Downloading the binaries through a proxy if either HTTPS_PROXY or HTT…

…P_PROXY environment variable is set.

closes #48

build.rs

@@ -114,10 +114,19 @@ mod download {
             );
             println!("url:{}", url);
             let mut downloaded_bytes = Vec::new();
-            let resp = ureq::get(&url).call().unwrap();
-            assert_eq!(resp.status(), 200, "url {} didn't return 200", url);
 
-            let _size = resp
+            let http_proxy = std::env::var("HTTPS_PROXY").or_else(|_| std::env::var("HTTP_PROXY"));
+            let agent = if let Ok(proxy) = http_proxy {
+                let proxy = ureq::Proxy::new(proxy).unwrap();
+                ureq::AgentBuilder::new().proxy(proxy).build()
+            } else {
+                ureq::AgentBuilder::new().build()
+            };
+
+            let _size = agent
+                .get(&url)
+                .call()
+                .unwrap()
                 .into_reader()
                 .read_to_end(&mut downloaded_bytes)
                 .unwrap();