/src/logging-log4cxx/src/main/cpp/smtpappender.cpp

Source
/*
 * 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 <log4cxx/net/smtpappender.h>
#include <log4cxx/level.h>
#include <log4cxx/helpers/loglog.h>
#include <log4cxx/helpers/optionconverter.h>
#include <log4cxx/spi/loggingevent.h>
#include <log4cxx/private/string_c11.h>
#include <log4cxx/helpers/stringhelper.h>
#include <log4cxx/helpers/stringtokenizer.h>
#include <log4cxx/helpers/transcoder.h>
#include <log4cxx/helpers/loader.h>
#if !defined(LOG4CXX)
  #define LOG4CXX 1
#endif
#include <log4cxx/private/log4cxx_private.h>
#include <log4cxx/private/appenderskeleton_priv.h>


#include <apr_strings.h>
#include <vector>

using namespace LOG4CXX_NS;
using namespace LOG4CXX_NS::helpers;
using namespace LOG4CXX_NS::net;
using namespace LOG4CXX_NS::spi;

#if LOG4CXX_HAVE_LIBESMTP
  #include <auth-client.h>
  #include <libesmtp.h>
#endif

namespace
{
// RFC 5322 §2.1 defines header fields as CRLF-terminated lines, so an embedded
// CR or LF in a configured Subject/From/To/Cc/Bcc value would split it across
// header boundaries on the wire — a caller who controls a configured field
// (e.g. through ${...} property substitution from an environment variable)
// could inject arbitrary additional headers such as Bcc. The library already
// owns SMTP wire-format sanitization (see SMTPSession::toAscii, which silently
// rewrites non-ASCII to '?'); strip CR/LF in the public setters so the same
// boundary is enforced regardless of how the value reaches the appender.
LogString stripSmtpControl(const LogString& value, const logchar* field)
{
  if (value.find_first_of(LOG4CXX_STR("\r\n")) == LogString::npos)
  {
    return value;
  }
  LogString warning(LOG4CXX_STR("SMTPAppender "));
  warning.append(field);
  warning.append(LOG4CXX_STR(" contains CR or LF; stripping to prevent SMTP header injection."));
  LogLog::warn(warning);
  LogString out;
  out.reserve(value.size());
  for (auto ch : value)
  {
    if (ch != 0x0D && ch != 0x0A)
    {
      out.append(1, ch);
    }
  }
  return out;
}
} // namespace

namespace LOG4CXX_NS
{
namespace net
{
//
//   The following two classes implement an C++ SMTP wrapper over libesmtp.
//   The same signatures could be implemented over different SMTP implementations
//   or libesmtp could be combined with libgmime to enable support for non-ASCII
//   content.

#if LOG4CXX_HAVE_LIBESMTP
/**
 *   SMTP Session.
 */
class SMTPSession
{
  public:
    /**
    *   Create new instance.
    */
    SMTPSession(const LogString& smtpHost,
      int smtpPort,
      const LogString& smtpUsername,
      const LogString& smtpPassword,
      Pool& p) : session(0), authctx(0),
      user(toAscii(smtpUsername, p)),
      pwd(toAscii(smtpPassword, p))
    {
      auth_client_init();
      session = smtp_create_session();

      if (session == 0)
      {
        throw Exception("Could not initialize session.");
      }

      std::string host(toAscii(smtpHost, p));
      host.append(1, ':');
      host.append(p.itoa(smtpPort));
      smtp_set_server(session, host.c_str());

      authctx = auth_create_context();
      auth_set_mechanism_flags(authctx, AUTH_PLUGIN_PLAIN, 0);
      auth_set_interact_cb(authctx, authinteract, (void*) this);

      if (*user || *pwd)
      {
        smtp_auth_set_context(session, authctx);
      }
    }

