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https://github.com/haproxy/haproxy.git
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987e16d6f4
This adds new "hold" timers : nx, refused, timeout, other. This timers will be used to tell HAProxy to keep an erroneous response as valid for the corresponding period. For now they're only configured, not enforced.
288 lines
11 KiB
C
288 lines
11 KiB
C
/*
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* include/types/dns.h
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* This file provides structures and types for DNS.
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*
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* Copyright (C) 2014 Baptiste Assmann <bedis9@gmail.com>
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*
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* This library is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Lesser General Public
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* License as published by the Free Software Foundation, version 2.1
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* exclusively.
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*
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* This library is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public
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* License along with this library; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
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*/
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#ifndef _TYPES_DNS_H
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#define _TYPES_DNS_H
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/*DNS maximum values */
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/*
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* Maximum issued from RFC:
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* RFC 1035: https://www.ietf.org/rfc/rfc1035.txt chapter 2.3.4
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* RFC 2671: http://tools.ietf.org/html/rfc2671
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*/
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#define DNS_MAX_LABEL_SIZE 63
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#define DNS_MAX_NAME_SIZE 255
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#define DNS_MAX_UDP_MESSAGE 512
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/* DNS minimun record size: 1 char + 1 NULL + type + class */
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#define DNS_MIN_RECORD_SIZE ( 1 + 1 + 2 + 2 )
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/* maximum number of query records in a DNS response
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* For now, we allow only one */
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#define DNS_MAX_QUERY_RECORDS 1
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/* maximum number of answer record in a DNS response */
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#define DNS_MAX_ANSWER_RECORDS ((DNS_MAX_UDP_MESSAGE - DNS_HEADER_SIZE) / DNS_MIN_RECORD_SIZE)
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/* size of dns_buffer used to store responses from the buffer
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* dns_buffer is used to store data collected from records found in a response.
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* Before using it, caller will always check that there is at least DNS_MAX_NAME_SIZE bytes
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* available */
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#define DNS_ANALYZE_BUFFER_SIZE DNS_MAX_UDP_MESSAGE + DNS_MAX_NAME_SIZE
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/* DNS error messages */
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#define DNS_TOO_LONG_FQDN "hostname too long"
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#define DNS_LABEL_TOO_LONG "one label too long"
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#define DNS_INVALID_CHARACTER "found an invalid character"
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/* dns query class */
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#define DNS_RCLASS_IN 1 /* internet class */
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/* dns record types (non exhaustive list) */
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#define DNS_RTYPE_A 1 /* IPv4 address */
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#define DNS_RTYPE_CNAME 5 /* canonical name */
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#define DNS_RTYPE_AAAA 28 /* IPv6 address */
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#define DNS_RTYPE_ANY 255 /* all records */
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/* dns rcode values */
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#define DNS_RCODE_NO_ERROR 0 /* no error */
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#define DNS_RCODE_NX_DOMAIN 3 /* non existent domain */
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#define DNS_RCODE_REFUSED 5 /* query refused */
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/* dns flags masks */
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#define DNS_FLAG_TRUNCATED 0x0200 /* mask for truncated flag */
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#define DNS_FLAG_REPLYCODE 0x000F /* mask for reply code */
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/* max number of network preference entries are avalaible from the
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* configuration file.
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*/
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#define SRV_MAX_PREF_NET 5
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/* DNS header size */
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#define DNS_HEADER_SIZE sizeof(struct dns_header)
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/* DNS request or response header structure */
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struct dns_header {
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uint16_t id;
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uint16_t flags;
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uint16_t qdcount;
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uint16_t ancount;
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uint16_t nscount;
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uint16_t arcount;
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} __attribute__ ((packed));
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/* short structure to describe a DNS question */
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/* NOTE: big endian structure */
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struct dns_question {
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unsigned short qtype; /* question type */
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unsigned short qclass; /* query class */
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};
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/* NOTE: big endian structure */
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struct dns_query_item {
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struct list list;
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char name[DNS_MAX_NAME_SIZE]; /* query name */
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unsigned short type; /* question type */
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unsigned short class; /* query class */
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};
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/* NOTE: big endian structure */
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struct dns_answer_item {
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struct list list;
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char *name; /* answer name
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* For SRV type, name also includes service
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* and protocol value */
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int16_t type; /* question type */
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int16_t class; /* query class */
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int32_t ttl; /* response TTL */
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int16_t priority; /* SRV type priority */
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int16_t weight; /* SRV type weight */
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int16_t port; /* SRV type port */
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int16_t data_len; /* number of bytes in target below */
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struct sockaddr address; /* IPv4 or IPv6, network format */
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char *target; /* Response data: SRV or CNAME type target */
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};
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struct dns_response_packet {
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struct dns_header header;
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struct list query_list;
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struct list answer_list;
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/* authority and additional_information ignored for now */
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};
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/*
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* resolvers section and parameters. It is linked to the name servers
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* servers points to it.
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* current resolution are stored in a FIFO list.
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*/
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struct dns_resolvers {
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struct list list; /* resolvers list */
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char *id; /* resolvers unique identifier */
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struct {
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const char *file; /* file where the section appears */
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int line; /* line where the section appears */
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} conf; /* config information */
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struct list nameserver_list; /* dns server list */
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int count_nameservers; /* total number of nameservers in a resolvers section */
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int resolve_retries; /* number of retries before giving up */
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struct { /* time to: */
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int retry; /* wait for a response before retrying */
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} timeout;
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struct { /* time to hold current data when */
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int valid; /* a response is valid */
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int nx; /* a response doesn't exist */
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int timeout; /* no answer was delivered */
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int refused; /* dns server refused to answer */
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int other; /* other dns response errors */
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} hold;
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struct task *t; /* timeout management */
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struct list curr_resolution; /* current running resolutions */
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struct eb_root query_ids; /* tree to quickly lookup/retrieve query ids currently in use */
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/* used by each nameserver, but stored in resolvers since there must */
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/* be a unique relation between an eb_root and an eb_node (resolution) */
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};
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/*
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* structure describing a name server used during name resolution.
