asyncio sock_recv blocks on ssl sockets.

[blackblood]

BPO	37404
Nosy	@tiran, @asvetlov, @1st1, @miss-islington, @blackblood, @idomic
PRs	bpo-37404: Raising value error if an SSLSocket is passed to asyncio functions #14457 bpo-37404: Raising value error if an SSLSocket is passed to asyncio functions #16457 [3.7] bpo-37404: Raising value error if an SSLSocket is passed to asyncio functions (GH-16457) #17495 [3.8] bpo-37404: Raising value error if an SSLSocket is passed to asyncio functions (GH-16457) #17496 bpo-37404: Fix check for ssl.SSLSocket #17526
Files	server_client: Server/Client Code to replicate the issue. Note: You'll have to create the certificate.pem and key.pem files

^{Note: these values reflect the state of the issue at the time it was migrated and might not reflect the current state.}

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GitHub fields:

assignee = 'https://github.com/tiran'
closed_at = <Date 2020-02-03.10:16:45.842>
created_at = <Date 2019-06-25.19:36:21.829>
labels = ['easy', 'expert-SSL', 'type-bug', '3.8', '3.9', '3.7', 'expert-asyncio']
title = 'asyncio sock_recv blocks on ssl sockets.'
updated_at = <Date 2020-02-03.10:16:45.841>
user = 'https://github.com/blackblood'

bugs.python.org fields:

activity = <Date 2020-02-03.10:16:45.841>
actor = 'asvetlov'
assignee = 'christian.heimes'
closed = True
closed_date = <Date 2020-02-03.10:16:45.842>
closer = 'asvetlov'
components = ['asyncio', 'SSL']
creation = <Date 2019-06-25.19:36:21.829>
creator = 'AkshayTakkar'
dependencies = []
files = ['48437']
hgrepos = []
issue_num = 37404
keywords = ['patch', 'easy', 'newcomer friendly']
message_count = 11.0
messages = ['346550', '346552', '346597', '346598', '346599', '353444', '357971', '357972', '357973', '358086', '361236']
nosy_count = 6.0
nosy_names = ['christian.heimes', 'asvetlov', 'yselivanov', 'miss-islington', 'AkshayTakkar', 'Ido Michael']
pr_nums = ['14457', '16457', '17495', '17496', '17526']
priority = 'normal'
resolution = 'fixed'
stage = 'resolved'
status = 'closed'
superseder = None
type = 'behavior'
url = 'https://bugs.python.org/issue37404'
versions = ['Python 3.7', 'Python 3.8', 'Python 3.9']

[blackblood]

I'm working on a server that uses sock_recv from asyncio.
await sock_recv(socket, n) never returns if socket is wrapped in ssl using the wrap_socket function from the ssl module.
I think the problem stated in this stackoverflow question could be the reason: https://stackoverflow.com/questions/40346619/behavior-of-pythons-select-with-partial-recv-on-ssl-socket

[tiran]

You can't use sock_recv() with a wrapped SSL socket. A SSLSocket behaves differently because there is user-level buffering. The connection operates on TLS frames and only hands off data after it has been decrypted and verified. asyncio uses wrap_bio().

[blackblood]

Can you please elaborate on how to get around this issue?

[asvetlov]

Use asyncio transports or streams.
sock_recv() is a low-level API with a very limited audience.

wrapped ssl socket provides a synchronous interface only.

Perhaps we should raise an exception if SSLSocket is passed into asyncio functions.

[blackblood]

Ah, I see. Yes, raising an exception would probably be very useful. Thanks for the info.

[idomic]

Fixed this issue since the CLA of the past user wasn't signed.

Added a check for the socket type in each of the methods:
sock_recv, sock_recv_into, sock_sendall, sock_connect, sock_accept.

PR: #60661

[miss-islington]

New changeset 892f9e0 by Miss Islington (bot) (idomic) in branch 'master':
bpo-37404: Raising value error if an SSLSocket is passed to asyncio functions (GH-16457)
892f9e0

[asvetlov]

New changeset 930cef2 by Andrew Svetlov in branch '3.8':
[3.8] bpo-37404: Raising value error if an SSLSocket is passed to asyncio functions (GH-16457) (bpo-17496)
930cef2

[miss-islington]

New changeset a85066d by Miss Islington (bot) in branch '3.7':
bpo-37404: Raising value error if an SSLSocket is passed to asyncio functions (GH-16457)
a85066d

[tiran]

The patch broke Python builds without ssl support and caused a minor performance regression in hot paths. I changed the code to only perform the check in debug mode.

[idomic]

Sorry it broke the version, what could I have done to avoid this?
Also can we close this issue?