michael@0: /* This Source Code Form is subject to the terms of the Mozilla Public
michael@0:  * License, v. 2.0. If a copy of the MPL was not distributed with this
michael@0:  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
michael@0: 
michael@0: package org.mozilla.gecko.sync.net;
michael@0: 
michael@0: import java.io.IOException;
michael@0: import java.io.InputStream;
michael@0: import java.io.UnsupportedEncodingException;
michael@0: import java.net.URI;
michael@0: import java.security.GeneralSecurityException;
michael@0: import java.security.InvalidKeyException;
michael@0: import java.security.MessageDigest;
michael@0: import java.security.NoSuchAlgorithmException;
michael@0: import java.util.Locale;
michael@0: 
michael@0: import javax.crypto.Mac;
michael@0: import javax.crypto.spec.SecretKeySpec;
michael@0: 
michael@0: import org.mozilla.apache.commons.codec.binary.Base64;
michael@0: import org.mozilla.gecko.background.common.log.Logger;
michael@0: import org.mozilla.gecko.sync.Utils;
michael@0: 
michael@0: import ch.boye.httpclientandroidlib.Header;
michael@0: import ch.boye.httpclientandroidlib.HttpEntity;
michael@0: import ch.boye.httpclientandroidlib.HttpEntityEnclosingRequest;
michael@0: import ch.boye.httpclientandroidlib.client.methods.HttpRequestBase;
michael@0: import ch.boye.httpclientandroidlib.client.methods.HttpUriRequest;
michael@0: import ch.boye.httpclientandroidlib.impl.client.DefaultHttpClient;
michael@0: import ch.boye.httpclientandroidlib.message.BasicHeader;
michael@0: import ch.boye.httpclientandroidlib.protocol.BasicHttpContext;
michael@0: 
michael@0: /**
michael@0:  * An <code>AuthHeaderProvider</code> that returns an Authorization header for
michael@0:  * Hawk: <a href="https://github.com/hueniverse/hawk">https://github.com/hueniverse/hawk</a>.
michael@0:  *
michael@0:  * Hawk is an HTTP authentication scheme using a message authentication code
michael@0:  * (MAC) algorithm to provide partial HTTP request cryptographic verification.
michael@0:  * Hawk is the successor to the HMAC authentication scheme.
michael@0:  */
michael@0: public class HawkAuthHeaderProvider implements AuthHeaderProvider {
michael@0:   public static final String LOG_TAG = HawkAuthHeaderProvider.class.getSimpleName();
michael@0: 
michael@0:   public static final int HAWK_HEADER_VERSION = 1;
michael@0: 
michael@0:   protected static final int NONCE_LENGTH_IN_BYTES = 8;
michael@0:   protected static final String HMAC_SHA256_ALGORITHM = "hmacSHA256";
michael@0: 
michael@0:   protected final String id;
michael@0:   protected final byte[] key;
michael@0:   protected final boolean includePayloadHash;
michael@0:   protected final long skewSeconds;
michael@0: 
michael@0:   /**
michael@0:    * Create a Hawk Authorization header provider.
michael@0:    * <p>
michael@0:    * Hawk specifies no mechanism by which a client receives an
michael@0:    * identifier-and-key pair from the server.
michael@0:    * <p>
michael@0:    * Hawk requests can include a payload verification hash with requests that
michael@0:    * enclose an entity (PATCH, POST, and PUT requests).  <b>You should default
michael@0:    * to including the payload verification hash<b> unless you have a good reason
michael@0:    * not to -- the server can always ignore payload verification hashes provided
michael@0:    * by the client.
michael@0:    *
michael@0:    * @param id
michael@0:    *          to name requests with.
michael@0:    * @param key
michael@0:    *          to sign request with.
michael@0:    *
michael@0:    * @param includePayloadHash
michael@0:    *          true if payload verification hash should be included in signed
michael@0:    *          request header. See <a href="https://github.com/hueniverse/hawk#payload-validation">https://github.com/hueniverse/hawk#payload-validation</a>.
michael@0:    *
michael@0:    * @param skewSeconds
michael@0:    *          a number of seconds by which to skew the current time when
michael@0:    *          computing a header.
