dns.h

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/*
 *  Revision 20231219, Erwin Hoffmann
 *  - MSGSIZE 1232 byte according to DNS Flag Day recommendation
 *  - Added additional return codes
 *  Revision 20210908, Erwin Hoffmann
 *  - included MINMSGSIZE, MAXMSGSIZE 
 *  - included TCP_BACKLOG 
 *  Revision 20210829, Erwin Hoffmann
 *  - added randombind4 for dns_transmit.c
 *  Revision 20180606, Erwin Hoffmann
 *  - struct dns_transmit is now curve-enabled
 *  Revision 20180222, Erwin Hoffmann
 *  - we consider in total 32 NS IPs (IPv4 + IPv6)
 *  - added dns_transmit_start6
 *  - added uint32 scope_ids[32], 
 *    the initial NS scopes read from /etc/resolv.conf et al.
 *  Revision 20180118, Erwin Hoffmann
 *  - included MSGSIZE for DNS messages (instead of MTUSIZE)
*/
#ifndef DNS_H
#define DNS_H
 
#include "stralloc.h"
#include "iopause.h"
#include "taia.h"
#include "ip.h"
 
/* Note: The conventions are subject of change in forthcoming versions */
 
#define DNS_NXD   0             /* NXDOMAIN,␣NODATA␣*/
#define DNS_MEM  -1             /* out of memory; fatal */
#define DNS_ERR  -2             /* parsing errors and others */
#define DNS_COM  -3             /* (socket) communication errors - SERVFAIL */
#define DNS_INT  -4             /* internal errors */
#define DNS_SOFT -5             /* DNS_ERR␣or␣DNS_COM␣*/$
#define DNS_HARD -6             /* DNS␣loop␣problem␣*/$
 
#define MSGSIZE MTUSIZE - 48    /* DNS Flag Day 2020 recommendation */
#define MINMSGSIZE 512          /* RFC 1035 */
#define MAXMSGSIZE 4096         /* 4069 seen with EDNS0 */ 
#define MAXSEGMENT 65535        /* Max TCP buffer size */
#define MAX_TTL 655360          /* Default TTL for static DNS objects */        
 
#define QUERY_MAXNS 32          /* 16 IPv4 + 16 IPv6 NS */
#define QUERY_MAXIPLEN 512      /* QUERY_MAXNS * 16 */
#define TCP_BACKLOG 20          /* the number of TCP connections supported simultaneously */
#define FQDN_LEN 255            /* length of FQDN including all labels + dots */
 
#define EDNS0FLAG 1
 
/* Note: These following definitions are subject of change */
 
#define DNS_C_IN "\0\1"
#define DNS_C_ANY "\0\377"
 
#define DNS_T_A "\0\1"
#define DNS_T_NS "\0\2"
#define DNS_T_CNAME "\0\5"
#define DNS_T_SOA "\0\6"
#define DNS_T_PTR "\0\14"
#define DNS_T_HINFO "\0\15"
#define DNS_T_MX "\0\17"
#define DNS_T_TXT "\0\20"
#define DNS_T_RP "\0\21"
#define DNS_T_SIG "\0\30"
#define DNS_T_KEY "\0\31"
#define DNS_T_AAAA "\0\34"
#define DNS_T_SRV "\0\41"
#define DNS_T_NAPTR "\0\43"
#define DNS_T_CERT "\0\45"
#define DNS_T_OPT "\0\51"
#define DNS_T_DS "\0\53"
#define DNS_T_SSHFP "\0\54"
#define DNS_T_IPSECKEY "\0\55"
#define DNS_T_RRSIG "\0\56"
#define DNS_T_NSEC "\0\57"
#define DNS_T_DNSKEY "\0\60"
#define DNS_T_NSEC3 "\0\62"
#define DNS_T_NSEC3PARAM "\0\63"
#define DNS_T_TLSA "\0\64"
#define DNS_T_HIP "\0\67"
#define DNS_T_OPENPGPKEY "\0\75"
#define DNS_T_SPF "\0\143"
#define DNS_T_AXFR "\0\374"
#define DNS_T_ANY "\0\377"
#define DNS_T_CAA "\1\1"
 
