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Native decode TCP options, log new TCP sessions

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This commit is contained in:
M66B 2016-02-11 15:44:31 +01:00
parent 31b0b8e7ad
commit bbb99e00b6
1 changed files with 26 additions and 1 deletions
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27
app/src/main/jni/netguard/tcp.c
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@ -349,6 +349,7 @@ jboolean handle_tcp(const struct arguments *args,
const struct ip6_hdr *ip6 = (struct ip6_hdr *) pkt;
const struct tcphdr *tcphdr = (struct tcphdr *) payload;
const uint8_t tcpoptlen = (uint8_t) ((tcphdr->doff - 5) * 4);
const uint8_t *tcpoptions = payload + sizeof(struct tcphdr);
const uint8_t *data = payload + sizeof(struct tcphdr) + tcpoptlen;
const uint16_t datalen = (const uint16_t) (length - (data - pkt));
@ -404,7 +405,31 @@ jboolean handle_tcp(const struct arguments *args,
// Check session
if (cur == NULL) {
if (tcphdr->syn) {
log_android(ANDROID_LOG_INFO, "%s new session", packet);
// Decode options
// http://www.iana.org/assignments/tcp-parameters/tcp-parameters.xhtml#tcp-parameters-1
uint16_t mss = 0;
int optlen = tcpoptlen;
uint8_t *options = tcpoptions;
while (optlen > 0) {
uint8_t kind = *options;
uint8_t len = *(options + 1);
if (kind == 0) // End of options list
break;
if (kind == 2)
mss = ntohs(*((uint16_t *) (options + 2)));
if (kind == 1) {
optlen--;
options++;
}
else {
optlen -= len;
options += len;
}
}
log_android(ANDROID_LOG_WARN, "%s new session mss %d", packet, mss);
// Register session
struct tcp_session *syn = malloc(sizeof(struct tcp_session));