BIND 10 #2749: kill io_utilities.h or make it safe

[BIND 10 Development]

#2749: kill io_utilities.h or make it safe
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            Reporter:  jinmei        |                        Owner:  muks
                Type:  defect        |                       Status:
            Priority:  medium        |  reviewing
           Component:  Unclassified  |                    Milestone:
            Keywords:                |  Sprint-20131015
           Sensitive:  0             |                   Resolution:
         Sub-Project:  Core          |                 CVSS Scoring:
Estimated Difficulty:  3             |              Defect Severity:  N/A
         Total Hours:  0             |  Feature Depending on Ticket:
                                     |          Add Hours to Ticket:  0
                                     |                    Internal?:  0
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Changes (by stephen):

 * owner:  stephen => muks


Comment:

 Reviewed commit 1685d98e142c2b5915d19bf17f4029459a922321

 '''src/bin/dhcp6/dhcp6_srv.cc'''[[BR]]
 generateServerID(): changes are OK, but when reviewing the code it
 occurred to me that if the "iface->getMacLen()" call returns zero, the
 target address of the memcpy() is invalid.  Admittedly the memcpy() should
 not copy anything because the length will be zero, but a !StackOverflow
 answer [http://stackoverflow.com/questions/5243012/is-it-guaranteed-to-be-
 safe-to perform-memcpy0-0-0 here] quotes the C standard indicating that
 arguments to memcpy() must always be valid, even if the size argument is
 zero.

 However, looking at the code in detail reveals that earlier in the
 function the MAC length is checked against MIN_MAC_LEN. (Also,
 isRangeZero() is called which returns "true" if the MAC comprises entirely
 of zeroes or if the length it zero.)  I've changed the comment from "at
 least 8 bytes" to "more than 8 bytes".

 If you're happy with this change, please merge.

-- 
Ticket URL: <http://bind10.isc.org/ticket/2749#comment:16>
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