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    [DCCP]: Support for partial checksums (RFC 4340, sec. 9.2) · 6f4e5fff
    Gerrit Renker 提交于
    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: NGerrit Renker <gerrit@erg.abdn.ac.uk>
    Signed-off-by: NArnaldo Carvalho de Melo <acme@mandriva.com>
    6f4e5fff
ipv4.c 28.5 KB