IP_RECVTTL socket option.

Reviewed by:	Stuart Cheshire <cheshire@apple.com>

4 files changed, 20 insertions, 1 deletions

diff --git a/sys/netinet/in.h b/sys/netinet/in.h
index 83eeae7..0144416 100644
--- a/sys/netinet/in.h
+++ b/sys/netinet/in.h
@@ -399,6 +399,8 @@ __END_DECLS
 #define	IP_DUMMYNET_FLUSH	62   /* flush dummynet */
 #define	IP_DUMMYNET_GET		64   /* get entire dummynet pipes */
 
+#define	IP_RECVTTL		65   /* bool; receive IP TTL w/dgram */
+
 /*
  * Defaults and limits for options
  */
diff --git a/sys/netinet/in_pcb.h b/sys/netinet/in_pcb.h
index efb7862..9893af6 100644
--- a/sys/netinet/in_pcb.h
+++ b/sys/netinet/in_pcb.h
@@ -276,6 +276,7 @@ struct inpcbinfo {		/* XXX documentation, prefixes */
 #define	INP_RECVIF		0x80	/* receive incoming interface */
 #define	INP_MTUDISC		0x100	/* user can do MTU discovery */
 #define	INP_FAITH		0x200	/* accept FAITH'ed connections */
+#define	INP_RECVTTL		0x400	/* receive incoming IP TTL */
 
 #define IN6P_IPV6_V6ONLY	0x008000 /* restrict AF_INET6 socket for v6 */
 
@@ -288,7 +289,7 @@ struct inpcbinfo {		/* XXX documentation, prefixes */
 #define IN6P_AUTOFLOWLABEL	0x800000 /* attach flowlabel automatically */
 
 #define	INP_CONTROLOPTS		(INP_RECVOPTS|INP_RECVRETOPTS|INP_RECVDSTADDR|\
-					INP_RECVIF|\
+				 INP_RECVIF|INP_RECVTTL|\
 				 IN6P_PKTINFO|IN6P_HOPLIMIT|IN6P_HOPOPTS|\
 				 IN6P_DSTOPTS|IN6P_RTHDR|IN6P_RTHDRDSTOPTS|\
 				 IN6P_AUTOFLOWLABEL)
diff --git a/sys/netinet/ip_input.c b/sys/netinet/ip_input.c
index 5cf4ff4..32f2b6d 100644
--- a/sys/netinet/ip_input.c
+++ b/sys/netinet/ip_input.c
@@ -2052,6 +2052,12 @@ ip_savecontrol(inp, mp, ip, m)
 		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;
+	}
 #ifdef notyet
 	/* XXX
 	 * Moving these out of udp_input() made them even more broken
diff --git a/sys/netinet/ip_output.c b/sys/netinet/ip_output.c
index 1a28ed7..773768c 100644
--- a/sys/netinet/ip_output.c
+++ b/sys/netinet/ip_output.c
@@ -1424,6 +1424,7 @@ ip_ctloutput(so, sopt)
 		case IP_RECVOPTS:
 		case IP_RECVRETOPTS:
 		case IP_RECVDSTADDR:
+		case IP_RECVTTL:
 		case IP_RECVIF:
 		case IP_FAITH:
 			error = sooptcopyin(sopt, &optval, sizeof optval,
@@ -1457,6 +1458,10 @@ ip_ctloutput(so, sopt)
 				OPTSET(INP_RECVDSTADDR);
 				break;
 
+			case IP_RECVTTL:
+				OPTSET(INP_RECVTTL);
+				break;
+
 			case IP_RECVIF:
 				OPTSET(INP_RECVIF);
 				break;
@@ -1553,6 +1558,7 @@ ip_ctloutput(so, sopt)
 		case IP_RECVOPTS:
 		case IP_RECVRETOPTS:
 		case IP_RECVDSTADDR:
+		case IP_RECVTTL:
 		case IP_RECVIF:
 		case IP_PORTRANGE:
 		case IP_FAITH:
@@ -1580,6 +1586,10 @@ ip_ctloutput(so, sopt)
 				optval = OPTBIT(INP_RECVDSTADDR);
 				break;
 
+			case IP_RECVTTL:
+				optval = OPTBIT(INP_RECVTTL);
+				break;
+
 			case IP_RECVIF:
 				optval = OPTBIT(INP_RECVIF);
 				break;