TCB.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 "List.h"
#include "TCP_Header.h"
 
//Function prototype
static void free_queue(PTCP_QUEUE queue);
 
 
UINT32 calculate_initial_seq_num(double time)
{
    return max(1,(UINT32)(time/4.0));
}
 
char* state_to_str(TCP_CONNECTION_STATE state)
{
    switch (state)
    {
    case TCPCONNECTION_CLOSED:
        return "Closed";
    case TCPCONNECTION_LISTEN:
        return "Listen";
    case TCPCONNECTION_CLOSE_WAIT:
        return "Close-Wait";
    case TCPCONNECTION_CLOSING:
        return "Closing";
    case TCPCONNECTION_ESTABLISHED:
        return "Established";
    case TCPCONNECTION_FIN_WAIT_1:
        return "Fin-Wait-1";
    case TCPCONNECTION_FIN_WAIT_2:
        return "Fin-wait-2";
    case TCPCONNECTION_LAST_ACK:
        return "Last-Ack";
    case TCPCONNECTION_SYN_RECEIVED:
        return "Syn-received";
    case TCPCONNECTION_TIME_WAIT:
        return "Time-wait";
    case TCPCONNECTION_SYN_SENT:
        return "Syn-sent";
    default:
        return "Unknown";
    }
}
 
static void set_tcp_variant(PNETSIM_SOCKET s, PTCP_DEV_VAR t)
{
    s->tcb->variant = t->tcpVariant;
    switch (s->tcb->variant)
    {
    case TCPVariant_OLDTAHOE:
    case TCPVariant_TAHOE:
    case TCPVariant_RENO:
    case TCPVariant_NEWRENO:
    case TCPVariant_BIC:
    case TCPVariant_CUBIC:
        congestion_setcallback(s);
        break;
    default:
        fnNetSimError("Unknown tcp variant %d in %s\n",
                      t->tcpVariant,
                      __FUNCTION__);
        break;
    }
}
 
static void setSackPermitted(PNETSIM_SOCKET s, PTCP_DEV_VAR t)
{
    s->tcb->isSackPermitted = t->isSackPermitted;
}
 
static void set_timestamp_option(PNETSIM_SOCKET s, PTCP_DEV_VAR t)
{
    s->tcb->isTSopt = t->isTimestampOpt;
}
 
void create_TCB(PNETSIM_SOCKET s)
{
    PTCP_DEV_VAR tcp = GET_TCP_DEV_VAR(s->localDeviceId);
    PTCB tcb = (PTCB)calloc(1, sizeof* tcb);
    s->tcb = tcb;
 
    set_tcp_variant(s, tcp);
 
    set_ack_type(s, tcp);
 
    setSackPermitted(s, tcp);
 
    set_window_scaling_option(s, tcp);
 
    set_timestamp_option(s, tcp);
    
    TCP_RTO(tcb) = calculate_RTO(0,
                                 &TCP_SRTT(tcb),
                                 &TCP_RTTVAR(tcb));
 
    print_tcp_log("New RTO = %0.2lf", TCP_RTO(tcb));
 
    tcb->timeWaitTimer = tcp->timeWaitTimer;
 
    tcb->ISS = calculate_initial_seq_num(pstruEventDetails->dEventTime);
    tcb->SND.WND = tcb->get_WND(s);
    tcb->RCV.WND = tcb->get_RCVWND(s);
    
    //Start with closed state
    tcb->tcp_state = TCPCONNECTION_CLOSED;
    tcb->tcp_prev_state = TCPCONNECTION_CLOSED;
 
    //Set initial RMSS and SMSS size
    s->tcb->init_congestionalgo(s);
}
 
void free_tcb(PTCB tcb)
{
    free_queue(&tcb->retransmissionQueue);
    free(tcb);
}
 
void delete_tcb(PNETSIM_SOCKET s)
{
    free_tcb(s->tcb);
    s->tcb = NULL;
}
 
void tcp_change_state(PNETSIM_SOCKET s, TCP_CONNECTION_STATE state)
{
    PTCB tcb = s->tcb;
    if (tcb->tcp_state != state)
    {
        tcb->tcp_prev_state = tcb->tcp_state;
        tcb->tcp_state = state;
        print_tcp_log("TCP state is changed to \"%s\" from \"%s\".",
                      state_to_str(tcb->tcp_state),
                      state_to_str(tcb->tcp_prev_state));
    }
}
 
static void free_queue(PTCP_QUEUE queue)
{
    PQueueInfo info = queue->queue;
    while (info)
    {
        NetSim_PACKET* p = info->packet;
        PQueueInfo i = info;
        info = info->next;
        free(i);
        fn_NetSim_Packet_FreePacket(p);
    }
}
 
void add_packet_to_queue(PTCP_QUEUE queue, NetSim_PACKET* packet, double time)
{
    PQueueInfo info = queue->queue;
    
