SmtpClient.h

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/****
 * Sming Framework Project - Open Source framework for high efficiency native ESP8266 development.
 * Created 2015 by Skurydin Alexey
 * http://github.com/SmingHub/Sming
 * All files of the Sming Core are provided under the LGPL v3 license.
 *
 * SmtpClient.h - Asynchronous SmtpClient that supports the following features:
 *
 * - extended HELO command set
 * - support for PIPELINING
 * - support for STARTTLS (if the directive ENABLE_SSL=1 is set)
 * - support for smtp connection over SSL (if the directive ENABLE_SSL=1 is set)
 * - support for PLAIN and CRAM-MD5 authentication
 * - support for multiple attachments
 * - Support for base64 and quoted-printable transfer encoding
 *
 * Author: 2018 - Slavey Karadzhov <slav@attachix.com>
 *
 ****/

#pragma once

#include "TcpClient.h"
#include <Data/MailMessage.h>
#include "Url.h"
#include <BitManipulations.h>
#include <WString.h>
#include <WVector.h>
#include <Data/Stream/DataSourceStream.h>
#include <WConstants.h>
#include <Data/ObjectQueue.h>

/* Maximum waiting emails in the mail queue */
#define SMTP_QUEUE_SIZE 5

/* Buffer size used to read the error messages */
#define SMTP_ERROR_LENGTH 40

#define SMTP_CODE_SERVICE_READY 220
#define SMTP_CODE_BYE 221
#define SMTP_CODE_AUTH_OK 235
#define SMTP_CODE_REQUEST_OK 250
#define SMTP_CODE_AUTH_CHALLENGE 334
#define SMTP_CODE_START_DATA 354

#define SMTP_OPT_PIPELINE bit(0)
#define SMTP_OPT_STARTTLS bit(1)
#define SMTP_OPT_AUTH_PLAIN bit(2)
#define SMTP_OPT_AUTH_LOGIN bit(3)
#define SMTP_OPT_AUTH_CRAM_MD5 bit(4)

enum SmtpState {
    eSMTP_Banner = 0,
    eSMTP_Hello,
    eSMTP_StartTLS,
    eSMTP_SendAuth,
    eSMTP_SendingAuthLogin,
    eSMTP_RequestingAuthChallenge,
    eSMTP_SendAuthResponse,
    eSMTP_SendingAuth,
    eSMTP_Ready,
    eSMTP_SendMail,
    eSMTP_SendingMail,
    eSMTP_SendRcpt,
    eSMTP_SendingRcpt,
    eSMTP_SendData,
    eSMTP_SendingData,
    eSMTP_SendHeader,
    eSMTP_SendingHeaders,
    eSMTP_StartBody,
    eSMTP_SendingBody,
    eSMTP_Sent,
    eSMTP_Quitting,
    eSMTP_Disconnect
};

class SmtpClient;

using SmtpClientCallback = Delegate<int(SmtpClient& client, int code, char* status)>;

class SmtpClient : protected TcpClient
{
public:
    SmtpClient(bool autoDestroy = false);
    ~SmtpClient();

    bool connect(const Url& url);

    bool send(const String& from, const String& to, const String& subject, const String& body);
    bool send(const String& from, const String& to, const String& subject, String&& body) noexcept;
    bool send(MailMessage* message);

    MailMessage* getCurrentMessage();

    size_t countPending()
    {
        return mailQ.count();
    }

    void quit();

    SmtpState getState()
    {
        return state;
    }

    void onMessageSent(SmtpClientCallback callback)
    {
        messageSentCallback = callback;
    }

    void onServerError(SmtpClientCallback callback)
    {
        errorCallback = callback;
    }

    using TcpClient::getSsl;
    using TcpClient::setSslInitHandler;
    using TcpClient::setTimeOut;

protected:
    err_t onReceive(pbuf* buf) override;
    void onReadyToSendData(TcpConnectionEvent sourceEvent) override;

    void sendMailHeaders(MailMessage* mail);
    bool sendMailBody(MailMessage* mail);

private:
    Url url;
    Vector<String> authMethods;
    ObjectQueue<MailMessage, SMTP_QUEUE_SIZE> mailQ;
    char code[4] = {0};
    int codeValue = 0;
    String authChallenge;
    char message[SMTP_ERROR_LENGTH + 1] = {0};
    bool isLastLine = false;
    uint8_t codeLength = 0;
    int options = 0;
    MailMessage* outgoingMail = nullptr;
    SmtpState state = eSMTP_Banner;

    SmtpClientCallback errorCallback = nullptr;
    SmtpClientCallback messageSentCallback = nullptr;

private:
    int smtpParse(char* data, size_t len);

    MultipartStream::BodyPart multipartProducer();
};