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[tcp] Allow sufficient headroom for TCP headers

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TCP currently neglects to allow sufficient space for its own headers
when allocating I/O buffers.  This problem is masked by the fact that
the maximum link-layer header size (802.11) is substantially larger
than the common Ethernet link-layer header.

Fix by allowing sufficient space for any TCP headers, as well as the
network-layer and link-layer headers.

Reported-by: Scott K Logan <logans@cottsay.net>
Debugged-by: Scott K Logan <logans@cottsay.net>
Tested-by: Scott K Logan <logans@cottsay.net>
Signed-off-by: Michael Brown <mcb30@ipxe.org>
This commit is contained in:
Michael Brown 2011-09-19 15:48:57 +01:00
parent 1691cf50bc
commit 469bd11f39
2 changed files with 14 additions and 4 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

10
src/include/ipxe/tcp.h
View File

@ -308,6 +308,16 @@ struct tcp_options {
*/
#define TCP_MSL ( 2 * 60 * TICKS_PER_SEC )
/**
* TCP maximum header length
*
*/
#define TCP_MAX_HEADER_LEN \
( MAX_LL_NET_HEADER_LEN + \
sizeof ( struct tcp_header ) + \
sizeof ( struct tcp_mss_option ) + \
sizeof ( struct tcp_timestamp_padded_option ) )
/**
* Compare TCP sequence numbers
*

8
src/net/tcp.c
View File

@ -509,14 +509,14 @@ static int tcp_xmit ( struct tcp_connection *tcp ) {
start_timer ( &tcp->timer );
/* Allocate I/O buffer */
iobuf = alloc_iob ( len + MAX_LL_NET_HEADER_LEN );
iobuf = alloc_iob ( len + TCP_MAX_HEADER_LEN );
if ( ! iobuf ) {
DBGC ( tcp, "TCP %p could not allocate iobuf for %08x..%08x "
"%08x\n", tcp, tcp->snd_seq, ( tcp->snd_seq + seq_len ),
tcp->rcv_ack );
return -ENOMEM;
}
iob_reserve ( iobuf, MAX_LL_NET_HEADER_LEN );
iob_reserve ( iobuf, TCP_MAX_HEADER_LEN );
/* Fill data payload from transmit queue */
tcp_process_tx_queue ( tcp, len, iobuf, 0 );
@ -653,14 +653,14 @@ static int tcp_xmit_reset ( struct tcp_connection *tcp,
int rc;
/* Allocate space for dataless TX buffer */
iobuf = alloc_iob ( MAX_LL_NET_HEADER_LEN );
iobuf = alloc_iob ( TCP_MAX_HEADER_LEN );
if ( ! iobuf ) {
DBGC ( tcp, "TCP %p could not allocate iobuf for RST "
"%08x..%08x %08x\n", tcp, ntohl ( in_tcphdr->ack ),
ntohl ( in_tcphdr->ack ), ntohl ( in_tcphdr->seq ) );
return -ENOMEM;
}
iob_reserve ( iobuf, MAX_LL_NET_HEADER_LEN );
iob_reserve ( iobuf, TCP_MAX_HEADER_LEN );
/* Construct RST response */
tcphdr = iob_push ( iobuf, sizeof ( *tcphdr ) );