diff options
Diffstat (limited to 'contrib/syslinux/syslinux-4.03/gpxe/src/net/udp/dns.c')
-rw-r--r-- | contrib/syslinux/syslinux-4.03/gpxe/src/net/udp/dns.c | 603 |
1 files changed, 0 insertions, 603 deletions
diff --git a/contrib/syslinux/syslinux-4.03/gpxe/src/net/udp/dns.c b/contrib/syslinux/syslinux-4.03/gpxe/src/net/udp/dns.c deleted file mode 100644 index f94094a..0000000 --- a/contrib/syslinux/syslinux-4.03/gpxe/src/net/udp/dns.c +++ /dev/null @@ -1,603 +0,0 @@ -/* - * Copyright (C) 2006 Michael Brown <mbrown@fensystems.co.uk>. - * - * Portions copyright (C) 2004 Anselm M. Hoffmeister - * <stockholm@users.sourceforge.net>. - * - * This program is free software; you can redistribute it and/or - * modify it under the terms of the GNU General Public License as - * published by the Free Software Foundation; either version 2 of the - * License, or any later version. - * - * This program is distributed in the hope that it will be useful, but - * WITHOUT ANY WARRANTY; without even the implied warranty of - * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU - * General Public License for more details. - * - * You should have received a copy of the GNU General Public License - * along with this program; if not, write to the Free Software - * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. - */ - -FILE_LICENCE ( GPL2_OR_LATER ); - -#include <stdint.h> -#include <stdlib.h> -#include <string.h> -#include <stdio.h> -#include <errno.h> -#include <byteswap.h> -#include <gpxe/refcnt.h> -#include <gpxe/xfer.h> -#include <gpxe/open.h> -#include <gpxe/resolv.h> -#include <gpxe/retry.h> -#include <gpxe/tcpip.h> -#include <gpxe/settings.h> -#include <gpxe/features.h> -#include <gpxe/dns.h> - -/** @file - * - * DNS protocol - * - */ - -FEATURE ( FEATURE_PROTOCOL, "DNS", DHCP_EB_FEATURE_DNS, 1 ); - -/** The DNS server */ -static struct sockaddr_tcpip nameserver = { - .st_port = htons ( DNS_PORT ), -}; - -/** The local domain */ -static char *localdomain; - -/** A DNS request */ -struct dns_request { - /** Reference counter */ - struct refcnt refcnt; - /** Name resolution interface */ - struct resolv_interface resolv; - /** Data transfer interface */ - struct xfer_interface socket; - /** Retry timer */ - struct retry_timer timer; - - /** Socket address to fill in with resolved address */ - struct sockaddr sa; - /** Current query packet */ - struct dns_query query; - /** Location of query info structure within current packet - * - * The query info structure is located immediately after the - * compressed name. - */ - struct dns_query_info *qinfo; - /** Recursion counter */ - unsigned int recursion; -}; - -/** - * Mark DNS request as complete - * - * @v dns DNS request - * @v rc Return status code - */ -static void dns_done ( struct dns_request *dns, int rc ) { - - /* Stop the retry timer */ - stop_timer ( &dns->timer ); - - /* Close data transfer interface */ - xfer_nullify ( &dns->socket ); - xfer_close ( &dns->socket, rc ); - - /* Mark name resolution as complete */ - resolv_done ( &dns->resolv, &dns->sa, rc ); -} - -/** - * Compare DNS reply name against the query name from the original request - * - * @v dns DNS request - * @v reply DNS reply - * @v rname Reply name - * @ret zero Names match - * @ret non-zero Names do not match - */ -static int dns_name_cmp ( struct dns_request *dns, - const struct dns_header *reply, - const char *rname ) { - const char *qname = dns->query.payload; - int i; - - while ( 1 ) { - /* Obtain next section of rname */ - while ( ( *rname ) & 0xc0 ) { - rname = ( ( ( char * ) reply ) + - ( ntohs( *((uint16_t *)rname) ) & ~0xc000 )); - } - /* Check that lengths match */ - if ( *rname != *qname ) - return -1; - /* If length is zero, we have reached the end */ - if ( ! *qname ) - return 0; - /* Check that data matches */ - for ( i = *qname + 1; i > 0 ; i-- ) { - if ( *(rname++) != *(qname++) ) - return -1; - } - } -} - -/** - * Skip over