_output.c,v 1.180 2006/06/18 11:47:45 pascoe Exp $	*/
+/*	$OpenBSD: ip_output.c,v 1.181 2006/10/11 09:29:20 henning Exp $	*/
 /*	$NetBSD: ip_output.c,v 1.28 1996/02/13 23:43:07 christos Exp $	*/
 
 /*
@@ -1048,6 +1048,7 @@ ip_ctloutput(op, so, level, optname, mp)
 		case IP_RECVRETOPTS:
 		case IP_RECVDSTADDR:
 		case IP_RECVIF:
+		case IP_RECVTTL:
 			if (m == NULL || m->m_len != sizeof(int))
 				error = EINVAL;
 			else {
@@ -1061,6 +1062,7 @@ ip_ctloutput(op, so, level, optname, mp)
 				case IP_TTL:
 					inp->inp_ip.ip_ttl = optval;
 					break;
+
 #define	OPTSET(bit) \
 	if (optval) \
 		inp->inp_flags |= bit; \
@@ -1081,6 +1083,9 @@ ip_ctloutput(op, so, level, optname, mp)
 				case IP_RECVIF:
 					OPTSET(INP_RECVIF);
 					break;
+				case IP_RECVTTL:
+					OPTSET(INP_RECVTTL);
+					break;
 				}
 			}
 			break;
@@ -1383,6 +1388,7 @@ ip_ctloutput(op, so, level, optname, mp)
 		case IP_RECVRETOPTS:
 		case IP_RECVDSTADDR:
 		case IP_RECVIF:
+		case IP_RECVTTL:
 			*mp = m = m_get(M_WAIT, MT_SOOPTS);
 			m->m_len = sizeof(int);
 			switch (optname) {
@@ -1411,6 +1417,9 @@ ip_ctloutput(op, so, level, optname, mp)
 			case IP_RECVIF:
 				optval = OPTBIT(INP_RECVIF);
 				break;
+			case IP_RECVTTL:
+				optval = OPTBIT(INP_RECVTTL);
+				break;
 			}
 			*mtod(m, int *) = optval;
 			break;