Hi,
On Thu, Jan 15, 2009 at 12:27:14PM +1300, Michael Kerrisk wrote:
> On Tue, Dec 9, 2008 at 3:56 PM, Petr Baudis <pasky@xxxxxxx> wrote:
> > I'm open to relicensing to any of the standard licences, this one
> > should be compatible even with the classic BSD licence.
>
> By now, I think little, if any, of the BSD page remains. I'd be
> inclined to switch to the verbatim license? Okay with you?
sure.
> .SH ERRORS
> .BR getifaddrs ()
> may fail and set
> .I errno
> for any of the errors specified for
> .BR socket (2),
> .BR bind (2),
> .\" FIXME Petr, I added getsockname() and recvmsg(); do you agree?
Makes sense.
> .BR getsockname (2),
> .BR recvmsg (2),
> .BR sendto (2),
> .BR malloc (3),
> or
> .BR realloc (3).
> .SH VERSIONS
> The
> .BR getifaddrs ()
> function first appeared in glibc 2.3, but before glibc 2.3.3,
> the implementation only supported IPv4 addresses;
> IPv6 support was added in glibc 2.3.3.
We might add that support for getting addresses other than IPv4 is
available only if the kernel supports netlink.
> .SH EXAMPLE
> The program below demonstrates the use of
> .BR getifaddrs (),
> .BR freeifaddrs (),
> and
> .BR inet_ntop (3).
getnameinfo() now.
> Here is what we see when running this program on one system:
> .in +4n
> .nf
>
> $ \fB./a.out\fP
> lo address family: 17 (AF_PACKET)
> eth0 address family: 17 (AF_PACKET)
> lo address family: 2 (AF_INET)
> address: <127.0.0.1>
> eth0 address family: 2 (AF_INET)
> address: <10.1.1.4>
> lo address family: 10 (AF_INET6)
> address: <::1>
> eth0 address family: 10 (AF_INET6)
> address: <fe80::2d0:59ff:feda:eb51%eth0>
> .fi
> .in
> .SS Program source
> \&
> .nf
> #include <arpa/inet.h>
> #include <sys/socket.h>
> #include <netdb.h>
> #include <ifaddrs.h>
> #include <stdio.h>
> #include <stdlib.h>
> #include <unistd.h>
>
> int
> main(int argc, char *argv[])
> {
> struct ifaddrs *ifaddr;
> struct net_device_stats *ndsp;
Unused.
> int family, s;
> char host[NI_MAXHOST];
>
> if (getifaddrs(&ifaddr) == \-1) {
> perror("getifaddrs");
> exit(EXIT_FAILURE);
> }
>
> while (ifaddr != NULL) { /* Walk through linked list */
> family = ifaddr\->ifa_addr\->sa_family;
>
> /* Display interface name and family (including symbolic
> form of the latter for the common families) */
>
> printf("%\-6s address family: %d%s\\n",
I'd %s\t here instead, personally.
> ifaddr\->ifa_name, family,
> (family == AF_PACKET) ? " (AF_PACKET)" :
> (family == AF_INET) ? " (AF_INET)" :
> (family == AF_INET6) ? " (AF_INET6)" : "");
>
> /* For an AF_INET* interface address, display the address */
>
> if (family == AF_INET || family == AF_INET6) {
> s = getnameinfo(ifaddr\->ifa_addr,
> (family == AF_INET) ? sizeof(struct sockaddr_in) :
> sizeof(struct sockaddr_in6),
> host, NI_MAXHOST, NULL, 0, NI_NUMERICHOST);
> if (s != 0) {
> printf("getnameinfo() failed: %s\\n", gai_strerror(s));
> exit(EXIT_FAILURE);
> }
I have mixed feelings about this test, since superfluous tests IMHO
obscure the example. Not sure if it can actually ever fail...
> printf("\\taddress: <%s>\\n", host);
> }
>
> ifaddr = ifaddr\->ifa_next;
> }
>
> freeifaddrs(ifaddr);
> exit(EXIT_SUCCESS);
> }
--
Petr "Pasky" Baudis
The average, healthy, well-adjusted adult gets up at seven-thirty
in the morning feeling just terrible. -- Jean Kerr
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