move error handler to a separate module

src/error.rs

@@ -0,0 +1,50 @@
+#[derive(Debug)]
+pub struct Error {
+    message: String,
+}
+
+pub fn s2e(s: &str) -> Error {
+    Error::from(s)
+}
+
+impl From<std::io::Error> for Error {
+    fn from(err: std::io::Error) -> Self {
+        Self {
+            message: err.to_string(),
+        }
+    }
+}
+
+impl From<&str> for Error {
+    fn from(err: &str) -> Self {
+        Self {
+            message: err.to_string(),
+        }
+    }
+}
+
+impl From<String> for Error {
+    fn from(err: String) -> Self {
+        Self { message: err }
+    }
+}
+
+impl From<&String> for Error {
+    fn from(err: &String) -> Self {
+        Self {
+            message: err.to_string(),
+        }
+    }
+}
+
+impl std::fmt::Display for Error {
+    fn fmt(&self, f: &mut std::fmt::Formatter) -> std::fmt::Result {
+        write!(f, "{}", self.message)
+    }
+}
+
+impl std::error::Error for Error {
+    fn description(&self) -> &str {
+        &self.message
+    }
+}

src/http.rs

@@ -1,6 +1,7 @@
+use crate::error::Error;
 use crate::tun2proxy::{
     Connection, ConnectionManager, Credentials, IncomingDataEvent, IncomingDirection,
-    OutgoingDataEvent, OutgoingDirection, ProxyError, TcpProxy,
+    OutgoingDataEvent, OutgoingDirection, TcpProxy,
 };
 use base64::Engine;
 use std::collections::VecDeque;
@@ -58,7 +59,7 @@ impl HttpConnection {
         }
     }
 
-    fn state_change(&mut self) -> Result<(), ProxyError> {
+    fn state_change(&mut self) -> Result<(), Error> {
         match self.state {
             HttpState::ExpectStatusCode if self.server_inbuf.len() >= "HTTP/1.1 200 ".len() => {
                 let status_line: Vec<u8> = self
@@ -72,11 +73,9 @@ impl HttpConnection {
                 {
                     let status_str =
                         String::from_utf8_lossy(&status_line.as_slice()[0.."HTTP/1.1 200".len()]);
-                    return Err(ProxyError::new(
+                    let e =
-                        "Expected success status code. Server replied with ".to_owned()
+                        format!("Expected success status code. Server replied with {status_str}.");
-                            + &*status_str
+                    return Err(e.into());
-                            + ".",
-                    ));
                 }
                 self.state = HttpState::ExpectResponse;
                 return self.state_change();
@@ -118,7 +117,7 @@ impl HttpConnection {
 }
 
 impl TcpProxy for HttpConnection {
-    fn push_data(&mut self, event: IncomingDataEvent<'_>) -> Result<(), ProxyError> {
+    fn push_data(&mut self, event: IncomingDataEvent<'_>) -> Result<(), Error> {
         let direction = event.direction;
         let buffer = event.buffer;
         match direction {

src/lib.rs

@@ -1,7 +1,9 @@
+use crate::error::{s2e, Error};
 use crate::tun2proxy::Credentials;
 use crate::{http::HttpManager, socks5::Socks5Manager, tun2proxy::TunToProxy};
 use std::net::{SocketAddr, ToSocketAddrs};
 
+pub mod error;
 pub mod http;
 pub mod socks5;
 pub mod tun2proxy;
@@ -15,24 +17,23 @@ pub struct Proxy {
 }
 
 impl Proxy {
-    pub fn from_url(s: &str) -> Result<Proxy, String> {
+    pub fn from_url(s: &str) -> Result<Proxy, Error> {
-        let url = url::Url::parse(s).map_err(|_| format!("`{s}` is not a valid proxy URL"))?;
+        let e = format!("`{s}` is not a valid proxy URL");
-        let host = url
+        let url = url::Url::parse(s).map_err(|_| s2e(&e))?;
-            .host_str()
+        let e = format!("`{s}` does not contain a host");
-            .ok_or(format!("`{s}` does not contain a host"))?;
+        let host = url.host_str().ok_or(s2e(&e))?;
 
         let mut url_host = String::from(host);
-        let port = url.port().ok_or(format!("`{s}` does not contain a port"))?;
+        let e = format!("`{s}` does not contain a port");
+        let port = url.port().ok_or(s2e(&e))?;
         url_host.push(':');
         url_host.push_str(port.to_string().as_str());
 
