Add DigestAuthProvider

src/main/java/com/rohitawate/everest/auth/DigestAuthProvider.java

@@ -0,0 +1,95 @@
+package com.rohitawate.everest.auth;
+
+import javax.xml.bind.DatatypeConverter;
+import java.io.IOException;
+import java.net.HttpURLConnection;
+import java.net.URL;
+import java.security.MessageDigest;
+import java.security.NoSuchAlgorithmException;
+import java.util.regex.Matcher;
+import java.util.regex.Pattern;
+
+public class DigestAuthProvider implements AuthProvider {
+
+    private String url;
+    private final String method;
+    private String username;
+    private String password;
+    private boolean enabled;
+
+    private static MessageDigest digester;
+
+    static {
+        try {
+            digester = MessageDigest.getInstance("MD5");
+        } catch (NoSuchAlgorithmException e) {
+            e.printStackTrace();
+        }
+    }
+
+    public DigestAuthProvider(String url, String method, String username, String password, boolean enabled) {
+        this.url = url;
+        this.method = method;
+        this.username = username;
+        this.password = password;
+        this.enabled = enabled;
+    }
+
+    @Override
+    public String getAuthHeader() {
+        StringBuilder header = new StringBuilder();
+        header.append("Digest ");
+
+        try {
+            URL digestURL = new URL(url);
+            HttpURLConnection conn = (HttpURLConnection) digestURL.openConnection();
+            String nonceHeader = conn.getHeaderField("WWW-Authenticate");
+
+            Pattern digestPattern = Pattern.compile("(\\w+)[:=] ?\"?([^\" ,]+)\"?");
+            Matcher matcher = digestPattern.matcher(nonceHeader);
+
+            String realm = null;
+            String nonce = null;
+            while (matcher.find()) {
+                switch (matcher.group(1)) {
+                    case "realm":
+                        realm = matcher.group(2);
+                        break;
+                    case "nonce":
+                        nonce = matcher.group(2);
+                        break;
+                }
+            }
+
+            String ha1 = getMD5Hash(username + ":" + realm + ":" + password);
+            String ha2 = getMD5Hash(method + ":" + digestURL.getPath());
+            String response = getMD5Hash(ha1 + ":" + nonce + ":" + ha2);
+
+            header.append("username=\"");
+            header.append(username);
+            header.append("\", realm=\"");
+            header.append(realm);
+            header.append("\", nonce=\"");
+            header.append(nonce);
+            header.append("\", uri=\"");
+            header.append(digestURL.getPath());
+            header.append("\", response=\"");
+            header.append(response);
+            header.append("\"");
+        } catch (IOException e) {
+            e.printStackTrace();
+        }
+
+        return header.toString();
+    }
+
+    @Override
+    public boolean isEnabled() {
+        return enabled;
+    }
+
+    private static String getMD5Hash(String input) {
+        digester.update(input.getBytes());
+        return DatatypeConverter.printHexBinary(digester.digest()).toLowerCase();
+    }
+}

test/com/rohitawate/everest/auth/DigestAuthProviderTest.java

@@ -0,0 +1,14 @@
+package com.rohitawate.everest.auth;
+
+import org.junit.jupiter.api.Test;
+
+import static org.junit.jupiter.api.Assertions.*;
+
+class DigestAuthProviderTest {
+
+    @Test
+    void getAuthHeader() {
+        DigestAuthProvider provider = new DigestAuthProvider("https://jigsaw.w3.org/HTTP/Digest/", "GET", "guest", "guest", false);
+        System.out.println(provider.getAuthHeader());
+    }
+}