So the delegate can close the socket instead of keeping sending data.
Read EOF or h2 half-closed (remote) state was introduced in
https://codereview.chromium.org/129543002. But StreamSocket doesnt
really supports a half closed state, so upon a read EOF the only sane
action is to close the socket immediately even if in theory more send
is possible.
Per RFC 7540#6.4:
However, after sending the RST_STREAM, the sending endpoint MUST be
prepared to receive and process additional frames sent on the stream
that might have been sent by the peer prior to the arrival of the
RST_STREAM.
In the socket system, only WebSocket sockets are allowed to tunnel
through HTTP/1 proxies. "Raw" sockets in the normal socket pool don't
have it, and their CONNECT headers are not sent, instead the raw
payload is sent as-is to the HTTP/1 proxy, breaking the proxying.
The socket system works like this:
- HTTP sockets via HTTP/1 proxies: normal pool, no tunneling.
- HTTPS sockets via HTTP/1 proxies: normal pool, no tunneling,
but does its own proxy encapsulation.
- WS sockets via HTTP/1 proxies: WS pool, tunneling.
In Naive, we need the normal pool because the WS pool has some extra
restrictions but we also need tunneling to produce a client socket
with proxy tunneling built in.
Therefore force tunneling for all sockets and have them always send
CONNECT headers. This will otherwise break regular HTTP client sockets
via HTTP/1 proxies, but as we don't use this combination, it is ok.
