-static bool
-ipv4_should_icmp(struct sk_buff *skb)
-{
- struct iphdr *old_iph = ip_hdr(skb);
-
- /* Don't respond to L2 broadcast. */
- if (is_multicast_ether_addr(eth_hdr(skb)->h_dest))
- return false;
-
- /* Don't respond to L3 broadcast or invalid addresses. */
- if (!check_ipv4_address(old_iph->daddr) ||
- !check_ipv4_address(old_iph->saddr))
- return false;
-
- /* Only respond to the first fragment. */
- if (old_iph->frag_off & htons(IP_OFFSET))
- return false;
-
- /* Don't respond to ICMP error messages. */
- if (old_iph->protocol == IPPROTO_ICMP) {
- u8 icmp_type, *icmp_typep;
-
- icmp_typep = skb_header_pointer(skb, (u8 *)old_iph +
- (old_iph->ihl << 2) +
- offsetof(struct icmphdr, type) -
- skb->data, sizeof(icmp_type),
- &icmp_type);
-
- if (!icmp_typep)
- return false;
-
- if (*icmp_typep > NR_ICMP_TYPES
- || (*icmp_typep <= ICMP_PARAMETERPROB
- && *icmp_typep != ICMP_ECHOREPLY
- && *icmp_typep != ICMP_ECHO))
- return false;
- }
-
- return true;
-}
-
-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;
-}