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(trunk libT) web.c: add a cache for unresolvable hostnames

This commit is contained in:
Charles Kerr 2010-01-27 06:40:12 +00:00
parent 9c0900eb20
commit a888c4d425
1 changed files with 89 additions and 43 deletions
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132
libtransmission/web.c
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@ -19,6 +19,7 @@
#include "transmission.h"
#include "list.h"
#include "net.h"
#include "ptrarray.h"
#include "session.h"
#include "trevent.h"
#include "utils.h"
@ -61,7 +62,7 @@ struct tr_web
CURLM * multi;
tr_session * session;
tr_address addr;
tr_list * dns_cache;
tr_ptrArray dns_cache;
struct event timer_event;
};
@ -74,7 +75,7 @@ web_free( tr_web * g )
evdns_shutdown( TRUE );
curl_multi_cleanup( g->multi );
evtimer_del( &g->timer_event );
tr_list_free( &g->dns_cache, (TrListForeachFunc)dns_cache_item_free );
tr_ptrArrayDestruct( &g->dns_cache, (TrListForeachFunc)dns_cache_item_free );
memset( g, TR_MEMORY_TRASH, sizeof( struct tr_web ) );
tr_free( g );
}
@ -126,6 +127,7 @@ struct dns_cache_item
char * host;
char * resolved_host;
time_t expiration;
tr_bool success;
};
static void
@ -136,61 +138,95 @@ dns_cache_item_free( struct dns_cache_item * item )
tr_free( item );
}
static const char *
dns_get_cached_host( struct tr_web_task * task, const char * host )
static int
dns_cache_compare( const void * va, const void * vb )
{
tr_list * l;
tr_web * g = task->session->web;
struct dns_cache_item * item = NULL;
const struct dns_cache_item * a = va;
const struct dns_cache_item * b = vb;
return strcmp( a->host, b->host );
}
if( g != NULL )
static int
dns_cache_compare_key( const void * va, const void * key )
{
const struct dns_cache_item * a = va;
return strcmp( a->host, key );
}
typedef enum
{
TR_DNS_OK,
TR_DNS_FAIL,
TR_DNS_UNTESTED
}
tr_dns_result;
static tr_dns_result
dns_cache_lookup( struct tr_web_task * task, const char * host, const char ** resolved )
{
tr_dns_result result = TR_DNS_UNTESTED;
if( task->session->web != NULL )
{
/* do we have it cached? */
for( l=g->dns_cache; l!=NULL; l=l->next ) {
struct dns_cache_item * tmp = l->data;
if( !strcmp( host, tmp->host ) ) {
item = tmp;
break;
}
}
tr_ptrArray * cache = &task->session->web->dns_cache;
struct dns_cache_item * item = tr_ptrArrayFindSorted( cache, host,
dns_cache_compare_key );
/* has the ttl expired? */
if( ( item != NULL ) && ( item->expiration <= tr_time( ) ) ) {
tr_list_remove_data( &g->dns_cache, item );
if( ( item != NULL ) && ( item->expiration <= tr_time( ) ) )
{
tr_ptrArrayRemoveSorted( cache, host, dns_cache_compare_key );
dns_cache_item_free( item );
item = NULL;
}
if( item != NULL )
{
result = item->success ? TR_DNS_OK : TR_DNS_FAIL;
if( result == TR_DNS_OK )
{
*resolved = item->resolved_host;
dbgmsg( "found cached dns entry for \"%s\": %s", host, *resolved );
}
}
}
if( item != NULL )
dbgmsg( "found cached dns entry for \"%s\": %s",
host, item->resolved_host );
return result;
}
return item ? item->resolved_host : NULL;
static void
dns_cache_set_fail( struct tr_web_task * task, const char * host )
{
if( task->session->web != NULL )
{
struct dns_cache_item * item = tr_new( struct dns_cache_item, 1 );
item->host = tr_strdup( host );
item->resolved_host = NULL;
item->expiration = tr_time( ) + MIN_DNS_CACHE_TIME;
item->success = FALSE;
tr_ptrArrayInsertSorted( &task->session->web->dns_cache, item, dns_cache_compare );
}
}
static const char*
dns_set_cached_host( struct tr_web_task * task, const char * host,
const char * resolved, int ttl )
dns_cache_set_name( struct tr_web_task * task, const char * host,