    ~SMTPSession()
    {
      smtp_destroy_session(session);
      auth_destroy_context(authctx);
    }

    void send(Pool& p)
    {
      int status = smtp_start_session(session);

      if (!status)
      {
        size_t bufSize = 128;
        char* buf = p.pstralloc(bufSize);
        smtp_strerror(smtp_errno(), buf, bufSize);
        throw Exception(buf);
      }
    }

    operator smtp_session_t()
    {
      return session;
    }

    static char* toAscii(const LogString& str, Pool& p)
    {
      char* buf = p.pstralloc(str.length() + 1);
      char* current = buf;

      for (unsigned int c : str)
      {
        if (c > 0x7F)
        {
          c = '?';
        }

        *current++ = c;
      }

      *current = 0;
      return buf;
    }

  private:
    SMTPSession(SMTPSession&);
    SMTPSession& operator=(SMTPSession&);
    smtp_session_t session;
    auth_context_t authctx;
    char* user;
    char* pwd;

    /**
     *   This method is called if the SMTP server requests authentication.
     */
    static int authinteract(auth_client_request_t request, char** result, int fields,
      void* arg)
    {
      SMTPSession* pThis = (SMTPSession*) arg;

      for (int i = 0; i < fields; i++)
      {
        int flag = request[i].flags & 0x07;

        if (flag == AUTH_USER)
        {
          result[i] = pThis->user;
        }
        else if (flag == AUTH_PASS)
        {
          result[i] = pThis->pwd;
        }
      }

      return 1;
    }


};

/**
 *  A message in an SMTP session.
 */
class SMTPMessage
{
  public:
    SMTPMessage(SMTPSession& session,
      const LogString& from,
      const LogString& to,
      const LogString& cc,
      const LogString& bcc,
      const LogString& subject,
      const LogString msg, Pool& p)
    {
      message = smtp_add_message(session);
      current_len = msg.length();
      body = current = toMessage(msg, p);
      messagecbState = 0;
      smtp_set_reverse_path(message, toAscii(from, p));
      addRecipients(to, "To", p);
      addRecipients(cc, "Cc", p);
      addRecipients(bcc, "Bcc", p);

      if (!subject.empty())
      {
        smtp_set_header(message, "Subject", toAscii(subject, p));
      }

      smtp_set_messagecb(message, messagecb, this);
    }
    ~SMTPMessage()
    {
    }

  private:
    SMTPMessage(const SMTPMessage&);
    SMTPMessage& operator=(const SMTPMessage&);
    smtp_message_t message;
    const char* body;
    const char* current;
    size_t current_len;
    int messagecbState;
    void addRecipients(const LogString& addresses, const char* field, Pool& p)
    {
      if (!addresses.empty())
      {
        char* str = p.pstrdup(toAscii(addresses, p));;
        smtp_set_header(message, field, NULL, str);
        char* last;

        for (char* next = apr_strtok(str, ",", &last);
          next;
          next = apr_strtok(NULL, ",", &last))
        {
          smtp_add_recipient(message, next);
        }
      }
    }
    static const char* toAscii(const LogString& str, Pool& p)
    {
      return SMTPSession::toAscii(str, p);
    }

    /**
     *   Message bodies can only contain US-ASCII characters and
     *   CR and LFs can only occur together.
     */
    static const char* toMessage(const LogString& str, Pool& p)
    {
      //
      //    count the number of carriage returns and line feeds
      //
      int feedCount = 0;

      for (size_t pos = str.find_first_of(LOG4CXX_STR("\n\r"));
        pos != LogString::npos;
        pos = str.find_first_of(LOG4CXX_STR("\n\r"), ++pos))
      {
        feedCount++;
      }

      //
      //   allocate sufficient space for the modified message
      char* retval = p.pstralloc(str.length() + feedCount + 1);
      char* current = retval;
      char* startOfLine = current;
      unsigned int ignoreChar = 0;

