Add the Babel routing protocol (RFC 6126)

This patch implements the IPv6 subset of the Babel routing protocol.
Based on the patch from Toke Hoiland-Jorgensen, with some heavy
modifications and bugfixes.

Thanks to Toke Hoiland-Jorgensen for the original patch.

configure.in

@@ -206,6 +206,9 @@ fi
 AC_SUBST(iproutedir)
 
 all_protocols="$proto_bfd bgp ospf pipe $proto_radv rip static"
+if test "$ip" = ipv6 ; then
+   all_protocols="$all_protocols babel"
+fi
 all_protocols=`echo $all_protocols | sed 's/ /,/g'`
 
 if test "$with_protocols" = all ; then

doc/bird.sgml

@@ -1380,6 +1380,102 @@ corresponding protocol sections.
 
 <chapt>Protocols
 
+<sect>Babel
+
+<sect1>Introduction
+
+<p>The Babel protocol (RFC6126) is a loop-avoiding distance-vector routing
+protocol that is robust and efficient both in ordinary wired networks and in
+wireless mesh networks. Babel is conceptually very simple in its operation and
+"just works" in its default configuration, though some configuration is possible
+and in some cases desirable.
+
+<p>While the Babel protocol is dual stack (i.e., can carry both IPv4 and IPv6
+routes over the same IPv6 transport), BIRD presently implements only the IPv6
+subset of the protocol. No Babel extensions are implemented, but the BIRD
+implementation can coexist with implementations using the extensions (and will
+just ignore extension messages).
+
+<p>The Babel protocol implementation in BIRD is currently in alpha stage.
+
+<sect1>Configuration
+
+<p>Babel supports no global configuration options apart from those common to all
+other protocols, but supports the following per-interface configuration options:
+
+<code>
+protocol babel [<name>] {
+	interface <interface pattern> {
+		type <wired|wireless>;
+		rxcost <number>;
+		hello interval <number>;
+		update interval <number>;
+		port <number>;
+		tx class|dscp <number>;
+		tx priority <number>;
+		rx buffer <number>;
+		tx length <number>;
+		check link <switch>;
+	};
+}
+</code>
+
+<descrip>
+      <tag>type wired|wireless </tag>
+      This option specifies the interface type: Wired or wireless. Wired
+      interfaces are considered more reliable, and so the default hello
+      interval is higher, and a neighbour is considered unreachable after only
+      a small number of "hello" packets are lost. On wireless interfaces,
+      hello packets are sent more often, and the ETX link quality estimation
+      technique is used to compute the metrics of routes discovered over this
+      interface. This technique will gradually degrade the metric of routes
+      when packets are lost rather than the more binary up/down mechanism of
+      wired type links. Default: <cf/wired/.
+
+      <tag>rxcost <m/num/</tag>
+      This specifies the RX cost of the interface. The route metrics will be
+      computed from this value with a mechanism determined by the interface
+      <cf/type/. Default: 96 for wired interfaces, 256 for wireless.
+
+      <tag>hello interval <m/num/</tag>
+      Interval at which periodic "hello" messages are sent on this interface,
+      in seconds. Default: 4 seconds.
+
+      <tag>update interval <m/num/</tag>
+      Interval at which periodic (full) updates are sent. Default: 4 times the
+      hello interval.
+
+      <tag>port <m/number/</tag>
+      This option selects an UDP port to operate on. The default is to operate
+      on port 6696 as specified in the Babel RFC.
+
+      <tag>tx class|dscp|priority <m/number/</tag>
+      These options specify the ToS/DiffServ/Traffic class/Priority of the
+      outgoing Babel packets. See <ref id="dsc-prio" name="tx class"> common
+      option for detailed description.
+
+      <tag>rx buffer <m/number/</tag>
+      This option specifies the size of buffers used for packet processing.
+      The buffer size should be bigger than maximal size of received packets.
+      The default value is the interface MTU, and the value will be clamped to a
+      minimum of 512 bytes + IP packet overhead.
+
+      <tag>tx length <m/number/</tag>
+      This option specifies the maximum length of generated Babel packets. To
+      avoid IP fragmentation, it should not exceed the interface MTU value.
+      The default value is the interface MTU value, and the value will be
+      clamped to a minimum of 512 bytes + IP packet overhead.
+
+      <tag>check link <m/switch/</tag>
+      If set, the hardware link state (as reported by OS) is taken into
+      consideration. When the link disappears (e.g. an ethernet cable is
+      unplugged), neighbors are immediately considered unreachable and all
+      routes received from them are withdrawn. It is possible that some
+      hardware drivers or platforms do not implement this feature. Default:
+      yes.
+</descrip>
+
+
 <sect><label id="sect-bfd">BFD
 
