Babel: Implement IPv6 prefix compression on outgoing updates (b3c6273e) · Commits · 戴 / Bird

proto/babel/packets.c

+33 −1

Original line number	Diff line number	Diff line
		@@ -133,6 +133,8 @@ struct babel_write_state {
		u8 router_id_seen;
		ip_addr next_hop_ip4;
		ip_addr next_hop_ip6;
		u8 def_ip6_prefix[16]; /* Implicit IPv6 prefix in network order */
		u8 def_ip6_pxlen;
		};


		@@ -150,6 +152,14 @@ struct babel_write_state {

		#define NET_SIZE(n) BYTES(net_pxlen(n))

		static inline uint
		bytes_equal(u8 b1, u8 b2, uint maxlen)
		{
		uint i;
		for (i = 0; (i < maxlen) && (b1 == b2); i++, b1++, b2++)
		;
		return i;
		}

		static inline u16
		get_time16(const void *p)
		@@ -696,7 +706,29 @@ babel_write_update(struct babel_tlv hdr, union babel_msg m,
		{
		tlv->ae = BABEL_AE_IP6;
		tlv->plen = net6_pxlen(&msg->net);

		/* Address compression - omit initial matching bytes */
		u8 buf[16], omit;
		put_ip6(buf, net6_prefix(&msg->net));
		omit = bytes_equal(buf, state->def_ip6_prefix,
		MIN(tlv->plen, state->def_ip6_pxlen) / 8);

		if (omit > 0)
		{
		memcpy(tlv->addr, buf + omit, NET_SIZE(&msg->net) - omit);

		tlv->omitted = omit;
		tlv->length -= omit;
		len -= omit;
		}
		else
		{
		put_ip6_px(tlv->addr, &msg->net);
		tlv->flags \|= BABEL_FLAG_DEF_PREFIX;

		put_ip6(state->def_ip6_prefix, net6_prefix(&msg->net));
		state->def_ip6_pxlen = tlv->plen;
		}
		}

		put_time16(&tlv->interval, msg->interval);