added rtt and rtt deviation calculation for the tcp layer

src/arp.c

@@ -223,8 +223,10 @@ static void arp_translation_table_seconds_passed(arp_translation_table_t *table,
     }
 }
 
-void arp_seconds_passed(arp_state_t *state, size_t seconds)
+void arp_ms_passed(arp_state_t *state, size_t ms)
 {
+    size_t seconds = ms / 1000;
+    
     state->time += seconds;
 
     // Scan through all of the timed-out entries

src/arp.h

@@ -124,5 +124,5 @@ void arp_resolve_mac(arp_state_t *state,
                      void *userp, 
                      void (*callback)(void*, arp_resolution_status_t, mac_address_t));
 
-void arp_seconds_passed(arp_state_t *state, size_t seconds);
+void arp_ms_passed(arp_state_t *state, size_t ms);
 void arp_change_output_buffer(arp_state_t *state, void *ptr, size_t max);

src/defs.h

@@ -22,5 +22,6 @@ typedef struct {
 
 #define MIN(X, Y) ((X) < (Y) ? (X) : (Y))
 #define MAX(X, Y) ((X) > (Y) ? (X) : (Y))
+#define ABS(X) ((X) < 0 ? -(X) : (X))
 
 #endif /* MICROTCP_DEFS_H */

src/ip.c

@@ -29,7 +29,6 @@ static uint16_t calculate_checksum_ip(const void *src, size_t len)
     return cpu_to_net_u16(~sum);
 }
 
-
 static ip_plugged_protocol_t *
 find_protocol_with_id(ip_state_t *ip_state, uint8_t protocol)
 {
@@ -125,10 +124,10 @@ void ip_change_output_buffer(ip_state_t *state, void *ptr, size_t max)
     icmp_change_output_buffer(&state->icmp_state, (ip_packet_t*) ptr + 1, max - sizeof(ip_packet_t));
 }
 
-void ip_seconds_passed(ip_state_t *state, size_t seconds)
+void ip_ms_passed(ip_state_t *state, size_t ms)
 {
     (void) state;
-    (void) seconds;
+    (void) ms;
 }
 
 int ip_send(ip_state_t *state, ip_protocol_t protocol, 

src/ip.h

@@ -54,7 +54,7 @@ typedef struct {
     ip_plugged_protocol_t plugged_protocols[IP_PLUGGED_PROTOCOLS_MAX];
 } ip_state_t;
 
-void ip_seconds_passed(ip_state_t *state, size_t seconds);
+void ip_ms_passed(ip_state_t *state, size_t ms);
 void ip_change_output_buffer(ip_state_t *state, void *ptr, size_t max);
 void ip_init(ip_state_t *state, ip_address_t ip, void *send_data, void (*send)(void*, ip_address_t, size_t));
 void ip_free(ip_state_t *state);

src/microtcp.c

@@ -105,7 +105,7 @@ struct microtcp_socket_t {
 
 struct microtcp_t {
 
-    time_t last_update_time;
+    uint64_t last_update_time_ms;
 
 #ifdef MICROTCP_BACKGROUND_THREAD
     bool thread_should_stop;
@@ -396,6 +396,13 @@ void microtcp_process_packet(microtcp_t *mtcp, const void *packet, size_t len)
     UNLOCK_WHEN_THREADED(mtcp);
 }
 
+static uint64_t get_time_in_ms(void)
+{
+    struct timespec t;
+    clock_gettime(CLOCK_MONOTONIC, &t);
+    return t.tv_sec * 1000 + t.tv_nsec / 1000000;
+}
+
 void microtcp_step(microtcp_t *mtcp)
 {
     char packet[1024]; // This buffer is the bottleneck for the 
@@ -408,18 +415,20 @@ void microtcp_step(microtcp_t *mtcp)
     if (size < 0)
         return;
 
+    uint64_t current_time_ms = get_time_in_ms();
+    fprintf(stderr, "current_time_ms=%lld\n", current_time_ms);
+
     LOCK_WHEN_THREADED(mtcp);
     {
         process_packet(mtcp, packet, size);
         
-        time_t current_time = time(NULL);
-        int secs = (float) (current_time - mtcp->last_update_time);
+        uint64_t ms = (current_time_ms - mtcp->last_update_time_ms);
         
