fix: validate CAPABILITY arguments (closes #260)

[Deepak8858]

RFC 3501 specifies that the CAPABILITY command takes no arguments. This PR adds validation to return BAD if arguments are provided, ensuring better compliance with the IMAP protocol.

Fixes #260

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❌ Deepak Singh
❌ Adityasingh-upkgs

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[gemini-code-assist]

Code Review

This pull request updates the HandleCapability function to enforce RFC 3501 compliance by ensuring no arguments are passed to the command. The function signature now includes the command parts, and all references in the codebase and tests have been updated. Feedback identifies a critical syntax error in capability_test.go that causes a compilation failure and suggests adding a test case to verify the new validation logic.

[gemini-code-assist]

This line appears to have a copy-paste error that will cause a compilation failure. The arguments to fmt.Sprintf are incorrect, and the arguments to HandleCapability are misplaced.

Suggested change

	srv.HandleCapability(conn, fmt.Sprintf("STATE%d", []string{fmt.Sprintf("STATE%d", "CAPABILITY"}, i), state)
	srv.HandleCapability(conn, fmt.Sprintf("STATE%d", i), []string{fmt.Sprintf("STATE%d", i), "CAPABILITY"}, state)

[gemini-code-assist]

This argument validation is a good addition for RFC compliance. To ensure it works as expected and prevent future regressions, it would be beneficial to add a test case for this failure scenario.

You could add the following sub-test to TestCapabilityCommand_EdgeCases in internal/server/auth/capability_test.go:

t.Run("WithArguments", func(t *testing.T) {
	srv := server.SetupTestServerSimple(t)
	conn := server.NewMockConn()
	state := &models.ClientState{Authenticated: false}

	tag := "ARGTEST"
	parts := []string{tag, "CAPABILITY", "some_arg"}
	srv.HandleCapability(conn, tag, parts, state)

	response := conn.GetWrittenData()
	expected := fmt.Sprintf("%s BAD CAPABILITY takes no arguments\\r\\n", tag)
	if response != expected {
		t.Errorf("Expected response '%s', got '%s'", expected, response)
	}
})

[maneeshaxyz]

Hi @Deepak8858, thank you for wanting to contribute to the Raven codebase. We ask all our contributors to sign our CLA. You can do so by clicking the link left by the CLA assistant. Once you have done so, please fix the issues picked up by the ci and the merge conflicts. Feel free to tag me and @Aravinda-HWK, once you are done and we will review it.

Thank you for your contribution.