TCP_Outgoing.c

/************************************************************************************
* Copyright (C) 2023                                                               *
* TETCOS, Bangalore. India                                                         *
*                                                                                  *
* Tetcos owns the intellectual property rights in the Product and its content.     *
* The copying, redistribution, reselling or publication of any or all of the       *
* Product or its content without express prior written consent of Tetcos is        *
* prohibited. Ownership and / or any other right relating to the software and all  *
* intellectual property rights therein shall remain at all times with Tetcos.      *
*                                                                                  *
* Author:    Shashi Kant Suman                                                     *
*                                                                                  *
* ---------------------------------------------------------------------------------*/
#include "main.h"
#include "TCP.h"
#include "TCP_Header.h"
 
void send_segment(PNETSIM_SOCKET s)
{
    PTCB t = s->tcb;
    UINT32 seq = t->SND.NXT;
    if (!s->sId)
        fnNetSimError("SOCKETINTERFACE is NULL for TCP connection %s:%d %s:%d in function %s\n",
                      s->localAddr->ip->str_ip,
                      s->localAddr->port,
                      s->remoteAddr->ip->str_ip,
                      s->remoteAddr->port,
                      __FUNCTION__);
    NetSim_PACKET* p = fn_NetSim_Socket_GetPacketFromInterface(s->sId, 0);
    if (!p)
        s->waitFromApp = true; //Enable flag to signal application waiting.
 
    t->SND.WND = window_scale_get_cwnd(s);
    assert(t->SND.WND >= t->get_MSS(s));
    while (p)
    {
        UINT32 l = (UINT32)p->pstruAppData->dPacketSize;
        if (seq + l <= t->SND.WND + t->SND.UNA)
        {
            NetSim_PACKET* pt = fn_NetSim_Socket_GetPacketFromInterface(s->sId, 1);
            if (pt->pstruAppData->nAppEndFlag)
                s->isAPPClose = true; //Enable flag to signal application closing
 
            add_tcp_hdr(pt, s);
            t->SND.NXT += l;
            seq += l;
 
            s->tcpMetrics->segmentSent++;
 
            send_to_network(pt, s);
            add_timeout_event(s, pt);
            write_congestion_plot(s, pt);
        }
        else
            break; //No more segment allowed to send
 
        p = fn_NetSim_Socket_GetPacketFromInterface(s->sId, 0);
    }
 
    if (s->isAPPClose)
        tcp_close(s);
}
 
void resend_segment(PNETSIM_SOCKET s, NetSim_PACKET* expired)
{
    PTCP_SEGMENT_HDR hdr = TCP_GET_SEGMENT_HDR(expired);
    PTCP_QUEUE q = &s->tcb->retransmissionQueue;
 
    NetSim_PACKET* p = get_segment_from_queue(q, hdr->SeqNum);
    
    if (p)
    {   
        s->tcpMetrics->segmentRetransmitted++;
        send_to_network(p, s);
        add_timeout_event(s, p);
    }
}
 
void resend_segment_without_timeout(PNETSIM_SOCKET s, UINT seq)
{
    bool isSacked = false;
    PTCP_QUEUE q = &s->tcb->retransmissionQueue;
 
    NetSim_PACKET* p = get_copy_segment_from_queue(q, seq, &isSacked);
 
    if (s->tcb->isSackPermitted &&
        isSacked)
    {
        //Don't retransmit
        fn_NetSim_Packet_FreePacket(p);
        p = NULL;
    }
 
    if (p)
    {
        set_highRxt(s, seq);
        set_rescueRxt(s, seq);
        s->tcpMetrics->segmentRetransmitted++;
        send_to_network(p, s);
    }
}