/*
 * $Id$
 *
 * resolver related functions
 *
 * Copyright (C) 2001-2003 FhG Fokus
 *
 * This file is part of ser, a free SIP server.
 *
 * ser 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
 * (at your option) any later version
 *
 * For a license to use the ser software under conditions
 * other than those described here, or to purchase support for this
 * software, please contact iptel.org by e-mail at the following addresses:
 *    info@iptel.org
 *
 * ser 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., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 */
/* History:
 * --------
 *  2003-04-12  support for resolving ipv6 address references added (andrei)
 *  2004-07-28  darwin needs nameser_compat.h (andrei)
 *  2006-07-13  rdata structures put on diet (andrei)
 *  2006-07-17  rdata contains now also the record name (andrei)
 *  2006-08-18  get_record uses flags (andrei)
 *  2006-06-16  naptr support (andrei)
 */



#ifndef __resolve_h
#define __resolve_h

#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <netdb.h>
#include <arpa/nameser.h>
#include <resolv.h>
#include "counters.h"
#include "dns_func.h"

#ifdef __OS_darwin
#include <arpa/nameser_compat.h>
#endif

#include "ip_addr.h"
#ifdef USE_DNS_CACHE
#include "dns_wrappers.h"
#endif


/* define RESOLVE_DBG for debugging info (very noisy) */
#define RESOLVE_DBG
/* define NAPTR_DBG for naptr related debugging info (very noisy) */
#define NAPTR_DBG


#define MAX_QUERY_SIZE 8192
#define ANS_SIZE       8192
#define DNS_HDR_SIZE     12
#define MAX_DNS_NAME 256
#define MAX_DNS_STRING 255

#ifndef T_EBL
/** not official yet - iEnum. */
#define T_EBL 65300
#endif

/* get_record flags */
#define RES_ONLY_TYPE 1   /* return only the specified type records */
#define RES_AR		  2   /* return also the additional records */

/* counter for failed DNS requests
*/
struct dns_counters_h {
    counter_handle_t failed_dns_req;
};

extern struct dns_counters_h dns_cnts_h;
extern struct dns_func_t dns_func;

/* query union*/
union dns_query{
	HEADER hdr;
	unsigned char buff[MAX_QUERY_SIZE];
};


/* rdata struct*/
struct rdata {
	unsigned short type;
	unsigned short pclass;
	unsigned int   ttl;
	void* rdata;
	struct rdata* next;
	unsigned char name_len; /* name length w/o the terminating 0 */
	char name[1]; /* null terminated name (len=name_len+1) */
};
/* real size of the structure */
#define RDATA_SIZE(s) (sizeof(struct rdata)+(s).name_len) /* +1-1 */


/* srv rec. struct*/
struct srv_rdata {
	unsigned short priority;
	unsigned short weight;
	unsigned short port;
	unsigned char name_len; /* name length w/o the terminating 0 */
	char name[1]; /* null terminated name (len=name_len+1) */
};


/* real size of the structure */
#define SRV_RDATA_SIZE(s) (sizeof(struct srv_rdata)+(s).name_len)

/* naptr rec. struct*/
struct naptr_rdata {
	char* flags;    /* points inside str_table */
	char* services; /* points inside str_table */
	char* regexp;   /* points inside str_table */
	char* repl;     /* points inside str_table, null terminated */
	
	unsigned short order;
	unsigned short pref;
	
	unsigned char flags_len;
	unsigned char services_len;
	unsigned char regexp_len;
	unsigned char repl_len; /* not currently used */
	
	char str_table[1]; /* contains all the strings */
};

/* real size of the structure */
#define NAPTR_RDATA_SIZE(s) (sizeof(struct naptr_rdata) \
								+ (s).flags_len \
								+ (s).services_len \
								+ (s).regexp_len \
								+ (s).repl_len + 1 - 1)


