Add peer_addr function to UdpSocket

[LinusU]

Fixes #59104

This is my first pull request to Rust, so opening early for some feedback.

My biggest question is: where do I add tests?

Any comments very much appreciated!

[rust-highfive]

Thanks for the pull request, and welcome! The Rust team is excited to review your changes, and you should hear from @kennytm (or someone else) soon.

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[kennytm]

r=me after docs change.

[rust-highfive]

The job x86_64-gnu-llvm-6.0 of your PR failed on Travis (raw log). Through arcane magic we have determined that the following fragments from the build log may contain information about the problem.

Click to expand the log.

travis_time:end:01aba4ae:start=1552389707315671630,finish=1552389783287767364,duration=75972095734
$ git checkout -qf FETCH_HEAD
travis_fold:end:git.checkout

Encrypted environment variables have been removed for security reasons.
See https://docs.travis-ci.com/user/pull-requests/#pull-requests-and-security-restrictions
$ export SCCACHE_BUCKET=rust-lang-ci-sccache2
$ export SCCACHE_REGION=us-west-1
$ export GCP_CACHE_BUCKET=rust-lang-ci-cache
Setting environment variables from .travis.yml
---
travis_time:start:test_debuginfo
Check compiletest suite=debuginfo mode=debuginfo-both (x86_64-unknown-linux-gnu -> x86_64-unknown-linux-gnu)
[01:25:43] 
[01:25:43] running 120 tests
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[01:26:16] .i......iii.i.....ii
[01:26:16] 
[01:26:16]  finished in 33.806
[01:26:16] travis_fold:end:test_debuginfo

