C++ dekodieren E-Mail des Subjektes

Question

ich Mails mit Poco/Net/POP3ClientSession heruntergeladen haben, wollte ich E-Mail-Betreff in für Menschen lesbaren konvertieren, so dass ich versuchte neagoegab's Lösung von hier zu verwenden: https://stackoverflow.com/a/8104496/1350091 leider es doesn‘ t Arbeit:

#include <Poco/Net/POP3ClientSession.h> 
#include <Poco/Net/MailMessage.h> 
#include <iostream> 
#include <string> 
using namespace std; 
using namespace Poco::Net; 


#include <iconv.h> 

const size_t BUF_SIZE=1024; 


class IConv { 
    iconv_t ic_; 
public: 
    IConv(const char* to, const char* from) 
     : ic_(iconv_open(to,from)) { } 
    ~IConv() { iconv_close(ic_); } 

    bool convert(char* input, char* output, size_t& out_size) { 
     size_t inbufsize = strlen(input)+1; 
     return iconv(ic_, &input, &inbufsize, &output, &out_size); 
    } 
}; 


int main() 
{ 
    POP3ClientSession session("poczta.o2.pl"); 
    session.login("my mail", "my password"); 

    POP3ClientSession::MessageInfoVec messages; 
    session.listMessages(messages); 
    cout << "id: " << messages[0].id << " size: " << messages[0].size << endl; 

    MailMessage message; 
    session.retrieveMessage(messages[0].id, message); 
    const string subject = message.getSubject(); 


    cout << "Original subject: " << subject << endl; 

    IConv iconv_("UTF8","ISO-8859-2"); 


    char from[BUF_SIZE];// "=?ISO-8859-2?Q?Re: M=F3j sen o JP II?="; 
    subject.copy(from, sizeof(from)); 
    char to[BUF_SIZE] = "bye"; 
    size_t outsize = BUF_SIZE;//you will need it 

    iconv_.convert(from, to, outsize); 
    cout << "converted: " << to << endl; 
} 

die Ausgabe lautet:

id: 1 size: 2792 
Original subject: =?ISO-8859-2?Q?Re: M=F3j sen o JP II?= 
converted: =?ISO-8859-2?Q?Re: M=F3j sen o JP II?= 

Das interessante daran ist, dass, wenn ich versuche, das Thema mit POCO zu konvertieren es fehlschlägt:

cout << "Encoded with POCO: " << MailMessage::encodeWord("Re: Mój sen o JP II", "ISO-8859-2") << endl; // output: Encoded with POCO: =?ISO-8859-2?q?Re=3A_M=C3=B3j_sen_o_JP_II?= 

Aber das Thema, das ich erhalten möchte, ist: „Re: Mój sen o JP II“ Die einzige erfolgreiche Art, wie ich das Thema konvertieren gefunden ist: https://docs.python.org/2/library/email.header.html#email.header.decode_header

Also meine Frage ist -wie den E-Mail-Betreff in C++ in ein Format wie UTF-8 zu konvertieren?

Answer 1

Ich habe herausgefunden, wie das Problem zu lösen (ich bin mir nicht sicher, dass es 100% richtige Lösung ist), aber es sieht aus wie es ist genug zu verwenden: Poco :: UTF8Encoding :: konvertieren von CharacterCode zu konvertieren utf8:

#include <Poco/Net/POP3ClientSession.h> 
#include <Poco/Net/MessageHeader.h> 
#include <Poco/Net/MailMessage.h> 
#include <Poco/UTF8Encoding.h> 
#include <iostream> 
#include <string> 

using namespace std; 
using namespace Poco::Net; 

class EncoderLatin2 
{ 
public: 
    EncoderLatin2(const string& encodedSubject) 
    { 
     /// encoded-word = "=?" charset "?" encoding "?" encoded-text "?=" 
     int charsetBeginPosition = strlen("=?"); 
     int charsetEndPosition = encodedSubject.find("?", charsetBeginPosition); 
     charset = encodedSubject.substr(charsetBeginPosition, charsetEndPosition-charsetBeginPosition); 

     int encodingPosition = charsetEndPosition + strlen("?"); 
     encoding = encodedSubject[encodingPosition]; 

     if ("ISO-8859-2" != charset) 
      throw std::invalid_argument("Invalid encoding!"); 

     const int lenghtOfEncodedText = encodedSubject.length() - encodingPosition-strlen("?=")-2; 
     extractedEncodedSubjectToConvert = encodedSubject.substr(encodingPosition+2, lenghtOfEncodedText); 
    } 

    string convert() 
    { 
     size_t positionOfAssignment = -1; 

