bug fixes from Fujitsu (bug 21)

Note: this fix does not solve the issue with how
this buffer is used in this function, but I'm not
sure this code is used at all (Cédric Roux).

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bug 21

Ttile:
PAYLOAD_MAX=1500, so this coding results in index overflow.
Additionally, operator "!=" just compairs something, this
coding is meaningless.

Bug Location:
buffer[PAYLOAD_MAX] != '\0';

Note:
Detected by CppCheck
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