Merge pull request #168 from WiredSound/master

Create specific error types for protocol, URL, and capacity errors

CHANGELOG.md

@@ -1,3 +1,8 @@
+# 0.13.0
+
+- Add `CapacityError`, `UrlError`, and `ProtocolError` types to represent the different types of capacity, URL, and protocol errors respectively.
+- Modify variants `Error::Capacity`, `Error::Url`, and `Error::Protocol` to hold the above errors types instead of string error messages.
+
 # 0.12.0
 
 - Add facilities to allow clients to follow HTTP 3XX redirects.

Cargo.toml

@@ -9,7 +9,7 @@ readme = "README.md"
 homepage = "https://github.com/snapview/tungstenite-rs"
 documentation = "https://docs.rs/tungstenite/0.12.0"
 repository = "https://github.com/snapview/tungstenite-rs"
-version = "0.12.0"
+version = "0.13.0"
 edition = "2018"
 
 [features]
@@ -29,6 +29,7 @@ rand = "0.8.0"
 sha-1 = "0.9"
 url = "2.1.0"
 utf-8 = "0.7.5"
+thiserror = "1.0.23"
 
 [dependencies.native-tls]
 optional = true

README.md

@@ -62,7 +62,7 @@ Testing
 -------
 
 Tungstenite is thoroughly tested and passes the [Autobahn Test Suite](https://crossbar.io/autobahn/) for
-WebSockets. It is also covered by internal unit tests as good as possible.
+WebSockets. It is also covered by internal unit tests as well as possible.
 
 Contributing
 ------------

src/client.rs

@@ -52,7 +52,7 @@ mod encryption {
     use std::net::TcpStream;
 
     use crate::{
-        error::{Error, Result},
+        error::{Error, Result, UrlError},
         stream::Mode,
     };
 
@@ -62,7 +62,7 @@ mod encryption {
     pub fn wrap_stream(stream: TcpStream, _domain: &str, mode: Mode) -> Result<AutoStream> {
         match mode {
             Mode::Plain => Ok(stream),
-            Mode::Tls => Err(Error::Url("TLS support not compiled in.".into())),
+            Mode::Tls => Err(Error::Url(UrlError::TlsFeatureNotEnabled)),
         }
     }
 }
@@ -71,7 +71,7 @@ use self::encryption::wrap_stream;
 pub use self::encryption::AutoStream;
 
 use crate::{
-    error::{Error, Result},
+    error::{Error, Result, UrlError},
     handshake::{client::ClientHandshake, HandshakeError},
     protocol::WebSocket,
     stream::{Mode, NoDelay},
@@ -103,8 +103,7 @@ pub fn connect_with_config<Req: IntoClientRequest>(
     ) -> Result<(WebSocket<AutoStream>, Response)> {
         let uri = request.uri();
         let mode = uri_mode(uri)?;
-        let host =
+        let host = request.uri().host().ok_or(Error::Url(UrlError::NoHostName))?;
-            request.uri().host().ok_or_else(|| Error::Url("No host name in the URL".into()))?;
         let port = uri.port_u16().unwrap_or(match mode {
             Mode::Plain => 80,
             Mode::Tls => 443,
@@ -166,7 +165,7 @@ pub fn connect<Req: IntoClientRequest>(request: Req) -> Result<(WebSocket<AutoSt
 }
 
 fn connect_to_some(addrs: &[SocketAddr], uri: &Uri, mode: Mode) -> Result<AutoStream> {
-    let domain = uri.host().ok_or_else(|| Error::Url("No host name in the URL".into()))?;
+    let domain = uri.host().ok_or(Error::Url(UrlError::NoHostName))?;
     for addr in addrs {
         debug!("Trying to contact {} at {}...", uri, addr);
         if let Ok(raw_stream) = TcpStream::connect(addr) {
@@ -175,7 +174,7 @@ fn connect_to_some(addrs: &[SocketAddr], uri: &Uri, mode: Mode) -> Result<AutoSt
             }
         }
     }
-    Err(Error::Url(format!("Unable to connect to {}", uri).into()))
+    Err(Error::Url(UrlError::UnableToConnect(uri.to_string())))
 }
 
 /// Get the mode of the given URL.
@@ -186,7 +185,7 @@ pub fn uri_mode(uri: &Uri) -> Result<Mode> {
     match uri.scheme_str() {
         Some("ws") => Ok(Mode::Plain),
         Some("wss") => Ok(Mode::Tls),
-        _ => Err(Error::Url("URL scheme not supported".into())),
+        _ => Err(Error::Url(UrlError::UnsupportedUrlScheme)),
     }
 }
 

src/error.rs

@@ -1,9 +1,10 @@
 //! Error handling.
 