 <sect1>Introduction

doc/reply_codes

@@ -57,6 +57,9 @@ Reply codes of BIRD command-line interface
 1020	Show BFD sessions
 1021	Show RIP interface
 1022	Show RIP neighbors
+1023	Show Babel interfaces
+1024	Show Babel neighbors
+1025	Show Babel entries
 
 8000	Reply too long
 8001	Route not found

lib/birdlib.h

@@ -60,6 +60,7 @@
 
 #define NORET __attribute__((noreturn))
 #define UNUSED __attribute__((unused))
+#define PACKED __attribute__((packed))
 
 
 /* Microsecond time */

lib/bitops.h

@@ -25,5 +25,6 @@ u32 u32_log2(u32 v);
 
 static inline u32 u32_hash(u32 v) { return v * 2902958171u; }
 
-#endif
+static inline u8 u32_popcount(u32 v) { return __builtin_popcount(v); }
 
+#endif

lib/ip.h

@@ -26,6 +26,7 @@
 #define IP6_OSPF_ALL_ROUTERS	ipa_build6(0xFF020000, 0, 0, 5)
 #define IP6_OSPF_DES_ROUTERS	ipa_build6(0xFF020000, 0, 0, 6)
 #define IP6_RIP_ROUTERS		ipa_build6(0xFF020000, 0, 0, 9)
+#define IP6_BABEL_ROUTERS	ipa_build6(0xFF020000, 0, 0, 0x00010006)
 
 #define IP4_NONE		_MI4(0)
 #define IP6_NONE		_MI6(0,0,0,0)

lib/printf.c

@@ -124,6 +124,7 @@ static char * number(char * str, long num, int base, int size, int precision,
  * width is automatically replaced by standard IP address width which
  * depends on whether we use IPv4 or IPv6; |%#I| gives hexadecimal format),
  * |%R| for Router / Network ID (u32 value printed as IPv4 address)
+ * |%lR| for 64bit Router / Network ID (u64 value printed as eight :-separated octets)
  * and |%m| resp. |%M| for error messages (uses strerror() to translate @errno code to
  * message text). On the other hand, it doesn't support floating
  * point numbers.
@@ -137,9 +138,10 @@ int bvsnprintf(char *buf, int size, const char *fmt, va_list args)
 	unsigned long num;
 	int i, base;
 	u32 x;
+	u64 X;
 	char *str, *start;
 	const char *s;
-	char ipbuf[STD_ADDRESS_P_LENGTH+1];
+	char ipbuf[MAX(STD_ADDRESS_P_LENGTH,ROUTER_ID_64_LENGTH)+1];
 	struct iface *iface;
 
 	int flags;		/* flags to number() */
@@ -309,12 +311,27 @@ int bvsnprintf(char *buf, int size, const char *fmt, va_list args)
 
 		/* Router/Network ID - essentially IPv4 address in u32 value */
 		case 'R':
-			x = va_arg(args, u32);
-			bsprintf(ipbuf, "%d.%d.%d.%d",
-				 ((x >> 24) & 0xff),
-				 ((x >> 16) & 0xff),
-				 ((x >> 8) & 0xff),
-				 (x & 0xff));
+			if(qualifier == 'l') {
+				X = va_arg(args, u64);
+				bsprintf(ipbuf, "%02x:%02x:%02x:%02x:%02x:%02x:%02x:%02x",
+					((X >> 56) & 0xff),
+					((X >> 48) & 0xff),
+					((X >> 40) & 0xff),
+					((X >> 32) & 0xff),
+					((X >> 24) & 0xff),
+					((X >> 16) & 0xff),
+					((X >> 8) & 0xff),
+					(X & 0xff));
+			}
+			else
+			{
+				x = va_arg(args, u32);
+				bsprintf(ipbuf, "%d.%d.%d.%d",
+					((x >> 24) & 0xff),
+					((x >> 16) & 0xff),
+					((x >> 8) & 0xff),
+					(x & 0xff));
+			}
 			s = ipbuf;
 			goto str;
 

