/* Initialise the resolver. Open a socket and bind it to the address
of the server. return -1 if something goes wrong, otherwise 0. If
we are being called a second time we have to be careful to allow
any ongoing lookups to finish before we close the socket and
connect to a different DNS server. The danger here is that we may
have to wait for upto 32 seconds if the DNS server is down.
*/
int
cyg_dns_res_init(struct in_addr *dns_server)
{
struct sockaddr_in server;
struct servent *sent;
static int init =0;
CYG_REPORT_FUNCNAMETYPE( "cyg_dns_res_init", "returning %d" );
CYG_REPORT_FUNCARG1( "dns_server=%08x", dns_server );
CYG_CHECK_DATA_PTR( dns_server, "dns_server is not a valid pointer!" );
if (init) {
cyg_drv_mutex_lock(&dns_mutex);
cyg_thread_free_data_index(ptdindex);
if (s >= 0) {
close(s);
}
} else {
init = 1;
cyg_drv_mutex_init(&dns_mutex);
cyg_drv_mutex_lock(&dns_mutex);
}
s = socket(PF_INET, SOCK_DGRAM, 0);
if (s < 0) {
cyg_drv_mutex_unlock(&dns_mutex);
CYG_REPORT_RETVAL( -1 );
return -1;
}
sent = getservbyname("domain", "udp");
if (sent == (struct servent *)0) {
s = -1;
cyg_drv_mutex_unlock(&dns_mutex);
CYG_REPORT_RETVAL( -1 );
return -1;
}
memcpy((char *)&server.sin_addr, (const void *)dns_server, sizeof(server.sin_addr));
server.sin_port = sent->s_port;
server.sin_family = AF_INET;
server.sin_len = sizeof(server);
if (connect(s, (struct sockaddr *)&server, sizeof(server)) < 0) {
s = -1;
cyg_drv_mutex_unlock(&dns_mutex);
CYG_REPORT_RETVAL( -1 );
return -1;
}
ptdindex = cyg_thread_new_data_index();
cyg_drv_mutex_unlock(&dns_mutex);
CYG_REPORT_RETVAL( 0 );
return 0;
}
int
matherr( struct exception *x )
{
CYG_REPORT_FUNCNAMETYPE( "matherr", "returning %d" );
CYG_UNUSED_PARAM( struct exception *, x );
CYG_EMPTY_STATEMENT;
CYG_REPORT_RETVAL( 0 );
return 0;
} // matherr()
/* Send the query to the server and read the response back. Return -1
if it fails, otherwise put the response back in msg and return the
length of the response. */
static int
send_recv(char * msg, int len, int msglen)
{
struct dns_header *dns_hdr;
struct timeval timeout;
int finished = false;
int backoff = 2;
fd_set readfds;
int written;
int ret;
CYG_REPORT_FUNCNAMETYPE( "send_recv", "returning %d" );
CYG_REPORT_FUNCARG3( "msg=%08x, len=%d, msglen", msg, len, msglen );
CYG_CHECK_DATA_PTR( msg, "msg is not a valid pointer!" );
dns_hdr = (struct dns_header *) msg;
do {
written = write(s, msg, len);
if (written < 0 || (written!=len)) {
ret = -1;
break;
}
FD_ZERO(&readfds);
FD_SET(s, &readfds);
timeout.tv_sec = backoff;
timeout.tv_usec = 0;
backoff = backoff << 1;
ret = select(s+1, &readfds, NULL, NULL, &timeout);
if (ret < 0) {
ret = -1;
break;
}
/* Timeout */
if (ret == 0) {
if (backoff > 16) {
h_errno = TRY_AGAIN;
ret = -1;
break;
}
}
if (ret == 1) {
ret = read(s, msg, msglen);
if (ret < 0) {
ret = -1;
break;
}
/* Reply to an old query. Ignore it */
if (ntohs(dns_hdr->id) != (id-1)) {
continue;
}
finished = true;
}
} while (!finished);
CYG_REPORT_RETVAL( ret );
return ret;
}
