From a9c25b9fed0b245496a40937ec343fa306dc252e Mon Sep 17 00:00:00 2001 From: erdgeist <> Date: Tue, 14 Jul 2009 12:32:41 +0000 Subject: [PATCH] Reloading accesslists left a wide window for race conditions. --- ot_accesslist.c | 28 +++++++++++++++++++--------- 1 file changed, 19 insertions(+), 9 deletions(-) diff --git a/ot_accesslist.c b/ot_accesslist.c index 4eb63a7..e57f09e 100644 --- a/ot_accesslist.c +++ b/ot_accesslist.c @@ -34,9 +34,9 @@ void accesslist_deinit( void ) { accesslist_reset( ); } -static int accesslist_addentry( ot_hash infohash ) { +static int accesslist_addentry( ot_vector *al, ot_hash infohash ) { int eger; - void *insert = vector_find_or_insert( &accesslist, infohash, OT_HASH_COMPARE_SIZE, OT_HASH_COMPARE_SIZE, &eger ); + void *insert = vector_find_or_insert( al, infohash, OT_HASH_COMPARE_SIZE, OT_HASH_COMPARE_SIZE, &eger ); if( !insert ) return -1; @@ -48,22 +48,24 @@ static int accesslist_addentry( ot_hash infohash ) { /* Read initial access list */ static void accesslist_readfile( int sig ) { - FILE * accesslist_filehandle; - ot_hash infohash; - char inbuf[512]; + FILE * accesslist_filehandle; + ot_hash infohash; + ot_vector accesslist_tmp; + void *olddata = accesslist.data; + char inbuf[512]; if( sig != SIGHUP ) return; accesslist_filehandle = fopen( g_accesslist_filename, "r" ); - /* Free accesslist vector in trackerlogic.c*/ - accesslist_reset(); - if( accesslist_filehandle == NULL ) { fprintf( stderr, "Warning: Can't open accesslist file: %s (but will try to create it later, if necessary and possible).", g_accesslist_filename ); return; } + /* Initialise an empty accesslist vector */ + memset( &accesslist_tmp, 0, sizeof(accesslist_tmp)); + /* We do ignore anything that is not of the form "^[:xdigit:]{40}[^:xdigit:].*" */ while( fgets( inbuf, sizeof(inbuf), accesslist_filehandle ) ) { int i; @@ -77,10 +79,18 @@ static void accesslist_readfile( int sig ) { continue; /* Append accesslist to accesslist vector */ - accesslist_addentry( infohash ); + accesslist_addentry( &accesslist_tmp, infohash ); } +#ifdef _DEBUG + fprintf( stderr, "Added %zd info_hashes to accesslist\n", accesslist_tmp.size ); +#endif fclose( accesslist_filehandle ); + + /* Now exchange the accesslist vector in the least race condition prone way */ + accesslist.size = 0; + memcpy( &accesslist, &accesslist_tmp, sizeof( &accesslist_tmp )); + free( olddata ); } int accesslist_hashisvalid( ot_hash hash ) {