restrict SEGV

i use webserver and stress to it by apache bench.

give -n 10000 and -c 1000 options to ab and then webserver was crashed with SEGV.

i was tracking with gdb and recognizing http.h doesnt care socket read error.

so, i fix http.h to care socket read error and set http response code as 500 when this error occured.
and webserver doesnt down now.

thank you.