-use std::{borrow::Cow, error::Error as ErrorTrait, fmt, io, result, str, string};
+use std::{io, result, str, string};
 
-use crate::protocol::Message;
+use crate::protocol::{frame::coding::Data, Message};
 use http::Response;
+use thiserror::Error;
 
 #[cfg(feature = "tls")]
 pub mod tls {
@@ -14,8 +15,8 @@ pub mod tls {
 /// Result type of all Tungstenite library calls.
 pub type Result<T> = result::Result<T, Error>;
 
-/// Possible WebSocket errors
+/// Possible WebSocket errors.
-#[derive(Debug)]
+#[derive(Error, Debug)]
 pub enum Error {
     /// WebSocket connection closed normally. This informs you of the close.
     /// It's not an error as such and nothing wrong happened.
@@ -28,6 +29,7 @@ pub enum Error {
     ///
     /// Receiving this error means that the WebSocket object is not usable anymore and the
     /// only meaningful action with it is dropping it.
+    #[error("Connection closed normally")]
     ConnectionClosed,
     /// Trying to work with already closed connection.
     ///
@@ -36,56 +38,39 @@ pub enum Error {
     /// As opposed to `ConnectionClosed`, this indicates your code tries to operate on the
     /// connection when it really shouldn't anymore, so this really indicates a programmer
     /// error on your part.
+    #[error("Trying to work with closed connection")]
     AlreadyClosed,
     /// Input-output error. Apart from WouldBlock, these are generally errors with the
     /// underlying connection and you should probably consider them fatal.
-    Io(io::Error),
+    #[error("IO error: {0}")]
+    Io(#[from] io::Error),
+    /// TLS error.
     #[cfg(feature = "tls")]
-    /// TLS error
+    #[error("TLS error: {0}")]
-    Tls(tls::Error),
+    Tls(#[from] tls::Error),
     /// - When reading: buffer capacity exhausted.
     /// - When writing: your message is bigger than the configured max message size
     ///   (64MB by default).
-    Capacity(Cow<'static, str>),
+    #[error("Space limit exceeded: {0}")]
+    Capacity(CapacityError),
     /// Protocol violation.
-    Protocol(Cow<'static, str>),
+    #[error("WebSocket protocol error: {0}")]
+    Protocol(ProtocolError),
     /// Message send queue full.
+    #[error("Send queue is full")]
     SendQueueFull(Message),
-    /// UTF coding error
+    /// UTF coding error.
+    #[error("UTF-8 encoding error")]
     Utf8,
     /// Invalid URL.
-    Url(Cow<'static, str>),
+    #[error("URL error: {0}")]
+    Url(UrlError),
     /// HTTP error.
+    #[error("HTTP error: {}", .0.status())]
     Http(Response<Option<String>>),
     /// HTTP format error.
-    HttpFormat(http::Error),
+    #[error("HTTP format error: {0}")]
-}
+    HttpFormat(#[from] http::Error),
-
-impl fmt::Display for Error {
-    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
-        match *self {
-            Error::ConnectionClosed => write!(f, "Connection closed normally"),
-            Error::AlreadyClosed => write!(f, "Trying to work with closed connection"),
-            Error::Io(ref err) => write!(f, "IO error: {}", err),
-            #[cfg(feature = "tls")]
-            Error::Tls(ref err) => write!(f, "TLS error: {}", err),
-            Error::Capacity(ref msg) => write!(f, "Space limit exceeded: {}", msg),
-            Error::Protocol(ref msg) => write!(f, "WebSocket protocol error: {}", msg),
-            Error::SendQueueFull(_) => write!(f, "Send queue is full"),
-            Error::Utf8 => write!(f, "UTF-8 encoding error"),
-            Error::Url(ref msg) => write!(f, "URL error: {}", msg),
-            Error::Http(ref code) => write!(f, "HTTP error: {}", code.status()),
-            Error::HttpFormat(ref err) => write!(f, "HTTP format error: {}", err),
-        }
-    }
-}
-
-impl ErrorTrait for Error {}
-
-impl From<io::Error> for Error {
-    fn from(err: io::Error) -> Self {
-        Error::Io(err)
-    }
 }
 
 impl From<str::Utf8Error> for Error {
@@ -130,24 +115,136 @@ impl From<http::status::InvalidStatusCode> for Error {
     }
 }
 
