1 files changed, 72 insertions, 0 deletions
diff --git a/runtime/resolve_addr.rs b/runtime/resolve_addr.rs
new file mode 100644
index 000000000..c3dc52f8f
--- /dev/null
+++ b/runtime/resolve_addr.rs
@@ -0,0 +1,72 @@
+// Copyright 2018-2020 the Deno authors. All rights reserved. MIT license.
+
+use deno_core::error::AnyError;
+use std::net::SocketAddr;
+use std::net::ToSocketAddrs;
+
+/// Resolve network address. Returns a future.
+pub fn resolve_addr(hostname: &str, port: u16) -> Result<SocketAddr, AnyError> {
+  // Default to localhost if given just the port. Example: ":80"
+  let addr: &str = if !hostname.is_empty() {
+    &hostname
+  } else {
+    "0.0.0.0"
+  };
+
+  // If this looks like an ipv6 IP address. Example: "[2001:db8::1]"
+  // Then we remove the brackets.
+  let addr = if addr.starts_with('[') && addr.ends_with(']') {
+    let l = addr.len() - 1;
+    addr.get(1..l).unwrap()
+  } else {
+    addr
+  };
+  let addr_port_pair = (addr, port);
+  let mut iter = addr_port_pair.to_socket_addrs()?;
+  Ok(iter.next().unwrap())
+}
+
+#[cfg(test)]
+mod tests {
+  use super::*;
+  use std::net::Ipv4Addr;
+  use std::net::Ipv6Addr;
+  use std::net::SocketAddrV4;
+  use std::net::SocketAddrV6;
+
+  #[test]
+  fn resolve_addr1() {
+    let expected =
+      SocketAddr::V4(SocketAddrV4::new(Ipv4Addr::new(127, 0, 0, 1), 80));
+    let actual = resolve_addr("127.0.0.1", 80).unwrap();
+    assert_eq!(actual, expected);
+  }
+
+  #[test]
+  fn resolve_addr2() {
+    let expected =
+      SocketAddr::V4(SocketAddrV4::new(Ipv4Addr::new(0, 0, 0, 0), 80));
+    let actual = resolve_addr("", 80).unwrap();
+    assert_eq!(actual, expected);
+  }
+
+  #[test]
+  fn resolve_addr3() {
+    let expected =
+      SocketAddr::V4(SocketAddrV4::new(Ipv4Addr::new(192, 0, 2, 1), 25));
+    let actual = resolve_addr("192.0.2.1", 25).unwrap();
+    assert_eq!(actual, expected);
+  }
+
+  #[test]
+  fn resolve_addr_ipv6() {
+    let expected = SocketAddr::V6(SocketAddrV6::new(
+      Ipv6Addr::new(0x2001, 0xdb8, 0, 0, 0, 0, 0, 1),
+      8080,
+      0,
+      0,
+    ));
+    let actual = resolve_addr("[2001:db8::1]", 8080).unwrap();
+    assert_eq!(actual, expected);
+  }
+}