SignerV4.java

/*
 * Copyright (C) 2015, Matthias Sohn <matthias.sohn@sap.com>
 * Copyright (C) 2015, Sasa Zivkov <sasa.zivkov@sap.com> and others
 *
 * This program and the accompanying materials are made available under the
 * terms of the Eclipse Distribution License v. 1.0 which is available at
 * https://www.eclipse.org/org/documents/edl-v10.php.
 *
 * SPDX-License-Identifier: BSD-3-Clause
 */
package org.eclipse.jgit.lfs.server.s3;

import static java.nio.charset.StandardCharsets.UTF_8;
import static org.eclipse.jgit.util.HttpSupport.HDR_AUTHORIZATION;

import java.io.UnsupportedEncodingException;
import java.net.URL;
import java.net.URLEncoder;
import java.security.MessageDigest;
import java.text.MessageFormat;
import java.text.SimpleDateFormat;
import java.util.ArrayList;
import java.util.Collections;
import java.util.Date;
import java.util.Iterator;
import java.util.List;
import java.util.Locale;
import java.util.Map;
import java.util.SimpleTimeZone;
import java.util.SortedMap;
import java.util.TreeMap;

import javax.crypto.Mac;
import javax.crypto.spec.SecretKeySpec;

import org.eclipse.jgit.lfs.lib.Constants;
import org.eclipse.jgit.lfs.server.internal.LfsServerText;

/**
 * Signing support for Amazon AWS signing V4
 * <p>
 * See
 * http://docs.aws.amazon.com/AmazonS3/latest/API/sig-v4-authenticating-requests.html
 */
class SignerV4 {
    static final String UNSIGNED_PAYLOAD = "UNSIGNED-PAYLOAD"; //$NON-NLS-1$

    private static final String ALGORITHM = "HMAC-SHA256"; //$NON-NLS-1$
    private static final String DATE_STRING_FORMAT = "yyyyMMdd"; //$NON-NLS-1$
    private static final String HEX = "0123456789abcdef"; //$NON-NLS-1$
    private static final String HMACSHA256 = "HmacSHA256"; //$NON-NLS-1$
    private static final String ISO8601_BASIC_FORMAT = "yyyyMMdd'T'HHmmss'Z'"; //$NON-NLS-1$
    private static final String S3 = "s3"; //$NON-NLS-1$
    private static final String SCHEME = "AWS4"; //$NON-NLS-1$
    private static final String TERMINATOR = "aws4_request"; //$NON-NLS-1$
    private static final String UTC = "UTC"; //$NON-NLS-1$
    private static final String X_AMZ_ALGORITHM = "X-Amz-Algorithm"; //$NON-NLS-1$
    private static final String X_AMZ_CREDENTIAL = "X-Amz-Credential"; //$NON-NLS-1$
    private static final String X_AMZ_DATE = "X-Amz-Date"; //$NON-NLS-1$
    private static final String X_AMZ_SIGNATURE = "X-Amz-Signature"; //$NON-NLS-1$
    private static final String X_AMZ_SIGNED_HEADERS = "X-Amz-SignedHeaders"; //$NON-NLS-1$

    static final String X_AMZ_CONTENT_SHA256 = "x-amz-content-sha256"; //$NON-NLS-1$
    static final String X_AMZ_EXPIRES = "X-Amz-Expires"; //$NON-NLS-1$
    static final String X_AMZ_STORAGE_CLASS = "x-amz-storage-class"; //$NON-NLS-1$

