Add clock type. Calculating RTT.

src/prrt/CMakeLists.txt

-add_library(PRRT ../defines.h socket.c block.c block.h packet.c packet.h receiver.c receiver.h processes/feedback_receiver.c processes/feedback_receiver.h processes/data_transmitter.c processes/data_transmitter.h coding_params.c coding_params.h vdmcode/block_code.c vdmcode/block_code.h coding_params.c coding_params.h stores/forward_packet_table.c stores/forward_packet_table.h processes/data_receiver.c processes/data_receiver.h)
\ No newline at end of file
+add_library(PRRT ../defines.h socket.c block.c block.h packet.c packet.h receiver.c receiver.h clock.c clock.h processes/feedback_receiver.c processes/feedback_receiver.h processes/data_transmitter.c processes/data_transmitter.h coding_params.c coding_params.h vdmcode/block_code.c vdmcode/block_code.h coding_params.c coding_params.h stores/forward_packet_table.c stores/forward_packet_table.h processes/data_receiver.c processes/data_receiver.h)
\ No newline at end of file

src/prrt/clock.c

+#include <sys/time.h>
+#include <stddef.h>
+#include "clock.h"
+
+uint32_t PrrtClock_get_current_time(void) {
+    struct timeval tv;
+    gettimeofday(&tv, NULL);
+    uint32_t time_in_micros = (uint32_t) (1000000 * tv.tv_sec + tv.tv_usec);
+    return time_in_micros;
+}

src/prrt/clock.h

+#ifndef PRRT_CLOCK_H
+#define PRRT_CLOCK_H
+
+#include <stdint.h>
+
+uint32_t PrrtClock_get_current_time(void);
+
+#endif //PRRT_CLOCK_H

src/prrt/packet.c

@@ -8,6 +8,7 @@
 #include <stdbool.h>
 #include <arpa/inet.h>
 #include "packet.h"
+#include "clock.h"
 
 void *encode_general_header(void *buf_ptr, const PrrtPacket *packet);
 
@@ -417,11 +418,7 @@ PrrtPacket *PrrtPacket_create_data_packet(uint8_t priority, const void *payloadP
     check_mem(dataPayload);
     packet->payload = dataPayload;
 
-    struct timeval tv;
-    gettimeofday(&tv, NULL);
-    unsigned long time_in_micros = (unsigned long) (1000000 * tv.tv_sec + tv.tv_usec);
-
-    dataPayload->timestamp = (uint32_t) time_in_micros;
+    dataPayload->timestamp = PrrtClock_get_current_time();
     dataPayload->group_round_trip_time = 95; // TODO: payload->rtt = CURRENT ESTIMATE
     dataPayload->packet_timeout = 110; // TODO: payload->packet_timeout = NOW + maximum delay
     dataPayload->decoding_timeout = 150; // TODO: payload->decoding_timeout
@@ -486,4 +483,9 @@ PrrtPacket *PrrtPacket_create_feedback_packet(uint8_t priority, uint8_t index, u
 
     error:
     return NULL;
+}
+
+uint32_t PrrtPacket_get_data_timestamp(PrrtPacket* packet) {
+    PrrtPacketDataPayload* payload = packet->payload;
+    return payload->timestamp;
 }
\ No newline at end of file

src/prrt/packet.h

@@ -81,4 +81,6 @@ int PrrtPacket_destroy(PrrtPacket *packet);
 #define PrrtPacket_copy_payload_to_buffer(dst, packet, header_size) memcpy(dst, packet->payload + header_size, packet->payload_len - header_size);
 #define PrrtPacket_copy_buffer_to_payload(packet, src, header_size) memcpy(packet->payload + header_size, src, packet->payload_len - header_size);
 
+uint32_t PrrtPacket_get_data_timestamp(PrrtPacket* packet);
+
 #endif //PRRT_FRAME_H

src/prrt/processes/data_receiver.c

 #include <netdb.h>
 #include <stdio.h>
 #include <arpa/inet.h>
+#include <src/prrt/clock.h>
 #include "../../defines.h"
 #include "../../util/dbg.h"
 #include "../../util/common.h"
@@ -61,7 +62,8 @@ bool send_feedback(const PrrtSocket *sock_ptr, struct sockaddr_in remote)
     hp = gethostbyname(remote_host);
     memcpy((void *) &targetaddr.sin_addr, hp->h_addr_list[0], (size_t) hp->h_length);
 
