fix read/write loop may hang in some situation.

[DrmagicE]

fix #177

[codecov-commenter]

Codecov Report

Merging #186 (4db09d7) into master (9b6e597) will decrease coverage by 0.03%.
The diff coverage is 22.22%.

@@            Coverage Diff             @@
##           master     #186      +/-   ##
==========================================
- Coverage   42.77%   42.74%   -0.04%     
==========================================
  Files          63       63              
  Lines        6347     6354       +7     
==========================================
+ Hits         2715     2716       +1     
- Misses       3304     3310       +6     
  Partials      328      328              

Impacted Files	Coverage Δ
server/server.go	13.86% <0.00%> (-0.11%)	⬇️
plugin/federation/federation.go	61.06% <100.00%> (ø)
server/client.go	44.87% <100.00%> (+0.11%)	⬆️

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