    PQueueInfo ninfo = (PQueueInfo)calloc(1, sizeof* ninfo);
    ninfo->packet = packet;
    ninfo->time = time;
 
    PTCP_SEGMENT_HDR hdr = TCP_GET_SEGMENT_HDR(packet);
 
    if (info)
    {
        PQueueInfo pinfo = NULL;
        while (info)
        {
            NetSim_PACKET* p = info->packet;
            PTCP_SEGMENT_HDR h = TCP_GET_SEGMENT_HDR(p);
 
            if (h->SeqNum < hdr->SeqNum)
            {
                pinfo = info;
                info = info->next;
            }
            else
            {
                if (pinfo)
                {
                    pinfo->next = ninfo;
                    ninfo->next = info;
                }
                else
                {
                    ninfo->next = info;
                    queue->queue = ninfo;
                }
                break;
            }
        }
        if (!info)
        {
            pinfo->next = ninfo;
        }
    }
    else
    {
        queue->queue = ninfo;
    }
    queue->size += (UINT)packet->pstruTransportData->dPacketSize;
}
 
bool isSegmentInQueue(PTCP_QUEUE queue, NetSim_PACKET* packet)
{
    PTCP_SEGMENT_HDR hdr = TCP_GET_SEGMENT_HDR(packet);
    PQueueInfo info = queue->queue;
    while (info)
    {
        NetSim_PACKET* p = info->packet;
        PTCP_SEGMENT_HDR h = TCP_GET_SEGMENT_HDR(p);
        if (hdr->SeqNum == h->SeqNum)
            return true;
        info = info->next;
    }
    return false;
}
 
NetSim_PACKET* get_segment_from_queue(PTCP_QUEUE queue, UINT32 seqNo)
{
    PQueueInfo info = queue->queue;
    PQueueInfo pr=NULL;
    while (info)
    {
        NetSim_PACKET* p = info->packet;
        PTCP_SEGMENT_HDR hdr = TCP_GET_SEGMENT_HDR(p);
        if (hdr->SeqNum == seqNo)
        {
            queue->size -= (UINT)p->pstruTransportData->dPacketSize;
            if (pr)
            {
                pr->next = info->next;
                free(info);
            }
            else
            {
                queue->queue = info->next;
                free(info);
            }
            return p;
        }
        pr = info;
        info = info->next;
    }
    return NULL;
}
 
NetSim_PACKET* get_earliest_segment_from_queue(PTCP_QUEUE queue)
{
    PQueueInfo info = queue->queue;
    if (info)
    {
        NetSim_PACKET* p = info->packet;
        queue->size -= (UINT)p->pstruTransportData->dPacketSize;
 
        queue->queue = info->next;
        free(info);
        return p;
    }
    return NULL;
}
 
NetSim_PACKET* get_earliest_copy_segment_from_queue(PTCP_QUEUE queue)
{
    PQueueInfo info = queue->queue;
    if (info)
    {
        NetSim_PACKET* p = info->packet;
        
        return fn_NetSim_Packet_CopyPacket(p);
    }
    return NULL;
}
 
NetSim_PACKET* get_copy_segment_from_queue(PTCP_QUEUE queue, UINT32 seqNo, bool* isSacked)
{
    PQueueInfo info = queue->queue;
    PQueueInfo pr = NULL;
    while (info)
    {
        NetSim_PACKET* p = info->packet;
        PTCP_SEGMENT_HDR hdr = TCP_GET_SEGMENT_HDR(p);
        if (hdr->SeqNum == seqNo)
        {
            NetSim_PACKET* pret = fn_NetSim_Packet_CopyPacket(p);
            pret->pstruNextPacket = NULL;
            *isSacked = info->isSacked;
            return pret;
        }
        pr = info;
        info = info->next;
    }
    return NULL;
}
 
