Merge pull request #10067 from ramboman/fix-proxy-nix

`nix`: Fix `haveInternet` to check for proxy

(cherry picked from commit accae60e7710a18f6f2bd7d2f4cd836bcd76b684)
Change-Id: I996dafdcd266f4bc5806386c86b19040120842bf

src/nix/main.cc

@@ -27,6 +27,24 @@ void chrootHelper(int argc, char * * argv);
 
 namespace nix {
 
+static bool haveProxyEnvironmentVariables()
+{
+    static const std::vector<std::string> proxyVariables = {
+        "http_proxy",
+        "https_proxy",
+        "ftp_proxy",
+        "HTTP_PROXY",
+        "HTTPS_PROXY",
+        "FTP_PROXY"
+    };
+    for (auto & proxyVariable: proxyVariables) {
+        if (getEnv(proxyVariable).has_value()) {
+            return true;
+        }
+    }
+    return false;
+}
+
 /* Check if we have a non-loopback/link-local network interface. */
 static bool haveInternet()
 {
@@ -50,6 +68,8 @@ static bool haveInternet()
         }
     }
 
+    if (haveProxyEnvironmentVariables()) return true;
+
     return false;
 }