michael@0:    */
michael@0:   public HawkAuthHeaderProvider(String id, byte[] key, boolean includePayloadHash, long skewSeconds) {
michael@0:     if (id == null) {
michael@0:       throw new IllegalArgumentException("id must not be null");
michael@0:     }
michael@0:     if (key == null) {
michael@0:       throw new IllegalArgumentException("key must not be null");
michael@0:     }
michael@0:     this.id = id;
michael@0:     this.key = key;
michael@0:     this.includePayloadHash = includePayloadHash;
michael@0:     this.skewSeconds = skewSeconds;
michael@0:   }
michael@0: 
michael@0:   /**
michael@0:    * @return the current time in milliseconds.
michael@0:    */
michael@0:   @SuppressWarnings("static-method")
michael@0:   protected long now() {
michael@0:     return System.currentTimeMillis();
michael@0:   }
michael@0: 
michael@0:   /**
michael@0:    * @return the current time in seconds, adjusted for skew. This should
michael@0:    *         approximate the server's timestamp.
michael@0:    */
michael@0:   protected long getTimestampSeconds() {
michael@0:     return (now() / 1000) + skewSeconds;
michael@0:   }
michael@0: 
michael@0:   @Override
michael@0:   public Header getAuthHeader(HttpRequestBase request, BasicHttpContext context, DefaultHttpClient client) throws GeneralSecurityException {
michael@0:     long timestamp = getTimestampSeconds();
michael@0:     String nonce = Base64.encodeBase64String(Utils.generateRandomBytes(NONCE_LENGTH_IN_BYTES));
michael@0:     String extra = "";
michael@0: 
michael@0:     try {
michael@0:       return getAuthHeader(request, context, client, timestamp, nonce, extra, this.includePayloadHash);
michael@0:     } catch (Exception e) {
michael@0:       // We lie a little and make every exception a GeneralSecurityException.
michael@0:       throw new GeneralSecurityException(e);
michael@0:     }
michael@0:   }
michael@0: 
michael@0:   /**
michael@0:    * Helper function that generates an HTTP Authorization: Hawk header given
michael@0:    * additional Hawk specific data.
michael@0:    *
michael@0:    * @throws NoSuchAlgorithmException
michael@0:    * @throws InvalidKeyException
michael@0:    * @throws IOException
michael@0:    */
michael@0:   protected Header getAuthHeader(HttpRequestBase request, BasicHttpContext context, DefaultHttpClient client,
michael@0:       long timestamp, String nonce, String extra, boolean includePayloadHash)
michael@0:           throws InvalidKeyException, NoSuchAlgorithmException, IOException {
michael@0:     if (timestamp < 0) {
michael@0:       throw new IllegalArgumentException("timestamp must contain only [0-9].");
michael@0:     }
michael@0: 
michael@0:     if (nonce == null) {
michael@0:       throw new IllegalArgumentException("nonce must not be null.");
michael@0:     }
michael@0:     if (nonce.length() == 0) {
michael@0:       throw new IllegalArgumentException("nonce must not be empty.");
michael@0:     }
michael@0: 
michael@0:     String payloadHash = null;
michael@0:     if (includePayloadHash) {
michael@0:       payloadHash = getPayloadHashString(request);
michael@0:     } else {
michael@0:       Logger.debug(LOG_TAG, "Configured to not include payload hash for this request.");
michael@0:     }
michael@0: 
michael@0:     String app = null;
michael@0:     String dlg = null;
michael@0:     String requestString = getRequestString(request, "header", timestamp, nonce, payloadHash, extra, app, dlg);
michael@0:     String macString = getSignature(requestString.getBytes("UTF-8"), this.key);
michael@0: 
michael@0:     StringBuilder sb = new StringBuilder();
michael@0:     sb.append("Hawk id=\"");
michael@0:     sb.append(this.id);
michael@0:     sb.append("\", ");
michael@0:     sb.append("ts=\"");
michael@0:     sb.append(timestamp);
michael@0:     sb.append("\", ");
michael@0:     sb.append("nonce=\"");
michael@0:     sb.append(nonce);
michael@0:     sb.append("\", ");
michael@0:     if (payloadHash != null) {
michael@0:       sb.append("hash=\"");
michael@0:       sb.append(payloadHash);
michael@0:       sb.append("\", ");
michael@0:     }
michael@0:     if (extra != null && extra.length() > 0) {
michael@0:       sb.append("ext=\"");
michael@0:       sb.append(escapeExtraHeaderAttribute(extra));
michael@0:       sb.append("\", ");
michael@0:     }
michael@0:     sb.append("mac=\"");
michael@0:     sb.append(macString);
michael@0:     sb.append("\"");
michael@0: 
michael@0:     return new BasicHeader("Authorization", sb.toString());
michael@0:   }
michael@0: 
michael@0:   /**
michael@0:    * Get the payload verification hash for the given request, if possible.
