diff options
| -rw-r--r-- | src/include/ipxe/tcp.h | 10 | ||||
| -rw-r--r-- | src/net/tcp.c | 15 |
2 files changed, 14 insertions, 11 deletions
diff --git a/src/include/ipxe/tcp.h b/src/include/ipxe/tcp.h index eb4b7b2..9baa639 100644 --- a/src/include/ipxe/tcp.h +++ b/src/include/ipxe/tcp.h @@ -330,16 +330,6 @@ struct tcp_options { #define TCP_PATH_MTU \ ( 1280 - 40 /* IPv6 */ - 20 /* TCP */ - 12 /* TCP timestamp */ ) -/** - * Advertised TCP MSS - * - * We currently hardcode this to a reasonable value and hope that the - * sender uses path MTU discovery. The alternative is breaking the - * abstraction layer so that we can find out the MTU from the IP layer - * (which would have to find out from the net device layer). - */ -#define TCP_MSS 1460 - /** TCP maximum segment lifetime * * Currently set to 2 minutes, as per RFC 793. diff --git a/src/net/tcp.c b/src/net/tcp.c index 7087203..548bd4d 100644 --- a/src/net/tcp.c +++ b/src/net/tcp.c @@ -43,6 +43,8 @@ struct tcp_connection { struct sockaddr_tcpip peer; /** Local port */ unsigned int local_port; + /** Maximum segment size */ + size_t mss; /** Current TCP state */ unsigned int tcp_state; @@ -250,6 +252,7 @@ static int tcp_open ( struct interface *xfer, struct sockaddr *peer, struct sockaddr_tcpip *st_peer = ( struct sockaddr_tcpip * ) peer; struct sockaddr_tcpip *st_local = ( struct sockaddr_tcpip * ) local; struct tcp_connection *tcp; + size_t mtu; int port; int rc; @@ -271,6 +274,16 @@ static int tcp_open ( struct interface *xfer, struct sockaddr *peer, INIT_LIST_HEAD ( &tcp->rx_queue ); memcpy ( &tcp->peer, st_peer, sizeof ( tcp->peer ) ); + /* Calculate MSS */ + mtu = tcpip_mtu ( &tcp->peer ); + if ( ! mtu ) { + DBGC ( tcp, "TCP %p has no route to %s\n", + tcp, sock_ntoa ( peer ) ); + rc = -ENETUNREACH; + goto err; + } + tcp->mss = ( mtu - sizeof ( struct tcp_header ) ); + /* Bind to local port */ port = tcpip_bind ( st_local, tcp_port_available ); if ( port < 0 ) { @@ -552,7 +565,7 @@ static int tcp_xmit ( struct tcp_connection *tcp ) { mssopt = iob_push ( iobuf, sizeof ( *mssopt ) ); mssopt->kind = TCP_OPTION_MSS; mssopt->length = sizeof ( *mssopt ); - mssopt->mss = htons ( TCP_MSS ); + mssopt->mss = htons ( tcp->mss ); wsopt = iob_push ( iobuf, sizeof ( *wsopt ) ); wsopt->nop = TCP_OPTION_NOP; wsopt->wsopt.kind = TCP_OPTION_WS; |