/* A rec. struct */
struct a_rdata {
	unsigned char ip[4];
};

struct aaaa_rdata {
	unsigned char ip6[16];
};

/* cname rec. struct*/
struct cname_rdata {
	unsigned char name_len; /* name length w/o the terminating 0 */
	char name[1]; /* null terminated name (len=name_len+1) */
};

/* real size of the structure */
#define CNAME_RDATA_SIZE(s) (sizeof(struct cname_rdata)+(s).name_len)

/* dns character-string */
struct dns_cstr{
	char* cstr; /* pointer to null term. string */
	unsigned char cstr_len;
};

/* txt rec. struct */
struct txt_rdata {
	unsigned short cstr_no; /* number of strings */
	unsigned short tslen; /* total strings table len */
	struct dns_cstr txt[1]; /* at least 1 */
	/* all txt[*].cstr point inside a string table at the end of the struct.*/
};

#define TXT_RDATA_SIZE(s) \
	(sizeof(struct txt_rdata)+((s).cstr_no-1)*sizeof(struct dns_cstr)+\
	 	(s).tslen)

/* ebl rec. struct, see
   http://tools.ietf.org/html/draft-ietf-enum-branch-location-record-03 */
struct ebl_rdata {
	char* separator; /* points inside str_table */
	char* apex;      /* point inside str_table */
	unsigned char separator_len; /* separator len w/o the terminating 0 */
	unsigned char apex_len;      /* apex len w/p the terminating 0 */
	unsigned char position;
	char str_table[1]; /* contains the 2 strings: separator and apex */
};
#define EBL_RDATA_SIZE(s) \
	(sizeof(struct ebl_rdata)-1+(s).separator_len+1+(s).apex_len+1)


struct ptr_rdata {
	unsigned char ptrdname_len; /* name length w/o the terminating 0 */
	char ptrdname[1]; /* null terminated name (len=name_len+1) */
};
/* real size of the structure */
#define PTR_RDATA_SIZE(s) (sizeof(struct ptr_rdata)-1+(s).ptrdname_len+1)


#ifdef HAVE_RESOLV_RES
int match_search_list(const struct __res_state* res, char* name);
#endif
struct rdata* get_record(char* name, int type, int flags);
void free_rdata_list(struct rdata* head);



#define rev_resolvehost(ip)\
					gethostbyaddr((char*)(ip)->u.addr, (ip)->len, (ip)->af)



#define HEX2I(c) \
	(	(((c)>='0') && ((c)<='9'))? (c)-'0' :  \
		(((c)>='A') && ((c)<='F'))? ((c)-'A')+10 : \
		(((c)>='a') && ((c)<='f'))? ((c)-'a')+10 : -1 )





/* converts a str to an ipv4 address, returns the address or 0 on error
   Warning: the result is a pointer to a statically allocated structure */
static inline struct ip_addr* str2ip(str* st)
{
	int i;
	unsigned char *limit;
	static struct ip_addr ip;
	unsigned char* s;

	s=(unsigned char*)st->s;

	/*init*/
	ip.u.addr32[0]=0;
	i=0;
	limit=(unsigned char*)(st->s + st->len);

	for(;s<limit ;s++){
		if (*s=='.'){
				i++;
				if (i>3) goto error_dots;
		}else if ( (*s <= '9' ) && (*s >= '0') ){
				ip.u.addr[i]=ip.u.addr[i]*10+*s-'0';
		}else{
				//error unknown char
				goto error_char;
		}
	}
	if (i<3) goto error_dots;
	ip.af=AF_INET;
	ip.len=4;
	
	return &ip;
error_dots:
#ifdef RESOLVE_DBG
	DBG("str2ip: ERROR: too %s dots in [%.*s]\n", (i>3)?"many":"few", 
			st->len, st->s);
#endif
	return 0;
 error_char:
	/*
	DBG("str2ip: WARNING: unexpected char %c in [%.*s]\n", *s, st->len, st->s);
	*/
	return 0;
}


