Implement an option to administratively disable the negotiation of

IPv6 on an sppp interface.  In an IPv6-enabled kernel, every IPv6
interface automatically gets an IPv6 address assigned (and IPv6
multicast packets sent at initialization time).  For sppp links where
we know our remote peer wouldn't support IPv6 at all, there's no point
in attempting to negotiate IPV6CP (or to even dial out for an IPv6
packet at all for dial-on-demand interfaces).

I wish there were a more generic way to administratively disable IPv6
on an interface instead.  ume told me there isn't.

While i was at it, converted both, enable_vj and enable_ipv6 into flag
bits in struct sppp (enable_vj used to be an int of its own).

MFC after:	1 month

2 files changed, 60 insertions, 8 deletions

diff --git a/sys/net/if_sppp.h b/sys/net/if_sppp.h
index c4f3139..e602aa5 100644
--- a/sys/net/if_sppp.h
+++ b/sys/net/if_sppp.h
@@ -97,6 +97,13 @@ enum ppp_phase {
 struct sppp_parms {
 	enum ppp_phase pp_phase;	/* phase we're currently in */
 	int	enable_vj;		/* VJ header compression enabled */
+	int	enable_ipv6;		/*
+					 * Enable IPv6 negotiations -- only
+					 * needed since each IPv4 i/f auto-
+					 * matically gets an IPv6 address
+					 * assigned, so we can't use this as
+					 * a decision.
+					 */
 	struct slcp lcp;		/* LCP params */
 	struct sipcp ipcp;		/* IPCP params */
 	struct sipcp ipv6cp;		/* IPv6CP params */
@@ -144,7 +151,9 @@ struct sppp {
 	u_char  confid[IDX_COUNT];	/* id of last configuration request */
 	int	rst_counter[IDX_COUNT];	/* restart counter */
 	int	fail_counter[IDX_COUNT]; /* negotiation failure counter */
-	int	enable_vj;	/* VJ header compression enabled */
+	int	confflags;	/* administrative configuration flags */
+#define CONF_ENABLE_VJ    0x01	/* VJ header compression enabled */
+#define CONF_ENABLE_IPV6  0x02	/* IPv6 administratively enabled */
 	time_t	pp_last_recv;	/* time last packet has been received */
 	time_t	pp_last_sent;	/* time last packet has been sent */
 	struct callout_handle ch[IDX_COUNT]; /* per-proto and if callouts */
diff --git a/sys/net/if_spppsubr.c b/sys/net/if_spppsubr.c
index d54cfb8..600179e 100644
--- a/sys/net/if_spppsubr.c
+++ b/sys/net/if_spppsubr.c
@@ -782,12 +782,28 @@ sppp_output(struct ifnet *ifp, struct mbuf *m,
 
 	if ((ifp->if_flags & IFF_UP) == 0 ||
 	    (ifp->if_flags & (IFF_RUNNING | IFF_AUTO)) == 0) {
+#ifdef INET6
+	  drop:
+#endif
 		m_freem (m);
 		splx (s);
 		return (ENETDOWN);
 	}
 
