NAME

if_util — system networking interface utility routines

LIBRARY

PDEL Library (libpdel, -lpdel)

SYNOPSIS

#include <sys/types.h>
#include <netinet/in.h>
#include <pdel/net/if_util.h>

int
if_get_list(char ***listp, const char *mtype);

int
if_get_type(const char *ifname);

int
if_get_flags(const char *ifname);

int
if_set_flags(const char *ifname, int flags);

int
if_get_mtu(const char *ifname);

int
if_set_mtu(const char *ifname, u_int mtu);

int
if_get_link_addr(const char *ifname, struct sockaddr_dl **sdlp, const char *mtype);

int
if_get_ip_addrs(const char *ifname, struct in_addr **iplistp, struct in_addr **nmlistp, const char *mtype);

int
if_get_ip_addr(const char *ifname, struct in_addr *ipp, struct in_addr *nmp);

int
if_add_ip_addr(const char *iface, struct in_addr ip, struct in_addr mask, struct in_addr dest);

int
if_del_ip_addr(const char *iface, struct in_addr ip, struct in_addr mask, struct in_addr dest);

int
if_get_arp(struct in_addr ip, u_char *ether);

int
if_set_arp(struct in_addr ip, const u_char *ether, int temp, int publish);

int
if_flush_arp(void);

DESCRIPTION

These functions are useful for accessing and configuring system networking interfaces, especially for IP networking.

if_get_list() constructs a list of the names of all interfaces present in the system. Zero or more strings are allocated and pointed to by the elements of a newly allocated array of pointers. The length of the array is returned by if_get_list() and a pointer to the array is stored in *listp. Each string, as well as the array itself, is allocated with typed_mem(3) type mtype. The caller is responsible for eventually freeing the individual strings as well as the array itself.

if_get_type() returns the type of the interface named ifname. The interface types are defined in the include file <net/if_types.h>.

if_get_flags() gets the flags associated with the interface named ifname. The interface flags are defined in the include file <net/if.h>.

if_set_flags() attempts to set the flags associated with the interface named ifname.

if_get_mtu() returns the current MTU associated with the interface named ifname.

if_set_mtu() attempts to set the MTU associated with the interface named ifname.

if_get_link_addr() retrieves the link layer address associated with the interface named ifname, allocates a buffer with typed_mem(3) type mtype to hold it, and stores a pointer to the buffer in *sdlp. The caller is responsible for eventually freeing the buffer. The struct sockaddr_dl type is defined in the include file <net/if_dl.h>.

if_get_ip_addrs() retrieves the list of all IP addresses (with netmasks) configured on the interface named ifname. The IP addresses and netmasks are stored in two arrays allocated with typed_mem(3) type mtype, and pointers to these arrays are stored in *iplistp and *nmlistp, respectively. The caller is responsible for eventually freeing the arrays. The length of the arrays is returned.

if_get_ip_addr() retrieves the first IP address and netmask configured on the interface named ifname and stores them in *ipp and *nmp, respectively.

if_add_ip_addr() configures a new IP address on the interface named ifname, using the netmask mask and destination dest. Existing IP addresses configured on the interface are not removed. dest should be 0.0.0.0 for non-point-to-point interfaces.

if_del_ip_addr() removes a configured IP address, netmask, and destination from the interface named ifname. dest should be 0.0.0.0 for non-point-to-point interfaces.

if_get_arp() retrieves the ARP table entry associated with the IP address ip and stores it in the buffer pointed to by ether, which must be at least six bytes long.

if_set_arp() sets an ARP table entry for the IP address ip to resolve to the Ethernet address pointed to by ether. The temp flag indicates a temporary entry. The publish flag indicates that the local machine should proxy-ARP for this IP address. If ether is NULL, any matching ARP table entry is cleared. The

if_flush_arp() clears the ARP table.

RETURN VALUES

All of the above functions return -1 to indicate an error, with errno set appropriately.

HISTORY

The PDEL library was developed at Packet Design, LLC. http://www.packetdesign.com/

AUTHORS

Archie Cobbs ⟨archie@freebsd.org⟩

BUGS

There is no way to retrieve destination addresses configured on a point-to-point interface.

These routines should be less IPv4-centric.