Fix the socket option IP_ONESBCAST by giving it its own case in ip_output()

and skip over the normal IP processing.

Add a supporting function ifa_ifwithbroadaddr() to verify and validate the
supplied subnet broadcast address.

PR:		kern/99558
Tested by:	Andrey V. Elsukov <bu7cher-at-yandex.ru>
Sponsored by:	TCP/IP Optimization Fundraise 2005
MFC after:	3 days

3 files changed, 39 insertions, 2 deletions

diff --git a/sys/net/if.c b/sys/net/if.c
index 33e26cd..278b4a8 100644
--- a/sys/net/if.c
+++ b/sys/net/if.c
@@ -1006,6 +1006,33 @@ done:
 }
 
 /*
+ * Locate an interface based on the broadcast address.
+ */
+/* ARGSUSED */
+struct ifaddr *
+ifa_ifwithbroadaddr(struct sockaddr *addr)
+{
+	struct ifnet *ifp;
+	struct ifaddr *ifa;
+
+	IFNET_RLOCK();
+	TAILQ_FOREACH(ifp, &ifnet, if_link)
+		TAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link) {
+			if (ifa->ifa_addr->sa_family != addr->sa_family)
+				continue;
+			if ((ifp->if_flags & IFF_BROADCAST) &&
+			    ifa->ifa_broadaddr &&
+			    ifa->ifa_broadaddr->sa_len != 0 &&
+			    sa_equal(ifa->ifa_broadaddr, addr))
+				goto done;
+		}
+	ifa = NULL;
+done:
+	IFNET_RUNLOCK();
+	return (ifa);
+}
+
+/*
  * Locate the point to point interface with a given destination address.
  */
 /*ARGSUSED*/
diff --git a/sys/net/if_var.h b/sys/net/if_var.h
index a73d781..6d7601c 100644
--- a/sys/net/if_var.h
+++ b/sys/net/if_var.h
@@ -683,6 +683,7 @@ int	ifpromisc(struct ifnet *, int);
 struct	ifnet *ifunit(const char *);
 
 struct	ifaddr *ifa_ifwithaddr(struct sockaddr *);
+struct	ifaddr *ifa_ifwithbroadaddr(struct sockaddr *);
 struct	ifaddr *ifa_ifwithdstaddr(struct sockaddr *);
 struct	ifaddr *ifa_ifwithnet(struct sockaddr *);
 struct	ifaddr *ifa_ifwithroute(int, struct sockaddr *, struct sockaddr *);
diff --git a/sys/netinet/ip_output.c b/sys/netinet/ip_output.c
index 8efc288..79d3806 100644
--- a/sys/netinet/ip_output.c
+++ b/sys/netinet/ip_output.c
@@ -198,6 +198,17 @@ again:
 		ifp = ia->ia_ifp;
 		ip->ip_ttl = 1;
 		isbroadcast = in_broadcast(dst->sin_addr, ifp);
+	} else if (flags & IP_SENDONES) {
+		if ((ia = ifatoia(ifa_ifwithbroadaddr(sintosa(dst)))) == NULL) {
+			ipstat.ips_noroute++;
+			error = ENETUNREACH;
+			goto bad;
+		}
+		ifp = ia->ia_ifp;
+		ip->ip_dst.s_addr = INADDR_BROADCAST;
+		dst->sin_addr = ip->ip_dst;
+		ip->ip_ttl = 1;
+		isbroadcast = 1;
 	} else if (IN_MULTICAST(ntohl(ip->ip_dst.s_addr)) &&
 	    imo != NULL && imo->imo_multicast_ifp != NULL) {
 		/*
@@ -381,8 +392,6 @@ again:
 			error = EMSGSIZE;
 			goto bad;
 		}
-		if (flags & IP_SENDONES)
-			ip->ip_dst.s_addr = INADDR_BROADCAST;
 		m->m_flags |= M_BCAST;
 	} else {
 		m->m_flags &= ~M_BCAST;