    /**
     * Create an AWSV4 authorization for a request, suitable for embedding in
     * query parameters.
     *
     * @param bucketConfig
     *            configuration of S3 storage bucket this request should be
     *            signed for
     * @param url
     *            HTTP request URL
     * @param httpMethod
     *            HTTP method
     * @param headers
     *            The HTTP request headers; 'Host' and 'X-Amz-Date' will be
     *            added to this set.
     * @param queryParameters
     *            Any query parameters that will be added to the endpoint. The
     *            parameters should be specified in canonical format.
     * @param bodyHash
     *            Pre-computed SHA256 hash of the request body content; this
     *            value should also be set as the header 'X-Amz-Content-SHA256'
     *            for non-streaming uploads.
     * @return The computed authorization string for the request. This value
     *         needs to be set as the header 'Authorization' on the subsequent
     *         HTTP request.
     */
    static String createAuthorizationQuery(S3Config bucketConfig, URL url,
            String httpMethod, Map<String, String> headers,
            Map<String, String> queryParameters, String bodyHash) {
        addHostHeader(url, headers);

        queryParameters.put(X_AMZ_ALGORITHM, SCHEME + "-" + ALGORITHM); //$NON-NLS-1$

        Date now = new Date();
        String dateStamp = dateStamp(now);
        String scope = scope(bucketConfig.getRegion(), dateStamp);
        queryParameters.put(X_AMZ_CREDENTIAL,
                bucketConfig.getAccessKey() + "/" + scope); //$NON-NLS-1$

        String dateTimeStampISO8601 = dateTimeStampISO8601(now);
        queryParameters.put(X_AMZ_DATE, dateTimeStampISO8601);

        String canonicalizedHeaderNames = canonicalizeHeaderNames(headers);
        queryParameters.put(X_AMZ_SIGNED_HEADERS, canonicalizedHeaderNames);

        String canonicalizedQueryParameters = canonicalizeQueryString(
                queryParameters);
        String canonicalizedHeaders = canonicalizeHeaderString(headers);
        String canonicalRequest = canonicalRequest(url, httpMethod,
                canonicalizedQueryParameters, canonicalizedHeaderNames,
                canonicalizedHeaders, bodyHash);
        byte[] signature = createSignature(bucketConfig, dateTimeStampISO8601,
                dateStamp, scope, canonicalRequest);
        queryParameters.put(X_AMZ_SIGNATURE, toHex(signature));

        return formatAuthorizationQuery(queryParameters);
    }

    private static String formatAuthorizationQuery(
            Map<String, String> queryParameters) {
        StringBuilder s = new StringBuilder();
        for (String key : queryParameters.keySet()) {
            appendQuery(s, key, queryParameters.get(key));
        }
        return s.toString();
    }

    private static void appendQuery(StringBuilder s, String key,
            String value) {
        if (s.length() != 0) {
            s.append("&"); //$NON-NLS-1$
        }
        s.append(key).append("=").append(value); //$NON-NLS-1$
    }

    /**
     * Sign headers for given bucket, url and HTTP method and add signature in
     * Authorization header.
     *
     * @param bucketConfig
     *            configuration of S3 storage bucket this request should be
     *            signed for
     * @param url
     *            HTTP request URL
     * @param httpMethod
     *            HTTP method
     * @param headers
     *            HTTP headers to sign
     * @param bodyHash
     *            Pre-computed SHA256 hash of the request body content; this
     *            value should also be set as the header 'X-Amz-Content-SHA256'
     *            for non-streaming uploads.
     * @return HTTP headers signd by an Authorization header added to the
     *         headers
     */
    static Map<String, String> createHeaderAuthorization(
            S3Config bucketConfig, URL url, String httpMethod,
            Map<String, String> headers, String bodyHash) {
        addHostHeader(url, headers);

        Date now = new Date();
        String dateTimeStamp = dateTimeStampISO8601(now);
        headers.put(X_AMZ_DATE, dateTimeStamp);

        String canonicalizedHeaderNames = canonicalizeHeaderNames(headers);
        String canonicalizedHeaders = canonicalizeHeaderString(headers);
        String canonicalRequest = canonicalRequest(url, httpMethod, "", //$NON-NLS-1$
                canonicalizedHeaderNames, canonicalizedHeaders, bodyHash);
        String dateStamp = dateStamp(now);
        String scope = scope(bucketConfig.getRegion(), dateStamp);

        byte[] signature = createSignature(bucketConfig, dateTimeStamp,
                dateStamp, scope, canonicalRequest);

        headers.put(HDR_AUTHORIZATION, formatAuthorizationHeader(bucketConfig,
                canonicalizedHeaderNames, scope, signature)); // $NON-NLS-1$