lib/string.h

@@ -30,4 +30,6 @@ static inline char *xbasename(const char *str)
   return s ? s+1 : (char *) str;
 }
 
+#define ROUTER_ID_64_LENGTH 23
+
 #endif

nest/proto.c

@@ -919,6 +919,9 @@ protos_build(void)
   proto_build(&proto_bfd);
   bfd_init_all();
 #endif
+#ifdef CONFIG_BABEL
+  proto_build(&proto_babel);
+#endif
 
   proto_pool = rp_new(&root_pool, "Protocols");
   proto_flush_event = ev_new(proto_pool);

nest/protocol.h

@@ -76,7 +76,7 @@ void protos_dump_all(void);
 
 extern struct protocol
   proto_device, proto_radv, proto_rip, proto_static,
-  proto_ospf, proto_pipe, proto_bgp, proto_bfd;
+  proto_ospf, proto_pipe, proto_bgp, proto_bfd, proto_babel;
 
 /*
  *	Routing Protocol Instance

nest/route.h

@@ -219,6 +219,12 @@ typedef struct rte {
     struct {
       u8 suppressed;			/* Used for deterministic MED comparison */
     } bgp;
+#endif
+#ifdef CONFIG_BABEL
+    struct {
+      u16 metric;			/* Babel metric */
+      u64 router_id;			/* Babel router id */
+    } babel;
 #endif
     struct {				/* Routes generated by krt sync (both temporary and inherited ones) */
       s8 src;				/* Alleged route source (see krt.h) */
@@ -374,6 +380,7 @@ typedef struct rta {
 #define RTS_OSPF_EXT2 10		/* OSPF external route type 2 */
 #define RTS_BGP 11			/* BGP route */
 #define RTS_PIPE 12			/* Inter-table wormhole */
+#define RTS_BABEL 13			/* Babel route */
 
 #define RTC_UNICAST 0
 #define RTC_BROADCAST 1
@@ -422,7 +429,8 @@ typedef struct eattr {
 #define EAP_RIP 2			/* RIP */
 #define EAP_OSPF 3			/* OSPF */
 #define EAP_KRT 4			/* Kernel route attributes */
-#define EAP_MAX 5
+#define EAP_BABEL 5			/* Babel attributes */
+#define EAP_MAX 6
 
 #define EA_CODE(proto,id) (((proto) << 8) | (id))
 #define EA_PROTO(ea) ((ea) >> 8)
@@ -547,6 +555,7 @@ extern struct protocol *attr_class_to_protocol[EAP_MAX];
 #define DEF_PREF_DIRECT	    	240	/* Directly connected */
 #define DEF_PREF_STATIC		200	/* Static route */
 #define DEF_PREF_OSPF		150	/* OSPF intra-area, inter-area and type 1 external routes */
+#define DEF_PREF_BABEL		130	/* Babel */
 #define DEF_PREF_RIP		120	/* RIP */
 #define DEF_PREF_BGP		100	/* BGP */
 #define DEF_PREF_PIPE		70	/* Routes piped from other tables */

proto/Doc

 H Protocols
+C babel
 C bfd
 C bgp
 C ospf

proto/babel/Doc

+S babel.c
+S packet.c

proto/babel/Makefile

+source=babel.c packets.c
+root-rel=../../
+dir-name=proto/babel
+
+include ../../Rules