-    PrrtPacket *feedback_pkt_ptr = PrrtPacket_create_feedback_packet(0, 19, 4715, 7, 3, 50, 4, 6, 8, 9, 5, 1);
+    uint32_t forwardTripTime = PrrtClock_get_current_time() + sock_ptr->lastSentTimestamp - sock_ptr->lastReceivedTimestamp;
+    PrrtPacket *feedback_pkt_ptr = PrrtPacket_create_feedback_packet(0, 19, 4715, 3, forwardTripTime, 50, 4, 6, 8, 9, 5, 1);
     uint32_t length = PrrtPacket_size(feedback_pkt_ptr);
     void *buf = calloc(1, length);
     check_mem(buf);
@@ -92,12 +94,16 @@ void *receive_data_loop(void *ptr)
     while(1) {
         memset(buffer, 0, MAX_PAYLOAD_LENGTH);
         n = recvfrom(sock_ptr->dataSocketFd, buffer, MAX_PAYLOAD_LENGTH, 0, (struct sockaddr *) &remote, &addrlen);
-        check(send_feedback(sock_ptr, remote), "Sending feedback failed.");
+        sock_ptr->lastReceivedTimestamp = PrrtClock_get_current_time();
 
         PrrtPacket *packet = (PrrtPacket *) calloc(1, sizeof(PrrtPacket));
         check_mem(packet);
         check(PrrtPacket_decode(buffer, (uint16_t) n, packet), "Decode failed.");
 
+        sock_ptr->lastSentTimestamp = PrrtPacket_get_data_timestamp(packet);
+
+        check(send_feedback(sock_ptr, remote), "Sending feedback failed.");
+
         uint8_t packetType = PrrtPacket_type(packet);
         if(packetType == PACKET_TYPE_DATA) {
             // TODO: packet.timestamp + packet.timeout < now: break

src/prrt/processes/data_transmitter.c

@@ -3,9 +3,10 @@
 #include <unistd.h>
 #include <string.h>
 #include "../../defines.h"
-#include "../socket.h"
 #include "../block.h"
+#include "../clock.h"
 #include "../receiver.h"
+#include "../socket.h"
 #include "../../util/dbg.h"
 #include "../../util/common.h"
 #include "data_transmitter.h"
@@ -33,6 +34,7 @@ bool send_packet(PrrtSocket *sock_ptr, PrrtPacket *packet) {
         check(hp != NULL, "Could not resolve host '%s'.", recv->host_name)
         memcpy((void *) &targetaddr.sin_addr, hp->h_addr_list[0], (size_t) hp->h_length);
 
+        // TODO: to minimize impact of processing delay to the RTT measurement, the timestamp should be taken and saved here
         check(sendto(sock_ptr->dataSocketFd, buf, length, 0, (struct sockaddr *) &targetaddr, sizeof(targetaddr)) == length, "Sendto failed.");
         usleep(1);
     }
@@ -73,6 +75,10 @@ void * send_data_loop(void *ptr) {
         }
 
         PrrtPacket *packet = List_shift(sock_ptr->outQueue);
+
+        PrrtPacketDataPayload* dataPayload = packet->payload;
+        dataPayload->timestamp = PrrtClock_get_current_time();
+
         packet->seqno = sock_ptr->sequenceNumberSource++;
         packet->index = (uint8_t) (packet->seqno - block->baseSequenceNumber);
 

src/prrt/processes/feedback_receiver.c

@@ -3,6 +3,7 @@
 #include "../../defines.h"
 #include "../../util/common.h"
 #include "../../util/dbg.h"
+#include "../clock.h"
 #include "../packet.h"
 #include "../socket.h"
 #include "feedback_receiver.h"

src/prrt/socket.c

@@ -15,6 +15,7 @@
 #include "socket.h"
 #include "block.h"
 #include "receiver.h"
+#include "clock.h"
 
 PrrtSocket* PrrtSocket_create(const uint16_t port, const uint8_t is_sender) {
     PrrtSocket *sock_ptr = (PrrtSocket*) calloc(1, sizeof(PrrtSocket));
@@ -273,6 +274,8 @@ PrrtPacket *PrrtSocket_recv_feedback(const PrrtSocket *sock_ptr, const size_t le
     n = recvfrom(sock_ptr->feedbackSocketFd, bufin, length, 0, (struct sockaddr *) &remote, &addrlen);
     check(n >= 0, "Receiving feedback failed.");
 
+    uint32_t receive_time = PrrtClock_get_current_time();
+
     //uint16_t remote_port = ntohs(remote.sin_port);
     //char *remote_host = inet_ntoa(remote.sin_addr);
     //debug("Received feedback %s:%d", remote_host, remote_port);

src/prrt/socket.h

@@ -40,6 +40,9 @@ typedef struct prrtSocket {
     uint16_t sequenceNumberRedundancy;
     uint16_t sequenceNumberFeedback;
     uint8_t is_sender;
+
+    uint32_t lastSentTimestamp;
+    uint32_t lastReceivedTimestamp;
 } PrrtSocket;