-impl From<http::Error> for Error {
-    fn from(err: http::Error) -> Self {
-        Error::HttpFormat(err)
-    }
-}
-
-#[cfg(feature = "tls")]
-impl From<tls::Error> for Error {
-    fn from(err: tls::Error) -> Self {
-        Error::Tls(err)
-    }
-}
-
 impl From<httparse::Error> for Error {
     fn from(err: httparse::Error) -> Self {
         match err {
-            httparse::Error::TooManyHeaders => Error::Capacity("Too many headers".into()),
+            httparse::Error::TooManyHeaders => Error::Capacity(CapacityError::TooManyHeaders),
-            e => Error::Protocol(e.to_string().into()),
+            e => Error::Protocol(ProtocolError::HttparseError(e)),
         }
     }
 }
+
+/// Indicates the specific type/cause of a capacity error.
+#[derive(Error, Debug, PartialEq, Eq, Clone, Copy)]
+pub enum CapacityError {
+    /// Too many headers provided (see [`httparse::Error::TooManyHeaders`]).
+    #[error("Too many headers")]
+    TooManyHeaders,
+    /// Received header is too long.
+    #[error("Header too long")]
+    HeaderTooLong,
+    /// Message is bigger than the maximum allowed size.
+    #[error("Message too long: {size} > {max_size}")]
+    MessageTooLong {
+        /// The size of the message.
+        size: usize,
+        /// The maximum allowed message size.
+        max_size: usize,
+    },
+    /// TCP buffer is full.
+    #[error("Incoming TCP buffer is full")]
+    TcpBufferFull,
+}
+
+/// Indicates the specific type/cause of a protocol error.
+#[derive(Error, Debug, PartialEq, Eq, Clone, Copy)]
+pub enum ProtocolError {
+    /// Use of the wrong HTTP method (the WebSocket protocol requires the GET method be used).
+    #[error("Unsupported HTTP method used - only GET is allowed")]
+    WrongHttpMethod,
+    /// Wrong HTTP version used (the WebSocket protocol requires version 1.1 or higher).
+    #[error("HTTP version must be 1.1 or higher")]
+    WrongHttpVersion,
+    /// Missing `Connection: upgrade` HTTP header.
+    #[error("No \"Connection: upgrade\" header")]
+    MissingConnectionUpgradeHeader,
+    /// Missing `Upgrade: websocket` HTTP header.
+    #[error("No \"Upgrade: websocket\" header")]
+    MissingUpgradeWebSocketHeader,
+    /// Missing `Sec-WebSocket-Version: 13` HTTP header.
+    #[error("No \"Sec-WebSocket-Version: 13\" header")]
+    MissingSecWebSocketVersionHeader,
+    /// Missing `Sec-WebSocket-Key` HTTP header.
+    #[error("No \"Sec-WebSocket-Key\" header")]
+    MissingSecWebSocketKey,
+    /// The `Sec-WebSocket-Accept` header is either not present or does not specify the correct key value.
+    #[error("Key mismatch in \"Sec-WebSocket-Accept\" header")]
+    SecWebSocketAcceptKeyMismatch,
+    /// Garbage data encountered after client request.
+    #[error("Junk after client request")]
+    JunkAfterRequest,
+    /// Custom responses must be unsuccessful.
+    #[error("Custom response must not be successful")]
+    CustomResponseSuccessful,
+    /// No more data while still performing handshake.
+    #[error("Handshake not finished")]
+    HandshakeIncomplete,
+    /// Wrapper around a [`httparse::Error`] value.
+    #[error("httparse error: {0}")]
+    HttparseError(#[from] httparse::Error),
+    /// Not allowed to send after having sent a closing frame.
+    #[error("Sending after closing is not allowed")]
+    SendAfterClosing,
+    /// Remote sent data after sending a closing frame.
+    #[error("Remote sent after having closed")]
+    ReceivedAfterClosing,
+    /// Reserved bits in frame header are non-zero.
+    #[error("Reserved bits are non-zero")]
+    NonZeroReservedBits,
+    /// The server must close the connection when an unmasked frame is received.
+    #[error("Received an unmasked frame from client")]
+    UnmaskedFrameFromClient,
+    /// The client must close the connection when a masked frame is received.
+    #[error("Received a masked frame from server")]
+    MaskedFrameFromServer,
+    /// Control frames must not be fragmented.
+    #[error("Fragmented control frame")]
+    FragmentedControlFrame,
+    /// Control frames must have a payload of 125 bytes or less.
+    #[error("Control frame too big (payload must be 125 bytes or less)")]
+    ControlFrameTooBig,
+    /// Type of control frame not recognised.
+    #[error("Unknown control frame type: {0}")]
+    UnknownControlFrameType(u8),
+    /// Type of data frame not recognised.
+    #[error("Unknown data frame type: {0}")]
+    UnknownDataFrameType(u8),
+    /// Received a continue frame despite there being nothing to continue.
+    #[error("Continue frame but nothing to continue")]
+    UnexpectedContinueFrame,
+    /// Received data while waiting for more fragments.
+    #[error("While waiting for more fragments received: {0}")]
+    ExpectedFragment(Data),
+    /// Connection closed without performing the closing handshake.
+    #[error("Connection reset without closing handshake")]
+    ResetWithoutClosingHandshake,
+    /// Encountered an invalid opcode.
+    #[error("Encountered invalid opcode: {0}")]
+    InvalidOpcode(u8),
+    /// The payload for the closing frame is invalid.
+    #[error("Invalid close sequence")]
+    InvalidCloseSequence,
+}
+
+/// Indicates the specific type/cause of URL error.
+#[derive(Error, Debug, PartialEq, Eq)]
+pub enum UrlError {
+    /// TLS is used despite not being compiled with the TLS feature enabled.
+    #[error("TLS support not compiled in")]
+    TlsFeatureNotEnabled,
+    /// The URL does not include a host name.
+    #[error("No host name in the URL")]
+    NoHostName,
+    /// Failed to connect with this URL.
+    #[error("Unable to connect to {0}")]
+    UnableToConnect(String),
+    /// Unsupported URL scheme used (only `ws://` or `wss://` may be used).
+    #[error("URL scheme not supported")]
+    UnsupportedUrlScheme,
+    /// The URL host name, though included, is empty.
+    #[error("URL contains empty host name")]
+    EmptyHostName,
+    /// The URL does not include a path/query.
+    #[error("No path/query in URL")]
+    NoPathOrQuery,
+}

