[network] Fix packet buffer size calculation.
[network] Fix packet buffer size calculation.

fhijaz/Graphite,fhijaz/Graphite,mit-carbon/Graphite,nkawahara/Graphite,mit-carbon/Graphite-Cycle-Level,mit-carbon/Graphite-Cycle-Level,mit-carbon/Graphite,fhijaz/Graphite,nkawahara/Graphite,victorisildur/Graphite,8l/Graphite,mit-carbon/Graphite,victorisildur/Graphite,mit-carbon/Graphite-Cycle-Level,fhijaz/Graphite,victorisildur/Graphite,8l/Graphite,victorisildur/Graphite,mit-carbon/Graphite-Cycle-Level,nkawahara/Graphite,mit-carbon/Graphite,8l/Graphite,8l/Graphite,nkawahara/Graphite