/* returns an ip_addr struct.; on error returns 0
 * the ip_addr struct is static, so subsequent calls will destroy its content*/
static inline struct ip_addr* str2ip6(str* st)
{
	int i, idx1, rest;
	int no_colons;
	int double_colon;
	int hex;
	static struct ip_addr ip;
	unsigned short* addr_start;
	unsigned short addr_end[8];
	unsigned short* addr;
	unsigned char* limit;
	unsigned char* s;
	
	/* init */
	if ((st->len) && (st->s[0]=='[')){
		/* skip over [ ] */
		if (st->s[st->len-1]!=']') goto error_char;
		s=(unsigned char*)(st->s+1);
		limit=(unsigned char*)(st->s+st->len-1);
	}else{
		s=(unsigned char*)st->s;
		limit=(unsigned char*)(st->s+st->len);
	}
	i=idx1=rest=0;
	double_colon=0;
	no_colons=0;
	ip.af=AF_INET6;
	ip.len=16;
	addr_start=ip.u.addr16;
	addr=addr_start;
	memset(addr_start, 0 , 8*sizeof(unsigned short));
	memset(addr_end, 0 , 8*sizeof(unsigned short));
	for (; s<limit; s++){
		if (*s==':'){
			no_colons++;
			if (no_colons>7) goto error_too_many_colons;
			if (double_colon){
				idx1=i;
				i=0;
				if (addr==addr_end) goto error_colons;
				addr=addr_end;
			}else{
				double_colon=1;
				addr[i]=htons(addr[i]);
				i++;
			}
		}else if ((hex=HEX2I(*s))>=0){
				addr[i]=addr[i]*16+hex;
				double_colon=0;
		}else{
			/* error, unknown char */
			goto error_char;
		}
	}
	if (!double_colon){ /* not ending in ':' */
		addr[i]=htons(addr[i]);
		i++; 
	}
	/* if address contained '::' fix it */
	if (addr==addr_end){
		rest=8-i-idx1;
		memcpy(addr_start+idx1+rest, addr_end, i*sizeof(unsigned short));
	}else{
		/* no double colons inside */
		if (no_colons<7) goto error_too_few_colons;
	}
/*
	DBG("str2ip6: idx1=%d, rest=%d, no_colons=%d, hex=%x\n",
			idx1, rest, no_colons, hex);
	DBG("str2ip6: address %x:%x:%x:%x:%x:%x:%x:%x\n", 
			addr_start[0], addr_start[1], addr_start[2],
			addr_start[3], addr_start[4], addr_start[5],
			addr_start[6], addr_start[7] );
*/
	return &ip;

error_too_many_colons:
#ifdef RESOLVE_DBG
	DBG("str2ip6: ERROR: too many colons in [%.*s]\n", st->len, st->s);
#endif
	return 0;

error_too_few_colons:
#ifdef RESOLVE_DBG
	DBG("str2ip6: ERROR: too few colons in [%.*s]\n", st->len, st->s);
#endif
	return 0;

error_colons:
#ifdef RESOLVE_DBG
	DBG("str2ip6: ERROR: too many double colons in [%.*s]\n", st->len, st->s);
#endif
	return 0;

error_char:
	/*
	DBG("str2ip6: WARNING: unexpected char %c in  [%.*s]\n", *s, st->len,
			st->s);*/
	return 0;
}



struct hostent* _sip_resolvehost(str* name, unsigned short* port, char* proto);



/* gethostbyname wrapper, handles ip/ipv6 automatically */
static inline struct hostent* _resolvehost(char* name)
{
	static struct hostent* he=0;
#ifdef HAVE_GETIPNODEBYNAME 
	int err;
	static struct hostent* he2=0;
#endif
#ifndef DNS_IP_HACK
	int len;
#endif
#ifdef DNS_IP_HACK
	struct ip_addr* ip;
	str s;

	s.s = (char*)name;
	s.len = strlen(name);

