+ int res;
+
+ // zero dnsengine_cares_sockets array
+ memset(dnsengine_cares_sockets, 0, sizeof(*dnsengine_cares_sockets) * ARES_GETSOCK_MAXNUM);
+
+ // initialize cares
+ if((res = ares_init(&dnsengine_cares_channel)) != ARES_SUCCESS) {
+ iolog_trigger(IOLOG_ERROR, "Failed to initialize c-ares in %s:%d", __FILE__, __LINE__);
+ return 0;
+ }
+ return 0; /* backend not completed */
+}
+
+static void dnsengine_cares_update_sockets() {
+ int ares_socks[ARES_GETSOCK_MAXNUM];
+ memset(ares_socks, 0, sizeof(*ares_socks) * ARES_GETSOCK_MAXNUM);
+ int sockreqs = ares_getsock(dnsengine_cares_channel, ares_socks, ARES_GETSOCK_MAXNUM);
+ int i, j, sockid, newsock, updatesock;
+ struct _IOSocket *iosock;
+
+ //unregister "old" sockets
+ for(i = 0; i < ARES_GETSOCK_MAXNUM; i++) {
+ if(!dnsengine_cares_sockets[i].iosock)
+ continue;
+
+ //search matching ares_socks
+ sockid = -1;
+ for(j = 0; j < ARES_GETSOCK_MAXNUM; j++) {
+ if(dnsengine_cares_sockets[i].iosock->fd == ares_socks[j]) {
+ sockid = j;
+ break;
+ }
+ }
+ if(sockid == -1) {
+ //unregister socket
+ _free_socket(dnsengine_cares_sockets[i].iosock);
+ dnsengine_cares_sockets[i].iosock = NULL;
+ }
+ }
+
+ //register new / update existing sockets
+ for(i = 0; i < ARES_GETSOCK_MAXNUM; i++) {
+ if(!ares_socks[i])
+ break;
+
+ //search matching dnsengine_cares_socket
+ sockid = -1;
+ for(j = 0; j < ARES_GETSOCK_MAXNUM; j++) {
+ if(dnsengine_cares_sockets[j].iosock && dnsengine_cares_sockets[j].iosock->fd == ares_socks[i]) {
+ sockid = j;
+ break;
+ }
+ }
+
+ if(sockid == -1) {
+ //append new socket
+ for(j = 0; j < ARES_GETSOCK_MAXNUM; j++) {
+ if(!dnsengine_cares_sockets[j].iosock) {
+ sockid = j;
+ break;
+ }
+ }
+ if(sockid == -1) {
+ iolog_trigger(IOLOG_ERROR, "Error in dnsengine_cares_update_sockets: could not find free dnsengine_cares_socket in %s:%d", __FILE__, __LINE__);
+ continue;
+ }
+ iosock = _create_socket();
+ if(!iosock)
+ continue;
+
+ //set up iosock
+ iosock->socket_flags |= IOSOCKETFLAG_PARENT_DNSENGINE | IOSOCKETFLAG_OVERRIDE_WANT_RW;
+ iosock->fd = ares_socks[i];
+ dnsengine_cares_sockets[sockid].want_read = 0;
+ dnsengine_cares_sockets[sockid].want_write = 0;
+
+ newsock = 1;
+ } else
+ newsock = 0;
+
+ updatesock = 0;
+ if(dnsengine_cares_sockets[sockid].want_read ^ ARES_GETSOCK_READABLE(sockreqs, i)) {
+ if(ARES_GETSOCK_READABLE(sockreqs, i)) {
+ dnsengine_cares_sockets[sockid].iosock->socket_flags |= IOSOCKETFLAG_OVERRIDE_WANT_R;
+ dnsengine_cares_sockets[sockid].want_read = 1;
+ } else {
+ dnsengine_cares_sockets[sockid].iosock->socket_flags &= ~IOSOCKETFLAG_OVERRIDE_WANT_R;
+ dnsengine_cares_sockets[sockid].want_read = 0;
+ }
+ updatesock = 1;
+ }
+ if(dnsengine_cares_sockets[sockid].want_write ^ ARES_GETSOCK_WRITABLE(sockreqs, i)) {
+ if(ARES_GETSOCK_WRITABLE(sockreqs, i)) {
+ dnsengine_cares_sockets[sockid].iosock->socket_flags |= IOSOCKETFLAG_OVERRIDE_WANT_W;
+ dnsengine_cares_sockets[sockid].want_write = 1;
+ } else {
+ dnsengine_cares_sockets[sockid].iosock->socket_flags &= ~IOSOCKETFLAG_OVERRIDE_WANT_W;
+ dnsengine_cares_sockets[sockid].want_write = 0;
+ }
+ updatesock = 1;
+ }
+ if(updatesock || newsock) {
+ if(newsock)
+ iosocket_activate(dnsengine_cares_sockets[sockid].iosock);
+ else
+ iosocket_update(dnsengine_cares_sockets[sockid].iosock);
+ }
+ }
+}
+
+static void dnsengine_cares_update_timeout() {
+ struct timeval timeout, now;
+ timeout.tv_sec = 60;
+ timeout.tv_usec = 0;
+ ares_timeout(dnsengine_cares_channel, &timeout, &timeout);
+
+ gettimeofday(&now, NULL);
+ timeout.tv_sec += now.tv_sec;
+ timeout.tv_usec += now.tv_usec;
+ if(timeout.tv_usec > 1000000) {
+ timeout.tv_sec += 1;
+ timeout.tv_usec -= 1000000;
+ }
+
+ if(dnsengine_cares_timer)
+ iotimer_set_timeout(dnsengine_cares_timer, &timeout);
+ else {
+ dnsengine_cares_timer = iotimer_create(&timeout);
+ iotimer_set_callback(dnsengine_cares_timer, dnsengine_cares_timer_callback);
+ iotimer_start(dnsengine_cares_timer);
+ }
+}
+
+static IOTIMER_CALLBACK(dnsengine_cares_timer_callback) {
+ dnsengine_cares_timer = NULL;
+ ares_process_fd(dnsengine_cares_channel, ARES_SOCKET_BAD, ARES_SOCKET_BAD);
+ dnsengine_cares_update_timeout();
+ dnsengine_cares_update_sockets();
+}
+
+static void dnsengine_cares_socket_callback(struct _IOSocket *iosock, int wantread, int wantwrite) {
+ int socketfd = iosock->fd;
+ ares_process_fd(dnsengine_cares_channel, (wantread ? socketfd : ARES_SOCKET_BAD), (wantread ? socketfd : ARES_SOCKET_BAD));
+ dnsengine_cares_update_timeout();
+ dnsengine_cares_update_sockets();