Network Address Resolution

Data Structures
struct	pj_hostent
struct	pj_addrinfo

Macros
#define	h_addr   h_addr_list[0]

Functions
pj_status_t	pj_gethostbyname (const pj_str_t *name, pj_hostent *he)
pj_status_t	pj_gethostip (int af, pj_sockaddr *addr)
pj_status_t	pj_getipinterface (int af, const pj_str_t *dst, pj_sockaddr *itf_addr, pj_bool_t allow_resolve, pj_sockaddr *p_dst_addr)
pj_status_t	pj_getdefaultipinterface (int af, pj_sockaddr *addr)
pj_status_t	pj_getaddrinfo (int af, const pj_str_t *name, unsigned *count, pj_addrinfo ai[])

Detailed Description

This module provides function to resolve Internet address of the specified host name. To resolve a particular host name, application can just call pj_gethostbyname().

Example:

  ...
  pj_hostent he;
  pj_status_t rc;
  pj_str_t host = pj_str("host.example.com");

  rc = pj_gethostbyname( &host, &he);
  if (rc != PJ_SUCCESS) {
     char errbuf[80];
     pj_strerror( rc, errbuf, sizeof(errbuf));
     PJ_LOG(2,("sample", "Unable to resolve host, error=%s", errbuf));
     return rc;
  }

  // process address...
  addr.sin_addr.s_addr = *(pj_uint32_t*)he.h_addr;
  ...

It's pretty simple really...

Macro Definition Documentation

h_addr

#define h_addr   h_addr_list[0]

Shortcut to h_addr_list[0]

Function Documentation

pj_getaddrinfo()

pj_status_t pj_getaddrinfo	(	int	af,
		const pj_str_t *	name,
		unsigned *	count,
		pj_addrinfo	ai[]
	)

This function translates the name of a service location (for example, a host name) and returns a set of addresses and associated information to be used in creating a socket with which to address the specified service.

Parameters

af	The desired address family to query. Valid values are pj_AF_INET(), pj_AF_INET6(), or pj_AF_UNSPEC().
name	Descriptive name or an address string, such as host name.
count	On input, it specifies the number of elements in ai array. On output, this will be set with the number of address informations found for the specified name.
ai	Array of address info to be filled with the information about the host.

Returns

PJ_SUCCESS on success, or the appropriate error code.

pj_getdefaultipinterface()

pj_status_t pj_getdefaultipinterface	(	int	af,
		pj_sockaddr *	addr
	)

Get the IP address of the default interface. Default interface is the interface of the default route.

Parameters

af	The desired address family to query. Valid values are pj_AF_INET() or pj_AF_INET6().
addr	On successful resolution, the address family and address part of this socket address will be filled up with the host IP address, in network byte order. Other parts of the socket address are untouched.

Returns

PJ_SUCCESS on success, or the appropriate error code.

pj_gethostbyname()

pj_status_t pj_gethostbyname	(	const pj_str_t *	name,
		pj_hostent *	he
	)

This function fills the structure of type pj_hostent for a given host name. For host resolution function that also works with IPv6, please see pj_getaddrinfo().

Parameters

name	Host name to resolve. Specifying IPv4 address here may fail on some platforms (e.g. Windows)
he	The pj_hostent structure to be filled. Note that the pointers in this structure points to temporary variables which value will be reset upon subsequent invocation.

Returns

PJ_SUCCESS, or the appropriate error codes.

pj_gethostip()

pj_status_t pj_gethostip	(	int	af,
		pj_sockaddr *	addr
	)

Resolve the primary IP address of local host.

Parameters

af	The desired address family to query. Valid values are pj_AF_INET() or pj_AF_INET6().
addr	On successful resolution, the address family and address part of this socket address will be filled up with the host IP address, in network byte order. Other parts of the socket address are untouched.

Returns

PJ_SUCCESS on success, or the appropriate error code.

pj_getipinterface()

pj_status_t pj_getipinterface	(	int	af,
		const pj_str_t *	dst,
		pj_sockaddr *	itf_addr,
		pj_bool_t	allow_resolve,
		pj_sockaddr *	p_dst_addr
	)

Get the interface IP address to send data to the specified destination.

Parameters

af	The desired address family to query. Valid values are pj_AF_INET() or pj_AF_INET6().
dst	The destination host.
itf_addr	On successful resolution, the address family and address part of this socket address will be filled up with the host IP address, in network byte order. Other parts of the socket address should be ignored.
allow_resolve	If dst may contain hostname (instead of IP address), specify whether hostname resolution should be performed. If not, default interface address will be returned.
p_dst_addr	If not NULL, it will be filled with the IP address of the destination host.

Returns

PJ_SUCCESS on success, or the appropriate error code.