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Send RST packets when we get a non-matching connection, or receive an 

out-of-range ACK.
This commit is contained in:
Michael Brown 2007-01-03 22:21:59 +00:00
parent eea1167a85
commit b0daa99dce
1 changed files with 51 additions and 9 deletions
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60
src/net/tcp.c
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@ -425,6 +425,49 @@ static void tcp_expired ( struct retry_timer *timer, int over ) {
}
}
/**
* Send RST response to incoming packet
*
* @v in_tcphdr TCP header of incoming packet
* @ret rc Return status code
*/
static int tcp_send_reset ( struct tcp_connection *conn,
struct tcp_header *in_tcphdr ) {
struct pk_buff *pkb;
struct tcp_header *tcphdr;
/* Allocate space for dataless TX buffer */
pkb = alloc_pkb ( MAX_HDR_LEN );
if ( ! pkb ) {
DBGC ( conn, "TCP %p could not allocate data buffer\n", conn );
return -ENOMEM;
}
pkb_reserve ( pkb, MAX_HDR_LEN );
/* Construct RST response */
tcphdr = pkb_push ( pkb, sizeof ( *tcphdr ) );
memset ( tcphdr, 0, sizeof ( *tcphdr ) );
tcphdr->src = in_tcphdr->dest;
tcphdr->dest = in_tcphdr->src;
tcphdr->seq = in_tcphdr->ack;
tcphdr->ack = in_tcphdr->seq;
tcphdr->hlen = ( ( sizeof ( *tcphdr ) / 4 ) << 4 );
tcphdr->flags = ( TCP_RST | TCP_ACK );
tcphdr->win = htons ( TCP_WINDOW_SIZE );
tcphdr->csum = tcpip_chksum ( pkb->data, pkb_len ( pkb ) );
/* Dump header */
DBGC ( conn, "TCP %p TX %d->%d %08lx..%08lx %08lx %4zd",
conn, ntohs ( tcphdr->src ), ntohs ( tcphdr->dest ),
ntohl ( tcphdr->seq ), ( ntohl ( tcphdr->seq ) ),
ntohl ( tcphdr->ack ), 0 );
tcp_dump_flags ( conn, tcphdr->flags );
DBGC ( conn, "\n" );
/* Transmit packet */
return tcpip_tx ( pkb, &tcp_protocol, &conn->peer, &tcphdr->csum );
}
/**
* Identify TCP connection by local port number
*
@ -700,18 +743,20 @@ static int tcp_rx ( struct pk_buff *pkb,
tcp_dump_flags ( conn, tcphdr->flags );
DBGC ( conn, "\n" );
/* If no connection was found, create dummy connection for
* sending RST
*/
#warning "Handle non-matched connections"
/* If no connection was found, send RST */
if ( ! conn ) {
tcp_send_reset ( conn, tcphdr );
rc = -ENOTCONN;
goto done;
}
/* Handle ACK, if present */
if ( flags & TCP_ACK )
tcp_rx_ack ( conn, ack, win );
if ( flags & TCP_ACK ) {
if ( ( rc = tcp_rx_ack ( conn, ack, win ) ) != 0 ) {
tcp_send_reset ( conn, tcphdr );
goto done;
}
}
/* Handle SYN, if present */
if ( flags & TCP_SYN ) {
@ -773,9 +818,6 @@ static int tcp_bind ( struct tcp_connection *conn, uint16_t local_port ) {
struct tcp_connection *existing;
static uint16_t try_port = 1024;
#warning "Fix the port re-use bug"
try_port = random();
/* If no port specified, find the first available port */
if ( ! local_port ) {
for ( ; try_port ; try_port++ ) {