Add support for Unix Sockets

* add support for Unix Sockets to Stream/RefinedTcpStream.
* add a 'pub use' for ClientConnection and Stream
* convert ClientConnection::new to take Into<Stream> instead of two
  RefinedTcpStreams.
* add a default SocketAddr value for if the stream returns an error.

Pull Request: https://github.com/tiny-http/tiny-http/pull/187

--- a/src/client.rs
+++ b/src/client.rs
@@ -10,6 +10,7 @@ use std::str::FromStr;
 use common::{HTTPVersion, Method};
 use util::RefinedTcpStream;
 use util::{SequentialReader, SequentialReaderBuilder, SequentialWriterBuilder};
+use util::Stream;
 
 use Request;
 
@@ -17,7 +18,7 @@ use Request;
 /// and return Request objects.
 pub struct ClientConnection {
     // address of the client
-    remote_addr: IoResult<SocketAddr>,
+    remote_addr: SocketAddr,
 
     // sequence of Readers to the stream, so that the data is not read in
     //  the wrong order
@@ -50,11 +51,11 @@ enum ReadError {
 
 impl ClientConnection {
     /// Creates a new ClientConnection that takes ownership of the TcpStream.
-    pub fn new(
-        write_socket: RefinedTcpStream,
-        mut read_socket: RefinedTcpStream,
-    ) -> ClientConnection {
-        let remote_addr = read_socket.peer_addr();
+    pub fn new<S>(stream: S) -> ClientConnection
+        where S: Into<Stream>
+    {
+        let (mut read_socket, write_socket) = RefinedTcpStream::new(stream);
+        let remote_addr = read_socket.peer_addr().unwrap_or(SocketAddr::from(([0,0,0,0], 0)));
         let secure = read_socket.secure();
 
         let mut source = SequentialReaderBuilder::new(BufReader::with_capacity(1024, read_socket));
@@ -152,7 +153,7 @@ impl ClientConnection {
             path,
             version.clone(),
             headers,
-            *self.remote_addr.as_ref().unwrap(),
+            self.remote_addr,
             data_source,
             writer,
         )
diff --git a/src/lib.rs b/src/lib.rs
index 40b5491..60e8dcc 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -117,8 +117,9 @@ use std::sync::Arc;
 use std::thread;
 use std::time::Duration;
 
-use client::ClientConnection;
+pub use client::ClientConnection;
 use util::MessagesQueue;
+pub use util::Stream;
 
 pub use common::{HTTPVersion, Header, HeaderField, Method, StatusCode};
 pub use request::{ReadWrite, Request};
@@ -297,27 +298,24 @@ impl Server {
             while !inside_close_trigger.load(Relaxed) {
                 let new_client = match server.accept() {
                     Ok((sock, _)) => {
-                        use util::RefinedTcpStream;
-                        let (read_closable, write_closable) = match ssl {
-                            None => RefinedTcpStream::new(sock),
+                        let stream = match ssl {
+                            None => sock,
                             #[cfg(feature = "ssl")]
                             Some(ref ssl) => {
                                 let ssl = openssl::ssl::Ssl::new(ssl).expect("Couldn't create ssl");
                                 // trying to apply SSL over the connection
                                 // if an error occurs, we just close the socket and resume listening
-                                let sock = match ssl.accept(sock) {
+                                match ssl.accept(sock) {
                                     Ok(s) => s,
-                                    Err(_) => continue,
-                                };
-
-                                RefinedTcpStream::new(sock)
-                            }
+                                    Err(_) => continue
+                                }
+                            },
                             #[cfg(not(feature = "ssl"))]
                             Some(_) => unreachable!(),
                         };
 
-                        Ok(ClientConnection::new(write_closable, read_closable))
-                    }
+                        Ok(ClientConnection::new(stream))
+                    },
                     Err(e) => Err(e),
                 };
 
