Error handling questions about beast HOT 6 CLOSED

I believe you get the error_code out of the system_error and when you make the comparison using error_code, the implementation of error_code checks to see that the error_category associated with the error_code is the same as the error_category associated with the enum. Thats what user defined make_error_code is for, so the implementation of error_code can make the comparison. I believe it is okay for enum values from different error categories to overlap. See:
https://github.com/vinniefalco/Beast/blob/master/include/beast/websocket/impl/error.ipp#L16

Now I could be wrong about this, because the whole error_code and system_error thing is highly confusing and not particularly well explained.

Note that for HTTP, only basic_parser_v1 throws custom error codes, the rest will be the errors thrown by asio. http::write and http::async_write will return boost::asio::error::eof if the message indicates that the connection should be closed afterwards. I might change that.

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I've tested my server with junk input and it throws exceptions like "invalid method" (at least that's what an older version of beast did), which definitely aren't boost::asio::error::??? errors, but I can't figure out what error code namespace/name I should be checking for in my boost::system::system_error catch() block. I test for error::eof and error::operation_aborted, for example.

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This should work:

try
{
    ...
}
catch(boost::system::system_error const& se)
{
    if(se.code() == beast::http::parse_error::bad_method)
        std::cerr << "You got a bad method!\n";
    else if(se.code() == boost::asio::error::eof)
        std::cerr << "End of file reached\n";
    else
        std::cerr << "Some other problem\n";
}

Parse error codes are here:
https://github.com/vinniefalco/Beast/blob/master/include/beast/http/parse_error.hpp#L16

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Thanks. That must be relatively new, I don't recall seeing beast::http::parse_error::bad_method anywhere.

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Ah yes, you're right about that. When Beast was using the nodejs http-parser, it had an error_category that pulled its strings from there:
https://github.com/vinniefalco/Beast/blob/4cfa1d5cd34533caf4930455c6d3817b3bd00e89/include/beast/http/detail/error.hpp#L28

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There's a Gitter chat room for Beast available now:

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