-        if (secs > 0) {
-            ip_seconds_passed(&mtcp->ip_state, secs);
-            arp_seconds_passed(&mtcp->arp_state, secs);
-            tcp_seconds_passed(&mtcp->tcp_state, secs);
-            mtcp->last_update_time = current_time;
+        if (ms > 0) {
+            ip_ms_passed(&mtcp->ip_state, ms);
+            arp_ms_passed(&mtcp->arp_state, ms);
+            tcp_ms_passed(&mtcp->tcp_state, ms);
+            mtcp->last_update_time_ms = current_time_ms;
         }
     }
     UNLOCK_WHEN_THREADED(mtcp);
@@ -458,7 +467,7 @@ microtcp_t *microtcp_create_using_callbacks(const char *ip, const char *mac,
     mtcp->ip = parsed_ip;
     mtcp->mac = parsed_mac;
     mtcp->callbacks = callbacks;
-    mtcp->last_update_time = time(NULL);
+    mtcp->last_update_time_ms = get_time_in_ms();
 
     mtcp->used_buffer = NULL;
     mtcp->wait_buffer_list = NULL;

src/tcp.c

@@ -42,9 +42,9 @@ void tcp_free(tcp_state_t *state)
     tcp_timerset_free(&state->timers);
 }
 
-void tcp_seconds_passed(tcp_state_t *state, size_t seconds)
+void tcp_ms_passed(tcp_state_t *state, size_t ms)
 {
-    tcp_timerset_step(&state->timers, seconds);
+    tcp_timerset_step(&state->timers, ms);
 }
 
 static tcp_connection_t*
@@ -74,6 +74,13 @@ connection_create(tcp_listener_t *listener,
 
         connection->state = TCP_STATE_CLOSED;
 
+        connection->rtt = 0;
+        connection->dev_rtt = 0;
+
+        connection->calculating_rtt = false;
+        connection->rtt_calc_seq = 0;
+        connection->rtt_calc_time = 0;
+
         connection->peer_port = peer_port;
         connection->peer_ip   = peer_ip;
 
@@ -110,7 +117,7 @@ find_listener_with_port(tcp_state_t *state, uint16_t port)
     return NULL;
 }
 
-static uint32_t choose_sequence_no()
+static uint32_t choose_sequence_no(void)
 {
     return 0;
 }
@@ -222,6 +229,11 @@ static void emit_segment(tcp_connection_t *connection, uint8_t flags, size_t pay
         }
     }
 
+    if (!connection->calculating_rtt) {
+        connection->calculating_rtt = true;
+        connection->rtt_calc_seq = connection->snd_nxt; // -1?
+        connection->rtt_calc_time = connection->listener->state->timers.current_time_ms;
+    }
 }
 
 static void handle_received_data(tcp_connection_t *connection, 
@@ -331,10 +343,30 @@ static bool ack_until(tcp_connection_t *connection, uint32_t ack_no)
     }
     
     size_t newly_acked_bytes = ack_no - connection->snd_una;
-    memmove(connection->out_buffer, connection->out_buffer + newly_acked_bytes, connection->snd_wnd - newly_acked_bytes);
-    connection->snd_wnd -= newly_acked_bytes;
+
+    if (ack_no > 1) { // Only remove data from the output buffer when
+                      // the acked data wasn't a ghost byte
+        memmove(connection->out_buffer, connection->out_buffer + newly_acked_bytes, connection->snd_wnd - newly_acked_bytes);
+        connection->snd_wnd -= newly_acked_bytes;
+    }
     connection->snd_una = ack_no;
 
+    TCP_DEBUG_LOG("calculating_rtt=%s, ack_no=%d, calc_seq=%d", connection->calculating_rtt ? "true" : "false", ack_no, connection->rtt_calc_seq);
+    if (connection->calculating_rtt) {
+        if (ack_no >= connection->rtt_calc_seq) {
+
+            uint64_t rtt = connection->listener->state->timers.current_time_ms - connection->rtt_calc_time;
+            TCP_DEBUG_LOG("Estimated RTT=%lld", rtt);
+
+            float w1 = 0.9;
+            float w2 = 0.125;
+            connection->rtt = w1 * rtt + (1-w1) * connection->rtt;
+            connection->dev_rtt = w2 * ABS((int) rtt - (int) connection->rtt) + (1-w2) * connection->dev_rtt;
+
+            connection->calculating_rtt = false;
+        }
+    }
+
     return true;
 }
 
@@ -519,6 +551,9 @@ void tcp_process_segment(tcp_state_t *state, ip_address_t sender,
         TCP_DEBUG_LOG("Connection request handled");
 
     } else {
+
+        TCP_DEBUG_LOG("RTT=%lld, DevRTT=%lld", connection->rtt, connection->dev_rtt);
+
         // Something sent to an already instanciated
         // connection. Since there is an instance, it
         // means that at least the first SYN was received
@@ -560,7 +595,8 @@ void tcp_process_segment(tcp_state_t *state, ip_address_t sender,
                               "the peer will retransmit it");
 