michael@0:    * <p>
michael@0:    * Returns null if the request does not enclose an entity (is not an HTTP
michael@0:    * PATCH, POST, or PUT). Throws if the payload verification hash cannot be
michael@0:    * computed.
michael@0:    *
michael@0:    * @param request
michael@0:    *          to compute hash for.
michael@0:    * @return verification hash, or null if the request does not enclose an entity.
michael@0:    * @throws IllegalArgumentException if the request does not enclose a valid non-null entity.
michael@0:    * @throws UnsupportedEncodingException
michael@0:    * @throws NoSuchAlgorithmException
michael@0:    * @throws IOException
michael@0:    */
michael@0:   protected static String getPayloadHashString(HttpRequestBase request)
michael@0:       throws UnsupportedEncodingException, NoSuchAlgorithmException, IOException, IllegalArgumentException {
michael@0:     final boolean shouldComputePayloadHash = request instanceof HttpEntityEnclosingRequest;
michael@0:     if (!shouldComputePayloadHash) {
michael@0:       Logger.debug(LOG_TAG, "Not computing payload verification hash for non-enclosing request.");
michael@0:       return null;
michael@0:     }
michael@0:     if (!(request instanceof HttpEntityEnclosingRequest)) {
michael@0:       throw new IllegalArgumentException("Cannot compute payload verification hash for enclosing request without an entity");
michael@0:     }
michael@0:     final HttpEntity entity = ((HttpEntityEnclosingRequest) request).getEntity();
michael@0:     if (entity == null) {
michael@0:       throw new IllegalArgumentException("Cannot compute payload verification hash for enclosing request with a null entity");
michael@0:     }
michael@0:     return Base64.encodeBase64String(getPayloadHash(entity));
michael@0:   }
michael@0: 
michael@0:   /**
michael@0:    * Escape the user-provided extra string for the ext="" header attribute.
michael@0:    * <p>
michael@0:    * Hawk escapes the header ext="" attribute differently than it does the extra
michael@0:    * line in the normalized request string.
michael@0:    * <p>
michael@0:    * See <a href="https://github.com/hueniverse/hawk/blob/871cc597973110900467bd3dfb84a3c892f678fb/lib/browser.js#L385">https://github.com/hueniverse/hawk/blob/871cc597973110900467bd3dfb84a3c892f678fb/lib/browser.js#L385</a>.
michael@0:    *
michael@0:    * @param extra to escape.
michael@0:    * @return extra escaped for the ext="" header attribute.
michael@0:    */
michael@0:   protected static String escapeExtraHeaderAttribute(String extra) {
michael@0:     return extra.replaceAll("\\\\", "\\\\").replaceAll("\"", "\\\"");
michael@0:   }
michael@0: 
michael@0:   /**
michael@0:    * Escape the user-provided extra string for inserting into the normalized
michael@0:    * request string.
michael@0:    * <p>
michael@0:    * Hawk escapes the header ext="" attribute differently than it does the extra
michael@0:    * line in the normalized request string.
michael@0:    * <p>
michael@0:    * See <a href="https://github.com/hueniverse/hawk/blob/871cc597973110900467bd3dfb84a3c892f678fb/lib/crypto.js#L67">https://github.com/hueniverse/hawk/blob/871cc597973110900467bd3dfb84a3c892f678fb/lib/crypto.js#L67</a>.
