net/tcp: Use the relative value for keep alive timer

unify the timer process logic as other tcp state

Signed-off-by: Xiang Xiao <xiaoxiang@xiaomi.com>

net/tcp/tcp.h

@@ -284,9 +284,7 @@ struct tcp_conn_s
    * system clock tick.
    */
 
-  clock_t    keeptime;    /* Last time that the TCP socket was known to be
+  uint32_t   keeptimer;   /* KeepAlive timer (dsec) */
-                           * alive (ACK or data received) OR time that the
-                           * last probe was sent. */
   uint32_t   keepidle;    /* Elapsed idle time before first probe sent (dsec) */
   uint32_t   keepintvl;   /* Interval between probes (dsec) */
   bool       keepalive;   /* True: KeepAlive enabled; false: disabled */

net/tcp/tcp_conn.c

@@ -727,7 +727,6 @@ FAR struct tcp_conn_s *tcp_alloc(uint8_t domain)
       conn->domain        = domain;
 #endif
 #ifdef CONFIG_NET_TCP_KEEPALIVE
-      conn->keeptime      = clock_systime_ticks();
       conn->keepidle      = 2 * DSEC_PER_HOUR;
       conn->keepintvl     = 2 * DSEC_PER_SEC;
       conn->keepcnt       = 3;

net/tcp/tcp_getsockopt.c

@@ -132,7 +132,7 @@ int tcp_getsockopt(FAR struct socket *psock, int option,
         else
           {
             FAR int *keepalive = (FAR int *)value;
-            *keepalive         = (int)conn->keepalive;
+            *keepalive         = conn->keepalive;
             *value_len         = sizeof(int);
             ret                = OK;
           }
@@ -216,7 +216,7 @@ int tcp_getsockopt(FAR struct socket *psock, int option,
         else
           {
             FAR int *keepcnt = (FAR int *)value;
-            *keepcnt         = (int)conn->keepcnt;
+            *keepcnt         = conn->keepcnt;
             *value_len       = sizeof(int);
             ret              = OK;
           }

net/tcp/tcp_input.c

@@ -1143,13 +1143,9 @@ found:
         if (conn->keepalive &&
             (dev->d_len > 0 || (tcp->flags & TCP_ACK) != 0))
           {
-            /* Reset the last known "alive" time.
+            /* Reset the "alive" timer. */
-             *
-             * REVISIT:  At this level, we don't actually know if keep-
-             * alive is enabled for this connection.
-             */
 
-            conn->keeptime    = clock_systime_ticks();
+            conn->keeptimer   = conn->keepidle;
             conn->keepretries = 0;
           }
 #endif

net/tcp/tcp_setsockopt.c

@@ -78,7 +78,7 @@ int tcp_setsockopt(FAR struct socket *psock, int option,
    */
 
   FAR struct tcp_conn_s *conn;
-  int ret;
+  int ret = OK;
 
   DEBUGASSERT(psock != NULL && value != NULL && psock->s_conn != NULL);
   conn = (FAR struct tcp_conn_s *)psock->s_conn;
@@ -107,8 +107,8 @@ int tcp_setsockopt(FAR struct socket *psock, int option,
        * all of the clones that may use the underlying connection.
        */
 
-      case SO_KEEPALIVE:  /* Verifies TCP connections active by enabling the
+      case SO_KEEPALIVE: /* Verifies TCP connections active by enabling the
-                           * periodic transmission of probes */
+                          * periodic transmission of probes */
         if (value_len != sizeof(int))
           {
             ret = -EDOM;
@@ -125,9 +125,15 @@ int tcp_setsockopt(FAR struct socket *psock, int option,
               }
             else
               {
-                conn->keepalive = (bool)keepalive;
+                conn->keepalive = keepalive;
-                conn->keeptime  = clock_systime_ticks();   /* Reset start time */
+
-                ret = OK;
+                /* Reset timer */
+
+                if (conn->keepalive)
+                  {
+                    conn->keeptimer   = conn->keepidle;
+                    conn->keepretries = 0;
+                  }
               }
           }
         break;
@@ -141,11 +147,7 @@ int tcp_setsockopt(FAR struct socket *psock, int option,
           {
             int nodelay = *(FAR int *)value;
 
