From fa4fdb1e1b950ea97902bc0b0522c0aaa4cf2300 Mon Sep 17 00:00:00 2001
From: emanuele-f <black.silver@hotmail.it>
Date: Tue, 6 Jul 2021 18:27:26 +0200
Subject: [PATCH] Delay closed connections free with root

This prevents creating a new connection on packets retransmissions
---
 app/src/main/jni/vpnproxy-jni/capture_proxy.c |  4 +++
 app/src/main/jni/vpnproxy-jni/capture_root.c  | 30 +++++++++----------
 app/src/main/jni/vpnproxy-jni/vpnproxy.c      |  2 +-
 app/src/main/jni/vpnproxy-jni/vpnproxy.h      |  1 +
 4 files changed, 21 insertions(+), 16 deletions(-)

diff --git a/app/src/main/jni/vpnproxy-jni/capture_proxy.c b/app/src/main/jni/vpnproxy-jni/capture_proxy.c
index 36c28053..42d3fc88 100644
--- a/app/src/main/jni/vpnproxy-jni/capture_proxy.c
+++ b/app/src/main/jni/vpnproxy-jni/capture_proxy.c
@@ -240,6 +240,7 @@ static void destroy_connection(zdtun_t *tun, const zdtun_conn_t *conn_info) {
         notify_connection(&proxy->conns_updates, tuple, data);
 
         data->status = zdtun_conn_get_status(conn_info);
+        data->to_purge = true;
     } else
         conn_free_data(data);
 }
@@ -284,6 +285,9 @@ static void on_packet(zdtun_t *tun, const zdtun_pkt_t *pkt, uint8_t from_tun, co
     }
 
     account_packet(proxy, pkt, from_tun, tuple, data, pkt_ms);
+
+    if(data->status >= CONN_STATUS_CLOSED)
+        data->to_purge = true;
 }
 
 /* ******************************************************* */
diff --git a/app/src/main/jni/vpnproxy-jni/capture_root.c b/app/src/main/jni/vpnproxy-jni/capture_root.c
index 01f424b3..ff5b848d 100644
--- a/app/src/main/jni/vpnproxy-jni/capture_root.c
+++ b/app/src/main/jni/vpnproxy-jni/capture_root.c
@@ -27,6 +27,7 @@
 // Keep in sync with zdtun.c
 #define ICMP_TIMEOUT_SEC 5
 #define UDP_TIMEOUT_SEC 30
+#define TCP_CLOSED_TIMEOUT_SEC 15
 #define TCP_TIMEOUT_SEC 60
 
 /* ******************************************************* */
@@ -333,12 +334,6 @@ static void handle_packet(vpnproxy_data_t *proxy, pcap_conn_t **connections, pca
     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);
-    }
 }
 
 /* ******************************************************* */
@@ -352,7 +347,7 @@ static void purge_expired_connections(vpnproxy_data_t *proxy, pcap_conn_t **conn
 
         switch(conn->tuple.ipproto) {
             case IPPROTO_TCP:
-                timeout = TCP_TIMEOUT_SEC * 1000;
+                timeout = (conn->data->status >= CONN_STATUS_CLOSED) ? (TCP_CLOSED_TIMEOUT_SEC * 1000) : (TCP_TIMEOUT_SEC * 1000);
                 break;
             case IPPROTO_UDP:
                 timeout = UDP_TIMEOUT_SEC * 1000;
@@ -362,17 +357,22 @@ 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))) {
-            log_d("IDLE (type=%d)", conn->tuple.ipproto);
+        if(purge_all || (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);
+            // The connection data will be purged
+            conn->data->to_purge = true;
 
-            if(conn->data->status < CONN_STATUS_CLOSED)
+            if(conn->data->status < CONN_STATUS_CLOSED) {
                 conn->data->status = CONN_STATUS_CLOSED;
+                conn->data->update_type |= CONN_UPDATE_STATS;
+            }
+
+            if(conn->data->update_type != 0) {
+                // Will free the data in sendConnectionsDump
+                notify_connection(&proxy->conns_updates, &conn->tuple, conn->data);
+            } else
+                conn_free_data(conn->data);
 
             switch (conn->tuple.ipproto) {
                 case IPPROTO_TCP:
diff --git a/app/src/main/jni/vpnproxy-jni/vpnproxy.c b/app/src/main/jni/vpnproxy-jni/vpnproxy.c
index 90a8d91d..f439a1ad 100644
--- a/app/src/main/jni/vpnproxy-jni/vpnproxy.c
+++ b/app/src/main/jni/vpnproxy-jni/vpnproxy.c
@@ -106,7 +106,7 @@ static void conns_clear(conn_array_t *arr, bool free_all) {
         for(int i=0; i < arr->cur_items; i++) {
             vpn_conn_t *slot = &arr->items[i];
 
-            if(slot->data && ((slot->data->status >= CONN_STATUS_CLOSED) || free_all))
+            if(slot->data && (slot->data->to_purge || free_all))
                 conn_free_data(slot->data);
         }
 
diff --git a/app/src/main/jni/vpnproxy-jni/vpnproxy.h b/app/src/main/jni/vpnproxy-jni/vpnproxy.h
index 263ce09d..8107c01d 100644
--- a/app/src/main/jni/vpnproxy-jni/vpnproxy.h
+++ b/app/src/main/jni/vpnproxy-jni/vpnproxy.h
@@ -79,6 +79,7 @@ typedef struct conn_data {
         uint8_t pending_dns_queries;
     };
     bool pending_notification;
+    bool to_purge;
     bool request_done;
     char *request_data;
     char *url;