curl/lib/hostip.h

#ifndef __HOSTIP_H
#define __HOSTIP_H
/***************************************************************************
 *                                  _   _ ____  _     
 *  Project                     ___| | | |  _ \| |    
 *                             / __| | | | |_) | |    
 *                            | (__| |_| |  _ <| |___ 
 *                             \___|\___/|_| \_\_____|
 *
 * Copyright (C) 1998 - 2004, Daniel Stenberg, <daniel@haxx.se>, et al.
 *
 * This software is licensed as described in the file COPYING, which
 * you should have received as part of this distribution. The terms
 * are also available at http://curl.haxx.se/docs/copyright.html.
 * 
 * You may opt to use, copy, modify, merge, publish, distribute and/or sell
 * copies of the Software, and permit persons to whom the Software is
 * furnished to do so, under the terms of the COPYING file.
 *
 * This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
 * KIND, either express or implied.
 *
 * $Id$
 ***************************************************************************/

#include "setup.h"
#include "hash.h"

struct addrinfo;
struct hostent;
struct SessionHandle;
struct connectdata;

void Curl_global_host_cache_init(void);
void Curl_global_host_cache_dtor(void);
curl_hash *Curl_global_host_cache_get(void);

#define Curl_global_host_cache_use(__p) ((__p)->set.global_dns_cache)

struct Curl_dns_entry {
  Curl_addrinfo *addr;
  time_t timestamp;
  long inuse;      /* use-counter, make very sure you decrease this
                      when you're done using the address you received */
};

/*
 * Curl_resolv() returns an entry with the info for the specified host
 * and port.
 *
 * The returned data *MUST* be "unlocked" with Curl_resolv_unlock() after
 * use, or we'll leak memory!
 */
int Curl_resolv(struct connectdata *conn,
                char *hostname,
                int port,
                struct Curl_dns_entry **dnsentry);

/*
 * Curl_ipvalid() checks what CURL_IPRESOLVE_* requirements that might've
 * been set and returns TRUE if they are OK.
 */
bool Curl_ipvalid(struct SessionHandle *data);

/*
 * Curl_getaddrinfo() is the generic low-level name resolve API within this
 * source file. There are several versions of this function - for different
 * name resolve layers (selected at build-time). They all take this same set
 * of arguments
 */
Curl_addrinfo *Curl_getaddrinfo(struct connectdata *conn,
                                char *hostname,
                                int port,
                                int *waitp);

CURLcode Curl_is_resolved(struct connectdata *conn,
                          struct Curl_dns_entry **dns);
CURLcode Curl_wait_for_resolv(struct connectdata *conn,
                              struct Curl_dns_entry **dnsentry);

/* Curl_fdset() is a generic function that exists in multiple versions
   depending on what name resolve technology we've built to use. The function
   is called from the curl_multi_fdset() function */
CURLcode Curl_fdset(struct connectdata *conn,
                    fd_set *read_fd_set,
                    fd_set *write_fd_set,
                    int *max_fdp);
/* unlock a previously resolved dns entry */
void Curl_resolv_unlock(struct SessionHandle *data, struct Curl_dns_entry *dns);

/* for debugging purposes only: */
void Curl_scan_cache_used(void *user, void *ptr);

/* free name info */
void Curl_freeaddrinfo(Curl_addrinfo *freeaddr);

/* make a new dns cache and return the handle */
curl_hash *Curl_mk_dnscache(void);

/* prune old entries from the DNS cache */
void Curl_hostcache_prune(struct SessionHandle *data);

#ifdef CURLDEBUG
void curl_dofreeaddrinfo(struct addrinfo *freethis,
                         int line, const char *source);
int curl_dogetaddrinfo(char *hostname, char *service,
                       struct addrinfo *hints,
                       struct addrinfo **result,
                       int line, const char *source);
int curl_dogetnameinfo(const struct sockaddr *sa, socklen_t salen,
                       char *host, size_t hostlen,
                       char *serv, size_t servlen, int flags,
                       int line, const char *source);
#endif

/* This is the callback function that is used when we build with asynch
   resolve */
void Curl_addrinfo_callback(void *arg,
                            int status,
                            Curl_addrinfo *hostent);

/* This is a utility-function for ipv4-builds to create a hostent struct
   from a numerical-only IP address */
Curl_addrinfo *Curl_ip2addr(unsigned long num, char *hostname);

/* relocate a hostent struct */
void Curl_hostent_relocate(struct hostent *h, long offset);

/* copy a Curl_addrinfo struct, currently this only supports copying
   a hostent (ipv4-style) struct */
Curl_addrinfo *Curl_addrinfo_copy(Curl_addrinfo *orig);

/*
 * (IPv6) Curl_printable_address() returns a printable version of the
 * ai->ai_addr address given in the 2nd argument. The first should be the
 * ai->ai_family and the result will be stored in the buf that is bufsize
 * bytes big.
 */
const char *Curl_printable_address(int af, void *addr,
                                   char *buf, size_t bufsize);

/*
 * Curl_cache_addr() stores a 'Curl_addrinfo' struct in the DNS cache.
 *
 * Returns the Curl_dns_entry entry pointer or NULL if the storage failed.
 */
struct Curl_dns_entry *
Curl_cache_addr(struct SessionHandle *data, Curl_addrinfo *addr,
                char *hostname, int port);

#ifndef INADDR_NONE
#define CURL_INADDR_NONE (in_addr_t) ~0
#else
#define CURL_INADDR_NONE INADDR_NONE
#endif

/*
 * Setup comfortable CURLRES_* defines to use in the host*.c sources.
 */

#ifdef USE_ARES
#define CURLRES_ASYNCH
#define CURLRES_ARES
#endif

#ifdef USE_THREADING_GETHOSTBYNAME
#define CURLRES_ASYNCH
#define CURLRES_THREADED
#endif

#ifdef USE_THREADING_GETADDRINFO
#define CURLRES_ASYNCH
#define CURLRES_THREADED
#endif

#ifdef ENABLE_IPV6
#define CURLRES_IPV6
#else
#define CURLRES_IPV4
#endif

#ifdef CURLRES_IPV4
#if !defined(HAVE_GETHOSTBYNAME_R) || defined(CURLRES_ASYNCH)
/* If built for ipv4 and missing gethostbyname_r(), or if using async name
   resolve, we need the Curl_addrinfo_copy() function (which itself needs the
   Curl_hostent_relocate() function)) */
#define CURLRES_ADDRINFO_COPY
#define CURLRES_HOSTENT_RELOCATE
#endif
#endif /* IPv4-only */

#ifdef HAVE_GETHOSTBYNAME_R_6
#define CURLRES_HOSTENT_RELOCATE
#endif

#ifdef HAVE_GETHOSTBYNAME_R_5
#define CURLRES_HOSTENT_RELOCATE
#endif

#ifndef CURLRES_ASYNCH
#define CURLRES_SYNCH
#endif

/* Allocate enough memory to hold the full name information structs and
 * everything. OSF1 is known to require at least 8872 bytes. The buffer
 * required for storing all possible aliases and IP numbers is according to
 * Stevens' Unix Network Programming 2nd edition, p. 304: 8192 bytes!
 */
#define CURL_HOSTENT_SIZE 9000

#define CURL_TIMEOUT_RESOLVE 300 /* when using asynch methods, we allow this
                                    many seconds for a name resolve */

#ifdef CURLRES_ARES
#define CURL_ASYNC_SUCCESS ARES_SUCCESS
#else
#define CURL_ASYNC_SUCCESS CURLE_OK
#endif

#endif