Add a fuzzing host

[kevin-montrose]

Makes some small changes to Garnet, and adds a new executable project for fuzzing purposes.

For MS employees, the intended fuzzer is OneFuzz which is (again) an internal tool.

However, this change should enable integration with any fuzzer and for non-MS employees to reproduce reports generated via OneFuzz.

---

For Garnet.fuzz, options are:

  -t, --fuzz-target        Required. Class name to run fuzz input against. Valid
                           values: RespCommandParsing, LuaScriptCompilation,
                           GarnetEndToEnd

  -f, --input-file         (Group: input) Read fuzz input from given file.

  -d, --input-directory    (Group: input) Read fuzz inputs from files in given
                           directory.

  -i, --stdin              (Group: input) Read fuzz input from standard input.

  -c, --run-count          Number of times to run fuzzer for input (default=1)

  -q, --quiet              Suppress output.

  --help                   Display this help screen.

  --version                Display version information.

For the three initial targets:

• RespCommandParsing focuses on RespServerSession.ParseCommand
• LuaScriptCompilation focuses on LuaRunner.CompileForRunner and LuaRunner.RunForRunner
• GarnetEndToEnd shoves commands at EmbeddedRespServer, and has some logic to nudge the fuzzer in the direction of RESP requests

---

Any arbitrary fuzzer can run using either standard input or files. OneFuzz would be invoked like onefuzz template libfuzzer dotnet Garnet.fuzz Garnet.fuzz.dll <version> default bin\Release\net8.0 bin\Release\net8.0\Garnet.fuzz.dll Garnet.fuzz.Targets.<target> Fuzz.

Reproducing reports would use either --input-file or --input-directory, depending on how they are provided. --run-count is intended for cases where crashes do not reproduce on every invocation.

[Copilot]

Copilot reviewed 13 out of 15 changed files in this pull request and generated no comments.

Files not reviewed (2)

• Garnet.sln: Language not supported
• test/Garnet.fuzz/Garnet.fuzz.csproj: Language not supported

Comments suppressed due to low confidence (2)

libs/server/Auth/GarnetNoAuthAuthenticator.cs:9

• [nitpick] Changing the access modifier to public may expose the no-authenticator functionality more broadly than intended; please confirm if this is deliberate or if it should remain internal.

public class GarnetNoAuthAuthenticator : IGarnetAuthenticator

libs/server/Resp/Parser/RespCommand.cs:2640

• Ensure that assigning the pointer from the input buffer does not lead to unsafe memory access outside the intended bounds; consider adding additional validation or a safer abstraction around pointer manipulation.

recvBufferPtr = (byte*)Unsafe.AsPointer(ref MemoryMarshal.GetReference(buffer));