proto/babel/babel.h

+/*
+ *	BIRD -- The Babel protocol
+ *
+ *	Copyright (c) 2015--2016 Toke Hoiland-Jorgensen
+ *
+ *	Can be freely distributed and used under the terms of the GNU GPL.
+ *
+ *	This file contains the data structures used by Babel.
+ */
+
+#ifndef _BIRD_BABEL_H_
+#define _BIRD_BABEL_H_
+
+#include "nest/bird.h"
+#include "nest/cli.h"
+#include "nest/iface.h"
+#include "nest/route.h"
+#include "nest/protocol.h"
+#include "nest/locks.h"
+#include "lib/resource.h"
+#include "lib/lists.h"
+#include "lib/socket.h"
+#include "lib/string.h"
+#include "lib/timer.h"
+
+#ifndef IPV6
+#error "The Babel protocol only speaks IPv6"
+#endif
+
+#define EA_BABEL_METRIC		EA_CODE(EAP_BABEL, 0)
+#define EA_BABEL_ROUTER_ID	EA_CODE(EAP_BABEL, 1)
+
+#define BABEL_MAGIC		42
+#define BABEL_VERSION		2
+#define BABEL_PORT		6696
+#define BABEL_INFINITY		0xFFFF
+
+
+#define BABEL_HELLO_INTERVAL_WIRED	4	/* Default hello intervals in seconds */
+#define BABEL_HELLO_INTERVAL_WIRELESS	4
+#define BABEL_UPDATE_INTERVAL_FACTOR	4
+#define BABEL_IHU_INTERVAL_FACTOR	3
+#define BABEL_IHU_EXPIRY_FACTOR(X)	((X)*3/2)	/* 1.5 */
+#define BABEL_HELLO_EXPIRY_FACTOR(X)	((X)*3/2)	/* 1.5 */
+#define BABEL_ROUTE_EXPIRY_FACTOR(X)	((X)*7/2)	/* 3.5 */
+#define BABEL_ROUTE_REFRESH_INTERVAL	2	/* Seconds before route expiry to send route request */
+#define BABEL_HOLD_TIME			10	/* Expiry time for our own routes */
+#define BABEL_RXCOST_WIRED		96
+#define BABEL_RXCOST_WIRELESS		256
+#define BABEL_INITIAL_HOP_COUNT		255
+#define BABEL_MAX_SEND_INTERVAL		5
+#define BABEL_TIME_UNITS		100	/* On-wire times are counted in centiseconds */
+
+#define BABEL_SEQNO_REQUEST_EXPIRY	60
+#define BABEL_GARBAGE_INTERVAL		300
+
+#define BABEL_OVERHEAD		(SIZE_OF_IP_HEADER+UDP_HEADER_LENGTH)
+#define BABEL_MIN_MTU		(512 + BABEL_OVERHEAD)
+
+
+enum babel_tlv_type {
+  BABEL_TLV_PAD1		= 0,
+  BABEL_TLV_PADN		= 1,
+  BABEL_TLV_ACK_REQ		= 2,
+  BABEL_TLV_ACK			= 3,
+  BABEL_TLV_HELLO		= 4,
+  BABEL_TLV_IHU 		= 5,
+  BABEL_TLV_ROUTER_ID		= 6,
+  BABEL_TLV_NEXT_HOP		= 7,
+  BABEL_TLV_UPDATE		= 8,
+  BABEL_TLV_ROUTE_REQUEST	= 9,
+  BABEL_TLV_SEQNO_REQUEST	= 10,
+  /* extensions - not implemented
+  BABEL_TLV_TS_PC		= 11,
+  BABEL_TLV_HMAC		= 12,
+  BABEL_TLV_SS_UPDATE		= 13,
+  BABEL_TLV_SS_REQUEST		= 14,
+  BABEL_TLV_SS_SEQNO_REQUEST	= 15,
+  */
+  BABEL_TLV_MAX
+};
+
+enum babel_iface_type {
+  /* In practice, UNDEF and WIRED give equivalent behaviour */
+  BABEL_IFACE_TYPE_UNDEF	= 0,
+  BABEL_IFACE_TYPE_WIRED	= 1,
+  BABEL_IFACE_TYPE_WIRELESS	= 2,
+  BABEL_IFACE_TYPE_MAX
+};
+
+enum babel_ae_type {
+  BABEL_AE_WILDCARD		= 0,
+  BABEL_AE_IP4			= 1,
+  BABEL_AE_IP6			= 2,
+  BABEL_AE_IP6_LL		= 3,
+  BABEL_AE_MAX
+};
+
+
+struct babel_config {
+  struct proto_config c;
+
+  list iface_list;              /* Patterns configured -- keep it first; see babel_reconfigure why */
+};
+