             // The connection is now established.
-            connection->snd_una = net_to_cpu_u32(segment->ack_no);
+            uint32_t ack_no = net_to_cpu_u32(segment->ack_no);
+            ack_until(connection, ack_no);
             connection->state = TCP_STATE_ESTAB;
 
             move_from_non_established_list_to_non_accepted_queue(connection);
@@ -747,8 +783,6 @@ tcp_connection_t *tcp_listener_accept(tcp_listener_t *listener, void *callback_d
                                       void (*callback_ready_to_recv)(void*), 
                                       void (*callback_ready_to_send)(void*))
 {
-    (void) listener;
-
     if (!listener->non_accepted_queue_head)
         // Nothing to accept
         return NULL;

src/tcp.h

@@ -6,7 +6,7 @@
 #include "tcp_timer.h"
 #endif
 
-#define TCP_TIMEOUT_TIME_WAIT 240
+#define TCP_TIMEOUT_TIME_WAIT 240000
 
 #define TCP_MAX_TIMEOUTS 1024
 #define TCP_MAX_LISTENERS 32
@@ -88,6 +88,13 @@ struct tcp_connection_t {
     ip_address_t peer_ip; // Network byte order
     uint16_t     peer_port; // CPU byte order
 
+    uint64_t rtt;
+    uint64_t dev_rtt;
+
+    bool calculating_rtt;
+    uint32_t rtt_calc_seq;
+    uint64_t rtt_calc_time;
+
     // Send Sequence Space
     //
     //               1         2          3          4      
@@ -166,7 +173,7 @@ struct tcp_state_t {
 
 void              tcp_init(tcp_state_t *tcp_state, ip_address_t ip, tcp_callbacks_t callbacks);
 void              tcp_free(tcp_state_t *tcp_state);
-void              tcp_seconds_passed(tcp_state_t *state, size_t seconds);
+void              tcp_ms_passed(tcp_state_t *state, size_t ms);
 void              tcp_process_segment(tcp_state_t *state, ip_address_t sender, tcp_segment_t *segment, size_t len);
 tcp_listener_t   *tcp_listener_create(tcp_state_t *state, uint16_t port, bool reuse, void *data, void (*callback)(void*));
 void              tcp_listener_destroy(tcp_listener_t *listener);

src/tcp_timer.c

@@ -41,7 +41,7 @@ void tcp_timer_disable(tcp_timer_t *timer)
     set->free_list = timer;
 }
 
-tcp_timer_t *tcp_timer_create(tcp_timerset_t *set, size_t seconds, 
+tcp_timer_t *tcp_timer_create(tcp_timerset_t *set, size_t ms, 
                               void (*callback)(void*), void *data)
 {
     assert(callback);
@@ -58,7 +58,7 @@ tcp_timer_t *tcp_timer_create(tcp_timerset_t *set, size_t seconds,
     //       first item of the free list.
 
     timer->set = set;
-    timer->deadline = set->current_time + seconds;
+    timer->deadline = set->current_time_ms + ms;
     timer->data = data;
     timer->callback = callback;
     
@@ -107,11 +107,11 @@ tcp_timer_t *tcp_timer_create(tcp_timerset_t *set, size_t seconds,
     return timer;
 }
 
-void tcp_timerset_step(tcp_timerset_t *set, size_t seconds)
+void tcp_timerset_step(tcp_timerset_t *set, size_t ms)
 {
-    set->current_time += seconds;
+    set->current_time_ms += ms;
 
-    if (set->used_list == NULL || set->used_list->deadline > set->current_time)
+    if (set->used_list == NULL || set->used_list->deadline > set->current_time_ms)
         // No timeouts triggered
         return;
 
@@ -122,7 +122,7 @@ void tcp_timerset_step(tcp_timerset_t *set, size_t seconds)
     tcp_timer_t *timeout = set->used_list;
     while (timeout) {
 
-        if (timeout->deadline > set->current_time)
+        if (timeout->deadline > set->current_time_ms)
             // This timeout didn't trigger, so the last 
             // timed out timeout was the previous one.
             break;

src/tcp_timer.h

@@ -17,15 +17,15 @@ struct tcp_timer_t {
 };
 
 struct tcp_timerset_t {
-    uint64_t current_time;
+    uint64_t current_time_ms;
     tcp_timer_t *used_list;
     tcp_timer_t *free_list;
     tcp_timer_t pool[TCP_MAX_TIMERS];
 };
 
-void tcp_timerset_step(tcp_timerset_t *set, size_t seconds);
+void tcp_timerset_step(tcp_timerset_t *set, size_t ms);
 void tcp_timerset_init(tcp_timerset_t *set);
 void tcp_timerset_free(tcp_timerset_t *set);
 void tcp_timer_disable(tcp_timer_t *timer);
-tcp_timer_t *tcp_timer_create(tcp_timerset_t *set, size_t seconds, 
+tcp_timer_t *tcp_timer_create(tcp_timerset_t *set, size_t ms, 
                               void (*callback)(void*), void *data);