Function rtsock_msg_buffer

freebsd/net/rtsock.c:1639–1763

* Writes information related to @rtinfo object to preallocated buffer. * Stores needed size in @plen. If @w is NULL, calculates size without * writing. * Used for sysctl dumps and rtsock answers (RTM_DEL/RTM_GET) generation. * * Returns 0 on success. * */

 *
 */
static int
rtsock_msg_buffer(int type, struct rt_addrinfo *rtinfo, struct walkarg *w, int *plen)
{
	struct sockaddr_storage ss;
	int len, buflen = 0, dlen, i;
	caddr_t cp = NULL;
	struct rt_msghdr *rtm = NULL;
#ifdef INET6
	struct sockaddr_in6 *sin6;
#endif
#ifdef COMPAT_FREEBSD32
	bool compat32 = false;
#endif

	switch (type) {
	case RTM_DELADDR:
	case RTM_NEWADDR:
		if (w != NULL && w->w_op == NET_RT_IFLISTL) {
#ifdef COMPAT_FREEBSD32
			if (w->w_req->flags & SCTL_MASK32) {
				len = sizeof(struct ifa_msghdrl32);
				compat32 = true;
			} else
#endif
				len = sizeof(struct ifa_msghdrl);
		} else
			len = sizeof(struct ifa_msghdr);
		break;

	case RTM_IFINFO:
#ifdef COMPAT_FREEBSD32
		if (w != NULL && w->w_req->flags & SCTL_MASK32) {
			if (w->w_op == NET_RT_IFLISTL)
				len = sizeof(struct if_msghdrl32);
			else
				len = sizeof(struct if_msghdr32);
			compat32 = true;
			break;
		}
#endif
		if (w != NULL && w->w_op == NET_RT_IFLISTL)
			len = sizeof(struct if_msghdrl);
		else
			len = sizeof(struct if_msghdr);
		break;

	case RTM_NEWMADDR:
		len = sizeof(struct ifma_msghdr);
		break;

	default:
		len = sizeof(struct rt_msghdr);
	}

	if (w != NULL) {
		rtm = (struct rt_msghdr *)w->w_tmem;
		buflen = w->w_tmemsize - len;
		cp = (caddr_t)w->w_tmem + len;