+struct babel_iface_config {
+  struct iface_patt i;
+
+  u16 rxcost;
+  u8 type;
+  u8 check_link;
+  int port;
+  u16 hello_interval;
+  u16 ihu_interval;
+  u16 update_interval;
+
+  u16 rx_buffer;			/* RX buffer size, 0 for MTU */
+  u16 tx_length;			/* TX packet length limit (including headers), 0 for MTU */
+  int tx_tos;
+  int tx_priority;
+};
+
+struct babel_proto {
+  struct proto p;
+  timer *timer;
+  struct fib rtable;
+  list interfaces;			/* Interfaces we really know about (struct babel_iface) */
+  u64 router_id;
+  u16 update_seqno;			/* To be increased on request */
+  u8 triggered;				/* For triggering global updates */
+
+  slab *route_slab;
+  slab *source_slab;
+  slab *msg_slab;
+
+  slab *seqno_slab;
+  list seqno_cache;			/* Seqno requests in the cache (struct babel_seqno_request) */
+
+  struct tbf log_pkt_tbf;		/* TBF for packet messages */
+};
+
+struct babel_iface {
+  node n;
+
+  struct babel_proto *proto;
+  struct iface *iface;
+
+  struct babel_iface_config *cf;
+
+  u8 up;
+
+  pool *pool;
+  char *ifname;
+  sock *sk;
+  ip_addr addr;
+  int tx_length;
+  list neigh_list;			/* List of neighbors seen on this iface (struct babel_neighbor) */
+  list msg_queue;
+
+  u16 hello_seqno;			/* To be increased on each hello */
+
+  bird_clock_t next_hello;
+  bird_clock_t next_regular;
+  bird_clock_t next_triggered;
+  bird_clock_t want_triggered;
+
+  timer *timer;
+  event *send_event;
+};
+
+struct babel_neighbor {
+  node n;
+  struct babel_iface *ifa;
+
+  ip_addr addr;
+  u16 txcost;
+  u8 hello_cnt;
+  u16 hello_map;
+  u16 next_hello_seqno;
+  /* expiry timers */
+  bird_clock_t hello_expiry;
+  bird_clock_t ihu_expiry;
+
+  list routes;				/* Routes this neighbour has sent us (struct babel_route) */
+};
+
+struct babel_source {
+  node n;
+
+  u64 router_id;
+  u16 seqno;
+  u16 metric;
+  bird_clock_t expires;
+};
+
+struct babel_route {
+  node n;
+  node neigh_route;
+  struct babel_entry    *e;
+  struct babel_neighbor *neigh;
+
+  u16 seqno;
+  u16 advert_metric;
+  u16 metric;
+  u64 router_id;
+  ip_addr next_hop;
+  bird_clock_t refresh_time;
+  bird_clock_t expires;
+  u16 expiry_interval;
+};
+
+struct babel_entry {
+  struct fib_node n;
+  struct babel_proto *proto;
+  struct babel_route *selected_in;
+  struct babel_route *selected_out;
+
+  bird_clock_t updated;
+
+  list sources;				/* Source entries for this prefix (struct babel_source). */
+  list routes;				/* Routes for this prefix (struct babel_route) */
+};
+
+/* Stores forwarded seqno requests for duplicate suppression. */
+struct babel_seqno_request {
+  node n;
+  ip_addr prefix;
+  u8  plen;
+  u64 router_id;
+  u16 seqno;
+  bird_clock_t updated;
+};
+
+
+/*
+ *	Internal TLV messages
+ */
+
+struct babel_msg_ack_req {
+  u8 type;
+  u16 nonce;
+  u16 interval;
+  ip_addr sender;
+};
+
+struct babel_msg_ack {
+  u8 type;