a (possibly compressed) DNS name - * - * @v name DNS name - * @ret name Next DNS name - */ -static const char * dns_skip_name ( const char *name ) { - while ( 1 ) { - if ( ! *name ) { - /* End of name */ - return ( name + 1); - } - if ( *name & 0xc0 ) { - /* Start of a compressed name */ - return ( name + 2 ); - } - /* Uncompressed name portion */ - name += *name + 1; - } -} - -/** - * Find an RR in a reply packet corresponding to our query - * - * @v dns DNS request - * @v reply DNS reply - * @ret rr DNS RR, or NULL if not found - */ -static union dns_rr_info * dns_find_rr ( struct dns_request *dns, - const struct dns_header *reply ) { - int i, cmp; - const char *p = ( ( char * ) reply ) + sizeof ( struct dns_header ); - union dns_rr_info *rr_info; - - /* Skip over the questions section */ - for ( i = ntohs ( reply->qdcount ) ; i > 0 ; i-- ) { - p = dns_skip_name ( p ) + sizeof ( struct dns_query_info ); - } - - /* Process the answers section */ - for ( i = ntohs ( reply->ancount ) ; i > 0 ; i-- ) { - cmp = dns_name_cmp ( dns, reply, p ); - p = dns_skip_name ( p ); - rr_info = ( ( union dns_rr_info * ) p ); - if ( cmp == 0 ) - return rr_info; - p += ( sizeof ( rr_info->common ) + - ntohs ( rr_info->common.rdlength ) ); - } - - return NULL; -} - -/** - * Append DHCP domain name if available and name is not fully qualified - * - * @v string Name as a NUL-terminated string - * @ret fqdn Fully-qualified domain name, malloc'd copy - * - * The caller must free fqdn which is allocated even if the name is already - * fully qualified. - */ -static char * dns_qualify_name ( const char *string ) { - char *fqdn; - - /* Leave unchanged if already fully-qualified or no local domain */ - if ( ( ! localdomain ) || ( strchr ( string, '.' ) != 0 ) ) - return strdup ( string ); - - /* Append local domain to name */ - asprintf ( &fqdn, "%s.%s", string, localdomain ); - return fqdn; -} - -/** - * Convert a standard NUL-terminated string to a DNS name - * - * @v string Name as a NUL-terminated string - * @v buf Buffer in which to place DNS name - * @ret next Byte following constructed DNS name - * - * DNS names consist of "<length>element" pairs. - */ -static char * dns_make_name ( const char *string, char *buf ) { - char *length_byte = buf++; - char c; - - while ( ( c = *(string++) ) ) { - if ( c == '.' ) { - *length_byte = buf - length_byte - 1; - length_byte = buf; - } - *(buf++) = c; - } - *length_byte = buf - length_byte - 1; - *(buf++) = '\0'; - return buf; -} - -/** - * Convert an uncompressed DNS name to a NUL-terminated string - * - * @v name DNS name - * @ret string NUL-terminated string - * - * Produce a printable version of a DNS name. Used only for debugging. - */ -static inline char * dns_unmake_name ( char *name ) { - char *p; - unsigned int len; - - p = name; - while ( ( len = *p ) ) { - *(p++) = '.'; - p += len; - } - - return name + 1; -} - -/** - * Decompress a DNS name - * - * @v reply DNS replay - * @v name DNS name - * @v buf Buffer into which to decompress DNS name - * @ret next Byte following decompressed DNS name - */ -static char * dns_decompress_name ( const struct dns_header *reply, - const char *name, char *buf ) { - int i, len; - - do { - /* Obtain next section of name */ - while ( ( *name ) & 0xc0 ) { - name = ( ( char * ) reply + - ( ntohs ( *((uint16_t *)name) ) & ~0xc000 ) ); - } - /* Copy data */ - len = *name; - for ( i = len + 1 ; i > 0 ; i-- ) { - *(buf++) = *(name++); - } - } while ( len ); - return buf; -} - -/** - * Send next packet in DNS request - * - * @v dns DNS request - */ -static int dns_send_packet ( struct dns_request *dns ) { - static unsigned int qid = 0; - size_t qlen; - - /* Increment query ID */ - dns->query.dns.id = htons ( ++qid ); - - DBGC ( dns, "DNS %p sending query ID %d\n", dns, qid ); - - /* Start retransmission timer */ - start_timer ( &dns->timer ); - - /* Send the data */ - qlen = ( ( ( void * ) dns->qinfo ) - ( ( void * ) &dns->query ) - + sizeof ( dns->qinfo ) ); - return xfer_deliver_raw ( &dns->socket, &dns->query, qlen ); -} - -/** - * Handle DNS retransmission timer expiry - * - * @v timer Retry timer - * @v fail Failure indicator - */ -static void dns_timer_expired ( struct retry_timer *timer, int fail ) { - struct dns_request *dns = - container_of ( timer, struct dns_request, timer ); - - if ( fail ) { - dns_done ( dns, -ETIMEDOUT ); - } else { - dns_send_packet ( dns ); - } -} - -/** - * Receive new data - * - * @v socket UDP socket - * @v data DNS reply - * @v len Length of DNS reply - * @ret rc Return status code - */ -static int dns_xfer_deliver_raw ( struct xfer_interface *socket, - const void *data, size_t len ) { - struct dns_request *dns = - container_of ( socket, struct dns_request, socket ); - const struct dns_header *reply = data; - union dns_rr_info *rr_info; - struct sockaddr_in *sin; - unsigned int qtype = dns->qinfo->qtype; - - /* Sanity check */ - if ( len < sizeof ( *reply ) ) { - DBGC ( dns, "DNS %p received underlength packet length %zd\n", - dns, len ); - return -EINVAL; - } - - /* Check reply ID matches query ID */ - if ( reply->id != dns->query.dns.id ) { - DBGC ( dns, "DNS %p received unexpected reply ID %d " - "(wanted %d)\n", dns, ntohs ( reply->id ), - ntohs ( dns->query.dns.id ) ); - return -EINVAL; - } - - DBGC ( dns, "DNS %p received reply ID %d\n", dns, ntohs ( reply->id )); - - /* Stop the retry timer. After this point, each code path - * must either restart the timer by calling dns_send_packet(), - * or mark the DNS operation as complete by calling - * dns_done() - */ - stop_timer ( &dns->timer ); - - /* Search through response for useful answers. Do this - * multiple times, to take advantage of useful nameservers - * which send us e.g. the CNAME *and* the A record for the - * pointed-to name. - */ - while ( ( rr_info = dns_find_rr ( dns, reply ) ) ) { - switch ( rr_info->common.type ) { - - case htons ( DNS_TYPE_A ): - - /* Found the target A record */ - DBGC ( dns, "DNS %p found address %s\n", - dns, inet_ntoa ( rr_info->a.in_addr ) ); - sin = ( struct sockaddr_in * ) &dns->sa; - sin->sin_family = AF_INET; - sin->sin_addr = rr_info->a.in_addr; - - /* Mark operation as complete */ - dns_done ( dns, 0 ); - return 0; - - case htons ( DNS_TYPE_CNAME ): - - /* Found a CNAME record; update query and recurse */ - DBGC ( dns, "DNS %p found CNAME\n", dns ); - dns->qinfo = ( void * ) dns_decompress_name ( reply, - rr_info->cname.cname, - dns->query.payload ); - dns->qinfo->qtype = htons ( DNS_TYPE_A ); - dns->qinfo->qclass = htons ( DNS_CLASS_IN ); - - /* Terminate the operation if we recurse too far */ - if ( ++dns->recursion > DNS_MAX_CNAME_RECURSION ) { - DBGC ( dns, "DNS %p recursion exceeded\n", - dns ); - dns_done ( dns, -ELOOP ); - return 0; - } - break; - - default: - DBGC ( dns, "DNS %p got unknown record type %d\n", - dns, ntohs ( rr_info->common.type ) ); - break; - } - } - - /* Determine what to do next based on the type of query we - * issued and the reponse we received - */ - switch ( qtype ) { - - case htons ( DNS_TYPE_A ): - /* We asked for an A record and got nothing; - * try the CNAME. - */ - DBGC ( dns, "DNS %p found no A record; trying CNAME\n", dns ); - dns->qinfo->qtype = htons ( DNS_TYPE_CNAME ); - dns_send_packet ( dns ); - return 0; - - case htons ( DNS_TYPE_CNAME ): - /* We asked for a CNAME record. If we got a response - * (i.e. if the next A query is already set up), then - * issue it, otherwise abort. - */ - if ( dns->qinfo->qtype == htons ( DNS_TYPE_A ) ) { - dns_send_packet ( dns ); - return 0; - } else { - DBGC ( dns, "DNS %p found no CNAME record\n", dns ); - dns_done ( dns, -ENXIO ); - return 0; - } - - default: - assert ( 0 ); - dns_done ( dns, -EINVAL ); - return 0; - } -} - -/** - * Receive new data - * - * @v socket UDP socket - * @v rc Reason for close - */ -static void dns_xfer_close ( struct