diff --git a/src/util/mod.rs b/src/util/mod.rs
index 8abfb64..d775ee6 100644
--- a/src/util/mod.rs
+++ b/src/util/mod.rs
@@ -1,7 +1,7 @@
 pub use self::custom_stream::CustomStream;
 pub use self::equal_reader::EqualReader;
 pub use self::messages_queue::MessagesQueue;
-pub use self::refined_tcp_stream::RefinedTcpStream;
+pub use self::refined_tcp_stream::{RefinedTcpStream, Stream};
 pub use self::sequential::{SequentialReader, SequentialReaderBuilder};
 pub use self::sequential::{SequentialWriter, SequentialWriterBuilder};
 pub use self::task_pool::TaskPool;
diff --git a/src/util/refined_tcp_stream.rs b/src/util/refined_tcp_stream.rs
index 0c031a9..942a017 100644
--- a/src/util/refined_tcp_stream.rs
+++ b/src/util/refined_tcp_stream.rs
@@ -1,6 +1,7 @@
 use std::io::Result as IoResult;
 use std::io::{Read, Write};
 use std::net::{Shutdown, SocketAddr, TcpStream};
+use std::os::unix::net::UnixStream;
 
 #[cfg(feature = "ssl")]
 use openssl::ssl::SslStream;
@@ -17,6 +18,7 @@ pub enum Stream {
     Http(TcpStream),
     #[cfg(feature = "ssl")]
     Https(Arc<Mutex<SslStream<TcpStream>>>),
+    Unix(UnixStream),
 }
 
 impl From<TcpStream> for Stream {
@@ -34,6 +36,13 @@ impl From<SslStream<TcpStream>> for Stream {
     }
 }
 
+impl From<UnixStream> for Stream {
+    #[inline]
+    fn from(stream: UnixStream) -> Stream {
+        Stream::Unix(stream)
+    }
+}
+
 impl RefinedTcpStream {
     pub fn new<S>(stream: S) -> (RefinedTcpStream, RefinedTcpStream)
     where
@@ -45,6 +54,7 @@ impl RefinedTcpStream {
             Stream::Http(ref stream) => Stream::Http(stream.try_clone().unwrap()),
             #[cfg(feature = "ssl")]
             Stream::Https(ref stream) => Stream::Https(stream.clone()),
+            Stream::Unix(ref stream) => Stream::Unix(stream.try_clone().unwrap()),
         };
 
         let read = RefinedTcpStream {
@@ -69,6 +79,7 @@ impl RefinedTcpStream {
             Stream::Http(_) => false,
             #[cfg(feature = "ssl")]
             Stream::Https(_) => true,
+            Stream::Unix(_) => false,
         }
     }
 
@@ -77,6 +88,7 @@ impl RefinedTcpStream {
             Stream::Http(ref mut stream) => stream.peer_addr(),
             #[cfg(feature = "ssl")]
             Stream::Https(ref mut stream) => stream.lock().unwrap().get_ref().peer_addr(),
+            Stream::Unix(_) => Err(std::io::Error::new(std::io::ErrorKind::Other, "Peer addresses are not supported for Unix sockets")),
         }
     }
 }
@@ -94,6 +106,7 @@ impl Drop for RefinedTcpStream {
                     .get_mut()
                     .shutdown(Shutdown::Read)
                     .ok(),
+                Stream::Unix(ref mut stream) => stream.shutdown(Shutdown::Read).ok(),
             };
         }
 
@@ -108,6 +121,7 @@ impl Drop for RefinedTcpStream {
                     .get_mut()
                     .shutdown(Shutdown::Write)
                     .ok(),
+                Stream::Unix(ref mut stream) => stream.shutdown(Shutdown::Write).ok(),
             };
         }
     }
@@ -119,6 +133,7 @@ impl Read for RefinedTcpStream {
             Stream::Http(ref mut stream) => stream.read(buf),
             #[cfg(feature = "ssl")]
             Stream::Https(ref mut stream) => stream.lock().unwrap().read(buf),
+            Stream::Unix(ref mut stream) => stream.read(buf),
         }
     }
 }
@@ -129,6 +144,7 @@ impl Write for RefinedTcpStream {
             Stream::Http(ref mut stream) => stream.write(buf),
             #[cfg(feature = "ssl")]
             Stream::Https(ref mut stream) => stream.lock().unwrap().write(buf),
+            Stream::Unix(ref mut stream) => stream.write(buf),
         }
     }
 
@@ -137,6 +153,7 @@ impl Write for RefinedTcpStream {
             Stream::Http(ref mut stream) => stream.flush(),
             #[cfg(feature = "ssl")]
             Stream::Https(ref mut stream) => stream.lock().unwrap().flush(),
+            Stream::Unix(ref mut stream) => stream.flush(),
         }
     }
 }