BGP: Implement extended optional parameters length (524d2538) · Commits · 戴 / Bird

lib/birdlib.h

+1 −1

Original line number	Diff line number	Diff line
		@@ -38,7 +38,7 @@ struct align_probe { char x; long int y; };
		#define ARRAY_SIZE(a) (sizeof(a)/sizeof(*(a)))
		#define BYTES(n) ((((uint) (n)) + 7) / 8)
		#define CALL(fn, args...) ({ if (fn) fn(args); })
		#define ADVANCE(w, r, l) ({ r -= l; w += l; })
		#define ADVANCE(w, r, l) ({ r -= (l); w += (l); })

		static inline int uint_cmp(uint i1, uint i2)
		{ return (int)(i1 > i2) - (int)(i1 < i2); }

proto/bgp/bgp.c

+1 −0

Original line number	Diff line number	Diff line
		@@ -100,6 +100,7 @@
		* RFC 8203 - BGP Administrative Shutdown Communication
		* RFC 8212 - Default EBGP Route Propagation Behavior without Policies
		* draft-ietf-idr-bgp-extended-messages-27
		* draft-ietf-idr-ext-opt-param-07
		* draft-uttaro-idr-bgp-persistence-04
		*/

proto/bgp/packets.c

+69 −22

Original line number	Diff line number	Diff line
		@@ -294,8 +294,8 @@ bgp_write_capabilities(struct bgp_conn conn, byte buf)

		/*
		* Note that max length is ~ 22+21*af_count. With max 12 channels that is
		* 274. Option limit is 253 and buffer size is 4096, so we cannot overflow
		* unless we add new capabilities or more AFs. XXXXX
		* 274. We are limited just by buffer size (4096, minus header), as we support
		* extended optional parameres. Therefore, we have enough space for expansion.
		*/

		WALK_AF_CAPS(caps, ac)
		@@ -411,7 +411,7 @@ bgp_write_capabilities(struct bgp_conn conn, byte buf)
		return buf;
		}

		static void
		static int
		bgp_read_capabilities(struct bgp_conn conn, struct bgp_caps caps, byte *pos, int len)
		{
		struct bgp_proto *p = conn->bgp;
		@@ -577,11 +577,11 @@ bgp_read_capabilities(struct bgp_conn conn, struct bgp_caps caps, byte *pos, i
		}
		}

		return;
		return 0;

		err:
		bgp_error(conn, 2, 0, NULL, 0);
		return;
		return -1;
		}

		static int
		@@ -621,36 +621,62 @@ bgp_check_capabilities(struct bgp_conn *conn)
		}

		static int
		bgp_read_options(struct bgp_conn conn, byte pos, int len)
		bgp_read_options(struct bgp_conn conn, byte pos, uint len, uint rest)
		{
		struct bgp_proto *p = conn->bgp;
		struct bgp_caps *caps;
		int ol;
		int ext = 0;

		/* Handle extended length (draft-ietf-idr-ext-opt-param-07) */
		if ((len > 0) && (rest > 0) && (pos[0] == 255))
		{
		if (rest < 3)
		goto err;

		/* Update pos/len to describe optional data */
		len = get_u16(pos+1);
		ext = 1;
		pos += 3;
		rest -= 3;
		}

		/* Verify that optional data fits into OPEN packet */
		if (len > rest)
		goto err;

		/* Max number of announced AFIs is limited by max option length (255) */
		caps = alloca(sizeof(struct bgp_caps) + 64 * sizeof(struct bgp_af_caps));
		memset(caps, 0, sizeof(struct bgp_caps));

		/* Length of option parameter header */
		uint hlen = ext ? 3 : 2;

		while (len > 0)
		{
		if ((len < 2) \|\| (len < (2 + pos[1])))
		{ bgp_error(conn, 2, 0, NULL, 0); return -1; }
		if (len < hlen)
		goto err;

		uint otype = get_u8(pos);
		uint olen = ext ? get_u16(pos+1) : get_u8(pos+1);

		if (len < (hlen + olen))
		goto err;

		ol = pos[1];
		if (pos[0] == 2)
		if (otype == 2)
		{
		/* BGP capabilities, RFC 5492 */
		if (p->cf->capabilities)
		bgp_read_capabilities(conn, caps, pos + 2, ol);
		if (bgp_read_capabilities(conn, caps, pos + hlen, olen) < 0)
		return -1;
		}
		else
		{
		/* Unknown option */
		bgp_error(conn, 2, 4, pos, ol); /* FIXME: ol or ol+2 ? */
		bgp_error(conn, 2, 4, pos, hlen + olen);
		return -1;
		}

		ADVANCE(pos, len, 2 + ol);
		ADVANCE(pos, len, hlen + olen);
		}

		uint n = sizeof(struct bgp_caps) + caps->af_count * sizeof(struct bgp_af_caps);
		@@ -658,6 +684,10 @@ bgp_read_options(struct bgp_conn conn, byte pos, int len)
		memcpy(conn->remote_caps, caps, n);

		return 0;

		err:
		bgp_error(conn, 2, 0, NULL, 0);
		return -1;
		}

		static byte *
		@@ -676,12 +706,29 @@ bgp_create_open(struct bgp_conn conn, byte buf)
		if (p->cf->capabilities)
		{
		/* Prepare local_caps and write capabilities to buffer */
		byte *end = bgp_write_capabilities(conn, buf+12);
		uint len = end - (buf+12);
		byte *pos = buf+12;
		byte *end = bgp_write_capabilities(conn, pos);
		uint len = end - pos;

		if (len < 254)
		{
		buf[9] = len + 2; /* Optional parameters length */
		buf[10] = 2; /* Option 2: Capability list */
		buf[11] = len; /* Option data length */
		}
		else /* draft-ietf-idr-ext-opt-param-07 */
		{
		/* Move capabilities 4 B forward */
		memmove(buf + 16, pos, len);
		pos = buf + 16;
		end = pos + len;

		buf[9] = 255; /* Non-ext OP length, fake */
		buf[10] = 255; /* Non-ext OP type, signals extended length */
		put_u16(buf+11, len + 3); /* Extended optional parameters length */
		buf[13] = 2; /* Option 2: Capability list */
		put_u16(buf+14, len); /* Option extended data length */
		}

		return end;
		}
		@@ -705,8 +752,8 @@ bgp_rx_open(struct bgp_conn conn, byte pkt, uint len)
		if (conn->state != BS_OPENSENT)
		{ bgp_error(conn, 5, fsm_err_subcode[conn->state], NULL, 0); return; }

		/* Check message contents */
		if (len < 29 \|\| len != 29 + (uint) pkt[28])
		/* Check message length */
		if (len < 29)
		{ bgp_error(conn, 1, 2, pkt+16, 2); return; }

		if (pkt[19] != BGP_VERSION)
		@@ -717,7 +764,7 @@ bgp_rx_open(struct bgp_conn conn, byte pkt, uint len)
		id = get_u32(pkt+24);
		BGP_TRACE(D_PACKETS, "Got OPEN(as=%d,hold=%d,id=%R)", asn, hold, id);

		if (bgp_read_options(conn, pkt+29, pkt[28]) < 0)
		if (bgp_read_options(conn, pkt+29, pkt[28], len-29) < 0)
		return;

		if (hold > 0 && hold < 3)

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