-static void ipv4_build_icmp(struct sk_buff *skb, struct sk_buff *nskb,
- unsigned int mtu, unsigned int payload_length)
-{
- struct iphdr *iph, *old_iph = ip_hdr(skb);
- struct icmphdr *icmph;
- u8 *payload;
-
- iph = (struct iphdr *)skb_put(nskb, sizeof(struct iphdr));
- icmph = (struct icmphdr *)skb_put(nskb, sizeof(struct icmphdr));
- payload = skb_put(nskb, payload_length);
-
- /* IP */
- iph->version = 4;
- iph->ihl = sizeof(struct iphdr) >> 2;
- iph->tos = (old_iph->tos & IPTOS_TOS_MASK) |
- IPTOS_PREC_INTERNETCONTROL;
- iph->tot_len = htons(sizeof(struct iphdr)
- + sizeof(struct icmphdr)
- + payload_length);
- get_random_bytes(&iph->id, sizeof(iph->id));
- iph->frag_off = 0;
- iph->ttl = IPDEFTTL;
- iph->protocol = IPPROTO_ICMP;
- iph->daddr = old_iph->saddr;
- iph->saddr = old_iph->daddr;
-
- ip_send_check(iph);
-
- /* ICMP */
- icmph->type = ICMP_DEST_UNREACH;
- icmph->code = ICMP_FRAG_NEEDED;
- icmph->un.gateway = htonl(mtu);
- icmph->checksum = 0;
-
- nskb->csum = csum_partial((u8 *)icmph, sizeof(struct icmphdr), 0);
- nskb->csum = skb_copy_and_csum_bits(skb, (u8 *)old_iph - skb->data,
- payload, payload_length,
- nskb->csum);
- icmph->checksum = csum_fold(nskb->csum);
-}
-
-#if defined(CONFIG_IPV6) || defined(CONFIG_IPV6_MODULE)
-static bool ipv6_should_icmp(struct sk_buff *skb)
-{
- struct ipv6hdr *old_ipv6h = ipv6_hdr(skb);
- int addr_type;
- int payload_off = (u8 *)(old_ipv6h + 1) - skb->data;
- u8 nexthdr = ipv6_hdr(skb)->nexthdr;
-
- /* Check source address is valid. */
- addr_type = ipv6_addr_type(&old_ipv6h->saddr);
- if (addr_type & IPV6_ADDR_MULTICAST || addr_type == IPV6_ADDR_ANY)
- return false;
-
- /* Don't reply to unspecified addresses. */
- if (ipv6_addr_type(&old_ipv6h->daddr) == IPV6_ADDR_ANY)
- return false;
-
- /* Don't respond to ICMP error messages. */
- payload_off = ipv6_skip_exthdr(skb, payload_off, &nexthdr);
- if (payload_off < 0)
- return false;
-
- if (nexthdr == NEXTHDR_ICMP) {
- u8 icmp_type, *icmp_typep;
-
- icmp_typep = skb_header_pointer(skb, payload_off +
- offsetof(struct icmp6hdr,
- icmp6_type),
- sizeof(icmp_type), &icmp_type);
-
- if (!icmp_typep || !(*icmp_typep & ICMPV6_INFOMSG_MASK))
- return false;
- }
-
- return true;
-}
-
-static void ipv6_build_icmp(struct sk_buff *skb, struct sk_buff *nskb,
- unsigned int mtu, unsigned int payload_length)
-{
- struct ipv6hdr *ipv6h, *old_ipv6h = ipv6_hdr(skb);
- struct icmp6hdr *icmp6h;
- u8 *payload;
-
- ipv6h = (struct ipv6hdr *)skb_put(nskb, sizeof(struct ipv6hdr));
- icmp6h = (struct icmp6hdr *)skb_put(nskb, sizeof(struct icmp6hdr));
- payload = skb_put(nskb, payload_length);
-
- /* IPv6 */
- ipv6h->version = 6;
- ipv6h->priority = 0;
- memset(&ipv6h->flow_lbl, 0, sizeof(ipv6h->flow_lbl));
- ipv6h->payload_len = htons(sizeof(struct icmp6hdr)
- + payload_length);
- ipv6h->nexthdr = NEXTHDR_ICMP;
- ipv6h->hop_limit = IPV6_DEFAULT_HOPLIMIT;
- ipv6_addr_copy(&ipv6h->daddr, &old_ipv6h->saddr);
- ipv6_addr_copy(&ipv6h->saddr, &old_ipv6h->daddr);
-
- /* ICMPv6 */
- icmp6h->icmp6_type = ICMPV6_PKT_TOOBIG;
- icmp6h->icmp6_code = 0;
- icmp6h->icmp6_cksum = 0;
- icmp6h->icmp6_mtu = htonl(mtu);
-
- nskb->csum = csum_partial((u8 *)icmp6h, sizeof(struct icmp6hdr), 0);
- nskb->csum = skb_copy_and_csum_bits(skb, (u8 *)old_ipv6h - skb->data,
- payload, payload_length,
- nskb->csum);
- icmp6h->icmp6_cksum = csum_ipv6_magic(&ipv6h->saddr, &ipv6h->daddr,
- sizeof(struct icmp6hdr)
- + payload_length,
- ipv6h->nexthdr, nskb->csum);