Template: perform a HEAD request to check file size from a URL

Signed-off-by: Marc-Aurèle Brothier <m@brothier.org>

Author: marcaurele

utils/src/main/java/com/cloud/utils/UriUtils.java

@@ -35,8 +35,6 @@
 import java.util.ListIterator;
 import java.util.StringTokenizer;
 
-import javax.net.ssl.HttpsURLConnection;
-
 import org.apache.commons.httpclient.Credentials;
 import org.apache.commons.httpclient.HttpClient;
 import org.apache.commons.httpclient.HttpException;
@@ -201,40 +199,53 @@ private static List<NameValuePair> getUserDetails(String query) {
         return details;
     }
 
+    public static void main(String[] args) {
+        long size = getRemoteSize("http://localhost:8000/systemvm/target/systemvm.zip");
+        System.out.println(size);
+    }
+
     // Get the size of a file from URL response header.
-    public static Long getRemoteSize(String url) {
-        Long remoteSize = (long)0;
-        HttpURLConnection httpConn = null;
-        HttpsURLConnection httpsConn = null;
-        try {
-            URI uri = new URI(url);
-            if (uri.getScheme().equalsIgnoreCase("http")) {
+    public static long getRemoteSize(String url) {
+        long remoteSize = 0L;
+        final String[] methods = new String[]{"HEAD", "GET"};
+        IllegalArgumentException exception = null;
+        // Attempting first a HEAD request to avoid downloading the whole file. If
+        // it fails (for example with S3 presigned URL), fallback on a standard GET
+        // request.
+        for (String method : methods) {
+            HttpURLConnection httpConn = null;
+            try {
+                URI uri = new URI(url);
                 httpConn = (HttpURLConnection)uri.toURL().openConnection();
-                if (httpConn != null) {
-                    httpConn.setConnectTimeout(2000);
-                    httpConn.setReadTimeout(5000);
-                    String contentLength = httpConn.getHeaderField("content-length");
-                    if (contentLength != null) {
-                        remoteSize = Long.parseLong(contentLength);
+                httpConn.setRequestMethod(method);
+                httpConn.setConnectTimeout(2000);
+                httpConn.setReadTimeout(5000);
+                String contentLength = httpConn.getHeaderField("Content-Length");
+                if (contentLength != null) {
+                    remoteSize = Long.parseLong(contentLength);
+                } else if (method.equals("GET") && httpConn.getResponseCode() < 300) {
+                    // Calculate the content size based on the input stream content
+                    byte[] buf = new byte[1024];
+                    int length;
+                    while ((length = httpConn.getInputStream().read(buf, 0, buf.length)) != -1) {
+                        remoteSize += length;
                     }
-                    httpConn.disconnect();
                 }
-            } else if (uri.getScheme().equalsIgnoreCase("https")) {
-                httpsConn = (HttpsURLConnection)uri.toURL().openConnection();
-                if (httpsConn != null) {
-                    String contentLength = httpsConn.getHeaderField("content-length");
-                    if (contentLength != null) {
-                        remoteSize = Long.parseLong(contentLength);
-                    }
-                    httpsConn.disconnect();
+                return remoteSize;
+            } catch (URISyntaxException e) {
+                throw new IllegalArgumentException("Invalid URL " + url);
+            } catch (IOException e) {
+                exception = new IllegalArgumentException("Unable to establish connection with URL " + url);
+            } finally {
+                if (httpConn != null) {
+                    httpConn.disconnect();
                 }
             }
-        } catch (URISyntaxException e) {
-            throw new IllegalArgumentException("Invalid URL " + url);
-        } catch (IOException e) {
-            throw new IllegalArgumentException("Unable to establish connection with URL " + url);
         }
-        return remoteSize;
+        if (exception != null) {
+            throw exception;
+        }
+        return 0L;
     }
 
     public static Pair<String, Integer> validateUrl(String url) throws IllegalArgumentException {