Neqo, an Implementation of QUIC written in Rust

To run test HTTP/3 programs (neqo-client and neqo-server):

• cargo build
• ./target/debug/neqo-server '[::]:12345' --db ./test-fixture/db
• ./target/debug/neqo-client http://127.0.0.1:12345/

If a "Failure to load dynamic library" error happens at runtime, do

export LD_LIBRARY_PATH="$(dirname "$(find . -name libssl3.so -print | head -1)")"

On a macOS, do

export DYLD_LIBRARY_PATH="$(dirname "$(find . -name libssl3.dylib -print | head -1)")"

Faster Builds with Separate NSS/NSPR

You can clone NSS (https://hg.mozilla.org/projects/nss) and NSPR (https://hg.mozilla.org/projects/nspr) into the same directory and export an environment variable called NSS_DIR pointing to NSS. This causes the build to use the existing NSS checkout. However, in order to run anything that depends on NSS, you need to set $\[DY]LD\_LIBRARY\_PATH to point to $NSS_DIR/../dist/Debug/lib.

Note: If you did not compile NSS separately, you need to have mercurial (hg), installed. NSS builds require gyp, and ninja (or ninja-build) to be present also.

Debugging Neqo

QUIC Logging

Enable QLOG with:

$ mkdir "$logdir"
$ ./target/debug/neqo-server '[::]:12345' --db ./test-fixture/db --qlog-dir "$logdir"
$ ./target/debug/neqo-client 'https://[::]:12345/' --qlog-dir "$logdir"

You may use https://qvis.quictools.info/ by uploading the QLOG files and visualize the flows.

Using SSLKEYLOGFILE to decrypt Wireshark logs

Info here

TODO: What is the minimum Wireshark version needed? TODO: Above link may be incorrect, protocol now called TLS instead of SSL?

Using RUST_LOG effectively

As documented in the env_logger documentation, the RUST_LOG environment variable can be used to selectively enable log messages from Rust code. This works for Neqo's cmdline tools, as well as for when Neqo is incorporated into Gecko, although Gecko needs to be built in debug mode.

Some examples:

1. RUST_LOG=neqo_transport::dump ./mach run lists sent and received QUIC packets and their frames' contents only.
2. RUST_LOG=neqo_transport=debug,neqo_http3=trace,info ./mach run sets a 'debug' log level for transport, 'trace' level for http3, and 'info' log level for all other Rust crates, both Neqo and others used by Gecko.
3. RUST_LOG=neqo=trace,error ./mach run sets trace level for all modules starting with "neqo", and sets error as minimum log level for other unrelated Rust log messages.

Trying In-development Neqo code in Gecko

In a checked-out copy of Gecko source, set [patches.*] values for the four Neqo crates to local versions in the root Cargo.toml. For example, if Neqo was checked out to /home/alice/git/neqo, add the following lines to the root Cargo.toml.

[patch."https://github.com/mozilla/neqo"]
neqo-http3 = { path = "/home/alice/git/neqo/neqo-http3" }
neqo-transport = { path = "/home/alice/git/neqo/neqo-transport" }
neqo-common = { path = "/home/alice/git/neqo/neqo-common" }
neqo-qpack = { path = "/home/alice/git/neqo/neqo-qpack" }
neqo-crypto = { path = "/home/alice/git/neqo/neqo-crypto" }

Then run the following:

./mach vendor rust

Compile Gecko as usual with ./mach build.

Note: Using newer Neqo code with Gecko may also require changes (likely to neqo_glue) if something has changed.