-        let mut addr_iter = url_host
+        let e = format!("`{host}` could not be resolved");
-            .to_socket_addrs()
+        let mut addr_iter = url_host.to_socket_addrs().map_err(|_| s2e(&e))?;
-            .map_err(|_| format!("`{host}` could not be resolved"))?;
 
-        let addr = addr_iter
+        let e = format!("`{host}` does not resolve to a usable IP address");
-            .next()
+        let addr = addr_iter.next().ok_or(s2e(&e))?;
-            .ok_or(format!("`{host}` does not resolve to a usable IP address"))?;
 
         let credentials = if url.username() == "" && url.password().is_none() {
             None
@@ -49,7 +50,7 @@ impl Proxy {
             "http" => Some(ProxyType::Http),
             _ => None,
         }
-        .ok_or(format!("`{scheme}` is an invalid proxy type"))?;
+        .ok_or(s2e(&format!("`{scheme}` is an invalid proxy type")))?;
 
         Ok(Proxy {
             proxy_type,

src/socks5.rs

@@ -1,6 +1,7 @@
+use crate::error::Error;
 use crate::tun2proxy::{
     Connection, ConnectionManager, Credentials, IncomingDataEvent, IncomingDirection,
-    OutgoingDataEvent, OutgoingDirection, ProxyError, TcpProxy,
+    OutgoingDataEvent, OutgoingDirection, TcpProxy,
 };
 use std::collections::VecDeque;
 use std::net::{IpAddr, SocketAddr};
@@ -90,22 +91,18 @@ impl SocksConnection {
         self.state = SocksState::ServerHello;
     }
 
-    fn receive_server_hello(&mut self) -> Result<(), ProxyError> {
+    fn receive_server_hello(&mut self) -> Result<(), Error> {
         if self.server_inbuf.len() < 2 {
             return Ok(());
         }
         if self.server_inbuf[0] != 5 {
-            return Err(ProxyError::new(
+            return Err("SOCKS server replied with an unexpected version.".into());
-                "SOCKS server replied with an unexpected version.".into(),
-            ));
         }
 
         if self.server_inbuf[1] != 0 && self.manager.get_credentials().is_none()
             || self.server_inbuf[1] != 2 && self.manager.get_credentials().is_some()
         {
-            return Err(ProxyError::new(
+            return Err("SOCKS server requires an unsupported authentication method.".into());
-                "SOCKS server requires an unsupported authentication method.".into(),
-            ));
         }
 
         self.server_inbuf.drain(0..2);
@@ -118,7 +115,7 @@ impl SocksConnection {
         self.state_change()
     }
 
-    fn send_auth_data(&mut self) -> Result<(), ProxyError> {
+    fn send_auth_data(&mut self) -> Result<(), Error> {
         let tmp = Credentials::default();
         let credentials = self.manager.get_credentials().as_ref().unwrap_or(&tmp);
         self.server_outbuf
@@ -131,19 +128,19 @@ impl SocksConnection {
         self.state_change()
     }
 
-    fn receive_auth_data(&mut self) -> Result<(), ProxyError> {
+    fn receive_auth_data(&mut self) -> Result<(), Error> {
         if self.server_inbuf.len() < 2 {
             return Ok(());
         }
         if self.server_inbuf[0] != 1 || self.server_inbuf[1] != 0 {
-            return Err(ProxyError::new("SOCKS authentication failed.".into()));
+            return Err("SOCKS authentication failed.".into());
         }
         self.server_inbuf.drain(0..2);
         self.state = SocksState::SendRequest;
         self.state_change()
     }
 
