[DCCP]: Support for partial checksums (RFC 4340, sec. 9.2)
This patch does the following:
a) introduces variable-length checksums as specified in [RFC 4340, sec. 9.2]
b) provides necessary socket options and documentation as to how to use them
c) basic support and infrastructure for the Minimum Checksum Coverage feature
[RFC 4340, sec. 9.2.1]: acceptability tests, user notification and user
interface
In addition, it
(1) fixes two bugs in the DCCPv4 checksum computation:
* pseudo-header used checksum_len instead of skb->len
* incorrect checksum coverage calculation based on dccph_x
(2) removes dccp_v4_verify_checksum() since it reduplicates code of the
checksum computation; code calling this function is updated accordingly.
(3) now uses skb_checksum(), which is safer than checksum_partial() if the
sk_buff has is a non-linear buffer (has pages attached to it).
(4) fixes an outstanding TODO item:
* If P.CsCov is too large for the packet size, drop packet and return.
The code has been tested with applications, the latest version of tcpdump now
comes with support for partial DCCP checksums.
Signed-off-by: Gerrit Renker <gerrit@erg.abdn.ac.uk>
Signed-off-by: Arnaldo Carvalho de Melo <acme@mandriva.com>
diff --git a/include/linux/dccp.h b/include/linux/dccp.h
index 90d04ff..0502dfa 100644
--- a/include/linux/dccp.h
+++ b/include/linux/dccp.h
@@ -183,6 +183,7 @@
DCCPF_ACK_RATIO = 5,
DCCPF_SEND_ACK_VECTOR = 6,
DCCPF_SEND_NDP_COUNT = 7,
+ DCCPF_MIN_CSUM_COVER = 8,
/* 10-127 reserved */
DCCPF_MIN_CCID_SPECIFIC = 128,
DCCPF_MAX_CCID_SPECIFIC = 255,
@@ -200,6 +201,8 @@
#define DCCP_SOCKOPT_SERVICE 2
#define DCCP_SOCKOPT_CHANGE_L 3
#define DCCP_SOCKOPT_CHANGE_R 4
+#define DCCP_SOCKOPT_SEND_CSCOV 10
+#define DCCP_SOCKOPT_RECV_CSCOV 11
#define DCCP_SOCKOPT_CCID_RX_INFO 128
#define DCCP_SOCKOPT_CCID_TX_INFO 192
@@ -450,6 +453,8 @@
* @dccps_timestamp_echo - latest timestamp received on a TIMESTAMP option
* @dccps_packet_size - Set thru setsockopt
* @dccps_role - Role of this sock, one of %dccp_role
+ * @dccps_pcslen - sender partial checksum coverage (via sockopt)
+ * @dccps_pcrlen - receiver partial checksum coverage (via sockopt)
* @dccps_ndp_count - number of Non Data Packets since last data packet
* @dccps_hc_rx_ackvec - rx half connection ack vector
* @dccps_xmit_timer - timer for when CCID is not ready to send
@@ -474,6 +479,8 @@
__u32 dccps_packet_size;
__u16 dccps_l_ack_ratio;
__u16 dccps_r_ack_ratio;
+ __u16 dccps_pcslen;
+ __u16 dccps_pcrlen;
unsigned long dccps_ndp_count;
__u32 dccps_mss_cache;
struct dccp_minisock dccps_minisock;