RUST-802 Support Unix Domain Sockets (mongodb#908)

Author: PureWhiteWu

src/client/auth.rs

@@ -397,29 +397,6 @@ pub struct Credential {
 }
 
 impl Credential {
-    #[cfg(all(test, not(feature = "sync"), not(feature = "tokio-sync")))]
-    pub(crate) fn into_document(mut self) -> Document {
-        use crate::bson::Bson;
-
-        let mut doc = Document::new();
-
-        if let Some(s) = self.username.take() {
-            doc.insert("username", s);
-        }
-
-        if let Some(s) = self.password.take() {
-            doc.insert("password", s);
-        } else {
-            doc.insert("password", Bson::Null);
-        }
-
-        if let Some(s) = self.source.take() {
-            doc.insert("db", s);
-        }
-
-        doc
-    }
-
     pub(crate) fn resolved_source(&self) -> &str {
         self.mechanism
             .as_ref()

src/client/options.rs

@@ -4,6 +4,7 @@ mod test;
 mod resolver_config;
 
 use std::{
+    borrow::Cow,
     cmp::Ordering,
     collections::HashSet,
     convert::TryFrom,
@@ -91,14 +92,11 @@ lazy_static! {
     };
 
     static ref ILLEGAL_DATABASE_CHARACTERS: HashSet<&'static char> = {
-        ['/', '\\', ' ', '"', '$', '.'].iter().collect()
+        ['/', '\\', ' ', '"', '$'].iter().collect()
     };
 }
 
 /// An enum representing the address of a MongoDB server.
-///
-/// Currently this just supports addresses that can be connected to over TCP, but alternative
-/// address types may be supported in the future (e.g. Unix Domain Socket paths).
 #[derive(Clone, Debug, Eq, Serialize)]
 #[non_exhaustive]
 pub enum ServerAddress {
@@ -112,6 +110,12 @@ pub enum ServerAddress {
         /// The default is 27017.
         port: Option<u16>,
     },
+    /// A Unix Domain Socket path.
+    #[cfg(unix)]
+    Unix {
+        /// The path to the Unix Domain Socket.
+        path: PathBuf,
+    },
 }
 
 impl<'de> Deserialize<'de> for ServerAddress {
@@ -144,6 +148,10 @@ impl PartialEq for ServerAddress {
                     port: other_port,
                 },
             ) => host == other_host && port.unwrap_or(27017) == other_port.unwrap_or(27017),
+            #[cfg(unix)]
+            (Self::Unix { path }, Self::Unix { path: other_path }) => path == other_path,
+            #[cfg(unix)]
+            _ => false,
         }
     }
 }
@@ -158,6 +166,8 @@ impl Hash for ServerAddress {
                 host.hash(state);
                 port.unwrap_or(27017).hash(state);
             }
+            #[cfg(unix)]
+            Self::Unix { path } => path.hash(state),
         }
     }
 }
@@ -173,6 +183,15 @@ impl ServerAddress {
     /// Parses an address string into a `ServerAddress`.
     pub fn parse(address: impl AsRef<str>) -> Result<Self> {
         let address = address.as_ref();
+        // checks if the address is a unix domain socket
+        #[cfg(unix)]
+        {
+            if address.ends_with(".sock") {
+                return Ok(ServerAddress::Unix {
+                    path: PathBuf::from(address),
+                });
+            }
+        }
         let mut parts = address.split(':');
         let hostname = match parts.next() {
             Some(part) => {
@@ -243,18 +262,29 @@ impl ServerAddress {
                     "port": port.map(|i| Bson::Int32(i.into())).unwrap_or(Bson::Null)
                 }
             }
+            #[cfg(unix)]
+            Self::Unix { path } => {
+                doc! {
+                    "host": path.to_string_lossy().as_ref(),
+                    "port": Bson::Null,
+                }
+            }
         }
     }
 
-    pub(crate) fn host(&self) -> &str {
+    pub(crate) fn host(&self) -> Cow<'_, str> {
         match self {
-            Self::Tcp { host, .. } => host.as_str(),
+            Self::Tcp { host, .. } => Cow::Borrowed(host.as_str()),
+            #[cfg(unix)]
+            Self::Unix { path } => path.to_string_lossy(),
         }
     }
 
     pub(crate) fn port(&self) -> Option<u16> {
         match self {
             Self::Tcp { port, .. } => *port,
+            #[cfg(unix)]
+            Self::Unix { .. } => None,
         }
     }
 }
@@ -265,6 +295,8 @@ impl fmt::Display for ServerAddress {
             Self::Tcp { host, port } => {
                 write!(fmt, "{}:{}", host, port.unwrap_or(DEFAULT_PORT))
             }
+            #[cfg(unix)]
+            Self::Unix { path } => write!(fmt, "{}", path.display()),
         }
     }
 }
@@ -1580,10 +1612,26 @@ impl ConnectionString {
             None => (None, None),
         };
 
