| /* |
| * include/types/dns.h |
| * This file provides structures and types for DNS. |
| * |
| * Copyright (C) 2014 Baptiste Assmann <bedis9@gmail.com> |
| * |
| * This library is free software; you can redistribute it and/or |
| * modify it under the terms of the GNU Lesser General Public |
| * License as published by the Free Software Foundation, version 2.1 |
| * exclusively. |
| * |
| * This library 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 |
| * Lesser General Public License for more details. |
| * |
| * You should have received a copy of the GNU Lesser General Public |
| * License along with this library; if not, write to the Free Software |
| * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA |
| */ |
| |
| #ifndef _TYPES_DNS_H |
| #define _TYPES_DNS_H |
| |
| /*DNS maximum values */ |
| /* |
| * Maximum issued from RFC: |
| * RFC 1035: https://www.ietf.org/rfc/rfc1035.txt chapter 2.3.4 |
| * RFC 2671: http://tools.ietf.org/html/rfc2671 |
| */ |
| #define DNS_MAX_LABEL_SIZE 63 |
| #define DNS_MAX_NAME_SIZE 255 |
| #define DNS_MAX_UDP_MESSAGE 4096 |
| |
| /* DNS error messages */ |
| #define DNS_TOO_LONG_FQDN "hostname too long" |
| #define DNS_LABEL_TOO_LONG "one label too long" |
| #define DNS_INVALID_CHARACTER "found an invalid character" |
| |
| /* dns query class */ |
| #define DNS_RCLASS_IN 1 /* internet class */ |
| |
| /* dns record types (non exhaustive list) */ |
| #define DNS_RTYPE_A 1 /* IPv4 address */ |
| #define DNS_RTYPE_CNAME 5 /* canonical name */ |
| #define DNS_RTYPE_AAAA 28 /* IPv6 address */ |
| #define DNS_RTYPE_ANY 255 /* all records */ |
| |
| /* dns rcode values */ |
| #define DNS_RCODE_NO_ERROR 0 /* no error */ |
| #define DNS_RCODE_NX_DOMAIN 3 /* non existent domain */ |
| #define DNS_RCODE_REFUSED 5 /* query refused */ |
| |
| /* DNS request or response header structure */ |
| struct dns_header { |
| unsigned short id:16; /* identifier */ |
| unsigned char rd :1; /* recursion desired 0: no, 1: yes */ |
| unsigned char tc :1; /* truncation 0:no, 1: yes */ |
| unsigned char aa :1; /* authoritative answer 0: no, 1: yes */ |
| unsigned char opcode :4; /* operation code */ |
| unsigned char qr :1; /* query/response 0: query, 1: response */ |
| unsigned char rcode :4; /* response code */ |
| unsigned char z :1; /* no used */ |
| unsigned char ad :1; /* authentic data */ |
| unsigned char cd :1; /* checking disabled */ |
| unsigned char ra :1; /* recursion available 0: no, 1: yes */ |
| unsigned short qdcount :16; /* question count */ |
| unsigned short ancount :16; /* answer count */ |
| unsigned short nscount :16; /* authority count */ |
| unsigned short arcount :16; /* additional count */ |
| }; |
| |
| /* short structure to describe a DNS question */ |
| struct dns_question { |
| unsigned short qtype; /* question type */ |
| unsigned short qclass; /* query class */ |
| }; |
| |
| /* |
| * resolvers section and parameters. It is linked to the name servers |
| * servers points to it. |
| * current resolution are stored in a FIFO list. |
| */ |
| struct dns_resolvers { |
| struct list list; /* resolvers list */ |
| char *id; /* resolvers unique identifier */ |
| struct { |
| const char *file; /* file where the section appears */ |
| int line; /* line where the section appears */ |
| } conf; /* config information */ |
| struct list nameserver_list; /* dns server list */ |
| int count_nameservers; /* total number of nameservers in a resolvers section */ |
| int resolve_retries; /* number of retries before giving up */ |
| struct { /* time to: */ |
| int retry; /* wait for a response before retrying */ |
| } timeout; |
| struct { /* time to hold current data when */ |
| int valid; /* a response is valid */ |
| } hold; |
| struct task *t; /* timeout management */ |
| struct list curr_resolution; /* current running resolutions */ |
| struct eb_root query_ids; /* tree to quickly lookup/retrieve query ids currently in use */ |
| /* used by each nameserver, but stored in resolvers since there must */ |
| /* be a unique relation between an eb_root and an eb_node (resolution) */ |
| }; |
| |
| /* |
| * structure describing a name server used during name resolution. |
| * A name server belongs to a resolvers section. |
| */ |
| struct dns_nameserver { |
| struct list list; /* nameserver chained list */ |
| char *id; /* nameserver unique identifier */ |
| struct { |
| const char *file; /* file where the section appears */ |
| int line; /* line where the section appears */ |
