Remove trust-dns when target_os is Android

.travis.yml

@@ -26,6 +26,13 @@ matrix:
         - rust: stable
           env: FEATURES="--features hyper-011"
 
+        # android
+        - rust: stable
+          env: TARGET=aarch64-linux-android
+          install: rustup target add "$TARGET"
+          # disable default-tls feature since cross-compiling openssl is dragons
+          script: cargo build --target "$TARGET" --no-default-features
+
         # minimum version
         - rust: 1.30.0
           script: cargo build

Cargo.toml

@@ -31,7 +31,6 @@ tokio-executor = "0.1.4" # a minimum version so trust-dns-resolver compiles
 tokio-io = "0.1"
 tokio-threadpool = "0.1.8" # a minimum version so tokio compiles
 tokio-timer = "0.2.6" # a minimum version so trust-dns-resolver compiles
-trust-dns-resolver = "0.10"
 url = "1.2"
 uuid = { version = "0.7", features = ["v4"] }
 hyper-rustls = { version = "0.15", optional = true }
@@ -39,6 +38,9 @@ tokio-rustls = { version = "0.8", optional = true }
 webpki-roots = { version = "0.15", optional = true }
 rustls = { version = "0.14", features = ["dangerous_configuration"], optional = true }
 
+[target.'cfg(not(target_os = "android"))'.dependencies]
+trust-dns-resolver = "0.10"
+
 [dev-dependencies]
 env_logger = "0.6"
 serde_derive = "1.0"

src/connect.rs

@@ -13,10 +13,14 @@ use bytes::BufMut;
 use std::io;
 use std::sync::Arc;
 
+#[cfg(not(target_os = "android"))]
 use dns::TrustDnsResolver;
 use Proxy;
 
+#[cfg(not(target_os = "android"))]
 type HttpConnector = ::hyper::client::HttpConnector<TrustDnsResolver>;
+#[cfg(target_os = "android")]
+type HttpConnector = ::hyper::client::HttpConnector;
 
 
 pub(crate) struct Connector {
@@ -70,12 +74,18 @@ impl Connector {
     }
 }
 
+#[cfg(not(target_os = "android"))]
 fn http_connector() -> ::Result<HttpConnector> {
     TrustDnsResolver::new()
         .map(HttpConnector::new_with_resolver)
         .map_err(::error::dns_system_conf)
 }
 
+#[cfg(target_os = "android")]
+fn http_connector() -> ::Result<HttpConnector> {
+    Ok(HttpConnector::new(4))
+}
+
 impl Connect for Connector {
     type Transport = Conn;
     type Error = io::Error;

src/lib.rs

@@ -196,6 +196,7 @@ extern crate serde_urlencoded;
 extern crate tokio;
 #[cfg_attr(feature = "default-tls", macro_use)]
 extern crate tokio_io;
+#[cfg(not(target_os = "android"))]
 extern crate trust_dns_resolver;
 extern crate url;
 extern crate uuid;
@@ -237,6 +238,7 @@ mod connect;
 mod connect_async;
 mod body;
 mod client;
+#[cfg(not(target_os = "android"))]
 mod dns;
 mod into_url;
 mod proxy;