diff options
Diffstat (limited to 'bgpd/bgp_peer_index.c')
| -rw-r--r-- | bgpd/bgp_peer_index.c | 87 |
1 files changed, 67 insertions, 20 deletions
diff --git a/bgpd/bgp_peer_index.c b/bgpd/bgp_peer_index.c index 5bb7f3d0..518a22bc 100644 --- a/bgpd/bgp_peer_index.c +++ b/bgpd/bgp_peer_index.c @@ -24,6 +24,7 @@ #include "bgpd/bgp_peer_index.h" #include "bgpd/bgp_peer.h" #include "bgpd/bgp_session.h" +#include "bgpd/bgp_connection.h" #include "lib/symtab.h" #include "lib/vector.h" @@ -35,17 +36,26 @@ * BGP Peer Index * * When peers are created, they are registered in the bgp_peer_index. When - * they are destroyed, they are removed. This is done by the Routeing Engine. + * they are destroyed, they are removed. This is done by the Routing Engine. * - * The peer index is used by the Routeing Engine to lookup peers either by + * The Peer Index is used by the Routing Engine to lookup peers either by * name (IP address) or by peer_id. * * The BGP Engine needs to lookup sessions when a listening socket accepts a * connection -- first, to decide whether to continue with the connection, and - * second, to tie the connection to the right session. It uses the peer index + * second, to tie the connection to the right session. It uses the Peer Index * to do this. * - * A mutex is used to coordinate access to the index. + * A mutex is used to coordinate access to the index. Only the Routing engine + * makes changes to the Peer Index, so it only needs to lock the mutex when it + * does make changes. The BGP Engine needs to lock the Peer Index whenever it + * accesses it. + * + * The BGP Engine needs the session associated with a given address if and only + * if the session is enabled for accept(), which implies that it is active and + * in the hands of the BGP Engine. To get to the session it needs to step + * via the peer->session pointer, having found the peer via the index. So, + * setting the peer->session pointer is done under the Peer Index Mutex. */ static struct symbol_table bgp_peer_index ; /* lookup by 'name' */ @@ -140,7 +150,7 @@ bgp_peer_index_reset(void) /* Ream out the peer id vector -- checking that all entries are empty */ while ((entry = vector_ream_keep(&bgp_peer_id_index)) != NULL) - passert(entry->peer == NULL) ; + passert((entry->peer == NULL) && (entry->next_free != entry)) ; /* Discard body of symbol table -- must be empty ! */ symbol_table_reset_keep(&bgp_peer_index) ; @@ -192,13 +202,14 @@ bgp_peer_index_register(bgp_peer peer, union sockunion* su) bgp_peer_id_table_make_ids() ; entry = bgp_peer_id_free_head ; - bgp_peer_id_free_head = (void*)entry->accept ; + bgp_peer_id_free_head = entry->next_free ; assert(vector_get_item(&bgp_peer_id_index, entry->id) == entry) ; /* Initialise the entry -- the id is already set */ entry->peer = peer ; - entry->accept = NULL ; + entry->next_free = entry ; + peer->index_entry = entry; /* Insert the new entry into the symbol table. */ @@ -235,7 +246,9 @@ bgp_peer_index_deregister(bgp_peer peer, union sockunion* su) entry = symbol_delete(sym) ; - passert((entry != NULL) && (entry->peer == peer) && (entry->accept == NULL)) ; + passert( (entry != NULL) && (entry->id != bgp_peer_id_null) + && (entry->peer == peer) + && (entry->next_free == entry) ) ; bgp_peer_id_table_free_entry(entry) ; @@ -271,21 +284,47 @@ bgp_peer_index_seek(union sockunion* su) extern bgp_peer_index_entry bgp_peer_index_seek_entry(union sockunion* su) { + bgp_peer_index_entry entry ; + /* Only the Routing Engine can add/delete entries -- so no lock required */ - return symbol_get_value(symbol_seek(&bgp_peer_index, su)) ; + entry = symbol_get_value(symbol_seek(&bgp_peer_index, su)) ; + + if (entry != NULL) + assert((entry->peer != NULL) && (entry->next_free = entry)) ; + + return entry ; } ; /*------------------------------------------------------------------------------ - * Lookup a peer by its address. + * Set peer->session field. * - * Return a pointer to its session iff it is prepared to accept() a connection. + * This is done under the Peer Index Mutex, so that the BGP Engine can step + * from the Peer Index entry, via the peer structure, to the session, which is + * also controlled by that Mutex, in safety. + */ +extern void +bgp_peer_index_set_session(bgp_peer peer, bgp_session session) +{ + BGP_PEER_INDEX_LOCK() ; /*<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<*/ + + peer->session = session ; + + BGP_PEER_INDEX_UNLOCK() ; /*>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>*/ +} ; + +/*------------------------------------------------------------------------------ + * Find whether given address is for a known peer, and if so whether it has + * an active session which is prepared to accept() a connection. * * For use by the BGP Engine. * * Returns: bgp_connection if: peer with given address is configured * and: the session is prepared to accept() * + * Note that the session cannot be deleted while it is in a prepared + * to accept state. + * * or: NULL otherwise * * Sets *p_found <=> a peer with the given address is configured. @@ -294,17 +333,25 @@ bgp_peer_index_seek_entry(union sockunion* su) * is initialised NULL when the index entry is created. */ extern bgp_connection -bgp_peer_index_seek_accept(union sockunion* su, int* p_found) +bgp_peer_index_seek_accept(union sockunion* su, bool* p_found) { - bgp_connection accept ; + bgp_connection accept ; bgp_peer_index_entry entry ; BGP_PEER_INDEX_LOCK() ; /*<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<*/ entry = symbol_get_value(symbol_seek(&bgp_peer_index, su)) ; - *p_found = (entry != NULL) ; - accept = *p_found ? entry->accept : NULL ; + if (entry != NULL) + { + *p_found = true ; + accept = bgp_connection_query_accept(entry->peer->session) ; + } + else + { + *p_found = false ; + accept = NULL ; + } ; BGP_PEER_INDEX_UNLOCK() ; /*>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>*/ @@ -333,10 +380,10 @@ bgp_peer_id_table_free_entry(bgp_peer_index_entry entry) if (bgp_peer_id_free_head == NULL) bgp_peer_id_free_head = entry ; else - bgp_peer_id_free_tail->accept = (void*)entry ; + bgp_peer_id_free_tail->next_free = entry ; bgp_peer_id_free_tail = entry ; - entry->accept = NULL ; /* used as 'next' for free list */ + entry->next_free = NULL ; entry->peer = NULL ; /* only when free ! */ } ; @@ -363,9 +410,9 @@ bgp_peer_id_table_make_ids(void) { confirm(bgp_peer_id_null == 0) ; - entry->id = 0 ; /* should never be used */ - entry->peer = NULL ; /* invalid in use */ - entry->accept = (void*)entry ; /* invalid if not active ! */ + entry->id = 0 ; /* should never be used */ + entry->peer = NULL ; /* invalid in use */ + entry->next_free = NULL ; /* invalid in use */ ++entry ; /* step past id == 0 */ id_new = 1 ; /* avoid setting id == 0 free */ |