Xgetifaddrs.c File Reference

Xgetifaddrs(), Xfreeifaddrs() - get interface addresses. More...

#include "Xsocket.h"

Functions
int	Xgetifaddrs (struct ifaddrs **ifap)
	get a list of XIA network interfaces More...
void	Xfreeifaddrs (struct ifaddrs *ifa)
	free memory allocated by Xgetifaddrs More...

Function Documentation

void Xfreeifaddrs

(

struct ifaddrs *

ifa

)

Free's the memory allocated by XgetifAddrs().

Parameters

ifa	pointer to ifaddr structure to be freed.

Returns

void

int Xgetifaddrs

(

struct ifaddrs **

ifap

)

The Xgetifaddrs() function creates a linked list of structures describing XIA enabled network interfaces of the local system, and stores the address of the first item of the list in *ifap. The list consists of ifaddrs structures, defined as follows:

 struct ifaddrs {
        struct ifaddrs  *ifa_next;    // Next item in list
        char            *ifa_name;    // Name of interface
        unsigned int     ifa_flags;   // Flags from SIOCGIFFLAGS
        struct sockaddr *ifa_addr;    // Address of interface
        struct sockaddr *ifa_netmask; // Netmask of interface
        union {
            struct sockaddr *ifu_broadaddr;
            // Broadcast address of interface
            struct sockaddr *ifu_dstaddr;
            // Point-to-point destination address
        } ifa_ifu;
        #define          ifa_broadaddr ifa_ifu.ifu_broadaddr
        #define          ifa_dstaddr   ifa_ifu.ifu_dstaddr
        void            *ifa_data;    // Address-specific data
    };

The ifa_next field contains a pointer to the next structure on the list, or NULL if this is the last item of the list.

The ifa_name points to the null-terminated interface name.

The ifa_flags field contains the interface flags, as returned by the SIOCGIFFLAGS ioctl(2) operation (see netdevice(7) for a list of these flags).

The ifa_addr field points to a structure containing the interface address. Under XIA, these will all be of type sockaddr_x. This field may contain a null pointer.

The ifa_netmask field points will always be NULL under XIA.

Currently the ifa_ifu union will never contain a broadcast address.

The ifa_data pointer will always be NULL

The data returned by Xgetifaddrs() is dynamically allocated and should be freed using Xfreeifaddrs() when no longer needed.

Parameters

ifap	pointer to a pointer to accept the returned ifaddrs structure

Returns

0 on success

-1 on error with errno set appropriately.