First look at data structures. More to come tomorrow...

Makefile

+# Makefile for the BIRD Internet Routing Daemon
+# (c) 1998 Martin Mares <mj@ucw.cz>
+
+TOPDIR=$(shell pwd)
+CFLAGS=-O2 -Wall -W -Wstrict-prototypes -Wno-unused -Wno-parentheses -I$(TOPDIR)
+
+PROTOCOLS=
+DIRS=sysdep/linux nest $(protocols) lib
+ARCHS=$(join $(addsuffix /,$(DIRS)),$(subst /,_,$(addsuffix .a,$(DIRS))))
+
+export
+
+all: all-dirs bird
+
+all-dirs:
+	set -e ; for a in $(DIRS) ; do $(MAKE) -C $$a ; done
+
+bird: $(ARCHS)
+	$(CC) $(LDFLAGS) -o $@ $^
+
+clean:
+	rm -f `find . -name "*~" -or -name "*.[oa]" -or -name "\#*\#" -or -name TAGS -or -name core`
+	rm -f bird

Rules

+# Makefile for the BIRD Internet Routing Daemon
+# (c) 1998 Martin Mares <mj@ucw.cz>
+
+THISDIR=$(shell pwd)
+RELDIR=$(subst $(TOPDIR)/,,$(THISDIR))
+ANAME=$(subst /,_,$(RELDIR)).a
+
+all: $(ANAME)
+
+$(ANAME): $(OBJS)
+	rm -f $(ANAME)
+	ar rcs $(ANAME) $(OBJS)

TODO

+Core
+~~~~
+- route validation
+- fake multipath?
+- config file: symbolic constants?
+- counters (according to SNMP MIB?)
+- generation of subnet mask ICMP's for v6?
+- debugging dumps and protocol tracing!
+- unaligned accesses?
+
+
+RIP
+~~~
+- RIP: export-only and import-only mode?
+- drop RIPv1 (Historic protocol)?
+
+OSPF
+~~~~
+
+Almquist & Kastenholz                                         [Page 111]
+RFC 1716          Towards Requirements for IP Routers      November 1994
+
+
+7.2.2.2  Specific Issues
+
+         Virtual Links
+
+              There is a minor error in the specification that can cause
+              routing loops when all of the following conditions are
+              simultaneously true:
+
+              (1)  A virtual link is configured through a transit area,
+
+              (2)  Two separate paths exist, each having the same
+                   endpoints, but one utilizing only non-virtual
+                   backbone links, and the other using links in the
+                   transit area, and
+
+              (3)  The latter path is part of the (underlying physical
+                   representation of the) configured virtual link,
+                   routing loops may occur.
+
+              To prevent this, an implementation of OSPF SHOULD invoke
+              the calculation in Section 16.3 of [ROUTE:1] whenever any
+              part of the path to the destination is a virtual link (the
+              specification only says this is necessary when the first
+              hop is a virtual link).
+
+BGP
+~~~
+- BGP:
+	- in, local, out RIB
+	- maxsize=4096
+	- BGP identifier aka router id
+	- removal of loops
+	- aggregation, ATOMIC_AGGREGATE
+	- communities
+	- confederations
+	- attributes must be sorted!
+	- re-export of NEXT_HOP attribute
+	- BGP session over currently down interface
+	- route flap dampening?
+	- LOCAL_PREF attribute
+	- error notification received -> log error
+	- set TTL to 1 (configurable?)
+	- consulting IGP for next-hop information? (what if it changes?)
+	- inter-advertisement delay???!
+	- normalize (sort) incoming AS-SET's
+	- maximum length of AS paths
+
+	- expected neighbor AS
+	- hold time
+	- idle timer after error: initial value, exponential growth, maximum value
+
+- address testing macros (ALL_ZEROS)
+- all internal tables are in network order (?)
+- logging of errors and debug dumps
+- filter: logging of dropped routes (?)
+- limitation of memory consumption: per-process and total
+- alloca
+- precedence of all packets (incl. TCP)
+- adding of route: clear all bits not covered by masklen
+- switch: generate default route only if at least one BGP connection exists
+
+- route update: new, change, remove
+- route recalculation timing
+
+- CONFIG_TOS
+- CONFIG_MULTIPATH
+
+- reconfiguration without restart of all protocols?
+- change of interface address: ??? (down and up?)
+- "generate default route" switch for all IGP's
+
+- RIPv2:
+	- Route Tag
+	- limit routing table xfer (frequency, only to neighbors)
+	- multicast on/off
+	- remember routes for all neighbors?
+
+- BGP:
+	- import of IGP routes (use external route tags from OSPF)
+
+- Interface:
+	- RIP metric
+	- multicast capability flag
+	- MTU
+	- OSPF metrics (per-TOS)
+
+- running protocol on an interface:
+	- interface is not required to exist
+	- can specify a wildcard pattern or an interface list
+
+- preferences:
+	- directly connected
+	- static
+	- OSPF internal, OSPF ext type 1 (comparable metrics), OSPF inter-area
+	- RIP
+	- BGP
+	- OSPF ext type 2
+	- sink
+
+- lib:
+	- MD5
+
+- OSPF:
+	- Dijkstra: use Fibonacci heaps?
+	- point-to-point interface with address: advertise as stub network
+	- static routes: stub networks?
+	- modes: PtP, PtP-unnumbered, Broadcast, NBMA, point-to-multipoint
+	- importing of device routes for networks where we don't run OSPF
+	- tie breaking for equal type 2 ext metrics by using internal (type 1) metric
+	- SPF tree recalc timing (per-area timers?)
+	- aggregation: specify network list for each area
+	- stub area: either no external routes or only default route
+	- automatic generation of external route tags (RFC1403) -- what about
+	  using the same rule for RIPv2? [shared code?]
+
+- timers - one-shot and periodic, resolution 1 sec, randomized
+- re-configuration: restart of routing protocols (shutdown mode)
+- route: originating AS
+
+- Check incoming packets and log errors!!