michael@0:    *
michael@0:    * @param extra to escape.
michael@0:    * @return extra escaped for the normalized request string.
michael@0:    */
michael@0:   protected static String escapeExtraString(String extra) {
michael@0:     return extra.replaceAll("\\\\", "\\\\").replaceAll("\n", "\\n");
michael@0:   }
michael@0: 
michael@0:   /**
michael@0:    * Return the content type with no parameters (pieces following ;).
michael@0:    *
michael@0:    * @param contentTypeHeader to interrogate.
michael@0:    * @return base content type.
michael@0:    */
michael@0:   protected static String getBaseContentType(Header contentTypeHeader) {
michael@0:     if (contentTypeHeader == null) {
michael@0:       throw new IllegalArgumentException("contentTypeHeader must not be null.");
michael@0:     }
michael@0:     String contentType = contentTypeHeader.getValue();
michael@0:     if (contentType == null) {
michael@0:       throw new IllegalArgumentException("contentTypeHeader value must not be null.");
michael@0:     }
michael@0:     int index = contentType.indexOf(";");
michael@0:     if (index < 0) {
michael@0:       return contentType.trim();
michael@0:     }
michael@0:     return contentType.substring(0, index).trim();
michael@0:   }
michael@0: 
michael@0:   /**
michael@0:    * Generate the SHA-256 hash of a normalized Hawk payload generated from an
michael@0:    * HTTP entity.
michael@0:    * <p>
michael@0:    * <b>Warning:</b> the entity <b>must</b> be repeatable.  If it is not, this
michael@0:    * code throws an <code>IllegalArgumentException</code>.
michael@0:    * <p>
michael@0:    * This is under-specified; the code here was reverse engineered from the code
michael@0:    * at
michael@0:    * <a href="https://github.com/hueniverse/hawk/blob/871cc597973110900467bd3dfb84a3c892f678fb/lib/crypto.js#L81">https://github.com/hueniverse/hawk/blob/871cc597973110900467bd3dfb84a3c892f678fb/lib/crypto.js#L81</a>.
michael@0:    * @param entity to normalize and hash.
michael@0:    * @return hash.
michael@0:    * @throws IllegalArgumentException if entity is not repeatable.
michael@0:    */
michael@0:   protected static byte[] getPayloadHash(HttpEntity entity) throws UnsupportedEncodingException, IOException, NoSuchAlgorithmException {
michael@0:     if (!entity.isRepeatable()) {
michael@0:       throw new IllegalArgumentException("entity must be repeatable");
michael@0:     }
michael@0:     final MessageDigest digest = MessageDigest.getInstance("SHA-256");
michael@0:     digest.update(("hawk." + HAWK_HEADER_VERSION + ".payload\n").getBytes("UTF-8"));
michael@0:     digest.update(getBaseContentType(entity.getContentType()).getBytes("UTF-8"));
michael@0:     digest.update("\n".getBytes("UTF-8"));
michael@0:     InputStream stream = entity.getContent();
michael@0:     try {
michael@0:       int numRead;
michael@0:       byte[] buffer = new byte[4096];
michael@0:       while (-1 != (numRead = stream.read(buffer))) {
michael@0:         if (numRead > 0) {
michael@0:           digest.update(buffer, 0, numRead);
michael@0:         }
michael@0:       }
michael@0:       digest.update("\n".getBytes("UTF-8")); // Trailing newline is specified by Hawk.
michael@0:       return digest.digest();
michael@0:     } finally {
michael@0:       stream.close();
michael@0:     }
michael@0:   }
michael@0: 
michael@0:   /**
michael@0:    * Generate a normalized Hawk request string. This is under-specified; the
michael@0:    * code here was reverse engineered from the code at
michael@0:    * <a href="https://github.com/hueniverse/hawk/blob/871cc597973110900467bd3dfb84a3c892f678fb/lib/crypto.js#L55">https://github.com/hueniverse/hawk/blob/871cc597973110900467bd3dfb84a3c892f678fb/lib/crypto.js#L55</a>.
