sproto 0.1.0

Rust client for the Synology Drive sync protocol
Documentation 
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use crate::pstream::PObject;

#[derive(Debug, thiserror::Error)]
pub enum Error {
	/// I/O error
	#[error("I/O error: {0}")]
	Io(#[from] std::io::Error),

	/// TLS error
	#[error("TLS error: {0}")]
	Tls(#[from] rustls::Error),

	/// Protocol error: bad magic
	#[error("Protocol error: bad magic")]
	BadMagic,

	/// Protocol error: version mismatch (expected 70-79)
	#[error("Protocol error: version mismatch (got {got}, expected 70-79)")]
	VersionMismatch { got: u8 },

	/// Server error
	#[error("Server error {code:#06x}: {reason}")]
	Server { code: u32, reason: String },

	/// `PStream` decode error
	#[error("PStream decode error: {0}")]
	Decode(String),

	/// Session expired or invalid
	#[error("Session expired or invalid")]
	SessionInvalid,

	/// Connection closed
	#[error("Connection closed")]
	ConnectionClosed,

	/// Invalid configuration
	#[error("invalid configuration: {0}")]
	InvalidConfig(String),

	/// Server build too old for requested operation
	#[error("server build {build} is too old (need {min_build}+): {reason}")]
	UnsupportedServer {
		build: u64,
		min_build: u64,
		reason: String,
	},
}

/// The result type used throughout the library.
pub type Result<T> = std::result::Result<T, Error>;

/// Inspect a response `PObject` for an `"error"` field.
/// Maps session error codes (0x4001-0x4003) to `SessionInvalid`,
/// all other non-null errors to `Error::Server`.
pub fn check_server_error(obj: &PObject) -> Result<()> {
	let Some(err) = obj.get("error") else {
		return Ok(());
	};

	if matches!(err, PObject::Null) {
		return Ok(());
	}

	#[allow(
		clippy::cast_possible_truncation,
		reason = "server error codes are small integers, always fit in u32"
	)]
	let code = err.get("code").and_then(PObject::as_int).unwrap_or(0) as u32;
	let reason = err
		.get("reason")
		.and_then(|v| v.as_str())
		.unwrap_or("unknown")
		.to_string();

	if (0x4001..=0x4003).contains(&code) {
		return Err(Error::SessionInvalid);
	}

	Err(Error::Server { code, reason })
}

#[cfg(test)]
mod tests {
	use super::*;

	#[test]
	fn no_error_field() {
		let obj = pmap! { "type" => "response" };
		assert!(check_server_error(&obj).is_ok());
	}

	#[test]
	fn null_error() {
		let obj = pmap! { "error" => PObject::Null };
		assert!(check_server_error(&obj).is_ok());
	}

	#[test]
	fn session_invalid_errors() {
		for code in [0x4001u64, 0x4002, 0x4003] {
			let obj = pmap! {
				"error" => pmap! {
					"code" => code,
					"reason" => "session gone",
				},
			};
			let err = check_server_error(&obj).unwrap_err();
			assert!(
				matches!(err, Error::SessionInvalid),
				"code {code:#x} should be SessionInvalid"
			);
		}
	}

	#[test]
	fn server_error() {
		let obj = pmap! {
			"error" => pmap! {
				"code" => 0x3002u64,
				"reason" => "Invalid view ID",
			},
		};
		let err = check_server_error(&obj).unwrap_err();
		match err {
			Error::Server { code, reason } => {
				assert_eq!(code, 0x3002);
				assert_eq!(reason, "Invalid view ID");
			},
			_ => panic!("expected Error::Server, got {err:?}"),
		}
	}

	#[test]
	fn error_missing_fields() {
		// Error object with no code/reason — should default gracefully
		let obj = pmap! { "error" => pmap! {} };
		let err = check_server_error(&obj).unwrap_err();
		match err {
			Error::Server { code, reason } => {
				assert_eq!(code, 0);
				assert_eq!(reason, "unknown");
			},
			_ => panic!("expected Error::Server, got {err:?}"),
		}
	}
}