lib/Makefile

+OBJS=lists.o
+
+include $(TOPDIR)/Rules

lib/birdlib.h

+/*
+ *	BIRD Library
+ *
+ *	(c) 1998 Martin Mares <mj@ucw.cz>
+ *
+ *	Can be freely distributed and used under the terms of the GNU GPL.
+ */
+
+#ifndef _BIRD_BIRDLIB_H_
+#define _BIRD_BIRDLIB_H_
+
+/* Ugly structure offset handling macros */
+
+#define OFFSETOF(s, i) ((unsigned int)&((s *)0)->i)
+#define SKIP_BACK(s, i, p) ((s *)((char *)p - OFFSETOF(s, i)))
+
+#endif

lib/lists.c

+/*
+ *	BIRD Library -- Linked Lists
+ *
+ *	(c) 1998 Martin Mares <mj@ucw.cz>
+ *
+ *	Can be freely distributed and used under the terms of the GNU GPL.
+ */
+
+#define _BIRD_LISTS_C_
+
+#include <nest/bird.h>
+#include <lib/lists.h>
+
+LIST_INLINE void
+add_tail(list *l, node *n)
+{
+  node *z = l->tail;
+
+  n->next = (node *) &l->tail;
+  n->prev = z;
+  z->next = n;
+  l->tail = n;
+}
+
+LIST_INLINE void
+add_head(list *l, node *n)
+{
+  node *z = l->head;
+
+  n->next = z;
+  n->prev = (node *) &l->head;
+  z->prev = n;
+  l->head = n;
+}
+
+LIST_INLINE void
+insert_node(node *n, node *after)
+{
+  node *z = after->next;
+
+  n->next = z;
+  n->prev = after;
+  after->next = n;
+  z->prev = n;
+}
+
+LIST_INLINE void
+rem_node(node *n)
+{
+  node *z = n->prev;
+  node *x = n->next;
+
+  z->next = x;
+  x->prev = z;
+}
+
+LIST_INLINE void
+init_list(list *l)
+{
+  l->head = (node *) &l->null;
+  l->null = NULL;
+  l->tail = (node *) &l->head;
+}
+
+LIST_INLINE void
+add_tail_list(list *to, list *l)
+{
+  node *p = to->tail;
+  node *q = l->head;
+
+  p->next = q;
+  q->prev = p;
+  q = l->tail;
+  q->next = (node *) &to->null;
+  to->tail = q;
+}