src/handshake/client.rs

@@ -16,7 +16,7 @@ use super::{
     HandshakeRole, MidHandshake, ProcessingResult,
 };
 use crate::{
-    error::{Error, Result},
+    error::{Error, ProtocolError, Result, UrlError},
     protocol::{Role, WebSocket, WebSocketConfig},
 };
 
@@ -42,11 +42,11 @@ impl<S: Read + Write> ClientHandshake<S> {
         config: Option<WebSocketConfig>,
     ) -> Result<MidHandshake<Self>> {
         if request.method() != http::Method::GET {
-            return Err(Error::Protocol("Invalid HTTP method, only GET supported".into()));
+            return Err(Error::Protocol(ProtocolError::WrongHttpMethod));
         }
 
         if request.version() < http::Version::HTTP_11 {
-            return Err(Error::Protocol("HTTP version should be 1.1 or higher".into()));
+            return Err(Error::Protocol(ProtocolError::WrongHttpVersion));
         }
 
         // Check the URI scheme: only ws or wss are supported
@@ -97,8 +97,7 @@ fn generate_request(request: Request, key: &str) -> Result<Vec<u8>> {
     let mut req = Vec::new();
     let uri = request.uri();
 
-    let authority =
+    let authority = uri.authority().ok_or(Error::Url(UrlError::NoHostName))?.as_str();
-        uri.authority().ok_or_else(|| Error::Url("No host name in the URL".into()))?.as_str();
     let host = if let Some(idx) = authority.find('@') {
         // handle possible name:password@
         authority.split_at(idx + 1).1
@@ -106,7 +105,7 @@ fn generate_request(request: Request, key: &str) -> Result<Vec<u8>> {
         authority
     };
     if authority.is_empty() {
-        return Err(Error::Url("URL contains empty host name".into()));
+        return Err(Error::Url(UrlError::EmptyHostName));
     }
 
     write!(
@@ -120,8 +119,7 @@ fn generate_request(request: Request, key: &str) -> Result<Vec<u8>> {
          Sec-WebSocket-Key: {key}\r\n",
         version = request.version(),
         host = host,
-        path =
+        path = uri.path_and_query().ok_or(Error::Url(UrlError::NoPathOrQuery))?.as_str(),
-            uri.path_and_query().ok_or_else(|| Error::Url("No path/query in URL".into()))?.as_str(),
         key = key
     )
     .unwrap();
@@ -165,7 +163,7 @@ impl VerifyData {
             .map(|h| h.eq_ignore_ascii_case("websocket"))
             .unwrap_or(false)
         {
-            return Err(Error::Protocol("No \"Upgrade: websocket\" in server reply".into()));
+            return Err(Error::Protocol(ProtocolError::MissingUpgradeWebSocketHeader));
         }
         // 3.  If the response lacks a |Connection| header field or the
         // |Connection| header field doesn't contain a token that is an
@@ -177,14 +175,14 @@ impl VerifyData {
             .map(|h| h.eq_ignore_ascii_case("Upgrade"))
             .unwrap_or(false)
         {
-            return Err(Error::Protocol("No \"Connection: upgrade\" in server reply".into()));
+            return Err(Error::Protocol(ProtocolError::MissingConnectionUpgradeHeader));
         }
         // 4.  If the response lacks a |Sec-WebSocket-Accept| header field or
         // the |Sec-WebSocket-Accept| contains a value other than the
         // base64-encoded SHA-1 of ... the client MUST _Fail the WebSocket
         // Connection_. (RFC 6455)
         if !headers.get("Sec-WebSocket-Accept").map(|h| h == &self.accept_key).unwrap_or(false) {
-            return Err(Error::Protocol("Key mismatch in Sec-WebSocket-Accept".into()));
+            return Err(Error::Protocol(ProtocolError::SecWebSocketAcceptKeyMismatch));
         }
         // 5.  If the response includes a |Sec-WebSocket-Extensions| header
         // field and this header field indicates the use of an extension
@@ -218,7 +216,7 @@ impl TryParse for Response {
 impl<'h, 'b: 'h> FromHttparse<httparse::Response<'h, 'b>> for Response {
     fn from_httparse(raw: httparse::Response<'h, 'b>) -> Result<Self> {
         if raw.version.expect("Bug: no HTTP version") < /*1.*/1 {
-            return Err(Error::Protocol("HTTP version should be 1.1 or higher".into()));
+            return Err(Error::Protocol(ProtocolError::WrongHttpMethod));
         }
 