const char * resolved, int ttl )
{
char * ret = NULL;
tr_web * g;
assert( task != NULL );
assert( host != NULL );
assert( resolved != NULL );
assert( ttl >= 0 );
ttl = MAX( MIN_DNS_CACHE_TIME, ttl );
g = task->session->web;
if( g != NULL )
if( task->session->web != NULL )
{
struct dns_cache_item * item = tr_new( struct dns_cache_item, 1 );
item->host = tr_strdup( host );
item->resolved_host = tr_strdup( resolved );
item->expiration = tr_time( ) + ttl;
tr_list_append( &g->dns_cache, item );
item->success = TRUE;
tr_ptrArrayInsertSorted( &task->session->web->dns_cache, item, dns_cache_compare );
ret = item->resolved_host;
dbgmsg( "adding dns cache entry for \"%s\": %s", host, resolved );
}
@ -259,7 +295,7 @@ addTask( void * vtask )
if( ( session == NULL ) || ( session->web == NULL ) )
return;
if( task->resolved_host == NULL )
if( !task->resolved_host )
{
dbgmsg( "couldn't resolve host for \"%s\"... task failed", task->url );
task_finish( task, 0 );
@ -361,7 +397,7 @@ dns_ipv6_done_cb( int err, char type, int count, int ttl, void * addresses, void
{
struct tr_web_task * task = vtask;
if( !err && ( task->host != NULL ) && ( count > 0 ) && ( ttl >= 0 ) && ( type == DNS_IPv6_AAAA ) )
if( !err && task->host && ( count>0 ) && ( ttl>=0 ) && ( type==DNS_IPv6_AAAA ) )
{
int i;
char buf[INET6_ADDRSTRLEN+1];
@ -371,12 +407,15 @@ dns_ipv6_done_cb( int err, char type, int count, int ttl, void * addresses, void
const char * b = inet_ntop(AF_INET6, &in6_addrs[i], buf,sizeof(buf));
if( b != NULL ) {
/* FIXME: is there a better way to tell which one to use if count > 1? */
task->resolved_host = dns_set_cached_host( task, task->host, b, ttl );
task->resolved_host = dns_cache_set_name( task, task->host, b, ttl );
break;
}
}
}
if( task->resolved_host == NULL )
dns_cache_set_fail( task, task->host );
addTask( task );
}
@ -385,11 +424,11 @@ dns_ipv4_done_cb( int err, char type, int count, int ttl, void * addresses, void
{
struct tr_web_task * task = vtask;
if( !err && ( task->host != NULL ) && ( count > 0 ) && ( ttl >= 0 ) && ( type == DNS_IPv4_A ) )
if( !err && task->host && ( count>0 ) && ( ttl>=0 ) && ( type==DNS_IPv4_A ) )
{
struct in_addr * in_addrs = addresses;
const char * resolved = inet_ntoa( in_addrs[0] );
task->resolved_host = dns_set_cached_host( task, task->host, resolved, ttl );
task->resolved_host = dns_cache_set_name( task, task->host, resolved, ttl );
/* FIXME: if count > 1, is there a way to decide which is best to use? */
}
@ -405,19 +444,25 @@ doDNS( void * vtask )
int port = -1;
char * host = NULL;
struct tr_web_task * task = vtask;
tr_dns_result lookup_result = TR_DNS_UNTESTED;
assert( task->resolved_host == NULL );
if( !tr_httpParseURL( task->url, -1, &host, &port, NULL ) ) {
if( !tr_httpParseURL( task->url, -1, &host, &port, NULL ) )
{
task->port = port;
task->host = host;
task->resolved_host = dns_get_cached_host( task, host );
lookup_result = dns_cache_lookup( task, host, &task->resolved_host );
}
if( ( task->resolved_host != NULL )
|| ( host == NULL )
|| evdns_resolve_ipv4( host, 0, dns_ipv4_done_cb, task ) )
if( lookup_result != TR_DNS_UNTESTED )
{
addTask( task );
}
else if( !host || evdns_resolve_ipv4( host, 0, dns_ipv4_done_cb, task ) )
{
dns_ipv4_done_cb( DNS_ERR_UNKNOWN, DNS_IPv4_A, 0, 0, NULL, task );
}
}
/***
@ -622,6 +667,7 @@ tr_webInit( tr_session * session )
curl_global_init( 0 );
web = tr_new0( struct tr_web, 1 );
web->dns_cache = TR_PTR_ARRAY_INIT;
web->session = session;
web->timer_msec = DEFAULT_TIMER_MSEC; /* overwritten by multi_timer_cb() */
evtimer_set( &web->timer_event, libevent_timer_cb, web );