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Extend packet dump system to RA.

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This commit is contained in:
Simon Kelley
2022-01-29 22:52:21 +00:00
parent fc664d114d
commit b5dafc0b7e
4 changed files with 86 additions and 25 deletions
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88
src/dump.c
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@@ -18,6 +18,8 @@
#ifdef HAVE_DUMPFILE
#include <netinet/icmp6.h>
static u32 packet_count;
/* https://wiki.wireshark.org/Development/LibpcapFileFormat */
@@ -79,8 +81,9 @@ void dump_init(void)
}
}
/* port == -1 ->ICMPv6 */
void dump_packet(int mask, void *packet, size_t len,
union mysockaddr *src, union mysockaddr *dst, unsigned short port)
union mysockaddr *src, union mysockaddr *dst, int port)
{
struct ip ip;
struct ip6_hdr ip6;
@@ -116,10 +119,19 @@ void dump_packet(int mask, void *packet, size_t len,
memset(&ip6, 0, sizeof(ip6));
ip6.ip6_vfc = 6 << 4;
ip6.ip6_plen = htons(sizeof(struct udphdr) + len);
ip6.ip6_nxt = IPPROTO_UDP;
ip6.ip6_hops = 64;
if (port == -1)
{
ip6.ip6_plen = htons(len);
ip6.ip6_nxt = IPPROTO_ICMPV6;
}
else
{
ip6.ip6_plen = htons(sizeof(struct udphdr) + len);
ip6.ip6_nxt = IPPROTO_UDP;
}
if (src)
{
memcpy(&ip6.ip6_src, &src->in6.sin6_addr, IN6ADDRSZ);
@@ -137,7 +149,6 @@ void dump_packet(int mask, void *packet, size_t len,
{
sum += ip6.ip6_src.s6_addr[i] + (ip6.ip6_src.s6_addr[i+1] << 8) ;
sum += ip6.ip6_dst.s6_addr[i] + (ip6.ip6_dst.s6_addr[i+1] << 8) ;
}
}
else
@@ -148,9 +159,18 @@ void dump_packet(int mask, void *packet, size_t len,
ip.ip_v = IPVERSION;
ip.ip_hl = sizeof(struct ip) / 4;
ip.ip_len = htons(sizeof(struct ip) + sizeof(struct udphdr) + len);
ip.ip_ttl = IPDEFTTL;
ip.ip_p = IPPROTO_UDP;
if (port == -1)
{
ip.ip_len = htons(sizeof(struct ip) + len);
ip.ip_p = IPPROTO_ICMP;
}
else
{
ip.ip_len = htons(sizeof(struct ip) + sizeof(struct udphdr) + len);
ip.ip_p = IPPROTO_UDP;
}
if (src)
{
@@ -181,31 +201,59 @@ void dump_packet(int mask, void *packet, size_t len,
if (len & 1)
((unsigned char *)packet)[len] = 0; /* for checksum, in case length is odd. */
udp.uh_sum = 0;
udp.uh_ulen = htons(sizeof(struct udphdr) + len);
sum += htons(IPPROTO_UDP);
sum += htons(sizeof(struct udphdr) + len);
for (i = 0; i < sizeof(struct udphdr)/2; i++)
sum += ((u16 *)&udp)[i];
for (i = 0; i < (len + 1) / 2; i++)
sum += ((u16 *)packet)[i];
while (sum >> 16)
sum = (sum & 0xffff) + (sum >> 16);
udp.uh_sum = (sum == 0xffff) ? sum : ~sum;
if (port == -1)
{
/* ICMP - ICMPv6 packet is a superset of ICMP */
struct icmp6_hdr *icmp = packet;
/* See comment in UDP code below. */
sum += htons(family == AF_INET6 ? IPPROTO_ICMPV6 : IPPROTO_ICMP);
sum += htons(len);
icmp->icmp6_cksum = 0;
for (i = 0; i < (len + 1) / 2; i++)
sum += ((u16 *)packet)[i];
while (sum >> 16)
sum = (sum & 0xffff) + (sum >> 16);
icmp->icmp6_cksum = (sum == 0xffff) ? sum : ~sum;
pcap_header.incl_len = pcap_header.orig_len = ipsz + len;
}
else
{
/* Add Remaining part of the pseudoheader. Note that though the
IPv6 pseudoheader is very different to the IPv4 one, the
net result of this calculation is correct as long as the
packet length is less than 65536, which is fine for us. */
sum += htons(IPPROTO_UDP);
sum += htons(sizeof(struct udphdr) + len);
udp.uh_sum = 0;
udp.uh_ulen = htons(sizeof(struct udphdr) + len);
for (i = 0; i < sizeof(struct udphdr)/2; i++)
sum += ((u16 *)&udp)[i];
for (i = 0; i < (len + 1) / 2; i++)
sum += ((u16 *)packet)[i];
while (sum >> 16)
sum = (sum & 0xffff) + (sum >> 16);
udp.uh_sum = (sum == 0xffff) ? sum : ~sum;
pcap_header.incl_len = pcap_header.orig_len = ipsz + sizeof(udp) + len;
}
rc = gettimeofday(&time, NULL);
pcap_header.ts_sec = time.tv_sec;
pcap_header.ts_usec = time.tv_usec;
pcap_header.incl_len = pcap_header.orig_len = ipsz + sizeof(udp) + len;
if (rc == -1 ||
!read_write(daemon->dumpfd, (void *)&pcap_header, sizeof(pcap_header), 0) ||
!read_write(daemon->dumpfd, iphdr, ipsz, 0) ||
!read_write(daemon->dumpfd, (void *)&udp, sizeof(udp), 0) ||
(port != -1 && !read_write(daemon->dumpfd, (void *)&udp, sizeof(udp), 0)) ||
!read_write(daemon->dumpfd, (void *)packet, len, 0))
my_syslog(LOG_ERR, _("failed to write packet dump"));
else
my_syslog(LOG_INFO, _("dumping UDP packet %u mask 0x%04x"), ++packet_count, mask);
my_syslog(LOG_INFO, _("dumping packet %u mask 0x%04x"), ++packet_count, mask);
}