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* A name server belongs to a resolvers section.
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*/
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struct dns_nameserver {
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struct list list; /* nameserver chained list */
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char *id; /* nameserver unique identifier */
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struct {
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const char *file; /* file where the section appears */
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int line; /* line where the section appears */
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} conf; /* config information */
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struct dns_resolvers *resolvers;
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struct dgram_conn *dgram; /* transport layer */
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struct sockaddr_storage addr; /* IP address */
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struct { /* numbers relted to this name server: */
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long int sent; /* - queries sent */
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long int valid; /* - valid response */
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long int update; /* - valid response used to update server's IP */
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long int cname; /* - CNAME response requiring new resolution */
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long int cname_error; /* - error when resolving CNAMEs */
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long int any_err; /* - void response (usually because ANY qtype) */
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long int nx; /* - NX response */
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long int timeout; /* - queries which reached timeout */
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long int refused; /* - queries refused */
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long int other; /* - other type of response */
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long int invalid; /* - malformed DNS response */
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long int too_big; /* - too big response */
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long int outdated; /* - outdated response (server slower than the other ones) */
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long int truncated; /* - truncated response */
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} counters;
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};
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struct dns_options {
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int family_prio; /* which IP family should the resolver use when both are returned */
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struct {
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int family;
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union {
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struct in_addr in4;
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struct in6_addr in6;
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} addr;
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union {
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struct in_addr in4;
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struct in6_addr in6;
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} mask;
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} pref_net[SRV_MAX_PREF_NET];
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int pref_net_nb; /* The number of registered prefered networks. */
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};
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/*
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* resolution structure associated to single server and used to manage name resolution for
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* this server.
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* The only link between the resolution and a nameserver is through the query_id.
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*/
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struct dns_resolution {
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struct list list; /* resolution list */
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struct dns_resolvers *resolvers; /* resolvers section associated to this resolution */
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void *requester; /* owner of this name resolution */
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int (*requester_cb)(struct dns_resolution *, struct dns_nameserver *, struct dns_response_packet *);
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/* requester callback for valid response */
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int (*requester_error_cb)(struct dns_resolution *, int);
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/* requester callback, for error management */
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char *hostname_dn; /* server hostname in domain name label format */
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int hostname_dn_len; /* server domain name label len */
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struct dns_options *opts; /* IP selection options inherited from the configuration file. */
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unsigned int last_resolution; /* time of the lastest valid resolution */
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unsigned int last_sent_packet; /* time of the latest DNS packet sent */
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unsigned int last_status_change; /* time of the latest DNS resolution status change */
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int query_id; /* DNS query ID dedicated for this resolution */
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struct eb32_node qid; /* ebtree query id */
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int query_type;
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/* query type to send. By default DNS_RTYPE_A or DNS_RTYPE_AAAA depending on resolver_family_priority */
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int status; /* status of the resolution being processed RSLV_STATUS_* */
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int step; /* */
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int try; /* current resolution try */
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int try_cname; /* number of CNAME requests sent */
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int nb_responses; /* count number of responses received */
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};
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/* last resolution status code */
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enum {
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RSLV_STATUS_NONE = 0, /* no resolution occured yet */
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RSLV_STATUS_VALID, /* no error */
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RSLV_STATUS_INVALID, /* invalid responses */
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RSLV_STATUS_ERROR, /* error */
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RSLV_STATUS_NX, /* NXDOMAIN */
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RSLV_STATUS_REFUSED, /* server refused our query */
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RSLV_STATUS_TIMEOUT, /* no response from DNS servers */
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RSLV_STATUS_OTHER, /* other errors */
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};
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/* current resolution step */
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enum {
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RSLV_STEP_NONE = 0, /* nothing happening currently */
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RSLV_STEP_RUNNING, /* resolution is running */
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};
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/* return codes after analyzing a DNS response */
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enum {
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DNS_RESP_VALID = 0, /* valid response */
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DNS_RESP_INVALID, /* invalid response (various type of errors can trigger it) */
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DNS_RESP_ERROR, /* DNS error code */
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DNS_RESP_NX_DOMAIN, /* resolution unsuccessful */
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DNS_RESP_REFUSED, /* DNS server refused to answer */
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DNS_RESP_ANCOUNT_ZERO, /* no answers in the response */
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DNS_RESP_WRONG_NAME, /* response does not match query name */
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DNS_RESP_CNAME_ERROR, /* error when resolving a CNAME in an atomic response */
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DNS_RESP_TIMEOUT, /* DNS server has not answered in time */
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DNS_RESP_TRUNCATED, /* DNS response is truncated */
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DNS_RESP_NO_EXPECTED_RECORD, /* No expected records were found in the response */
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DNS_RESP_QUERY_COUNT_ERROR, /* we did not get the expected number of queries in the response */
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};
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/* return codes after searching an IP in a DNS response buffer, using a family preference */
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enum {
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DNS_UPD_NO = 1, /* provided IP was found and preference is matched
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* OR provided IP found and preference is not matched, but no IP
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* matching preference was found */
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DNS_UPD_SRVIP_NOT_FOUND, /* provided IP not found
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* OR provided IP found and preference is not match and an IP
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* matching preference was found */
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DNS_UPD_CNAME, /* CNAME without any IP provided in the response */
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DNS_UPD_NAME_ERROR, /* name in the response did not match the query */
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DNS_UPD_NO_IP_FOUND, /* no IP could be found in the response */
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};
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#endif /* _TYPES_DNS_H */
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