example/plugins/c-api/verify_cert/verify_cert.cc

/** @file

  Verify certificate test plugin.

  Example showing how to use TS_SSL_VERIFY_CLIENT_HOOK

  @section license License

  Licensed to the Apache Software Foundation (ASF) under one
  or more contributor license agreements.  See the NOTICE file
  distributed with this work for additional information
  regarding copyright ownership.  The ASF licenses this file
  to you under the Apache License, Version 2.0 (the
  "License"); you may not use this file except in compliance
  with the License.  You may obtain a copy of the License at

      http://www.apache.org/licenses/LICENSE-2.0

  Unless required by applicable law or agreed to in writing, software
  distributed under the License is distributed on an "AS IS" BASIS,
  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  See the License for the specific language governing permissions and
  limitations under the License.
 */

#include <cstdio>
#include <memory.h>
#include <cinttypes>
#include <ts/ts.h>
#include <openssl/ssl.h>

#define PLUGIN_NAME "verify_cert"
#define PCP         "[" PLUGIN_NAME "] "

namespace
{
DbgCtl dbg_ctl{PLUGIN_NAME};

static void
debug_certificate(const char *msg, const X509_NAME *name)
{
  BIO *bio;

  if (name == nullptr) {
    return;
  }

  bio = BIO_new(BIO_s_mem());
  if (bio == nullptr) {
    return;
  }

  if (X509_NAME_print_ex(bio, name, 0 /* indent */, XN_FLAG_ONELINE) > 0) {
    long  len;
    char *ptr;
    len = BIO_get_mem_data(bio, &ptr);
    Dbg(dbg_ctl, "%s %.*s", msg, static_cast<int>(len), ptr);
  }

  BIO_free(bio);
}

int
CB_clientcert(TSCont /* contp */, TSEvent /* event */, void *edata)
{
  TSVConn         ssl_vc = reinterpret_cast<TSVConn>(edata);
  TSSslConnection sslobj = TSVConnSslConnectionGet(ssl_vc);
  SSL            *ssl    = reinterpret_cast<SSL *>(sslobj);
#ifdef OPENSSL_IS_AT_LEAST_OPENSSL3
  X509 *cert = SSL_get1_peer_certificate(ssl);
#else
  X509 *cert = SSL_get_peer_certificate(ssl);
#endif
  Dbg(dbg_ctl, "plugin verify_cert verifying client certificate");
  if (cert) {
    debug_certificate("client certificate subject CN is %s", X509_get_subject_name(cert));
    debug_certificate("client certificate issuer CN is %s", X509_get_issuer_name(cert));
    X509_free(cert);
  }
  // All done, reactivate things
  TSVConnReenable(ssl_vc);
  return TS_SUCCESS;
}

} // namespace

// Called by ATS as our initialization point
void
TSPluginInit(int /* argc ATS_UNUSED */, const char ** /* argv ATS_UNUSED */)
{
  bool                     success = false;
  TSPluginRegistrationInfo info;
  TSCont                   cb_cert = nullptr; // Certificate callback continuation

  info.plugin_name   = PLUGIN_NAME;
  info.vendor_name   = "Apache Software Foundation";
  info.support_email = "dev@trafficserver.apache.org";

  if (TS_SUCCESS != TSPluginRegister(&info)) {
    TSError(PCP "registration failed");
  } else if (nullptr == (cb_cert = TSContCreate(&CB_clientcert, TSMutexCreate()))) {
    TSError(PCP "Failed to create cert callback");
  } else {
    TSHttpHookAdd(TS_SSL_VERIFY_CLIENT_HOOK, cb_cert);
    success = true;
  }

  if (!success) {
    TSError(PCP "not initialized");
  }
  Dbg(dbg_ctl, "Plugin %s", success ? "online" : "offline");

  return;
}