         let headers = HeaderMap::from_httparse(raw.headers)?;

src/handshake/machine.rs

@@ -3,7 +3,7 @@ use log::*;
 use std::io::{Cursor, Read, Write};
 
 use crate::{
-    error::{Error, Result},
+    error::{CapacityError, Error, ProtocolError, Result},
     util::NonBlockingResult,
 };
 use input_buffer::{InputBuffer, MIN_READ};
@@ -46,11 +46,11 @@ impl<Stream: Read + Write> HandshakeMachine<Stream> {
                 let read = buf
                     .prepare_reserve(MIN_READ)
                     .with_limit(usize::max_value()) // TODO limit size
-                    .map_err(|_| Error::Capacity("Header too long".into()))?
+                    .map_err(|_| Error::Capacity(CapacityError::HeaderTooLong))?
                     .read_from(&mut self.stream)
                     .no_block()?;
                 match read {
-                    Some(0) => Err(Error::Protocol("Handshake not finished".into())),
+                    Some(0) => Err(Error::Protocol(ProtocolError::HandshakeIncomplete)),
                     Some(_) => Ok(if let Some((size, obj)) = Obj::try_parse(Buf::chunk(&buf))? {
                         buf.advance(size);
                         RoundResult::StageFinished(StageResult::DoneReading {

src/handshake/server.rs

@@ -19,7 +19,7 @@ use super::{
     HandshakeRole, MidHandshake, ProcessingResult,
 };
 use crate::{
-    error::{Error, Result},
+    error::{Error, ProtocolError, Result},
     protocol::{Role, WebSocket, WebSocketConfig},
 };
 
@@ -34,11 +34,11 @@ pub type ErrorResponse = HttpResponse<Option<String>>;
 
 fn create_parts<T>(request: &HttpRequest<T>) -> Result<Builder> {
     if request.method() != http::Method::GET {
-        return Err(Error::Protocol("Method is not GET".into()));
+        return Err(Error::Protocol(ProtocolError::WrongHttpMethod));
     }
 
     if request.version() < http::Version::HTTP_11 {
-        return Err(Error::Protocol("HTTP version should be 1.1 or higher".into()));
+        return Err(Error::Protocol(ProtocolError::WrongHttpVersion));
     }
 
     if !request
@@ -48,7 +48,7 @@ fn create_parts<T>(request: &HttpRequest<T>) -> Result<Builder> {
         .map(|h| h.split(|c| c == ' ' || c == ',').any(|p| p.eq_ignore_ascii_case("Upgrade")))
         .unwrap_or(false)
     {
-        return Err(Error::Protocol("No \"Connection: upgrade\" in client request".into()));
+        return Err(Error::Protocol(ProtocolError::MissingConnectionUpgradeHeader));
     }
 
     if !request
@@ -58,17 +58,17 @@ fn create_parts<T>(request: &HttpRequest<T>) -> Result<Builder> {
         .map(|h| h.eq_ignore_ascii_case("websocket"))
         .unwrap_or(false)
     {
-        return Err(Error::Protocol("No \"Upgrade: websocket\" in client request".into()));
+        return Err(Error::Protocol(ProtocolError::MissingUpgradeWebSocketHeader));
     }
 
     if !request.headers().get("Sec-WebSocket-Version").map(|h| h == "13").unwrap_or(false) {
-        return Err(Error::Protocol("No \"Sec-WebSocket-Version: 13\" in client request".into()));
+        return Err(Error::Protocol(ProtocolError::MissingSecWebSocketVersionHeader));
     }
 
     let key = request
         .headers()
         .get("Sec-WebSocket-Key")
-        .ok_or_else(|| Error::Protocol("Missing Sec-WebSocket-Key".into()))?;
+        .ok_or(Error::Protocol(ProtocolError::MissingSecWebSocketKey))?;
 
