From 0e1e632f70b74cf111f08175ab3634db2f962579 Mon Sep 17 00:00:00 2001 From: Maria Matejka Date: Thu, 31 Mar 2022 19:00:00 +0200 Subject: FIB is a data structure generic enough to be in lib --- lib/fib.h | 119 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 119 insertions(+) create mode 100644 lib/fib.h (limited to 'lib/fib.h') diff --git a/lib/fib.h b/lib/fib.h new file mode 100644 index 00000000..bec2a8d4 --- /dev/null +++ b/lib/fib.h @@ -0,0 +1,119 @@ +/* + * BIRD Internet Routing Daemon -- Network prefix storage + * + * (c) 1998--2000 Martin Mares + * (c) 2022 Maria Matejka + * + * Can be freely distributed and used under the terms of the GNU GPL. + */ + +#ifndef _BIRD_LIB_FIB_H_ +#define _BIRD_LIB_FIB_H_ + +/* + * BIRD FIBs are generic data structure for storing network prefixes. + * Also used for the master routing table. Currently implemented as + * a hash table. + * + * Available operations: + * - insertion of new entry + * - deletion of entry + * - searching for entry by network prefix + * - asynchronous retrieval of fib contents + */ + +struct fib; + +struct fib_node { + struct fib_node *next; /* Next in hash chain */ + struct fib_iterator *readers; /* List of readers of this node */ + net_addr addr[0]; +}; + +struct fib_iterator { /* See lib/slists.h for an explanation */ + struct fib_iterator *prev, *next; /* Must be synced with struct fib_node! */ + byte efef; /* 0xff to distinguish between iterator and node */ + byte pad[3]; + struct fib_node *node; /* Or NULL if freshly merged */ + uint hash; +}; + +typedef void (*fib_init_fn)(struct fib *, void *); + +struct fib { + pool *fib_pool; /* Pool holding all our data */ + slab *fib_slab; /* Slab holding all fib nodes */ + struct fib_node **hash_table; /* Node hash table */ + uint hash_size; /* Number of hash table entries (a power of two) */ + uint hash_order; /* Binary logarithm of hash_size */ + uint hash_shift; /* 32 - hash_order */ + uint addr_type; /* Type of address data stored in fib (NET_*) */ + uint node_size; /* FIB node size, 0 for nonuniform */ + uint node_offset; /* Offset of fib_node struct inside of user data */ + uint entries; /* Number of entries */ + uint entries_min, entries_max; /* Entry count limits (else start rehashing) */ + fib_init_fn init; /* Constructor */ +}; + +static inline void * fib_node_to_user(struct fib *f, struct fib_node *e) +{ return e ? (void *) ((char *) e - f->node_offset) : NULL; } + +static inline struct fib_node * fib_user_to_node(struct fib *f, void *e) +{ return e ? (void *) ((char *) e + f->node_offset) : NULL; } + +void fib_init(struct fib *f, pool *p, uint addr_type, uint node_size, uint node_offset, uint hash_order, fib_init_fn init); +void *fib_find(struct fib *, const net_addr *); /* Find or return NULL if doesn't exist */ +void *fib_get_chain(struct fib *f, const net_addr *a); /* Find first node in linked list from hash table */ +void *fib_get(struct fib *, const net_addr *); /* Find or create new if nonexistent */ +void *fib_route(struct fib *, const net_addr *); /* Longest-match routing lookup */ +void fib_delete(struct fib *, void *); /* Remove fib entry */ +void fib_free(struct fib *); /* Destroy the fib */ +void fib_check(struct fib *); /* Consistency check for debugging */ + +void fit_init(struct fib_iterator *, struct fib *); /* Internal functions, don't call */ +struct fib_node *fit_get(struct fib *, struct fib_iterator *); +void fit_put(struct fib_iterator *, struct fib_node *); +void fit_put_next(struct fib *f, struct fib_iterator *i, struct fib_node *n, uint hpos); +void fit_put_end(struct fib_iterator *i); +void fit_copy(struct fib *f, struct fib_iterator *dst, struct fib_iterator *src); + + +#define FIB_WALK(fib, type, z) do { \ + struct fib_node *fn_, **ff_ = (fib)->hash_table; \ + uint count_ = (fib)->hash_size; \ + type *z; \ + while (count_--) \ + for (fn_ = *ff_++; z = fib_node_to_user(fib, fn_); fn_=fn_->next) + +#define FIB_WALK_END } while (0) + +#define FIB_ITERATE_INIT(it, fib) fit_init(it, fib) + +#define FIB_ITERATE_START(fib, it, type, z) do { \ + struct fib_node *fn_ = fit_get(fib, it); \ + uint count_ = (fib)->hash_size; \ + uint hpos_ = (it)->hash; \ + type *z; \ + for(;;) { \ + if (!fn_) \ + { \ + if (++hpos_ >= count_) \ + break; \ + fn_ = (fib)->hash_table[hpos_]; \ + continue; \ + } \ + z = fib_node_to_user(fib, fn_); + +#define FIB_ITERATE_END fn_ = fn_->next; } } while(0) + +#define FIB_ITERATE_PUT(it) fit_put(it, fn_) + +#define FIB_ITERATE_PUT_NEXT(it, fib) fit_put_next(fib, it, fn_, hpos_) + +#define FIB_ITERATE_PUT_END(it) fit_put_end(it) + +#define FIB_ITERATE_UNLINK(it, fib) fit_get(fib, it) + +#define FIB_ITERATE_COPY(dst, src, fib) fit_copy(fib, dst, src) + +#endif -- cgit v1.2.3