        return headers;
    }

    private static String formatAuthorizationHeader(
            S3Config bucketConfig, String canonicalizedHeaderNames,
            String scope, byte[] signature) {
        StringBuilder s = new StringBuilder();
        s.append(SCHEME).append("-").append(ALGORITHM).append(" "); //$NON-NLS-1$ //$NON-NLS-2$
        s.append("Credential=").append(bucketConfig.getAccessKey()).append("/") //$NON-NLS-1$//$NON-NLS-2$
                .append(scope).append(","); //$NON-NLS-1$
        s.append("SignedHeaders=").append(canonicalizedHeaderNames).append(","); //$NON-NLS-1$ //$NON-NLS-2$
        s.append("Signature=").append(toHex(signature)); //$NON-NLS-1$
        return s.toString();
    }

    private static void addHostHeader(URL url,
            Map<String, String> headers) {
        StringBuilder hostHeader = new StringBuilder(url.getHost());
        int port = url.getPort();
        if (port > -1) {
            hostHeader.append(":").append(port); //$NON-NLS-1$
        }
        headers.put("Host", hostHeader.toString()); //$NON-NLS-1$
    }

    private static String canonicalizeHeaderNames(
            Map<String, String> headers) {
        List<String> sortedHeaders = new ArrayList<>();
        sortedHeaders.addAll(headers.keySet());
        Collections.sort(sortedHeaders, String.CASE_INSENSITIVE_ORDER);

        StringBuilder buffer = new StringBuilder();
        for (String header : sortedHeaders) {
            if (buffer.length() > 0)
                buffer.append(";"); //$NON-NLS-1$
            buffer.append(header.toLowerCase(Locale.ROOT));
        }

        return buffer.toString();
    }

    private static String canonicalizeHeaderString(
            Map<String, String> headers) {
        if (headers == null || headers.isEmpty()) {
            return ""; //$NON-NLS-1$
        }

        List<String> sortedHeaders = new ArrayList<>();
        sortedHeaders.addAll(headers.keySet());
        Collections.sort(sortedHeaders, String.CASE_INSENSITIVE_ORDER);

        StringBuilder buffer = new StringBuilder();
        for (String key : sortedHeaders) {
            buffer.append(
                    key.toLowerCase(Locale.ROOT).replaceAll("\\s+", " ") + ":" //$NON-NLS-1$ //$NON-NLS-2$ //$NON-NLS-3$
                    + headers.get(key).replaceAll("\\s+", " ")); //$NON-NLS-1$//$NON-NLS-2$
            buffer.append("\n"); //$NON-NLS-1$
        }

        return buffer.toString();
    }

    private static String dateStamp(Date now) {
        // TODO(ms) cache and reuse DateFormat instances
        SimpleDateFormat dateStampFormat = new SimpleDateFormat(
                DATE_STRING_FORMAT);
        dateStampFormat.setTimeZone(new SimpleTimeZone(0, UTC));
        String dateStamp = dateStampFormat.format(now);
        return dateStamp;
    }

    private static String dateTimeStampISO8601(Date now) {
        // TODO(ms) cache and reuse DateFormat instances
        SimpleDateFormat dateTimeFormat = new SimpleDateFormat(
                ISO8601_BASIC_FORMAT);
        dateTimeFormat.setTimeZone(new SimpleTimeZone(0, UTC));
        String dateTimeStamp = dateTimeFormat.format(now);
        return dateTimeStamp;
    }

    private static String scope(String region, String dateStamp) {
        String scope = String.format("%s/%s/%s/%s", dateStamp, region, S3, //$NON-NLS-1$
                TERMINATOR);
        return scope;
    }

    private static String canonicalizeQueryString(
            Map<String, String> parameters) {
        if (parameters == null || parameters.isEmpty()) {
            return ""; //$NON-NLS-1$
        }

        SortedMap<String, String> sorted = new TreeMap<>();