	/* check if it's an ip address */
	if ( ((ip=str2ip(&s))!=0)
		  || ((ip=str2ip6(&s))!=0)
		){
		/* we are lucky, this is an ip address */
		return ip_addr2he(&s, ip);
	}
	
#else /* DNS_IP_HACK */
	len=0;
	if (*name=='['){
		len=strlen(name);
		if (len && (name[len-1]==']')){
			name[len-1]=0; /* remove '[' */
			name++; /* skip '[' */
			goto skip_ipv4;
		}
	}
#endif
	/* ipv4 */
	he=dns_func.sr_gethostbyname(name);

	if(he==0 && cfg_get(core, core_cfg, dns_try_ipv6)){
#ifndef DNS_IP_HACK
skip_ipv4:
#endif
		/*try ipv6*/
	#ifdef HAVE_GETHOSTBYNAME2
		he=dns_func.sr_gethostbyname2(name, AF_INET6);
	#elif defined HAVE_GETIPNODEBYNAME
		/* on solaris 8 getipnodebyname has a memory leak,
		 * after some time calls to it will fail with err=3
		 * solution: patch your solaris 8 installation */
		if (he2) freehostent(he2);
		he=he2=getipnodebyname(name, AF_INET6, 0, &err);
	#else
		#error neither gethostbyname2 or getipnodebyname present
	#endif
#ifndef DNS_IP_HACK
		if (len) name[len-2]=']'; /* restore */
#endif
	}
	return he;
}


int resolv_init(void);

/* callback/fixup functions executed by the configuration framework */
void resolv_reinit(str *gname, str *name);
int dns_reinit_fixup(void *handle, str *gname, str *name, void **val);
int dns_try_ipv6_fixup(void *handle, str *gname, str *name, void **val);
void reinit_naptr_proto_prefs(str *gname, str *name);

#ifdef DNS_WATCHDOG_SUPPORT
/* callback function that is called by the child processes
 * when they reinitialize the resolver
 *
 * Note, that this callback is called by each chiled process separately!!!
 * If the callback is registered after forking, only the child process
 * that installs the hook will call the callback.
 */
typedef void (*on_resolv_reinit)(str*);
int register_resolv_reinit_cb(on_resolv_reinit cb);
#endif


int sip_hostport2su(union sockaddr_union* su, str* host, unsigned short port,
						char* proto);



/* wrappers */
#ifdef USE_DNS_CACHE
#define resolvehost dns_resolvehost
#define sip_resolvehost dns_sip_resolvehost
#else
#define resolvehost _resolvehost
#define sip_resolvehost _sip_resolvehost
#endif



#ifdef USE_NAPTR
/* NAPTR helper functions */
typedef unsigned int naptr_bmp_t; /* type used for keeping track of tried
									 naptr records*/
#define MAX_NAPTR_RRS (sizeof(naptr_bmp_t)*8)

/* use before first call to naptr_sip_iterate */
#define naptr_iterate_init(bmp) \
	do{ \
		*(bmp)=0; \
	}while(0) \

struct rdata* naptr_sip_iterate(struct rdata* naptr_head, 
										naptr_bmp_t* tried,
										str* srv_name, char* proto);
/* returns sip proto if valis sip naptr record, .-1 otherwise */
char naptr_get_sip_proto(struct naptr_rdata* n);
/* returns true if new_proto is preferred over old_proto */
int naptr_proto_preferred(char new_proto, char old_proto);
/* returns true if we support the protocol */
int naptr_proto_supported(char proto);
/* choose between 2 naptr records, should take into account local
 * preferences too
 * returns 1 if the new record was selected, 0 otherwise */
int naptr_choose (struct naptr_rdata** crt, char* crt_proto,
									struct naptr_rdata* n , char n_proto);

#endif/* USE_NAPTR */

struct hostent* no_naptr_srv_sip_resolvehost(str* name, unsigned short* port,
		char* proto);

#endif