Fixed a bug in the TCP state machine. Added a transition from ESTABLISHED to LAST_ACK...

diff --git a/src/net/tcp.c b/src/net/tcp.c
index 097b77d..b84c302 100644 (file)
--- a/src/net/tcp.c
+++ b/src/net/tcp.c
@@ -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;
 
        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 ) {
        /* 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 */
        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 ) ||
 
        /* Start the timer */
        if ( ( conn->tcp_state == TCP_ESTABLISHED && conn->tcp_lstate == TCP_SYN_SENT ) ||


@@ -719,24 +722,22 @@ static int tcp_rx ( struct pk_buff *pkb,
                goto done;
        }
 
                goto done;
        }
 

-

        /* Process TCP header */
        tcphdr = pkb->data;
        tcp_dump ( tcphdr );
 
        /* Verify header length */
        hlen = ( ( tcphdr->hlen & TCP_MASK_HLEN ) / 16 ) * 4;
        /* Process TCP header */
        tcphdr = pkb->data;
        tcp_dump ( tcphdr );
 
        /* Verify header length */
        hlen = ( ( tcphdr->hlen & TCP_MASK_HLEN ) / 16 ) * 4;

+       if ( hlen < sizeof ( *tcphdr ) ) {
+               DBG ( "Bad header length (%d bytes)\n", hlen );
+               rc = -EINVAL;
+               goto done;
+       }
+       /* TODO: Parse TCP options */

        if ( hlen != sizeof ( *tcphdr ) ) {
        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;
-               }
+               DBG ( "Ignoring TCP options\n" );

        }
 
        }
 

-

        /* TODO: Verify checksum */
        
        /* Demux TCP connection */
        /* TODO: Verify checksum */
        
        /* Demux TCP connection */


@@ -828,16 +829,19 @@ static int tcp_rx ( struct pk_buff *pkb,
                /* Unexpected packet */
                goto unexpected;
        case TCP_ESTABLISHED:
                /* Unexpected packet */
                goto unexpected;
        case TCP_ESTABLISHED:

-#if 0

                if ( tcphdr->flags & TCP_FIN ) {
                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;
                        /* FIN consumes one byte */
                        conn->rcv_nxt++;
                        conn->tcp_flags |= TCP_ACK;

-                       /* Send an acknowledgement */
+                       /* Send the packet */

                        goto send_tcp_nomsg;
                }
                        goto send_tcp_nomsg;
                }

-#endif

                /* Packet might contain data */
                break;
        case TCP_FIN_WAIT_1:
                /* 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 ) );
 
        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 ( 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;
                }
                        rc = 0;
                        goto done;
                }

-               /* Advance snd stream */
+               /* Invoke the acked() callback */

                conn->snd_una += acked;
                conn->snd_una += acked;

-               /* Invoke the acked() callback function */

                conn->tcp_op->acked ( conn, acked );
                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;
-               }
-               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;
+       
+       /**
+        * 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 );

                }
                }

-               /* 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 );
 
   send_tcp_nomsg:
        free_pkb ( conn->tx_pkb );