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Implement connection status detection in root mode

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This commit is contained in:
emanuele-f 2021-07-06 17:30:15 +02:00
parent bc28244e21
commit 8d7f3d7777
2 changed files with 71 additions and 6 deletions
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72
app/src/main/jni/vpnproxy-jni/capture_root.c
View File

@ -190,6 +190,59 @@ static int connectPcapd(vpnproxy_data_t *proxy) {
/* ******************************************************* */
// Determines when a connection gets closed
static void update_connection_status(pcap_conn_t *conn, zdtun_pkt_t *pkt, uint8_t dir) {
if((conn->data->status >= CONN_STATUS_CLOSED) || (pkt->flags & ZDTUN_PKT_IS_FRAGMENT))
return;
if(conn->tuple.ipproto == IPPROTO_TCP) {
struct tcphdr *tcp = pkt->tcp;
conn->data->tcp_flags[dir] |= tcp->th_flags;
uint8_t seen_flags = conn->data->tcp_flags[0] | conn->data->tcp_flags[1];
if(tcp->th_flags & TH_RST)
conn->data->status = CONN_STATUS_RESET;
else if(seen_flags & TCP_FLAG_FIN) {
// closed when both the peers have sent FIN and the last FIN was acknowledged
if(!conn->data->last_ack)
conn->data->last_ack = true; // wait for the last ACK
else if(tcp->th_flags & TH_ACK)
conn->data->status = CONN_STATUS_CLOSED;
} else if(conn->data->status < CONN_STATUS_CONNECTED) {
const uint8_t syn_ack_flags = TCP_FLAG_SYN | TCP_FLAG_ACK;
// the 3-way-handshake is complete when both the peers have sent the SYN+ACK flags
if((pkt->l7_len > 0) ||
((seen_flags & syn_ack_flags) == syn_ack_flags))
conn->data->status = CONN_STATUS_CONNECTED;
else
conn->data->status = CONN_STATUS_CONNECTING;
}
} else {
if(conn->data->status < CONN_STATUS_CONNECTED)
conn->data->status = CONN_STATUS_CONNECTED;
if((conn->tuple.ipproto == IPPROTO_UDP) &&
pkt->l7_len >= sizeof(struct dns_packet) &&
(conn->tuple.dst_port == ntohs(53))) {
const dns_packet_t *dns = (dns_packet_t *)pkt->l7;
if((dns->flags & DNS_FLAGS_MASK) == DNS_TYPE_REQUEST)
conn->data->pending_dns_queries++;
else if((dns->flags & DNS_FLAGS_MASK) == DNS_TYPE_RESPONSE) {
conn->data->pending_dns_queries--;
// Close the connection as soon as all the responses arrive
if(conn->data->pending_dns_queries == 0)
conn->data->status = CONN_STATUS_CLOSED;
}
}
}
}
/* ******************************************************* */
static void handle_packet(vpnproxy_data_t *proxy, pcap_conn_t **connections, pcapd_hdr_t *hdr, const char *buffer) {
zdtun_pkt_t pkt;
pcap_conn_t *conn = NULL;
@ -252,9 +305,6 @@ static void handle_packet(vpnproxy_data_t *proxy, pcap_conn_t **connections, pca
conn->tuple = pkt.tuple;
conn->data = data;
// TODO read from linux?
data->status = CONN_STATUS_CONNECTED;
HASH_ADD(hh, *connections, tuple, sizeof(zdtun_5tuple_t), conn);
data->incr_id = proxy->incr_id++;
@ -281,6 +331,14 @@ static void handle_packet(vpnproxy_data_t *proxy, pcap_conn_t **connections, pca
uint64_t pkt_ms = (uint64_t)hdr->ts.tv_sec * 1000 + hdr->ts.tv_usec / 1000;
account_packet(proxy, &pkt, from_tun, &conn->tuple, conn->data, pkt_ms);
update_connection_status(conn, &pkt, !from_tun);
if(conn->data->status >= CONN_STATUS_CLOSED) {
// Will free the data in sendConnectionsDump
HASH_DELETE(hh, *connections, conn);
free(conn);
}
}
/* ******************************************************* */
@ -292,7 +350,6 @@ static void purge_expired_connections(vpnproxy_data_t *proxy, pcap_conn_t **conn
HASH_ITER(hh, *connections, conn, tmp) {
uint64_t timeout = 0;
// TODO: sync with linux?
switch(conn->tuple.ipproto) {
case IPPROTO_TCP:
timeout = TCP_TIMEOUT_SEC * 1000;
@ -305,14 +362,17 @@ static void purge_expired_connections(vpnproxy_data_t *proxy, pcap_conn_t **conn
break;
}
if(purge_all || (conn->data->status >= CONN_STATUS_CLOSED) || (last_pkt_ms >= (conn->data->last_seen + timeout))) {
if(purge_all
|| (conn->data->status >= CONN_STATUS_CLOSED)
|| (last_pkt_ms >= (conn->data->last_seen + timeout))) {
log_d("IDLE (type=%d)", conn->tuple.ipproto);
// Will free the data in sendConnectionsDump
conn->data->update_type |= CONN_UPDATE_STATS;
notify_connection(&proxy->conns_updates, &conn->tuple, conn->data);
conn->data->status = CONN_STATUS_CLOSED;
if(conn->data->status < CONN_STATUS_CLOSED)
conn->data->status = CONN_STATUS_CLOSED;
switch (conn->tuple.ipproto) {
case IPPROTO_TCP:

5
app/src/main/jni/vpnproxy-jni/vpnproxy.h
View File

@ -73,6 +73,11 @@ typedef struct conn_data {
zdtun_conn_status_t status;
char *info;
jint uid;
uint8_t tcp_flags[2]; // cli2srv, srv2cli
union {
uint8_t last_ack;
uint8_t pending_dns_queries;
};
bool pending_notification;
bool request_done;
char *request_data;