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/*
dns.h - dns library declarations based on firedns Copyright (C) 2002 Ian Gulliver
This program is free software; you can redistribute it and/or modify
it under the terms of version 2 of the GNU General Public License as
published by the Free Software Foundation.
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., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*/
#ifndef _DNS_H
#define _DNS_H
#include <string>
#include "inspircd_config.h"
#include "socket.h"
#include "base.h"
struct dns_ip4list
{
in_addr ip;
dns_ip4list *next;
};
/**
* Error types that class Resolver can emit to its error method.
*/
enum ResolverError
{
RESOLVER_NOERROR = 0,
RESOLVER_NSDOWN = 1,
RESOLVER_NXDOMAIN = 2,
RESOLVER_NOTREADY = 3
};
/** The DNS class allows fast nonblocking resolution of hostnames
* and ip addresses. It is based heavily upon firedns by Ian Gulliver.
* Modules SHOULD avoid using this class to resolve hostnames and IP
* addresses, as it is a low-level wrapper around the UDP socket routines
* and is probably not abstracted enough for real use. Please see the
* Resolver class if you wish to resolve hostnames.
*/
class DNS : public Extensible
{
private:
in_addr *binip;
char* result;
char localbuf[1024];
int t;
void dns_init();
int myfd;
void dns_init_2(const char* dnsserver);
in_addr *dns_aton4(const char * const ipstring);
char *dns_ntoa4(const in_addr * const ip);
int dns_getip4(const char * const name);
int dns_getip4list(const char * const name);
int dns_getname4(const in_addr * const ip);
char *dns_getresult(const int fd);
in_addr *dns_aton4_s(const char * const ipstring, in_addr * const ip);
char *dns_ntoa4_s(const in_addr * const ip, char * const result);
char *dns_getresult_s(const int fd, char * const result);
in_addr *dns_aton4_r(const char * const ipstring);
char *dns_ntoa4_r(const in_addr * const ip);
char *dns_getresult_r(const int fd);
public:
/** The default constructor uses dns addresses read from /etc/resolv.conf.
* Please note that it will re-read /etc/resolv.conf for each copy of the
* class you instantiate, causing disk access and slow lookups if you create
* a lot of them. Consider passing the constructor a server address as a parameter
* instead.
*/
DNS();
/** This constructor accepts a dns server address. The address must be in dotted
* decimal form, e.g. 1.2.3.4.
*/
DNS(const std::string &dnsserver);
/** The destructor frees all used structures.
*/
~DNS();
/** This method will start the reverse lookup of an ip given in dotted decimal
* format, e.g. 1.2.3.4, and returns true if the lookup was successfully
* initiated.
*/
bool ReverseLookup(const std::string &ip, bool ins);
/** This method will start the forward lookup of a hostname, e.g. www.inspircd.org,
* and returns true if the lookup was successfully initiated.
*/
bool ForwardLookup(const std::string &host, bool ins);
/** Used by modules to perform a dns lookup but have the socket engine poll a module, instead of the dns object directly.
*/
bool ForwardLookupWithFD(const std::string &host, int &fd);
/** This method will return true when the lookup is completed. It uses poll internally
* to determine the status of the socket.
*/
bool HasResult();
/** This method will return true if the lookup's fd matches the one provided
*/
bool HasResult(int fd);
/** This method returns the result of your query as a string, depending upon wether you
* called DNS::ReverseLookup() or DNS::ForwardLookup.
*/
std::string GetResult();
std::string GetResultIP();
/** This method returns the file handle used by the dns query socket or zero if the
* query is invalid for some reason, e.g. the dns server not responding.
*/
int GetFD();
void SetNS(const std::string &dnsserver);
};
/**
* The Resolver class is a high-level abstraction for resolving DNS entries.
* It can do forward and reverse IPv4 lookups, and when IPv6 is supported, will
* also be able to do those, transparent of protocols. Module developers must
* extend this class via inheritence, and then insert a pointer to their derived
* class into the core using Server::AddResolver(). Once you have done this,
* the class will be able to receive callbacks. There are two callbacks which
* can occur by calling virtual methods, one is a success situation, and the other
* an error situation.
*/
class Resolver : public Extensible
{
private:
/**
* The lowlevel DNS object used by Resolver
*/
DNS Query;
/**
* The input data, either a host or an IP address
*/
std::string input;
/**
* True if a forward lookup is being performed, false if otherwise
*/
bool fwd;
/**
* The DNS erver being used for lookups. If this is an empty string,
* the value of ServerConfig::DNSServer is used instead.
*/
std::string server;
/**
* The file descriptor used for the DNS lookup
*/
int fd;
/**
* The output data, e.g. a hostname or an IP.
*/
std::string result;
public:
/**
* Initiate DNS lookup. Your class should not attempt to delete or free these
* objects, as the core will do this for you. They must always be created upon
* the heap using new, as you cannot be sure at what time they will be deleted.
* Allocating them on the stack or attempting to delete them yourself could cause
* the object to go 'out of scope' and cause a segfault in the core if the result
* arrives at a later time.
* @param source The IP or hostname to resolve
* @param forward Set to true to perform a forward lookup (hostname to ip) or false
* to perform a reverse lookup (ip to hostname). Lookups on A records and PTR
* records are supported. CNAME and MX are not supported by this resolver.
* @param dnsserver This optional parameter specifies an alterate nameserver to use.
* If it is not specified, or is an empty string, the value of ServerConfig::DNSServer
* is used instead.
* @throw ModuleException This class may throw an instance of ModuleException, in the
* event there are no more file descriptors, or a similar hard error occurs such as
* the network being down.
*/
Resolver(const std::string &source, bool forward, const std::string &dnsserver);
/**
* The default destructor does nothing.
*/
virtual ~Resolver();
/**
* When your lookup completes, this method will be called.
* @param result The resulting DNS lookup, either an IP address or a hostname.
*/
virtual void OnLookupComplete(const std::string &result);
/**
* If an error occurs (such as NXDOMAIN, no domain name found) then this method
* will be called.
* @param e A ResolverError enum containing the error type which has occured.
*/
virtual void OnError(ResolverError e);
/**
* This method is called by the core when the object's file descriptor is ready
* for reading, and will then dispatch a call to either OnLookupComplete or
* OnError. You should never call this method yourself.
*/
bool ProcessResult();
/**
* Returns the file descriptor of this class. This is primarily used by the core
* to determine where in various tables to place a pointer to your class, but it
* is safe to call and use this method.
*/
int GetFd();
};
/**
* Clear the pointer table used for Resolver classes
*/
void init_dns();
/**
* Deal with a Resolver class which has become writeable
*/
void dns_deal_with_classes(int fd);
/**
* Add a resolver class to our active table
*/
bool dns_add_class(Resolver* r);
#ifdef THREADED_DNS
/** This is the handler function for multi-threaded DNS.
* It cannot be a class member as pthread will not let us
* create a thread whos handler function is a member of
* a class (ugh).
*/
void* dns_task(void* arg);
#endif
#endif
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