      //
      //    iterator through message
      //
      for (unsigned int c : str)
      {
        //
        //   replace non-ASCII characters with '?'
        //
        if (c > 0x7F)
        {
          *current++ = 0x3F; // '?'
        }
        else if (c == 0x0A || c == 0x0D)
        {
          //
          //   replace any stray CR or LF with CRLF
          //      reset start of line
          if (c == ignoreChar && current == startOfLine)
            ignoreChar = 0;
          else
          {
            *current++ = 0x0D;
            *current++ = 0x0A;
            startOfLine = current;
            ignoreChar = (c == 0x0A ? 0x0D : 0x0A);
          }
        }
        else
        {
          //
          //    truncate any lines to 1000 characters (including CRLF)
          //       as required by RFC.
          if (current < startOfLine + 998)
          {
            *current++ = (char) c;
          }
        }
      }

      *current = 0;
      return retval;
    }

    /**
     *  Callback for message.
     */
    static const char* messagecb(void** ctx, int* len, void* arg)
    {
      *ctx = 0;
      const char* retval = 0;
      SMTPMessage* pThis = (SMTPMessage*) arg;

      //   rewind message
      if (len == NULL)
      {
        pThis->current = pThis->body;
      }
      else
      {
        // we are asked for headers, but we don't have any
        if ((pThis->messagecbState)++ == 0)
        {
          return NULL;
        }

        if (pThis->current)
        {
          *len = strnlen_s(pThis->current, pThis->current_len);
        }

        retval = pThis->current;
        pThis->current = 0;
      }

      return retval;
    }

};
#endif

class LOG4CXX_EXPORT DefaultEvaluator
#if LOG4CXX_ABI_VERSION <= 15
  : public virtual spi::TriggeringEventEvaluator
  , public virtual helpers::Object
#else
  : public spi::TriggeringEventEvaluator
#endif
{
  public:
    DECLARE_LOG4CXX_OBJECT(DefaultEvaluator)
    BEGIN_LOG4CXX_CAST_MAP()
    LOG4CXX_CAST_ENTRY(DefaultEvaluator)
    LOG4CXX_CAST_ENTRY(spi::TriggeringEventEvaluator)
    END_LOG4CXX_CAST_MAP()

    DefaultEvaluator();

    /**
    Is this <code>event</code> the e-mail triggering event?
    <p>This method returns <code>true</code>, if the event level
    has ERROR level or higher. Otherwise it returns
    <code>false</code>.
    */
    bool isTriggeringEvent(const spi::LoggingEventPtr& event) override;
  private:
    DefaultEvaluator(const DefaultEvaluator&);
    DefaultEvaluator& operator=(const DefaultEvaluator&);
}; // class DefaultEvaluator

}
}

IMPLEMENT_LOG4CXX_OBJECT(DefaultEvaluator)
IMPLEMENT_LOG4CXX_OBJECT(SMTPAppender)

struct SMTPAppender::SMTPPriv : public AppenderSkeletonPrivate
{
  SMTPPriv() :
    AppenderSkeletonPrivate(),
    smtpPort(25),
    bufferSize(512),
    locationInfo(false),
    cb(bufferSize),
    evaluator(new DefaultEvaluator()) {}

  SMTPPriv(spi::TriggeringEventEvaluatorPtr evaluator) :
    AppenderSkeletonPrivate(),
    smtpPort(25),
    bufferSize(512),
    locationInfo(false),
    cb(bufferSize),
    evaluator(evaluator) {}

  LogString to;
  LogString cc;
  LogString bcc;
  LogString from;
  LogString subject;
  LogString smtpHost;
  LogString smtpUsername;
  LogString smtpPassword;
  int smtpPort;
  int bufferSize; // 512
  bool locationInfo;
  helpers::CyclicBuffer cb;
  spi::TriggeringEventEvaluatorPtr evaluator;
};

#define _priv static_cast<SMTPPriv*>(m_priv.get())

DefaultEvaluator::DefaultEvaluator()
{
}

bool DefaultEvaluator::isTriggeringEvent(const spi::LoggingEventPtr& event)
{
  return event->getLevel()->isGreaterOrEqual(Level::getError());
}