| } conf; /* config information */ |
| struct dns_resolvers *resolvers; |
| struct dgram_conn *dgram; /* transport layer */ |
| struct sockaddr_storage addr; /* IP address */ |
| struct { /* numbers relted to this name server: */ |
| long int sent; /* - queries sent */ |
| long int valid; /* - valid response */ |
| long int update; /* - valid response used to update server's IP */ |
| long int cname; /* - CNAME response requiring new resolution */ |
| long int cname_error; /* - error when resolving CNAMEs */ |
| long int any_err; /* - void response (usually because ANY qtype) */ |
| long int nx; /* - NX response */ |
| long int timeout; /* - queries which reached timeout */ |
| long int refused; /* - queries refused */ |
| long int other; /* - other type of response */ |
| long int invalid; /* - malformed DNS response */ |
| long int too_big; /* - too big response */ |
| long int outdated; /* - outdated response (server slower than the other ones) */ |
| } counters; |
| }; |
| |
| /* |
| * resolution structure associated to single server and used to manage name resolution for |
| * this server. |
| * The only link between the resolution and a nameserver is through the query_id. |
| */ |
| struct dns_resolution { |
| struct list list; /* resolution list */ |
| struct dns_resolvers *resolvers; /* resolvers section associated to this resolution */ |
| void *requester; /* owner of this name resolution */ |
| int (*requester_cb)(struct dns_resolution *, struct dns_nameserver *, unsigned char *, int); |
| /* requester callback for valid response */ |
| int (*requester_error_cb)(struct dns_resolution *, int); |
| /* requester callback, for error management */ |
| char *hostname_dn; /* server hostname in domain name label format */ |
| int hostname_dn_len; /* server domain name label len */ |
| int resolver_family_priority; /* which IP family should the resolver use when both are returned */ |
| time_t last_resolution; /* time of the lastest valid resolution */ |
| time_t last_sent_packet; /* time of the latest DNS packet sent */ |
| time_t last_status_change; /* time of the latest DNS resolution status change */ |
| int query_id; /* DNS query ID dedicated for this resolution */ |
| struct eb32_node qid; /* ebtree query id */ |
| int query_type; /* query type to send. By default DNS_RTYPE_ANY */ |
| int status; /* status of the resolution being processed RSLV_STATUS_* */ |
| int step; /* */ |
| int try; /* current resolution try */ |
| int try_cname; /* number of CNAME requests sent */ |
| int nb_responses; /* count number of responses received */ |
| }; |
| |
| /* last resolution status code */ |
| enum { |
| RSLV_STATUS_NONE = 0, /* no resolution occured yet */ |
| RSLV_STATUS_VALID, /* no error */ |
| RSLV_STATUS_INVALID, /* invalid responses */ |
| RSLV_STATUS_ERROR, /* error */ |
| RSLV_STATUS_NX, /* NXDOMAIN */ |
| RSLV_STATUS_REFUSED, /* server refused our query */ |
| RSLV_STATUS_TIMEOUT, /* no response from DNS servers */ |
| RSLV_STATUS_OTHER, /* other errors */ |
| }; |
| |
| /* current resolution step */ |
| enum { |
| RSLV_STEP_NONE = 0, /* nothing happening currently */ |
| RSLV_STEP_RUNNING, /* resolution is running */ |
| }; |
| |
| /* return codes after analyzing a DNS response */ |
| enum { |
| DNS_RESP_VALID = 0, /* valid response */ |
| DNS_RESP_INVALID, /* invalid response (various type of errors can trigger it) */ |
| DNS_RESP_ERROR, /* DNS error code */ |
| DNS_RESP_NX_DOMAIN, /* resolution unsuccessful */ |
| DNS_RESP_REFUSED, /* DNS server refused to answer */ |
| DNS_RESP_ANCOUNT_ZERO, /* no answers in the response */ |
| DNS_RESP_WRONG_NAME, /* response does not match query name */ |
| DNS_RESP_CNAME_ERROR, /* error when resolving a CNAME in an atomic response */ |
| DNS_RESP_TIMEOUT, /* DNS server has not answered in time */ |
| }; |
| |
| /* return codes after searching an IP in a DNS response buffer, using a family preference */ |
| enum { |
| DNS_UPD_NO = 1, /* provided IP was found and preference is matched |
| * OR provided IP found and preference is not matched, but no IP |
| * matching preference was found */ |
| DNS_UPD_SRVIP_NOT_FOUND, /* provided IP not found |
| * OR provided IP found and preference is not match and an IP |
| * matching preference was found */ |
| DNS_UPD_CNAME, /* CNAME without any IP provided in the response */ |
| DNS_UPD_NAME_ERROR, /* name in the response did not match the query */ |
| }; |
| |
| #endif /* _TYPES_DNS_H */ |