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feat: Get tcp_info structure #2615

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daaa9af
feat: Get `tcp_info` structure
b-parikh Mar 19, 2025
7e6cd7e
chore: CHANGELOG entry for TCP_INFO sockopt addition
b-parikh Mar 19, 2025
46c7bb0
Update changelog with pull request 2615
b-parikh Mar 24, 2025
7cb4426
Revert "chore: CHANGELOG entry for TCP_INFO sockopt addition"
b-parikh Mar 30, 2025
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2 changes: 2 additions & 0 deletions CHANGELOG.md
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Original file line number Diff line number Diff line change
Expand Up @@ -1960,6 +1960,8 @@ This project adheres to [Semantic Versioning](https://semver.org/).
- Added `SIGINFO` in `::nix::sys::signal` for the _macos_ target as well as
`SIGPWR` and `SIGSTKFLT` in `::nix::sys::signal` for non-_macos_ targets.
([#361](https://github.com/nix-rust/nix/pull/361))
- Added `TCP_INFO` sockopt to read TCP socket information on _linux_.
([#2615](https://github.com/nix-rust/nix/pull/2615))

### Changed
- Changed the structure `IoVec` in `::nix::sys::uio`.
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11 changes: 11 additions & 0 deletions src/sys/socket/sockopt.rs
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Expand Up @@ -1268,6 +1268,17 @@ sockopt_impl!(
libc::SO_EXCLBIND,
bool
);
#[cfg(target_os = "linux")]
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Hi there

However, I'd like advice on how to resolve the latter.

If uClibc has that symbol, you can add it to the libc crate. Otherwise, we need to filter it out:

Suggested change
#[cfg(target_os = "linux")]
#[cfg(all(target_os = "linux", not(target_env = "uclibc")))]

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@b-parikh b-parikh Mar 28, 2025 •
edited
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Added tcp_info to the uClibc symbols in libc: rust-lang/libc@4a34937. It looks like the CI still isn't happy though, do you know if that's because the libc change isn't published to crates.io yet?

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That PR rust-lang/libc#4347 added it to the main branch, Nix uses the libc-0.2 branch, so you need to ask the maintainer to backport it to this branch.

Once the backport PR gets merged, update the Cargo.toml file to use it from git:

nix/Cargo.toml

Line 31 in ea012be

libc = { version = "0.2.171", features = ["extra_traits"] } 

- libc = { version = "0.2.171", features = ["extra_traits"] } 
+ libc = { git = "https://github.com/rust-lang/libc", rev = "the commit includes your libc PR", features = ... }

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Got it, thanks! I'll update this PR when the change is backported.

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I'm a bit confused by this comment. The commit was backported to the 0.2 branch: rust-lang/libc@5a1f5f2. Why would pinning the version of the crate in the nix Cargo.toml file be the correct approach? I don't think that should get committed, right?

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Emm, I don't think I understand what you mean, could you please elaborate a bit?

#[cfg(feature = "net")]
sockopt_impl!(
#[cfg_attr(docsrs, doc(cfg(feature = "net")))]
/// Get tcp_info structure.
TcpInfo,
GetOnly,
libc::SOL_TCP,
libc::TCP_INFO,
libc::tcp_info
);

#[allow(missing_docs)]
// Not documented by Linux!
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17 changes: 17 additions & 0 deletions test/sys/test_sockopt.rs
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Expand Up @@ -568,6 +568,23 @@ fn test_ipv6_tclass() {
assert_eq!(getsockopt(&fd, sockopt::Ipv6TClass).unwrap(), class);
}

#[test]
#[cfg(target_os = "linux")]
fn test_tcp_info() {
let fd = socket(
AddressFamily::Inet6,
SockType::Stream,
SockFlag::empty(),
SockProtocol::Tcp,
)
.unwrap();
let tcp_info = getsockopt(&fd, sockopt::TcpInfo).unwrap();
// Silly assert for the sake of having one in the test.
// There should be no retransmits because nothing is sent through the
// socket in the first place.
assert_eq!(tcp_info.tcpi_retransmits, 0);
}

#[test]
#[cfg(target_os = "freebsd")]
fn test_receive_timestamp() {
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