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[01:47:43] failures:
[01:47:43] 
[01:47:43] 
[01:47:43] ---- net/udp.rs - net::udp::UdpSocket::peer_addr (line 198) stdout ----
[01:47:43] error: unused imports: `Ipv4Addr`, `SocketAddrV4`, `SocketAddr`
[01:47:43]  --> net/udp.rs:199:16
[01:47:43]   |
[01:47:43] 4 | use std::net::{Ipv4Addr, SocketAddr, SocketAddrV4, UdpSocket};
[01:47:43]   |
[01:47:43] note: lint level defined here
[01:47:43]  --> net/udp.rs:196:9
[01:47:43]   |
[01:47:43]   |
[01:47:43] 1 | #![deny(warnings)]
[01:47:43]   |         ^^^^^^^^
[01:47:43]   = note: #[deny(unused_imports)] implied by #[deny(warnings)]
[01:47:43] 
[01:47:43] error[E0658]: use of unstable library feature 'udp_peer_addr' (see issue #59127)
[01:47:43]  --> net/udp.rs:202:19
[01:47:43]   |
[01:47:43] 7 | assert_eq!(socket.peer_addr().unwrap_err().kind(),
[01:47:43]   |
[01:47:43]   |
[01:47:43]   = help: add #![feature(udp_peer_addr)] to the crate attributes to enable
[01:47:43] error: aborting due to 2 previous errors
[01:47:43] 
[01:47:43] For more information about this error, try `rustc --explain E0658`.
[01:47:43] thread 'net/udp.rs - net::udp::UdpSocket::peer_addr (line 198)' panicked at 'couldn't compile the test', src/librustdoc/test.rs:310:13
[01:47:43] thread 'net/udp.rs - net::udp::UdpSocket::peer_addr (line 198)' panicked at 'couldn't compile the test', src/librustdoc/test.rs:310:13
[01:47:43] note: Run with `RUST_BACKTRACE=1` environment variable to display a backtrace.
[01:47:43] 
[01:47:43] ---- net/udp.rs - net::udp::UdpSocket::peer_addr (line 189) stdout ----
[01:47:43] error[E0658]: use of unstable library feature 'udp_peer_addr' (see issue #59127)
[01:47:43]  --> net/udp.rs:194:19
[01:47:43]   |
[01:47:43] 8 | assert_eq!(socket.peer_addr().unwrap(),
[01:47:43]   |
[01:47:43]   |
[01:47:43]   = help: add #![feature(udp_peer_addr)] to the crate attributes to enable
[01:47:43] error: aborting due to previous error
[01:47:43] 
[01:47:43] For more information about this error, try `rustc --explain E0658`.
[01:47:43] thread 'net/udp.rs - net::udp::UdpSocket::peer_addr (line 189)' panicked at 'couldn't compile the test', src/librustdoc/test.rs:310:13
---
[01:47:43] 
[01:47:43] error: test failed, to rerun pass '--doc'
[01:47:43] 
[01:47:43] 
[01:47:43] command did not execute successfully: "/checkout/obj/build/x86_64-unknown-linux-gnu/stage0/bin/cargo" "test" "--target" "x86_64-unknown-linux-gnu" "-j" "4" "--release" "--locked" "--color" "always" "--features" "panic-unwind backtrace" "--manifest-path" "/checkout/src/libstd/Cargo.toml" "-p" "std" "--" "--quiet"
[01:47:43] 
[01:47:43] 
[01:47:43] failed to run: /checkout/obj/build/bootstrap/debug/bootstrap test
[01:47:43] Build completed unsuccessfully in 0:35:34
[01:47:43] Build completed unsuccessfully in 0:35:34
[01:47:43] make: *** [check] Error 1
[01:47:43] Makefile:48: recipe for target 'check' failed
The command "stamp sh -x -c "$RUN_SCRIPT"" exited with 2.
travis_time:start:01f13820
$ date && (curl -fs --head https://google.com | grep ^Date: | sed 's/Date: //g' || true)
Tue Mar 12 13:10:57 UTC 2019
---
travis_time:end:0029d224:start=1552396259325954327,finish=1552396259331071461,duration=5117134
travis_fold:end:after_failure.3
travis_fold:start:after_failure.4
travis_time:start:00e3cebc
$ ln -s . checkout && for CORE in obj/cores/core.*; do EXE=$(echo $CORE | sed 's|obj/cores/core\.[0-9]*\.!checkout!\(.*\)|\1|;y|!|/|'); if [ -f "$EXE" ]; then printf travis_fold":start:crashlog\n\033[31;1m%s\033[0m\n" "$CORE"; gdb --batch -q -c "$CORE" "$EXE" -iex 'set auto-load off' -iex 'dir src/' -iex 'set sysroot .' -ex bt -ex q; echo travis_fold":"end:crashlog; fi; done || true
travis_fold:end:after_failure.4
travis_fold:start:after_failure.5
travis_time:start:18e4b66c
travis_time:start:18e4b66c
$ cat ./obj/build/x86_64-unknown-linux-gnu/native/asan/build/lib/asan/clang_rt.asan-dynamic-i386.vers || true
cat: ./obj/build/x86_64-unknown-linux-gnu/native/asan/build/lib/asan/clang_rt.asan-dynamic-i386.vers: No such file or directory
travis_fold:end:after_failure.5
travis_fold:start:after_failure.6
travis_time:start:2cb01576
$ dmesg | grep -i kill

I'm a bot! I can only do what humans tell me to, so if this was not helpful or you have suggestions for improvements, please ping or otherwise contact @TimNN. (Feature Requests)

[jethrogb]

where do I add tests?

At the bottom of src/libstd/net/udp.rs. Use the each_ip function to get IPs you can use for bind/connect.

[LinusU]

Great, thanks!

[LinusU]

Just pushed with added tests, passes locally 🐎

[LinusU]

@kennytm, @jethrogb I think that everything should be good to go now 👍 🚀

Thanks a ton for the help ❤️

[kennytm]

Thanks!

@bors r+

[bors]

📌 Commit ca32fe4 has been approved by kennytm

[kennytm]

@bors r-

Failed in #59207, please implement the new function on wasm as well (and probably SGX too)

[LinusU]

@kennytm should I rebase on the latest master as well? ☺️

[LinusU]

@kennytm Rebased on master, and added the missing implementations. I've searched thru and every impl UdpSocket should now have a corresponding peer_addr implementation ✅

[kennytm]

Thanks again!

@bors r+

[bors]

📌 Commit 81d5fb5 has been approved by kennytm

[LinusU]

Hooray 🎉