[GitHub] nickva edited a comment on issue #1810: Requests return 400 Bad Request when URL length exceeds 1460 characters

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nickva edited a comment on issue #1810: Requests return 400 Bad Request when URL length exceeds 1460 characters
URL: https://github.com/apache/couchdb/issues/1810#issuecomment-447152497
 
 
   Hi @dianabarsan,
   
   Thank you for the bug report and excellent analysis.
   
   You're absolutely correct, `chttpd.server_option = [{recbuf, undefined}]).` ends up not setting recbuf value, which means Erlang userland buffer gets a default value of 1460 (when recbuf is set so is the userland buffer).
   
   This buffer size limit combined with a long-standing bug in Erlang's `{packet, http}` parser ends crashing the socket receive code with an `emsgsize` error.
   
   It's not possible to set the buffer size in mochiweb current, so I will make a PR request to fix that.
   
   Notice:
   
   ```
   30> f(), SockInfo = fun(S) -> inet:getopts(S, [recbuf, buffer]) end, {ok, LS} = gen_tcp:listen(0, [{recbuf, 8192}]), LRes = SockInfo(LS).
   {ok,[{recbuf,8192},{buffer,8192}]}
   ```
   
   ```
   31> f(), SockInfo = fun(S) -> inet:getopts(S, [recbuf, buffer]) end, {ok, LS} = gen_tcp:listen(0, []), LRes = SockInfo(LS).
   {ok,[{recbuf,131072},{buffer,1460}]}
   ```

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