From 89864c330cc2d9c87f09c06454b18112f972ec54 Mon Sep 17 00:00:00 2001
From: Daniel Adolfsson <daniel@ashen.se>
Date: Wed, 11 Dec 2019 13:44:55 +0100
Subject: [PATCH] More work on updating sessions

---
 src/iface.c   | 11 ++++++++---
 src/proxy.c   | 23 ++++++++++++++++-------
 src/session.h |  5 +++--
 3 files changed, 27 insertions(+), 12 deletions(-)

diff --git a/src/iface.c b/src/iface.c
index 8ca798d..1d1c443 100644
--- a/src/iface.c
+++ b/src/iface.c
@@ -93,9 +93,14 @@ static void ndL_handle_na(nd_iface_t *iface, ndL_icmp6_msg_t *msg)
     if (!session)
         return;
 
-    session->state = ND_STATE_VALID;
-    session->mtime = nd_current_time;
-    nd_log_debug("session [%s] %s INVALID -> (deleted)", "?", nd_addr_to_string(&session->tgt));
+    if (session->state != ND_STATE_VALID)
+    {
+        session->state = ND_STATE_VALID;
+        session->mtime = nd_current_time;
+        nd_log_debug("session [%s] %s ? -> VALID", "?", nd_addr_to_string(&session->tgt));
+    }
+
+    session->atime = nd_current_time;
 }
 
 static uint16_t ndL_calculate_checksum(uint32_t sum, const void *data, size_t length)
diff --git a/src/proxy.c b/src/proxy.c
index 33bfeb6..f691437 100644
--- a/src/proxy.c
+++ b/src/proxy.c
@@ -78,6 +78,7 @@ void nd_proxy_handle_ns(nd_proxy_t *proxy, nd_addr_t *src, __attribute__((unused
 
         if (session->state == ND_STATE_VALID || session->state == ND_STATE_STALE)
         {
+            session->atime = nd_current_time;
             nd_iface_write_na(proxy->iface, src, src_ll, tgt, proxy->router);
             return;
         }
@@ -95,11 +96,13 @@ void nd_proxy_handle_ns(nd_proxy_t *proxy, nd_addr_t *src, __attribute__((unused
         return;
 
     session = nd_alloc_session();
-    session->mtime = nd_current_time;
-    session->tgt = *tgt;
-
     ND_LL_PREPEND(proxy->sessions, session, next_in_proxy);
 
+    session->mtime = nd_current_time;
+    session->atime = nd_current_time;
+    session->rtime = nd_current_time;
+    session->tgt = *tgt;
+
     if (rule->is_auto)
     {
         /* TODO: Loop through valid routes. */
@@ -128,6 +131,7 @@ void nd_proxy_handle_ns(nd_proxy_t *proxy, nd_addr_t *src, __attribute__((unused
     if (session->iface)
     {
         session->state = ND_STATE_INCOMPLETE;
+        session->rcount = 0;
         nd_iface_write_ns(session->iface, tgt);
 
         ND_LL_PREPEND(session->iface->sessions, session, next_in_iface);
@@ -193,11 +197,16 @@ static void ndL_update_session(nd_proxy_t *proxy, nd_session_t *session)
         }
         else
         {
-            long t = session->rcount && !(session->rcount % nd_conf_retrans_limit)
-                         ? ((1 << session->rcount / 3) * nd_conf_retrans_time)
-                         : nd_conf_retrans_time;
+            /* We will only retransmit if nd_conf_keepalive is true, or if the last incoming NS
+             * request was made less than nd_conf_valid_ttl milliseconds ago. */
+            if (!nd_conf_keepalive && nd_current_time - session->atime > nd_conf_valid_ttl)
+                break;
 
-            if (nd_current_time - session->rtime < t)
+            long time = session->rcount && !(session->rcount % nd_conf_retrans_limit)
+                            ? ((1 << session->rcount / 3) * nd_conf_retrans_time)
+                            : nd_conf_retrans_time;
+
+            if (nd_current_time - session->rtime < time)
                 break;
 
             session->rcount++;
diff --git a/src/session.h b/src/session.h
index 305c22b..756c27e 100644
--- a/src/session.h
+++ b/src/session.h
@@ -52,8 +52,9 @@ struct nd_session
     nd_session_t *next_in_iface;
     nd_addr_t tgt;
     int rcount;
-    long rtime;
-    long mtime;
+    long atime; /* Last time the session was used in a NA response. */
+    long rtime; /* Last time a NS request was made. */
+    long mtime; /* Last time state was changed. */
     nd_state_t state;
     nd_iface_t *iface;
 };