lib/lists.h

+/*
+ *	BIRD Library -- Linked Lists
+ *
+ *	(c) 1998 Martin Mares <mj@ucw.cz>
+ *
+ *	Can be freely distributed and used under the terms of the GNU GPL.
+ */
+
+#ifndef _BIRD_LISTS_H_
+#define _BIRD_LISTS_H_
+
+typedef struct node {
+  struct node *next, *prev;
+} node;
+
+typedef struct list {			/* In fact two overlayed nodes */
+  struct node *head, *null, *tail;
+} list;
+
+#define NODE (node *)
+#define HEAD(list) ((void *)((list).head))
+#define TAIL(list) ((void *)((list).tail))
+#define WALK_LIST(n,list) for((n)=HEAD(list);(NODE (n))->next; \
+				n=(void *)((NODE (n))->next))
+#define EMPTY_LIST(list) (!(list).head->next)
+
+void add_tail(list *, node *);
+void add_head(list *, node *);
+void rem_node(node *);
+void add_tail_list(list *, list *);
+void init_list(list *);
+void insert_node(node *, node *);
+
+#ifndef _BIRD_LISTS_C_
+#define LIST_INLINE extern inline
+#include <lib/lists.c>
+#undef LIST_INLINE
+#else
+#define LIST_INLINE
+#endif
+
+#endif

lib/resource.h

+/*
+ *	BIRD Resource Manager
+ *
+ *	(c) 1998 Martin Mares <mj@ucw.cz>
+ *
+ *	Can be freely distributed and used under the terms of the GNU GPL.
+ */
+
+#ifndef _BIRD_RESOURCE_H_
+#define _BIRD_RESOURCE_H_
+
+#include <lib/lists.h>
+
+/* Resource */
+
+typedef struct resource {
+	node n;				/* Inside resource pool */
+	struct resclass *class;		/* Resource class */
+} resource;
+
+/* Resource class */
+
+struct resclass {
+	char *name;			/* Resource class name */
+	unsigned size;			/* Standard size of single resource */
+	void (*free)(resource *);	/* Freeing function */
+	void (*dump)(resource *);	/* Dump to debug output */
+};
+
+/* Generic resource manipulation */
+
+typedef struct pool pool;
+
+pool *rp_new(pool *);			/* Create new pool */
+void rp_init(pool *);			/* Initialize static pool */
+void rp_empty(pool *);			/* Free everything in the pool */
+void rfree(void *);			/* Free single resource */
+void rdump(void *);			/* Dump to debug output */
+
+void ralloc(pool *, struct resclass *);
+
+/* Normal memory blocks */
+
+void *mb_alloc(pool *, unsigned size);
+void *mb_free(void *);
+
+/* Memory pools with linear allocation */
+
+typedef struct mempool mempool;
+
+mempool *mp_new(pool *, unsigned blk);
+void mp_trim(pool *);				/* Free unused memory */
+void *mp_alloc(mempool *, unsigned size);	/* Aligned */
+void *mp_allocu(mempool *, unsigned size);	/* Unaligned */
+void *mp_allocz(mempool *, unsigned size);	/* With clear */
+
+/* Slabs */
+
+typedef struct slab slab;
+
+slab *sl_new(pool *, unsigned size);
+void *sl_alloc(slab *);
+void sl_free(slab *, void *);
+
+/* Low-level memory allocation functions, please don't use */
+
+void *xmalloc(unsigned);
+#define xfree(x) free(x)
+
+#endif