-    fn receive_connection_status(&mut self) -> Result<(), ProxyError> {
+    fn receive_connection_status(&mut self) -> Result<(), Error> {
         if self.server_inbuf.len() < 4 {
             return Ok(());
         }
@@ -153,22 +150,18 @@ impl SocksConnection {
         let atyp = self.server_inbuf[3];
 
         if ver != 5 {
-            return Err(ProxyError::new(
+            return Err("SOCKS server replied with an unexpected version.".into());
-                "SOCKS server replied with an unexpected version.".into(),
-            ));
         }
 
         if rep != 0 {
-            return Err(ProxyError::new("SOCKS connection unsuccessful.".into()));
+            return Err("SOCKS connection unsuccessful.".into());
         }
 
         if atyp != SocksAddressType::Ipv4 as u8
             && atyp != SocksAddressType::Ipv6 as u8
             && atyp != SocksAddressType::DomainName as u8
         {
-            return Err(ProxyError::new(
+            return Err("SOCKS server replied with unrecognized address type.".into());
-                "SOCKS server replied with unrecognized address type.".into(),
-            ));
         }
 
         if atyp == SocksAddressType::DomainName as u8 && self.server_inbuf.len() < 5 {
@@ -197,7 +190,7 @@ impl SocksConnection {
         self.state_change()
     }
 
-    fn send_request(&mut self) -> Result<(), ProxyError> {
+    fn send_request(&mut self) -> Result<(), Error> {
         let dst_ip = self.connection.dst.ip();
         let cmd = if dst_ip.is_ipv4() { 1 } else { 4 };
         self.server_outbuf.extend(&[5u8, 1, 0, cmd]);
@@ -213,7 +206,7 @@ impl SocksConnection {
         self.state_change()
     }
 
-    pub fn state_change(&mut self) -> Result<(), ProxyError> {
+    pub fn state_change(&mut self) -> Result<(), Error> {
         match self.state {
             SocksState::ServerHello => self.receive_server_hello(),
 
@@ -239,7 +232,7 @@ impl SocksConnection {
 }
 
 impl TcpProxy for SocksConnection {
-    fn push_data(&mut self, event: IncomingDataEvent<'_>) -> Result<(), ProxyError> {
+    fn push_data(&mut self, event: IncomingDataEvent<'_>) -> Result<(), Error> {
         let direction = event.direction;
         let buffer = event.buffer;
         match direction {

src/tun2proxy.rs

@@ -1,3 +1,4 @@
+use crate::error::Error;
 use crate::virtdevice::VirtualTunDevice;
 use log::{error, info};
 use mio::event::Event;
@@ -18,20 +19,6 @@ use std::net::Shutdown::Both;
 use std::net::{IpAddr, Shutdown, SocketAddr};
 use std::os::unix::io::AsRawFd;
 
-pub struct ProxyError {
-    message: String,
-}
-
-impl ProxyError {
-    pub fn new(message: String) -> Self {
-        Self { message }
-    }
-
-    pub fn message(&self) -> String {
-        self.message.clone()
-    }
-}
-
 #[derive(Hash, Clone, Copy, Eq, PartialEq)]
 pub struct Connection {
     pub src: std::net::SocketAddr,
@@ -178,7 +165,7 @@ impl Credentials {
 }
 
 pub(crate) trait TcpProxy {
-    fn push_data(&mut self, event: IncomingDataEvent<'_>) -> Result<(), ProxyError>;
+    fn push_data(&mut self, event: IncomingDataEvent<'_>) -> Result<(), Error>;
     fn consume_data(&mut self, dir: OutgoingDirection, size: usize);
     fn peek_data(&mut self, dir: OutgoingDirection) -> OutgoingDataEvent;
     fn connection_established(&self) -> bool;
@@ -302,10 +289,6 @@ impl<'a> TunToProxy<'a> {
         None
     }
 
-    fn print_error(error: ProxyError) {
-        error!("{}", error.message());
-    }
-
     fn tunsocket_read_and_forward(&mut self, connection: &Connection) {
         if let Some(state) = self.connections.get_mut(connection) {
             let closed = {
@@ -329,7 +312,7 @@ impl<'a> TunToProxy<'a> {
                 match error {
                     Ok(_) => socket.state() == smoltcp::socket::tcp::State::CloseWait,
                     Err(e) => {
-                        Self::print_error(e);
+                        log::error!("{e}");
                         true
                     }
                 }
@@ -512,7 +495,7 @@ impl<'a> TunToProxy<'a> {
                             socket.close();
                         }
                         self.expect_smoltcp_send();
-                        Self::print_error(error);
+                        log::error! {"{error}"};
                         self.remove_connection(&connection.clone());
                         return;
                     }