|
| 1 | +package info.unterrainer.websocketserver; |
| 2 | + |
| 3 | +import java.io.IOException; |
| 4 | +import java.math.BigInteger; |
| 5 | +import java.net.URI; |
| 6 | +import java.net.http.HttpClient; |
| 7 | +import java.net.http.HttpRequest; |
| 8 | +import java.net.http.HttpResponse; |
| 9 | +import java.security.KeyFactory; |
| 10 | +import java.security.PublicKey; |
| 11 | +import java.security.spec.RSAPublicKeySpec; |
| 12 | +import java.util.Base64; |
| 13 | + |
| 14 | +import org.keycloak.TokenVerifier; |
| 15 | +import org.keycloak.common.VerificationException; |
| 16 | +import org.keycloak.representations.AccessToken; |
| 17 | + |
| 18 | +import com.fasterxml.jackson.databind.JsonNode; |
| 19 | +import com.fasterxml.jackson.databind.ObjectMapper; |
| 20 | + |
| 21 | +import info.unterrainer.commons.httpserver.exceptions.ForbiddenException; |
| 22 | +import info.unterrainer.commons.httpserver.exceptions.UnauthorizedException; |
| 23 | +import lombok.RequiredArgsConstructor; |
| 24 | +import lombok.extern.slf4j.Slf4j; |
| 25 | + |
| 26 | +@Slf4j |
| 27 | +@RequiredArgsConstructor |
| 28 | +public class JwtTokenHandler { |
| 29 | + |
| 30 | + private final String host; |
| 31 | + private final String realm; |
| 32 | + |
| 33 | + private String authUrl; |
| 34 | + private PublicKey publicKey = null; |
| 35 | + |
| 36 | + public void initPublicKey() { |
| 37 | + String correctedHost = host; |
| 38 | + String correctedRealm = realm; |
| 39 | + |
| 40 | + if (publicKey != null) |
| 41 | + return; |
| 42 | + if (!correctedHost.endsWith("/")) |
| 43 | + correctedHost += "/"; |
| 44 | + if (!correctedRealm.startsWith("/")) |
| 45 | + correctedRealm = "/" + correctedRealm; |
| 46 | + |
| 47 | + authUrl = correctedHost + "realms" + correctedRealm + "/protocol/openid-connect/certs"; |
| 48 | + try { |
| 49 | + log.info("Getting public key from: [{}]", authUrl); |
| 50 | + publicKey = fetchPublicKey(authUrl); |
| 51 | + } catch (Exception e) { |
| 52 | + log.error("There was an error fetching the PublicKey from the openIdConnect-server [{}].", authUrl); |
| 53 | + throw new IllegalStateException(e); |
| 54 | + } |
| 55 | + } |
| 56 | + |
| 57 | + private PublicKey fetchPublicKey(String jwksUrl) throws Exception { |
| 58 | + ObjectMapper objectMapper = new ObjectMapper(); |
| 59 | + HttpClient client = HttpClient.newHttpClient(); |
| 60 | + HttpRequest request = HttpRequest.newBuilder().uri(URI.create(jwksUrl)).GET().build(); |
| 61 | + |
| 62 | + HttpResponse<String> response = client.send(request, HttpResponse.BodyHandlers.ofString()); |
| 63 | + |
| 64 | + if (response.statusCode() >= 300) { |
| 65 | + throw new IOException("Failed to fetch JWKS: HTTP " + response.statusCode()); |
| 66 | + } |
| 67 | + |
| 68 | + JsonNode jwks = objectMapper.readTree(response.body()); |
| 69 | + // Just take the first key for now. |
| 70 | + JsonNode key = jwks.get("keys").get(0); |
| 71 | + |
| 72 | + String modulusBase64 = key.get("n").asText(); |
| 73 | + String exponentBase64 = key.get("e").asText(); |
| 74 | + |
| 75 | + byte[] modulusBytes = Base64.getUrlDecoder().decode(modulusBase64); |
| 76 | + byte[] exponentBytes = Base64.getUrlDecoder().decode(exponentBase64); |
| 77 | + |
| 78 | + BigInteger modulus = new BigInteger(1, modulusBytes); |
| 79 | + BigInteger exponent = new BigInteger(1, exponentBytes); |
| 80 | + |
| 81 | + RSAPublicKeySpec spec = new RSAPublicKeySpec(modulus, exponent); |
| 82 | + KeyFactory factory = KeyFactory.getInstance("RSA"); |
| 83 | + return factory.generatePublic(spec); |
| 84 | + } |
| 85 | + |
| 86 | + public void checkAccess(String authorizationHeader) { |
| 87 | + try { |
| 88 | + TokenVerifier<AccessToken> tokenVerifier = persistUserInfoInContext(authorizationHeader); |
| 89 | + if (tokenVerifier == null) |
| 90 | + throw new UnauthorizedException(); |
| 91 | + |
| 92 | + initPublicKey(); |
| 93 | + tokenVerifier.publicKey(publicKey); |
| 94 | + try { |
| 95 | + tokenVerifier.verifySignature(); |
| 96 | + } catch (VerificationException e) { |
| 97 | + throw new UnauthorizedException( |
| 98 | + "Error verifying token from user with publicKey obtained from keycloak.", e); |
| 99 | + } |
| 100 | + |
| 101 | + try { |
| 102 | + tokenVerifier.verify(); |
| 103 | + throw new ForbiddenException(); |
| 104 | + } catch (VerificationException e) { |
| 105 | + throw new ForbiddenException(); |
| 106 | + } |
| 107 | + } catch (Exception e) { |
| 108 | + log.error("Error checking token.", e); |
| 109 | + throw e; |
| 110 | + } |
| 111 | + } |
| 112 | + |
| 113 | + private TokenVerifier<AccessToken> persistUserInfoInContext(String authorizationHeader) { |
| 114 | + if (authorizationHeader == null || authorizationHeader.isBlank()) |
| 115 | + return null; |
| 116 | + |
| 117 | + try { |
| 118 | + TokenVerifier<AccessToken> tokenVerifier = TokenVerifier.create(authorizationHeader, AccessToken.class); |
| 119 | + AccessToken token = tokenVerifier.getToken(); |
| 120 | + if (!token.isActive()) { |
| 121 | + log.warn("Token is inactive."); |
| 122 | + return null; |
| 123 | + } |
| 124 | + // Disabled to enable getting token from side-channels like 'localhost'. |
| 125 | + /* |
| 126 | + * if (!token.getIssuer().equalsIgnoreCase(authUrl)) { |
| 127 | + * setTokenRejectionReason(ctx, "Token has wrong real-url."); return null; } |
| 128 | + */ |
| 129 | + return tokenVerifier; |
| 130 | + |
| 131 | + } catch (VerificationException e) { |
| 132 | + log.warn("Token was checked and deemed invalid.", e); |
| 133 | + return null; |
| 134 | + } |
| 135 | + } |
| 136 | +} |
0 commit comments