Support authentication response are multiple frames

[liukun-msft]

Fix #5124

Issue

When using proxy configuration, it is possible that the HTTP response does not come in a single frame, but multiple frames.
This will cause the authorization with the proxy failure with execption.

Changes

• Add a new interface ProxyResponse and implementation ProxyResponseImpl to save multiple frames into one response.
• Add logic to read multiple frames in ProxyImpl and update validation logic by getting infomation from ProxyResponse header.
• Remove class ProxyResponseResult since all information are already saved in ProxyResponse.
• Update DigestProxyChallengeProcessorImpl authentication logic since now we get types from header rather than error message.
• Reduce buffer size PROXY_HANDSHAKE_BUFFER_SIZE from 8 * 1024 to 4 * 1024.
• Change related UT test.

Test scenarios

• BASIC with response over 4K
• Digest with response over 4K
• BASIC with response less 4K
• Digest with response less 4K

[conniey]

Thanks! Looks great. :D Just a few comments.

[liukun-msft]

Reduced buffer size PROXY_HANDSHAKE_BUFFER_SIZE from 8 * 1024 to 4 * 1024.

[conniey]

Thanks! It looks good to me. I pinged @JamesBirdsall to see if he could take a quick look since they also use this library.

[conniey]

Is there a reason we removed all of these 2xx status code test cases?

[liukun-msft]

We changed the validation for proxy response. Now we only assume 200 Connection Established is the successful response.

 return status.getStatusCode() == 200
                && SUPPORTED_VERSIONS.contains(status.getProtocolVersion())
                && CONNECTION_ESTABLISHED.equalsIgnoreCase(status.getReason());

Previously, we use the pattern to do this validation. So the test verify all 2xx status code.

Pattern.compile("^http/1\\.(0|1) (?<statusCode>2[0-9]{2})", Pattern.CASE_INSENSITIVE);

Do you think we need add back and consider other 2xx status as successful response?

[JamesBirdsall]

Looks reasonable to me!