add global dns cache

Cargo.lock

@@ -14,6 +14,7 @@ dependencies = [
  "libc 0.2.21 (registry+https://github.com/rust-lang/crates.io-index)",
  "log 0.3.7 (registry+https://github.com/rust-lang/crates.io-index)",
  "lru-cache 0.1.0 (registry+https://github.com/rust-lang/crates.io-index)",
+ "lru_time_cache 0.6.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "net2 0.2.27 (registry+https://github.com/rust-lang/crates.io-index)",
  "num_cpus 1.3.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "openssl 0.9.9 (registry+https://github.com/rust-lang/crates.io-index)",
@@ -313,6 +314,11 @@ dependencies = [
  "linked-hash-map 0.2.1 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
+[[package]]
+name = "lru_time_cache"
+version = "0.6.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+
 [[package]]
 name = "lzw"
 version = "0.10.0"
@@ -713,6 +719,7 @@ dependencies = [
 "checksum linked-hash-map 0.2.1 (registry+https://github.com/rust-lang/crates.io-index)" = "bda158e0dabeb97ee8a401f4d17e479d6b891a14de0bba79d5cc2d4d325b5e48"
 "checksum log 0.3.7 (registry+https://github.com/rust-lang/crates.io-index)" = "5141eca02775a762cc6cd564d8d2c50f67c0ea3a372cbf1c51592b3e029e10ad"
 "checksum lru-cache 0.1.0 (registry+https://github.com/rust-lang/crates.io-index)" = "656fa4dfcb02bcf1063c592ba3ff6a5303ee1f2afe98c8a889e8b1a77c6dfdb7"
+"checksum lru_time_cache 0.6.0 (registry+https://github.com/rust-lang/crates.io-index)" = "4bf17862cdf1a87c7cc0cccc498552f3e564d2ae61069f83d2279a932af4a00c"
 "checksum lzw 0.10.0 (registry+https://github.com/rust-lang/crates.io-index)" = "7d947cbb889ed21c2a84be6ffbaebf5b4e0f4340638cba0444907e38b56be084"
 "checksum memchr 1.0.1 (registry+https://github.com/rust-lang/crates.io-index)" = "1dbccc0e46f1ea47b9f17e6d67c5a96bd27030519c519c9c91327e31275a47b4"
 "checksum mio 0.6.5 (registry+https://github.com/rust-lang/crates.io-index)" = "aa30e3753079b08ce3d75cf3b44783e36fe0e1f64065f65c1d894d1688fb2580"

Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "shadowsocks-rust"
-version = "1.3.1"
+version = "1.3.2"
 authors = ["Y. T. CHUNG <zonyitoo@gmail.com>"]
 description = "shadowsocks is a fast tunnel proxy that helps you bypass firewalls."
 repository = "https://github.com/zonyitoo/shadowsocks-rust"
@@ -38,6 +38,7 @@ env_logger = "0.4"
 rust-crypto = "0.2"
 openssl = "0.9"
 lru-cache = "0.1"
+lru_time_cache = "0.6"
 libc = "0.2"
 futures = "0.1"
 tokio-core = "0.1"

src/lib.rs

@@ -74,6 +74,7 @@ extern crate serde_json;
 #[macro_use]
 extern crate log;
 extern crate lru_cache;
+extern crate lru_time_cache;
 
 extern crate byteorder;
 extern crate rand;

src/relay/dns_resolver.rs

@@ -1,6 +1,8 @@
 //! Asynchronous DNS resolver
 
 use std::io;
+use std::time::Duration;
+use std::cell::RefCell;
 
 use futures::{Future, BoxFuture};
 use futures::future;
@@ -11,13 +13,28 @@ use domain::resolv::Resolver;
 use domain::resolv::lookup::lookup_host;
 use domain::bits::DNameBuf;
 
+use lru_time_cache::LruCache;
+
 use std::net::IpAddr;
 
+// Global DNS cache.
+// Cache for 5mins and store at most 128 entries
+thread_local!(static GLOBAL_DNS_CACHE: RefCell<LruCache<String, IpAddr>>
+    = RefCell::new(LruCache::with_expiry_duration_and_capacity(Duration::from_secs(5 * 60), 128)));
+
 pub fn resolve(addr: &str, handle: &Handle) -> BoxFuture<IpAddr, io::Error> {
+    let cached_addr = GLOBAL_DNS_CACHE.with(|c| {
+                                                let mut xc = c.borrow_mut();
+                                                xc.get(addr).map(|x| *x)
+                                            });
+
+    if let Some(addr) = cached_addr {
+        return future::finished(addr).boxed();
+    }
+
     let dname = match addr.parse::<DNameBuf>() {
         Ok(dname) => dname,
-        Err(err) => return future::err(io::Error::new(io::ErrorKind::Other, err))
-            .boxed()
+        Err(err) => return future::err(io::Error::new(io::ErrorKind::Other, err)).boxed(),
     };
     let resolv = Resolver::new(handle);
 
@@ -25,18 +42,22 @@ pub fn resolve(addr: &str, handle: &Handle) -> BoxFuture<IpAddr, io::Error> {
 
     lookup_host(resolv, &dname)
         .map_err(From::from)
-        .and_then(move |hosts| {
-            match hosts.iter().next() {
-                Some(addr) => {
-                    trace!("Resolved \"{}\" as {}", dname, addr);
-                    Ok(addr)
-                }
-                None => {
-                    let err = io::Error::new(io::ErrorKind::Other,
-                                             format!("Failed to resolve \"{}\"", dname));
-                    Err(err)
-                }
-            }
-        })
+        .and_then(move |hosts| match hosts.iter().next() {
+                      Some(addr) => {
+                          trace!("Resolved \"{}\" as {}", dname, addr);
+
+                          GLOBAL_DNS_CACHE.with(|c| {
+                                                    let mut xc = c.borrow_mut();
+                                                    xc.insert(dname.to_string(), addr);
+                                                });
+
+                          Ok(addr)
+                      }
+                      None => {
+                          let err = io::Error::new(io::ErrorKind::Other,
+                                                   format!("Failed to resolve \"{}\"", dname));
+                          Err(err)
+                      }
+                  })
         .boxed()
 }