+  u16 nonce;
+};
+
+struct babel_msg_hello {
+  u8 type;
+  u16 seqno;
+  u16 interval;
+  ip_addr sender;
+};
+
+struct babel_msg_ihu {
+  u8 type;
+  u8 ae;
+  u16 rxcost;
+  u16 interval;
+  ip_addr addr;
+  ip_addr sender;
+};
+
+struct babel_msg_update {
+  u8 type;
+  u8 ae;
+  u8 plen;
+  u16 interval;
+  u16 seqno;
+  u16 metric;
+  ip_addr prefix;
+  u64 router_id;
+  ip_addr next_hop;
+  ip_addr sender;
+};
+
+struct babel_msg_route_request {
+  u8 type;
+  u8 full;
+  u8 plen;
+  ip_addr prefix;
+};
+
+struct babel_msg_seqno_request {
+  u8 type;
+  u8 plen;
+  u16 seqno;
+  u8 hop_count;
+  u64 router_id;
+  ip_addr prefix;
+  ip_addr sender;
+};
+
+union babel_msg {
+  u8 type;
+  struct babel_msg_ack_req ack_req;
+  struct babel_msg_ack ack;
+  struct babel_msg_hello hello;
+  struct babel_msg_ihu ihu;
+  struct babel_msg_update update;
+  struct babel_msg_route_request route_request;
+  struct babel_msg_seqno_request seqno_request;
+};
+
+struct babel_msg_node {
+  node n;
+  union babel_msg msg;
+};
+
+
+/* babel.c */
+void babel_handle_ack_req(union babel_msg *msg, struct babel_iface *ifa);
+void babel_handle_ack(union babel_msg *msg, struct babel_iface *ifa);
+void babel_handle_hello(union babel_msg *msg, struct babel_iface *ifa);
+void babel_handle_ihu(union babel_msg *msg, struct babel_iface *ifa);
+void babel_handle_router_id(union babel_msg *msg, struct babel_iface *ifa);
+void babel_handle_update(union babel_msg *msg, struct babel_iface *ifa);
+void babel_handle_route_request(union babel_msg *msg, struct babel_iface *ifa);
+void babel_handle_seqno_request(union babel_msg *msg, struct babel_iface *ifa);
+
+void babel_show_interfaces(struct proto *P, char *iff);
+void babel_show_neighbors(struct proto *P, char *iff);
+void babel_show_entries(struct proto *P);
+
+/* packets.c */
+void babel_enqueue(union babel_msg *msg, struct babel_iface *ifa);
+void babel_send_unicast(union babel_msg *msg, struct babel_iface *ifa, ip_addr dest);
+int babel_open_socket(struct babel_iface *ifa);
+void babel_send_queue(void *arg);
+
+
+#endif

proto/babel/config.Y

+/*
+ *	BIRD -- Babel Configuration
+ *
+ *	Copyright (c) 2015-2016 Toke Hoiland-Jorgensen
+ *
+ *	Can be freely distributed and used under the terms of the GNU GPL.
+ */
+
+
+
+CF_HDR
+
+#include "proto/babel/babel.h"
+#include "nest/iface.h"
+
+CF_DEFINES
+
+#define BABEL_CFG ((struct babel_config *) this_proto)
+#define BABEL_IFACE ((struct babel_iface_config *) this_ipatt)
+
+CF_DECLS
+
+CF_KEYWORDS(BABEL, METRIC, RXCOST, HELLO, UPDATE, INTERVAL, PORT, WIRED,
+WIRELESS, RX, TX, BUFFER, LENGTH, CHECK, LINK, BABEL_METRIC)
+
+CF_GRAMMAR
+
+CF_ADDTO(proto, babel_proto)
+
+babel_proto_start: proto_start BABEL
+{
+  this_proto = proto_config_new(&proto_babel, $1);
+  init_list(&BABEL_CFG->iface_list);
+};
+
+babel_proto_item:
+   proto_item
+ | INTERFACE babel_iface