diff options
| author | Michael Brown <mcb30@ipxe.org> | 2014-03-04 13:10:07 +0000 |
|---|---|---|
| committer | Michael Brown <mcb30@ipxe.org> | 2014-03-04 13:13:54 +0000 |
| commit | 6414b5ca036ade7545eb0c309c66731fced6e055 (patch) | |
| tree | dd73109b6fbbff5e176b87c30df744665595cafb /src/net | |
| parent | db67de6f31a062dc1995d4561be83cd51609d6c4 (diff) | |
| download | ipxe-6414b5ca036ade7545eb0c309c66731fced6e055.tar.gz | |
[tcpip] Provide tcpip_mtu() to determine the maximum transmission unit
Provide the function tcpip_mtu() to allow external code to determine
the (transport-layer) maximum transmission unit for a given socket
address.
Signed-off-by: Michael Brown <mcb30@ipxe.org>
Diffstat (limited to 'src/net')
| -rw-r--r-- | src/net/ipv4.c | 1 | ||||
| -rw-r--r-- | src/net/ipv6.c | 1 | ||||
| -rw-r--r-- | src/net/tcpip.c | 29 |
3 files changed, 31 insertions, 0 deletions
diff --git a/src/net/ipv4.c b/src/net/ipv4.c index 8bda5c86..c5cfd134 100644 --- a/src/net/ipv4.c +++ b/src/net/ipv4.c @@ -621,6 +621,7 @@ struct net_protocol ipv4_protocol __net_protocol = { struct tcpip_net_protocol ipv4_tcpip_protocol __tcpip_net_protocol = { .name = "IPv4", .sa_family = AF_INET, + .header_len = sizeof ( struct iphdr ), .tx = ipv4_tx, .netdev = ipv4_netdev, }; diff --git a/src/net/ipv6.c b/src/net/ipv6.c index 6f2e9477..f753751d 100644 --- a/src/net/ipv6.c +++ b/src/net/ipv6.c @@ -988,6 +988,7 @@ struct net_protocol ipv6_protocol __net_protocol = { struct tcpip_net_protocol ipv6_tcpip_protocol __tcpip_net_protocol = { .name = "IPv6", .sa_family = AF_INET6, + .header_len = sizeof ( struct ipv6_header ), .tx = ipv6_tx, .netdev = ipv6_netdev, }; diff --git a/src/net/tcpip.c b/src/net/tcpip.c index 6fac8c52..4bcbe64b 100644 --- a/src/net/tcpip.c +++ b/src/net/tcpip.c @@ -6,6 +6,7 @@ #include <ipxe/iobuf.h> #include <ipxe/tables.h> #include <ipxe/ipstat.h> +#include <ipxe/netdevice.h> #include <ipxe/tcpip.h> /** @file @@ -123,6 +124,34 @@ struct net_device * tcpip_netdev ( struct sockaddr_tcpip *st_dest ) { } /** + * Determine maximum transmission unit + * + * @v st_dest Destination address + * @ret mtu Maximum transmission unit + */ +size_t tcpip_mtu ( struct sockaddr_tcpip *st_dest ) { + struct tcpip_net_protocol *tcpip_net; + struct net_device *netdev; + size_t mtu; + + /* Find appropriate network-layer protocol */ + tcpip_net = tcpip_net_protocol ( st_dest ); + if ( ! tcpip_net ) + return 0; + + /* Find transmitting network device */ + netdev = tcpip_net->netdev ( st_dest ); + if ( ! netdev ) + return 0; + + /* Calculate MTU */ + mtu = ( netdev->max_pkt_len - netdev->ll_protocol->ll_header_len - + tcpip_net->header_len ); + + return mtu; +} + +/** * Calculate continued TCP/IP checkum * * @v partial Checksum of already-summed data, in network byte order |