Example usage for com.fasterxml.jackson.core Base64Variants MODIFIED_FOR_URL

Introduction

In this page you can find the example usage for com.fasterxml.jackson.core Base64Variants MODIFIED_FOR_URL.

Prototype

Base64Variant MODIFIED_FOR_URL

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Document

This non-standard variant is usually used when encoded data needs to be passed via URLs (such as part of GET request).

Usage

From source file:me.lazerka.gae.jersey.oauth2.facebook.TokenVerifierFacebookSignedRequest.java

@Override
public FacebookUserPrincipal verify(String signedRequestToken) throws IOException, InvalidKeyException {
    logger.trace("Requesting endpoint to validate token");

    List<String> parts = Splitter.on('.').splitToList(signedRequestToken);

    checkArgument(parts.size() == 2, "Signed request must have two parts separated by period.");

    byte[] providedSignature = Base64Variants.MODIFIED_FOR_URL.decode(parts.get(0));
    String signedRequestJsonEncoded = parts.get(1);
    byte[] signedRequestJson = Base64Variants.MODIFIED_FOR_URL.decode(signedRequestJsonEncoded);

    SignedRequest signedRequest = jackson.readValue(signedRequestJson, SignedRequest.class);

    if (!"HMAC-SHA256".equals(signedRequest.algorithm)) {
        throw new InvalidKeyException("Unsupported signing method: " + signedRequest.algorithm);
    }// w w w  .j  a  v  a 2 s .c  o  m

    byte[] expectedSignature = hmac.doFinal(signedRequestJsonEncoded.getBytes(UTF_8));
    if (!Arrays.equals(providedSignature, expectedSignature)) {
        throw new InvalidKeyException("Signature invalid");
    }

    // We still need to verify expiration somehow. The only way is to ask Facebook.

    // Exchange `code` for long-lived access token.
    // This serves as verification for `code` expiration too.

    AccessTokenResponse response = fetcher.fetchUserAccessToken(signedRequest.code, redirectUri);

    // Not fetching email, because maybe we won't need to, if ID is enough.

    return new FacebookUserPrincipal(signedRequest.userId, null, response, null);
}

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