SMTPAppender::SMTPAppender()
  : AppenderSkeleton (std::make_unique<SMTPPriv>())
{
}

/**
Use <code>evaluator</code> passed as parameter as the
TriggeringEventEvaluator for this SMTPAppender.  */
SMTPAppender::SMTPAppender(spi::TriggeringEventEvaluatorPtr evaluator)
  : AppenderSkeleton (std::make_unique<SMTPPriv>(evaluator))
{
}

SMTPAppender::~SMTPAppender()
{
  _priv->setClosed();
}

bool SMTPAppender::requiresLayout() const
{
  return true;
}

LogString SMTPAppender::getFrom() const
{
  return _priv->from;
}

void SMTPAppender::setFrom(const LogString& newVal)
{
  _priv->from = stripSmtpControl(newVal, LOG4CXX_STR("From"));
}


LogString SMTPAppender::getSubject() const
{
  return _priv->subject;
}

void SMTPAppender::setSubject(const LogString& newVal)
{
  _priv->subject = stripSmtpControl(newVal, LOG4CXX_STR("Subject"));
}

LogString SMTPAppender::getSMTPHost() const
{
  return _priv->smtpHost;
}

void SMTPAppender::setSMTPHost(const LogString& newVal)
{
  _priv->smtpHost = newVal;
}

int SMTPAppender::getSMTPPort() const
{
  return _priv->smtpPort;
}

void SMTPAppender::setSMTPPort(int newVal)
{
  _priv->smtpPort = newVal;
}

bool SMTPAppender::getLocationInfo() const
{
  return _priv->locationInfo;
}

void SMTPAppender::setLocationInfo(bool newVal)
{
  _priv->locationInfo = newVal;
}

LogString SMTPAppender::getSMTPUsername() const
{
  return _priv->smtpUsername;
}

void SMTPAppender::setSMTPUsername(const LogString& newVal)
{
  _priv->smtpUsername = newVal;
}

LogString SMTPAppender::getSMTPPassword() const
{
  return _priv->smtpPassword;
}

void SMTPAppender::setSMTPPassword(const LogString& newVal)
{
  _priv->smtpPassword = newVal;
}





void SMTPAppender::setOption(const LogString& option,
  const LogString& value)
{
  if (StringHelper::equalsIgnoreCase(option, LOG4CXX_STR("BUFFERSIZE"), LOG4CXX_STR("buffersize")))
  {
    setBufferSize(OptionConverter::toInt(value, 512));
  }
  else if (StringHelper::equalsIgnoreCase(option, LOG4CXX_STR("EVALUATORCLASS"), LOG4CXX_STR("evaluatorclass")))
  {
    setEvaluatorClass(value);
  }
  else if (StringHelper::equalsIgnoreCase(option, LOG4CXX_STR("FROM"), LOG4CXX_STR("from")))
  {
    setFrom(value);
  }
  else if (StringHelper::equalsIgnoreCase(option, LOG4CXX_STR("SMTPHOST"), LOG4CXX_STR("smtphost")))
  {
    setSMTPHost(value);
  }
  else if (StringHelper::equalsIgnoreCase(option, LOG4CXX_STR("SMTPUSERNAME"), LOG4CXX_STR("smtpusername")))
  {
    setSMTPUsername(value);
  }
  else if (StringHelper::equalsIgnoreCase(option, LOG4CXX_STR("SMTPPASSWORD"), LOG4CXX_STR("smtppassword")))
  {
    setSMTPPassword(value);
  }
  else if (StringHelper::equalsIgnoreCase(option, LOG4CXX_STR("SUBJECT"), LOG4CXX_STR("subject")))
  {
    setSubject(value);
  }
  else if (StringHelper::equalsIgnoreCase(option, LOG4CXX_STR("TO"), LOG4CXX_STR("to")))
  {
    setTo(value);
  }
  else if (StringHelper::equalsIgnoreCase(option, LOG4CXX_STR("CC"), LOG4CXX_STR("cc")))
  {
    setCc(value);
  }
  else if (StringHelper::equalsIgnoreCase(option, LOG4CXX_STR("BCC"), LOG4CXX_STR("bcc")))
  {
    setBcc(value);
  }
  else if (StringHelper::equalsIgnoreCase(option, LOG4CXX_STR("SMTPPORT"), LOG4CXX_STR("smtpport")))
  {
    setSMTPPort(OptionConverter::toInt(value, 25));
  }
  else
  {
    AppenderSkeleton::setOption(option, value);
  }
}


