mirror of https://github.com/ipxe/ipxe.git
[dns] Use all configured DNS servers
When no response is obtained from the first configured DNS server, fall back to attempting the other configured servers. Signed-off-by: Michael Brown <mcb30@ipxe.org>pull/121/head
Michael Brown
parent
a95a2eafc5
commit
366206517e
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@ -63,18 +63,33 @@ FEATURE ( FEATURE_PROTOCOL, "DNS", DHCP_EB_FEATURE_DNS, 1 );
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#define EINFO_ENXIO_NO_NAMESERVER \
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__einfo_uniqify ( EINFO_ENXIO, 0x02, "No DNS servers available" )
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/** The DNS server */
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static union {
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struct sockaddr sa;
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struct sockaddr_tcpip st;
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struct sockaddr_in sin;
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struct sockaddr_in6 sin6;
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} nameserver = {
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.st = {
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.st_port = htons ( DNS_PORT ),
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},
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/** A DNS server list */
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struct dns_server {
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/** Server list */
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union {
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/** IPv4 addresses */
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struct in_addr *in;
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/** IPv6 addresses */
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struct in6_addr *in6;
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/** Raw data */
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void *data;
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};
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/** Number of servers */
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unsigned int count;
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};
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/** IPv4 DNS server list */
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static struct dns_server dns4;
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/** IPv6 DNS server list */
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static struct dns_server dns6;
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/** Total number of DNS servers */
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static unsigned int dns_count;
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/** Current DNS server index */
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static unsigned int dns_index;
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/** The DNS search list */
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static struct dns_name dns_search;
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@ -555,6 +570,9 @@ static int dns_question ( struct dns_request *dns ) {
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/* Restore name */
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dns->name.offset = offsetof ( typeof ( dns->buf ), name );
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/* Reset query ID */
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dns->buf.query.id = 0;
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DBGC2 ( dns, "DNS %p question is %s type %s\n", dns,
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dns_name ( &dns->name ), dns_type ( dns->question->qtype ) );
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@ -569,24 +587,54 @@ static int dns_question ( struct dns_request *dns ) {
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*/
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static int dns_send_packet ( struct dns_request *dns ) {
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struct dns_header *query = &dns->buf.query;
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union {
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struct sockaddr sa;
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struct sockaddr_tcpip st;
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struct sockaddr_in sin;
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struct sockaddr_in6 sin6;
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} nameserver;
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struct xfer_metadata meta;
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unsigned int index;
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/* Start retransmission timer */
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start_timer ( &dns->timer );
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/* Generate query identifier */
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query->id = random();
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/* Construct DNS server address */
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memset ( &nameserver, 0, sizeof ( nameserver ) );
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nameserver.st.st_port = htons ( DNS_PORT );
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if ( ! dns_count ) {
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DBGC ( dns, "DNS %p lost DNS servers mid query\n", dns );
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return -EINVAL;
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}
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index = ( dns_index % dns_count );
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if ( index < dns6.count ) {
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nameserver.sin6.sin6_family = AF_INET6;
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memcpy ( &nameserver.sin6.sin6_addr, &dns6.in6[index],
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sizeof ( nameserver.sin6.sin6_addr ) );
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} else {
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nameserver.sin.sin_family = AF_INET;
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nameserver.sin.sin_addr = dns4.in[index - dns6.count];
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}
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/* Construct metadata */
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memset ( &meta, 0, sizeof ( meta ) );
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meta.dest = &nameserver.sa;
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/* Generate query identifier if applicable */
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if ( ! query->id )
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query->id = random();
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/* Send query */
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DBGC ( dns, "DNS %p sending query ID %#04x for %s type %s\n", dns,
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ntohs ( query->id ), dns_name ( &dns->name ),
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dns_type ( dns->question->qtype ) );
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DBGC ( dns, "DNS %p sending %s query ID %#04x for %s type %s\n", dns,
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sock_ntoa ( &nameserver.sa ), ntohs ( query->id ),
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dns_name ( &dns->name ), dns_type ( dns->question->qtype ) );
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/* Send the data */
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return xfer_deliver_raw ( &dns->socket, query, dns->len );
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return xfer_deliver_raw_meta ( &dns->socket, query, dns->len, &meta );
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}
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/**
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* Handle DNS retransmission timer expiry
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* Handle DNS (re)transmission timer expiry
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*
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* @v timer Retry timer
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* @v fail Failure indicator
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@ -595,11 +643,18 @@ static void dns_timer_expired ( struct retry_timer *timer, int fail ) {
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struct dns_request *dns =
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container_of ( timer, struct dns_request, timer );
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/* Terminate DNS request on failure */
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if ( fail ) {
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dns_done ( dns, -ETIMEDOUT );
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} else {
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dns_send_packet ( dns );
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return;
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}
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/* Move to next DNS server if this is a retransmission */
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if ( dns->buf.query.id )
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dns_index++;
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/* Send DNS query */
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dns_send_packet ( dns );
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}
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/**
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@ -927,7 +982,7 @@ static int dns_resolv ( struct interface *resolv,
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int rc;
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/* Fail immediately if no DNS servers */
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if ( ! nameserver.sa.sa_family ) {
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if ( dns_count == 0 ) {
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DBG ( "DNS not attempting to resolve \"%s\": "
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"no DNS servers\n", name );
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rc = -ENXIO_NO_NAMESERVER;
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@ -953,17 +1008,8 @@ static int dns_resolv ( struct interface *resolv,
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memcpy ( dns->search.data, dns_search.data, search_len );
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/* Determine initial query type */
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switch ( nameserver.sa.sa_family ) {
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case AF_INET:
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dns->qtype = htons ( DNS_TYPE_A );
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break;
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case AF_INET6:
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dns->qtype = htons ( DNS_TYPE_AAAA );
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break;
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default:
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rc = -ENOTSUP;
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goto err_type;
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}
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dns->qtype = ( ( dns6.count != 0 ) ?
