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Add unix domain socket support for Postgres #253

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merged 6 commits into from
Apr 18, 2020

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Nilix007
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@Nilix007 Nilix007 commented Apr 14, 2020

This PR adds unix domain socket support for Postgres. It also changes the default values of multiple connection parameters to match libpq behaviour, e.g. postgres:/// was equivalent to postgres:///postgres@localhost/postgres for sqlx, but now sqlx would connect to the DB via UDS with the current user as username and database name (assuming we're running a Unix).

Current state: Works on my Linux 😆 What kind of tests would you like to see?

Open questions:

  • This PR uses $USER to get the name of the current user. Does this work on all (supported) Unixes? What about Windows? Do we want to be smarter? (e.g. call geteuid and getpwuid)
  • What about TLS over UDS? This is currently not supported.

Fixes #144

@Nilix007 Nilix007 force-pushed the postgres_uds_support branch 2 times, most recently from 999e2ee to 7f195ac Compare April 14, 2020 19:54
@@ -14,15 +13,24 @@ pub struct MaybeTlsStream {

enum Inner {
NotTls(TcpStream),
#[cfg(all(feature = "postgres", unix))]
UnixStream(crate::runtime::UnixStream),
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I don't like how this in MaybeTlsStream. I think it conflates what the type here is doing.

I'd rather something like:

  • A separate Socket (name?) type that is internally an enumeration between UnixStream and TcpStream.

  • This MaybeTlsStream is then generalized around an S type parameter.

Thoughts?

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I don't see much reason to parameterize MaybeTlsStream if the type is always going to be Socket.

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We could call it MaybeUdsStream and reverse the relationship so that MaybeUdsStream is an enumeration between UnixStream and MaybeTlsStream.

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I guess before we get ahead of ourselves here.. is TLS over UDS even a reasonable thing? If it is, we probably need to at least support that with the type sandwhich.

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@abonander abonander Apr 16, 2020

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The wording in the documentation doesn't suggest TLS support at all over the domain socket: https://www.postgresql.org/docs/12/ssl-tcp.html

It doesn't really make sense anyways to encrypt over the UDS because if someone can sniff the traffic on that socket then they can probably also just inspect your process' memory or Postgres' memory/files for juicy secrets (since they'd have to be running on the same machine with elevated privileges already).

// and falls back to postgres@.../postgres
let username = url
.username()
.or_else(|| std::env::var("USER").map(Cow::Owned).ok())
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Perhaps https://crates.io/crates/whoami is a better idea to be more resilient?

.expect("percent-encoded hostname contained non-UTF-8 bytes")
})
.or_else(|| url.param("host"))
.unwrap_or("/var/run/postgresql".into());
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By default we may want to iterate potential locations for the socket and not just hard-code this one.

  • /tmp
  • /var/run/postgresql
  • /private/tmp ( macOS )

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mehcode commented Apr 16, 2020

First off, awesome enhancement here.

What about Windows

Postgres doesn't support UDS on Windows yet. I did see a patch get merged for that due in Postgres 13, but we have some time to think about it.

I'm not sure if Postgres supports named pipes in Windows though. I'd say that's a different improvement if it does.

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mehcode commented Apr 18, 2020

Thanks for getting this started. I'm doing some refactoring of Postgres and want to roll this in. Thanks again. 👍

@mehcode mehcode marked this pull request as ready for review April 18, 2020 21:31
@mehcode mehcode merged commit 57f52ff into launchbadge:master Apr 18, 2020
@Nilix007
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Thank you for building this awesome piece of software 🥇

PS: I've just pushed a couple of changes that piled up for this PR. You might take 'em as inspiration or something: Nilix007/sqlx@postgres_uds_support^^^...Nilix007:postgres_uds_support

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mehcode commented May 6, 2020

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Support Unix Domain Sockets for Postgres
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