/**
* This function should be called by the application when it has
* processed the data. The purpose is to advertise a larger window
* when the data has been processed.
*
* @param pcb the tcp_pcb for which data is read
* @param len the amount of bytes that have been read by the application
*/
void
tcp_recved(struct tcp_pcb *pcb, u16_t len)
{
int wnd_inflation;
LWIP_ASSERT("tcp_recved: len would wrap rcv_wnd\n",
len <= 0xffff - pcb->rcv_wnd );
pcb->rcv_wnd += len;
if (pcb->rcv_wnd > TCP_WND) {
pcb->rcv_wnd = TCP_WND;
}
wnd_inflation = tcp_update_rcv_ann_wnd(pcb);
/* If the change in the right edge of window is significant (default
* watermark is TCP_WND/4), then send an explicit update now.
* Otherwise wait for a packet to be sent in the normal course of
* events (or more window to be available later) */
if (wnd_inflation >= TCP_WND_UPDATE_THRESHOLD) {
tcp_ack_now(pcb);
tcp_output(pcb);
}
LWIP_DEBUGF(TCP_DEBUG, ("tcp_recved: recveived %"U16_F" bytes, wnd %"U16_F" (%"U16_F").\n",
len, pcb->rcv_wnd, TCP_WND - pcb->rcv_wnd));
}
/*-----------------------------------------------------------------------------------*/
void
tcp_recved(struct tcp_pcb *pcb, u16_t len)
{
u16_t new_rcv_wnd;
/* prevent overflow */
new_rcv_wnd = pcb->rcv_wnd + len;
if(pcb->rcv_wnd <= new_rcv_wnd){
pcb->rcv_wnd = new_rcv_wnd;
}else{
pcb->rcv_wnd = TCP_WND;
}
/* window may not exceed TCP_WND */
if(pcb->rcv_wnd > TCP_WND) {
pcb->rcv_wnd = TCP_WND;
}
#if 0
if(!(pcb->flags & TF_ACK_DELAY) ||
!(pcb->flags & TF_ACK_NOW)) {
tcp_ack(pcb);
}
#endif
if ((pcb->rcv_nxt + pcb->rcv_wnd) - pcb->rcv_adv >= 2 * pcb->mss) {
tcp_ack_now(pcb);
}
DEBUGF(TCP_DEBUG, ("tcp_recved: recveived %d bytes, wnd %u (%u).\n",
len, pcb->rcv_wnd, TCP_WND - pcb->rcv_wnd));
}
/**
* Called by tcp_input() when a segment arrives for a connection in
* TIME_WAIT.
*
* @param pcb the tcp_pcb for which a segment arrived
*
* @note the segment which arrived is saved in global variables, therefore only the pcb
* involved is passed as a parameter to this function
*/
static err_t
tcp_timewait_input(struct tcp_pcb *pcb)
{
if (TCP_SEQ_GT(seqno + tcplen, pcb->rcv_nxt)) {
pcb->rcv_nxt = seqno + tcplen;
}
if (tcplen > 0) {
tcp_ack_now(pcb);
}
return tcp_output(pcb);
}
/**
* This function should be called by the application when it has
* processed the data. The purpose is to advertise a larger window
* when the data has been processed.
*
* @param pcb the tcp_pcb for which data is read
* @param len the amount of bytes that have been read by the application
*/
void
tcp_recved(struct tcp_pcb *pcb, u16_t len)
{
if ((u32_t)pcb->rcv_wnd + len > TCP_WND) {
pcb->rcv_wnd = TCP_WND;
pcb->rcv_ann_wnd = TCP_WND;
} else {
pcb->rcv_wnd += len;
if (pcb->rcv_wnd >= pcb->mss) {
pcb->rcv_ann_wnd = pcb->rcv_wnd;
}
}
if (!(pcb->flags & TF_ACK_DELAY) &&
!(pcb->flags & TF_ACK_NOW)) {
/*
* We send an ACK here (if one is not already pending, hence
* the above tests) as tcp_recved() implies that the application
* has processed some data, and so we can open the receiver's
* window to allow more to be transmitted. This could result in
* two ACKs being sent for each received packet in some limited cases
* (where the application is only receiving data, and is slow to
* process it) but it is necessary to guarantee that the sender can
* continue to transmit.
*/
tcp_ack(pcb);
}
else if (pcb->flags & TF_ACK_DELAY && pcb->rcv_wnd >= TCP_WND/2) {
/* If we can send a window update such that there is a full
* segment available in the window, do so now. This is sort of
* nagle-like in its goals, and tries to hit a compromise between
* sending acks each time the window is updated, and only sending
* window updates when a timer expires. The "threshold" used
* above (currently TCP_WND/2) can be tuned to be more or less
* aggressive */
tcp_ack_now(pcb);
}
LWIP_DEBUGF(TCP_DEBUG, ("tcp_recved: recveived %"U16_F" bytes, wnd %"U16_F" (%"U16_F").\n",
len, pcb->rcv_wnd, TCP_WND - pcb->rcv_wnd));
}
/**
* This function should be called by the application when it has
* processed the data. The purpose is to advertise a larger window
* when the data has been processed.
