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Add IPv6 support for root capture

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This commit is contained in:
emanuele-f 2021-06-30 12:13:00 +02:00
parent ca7c8127d9
commit 334e84fa3d
1 changed files with 61 additions and 9 deletions
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70
app/src/main/jni/pcapd/pcapd.c
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@ -66,6 +66,7 @@ typedef struct {
char ifname[IFNAMSIZ];
uint64_t mac;
uint32_t ip;
struct in6_addr ip6;
char nlbuf[8192]; /* >= 8192 to avoid truncation, see "man 7 netlink" */
} pcapd_runtime_t;
@ -157,6 +158,41 @@ static int get_iface_ip(const char *iface, uint32_t *ip, uint32_t *netmask) {
/* ******************************************************* */
static int get_iface_ip6(const char *iface, struct in6_addr *ip) {
FILE *f = fopen("/proc/net/if_inet6", "r");
char line[128];
int found = 0;
if(f == NULL)
return -1;
__be32 *ip6 = ip->in6_u.u6_addr32;
while(fgets(line, sizeof(line), f)) {
if((strstr(line, iface) != NULL) &&
(sscanf(line, "%08x%08x%08x%08x", &ip6[0], &ip6[1], &ip6[2], &ip6[3]) == 4)) {
for(int i=0; i<4; i++)
ip6[i] = htonl(ip6[i]);
if((ip->in6_u.u6_addr8[0] == 0xfe) &&
((ip->in6_u.u6_addr8[1] & 0xC0) == 0x80)) // link local address
continue;
char addr[INET6_ADDRSTRLEN];
inet_ntop(AF_INET6, ip, addr, INET6_ADDRSTRLEN);
log_d("IPv6 address[%s]: %s", iface, addr);
found = 1;
break;
}
}
fclose(f);
return(found ? 0 : -1);
}
/* ******************************************************* */
static int list_interfaces() {
pcap_if_t *devs, *pd;
@ -241,7 +277,8 @@ static int init_pcapd_capture(pcapd_runtime_t *rt) {
return -1;
}
rt->nlsock = nl_socket(RTMGRP_IPV4_ROUTE | RTMGRP_IPV4_IFADDR | RTMGRP_IPV4_RULE); // TODO IPv6
rt->nlsock = nl_socket(RTMGRP_IPV4_ROUTE | RTMGRP_IPV4_IFADDR | RTMGRP_IPV4_RULE |
RTMGRP_IPV6_ROUTE | RTMGRP_IPV6_IFADDR);
if(rt->nlsock < 0) {
log_e("could not create netlink socket[%d]: %s", errno, strerror(errno));
@ -338,7 +375,7 @@ static void check_capture_interface(pcapd_runtime_t *rt) {
struct bpf_program fcode;
// Only IP traffic
if(pcap_compile(pd, &fcode, "ip", 1, PCAP_NETMASK_UNKNOWN) < 0) {
if(pcap_compile(pd, &fcode, "ip or ip6", 1, PCAP_NETMASK_UNKNOWN) < 0) {
log_i("[%s] could not set capture filter: %s", ifname, pcap_geterr(pd));
pcap_close(pd);
return;
@ -360,12 +397,17 @@ static void check_capture_interface(pcapd_runtime_t *rt) {
rt->mac = 0;
if((dlink == DLT_EN10MB) && (get_iface_mac(ifname, &rt->mac) < 0))
log_i("Could not get interface %s MAC[%d]: %s", ifname, errno, strerror(errno));
log_i("Could not get interface %s MAC[%d]: %s", ifname, errno, strerror(errno));
uint32_t netmask;
rt->ip = 0;
if(get_iface_ip(ifname, &rt->ip, &netmask) < 0)
log_i("Could not get interface %s IP[%d]: %s", ifname, errno, strerror(errno));
log_i("Could not get interface %s IP[%d]: %s", ifname, errno, strerror(errno));
if(get_iface_ip6(ifname, &rt->ip6) < 0) {
log_i("Could not get interface %s IPv6[%d]: %s", ifname, errno, strerror(errno));
memset(&rt->ip6, 0, sizeof(rt->ip6));
}
rt->dlink = dlink;
rt->ipoffset = ipoffset;
@ -424,6 +466,11 @@ static int handle_nl_message(pcapd_runtime_t *rt) {
if(get_iface_ip(rt->ifname, &rt->ip, &netmask) < 0)
log_i("Could not get interface %s IP[%d]: %s", rt->ifname, errno, strerror(errno));
if(get_iface_ip6(rt->ifname, &rt->ip6) < 0) {
log_i("Could not get interface %s IPv6[%d]: %s", rt->ifname, errno, strerror(errno));
memset(&rt->ip6, 0, sizeof(rt->ip6));
}
break;
}
break;
@ -472,16 +519,21 @@ static int is_tx_packet(pcapd_runtime_t *rt, const u_char *pkt, u_int16_t len) {
pkt += SLL_HDR_LEN;
}
// NOTE: this must be IP traffic due to the PCAP filter
// NOTE: this must be IPv4/IPv6 traffic due to the PCAP filter
if(len < 20)
return 0;
struct iphdr *ip = (struct iphdr *) pkt;
if(ip->version != 4) // TODO IPv6 support
return 0;
if(ip->saddr == rt->ip)
return 1; // TX
if(ip->version == 4) {
if(ip->daddr == rt->ip)
return 0; // RX
} else if(ip->version == 6) {
struct ipv6hdr *hdr = (struct ipv6hdr *) pkt;
if(memcmp(&hdr->daddr, &rt->ip6, sizeof(rt->ip6)) == 0)
return 0; // RX
}
return 1; // by default assume TX
}