xfer_interface *socket, int rc ) { - struct dns_request *dns = - container_of ( socket, struct dns_request, socket ); - - if ( ! rc ) - rc = -ECONNABORTED; - - dns_done ( dns, rc ); -} - -/** DNS socket operations */ -static struct xfer_interface_operations dns_socket_operations = { - .close = dns_xfer_close, - .vredirect = xfer_vreopen, - .window = unlimited_xfer_window, - .alloc_iob = default_xfer_alloc_iob, - .deliver_iob = xfer_deliver_as_raw, - .deliver_raw = dns_xfer_deliver_raw, -}; - -/** - * Resolve name using DNS - * - * @v resolv Name resolution interface - * @v name Name to resolve - * @v sa Socket address to fill in - * @ret rc Return status code - */ -static int dns_resolv ( struct resolv_interface *resolv, - const char *name, struct sockaddr *sa ) { - struct dns_request *dns; - char *fqdn; - int rc; - - /* Fail immediately if no DNS servers */ - if ( ! nameserver.st_family ) { - DBG ( "DNS not attempting to resolve \"%s\": " - "no DNS servers\n", name ); - rc = -ENXIO; - goto err_no_nameserver; - } - - /* Ensure fully-qualified domain name if DHCP option was given */ - fqdn = dns_qualify_name ( name ); - if ( ! fqdn ) { - rc = -ENOMEM; - goto err_qualify_name; - } - - /* Allocate DNS structure */ - dns = zalloc ( sizeof ( *dns ) ); - if ( ! dns ) { - rc = -ENOMEM; - goto err_alloc_dns; - } - resolv_init ( &dns->resolv, &null_resolv_ops, &dns->refcnt ); - xfer_init ( &dns->socket, &dns_socket_operations, &dns->refcnt ); - dns->timer.expired = dns_timer_expired; - memcpy ( &dns->sa, sa, sizeof ( dns->sa ) ); - - /* Create query */ - dns->query.dns.flags = htons ( DNS_FLAG_QUERY | DNS_FLAG_OPCODE_QUERY | - DNS_FLAG_RD ); - dns->query.dns.qdcount = htons ( 1 ); - dns->qinfo = ( void * ) dns_make_name ( fqdn, dns->query.payload ); - dns->qinfo->qtype = htons ( DNS_TYPE_A ); - dns->qinfo->qclass = htons ( DNS_CLASS_IN ); - - /* Open UDP connection */ - if ( ( rc = xfer_open_socket ( &dns->socket, SOCK_DGRAM, - ( struct sockaddr * ) &nameserver, - NULL ) ) != 0 ) { - DBGC ( dns, "DNS %p could not open socket: %s\n", - dns, strerror ( rc ) ); - goto err_open_socket; - } - - /* Send first DNS packet */ - dns_send_packet ( dns ); - - /* Attach parent interface, mortalise self, and return */ - resolv_plug_plug ( &dns->resolv, resolv ); - ref_put ( &dns->refcnt ); - free ( fqdn ); - return 0; - - err_open_socket: - err_alloc_dns: - ref_put ( &dns->refcnt ); - err_qualify_name: - free ( fqdn ); - err_no_nameserver: - return rc; -} - -/** DNS name resolver */ -struct resolver dns_resolver __resolver ( RESOLV_NORMAL ) = { - .name = "DNS", - .resolv = dns_resolv, -}; - -/****************************************************************************** - * - * Settings - * - ****************************************************************************** - */ - -/** DNS server setting */ -struct setting dns_setting __setting = { - .name = "dns", - .description = "DNS server", - .tag = DHCP_DNS_SERVERS, - .type = &setting_type_ipv4, -}; - -/** Domain name setting */ -struct setting domain_setting __setting = { - .name = "domain", - .description = "Local domain", - .tag = DHCP_DOMAIN_NAME, - .type = &setting_type_string, -}; - -/** - * Apply DNS settings - * - * @ret rc Return status code - */ -static int apply_dns_settings ( void ) { - struct sockaddr_in *sin_nameserver = - ( struct sockaddr_in * ) &nameserver; - int len; - - if ( ( len = fetch_ipv4_setting ( NULL, &dns_setting, - &sin_nameserver->sin_addr ) ) >= 0 ){ - sin_nameserver->sin_family = AF_INET; - DBG ( "DNS using nameserver %s\n", - inet_ntoa ( sin_nameserver->sin_addr ) ); - } - - /* Get local domain DHCP option */ - if ( ( len = fetch_string_setting_copy ( NULL, &domain_setting, - &localdomain ) ) >= 0 ) - DBG ( "DNS local domain %s\n", localdomain ); - - return 0; -} - -/** DNS settings applicator */ -struct settings_applicator dns_applicator __settings_applicator = { - .apply = apply_dns_settings, -}; |