Add support for downloading through proxies

Fixes #587.

--
MOS_MIGRATED_REVID=110785300

1 files changed, 51 insertions, 1 deletions

diff --git a/src/main/java/com/google/devtools/build/lib/bazel/repository/HttpDownloader.java b/src/main/java/com/google/devtools/build/lib/bazel/repository/HttpDownloader.java
index e14edbb8f1..3f1495012f 100644
--- a/src/main/java/com/google/devtools/build/lib/bazel/repository/HttpDownloader.java
+++ b/src/main/java/com/google/devtools/build/lib/bazel/repository/HttpDownloader.java
@@ -14,6 +14,8 @@
 
 package com.google.devtools.build.lib.bazel.repository;
 
+import com.google.common.annotations.VisibleForTesting;
+import com.google.common.base.Strings;
 import com.google.common.hash.Hasher;
 import com.google.common.hash.Hashing;
 import com.google.devtools.build.lib.events.Event;
@@ -30,6 +32,8 @@ import java.io.IOException;
 import java.io.InputStream;
 import java.io.OutputStream;
 import java.net.HttpURLConnection;
+import java.net.InetSocketAddress;
+import java.net.Proxy;
 import java.net.URL;
 import java.util.concurrent.Executors;
 import java.util.concurrent.ScheduledExecutorService;
@@ -175,12 +179,58 @@ public class HttpDownloader {
   }
 
   private InputStream getInputStream(URL url) throws IOException {
-    HttpURLConnection connection = (HttpURLConnection) url.openConnection();
+    HttpURLConnection connection = (HttpURLConnection) url.openConnection(
+        createProxyIfNeeded(url.getProtocol()));
     connection.setInstanceFollowRedirects(true);
     connection.connect();
     return connection.getInputStream();
   }
 
+  private static Proxy createProxyIfNeeded(String protocol) throws IOException {
+    if (protocol.equals("https")) {
+      return createProxy(System.getenv("HTTPS_PROXY"));
+    } else if (protocol.equals("http")) {
+      return createProxy(System.getenv("HTTP_PROXY"));
+    }
+    return Proxy.NO_PROXY;
+  }
+
+  @VisibleForTesting
+  static Proxy createProxy(String proxyAddress) throws IOException {
+    if (Strings.isNullOrEmpty(proxyAddress)) {
+      return Proxy.NO_PROXY;
+    }
+
+    // Split the proxyAddress into the protocol, address, and optional port. This does not use the
+    // URL class to avoid the DNS resolution it performs on creation.
+    int protocolIndex = proxyAddress.indexOf(':');
+    if (protocolIndex == -1) {
+      throw new IOException("No proxy protocol found for " + proxyAddress);
+    }
+    boolean https;
+    String protocol = proxyAddress.substring(0, protocolIndex);
+    if (protocol.equals("https")) {
+      https = true;
+    } else if (protocol.equals("http")) {
+      https = false;
+    } else {
+      throw new IOException("Invalid proxy protocol for " + proxyAddress);
+    }
+    int portIndex = proxyAddress.lastIndexOf(':');
+    if (protocolIndex == portIndex) {
+      // No port set, just the http: colon.
+      return new Proxy(Proxy.Type.HTTP, new InetSocketAddress(proxyAddress, https ? 443 : 80));
+    }
+
+    try {
+      return new Proxy(Proxy.Type.HTTP, new InetSocketAddress(
+          proxyAddress.substring(0, portIndex),
+          Integer.parseInt(proxyAddress.substring(portIndex + 1))));
+    } catch (NumberFormatException e) {
+      throw new IOException("Error parsing proxy port: " + proxyAddress);
+    }
+  }
+
   public static String getHash(Hasher hasher, Path path) throws IOException {
     byte byteBuffer[] = new byte[BUFFER_SIZE];
     try (InputStream stream = path.getInputStream()) {