 	if ((ifp->if_flags & (IFF_RUNNING | IFF_AUTO)) == IFF_AUTO) {
+#ifdef INET6
+		/*
+		 * XXX
+		 *
+		 * Hack to prevent the initialization-time generated
+		 * IPv6 multicast packet to erroneously cause a
+		 * dialout event in case IPv6 has been
+		 * administratively disabled on that interface.
+		 */
+		if (dst->sa_family == AF_INET6 &&
+		    !(sp->confflags & CONF_ENABLE_IPV6))
+			goto drop;
+#endif
 		/*
 		 * Interface is not yet running, but auto-dial.  Need
 		 * to start LCP for it.
@@ -1011,7 +1027,13 @@ sppp_attach(struct ifnet *ifp)
 	if(!mtx_initialized(&sp->pp_fastq.ifq_mtx))
 		mtx_init(&sp->pp_fastq.ifq_mtx, "sppp_fastq", MTX_DEF);
 	sp->pp_last_recv = sp->pp_last_sent = time_second;
-	sp->enable_vj = 1;
+	sp->confflags = 0;
+#ifdef INET
+	sp->confflags |= CONF_ENABLE_VJ;
+#endif
+#ifdef INET6
+	sp->confflags |= CONF_ENABLE_IPV6;
+#endif
 	sp->pp_comp = malloc(sizeof(struct slcompress), M_TEMP, M_WAIT);
 	sl_compress_init(sp->pp_comp, -1);
 	sppp_lcp_init(sp);
@@ -2616,7 +2638,16 @@ sppp_lcp_tlu(struct sppp *sp)
 	if (sp->pp_phase == PHASE_NETWORK) {
 		/* Notify all NCPs. */
 		for (i = 0; i < IDX_COUNT; i++)
-			if ((cps[i])->flags & CP_NCP)
+			if (((cps[i])->flags & CP_NCP) &&
+			    /*
+			     * XXX
+			     * Hack to administratively disable IPv6 if
+			     * not desired.  Perhaps we should have another
+			     * flag for this, but right now, we can make
+			     * all struct cp's read/only.
+			     */
+			    (cps[i] != &ipv6cp ||
+			     (sp->confflags & CONF_ENABLE_IPV6)))
 				(cps[i])->Open(sp);
 	}
 
@@ -2837,7 +2868,7 @@ sppp_ipcp_open(struct sppp *sp)
 		sp->ipcp.opts |= (1 << IPCP_OPT_ADDRESS);
 	} else
 		sp->ipcp.flags |= IPCP_MYADDR_SEEN;
-	if (sp->enable_vj) {
+	if (sp->confflags & CONF_ENABLE_VJ) {
 		sp->ipcp.opts |= (1 << IPCP_OPT_COMPRESSION);
 		sp->ipcp.max_state = MAX_STATES - 1;
 		sp->ipcp.compress_cid = 1;
@@ -2898,7 +2929,7 @@ sppp_ipcp_RCR(struct sppp *sp, struct lcp_header *h, int len)
 			log(-1, " %s ", sppp_ipcp_opt_name(*p));
 		switch (*p) {
 		case IPCP_OPT_COMPRESSION:
-			if (!sp->enable_vj) {
+			if (!(sp->confflags & CONF_ENABLE_VJ)) {
 				/* VJ compression administratively disabled */
 				if (debug)
 					log(-1, "[locally disabled] ");
@@ -5011,7 +5042,8 @@ sppp_params(struct sppp *sp, u_long cmd, void *data)
 		 * CHAP secrets back to userland anyway.
 		 */
 		spr->defs.pp_phase = sp->pp_phase;
-		spr->defs.enable_vj = sp->enable_vj;
+		spr->defs.enable_vj = (sp->confflags & CONF_ENABLE_VJ) != 0;
+		spr->defs.enable_ipv6 = (sp->confflags & CONF_ENABLE_IPV6) != 0;
 		spr->defs.lcp = sp->lcp;
 		spr->defs.ipcp = sp->ipcp;
 		spr->defs.ipv6cp = sp->ipv6cp;
@@ -5101,9 +5133,20 @@ sppp_params(struct sppp *sp, u_long cmd, void *data)
 		/* set LCP restart timer timeout */
 		if (spr->defs.lcp.timeout != 0)
 			sp->lcp.timeout = spr->defs.lcp.timeout * hz / 1000;
-		/* set VJ enable flag */
-		sp->enable_vj = spr->defs.enable_vj;
+		/* set VJ enable and IPv6 disable flags */
+#ifdef INET
+		if (spr->defs.enable_vj)
+			sp->confflags |= CONF_ENABLE_VJ;
+		else
+			sp->confflags &= ~CONF_ENABLE_VJ;
+#endif
+#ifdef INET6
+		if (spr->defs.enable_ipv6)
+			sp->confflags |= CONF_ENABLE_IPV6;
+		else
+			sp->confflags &= ~CONF_ENABLE_IPV6;
 		break;
+#endif
 
 	default:
 		rv = EINVAL;