private String getStringToSign(MessageContext msgCtxt) throws Exception {
String msg = (String) this.properties.get("string-to-sign");
if (msg == null || msg.equals("")) {
// by default, get the content of the message (either request or response)
return msgCtxt.getVariable("message.content");
}
// replace ALL curly-braced items in the string-to-sign
TemplateString ts = new TemplateString(msg);
Map valuesMap = new HashMap();
for (String s : ts.variableNames) {
valuesMap.put(s, msgCtxt.getVariable(s));
}
StrSubstitutor sub = new StrSubstitutor(valuesMap);
String resolvedString = sub.replace(ts.template);
return resolvedString;
}
// If the value of a property value begins and ends with curlies,
// and contains no spaces, eg, {apiproxy.name}, then "resolve" the
// value by de-referencing the context variable whose name appears
// between the curlies.
private String resolvePropertyValue(String spec, MessageContext msgCtxt) {
if (spec.startsWith("{") && spec.endsWith("}") && (spec.indexOf(" ") == -1)) {
String varname = spec.substring(1, spec.length() - 1);
String value = msgCtxt.getVariable(varname);
return value;
}
return spec;
}
private void clearVariables(MessageContext msgCtxt) {
msgCtxt.removeVariable("hmac.error");
msgCtxt.removeVariable("hmac.stacktrace");
msgCtxt.removeVariable("hmac.javaizedAlg");
msgCtxt.removeVariable("hmac.alg");
msgCtxt.removeVariable("hmac.string-to-sign");
msgCtxt.removeVariable("hmac.signature.hex");
msgCtxt.removeVariable("hmac.signature.b64");
}
public ExecutionResult execute(MessageContext msgCtxt, ExecutionContext exeCtxt) {
try {
clearVariables(msgCtxt);
String signingKey = getKey(msgCtxt);
String stringToSign = getStringToSign(msgCtxt);
String algorithm = getAlgorithm(msgCtxt);
boolean debug = getDebug(msgCtxt);
msgCtxt.setVariable("hmac.alg", algorithm);
String javaizedAlg = javaizeAlgorithmName(msgCtxt, algorithm);
if (debug) {
msgCtxt.setVariable("hmac.javaizedAlg", javaizedAlg);
}
Mac hmac = Mac.getInstance(javaizedAlg);
SecretKeySpec key = new SecretKeySpec(signingKey.getBytes(), javaizedAlg);
hmac.init(key);
byte[] hmacBytes = hmac.doFinal(stringToSign.getBytes("UTF-8"));
String sigHex = Hex.encodeHexString(hmacBytes);
String sigB64 = Base64.encodeBase64String(hmacBytes);
if (debug) {
msgCtxt.setVariable("hmac.key", signingKey);
}
msgCtxt.setVariable("hmac.string-to-sign", stringToSign);
msgCtxt.setVariable("hmac.signature.hex", sigHex);
msgCtxt.setVariable("hmac.signature.b64", sigB64);
// presence of hmac-base64 property indicates verification wanted
String expectedHmac = getHmac(msgCtxt);
if (expectedHmac != null) {
if (!sigB64.equals(expectedHmac)) {
msgCtxt.setVariable("hmac.error", "HMAC does not verify");
return ExecutionResult.ABORT;
}
}
} catch (Exception e) {
msgCtxt.setVariable("hmac.error", e.getMessage());
msgCtxt.setVariable("hmac.stacktrace", ExceptionUtils.getStackTrace(e));
return ExecutionResult.ABORT;
}
return ExecutionResult.SUCCESS;
}