bool SMTPAppender::asciiCheck(const LogString& value, const LogString& field)
{
  for (unsigned int item : value)
  {
    if (0x7F < item)
    {
      LogLog::warn(field + LOG4CXX_STR(" contains non-ASCII character"));
      return false;
    }
  }

  return true;
}

/**
Activate the specified options, such as the smtp host, the
recipient, from, etc. */
void SMTPAppender::activateOptions( LOG4CXX_ACTIVATE_OPTIONS_FORMAL_PARAMETERS )
{
  if (_priv->layout == 0)
  {
    _priv->errorHandler->error(LOG4CXX_STR("No layout set for appender named [") + _priv->name + LOG4CXX_STR("]."));
  }

  if (_priv->evaluator == 0)
  {
    _priv->errorHandler->error(LOG4CXX_STR("No TriggeringEventEvaluator is set for appender [") +
      _priv->name + LOG4CXX_STR("]."));
  }

  if (_priv->smtpHost.empty())
  {
    _priv->errorHandler->error(LOG4CXX_STR("No smtpHost is set for appender [") +
      _priv->name + LOG4CXX_STR("]."));
  }

  if (_priv->to.empty() && _priv->cc.empty() && _priv->bcc.empty())
  {
    _priv->errorHandler->error(LOG4CXX_STR("No recipient address is set for appender [") +
      _priv->name + LOG4CXX_STR("]."));
  }

  asciiCheck(_priv->to, LOG4CXX_STR("to"));
  asciiCheck(_priv->cc, LOG4CXX_STR("cc"));
  asciiCheck(_priv->bcc, LOG4CXX_STR("bcc"));
  asciiCheck(_priv->from, LOG4CXX_STR("from"));

#if !LOG4CXX_HAVE_LIBESMTP
  _priv->errorHandler->error(LOG4CXX_STR("log4cxx built without SMTP support."));
#endif
}

/**
Perform SMTPAppender specific appending actions, mainly adding
the event to a cyclic buffer and checking if the event triggers
an e-mail to be sent. */
void SMTPAppender::append( LOG4CXX_APPEND_FORMAL_PARAMETERS )
{
  if (!checkEntryConditions())
  {
    return;
  }

  // Get a copy of this thread's diagnostic context
  event->LoadDC();

  _priv->cb.add(event);

  if (_priv->evaluator->isTriggeringEvent(event))
  {
    Pool p;
    sendBuffer(p);
  }
}

/**
This method determines if there is a sense in attempting to append.
<p>It checks whether there is a set output target and also if
there is a set layout. If these checks fail, then the boolean
value <code>false</code> is returned. */
bool SMTPAppender::checkEntryConditions()
{
#if LOG4CXX_HAVE_LIBESMTP

  if ((_priv->to.empty() && _priv->cc.empty() && _priv->bcc.empty()) || _priv->from.empty() || _priv->smtpHost.empty())
  {
    _priv->errorHandler->error(LOG4CXX_STR("Message not configured."));
    return false;
  }

  if (_priv->evaluator == 0)
  {
    _priv->errorHandler->error(LOG4CXX_STR("No TriggeringEventEvaluator is set for appender [") +
      _priv->name + LOG4CXX_STR("]."));
    return false;
  }


  if (_priv->layout == 0)
  {
    _priv->errorHandler->error(LOG4CXX_STR("No layout set for appender named [") + _priv->name + LOG4CXX_STR("]."));
    return false;
  }

  return true;
#else
  return false;
#endif
}



void SMTPAppender::close()
{
  _priv->setClosed();
}

LogString SMTPAppender::getTo() const
{
  return _priv->to;
}

void SMTPAppender::setTo(const LogString& addressStr)
{
  _priv->to = stripSmtpControl(addressStr, LOG4CXX_STR("To"));
}