        Iterator<Map.Entry<String, String>> pairs = parameters.entrySet()
                .iterator();
        while (pairs.hasNext()) {
            Map.Entry<String, String> pair = pairs.next();
            String key = pair.getKey();
            String value = pair.getValue();
            sorted.put(urlEncode(key, false), urlEncode(value, false));
        }

        StringBuilder builder = new StringBuilder();
        pairs = sorted.entrySet().iterator();
        while (pairs.hasNext()) {
            Map.Entry<String, String> pair = pairs.next();
            builder.append(pair.getKey());
            builder.append("="); //$NON-NLS-1$
            builder.append(pair.getValue());
            if (pairs.hasNext()) {
                builder.append("&"); //$NON-NLS-1$
            }
        }

        return builder.toString();
    }

    private static String canonicalRequest(URL endpoint, String httpMethod,
            String queryParameters, String canonicalizedHeaderNames,
            String canonicalizedHeaders, String bodyHash) {
        return String.format("%s\n%s\n%s\n%s\n%s\n%s", //$NON-NLS-1$
                httpMethod, canonicalizeResourcePath(endpoint),
                queryParameters, canonicalizedHeaders, canonicalizedHeaderNames,
                bodyHash);
    }

    private static String canonicalizeResourcePath(URL endpoint) {
        if (endpoint == null) {
            return "/"; //$NON-NLS-1$
        }
        String path = endpoint.getPath();
        if (path == null || path.isEmpty()) {
            return "/"; //$NON-NLS-1$
        }

        String encodedPath = urlEncode(path, true);
        if (encodedPath.startsWith("/")) { //$NON-NLS-1$
            return encodedPath;
        }
        return "/" + encodedPath; //$NON-NLS-1$
    }

    private static byte[] hash(String s) {
        MessageDigest md = Constants.newMessageDigest();
        md.update(s.getBytes(UTF_8));
        return md.digest();
    }

    private static byte[] sign(String stringData, byte[] key) {
        try {
            byte[] data = stringData.getBytes(UTF_8);
            Mac mac = Mac.getInstance(HMACSHA256);
            mac.init(new SecretKeySpec(key, HMACSHA256));
            return mac.doFinal(data);
        } catch (Exception e) {
            throw new RuntimeException(MessageFormat.format(
                    LfsServerText.get().failedToCalcSignature, e.getMessage()),
                    e);
        }
    }

    private static String stringToSign(String scheme, String algorithm,
            String dateTime, String scope, String canonicalRequest) {
        return String.format("%s-%s\n%s\n%s\n%s", //$NON-NLS-1$
                scheme, algorithm, dateTime, scope,
                toHex(hash(canonicalRequest)));
    }

    private static String toHex(byte[] bytes) {
        StringBuilder builder = new StringBuilder(2 * bytes.length);
        for (byte b : bytes) {
            builder.append(HEX.charAt((b & 0xF0) >> 4));
            builder.append(HEX.charAt(b & 0xF));
        }
        return builder.toString();
    }

    private static String urlEncode(String url, boolean keepPathSlash) {
        String encoded;
        try {
            encoded = URLEncoder.encode(url, UTF_8.name());
        } catch (UnsupportedEncodingException e) {
            throw new RuntimeException(LfsServerText.get().unsupportedUtf8, e);
        }
        if (keepPathSlash) {
            encoded = encoded.replace("%2F", "/"); //$NON-NLS-1$ //$NON-NLS-2$
        }
        return encoded;
    }

    private static byte[] createSignature(S3Config bucketConfig,
            String dateTimeStamp, String dateStamp,
            String scope, String canonicalRequest) {
        String stringToSign = stringToSign(SCHEME, ALGORITHM, dateTimeStamp,
                scope, canonicalRequest);

        byte[] signature = (SCHEME + bucketConfig.getSecretKey())
                .getBytes(UTF_8);
        signature = sign(dateStamp, signature);
        signature = sign(bucketConfig.getRegion(), signature);
        signature = sign(S3, signature);
        signature = sign(TERMINATOR, signature);
        signature = sign(stringToSign, signature);
        return signature;
    }
}