refactor(client): improve connect module structure

src/client/connect/dns.rs

@@ -0,0 +1,100 @@
+use std::io;
+use std::net::{
+    Ipv4Addr, Ipv6Addr,
+    SocketAddr, ToSocketAddrs,
+    SocketAddrV4, SocketAddrV6,
+};
+use std::vec;
+
+use ::futures::{Async, Future, Poll};
+
+pub struct Work {
+    host: String,
+    port: u16
+}
+
+impl Work {
+    pub fn new(host: String, port: u16) -> Work {
+        Work { host: host, port: port }
+    }
+}
+
+impl Future for Work {
+    type Item = IpAddrs;
+    type Error = io::Error;
+
+    fn poll(&mut self) -> Poll<Self::Item, Self::Error> {
+        debug!("resolving host={:?}, port={:?}", self.host, self.port);
+        (&*self.host, self.port).to_socket_addrs()
+            .map(|i| Async::Ready(IpAddrs { iter: i }))
+    }
+}
+
+pub struct IpAddrs {
+    iter: vec::IntoIter<SocketAddr>,
+}
+
+impl IpAddrs {
+    pub fn new(addrs: Vec<SocketAddr>) -> Self {
+        IpAddrs { iter: addrs.into_iter() }
+    }
+
+    pub fn try_parse(host: &str, port: u16) -> Option<IpAddrs> {
+        if let Ok(addr) = host.parse::<Ipv4Addr>() {
+            let addr = SocketAddrV4::new(addr, port);
+            return Some(IpAddrs { iter: vec![SocketAddr::V4(addr)].into_iter() })
+        }
+        if let Ok(addr) = host.parse::<Ipv6Addr>() {
+            let addr = SocketAddrV6::new(addr, port, 0, 0);
+            return Some(IpAddrs { iter: vec![SocketAddr::V6(addr)].into_iter() })
+        }
+        None
+    }
+
+    pub fn split_by_preference(self) -> (IpAddrs, IpAddrs) {
+        let preferring_v6 = self.iter
+            .as_slice()
+            .first()
+            .map(SocketAddr::is_ipv6)
+            .unwrap_or(false);
+
+        let (preferred, fallback) = self.iter
+            .partition::<Vec<_>, _>(|addr| addr.is_ipv6() == preferring_v6);
+
+        (IpAddrs::new(preferred), IpAddrs::new(fallback))
+    }
+
+    pub fn is_empty(&self) -> bool {
+        self.iter.as_slice().is_empty()
+    }
+}
+
+impl Iterator for IpAddrs {
+    type Item = SocketAddr;
+    #[inline]
+    fn next(&mut self) -> Option<SocketAddr> {
+        self.iter.next()
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use std::net::{Ipv4Addr, Ipv6Addr};
+    use super::*;
+
+    #[test]
+    fn test_ip_addrs_split_by_preference() {
+        let v4_addr = (Ipv4Addr::new(127, 0, 0, 1), 80).into();
+        let v6_addr = (Ipv6Addr::new(0, 0, 0, 0, 0, 0, 0, 1), 80).into();
+
+        let (mut preferred, mut fallback) =
+            IpAddrs { iter: vec![v4_addr, v6_addr].into_iter() }.split_by_preference();
+        assert!(preferred.next().unwrap().is_ipv4());
+        assert!(fallback.next().unwrap().is_ipv6());
+
+        let (mut preferred, mut fallback) =
+            IpAddrs { iter: vec![v6_addr, v4_addr].into_iter() }.split_by_preference();
+        assert!(preferred.next().unwrap().is_ipv6());
+        assert!(fallback.next().unwrap().is_ipv4());
+    }
+}