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Fixed a bug in the TCP state machine. Added a transition from ESTABLISHED to LAST_ACK on receiving a FIN,ACK

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This commit is contained in:
Nikhil Chandru Rao 2006-08-19 16:14:53 +00:00
parent d1d334b8e1
commit dccb8358bd
1 changed files with 47 additions and 58 deletions
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105
src/net/tcp.c
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@ -329,6 +329,8 @@ void tcp_trans ( struct tcp_connection *conn, int nxt_state ) {
conn->tcp_lstate = conn->tcp_state;
conn->tcp_state = nxt_state;
DBG ( "Transition from %s to %s\n", tcp_states[conn->tcp_lstate], tcp_states[conn->tcp_state] );
/* TODO: Check if this check is required */
if ( conn->tcp_lstate == conn->tcp_state ||
conn->tcp_state == TCP_INVALID ) {
@ -682,6 +684,7 @@ int tcp_send ( struct tcp_connection *conn, const void *data, size_t len ) {
tcphdr->csum = tcpip_chksum ( pkb->data, pkb_len ( pkb ) );
/* Dump the TCP header */
tcp_dump ( tcphdr );
/* Start the timer */
if ( ( conn->tcp_state == TCP_ESTABLISHED && conn->tcp_lstate == TCP_SYN_SENT ) ||
@ -719,23 +722,21 @@ static int tcp_rx ( struct pk_buff *pkb,
goto done;
}
/* Process TCP header */
tcphdr = pkb->data;
tcp_dump ( tcphdr );
/* Verify header length */
hlen = ( ( tcphdr->hlen & TCP_MASK_HLEN ) / 16 ) * 4;
if ( hlen != sizeof ( *tcphdr ) ) {
if ( hlen == sizeof ( *tcphdr ) + 4 ) {
DBG ( "TCP options sent\n" );
} else {
DBG ( "Bad header length (%d bytes)\n", hlen );
rc = -EINVAL;
goto done;
}
if ( hlen < sizeof ( *tcphdr ) ) {
DBG ( "Bad header length (%d bytes)\n", hlen );
rc = -EINVAL;
goto done;
}
/* TODO: Parse TCP options */
if ( hlen != sizeof ( *tcphdr ) ) {
DBG ( "Ignoring TCP options\n" );
}
/* TODO: Verify checksum */
@ -828,16 +829,19 @@ static int tcp_rx ( struct pk_buff *pkb,
/* Unexpected packet */
goto unexpected;
case TCP_ESTABLISHED:
#if 0
if ( tcphdr->flags & TCP_FIN ) {
tcp_trans ( conn, TCP_CLOSE_WAIT );
if ( tcphdr->flags & TCP_ACK ) {
tcp_trans ( conn, TCP_LAST_ACK );
conn->tcp_flags |= TCP_FIN;
} else {
tcp_trans ( conn, TCP_CLOSE_WAIT );
}
/* FIN consumes one byte */
conn->rcv_nxt++;
conn->tcp_flags |= TCP_ACK;
/* Send an acknowledgement */
/* Send the packet */
goto send_tcp_nomsg;
}
#endif
/* Packet might contain data */
break;
case TCP_FIN_WAIT_1:
@ -901,60 +905,45 @@ static int tcp_rx ( struct pk_buff *pkb,
assert ( ( tcphdr->flags & TCP_ACK ) ||
pkb_len ( pkb ) > sizeof ( *tcphdr ) );
/* Check for new data */
toack = pkb_len ( pkb ) - hlen;
if ( toack > 0 ) {
/* Check if expected sequence number */
if ( conn->rcv_nxt == ntohl ( tcphdr->seq ) ) {
conn->rcv_nxt += toack;
conn->tcp_op->newdata ( conn, pkb->data + hlen,
toack );
} else {
DBG ( "Unexpected sequence number %lx (wanted %lx)\n",
ntohl ( tcphdr->seq ), conn->rcv_nxt );
}
/* Acknowledge new data */
conn->tcp_flags |= TCP_ACK;
if ( !( tcphdr->flags & TCP_ACK ) ) {
goto send_tcp_nomsg;
}
}
/* Process ACK */
/**
* Check if the received packet ACKs sent data
*/
if ( tcphdr->flags & TCP_ACK ) {
acked = ntohl ( tcphdr->ack ) - conn->snd_una;
if ( acked < 0 ) { /* TODO: Replace all uint32_t arith */
DBG ( "Previously ACKed (%d)\n", tcphdr->ack );
if ( acked < 0 ) {
/* Packet ACKs previously ACKed data */
DBG ( "Previously ACKed data %lx\n",
ntohl ( tcphdr->ack ) );
rc = 0;
goto done;
}
/* Advance snd stream */
/* Invoke the acked() callback */
conn->snd_una += acked;
/* Invoke the acked() callback function */
conn->tcp_op->acked ( conn, acked );
/* Invoke the senddata() callback function */
tcp_senddata ( conn );
}
/* If the connection is in ESTABLISHED and it receives a FIN */
if ( conn->tcp_state == ESTABLISHED && ( tcphdr->flags & TCP_FIN ) ) {
if ( tcphdr->flags & TCP_ACK ) {
tcp_trans ( conn, TCP_LAST_ACK );
goto send_tcp_nomsg;
/**
* Check if packet contains new data
*/
toack = pkb_len ( pkb ) - hlen;
if ( toack >= 0 ) {
/* Check the sequence number */
if ( conn->rcv_nxt == ntohl ( tcphdr->seq ) ) {
conn->rcv_nxt += toack;
conn->tcp_op->newdata ( conn,
pkb->data + hlen, toack );
} else {
DBG ( "Unexpected sequence number %lx (wanted %lx)\n",
ntohl ( tcphdr->ack ), conn->rcv_nxt );
}
tcp_trans ( conn, TCP_CLOSE_WAIT );
// conn->tcp_op->closed ( conn, CONN_SNDCLOSE );
conn->rcv_nxt++;
if ( ! ( tcphdr->flags & TCP_ACK ) ) {
conn->tcp_flags |= TCP_ACK;
/* Send an acknowledgement */
goto send_tcp_nomsg;
}
/* Otherwise, the packet has been ACKed already */
conn->tcp_flags |= TCP_ACK;
}
rc = 0;
goto done;
/**
* Send data
*/
tcp_senddata ( conn );
return 0;
send_tcp_nomsg:
free_pkb ( conn->tx_pkb );