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htons ( DNS_TYPE_AAAA ) : htons ( DNS_TYPE_A ) );
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/* Construct query */
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query = &dns->buf.query;
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@ -984,7 +1030,7 @@ static int dns_resolv ( struct interface *resolv,
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/* Open UDP connection */
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if ( ( rc = xfer_open_socket ( &dns->socket, SOCK_DGRAM,
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&nameserver.sa, NULL ) ) != 0 ) {
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NULL, NULL ) ) != 0 ) {
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DBGC ( dns, "DNS %p could not open socket: %s\n",
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dns, strerror ( rc ) );
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goto err_open_socket;
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@ -1001,7 +1047,6 @@ static int dns_resolv ( struct interface *resolv,
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err_open_socket:
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err_question:
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err_encode:
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err_type:
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ref_put ( &dns->refcnt );
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err_alloc_dns:
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err_no_nameserver:
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@ -1096,6 +1141,31 @@ const struct setting dnssl_setting __setting ( SETTING_IP_EXTRA, dnssl ) = {
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.type = &setting_type_dnssl,
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};
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/**
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* Apply DNS server addresses
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*
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*/
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static void apply_dns_servers ( void ) {
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int len;
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/* Free existing server addresses */
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free ( dns4.data );
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free ( dns6.data );
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dns4.data = NULL;
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dns6.data = NULL;
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dns4.count = 0;
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dns6.count = 0;
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/* Fetch DNS server addresses */
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len = fetch_raw_setting_copy ( NULL, &dns_setting, &dns4.data );
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if ( len >= 0 )
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dns4.count = ( len / sizeof ( dns4.in[0] ) );
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len = fetch_raw_setting_copy ( NULL, &dns6_setting, &dns6.data );
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if ( len >= 0 )
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dns6.count = ( len / sizeof ( dns6.in6[0] ) );
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dns_count = ( dns4.count + dns6.count );
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}
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/**
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* Apply DNS search list
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*
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@ -1109,8 +1179,7 @@ static void apply_dns_search ( void ) {
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memset ( &dns_search, 0, sizeof ( dns_search ) );
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/* Fetch DNS search list */
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len = fetch_setting_copy ( NULL, &dnssl_setting, NULL, NULL,
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&dns_search.data );
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len = fetch_raw_setting_copy ( NULL, &dnssl_setting, &dns_search.data );
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if ( len >= 0 ) {
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dns_search.len = len;
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return;
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@ -1138,19 +1207,31 @@ static void apply_dns_search ( void ) {
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* @ret rc Return status code
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*/
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static int apply_dns_settings ( void ) {
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void *dbgcol = &dns_count;
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/* Fetch DNS server address */
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nameserver.sa.sa_family = 0;
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if ( fetch_ipv6_setting ( NULL, &dns6_setting,
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&nameserver.sin6.sin6_addr ) >= 0 ) {
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nameserver.sin6.sin6_family = AF_INET6;
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} else if ( fetch_ipv4_setting ( NULL, &dns_setting,
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&nameserver.sin.sin_addr ) >= 0 ) {
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nameserver.sin.sin_family = AF_INET;
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}
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if ( nameserver.sa.sa_family ) {
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DBG ( "DNS using nameserver %s\n",
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sock_ntoa ( &nameserver.sa ) );
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apply_dns_servers();
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if ( DBG_LOG && ( dns_count != 0 ) ) {
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union {
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struct sockaddr sa;
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struct sockaddr_in sin;
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struct sockaddr_in6 sin6;
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} u;
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unsigned int i;
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DBGC ( dbgcol, "DNS servers:" );
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for ( i = 0 ; i < dns6.count ; i++ ) {
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u.sin6.sin6_family = AF_INET6;
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memcpy ( &u.sin6.sin6_addr, &dns6.in6[i],
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sizeof ( u.sin6.sin6_addr ) );
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DBGC ( dbgcol, " %s", sock_ntoa ( &u.sa ) );
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}
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for ( i = 0 ; i < dns4.count ; i++ ) {
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u.sin.sin_family = AF_INET;
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u.sin.sin_addr = dns4.in[i];
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DBGC ( dbgcol, " %s", sock_ntoa ( &u.sa ) );
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}
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DBGC ( dbgcol, "\n" );
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}
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/* Fetch DNS search list */
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@ -1159,16 +1240,16 @@ static int apply_dns_settings ( void ) {
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struct dns_name name;
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int offset;
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DBG ( "DNS search list:" );
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DBGC ( dbgcol, "DNS search list:" );
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memcpy ( &name, &dns_search, sizeof ( name ) );
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while ( name.offset != name.len ) {
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DBG ( " %s", dns_name ( &name ) );
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DBGC ( dbgcol, " %s", dns_name ( &name ) );
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offset = dns_skip_search ( &name );
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if ( offset < 0 )
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break;
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name.offset = offset;
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}
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DBG ( "\n" );
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DBGC ( dbgcol, "\n" );
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}
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return 0;
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