#define LOCALHOST "localhost" /* no clear distinction IPv4/IPv6 */
#define IP4_LOOPBACK "ip4-loopback"
#define IP6_LOOPBACK "ip6-loopback"
 
struct dns_transmit {
  char *query;  /* 0, or dynamically allocated */
  unsigned int querylen;
  char *packet; /* 0, or dynamically allocated */
  unsigned int packetlen;
  int s1;       /* 0, or 1 + an open file descriptor */
  int tcpstate;
  int flagrecursive;
  unsigned int udploop;
  unsigned int curserver;
  struct taia deadline;
  unsigned int pos;
  const char *name;    /* query name */
  const char *servers;
  const char *keys;
  const char *pubkey;
  const char *suffix;  /* domain name */
  char nonce[12];
  uint32 scope_id;
  char localip[16];
  char qtype[2];
} ;
 
/* General */
 
extern void dns_random_init(const char *);
extern unsigned int dns_random(unsigned int);
 
extern void dns_domain_free(char **);
extern int dns_domain_copy(char **,const char *);
extern unsigned int dns_domain_length(const char *);
extern int dns_domain_equal(const char *,const char *);
extern int dns_domain_suffix(const char *,const char *);
extern unsigned int dns_domain_suffixpos(const char *,const char *);
extern int dns_domain_fromdot(char **,const char *,unsigned int);
extern int dns_domain_todot_cat(stralloc *,const char *);
 
extern unsigned int dns_packet_copy(const char *,unsigned int,unsigned int,char *,unsigned int);
extern unsigned int dns_packet_getname(const char *,unsigned int,unsigned int,char **);
extern unsigned int dns_packet_skipname(const char *,unsigned int,unsigned int);
 
extern struct dns_transmit dns_resolve_tx;
extern int dns_transmit_start(struct dns_transmit *,const char *,int,const char *,const char *,const char *);
extern void dns_transmit_free(struct dns_transmit *);
extern void dns_transmit_io(struct dns_transmit *,iopause_fd *,struct taia *);
extern int dns_transmit_get(struct dns_transmit *,const iopause_fd *,const struct taia *);
 
/* Common IPv4 + IPv6 */
 
extern int dns_resolvconfip(char *,uint32 *);
extern int dns_resolvconfrewrite(stralloc *);
extern int dns_resolve(const char *,const char *);
 
extern int dns_name(stralloc *,const char *);
extern int dns_name_packet(stralloc *,const char *,unsigned int);
extern int dns_txt_packet(stralloc *,const char *,unsigned int);
extern int dns_txt(stralloc *,const stralloc *);
extern int dns_mx_packet(stralloc *,const char *,unsigned int);
extern int dns_mx(stralloc *,const stralloc *);
extern int dns_ip_qualify(stralloc *,stralloc *,const stralloc *);
 
/* IPv4 specific */
 
extern int dns_ip4_packet(stralloc *,const char *,unsigned int);
extern int dns_ip4(stralloc *,stralloc *);
extern void dns_sortip4(char *,unsigned int);
 
extern int dns_ip4_qualify_rules(stralloc *,stralloc *,const stralloc *,const stralloc *);
extern int dns_ip4_qualify(stralloc *,stralloc *,const stralloc *);
 
#define DNS_NAME4_DOMAIN 31
extern int dns_name4_domain(char *,const char *);
extern int dns_name4(stralloc *,const char *);
 
/* IPv6 specific */
 
extern int dns_ip6_packet(stralloc *,const char *,unsigned int);
extern int dns_ip6(stralloc *,stralloc *);
extern void dns_sortip6(char *,unsigned int);
 
extern int dns_ip6_qualify_rules(stralloc *,stralloc *,const stralloc *,const stralloc *);
extern int dns_ip6_qualify(stralloc *,stralloc *,const stralloc *);
 
#define DNS_NAME6_DOMAIN (4*16+11)
extern int dns_name6_domain(char *,const char *);
extern int dns_name6(stralloc *,const char *);
 
extern int dns_transmit_start6(struct dns_transmit *,const char *,int,const char *,const char *,const char *,const uint32 *);
 
extern unsigned int dns_packet_edns0(const char *,const char *,const int,unsigned int);
 
/* General */
 
extern void socketfree(struct dns_transmit *);
extern void queryfree(struct dns_transmit *);
extern void packetfree(struct dns_transmit *);
extern int randombind(struct dns_transmit *);
extern int randombind4(struct dns_transmit *);
extern int serverwantstcp(const char *,unsigned int);
extern int serverfailed(const char *,unsigned int,char *);
extern int getscopeid(const struct dns_transmit *,const char *);
extern int firstudp(struct dns_transmit *);
extern int nextudp(struct dns_transmit *);
extern int firsttcp(struct dns_transmit *);
extern int nexttcp(struct dns_transmit *);
 
#endif