-        let host_list: Result<Vec<_>> =
-            hosts_section.split(',').map(ServerAddress::parse).collect();
-
-        let host_list = host_list?;
+        let mut host_list = Vec::with_capacity(hosts_section.len());
+        for host in hosts_section.split(',') {
+            let address = if host.ends_with(".sock") {
+                #[cfg(unix)]
+                {
+                    ServerAddress::parse(percent_decode(
+                        host,
+                        "Unix domain sockets must be URL-encoded",
+                    )?)
+                }
+                #[cfg(not(unix))]
+                return Err(ErrorKind::InvalidArgument {
+                    message: "Unix domain sockets are not supported on this platform".to_string(),
+                }
+                .into());
+            } else {
+                ServerAddress::parse(host)
+            }?;
+            host_list.push(address);
+        }
 
         let hosts = if srv {
             if host_list.len() != 1 {
@@ -1592,16 +1640,26 @@ impl ConnectionString {
                 }
                 .into());
             }
-            // Unwrap safety: the `len` check above guarantees this can't fail.
-            let ServerAddress::Tcp { host, port } = host_list.into_iter().next().unwrap();
 
-            if port.is_some() {
-                return Err(ErrorKind::InvalidArgument {
-                    message: "a port cannot be specified with 'mongodb+srv'".into(),
+            // Unwrap safety: the `len` check above guarantees this can't fail.
+            match host_list.into_iter().next().unwrap() {
+                ServerAddress::Tcp { host, port } => {
+                    if port.is_some() {
+                        return Err(ErrorKind::InvalidArgument {
+                            message: "a port cannot be specified with 'mongodb+srv'".into(),
+                        }
+                        .into());
+                    }
+                    HostInfo::DnsRecord(host)
+                }
+                #[cfg(unix)]
+                ServerAddress::Unix { .. } => {
+                    return Err(ErrorKind::InvalidArgument {
+                        message: "unix sockets cannot be used with 'mongodb+srv'".into(),
+                    }
+                    .into());
                 }
-                .into());
             }
-            HostInfo::DnsRecord(host)
         } else {
             HostInfo::HostIdentifiers(host_list)
         };
@@ -2299,18 +2357,39 @@ mod tests {
     #[test]
     fn test_parse_address_with_from_str() {
         let x = "localhost:27017".parse::<ServerAddress>().unwrap();
-        let ServerAddress::Tcp { host, port } = x;
-        assert_eq!(host, "localhost");
-        assert_eq!(port, Some(27017));
+        match x {
+            ServerAddress::Tcp { host, port } => {
+                assert_eq!(host, "localhost");
+                assert_eq!(port, Some(27017));
+            }
+            #[cfg(unix)]
+            _ => panic!("expected ServerAddress::Tcp"),
+        }
 
         // Port defaults to 27017 (so this doesn't fail)
         let x = "localhost".parse::<ServerAddress>().unwrap();
-        let ServerAddress::Tcp { host, port } = x;
-        assert_eq!(host, "localhost");
-        assert_eq!(port, None);
+        match x {
+            ServerAddress::Tcp { host, port } => {
+                assert_eq!(host, "localhost");
+                assert_eq!(port, None);
+            }
+            #[cfg(unix)]
+            _ => panic!("expected ServerAddress::Tcp"),
+        }
 
         let x = "localhost:not a number".parse::<ServerAddress>();
         assert!(x.is_err());
+
+        #[cfg(unix)]
+        {
+            let x = "/path/to/socket.sock".parse::<ServerAddress>().unwrap();
+            match x {
+                ServerAddress::Unix { path } => {
+                    assert_eq!(path.to_str().unwrap(), "/path/to/socket.sock");
+                }
+                _ => panic!("expected ServerAddress::Unix"),
+            }
+        }
     }
 
     #[cfg_attr(feature = "tokio-runtime", tokio::test)]