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app/testpmd: fix reply to a multicast ICMP request

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Set the IP source and destination addresses in the IP header of the
ICMP reply as follows:
  - Use the request IP source address as the reply IP destination address
  - If the request IP destination address is a multicast IP address
      - choose a reply IP source address different from the request IP
        source address,
      - re-compute the IP header checksum.
    Otherwise
      - switch the request IP source and destination addresses in the
        reply,
      - keep the IP header checksum unchanged.

Signed-off-by: Ivan Boule <ivan.boule@6wind.com>
This commit is contained in:
Ivan Boule 2015-05-28 17:05:23 +02:00 committed by Thomas Monjalon
parent d4f891b5fc
commit 8443ce8193
1 changed files with 50 additions and 4 deletions
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54
app/test-pmd/icmpecho.c
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@ -272,6 +272,30 @@ ipv4_addr_dump(const char *what, uint32_t be_ipv4_addr)
printf("%s", buf);
}
static uint16_t
ipv4_hdr_cksum(struct ipv4_hdr *ip_h)
{
uint16_t *v16_h;
uint32_t ip_cksum;
/*
* Compute the sum of successive 16-bit words of the IPv4 header,
* skipping the checksum field of the header.
*/
v16_h = (uint16_t *) ip_h;
ip_cksum = v16_h[0] + v16_h[1] + v16_h[2] + v16_h[3] +
v16_h[4] + v16_h[6] + v16_h[7] + v16_h[8] + v16_h[9];
/* reduce 32 bit checksum to 16 bits and complement it */
ip_cksum = (ip_cksum & 0xffff) + (ip_cksum >> 16);
ip_cksum = (ip_cksum & 0xffff) + (ip_cksum >> 16);
ip_cksum = (~ip_cksum) & 0x0000FFFF;
return (ip_cksum == 0) ? 0xFFFF : (uint16_t) ip_cksum;
}
#define is_multicast_ipv4_addr(ipv4_addr) \
(((rte_be_to_cpu_32((ipv4_addr)) >> 24) & 0x000000FF) == 0xE0)
/*
* Receive a burst of packets, lookup for ICMP echo requets, and, if any,
* send back ICMP echo replies.
@ -443,9 +467,18 @@ reply_to_icmp_echo_rqsts(struct fwd_stream *fs)
/*
* Prepare ICMP echo reply to be sent back.
* - switch ethernet source and destinations addresses,
* - switch IPv4 source and destinations addresses,
* - use the request IP source address as the reply IP
* destination address,
* - if the request IP destination address is a multicast
* address:
* - choose a reply IP source address different from the
* request IP source address,
* - re-compute the IP header checksum.
* Otherwise:
* - switch the request IP source and destination
* addresses in the reply IP header,
* - keep the IP header checksum unchanged.
* - set IP_ICMP_ECHO_REPLY in ICMP header.
* No need to re-compute the IP header checksum.
* ICMP checksum is computed by assuming it is valid in the
* echo request and not verified.
*/
@ -453,8 +486,21 @@ reply_to_icmp_echo_rqsts(struct fwd_stream *fs)
ether_addr_copy(&eth_h->d_addr, &eth_h->s_addr);
ether_addr_copy(&eth_addr, &eth_h->d_addr);
ip_addr = ip_h->src_addr;
ip_h->src_addr = ip_h->dst_addr;
ip_h->dst_addr = ip_addr;
if (is_multicast_ipv4_addr(ip_h->dst_addr)) {
uint32_t ip_src;
ip_src = rte_be_to_cpu_32(ip_addr);
if ((ip_src & 0x00000003) == 1)
ip_src = (ip_src & 0xFFFFFFFC) | 0x00000002;
else
ip_src = (ip_src & 0xFFFFFFFC) | 0x00000001;
ip_h->src_addr = rte_cpu_to_be_32(ip_src);
ip_h->dst_addr = ip_addr;
ip_h->hdr_checksum = ipv4_hdr_cksum(ip_h);
} else {
ip_h->src_addr = ip_h->dst_addr;
ip_h->dst_addr = ip_addr;
}
icmp_h->icmp_type = IP_ICMP_ECHO_REPLY;
cksum = ~icmp_h->icmp_cksum & 0xffff;
cksum += ~htons(IP_ICMP_ECHO_REQUEST << 8) & 0xffff;