lib/socket.h

+/*
+ *	BIRD Socket Interface
+ *
+ *	(c) 1998 Martin Mares <mj@ucw.cz>
+ *
+ *	Can be freely distributed and used under the terms of the GNU GPL.
+ */
+
+#ifndef _BIRD_SOCKET_H_
+#define _BIRD_SOCKET_H_
+
+#include <lib/resource.h>
+
+typedef struct birdsock socket;
+
+#endif

lib/timer.h

+/*
+ *	BIRD Timers
+ *
+ *	(c) 1998 Martin Mares <mj@ucw.cz>
+ *
+ *	Can be freely distributed and used under the terms of the GNU GPL.
+ */
+
+#ifndef _BIRD_TIMER_H_
+#define _BIRD_TIMER_H_
+
+#include <lib/resource.h>
+
+typedef struct timer {
+	resource r;
+	void (*hook)(struct timer *);
+	void *data;
+	/* internal fields should be here */
+} timer;
+
+timer *tm_new(pool *, void (*hook)(timer *), void *data);
+void tm_start(timer *, unsigned after);
+void tm_stop(timer *);
+void tm_trigger(timer *);
+
+#endif

lib/unaligned.h

+/*
+ *	Unaligned Data Accesses
+ *
+ *	(c) 1998 Martin Mares <mj@ucw.cz>
+ *
+ *	Can be freely distributed and used under the terms of the GNU GPL.
+ */
+
+#ifndef _BIRD_UNALIGNED_H_
+#define _BIRD_UNALIGNED_H_
+
+#endif

nest/Makefile

+OBJS=main.o
+
+include $(TOPDIR)/Rules

nest/bird.h

+/*
+ *	BIRD Internet Routing Daemon -- Basic Declarations
+ *
+ *	(c) 1998 Martin Mares <mj@ucw.cz>
+ *
+ *	Can be freely distributed and used under the terms of the GNU GPL.
+ */
+
+#ifndef _BIRD_BIRD_H_
+#define _BIRD_BIRD_H_
+
+#include <sysdep/config.h>
+#include <lib/birdlib.h>
+
+#ifndef IPV6
+#include <nest/ipv4.h>
+#else
+#include <nest/ipv6.h>
+#endif
+
+extern u32 router_id;			/* Our Router ID */
+extern u16 this_as;			/* Our Autonomous System Number */
+
+#endif

nest/confile.h

+/*
+ *	BIRD Internet Routing Daemon -- Configuration File
+ *
+ *	(c) 1998 Martin Mares <mj@ucw.cz>
+ *
+ *	Can be freely distributed and used under the terms of the GNU GPL.
+ */
+
+#ifndef _BIRD_CONFILE_H_
+#define _BIRD_CONFILE_H_
+
+#endif

nest/iface.h

+/*
+ *	BIRD Internet Routing Daemon -- Network Interfaces
+ *
+ *	(c) 1998 Martin Mares <mj@ucw.cz>
+ *
+ *	Can be freely distributed and used under the terms of the GNU GPL.
+ */
+
+#ifndef _BIRD_IFACE_H_
+#define _BIRD_IFACE_H_
+
+#endif

nest/ipv4.h

+/*
+ *	BIRD -- IP Addresses et Cetera for IPv4
+ *
+ *	(c) 1998 Martin Mares <mj@ucw.cz>
+ *
+ *	Can be freely distributed and used under the terms of the GNU GPL.
+ */
+
+#ifndef _BIRD_IPV4_H_
+#define _BIRD_IPV4_H_
+
+#include <netinet/in.h>
+
+typedef struct ipv4_addr {
+  u32 addr;
+} ip_addr;
+
+#define ipa_equal(x,y) ((x).addr == (y).addr)
+
+#endif