     let builder = Response::builder()
         .status(StatusCode::SWITCHING_PROTOCOLS)
@@ -125,11 +125,11 @@ impl TryParse for Request {
 impl<'h, 'b: 'h> FromHttparse<httparse::Request<'h, 'b>> for Request {
     fn from_httparse(raw: httparse::Request<'h, 'b>) -> Result<Self> {
         if raw.method.expect("Bug: no method in header") != "GET" {
-            return Err(Error::Protocol("Method is not GET".into()));
+            return Err(Error::Protocol(ProtocolError::WrongHttpMethod));
         }
 
         if raw.version.expect("Bug: no HTTP version") < /*1.*/1 {
-            return Err(Error::Protocol("HTTP version should be 1.1 or higher".into()));
+            return Err(Error::Protocol(ProtocolError::WrongHttpVersion));
         }
 
         let headers = HeaderMap::from_httparse(raw.headers)?;
@@ -237,7 +237,7 @@ impl<S: Read + Write, C: Callback> HandshakeRole for ServerHandshake<S, C> {
         Ok(match finish {
             StageResult::DoneReading { stream, result, tail } => {
                 if !tail.is_empty() {
-                    return Err(Error::Protocol("Junk after client request".into()));
+                    return Err(Error::Protocol(ProtocolError::JunkAfterRequest));
                 }
 
                 let response = create_response(&result)?;
@@ -256,9 +256,7 @@ impl<S: Read + Write, C: Callback> HandshakeRole for ServerHandshake<S, C> {
 
                     Err(resp) => {
                         if resp.status().is_success() {
-                            return Err(Error::Protocol(
+                            return Err(Error::Protocol(ProtocolError::CustomResponseSuccessful));
-                                "Custom response must not be successful".into(),
-                            ));
                         }
 
                         self.error_response = Some(resp);

src/protocol/frame/coding.rs

@@ -143,7 +143,7 @@ pub enum CloseCode {
     Abnormal,
     /// Indicates that an endpoint is terminating the connection
     /// because it has received data within a message that was not
-    /// consistent with the type of the message (e.g., non-UTF-8 [RFC3629]
+    /// consistent with the type of the message (e.g., non-UTF-8 \[RFC3629\]
     /// data within a text message).
     Invalid,
     /// Indicates that an endpoint is terminating the connection

src/protocol/frame/frame.rs

@@ -13,7 +13,7 @@ use super::{
     coding::{CloseCode, Control, Data, OpCode},
     mask::{apply_mask, generate_mask},
 };
-use crate::error::{Error, Result};
+use crate::error::{Error, ProtocolError, Result};
 
 /// A struct representing the close command.
 #[derive(Debug, Clone, Eq, PartialEq)]
@@ -186,9 +186,7 @@ impl FrameHeader {
         // Disallow bad opcode
         match opcode {
             OpCode::Control(Control::Reserved(_)) | OpCode::Data(Data::Reserved(_)) => {
-                return Err(Error::Protocol(
+                return Err(Error::Protocol(ProtocolError::InvalidOpcode(first & 0x0F)))
-                    format!("Encountered invalid opcode: {}", first & 0x0F).into(),
-                ))
             }
             _ => (),
         }
@@ -286,7 +284,7 @@ impl Frame {
     pub(crate) fn into_close(self) -> Result<Option<CloseFrame<'static>>> {
         match self.payload.len() {
             0 => Ok(None),
-            1 => Err(Error::Protocol("Invalid close sequence".into())),
+            1 => Err(Error::Protocol(ProtocolError::InvalidCloseSequence)),
             _ => {
                 let mut data = self.payload;
                 let code = NetworkEndian::read_u16(&data[0..2]).into();

src/protocol/frame/mod.rs

@@ -8,7 +8,7 @@ mod mask;
 
 pub use self::frame::{CloseFrame, Frame, FrameHeader};
 
-use crate::error::{Error, Result};
+use crate::error::{CapacityError, Error, Result};
 use input_buffer::{InputBuffer, MIN_READ};
 use log::*;
 use std::io::{Error as IoError, ErrorKind as IoErrorKind, Read, Write};
@@ -133,9 +133,10 @@ impl FrameCodec {
                     // Enforce frame size limit early and make sure `length`
                     // is not too big (fits into `usize`).
                     if length > max_size as u64 {
-                        return Err(Error::Capacity(
+                        return Err(Error::Capacity(CapacityError::MessageTooLong {
-                            format!("Message length too big: {} > {}", length, max_size).into(),
+                            size: length as usize,
-                        ));
+                            max_size,
+                        }));
                     }
 
                     let input_size = cursor.get_ref().len() as u64 - cursor.position();
@@ -155,7 +156,7 @@ impl FrameCodec {
                 .in_buffer
                 .prepare_reserve(MIN_READ)
                 .with_limit(usize::max_value())
-                .map_err(|_| Error::Capacity("Incoming TCP buffer is full".into()))?
+                .map_err(|_| Error::Capacity(CapacityError::TcpBufferFull))?
                 .read_from(stream)?;
             if size == 0 {
                 trace!("no frame received");
@@ -206,6 +207,8 @@ impl FrameCodec {
 #[cfg(test)]
 mod tests {
 