     while (true) 
     { 
      positionOfAssignment = extractedEncodedSubjectToConvert.find('=', positionOfAssignment+1); 
      if (string::npos != positionOfAssignment) 
      { 
       const string& charHexCode = extractedEncodedSubjectToConvert.substr(positionOfAssignment + 1, 2); 
       replaceAllSubstringsWithUnicode(extractedEncodedSubjectToConvert, charHexCode); 
      } 
      else 
       break; 
     } 
     return extractedEncodedSubjectToConvert; 
    } 

    void replaceAllSubstringsWithUnicode(string& s, const string& charHexCode) 
    { 
     const int charCode = stoi(charHexCode, nullptr, 16); 

     char buffer[10] = {}; 
     encodingConverter.convert(charCode, (unsigned char*)buffer, sizeof(buffer)); 
     replaceAll(s, '=' + charHexCode, buffer); 
    } 

    void replaceAll(string& s, const string& replaceFrom, const string& replaceTo) 
    { 
     size_t needlePosition = -1; 
     while (true) 
     { 
      needlePosition = s.find(replaceFrom, needlePosition + 1); 
      if (string::npos == needlePosition) 
       break; 

      s.replace(needlePosition, replaceFrom.length(), replaceTo); 
     } 
    } 


private: 
    string charset; 
    char encoding; 
    Poco::UTF8Encoding encodingConverter; 

    string extractedEncodedSubjectToConvert; 
}; 

int main() 
{ 
    POP3ClientSession session("poczta.o2.pl"); 
    session.login("my mail", "my password"); 


    POP3ClientSession::MessageInfoVec messages; 
    session.listMessages(messages); 

    MessageHeader header; 
    MailMessage message; 

    auto currentMessage = messages[0]; 

    session.retrieveHeader(currentMessage.id, header); 
    session.retrieveMessage(currentMessage.id, message); 

    const string subject = message.getSubject(); 

    EncoderLatin2 encoder(subject); 
    cout << "Original subject: " << subject << endl; 
    cout << "Encoded: " << encoder.convert() << endl; 
} 

Answer 2

Der relevante RFC zu Ihrer Situation ist RFC 2047. Dieser RFC gibt an, wie Nicht-ASCII-Daten in E-Mail-Nachrichten codiert werden sollen. Der Grundgedanke ist, dass neben druckbaren ASCII-Zeichen alle Bytes als '=' - Zeichen gefolgt von zwei Hexadezimalziffern ausgeblendet werden. Da "ó" in ISO-8859-2 durch das Byte 0xF3 dargestellt wird und 0xF3 kein druckbares ASCII-Zeichen ist, wird es als "= F3" codiert. Sie müssen alle codierten Zeichen in Ihrer Nachricht dekodieren.

Answer 3

Ich fand eine andere Lösung, besser als vorher. Einige E-Mails Themen unterschiedliche Kodierungen hat, bemerkte ich:

• Latin2, codiert wie: = ISO-8859-2 Q ... =
• UTF-8 Base64 wie:??? = ? utf-8 B Wm9iYWN6Y2llIGNvIGRsYSBXYXMgcHJ6eWdvdG93YWxpxZtteSAvIHN0eWN6ZcWEIHcgTGFzZXJwYXJrdQ == =
• UTF-8 quoted-printable wie:????? = utf-8 Q ... =
• Keine Codierung (wenn auch nur ASCII-Zeichen) wie?:. ..

Also mit POCO (Base64Decoder, Latin2Encoding, UTF8Encoding, QuotedPrintableDecoder) habe ich es geschafft, alle Fälle zu konvertieren:

#include <iostream> 
#include <string> 
#include <sstream> 

#include <Poco/Net/POP3ClientSession.h> 
#include <Poco/Net/MessageHeader.h> 
#include <Poco/Net/MailMessage.h> 
#include <Poco/Base64Decoder.h> 
#include <Poco/Latin2Encoding.h> 
#include <Poco/UTF8Encoding.h> 
#include <Poco/Net/QuotedPrintableDecoder.h> 

using namespace std; 

class Encoder 
{ 
public: 
    Encoder(const string& encodedText) 
    { 
     isStringEncoded = isEncoded(encodedText); 
     if (!isStringEncoded) 
     { 
      extractedEncodedSubjectToConvert = encodedText; 
      return; 
     } 

     splitEncodedText(encodedText); 
    } 

    string convert() 
    { 
     if (isStringEncoded) 
     { 
      if (Poco::Latin2Encoding().isA(charset)) 
       return decodeFromLatin2(); 
      if (Poco::UTF8Encoding().isA(charset)) 
       return decodeFromUtf8(); 
     } 

