if_nameindex.c

unix网络编程第一卷socket编程书上的全部源代码

/* include if_nameindex */
#include	"unpifi.h"
#include	"unproute.h"

struct if_nameindex *
if_nameindex(void)
{
	char				*buf, *next, *lim;
	size_t				len;
	struct if_msghdr	*ifm;
	struct sockaddr		*sa, *rti_info[RTAX_MAX];
	struct sockaddr_dl	*sdl;
	struct if_nameindex	*result, *ifptr;
	char				*namptr;

	if ( (buf = net_rt_iflist(0, 0, &len)) == NULL)
		return(NULL);

	if ( (result = malloc(len)) == NULL)	/* overestimate */
		return(NULL);
	ifptr = result;
	namptr = (char *) result + len;	/* names start at end of buffer */

	lim = buf + len;
	for (next = buf; next < lim; next += ifm->ifm_msglen) {
		ifm = (struct if_msghdr *) next;
		if (ifm->ifm_type == RTM_IFINFO) {
			sa = (struct sockaddr *) (ifm + 1);
			get_rtaddrs(ifm->ifm_addrs, sa, rti_info);
			if ( (sa = rti_info[RTAX_IFP]) != NULL) {
				if (sa->sa_family == AF_LINK) {
					sdl = (struct sockaddr_dl *) sa;
					namptr -= sdl->sdl_nlen + 1;
					strncpy(namptr, &sdl->sdl_data[0], sdl->sdl_nlen);
					namptr[sdl->sdl_nlen] = 0;	/* null terminate */
					ifptr->if_name = namptr;
					ifptr->if_index = sdl->sdl_index;
					ifptr++;
				}
			}

		}
	}
	ifptr->if_name = NULL;	/* mark end of array of structs */
	ifptr->if_index = 0;
	free(buf);
	return(result);			/* caller must free() this when done */
}
/* end if_nameindex */

/* include if_freenameindex */
void
if_freenameindex(struct if_nameindex *ptr)
{
	free(ptr);
}
/* end if_freenameindex */

struct if_nameindex *
If_nameindex(void)
{
	struct if_nameindex	*ifptr;

	if ( (ifptr = if_nameindex()) == NULL)
		err_quit("if_nameindex error");
	return(ifptr);
}