-            if (nodelay)
+            if (!nodelay)
-              {
-                ret = OK;
-              }
-            else
               {
                 nerr("ERROR: TCP_NODELAY not supported\n");
                 ret = -ENOSYS;
@@ -170,7 +172,7 @@ int tcp_setsockopt(FAR struct socket *psock, int option,
                * be forced to the next larger, whole decisecond value.
                */
 
-              dsecs = (socktimeo_t)net_timeval2dsec(tv, TV2DS_CEIL);
+              dsecs = net_timeval2dsec(tv, TV2DS_CEIL);
             }
           else if (value_len == sizeof(int))
             {
@@ -189,20 +191,24 @@ int tcp_setsockopt(FAR struct socket *psock, int option,
 
           if (option == TCP_KEEPIDLE)
             {
-              conn->keepidle = (uint16_t)dsecs;
+              conn->keepidle = dsecs;
             }
           else
             {
-              conn->keepintvl = (uint16_t)dsecs;
+              conn->keepintvl = dsecs;
             }
 
-          conn->keeptime  = clock_systime_ticks();   /* Reset start time */
+           /* Reset timer */
 
-          ret = OK;
+          if (conn->keepalive)
+            {
+              conn->keeptimer   = conn->keepidle;
+              conn->keepretries = 0;
+            }
         }
         break;
 
-      case TCP_KEEPCNT:   /* Number of keepalives before death */
+      case TCP_KEEPCNT: /* Number of keepalives before death */
         if (value_len != sizeof(int))
           {
             ret = -EDOM;
@@ -218,9 +224,15 @@ int tcp_setsockopt(FAR struct socket *psock, int option,
               }
             else
               {
-                conn->keepcnt  = (uint8_t)keepcnt;
+                conn->keepcnt = keepcnt;
-                conn->keeptime = clock_systime_ticks();   /* Reset start time */
+
-                ret = OK;
+                /* Reset time */
+
+                if (conn->keepalive)
+                  {
+                    conn->keeptimer   = conn->keepidle;
+                    conn->keepretries = 0;
+                  }
               }
           }
         break;

net/tcp/tcp_timer.c

@@ -375,31 +375,19 @@ void tcp_timer(FAR struct net_driver_s *dev, FAR struct tcp_conn_s *conn,
 
           if (conn->keepalive)
             {
-              socktimeo_t timeo;
               uint32_t saveseq;
 
-              /* If this is the first probe, then the keepstart time is
-               * the time that the last ACK or data was received from the
-               * remote.
-               *
-               * On subsequent retries, keepstart is the time that the
-               * last probe was sent.
-               */
-
-              if (conn->keepretries > 0)
-                {
-                  timeo = (socktimeo_t)conn->keepintvl;
-                }
-              else
-                {
-                  timeo = (socktimeo_t)conn->keepidle;
-                }
-
               /* Yes... has the idle period elapsed with no data or ACK
                * received from the remote peer?
                */
 
-              if (net_timeo(conn->keeptime, timeo))
+              if (conn->keeptimer > hsec)
+                {
+                  /* Will not yet decrement to zero */
+
+                  conn->keeptimer -= hsec;
+                }
+              else
                 {
                   /* Yes.. Has the retry count expired? */
 
@@ -464,7 +452,7 @@ void tcp_timer(FAR struct net_driver_s *dev, FAR struct tcp_conn_s *conn,
 #endif
                       /* Update for the next probe */
 
-                      conn->keeptime = clock_systime_ticks();
+                      conn->keeptimer = conn->keepintvl;
                       conn->keepretries++;
                     }