-/* return:
- * 1 if the UDP system should process it
- * 0 if we should drop this packet
- * -1 if it should get processed by xfrm4_rcv_encap
- */
-static int udp_encap_rcv(struct sock * sk, struct sk_buff *skb)
-{
-#ifndef CONFIG_XFRM
- return 1;
-#else
- struct udp_sock *up = udp_sk(sk);
- struct udphdr *uh;
- struct iphdr *iph;
- int iphlen, len;
-
- __u8 *udpdata;
- __be32 *udpdata32;
- __u16 encap_type = up->encap_type;
-
- /* if we're overly short, let UDP handle it */
- len = skb->len - sizeof(struct udphdr);
- if (len <= 0)
- return 1;
-
- /* if this is not encapsulated socket, then just return now */
- if (!encap_type)
- return 1;
-
- /* If this is a paged skb, make sure we pull up
- * whatever data we need to look at. */
- if (!pskb_may_pull(skb, sizeof(struct udphdr) + min(len, 8)))
- return 1;
-
- /* Now we can get the pointers */
- uh = udp_hdr(skb);
- udpdata = (__u8 *)uh + sizeof(struct udphdr);
- udpdata32 = (__be32 *)udpdata;
-
- switch (encap_type) {
- default:
- case UDP_ENCAP_ESPINUDP:
- /* Check if this is a keepalive packet. If so, eat it. */
- if (len == 1 && udpdata[0] == 0xff) {
- return 0;
- } else if (len > sizeof(struct ip_esp_hdr) && udpdata32[0] != 0) {
- /* ESP Packet without Non-ESP header */
- len = sizeof(struct udphdr);
- } else
- /* Must be an IKE packet.. pass it through */
- return 1;
- break;
- case UDP_ENCAP_ESPINUDP_NON_IKE:
- /* Check if this is a keepalive packet. If so, eat it. */
- if (len == 1 && udpdata[0] == 0xff) {
- return 0;
- } else if (len > 2 * sizeof(u32) + sizeof(struct ip_esp_hdr) &&
- udpdata32[0] == 0 && udpdata32[1] == 0) {
-
- /* ESP Packet with Non-IKE marker */
- len = sizeof(struct udphdr) + 2 * sizeof(u32);
- } else
- /* Must be an IKE packet.. pass it through */
- return 1;
- break;
- }
-
- /* At this point we are sure that this is an ESPinUDP packet,
- * so we need to remove 'len' bytes from the packet (the UDP
- * header and optional ESP marker bytes) and then modify the
- * protocol to ESP, and then call into the transform receiver.
- */
- if (skb_cloned(skb) && pskb_expand_head(skb, 0, 0, GFP_ATOMIC))
- return 0;
-
- /* Now we can update and verify the packet length... */
- iph = ip_hdr(skb);
- iphlen = iph->ihl << 2;
- iph->tot_len = htons(ntohs(iph->tot_len) - len);
- if (skb->len < iphlen + len) {
- /* packet is too small!?! */
- return 0;
- }
-
- /* pull the data buffer up to the ESP header and set the
- * transport header to point to ESP. Keep UDP on the stack
- * for later.
- */
- __skb_pull(skb, len);
- skb_reset_transport_header(skb);
-
- /* modify the protocol (it's ESP!) */
- iph->protocol = IPPROTO_ESP;
-
- /* and let the caller know to send this into the ESP processor... */
- return -1;
-#endif
-}
-