+    use crate::error::{CapacityError, Error};
+
     use super::{Frame, FrameSocket};
 
     use std::io::Cursor;
@@ -266,9 +269,9 @@ mod tests {
     fn size_limit_hit() {
         let raw = Cursor::new(vec![0x82, 0x07, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07]);
         let mut sock = FrameSocket::new(raw);
-        assert_eq!(
+        assert!(matches!(
-            sock.read_frame(Some(5)).unwrap_err().to_string(),
+            sock.read_frame(Some(5)),
-            "Space limit exceeded: Message length too big: 7 > 5"
+            Err(Error::Capacity(CapacityError::MessageTooLong { size: 7, max_size: 5 }))
-        );
+        ));
     }
 }

src/protocol/message.rs

@@ -6,7 +6,7 @@ use std::{
 };
 
 use super::frame::CloseFrame;
-use crate::error::{Error, Result};
+use crate::error::{CapacityError, Error, Result};
 
 mod string_collect {
     use utf8::DecodeError;
@@ -122,9 +122,10 @@ impl IncompleteMessage {
         let portion_size = tail.as_ref().len();
         // Be careful about integer overflows here.
         if my_size > max_size || portion_size > max_size - my_size {
-            return Err(Error::Capacity(
+            return Err(Error::Capacity(CapacityError::MessageTooLong {
-                format!("Message too big: {} + {} > {}", my_size, portion_size, max_size).into(),
+                size: my_size + portion_size,
-            ));
+                max_size,
+            }));
         }
 
         match self.collector {

src/protocol/mod.rs

@@ -21,7 +21,7 @@ use self::{
     message::{IncompleteMessage, IncompleteMessageType},
 };
 use crate::{
-    error::{Error, Result},
+    error::{Error, ProtocolError, Result},
     util::NonBlockingResult,
 };
 
@@ -331,7 +331,7 @@ impl WebSocketContext {
 
         // Do not write after sending a close frame.
         if !self.state.is_active() {
-            return Err(Error::Protocol("Sending after closing is not allowed".into()));
+            return Err(Error::Protocol(ProtocolError::SendAfterClosing));
         }
 
         if let Some(max_send_queue) = self.config.max_send_queue {
@@ -431,9 +431,7 @@ impl WebSocketContext {
             .check_connection_reset(self.state)?
         {
             if !self.state.can_read() {
-                return Err(Error::Protocol(
+                return Err(Error::Protocol(ProtocolError::ReceivedAfterClosing));
-                    "Remote sent frame after having sent a Close Frame".into(),
-                ));
             }
             // MUST be 0 unless an extension is negotiated that defines meanings
             // for non-zero values.  If a nonzero value is received and none of
@@ -443,7 +441,7 @@ impl WebSocketContext {
             {
                 let hdr = frame.header();
                 if hdr.rsv1 || hdr.rsv2 || hdr.rsv3 {
-                    return Err(Error::Protocol("Reserved bits are non-zero".into()));
+                    return Err(Error::Protocol(ProtocolError::NonZeroReservedBits));
                 }
             }
 