*
* @param pcb the tcp_pcb for which data is read
* @param len the amount of bytes that have been read by the application
*/
void tcp_recved(TCP_PCB *pcb, uint16 len)
{
int wnd_inflation;
pcb->rcv_wnd += len;
if (pcb->rcv_wnd > TCP_WND)
{
pcb->rcv_wnd = TCP_WND;
}
wnd_inflation = tcp_update_rcv_ann_wnd(pcb);
/* If the change in the right edge of window is significant (default
* watermark is TCP_WND/2), then send an explicit update now.
* Otherwise wait for a packet to be sent in the normal course of
* events (or more window to be available later) */
if (wnd_inflation >= TCP_WND_UPDATE_THRESHOLD)//tell receive window changed...
{
//printf("tcp_recved:");
tcp_ack_now(pcb);
}
return;
}
/**
* Implements the TCP state machine. Called by tcp_input. In some
* states tcp_receive() is called to receive data. The tcp_seg
* argument will be freed by the caller (tcp_input()) unless the
* recv_data pointer in the pcb is set.
*
* @param pcb the tcp_pcb for which a segment arrived
*
* @note the segment which arrived is saved in global variables, therefore only the pcb
* involved is passed as a parameter to this function
*/
static err_t
tcp_process(struct tcp_pcb *pcb)
{
struct tcp_seg *rseg;
u8_t acceptable = 0;
err_t err;
u8_t accepted_inseq;
err = ERR_OK;
/* Process incoming RST segments. */
if (flags & TCP_RST) {
/* First, determine if the reset is acceptable. */
if (pcb->state == SYN_SENT) {
if (ackno == pcb->snd_nxt) {
acceptable = 1;
}
} else {
if (TCP_SEQ_BETWEEN(seqno, pcb->rcv_nxt,
pcb->rcv_nxt+pcb->rcv_ann_wnd)) {
acceptable = 1;
}
}
if (acceptable) {
LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_process: Connection RESET\n"));
LWIP_ASSERT("tcp_input: pcb->state != CLOSED", pcb->state != CLOSED);
recv_flags = TF_RESET;
pcb->flags &= ~TF_ACK_DELAY;
return ERR_RST;
} else {
LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_process: unacceptable reset seqno %"U32_F" rcv_nxt %"U32_F"\n",
seqno, pcb->rcv_nxt));
LWIP_DEBUGF(TCP_DEBUG, ("tcp_process: unacceptable reset seqno %"U32_F" rcv_nxt %"U32_F"\n",
seqno, pcb->rcv_nxt));
return ERR_OK;
}
}
/* Update the PCB (in)activity timer. */
pcb->tmr = tcp_ticks;
pcb->keep_cnt_sent = 0;
/* Do different things depending on the TCP state. */
switch (pcb->state) {
case SYN_SENT:
LWIP_DEBUGF(TCP_INPUT_DEBUG, ("SYN-SENT: ackno %"U32_F" pcb->snd_nxt %"U32_F" unacked %"U32_F"\n", ackno,
pcb->snd_nxt, ntohl(pcb->unacked->tcphdr->seqno)));
/* received SYN ACK with expected sequence number? */
if ((flags & TCP_ACK) && (flags & TCP_SYN)
&& ackno == ntohl(pcb->unacked->tcphdr->seqno) + 1) {
pcb->snd_buf++;
pcb->rcv_nxt = seqno + 1;
pcb->lastack = ackno;
pcb->snd_wnd = tcphdr->wnd;
pcb->snd_wl1 = seqno - 1; /* initialise to seqno - 1 to force window update */
pcb->state = ESTABLISHED;
/* Parse any options in the SYNACK before using pcb->mss since that
* can be changed by the received options! */
tcp_parseopt(pcb);
#if TCP_CALCULATE_EFF_SEND_MSS
pcb->mss = tcp_eff_send_mss(pcb->mss, &(pcb->remote_ip));
#endif /* TCP_CALCULATE_EFF_SEND_MSS */
/* Set ssthresh again after changing pcb->mss (already set in tcp_connect
* but for the default value of pcb->mss) */
pcb->ssthresh = pcb->mss * 10;
pcb->cwnd = ((pcb->cwnd == 1) ? (pcb->mss * 2) : pcb->mss);
LWIP_ASSERT("pcb->snd_queuelen > 0", (pcb->snd_queuelen > 0));
--pcb->snd_queuelen;
LWIP_DEBUGF(TCP_QLEN_DEBUG, ("tcp_process: SYN-SENT --queuelen %"U16_F"\n", (u16_t)pcb->snd_queuelen));