michael@0:    * <p>
michael@0:    * This method trusts its inputs to be valid.
michael@0:    */
michael@0:   protected static String getRequestString(HttpUriRequest request, String type, long timestamp, String nonce, String hash, String extra, String app, String dlg) {
michael@0:     String method = request.getMethod().toUpperCase(Locale.US);
michael@0: 
michael@0:     URI uri = request.getURI();
michael@0:     String host = uri.getHost();
michael@0: 
michael@0:     String path = uri.getRawPath();
michael@0:     if (uri.getRawQuery() != null) {
michael@0:       path += "?";
michael@0:       path += uri.getRawQuery();
michael@0:     }
michael@0:     if (uri.getRawFragment() != null) {
michael@0:       path += "#";
michael@0:       path += uri.getRawFragment();
michael@0:     }
michael@0: 
michael@0:     int port = uri.getPort();
michael@0:     String scheme = uri.getScheme();
michael@0:     if (port != -1) {
michael@0:     } else if ("http".equalsIgnoreCase(scheme)) {
michael@0:       port = 80;
michael@0:     } else if ("https".equalsIgnoreCase(scheme)) {
michael@0:       port = 443;
michael@0:     } else {
michael@0:       throw new IllegalArgumentException("Unsupported URI scheme: " + scheme + ".");
michael@0:     }
michael@0: 
michael@0:     StringBuilder sb = new StringBuilder();
michael@0:     sb.append("hawk.");
michael@0:     sb.append(HAWK_HEADER_VERSION);
michael@0:     sb.append('.');
michael@0:     sb.append(type);
michael@0:     sb.append('\n');
michael@0:     sb.append(timestamp);
michael@0:     sb.append('\n');
michael@0:     sb.append(nonce);
michael@0:     sb.append('\n');
michael@0:     sb.append(method);
michael@0:     sb.append('\n');
michael@0:     sb.append(path);
michael@0:     sb.append('\n');
michael@0:     sb.append(host);
michael@0:     sb.append('\n');
michael@0:     sb.append(port);
michael@0:     sb.append('\n');
michael@0:     if (hash != null) {
michael@0:       sb.append(hash);
michael@0:     }
michael@0:     sb.append("\n");
michael@0:     if (extra != null && extra.length() > 0) {
michael@0:       sb.append(escapeExtraString(extra));
michael@0:     }
michael@0:     sb.append("\n");
michael@0:     if (app != null) {
michael@0:       sb.append(app);
michael@0:       sb.append("\n");
michael@0:       if (dlg != null) {
michael@0:         sb.append(dlg);
michael@0:       }
michael@0:       sb.append("\n");
michael@0:     }
michael@0: 
michael@0:     return sb.toString();
michael@0:   }
michael@0: 
michael@0:   protected static byte[] hmacSha256(byte[] message, byte[] key)
michael@0:       throws NoSuchAlgorithmException, InvalidKeyException {
michael@0: 
michael@0:     SecretKeySpec keySpec = new SecretKeySpec(key, HMAC_SHA256_ALGORITHM);
michael@0: 
michael@0:     Mac hasher = Mac.getInstance(HMAC_SHA256_ALGORITHM);
michael@0:     hasher.init(keySpec);
michael@0:     hasher.update(message);
michael@0: 
michael@0:     return hasher.doFinal();
michael@0:   }
michael@0: 
michael@0:   /**
michael@0:    * Sign a Hawk request string.
michael@0:    *
michael@0:    * @param requestString to sign.
michael@0:    * @param key as <code>String</code>.
michael@0:    * @return signature as base-64 encoded string.
michael@0:    * @throws InvalidKeyException
michael@0:    * @throws NoSuchAlgorithmException
michael@0:    * @throws UnsupportedEncodingException
michael@0:    */
michael@0:   protected static String getSignature(byte[] requestString, byte[] key)
michael@0:       throws InvalidKeyException, NoSuchAlgorithmException, UnsupportedEncodingException {
michael@0:     return Base64.encodeBase64String(hmacSha256(requestString, key));
michael@0:   }
michael@0: }