Remove BufStreamHandle

[bluejekyll]

@djc, I'm just doing a little cleanup. I think there are a few todos in here, will move from draft once I change those.

[codecov]

Codecov Report

Merging #1433 (0757887) into main (0c07d00) will increase coverage by 0.75%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##             main    #1433      +/-   ##
==========================================
+ Coverage   83.70%   84.44%   +0.75%     
==========================================
  Files         167      166       -1     
  Lines       15867    15689     -178     
==========================================
- Hits        13280    13248      -32     
+ Misses       2587     2441     -146     

[djc]

These are really good changes, and thanks for keeping them split into clean commits!

Some style nits follow. One more structural question: I've never really understood why BufDnsStreamHandle needs to carry around the remote_addr when its send() method takes a SerialMessage which already includes a socket address. I feel like we should maybe kill SerialMessage in favor of explicitly returning both the address and the underlying Message where useful. In the current state, it's possible for the address carried around in the SerialMessage to be out of sync with the actual handle/connection used to send it, which is just weird. (This could definitely be addressed in a later PR, just wanted to mention it while I was reviewing your work in this general area.)

[bluejekyll]

Yeah, I was looking at removing the name_server. I think the reasoning behind that was mainly for UdpSocket originally. When reviewing this code I was actually not sure if we should remove name_server from SerialMessage or from the BufDnsStreamHandle it's needed downstream in StreamHandle but it's effectively ignored on these interfaces on initial creation of the message and placement into the StreamHandle.

I will make the other changes you've pointed out and look a little more at the name_server option.

[bluejekyll]

Ok, so I don't see a simple way to remove the name_server field without some significant changes, that are more than I want here.

[djc]

LGTM.