rseg = pcb->unacked;
pcb->unacked = rseg->next;
/* If there's nothing left to acknowledge, stop the retransmit
timer, otherwise reset it to start again */
if(pcb->unacked == NULL)
pcb->rtime = -1;
else {
pcb->rtime = 0;
pcb->nrtx = 0;
}
tcp_seg_free(rseg);
/* Call the user specified function to call when sucessfully
* connected. */
TCP_EVENT_CONNECTED(pcb, ERR_OK, err);
tcp_ack_now(pcb);
}
/* received ACK? possibly a half-open connection */
else if (flags & TCP_ACK) {
/* send a RST to bring the other side in a non-synchronized state. */
tcp_rst(ackno, seqno + tcplen, &(iphdr->dest), &(iphdr->src),
tcphdr->dest, tcphdr->src);
}
break;
case SYN_RCVD:
if (flags & TCP_ACK &&
!(flags & TCP_RST)) {
/* expected ACK number? */
if (TCP_SEQ_BETWEEN(ackno, pcb->lastack+1, pcb->snd_nxt)) {
u16_t old_cwnd;
pcb->state = ESTABLISHED;
LWIP_DEBUGF(TCP_DEBUG, ("TCP connection established %"U16_F" -> %"U16_F".\n", inseg.tcphdr->src, inseg.tcphdr->dest));
#if LWIP_CALLBACK_API
LWIP_ASSERT("pcb->accept != NULL", pcb->accept != NULL);
#endif
/* Call the accept function. */
TCP_EVENT_ACCEPT(pcb, ERR_OK, err);
if (err != ERR_OK) {
/* If the accept function returns with an error, we abort
* the connection. */
tcp_abort(pcb);
return ERR_ABRT;
}
old_cwnd = pcb->cwnd;
/* If there was any data contained within this ACK,
* we'd better pass it on to the application as well. */
accepted_inseq = tcp_receive(pcb);
pcb->cwnd = ((old_cwnd == 1) ? (pcb->mss * 2) : pcb->mss);
if ((flags & TCP_FIN) && accepted_inseq) {
tcp_ack_now(pcb);
pcb->state = CLOSE_WAIT;
}
}
/* incorrect ACK number */
else {
/* send RST */
tcp_rst(ackno, seqno + tcplen, &(iphdr->dest), &(iphdr->src),
tcphdr->dest, tcphdr->src);
}
}
break;
case CLOSE_WAIT:
/* FALLTHROUGH */
case ESTABLISHED:
accepted_inseq = tcp_receive(pcb);
if ((flags & TCP_FIN) && accepted_inseq) { /* passive close */
tcp_ack_now(pcb);
pcb->state = CLOSE_WAIT;
}
break;
case FIN_WAIT_1:
tcp_receive(pcb);
if (flags & TCP_FIN) {
if (flags & TCP_ACK && ackno == pcb->snd_nxt) {
LWIP_DEBUGF(TCP_DEBUG,
("TCP connection closed %"U16_F" -> %"U16_F".\n", inseg.tcphdr->src, inseg.tcphdr->dest));
tcp_ack_now(pcb);
tcp_pcb_purge(pcb);
TCP_RMV(&tcp_active_pcbs, pcb);
pcb->state = TIME_WAIT;
TCP_REG(&tcp_tw_pcbs, pcb);
} else {
tcp_ack_now(pcb);
pcb->state = CLOSING;
}
} else if (flags & TCP_ACK && ackno == pcb->snd_nxt) {
pcb->state = FIN_WAIT_2;
}
break;
case FIN_WAIT_2:
tcp_receive(pcb);
if (flags & TCP_FIN) {
LWIP_DEBUGF(TCP_DEBUG, ("TCP connection closed %"U16_F" -> %"U16_F".\n", inseg.tcphdr->src, inseg.tcphdr->dest));
tcp_ack_now(pcb);
tcp_pcb_purge(pcb);
TCP_RMV(&tcp_active_pcbs, pcb);
pcb->state = TIME_WAIT;
TCP_REG(&tcp_tw_pcbs, pcb);
}
break;
case CLOSING:
tcp_receive(pcb);
if (flags & TCP_ACK && ackno == pcb->snd_nxt) {
LWIP_DEBUGF(TCP_DEBUG, ("TCP connection closed %"U16_F" -> %"U16_F".\n", inseg.tcphdr->src, inseg.tcphdr->dest));
tcp_ack_now(pcb);
tcp_pcb_purge(pcb);
TCP_RMV(&tcp_active_pcbs, pcb);
pcb->state = TIME_WAIT;
TCP_REG(&tcp_tw_pcbs, pcb);
}
break;
case LAST_ACK:
tcp_receive(pcb);
if (flags & TCP_ACK && ackno == pcb->snd_nxt) {
LWIP_DEBUGF(TCP_DEBUG, ("TCP connection closed %"U16_F" -> %"U16_F".\n", inseg.tcphdr->src, inseg.tcphdr->dest));
/* bugfix #21699: don't set pcb->state to CLOSED here or we risk leaking segments */
recv_flags = TF_CLOSED;
}
break;
default:
break;
}
return ERR_OK;
}