nest/ipv6.h

+/*
+ *	BIRD -- IP Addresses et Cetera for IPv6
+ *
+ *	(c) 1998 Martin Mares <mj@ucw.cz>
+ *
+ *	Can be freely distributed and used under the terms of the GNU GPL.
+ */
+
+#ifndef _BIRD_IPV4_H_
+#define _BIRD_IPV4_H_
+
+#include <netinet/in.h>
+#include <string.h>
+
+typedef struct ipv4_addr {
+  u32 addr[4];
+} ip_addr;
+
+#define ipa_equal(x,y) (!memcmp(&(x),&(y),sizeof(ip_addr)))
+
+#endif

nest/main.c

+/*
+ *	BIRD Internet Routing Daemon
+ *
+ *	(c) 1998 Martin Mares <mj@ucw.cz>
+ *
+ *	Can be freely distributed and used under the terms of the GNU GPL.
+ */
+
+#include <nest/bird.h>
+#include <lib/lists.h>
+
+#include <nest/resource.h>
+
+int
+main(void)
+{
+	ip_addr x,y;
+
+	x=y;
+	if (ipa_equal(x,y)) return 1;
+
+	return 0;
+}

nest/protocol.h

+/*
+ *	BIRD Internet Routing Daemon -- Protocols
+ *
+ *	(c) 1998 Martin Mares <mj@ucw.cz>
+ *
+ *	Can be freely distributed and used under the terms of the GNU GPL.
+ */
+
+#ifndef _BIRD_PROTOCOL_H_
+#define _BIRD_PROTOCOL_H_
+
+#include <lib/resource.h>
+
+/*
+ *	Routing Protocol
+ */
+
+struct protocol {
+  char *name;
+  unsigned type;			/* ??? List values ??? */
+  unsigned debug;			/* Default debugging flags */
+
+  void (*init)(struct protocol *);	/* Boot time */
+  void (*preconfig)(struct protocol *);	/* Just before configuring */
+  void (*postconfig)(struct protocol *); /* After configuring */
+};
+
+void protos_init(void);
+void protos_preconfig(void);
+void protos_postconfig(void);
+
+/*
+ *	Known protocols
+ */
+
+extern struct protocol proto_static;
+
+/*
+ *	Routing Protocol Instance
+ */
+
+struct proto {
+  struct proto *next;
+  struct protocol *proto;		/* Protocol */
+  char *name;				/* Name of this instance */
+  unsigned debug;			/* Debugging flags */
+  pool *pool;				/* Local objects */
+  unsigned preference;			/* Default route preference */
+
+  void (*if_notify)(struct proto *, struct iface *old, struct iface *new);
+  void (*rt_notify)(struct proto *, struct rte *old, struct rte *new);
+  void (*debug)(struct proto *);		/* Debugging dump */
+  void (*start)(struct proto *);		/* Start the instance */
+  void (*shutdown)(struct proto *, int time);	/* Stop the instance */
+
+  /* Reconfigure function? */
+  /* Interface patterns */
+  /* Input/output filters */
+  /* Connection to routing tables? */
+
+  /* Hic sunt protocol-specific data */
+};
+
+void *proto_new(struct protocol *, unsigned size);
+
+#endif

nest/route.h

+/*
+ *	BIRD Internet Routing Daemon -- Routing Table
+ *
+ *	(c) 1998 Martin Mares <mj@ucw.cz>
+ *
+ *	Can be freely distributed and used under the terms of the GNU GPL.
+ */
+
+#ifndef _BIRD_ROUTE_H_
+#define _BIRD_ROUTE_H_
+
+#include <lib/resource.h>
+
+/*
+ *	Generic data structure for storing network prefixes. Also used
+ *	for the master routing table. Currently implemented as a radix
+ *	trie.
+ *
+ *	Available operations:
+ *		- insertion of new entry
+ *		- deletion of entry
+ *		- searching of entry by network prefix
+ *		- searching of entry by IP address (longest match)
+ */