LogString SMTPAppender::getCc() const
{
  return _priv->cc;
}

void SMTPAppender::setCc(const LogString& addressStr)
{
  _priv->cc = stripSmtpControl(addressStr, LOG4CXX_STR("Cc"));
}

LogString SMTPAppender::getBcc() const
{
  return _priv->bcc;
}

void SMTPAppender::setBcc(const LogString& addressStr)
{
  _priv->bcc = stripSmtpControl(addressStr, LOG4CXX_STR("Bcc"));
}

/**
Send the contents of the cyclic buffer as an e-mail message.
*/
void SMTPAppender::sendBuffer(Pool& p)
{
#if LOG4CXX_HAVE_LIBESMTP

  // Note: this code already owns the monitor for this
  // appender. This frees us from needing to synchronize on 'cb'.
  try
  {
    LogString sbuf;
    _priv->layout->appendHeader(sbuf);

    int len = _priv->cb.length();

    for (int i = 0; i < len; i++)
    {
      LoggingEventPtr event = _priv->cb.get();
      _priv->layout->format(sbuf, event);
    }

    _priv->layout->appendFooter(sbuf);

    SMTPSession session(_priv->smtpHost, _priv->smtpPort, _priv->smtpUsername, _priv->smtpPassword, p);

    SMTPMessage message(session, _priv->from, _priv->to, _priv->cc,
      _priv->bcc, _priv->subject, sbuf, p);

    session.send(p);

  }
  catch (std::exception& e)
  {
    _priv->errorHandler->error(LOG4CXX_STR("Error occured while sending e-mail to [") + _priv->smtpHost + LOG4CXX_STR("]."), e, 0);
  }

#endif
}

/**
Returns value of the <b>EvaluatorClass</b> option.
*/
LogString SMTPAppender::getEvaluatorClass()
{
  return _priv->evaluator == 0 ? LogString() : _priv->evaluator->getClass().getName();
}

LOG4CXX_NS::spi::TriggeringEventEvaluatorPtr SMTPAppender::getEvaluator() const
{
  return _priv->evaluator;
}

void SMTPAppender::setEvaluator(LOG4CXX_NS::spi::TriggeringEventEvaluatorPtr& trigger)
{
  _priv->evaluator = trigger;
}

/**
The <b>BufferSize</b> option takes a positive integer
representing the maximum number of logging events to collect in a
cyclic buffer. When the <code>BufferSize</code> is reached,
oldest events are deleted as new events are added to the
buffer. By default the size of the cyclic buffer is 512 events.
*/
void SMTPAppender::setBufferSize(int sz)
{
  if (sz < 1)
  {
    sz = 1;
  }

  _priv->bufferSize = sz;
  _priv->cb.resize(sz);
}

/**
The <b>EvaluatorClass</b> option takes a string value
representing the name of the class implementing the {@link
TriggeringEventEvaluator} interface. A corresponding object will
be instantiated and assigned as the triggering event evaluator
for the SMTPAppender.
*/
void SMTPAppender::setEvaluatorClass(const LogString& value)
{
  ObjectPtr obj = ObjectPtr(Loader::loadClass(value).newInstance());
  _priv->evaluator = LOG4CXX_NS::cast<TriggeringEventEvaluator>(obj);
}

int SMTPAppender::getBufferSize() const
{
  return _priv->bufferSize;
}

Coverage Report

Created: 2026-05-30 06:57