     return extractedEncodedSubjectToConvert; 
    } 

private: 
    void splitEncodedText(const string& encodedText) 
    { 
     /// encoded-word = "=?" charset "?" encoding "?" encoded-text "?=" 
     const int charsetBeginPosition = strlen(sequenceBeginEncodedText); 
     const int charsetEndPosition = encodedText.find("?", charsetBeginPosition); 
     charset = encodedText.substr(charsetBeginPosition, charsetEndPosition-charsetBeginPosition); 

     const int encodingPosition = charsetEndPosition + strlen("?"); 
     encoding = encodedText[encodingPosition]; 

     const int lenghtOfEncodedText = encodedText.length() - encodingPosition-strlen(sequenceBeginEncodedText)-strlen(sequenceEndEncodedText); 
     extractedEncodedSubjectToConvert = encodedText.substr(encodingPosition+2, lenghtOfEncodedText); 
    } 

    bool isEncoded(const string& encodedSubject) 
    { 
     if (encodedSubject.size() < 4) 
      return false; 

     if (0 != encodedSubject.find(sequenceBeginEncodedText)) 
      return false; 

     const unsigned positionOfLastTwoCharacters = encodedSubject.size() - strlen(sequenceEndEncodedText); 
     return positionOfLastTwoCharacters == encodedSubject.rfind(sequenceEndEncodedText); 
    } 

    string decodeFromLatin2() 
    { 
     size_t positionOfAssignment = -1; 
     while (true) 
     { 
      positionOfAssignment = extractedEncodedSubjectToConvert.find('=', positionOfAssignment+1); 
      if (string::npos != positionOfAssignment) 
      { 
       const string& charHexCode = extractedEncodedSubjectToConvert.substr(positionOfAssignment + 1, 2); 
       replaceAllSubstringsWithUnicode(extractedEncodedSubjectToConvert, charHexCode); 
      } 
      else 
       break; 
     } 
     return extractedEncodedSubjectToConvert; 
    } 

    void replaceAllSubstringsWithUnicode(string& s, const string& charHexCode) 
    { 
     static Poco::UTF8Encoding encodingConverter; 
     const int charCode = stoi(charHexCode, nullptr, 16); 

     char buffer[10] = {}; 
     encodingConverter.convert(charCode, (unsigned char*)buffer, sizeof(buffer)); 
     replaceAll(s, '=' + charHexCode, buffer); 
    } 

    void replaceAll(string& s, const string& replaceFrom, const string& replaceTo) 
    { 
     size_t needlePosition = -1; 
     while (true) 
     { 
      needlePosition = s.find(replaceFrom, needlePosition + 1); 
      if (string::npos == needlePosition) 
       break; 

      s.replace(needlePosition, replaceFrom.length(), replaceTo); 
     } 
    } 

    string decodeFromUtf8() 
    { 
     if('B' == toupper(encoding)) 
     { 
      return decodeFromBase64(); 
     } 
     else // if Q: 
     { 
      return decodeFromQuatedPrintable(); 
     } 
    } 

    string decodeFromBase64() 
    { 
     istringstream is(extractedEncodedSubjectToConvert); 
     Poco::Base64Decoder e64(is); 

     extractedEncodedSubjectToConvert.clear(); 
     string buffer; 
     while(getline(e64, buffer)) 
      extractedEncodedSubjectToConvert += buffer; 
     return extractedEncodedSubjectToConvert; 
    } 

    string decodeFromQuatedPrintable() 
    { 
     replaceAll(extractedEncodedSubjectToConvert, "_", " "); 


     istringstream is(extractedEncodedSubjectToConvert); 
     Poco::Net::QuotedPrintableDecoder qp(is); 

     extractedEncodedSubjectToConvert.clear(); 
     string buffer; 
     while(getline(qp, buffer)) 
      extractedEncodedSubjectToConvert += buffer; 
     return extractedEncodedSubjectToConvert; 
    } 


private: 
    string charset; 
    char encoding; 

    string extractedEncodedSubjectToConvert; 
    bool isStringEncoded; 

    static constexpr const char* sequenceBeginEncodedText = "=?"; 
    static constexpr const char* sequenceEndEncodedText = "?="; 
}; 

int main() 
{ 
    Poco::Net::POP3ClientSession session("poczta.o2.pl"); 
    session.login("my mail", "my password"); 

    Poco::Net::POP3ClientSession::MessageInfoVec messages; 
    session.listMessages(messages); 

    Poco::Net::MessageHeader header; 
    Poco::Net::MailMessage message; 

    auto currentMessage = messages[0]; 

    session.retrieveHeader(currentMessage.id, header); 
    session.retrieveMessage(currentMessage.id, message);  

    const string subject = message.getSubject(); 

    Encoder encoder(subject); 
    cout << "Original subject: " << subject << endl; 
    cout << "Encoded: " << encoder.convert() << endl; 
}