@@ -458,15 +456,13 @@ impl WebSocketContext {
                         // frame that is not masked. (RFC 6455)
                         // The only exception here is if the user explicitly accepts given
                         // stream by setting WebSocketConfig.accept_unmasked_frames to true
-                        return Err(Error::Protocol(
+                        return Err(Error::Protocol(ProtocolError::UnmaskedFrameFromClient));
-                            "Received an unmasked frame from client".into(),
-                        ));
                     }
                 }
                 Role::Client => {
                     if frame.is_masked() {
                         // A client MUST close a connection if it detects a masked frame. (RFC 6455)
-                        return Err(Error::Protocol("Received a masked frame from server".into()));
+                        return Err(Error::Protocol(ProtocolError::MaskedFrameFromServer));
                     }
                 }
             }
@@ -477,14 +473,14 @@ impl WebSocketContext {
                         // All control frames MUST have a payload length of 125 bytes or less
                         // and MUST NOT be fragmented. (RFC 6455)
                         _ if !frame.header().is_final => {
-                            Err(Error::Protocol("Fragmented control frame".into()))
+                            Err(Error::Protocol(ProtocolError::FragmentedControlFrame))
                         }
                         _ if frame.payload().len() > 125 => {
-                            Err(Error::Protocol("Control frame too big".into()))
+                            Err(Error::Protocol(ProtocolError::ControlFrameTooBig))
                         }
                         OpCtl::Close => Ok(self.do_close(frame.into_close()?).map(Message::Close)),
                         OpCtl::Reserved(i) => {
-                            Err(Error::Protocol(format!("Unknown control frame type {}", i).into()))
+                            Err(Error::Protocol(ProtocolError::UnknownControlFrameType(i)))
                         }
                         OpCtl::Ping => {
                             let data = frame.into_data();
@@ -506,7 +502,7 @@ impl WebSocketContext {
                                 msg.extend(frame.into_data(), self.config.max_message_size)?;
                             } else {
                                 return Err(Error::Protocol(
-                                    "Continue frame but nothing to continue".into(),
+                                    ProtocolError::UnexpectedContinueFrame,
                                 ));
                             }
                             if fin {
@@ -515,9 +511,9 @@ impl WebSocketContext {
                                 Ok(None)
                             }
                         }
-                        c if self.incomplete.is_some() => Err(Error::Protocol(
+                        c if self.incomplete.is_some() => {
-                            format!("Received {} while waiting for more fragments", c).into(),
+                            Err(Error::Protocol(ProtocolError::ExpectedFragment(c)))
-                        )),
+                        }
                         OpData::Text | OpData::Binary => {
                             let msg = {
                                 let message_type = match data {
@@ -537,7 +533,7 @@ impl WebSocketContext {
                             }
                         }
                         OpData::Reserved(i) => {
-                            Err(Error::Protocol(format!("Unknown data frame type {}", i).into()))
+                            Err(Error::Protocol(ProtocolError::UnknownDataFrameType(i)))
                         }
                     }
                 }
@@ -548,7 +544,7 @@ impl WebSocketContext {
                 WebSocketState::ClosedByPeer | WebSocketState::CloseAcknowledged => {
                     Err(Error::ConnectionClosed)
                 }
-                _ => Err(Error::Protocol("Connection reset without closing handshake".into())),
+                _ => Err(Error::Protocol(ProtocolError::ResetWithoutClosingHandshake)),
             }
         }
     }
@@ -673,6 +669,7 @@ impl<T> CheckConnectionReset for Result<T> {
 #[cfg(test)]
 mod tests {
     use super::{Message, Role, WebSocket, WebSocketConfig};
+    use crate::error::{CapacityError, Error};
 
     use std::{io, io::Cursor};
 
@@ -715,10 +712,11 @@ mod tests {
         ]);
         let limit = WebSocketConfig { max_message_size: Some(10), ..WebSocketConfig::default() };
         let mut socket = WebSocket::from_raw_socket(WriteMoc(incoming), Role::Client, Some(limit));
-        assert_eq!(
+
-            socket.read_message().unwrap_err().to_string(),
+        assert!(matches!(
-            "Space limit exceeded: Message too big: 7 + 6 > 10"
+            socket.read_message(),
-        );
+            Err(Error::Capacity(CapacityError::MessageTooLong { size: 13, max_size: 10 }))
+        ));
     }
 
     #[test]
@@ -726,9 +724,10 @@ mod tests {
         let incoming = Cursor::new(vec![0x82, 0x03, 0x01, 0x02, 0x03]);
         let limit = WebSocketConfig { max_message_size: Some(2), ..WebSocketConfig::default() };
         let mut socket = WebSocket::from_raw_socket(WriteMoc(incoming), Role::Client, Some(limit));
-        assert_eq!(
+
-            socket.read_message().unwrap_err().to_string(),
+        assert!(matches!(
-            "Space limit exceeded: Message too big: 0 + 3 > 2"
+            socket.read_message(),
-        );
+            Err(Error::Capacity(CapacityError::MessageTooLong { size: 3, max_size: 2 }))
+        ));
     }
 }

tests/no_send_after_close.rs

@@ -8,7 +8,7 @@ use std::{
     time::Duration,
 };
 
-use tungstenite::{accept, connect, Error, Message};
+use tungstenite::{accept, connect, error::ProtocolError, Error, Message};
 use url::Url;
 
 #[test]
@@ -46,7 +46,7 @@ fn test_no_send_after_close() {
     assert!(err.is_err());
 
     match err.unwrap_err() {
-        Error::Protocol(s) => assert_eq!("Sending after closing is not allowed", s),
+        Error::Protocol(s) => assert_eq!(s, ProtocolError::SendAfterClosing),
         e => panic!("unexpected error: {:?}", e),
     }