 
UINT32 get_seg_len(NetSim_PACKET* p)
{
    PTCP_SEGMENT_HDR hdr = TCP_GET_SEGMENT_HDR(p);
    if (hdr->Syn)
        return 1;
    else
        return (UINT32)(p->pstruTransportData->dPayload);
}
 
void delete_segment_from_queue(PTCP_QUEUE queue, UINT32 ackNo)
{
    PQueueInfo info = queue->queue;
    PQueueInfo pr = NULL;
    while (info)
    {
        NetSim_PACKET* p = info->packet;
        PTCP_SEGMENT_HDR hdr = TCP_GET_SEGMENT_HDR(p);
        if (hdr->SeqNum + get_seg_len(p) <= ackNo)
        {
            //Delete
            queue->size -= (UINT)p->pstruTransportData->dPacketSize;
            if (pr)
            {
                pr->next = info->next;
                free(info);
                info = pr->next;
            }
            else
            {
                queue->queue = info->next;
                free(info);
                info = queue->queue;
            }
            fn_NetSim_Packet_FreePacket(p);
            continue;
        }
        pr = info;
        info = info->next;
    }
}
 
bool isAnySegmentInQueue(PTCP_QUEUE queue)
{
    return queue->size > 0;
}
 
void delete_all_segment_from_queue(PTCP_QUEUE queue)
{
    free_queue(queue);
}
 
void update_seq_num_on_receiving(PNETSIM_SOCKET s,
                                 NetSim_PACKET* p)
{
    PTCP_SEGMENT_HDR hdr = TCP_GET_SEGMENT_HDR(p);
    PTCB t = s->tcb;
    if (t)
    {
        t->SEG.ACK = hdr->AckNum;
        t->SEG.LEN = get_seg_len(p);
        t->SEG.SEQ = hdr->SeqNum;
        t->SEG.WND = hdr->Window;
    }
}
 
double get_RTT(PTCB tcb, UINT ackNo)
{
    PQueueInfo info = tcb->retransmissionQueue.queue;
    while (info)
    {
        NetSim_PACKET* p = info->packet;
        PTCP_SEGMENT_HDR hdr = TCP_GET_SEGMENT_HDR(p);
        if (hdr->SeqNum + get_seg_len(p) == ackNo)
        {
            return pstruEventDetails->dEventTime - info->time;
        }
        info = info->next;
    }
    return 0;
}
 
NetSim_PACKET* check_for_other_segment_to_send_from_queue(PNETSIM_SOCKET s)
{
    PTCP_QUEUE queue = &s->tcb->outOfOrderSegment;
    PQueueInfo info = queue->queue;
    NetSim_PACKET* pr = NULL;
    if (info)
    {
        pr = info->packet;
        PTCP_SEGMENT_HDR h = TCP_GET_SEGMENT_HDR(pr);
        if (h->SeqNum < s->tcb->RCV.NXT)
        {
            //Delete
            queue->size -= (UINT)pr->pstruTransportData->dPacketSize;
            queue->queue = info->next;
            free(info);
        }
        else
            pr = NULL;
    }
    return pr;
}
 
void check_segment_in_queue(PNETSIM_SOCKET s)
{
    PTCP_QUEUE queue = &s->tcb->outOfOrderSegment;
    PQueueInfo info = queue->queue;
    while (info)
    {
        NetSim_PACKET* pr = NULL;
        pr = info->packet;
        PTCP_SEGMENT_HDR h = TCP_GET_SEGMENT_HDR(pr);
        if (h->SeqNum == s->tcb->RCV.NXT)
        {
            s->tcb->RCV.NXT += get_seg_len(pr);
        }
        info = info->next;
    }
}
 
void set_timestamp_value(PNETSIM_SOCKET s,
                         PTCP_SEGMENT_HDR hdr,
                         PTSopt opt)
{
    if (hdr->Syn)
    {
        if (opt && s->tcb->isTSopt)
            s->tcb->isTSopt = true;
        else
            s->tcb->isTSopt = false;
    }
 
    if (opt && s->tcb->isTSopt)
    {
        s->tcb->TSVal = opt->TSval;
    }
 
}