C # obtain the email code (body and attachment) through POP3)

Usage:
Get 1st emails CopyCode The Code is as follows: zgke. net. POP3 _ popt = new zgke. net. POP3 ("192.168.0.1", 110 );
Datatable _ mail = _ popt. getmail ("zk", "zk", 1 );

The returned datatable data content is
Type is type text is text, if the attachment is byte [] Name, if the attachment is stored as the file name

Below are all classesCopy codeThe Code is as follows: using system;
Using system. net. Sockets;
Using system. net;
Using system. Security. cryptography;
Using system. IO;
Using system. Data;

Namespace zgke. net
{

/// <Summary>
/// Obtain mail class
// Zgke@sina.com
/// QQ: 116149
/// </Summary>
Public class POP3
{
Private string m_address = "127.0.0.1 ";

Private int m_port = 110;

Public POP3 (string p_address, int p_port)
{
M_address = p_address;
M_port = p_port;
}

/// <Summary>
/// Obtain the mail list
/// </Summary>
/// <Param name = "p_name"> User Name </param>
/// <Param name = "p_password"> password </param>
/// <Returns> Mail Information </returns>
Public datatable getmailtable (string p_name, string p_password)
{
Pop3client _ client = new pop3client ();
_ Client. Username = p_name;
_ Client. Password = p_password;
_ Client. Client = new tcpclient ();
_ Client. Client. beginconnect (m_address, m_port, new asynccallback (onconnectrequest), _ client );
While (! _ Client. returnend)
{
System. Windows. Forms. application. doevents ();
}
If (_ client. Error. length! = 0) throw new exception ("error message! "+ _ Client. Error );
Return _ client. maildatatable;
}

/// <Summary>
/// Obtain the email content
/// </Summary>
/// <Param name = "p_name"> name </param>
/// <Param name = "p_password"> password </param>
/// <Param name = "p_mailindex"> email no. </param>
/// <Returns> dataset </returns>
Public datatable getmail (string p_name, string p_password, int p_mailindex)
{
Pop3client _ client = new pop3client ();
_ Client. Username = p_name;
_ Client. Password = p_password;
_ Client. Client = new tcpclient ();
_ Client. readindex = p_mailindex;
_ Client. Client. beginconnect (m_address, m_port, new asynccallback (onconnectrequest), _ client );
While (! _ Client. returnend)
{
System. Windows. Forms. application. doevents ();
}
If (_ client. Error. length! = 0) throw new exception ("error message! "+ _ Client. Error );
Return _ client. mailtable;
}

Private class pop3client
{
Public tcpclient client;

Public String username = "";

Public String Password = "";

Public bool returnend = false;

Public datatable maildatatable = new datatable ();

Public datatable mailtable = new datatable ();

Public string error = "";

Public bool readend = false;

Public int readindex =-1;

Public pop3client ()
{
Maildatatable. Columns. Add ("num ");
Maildatatable. Columns. Add ("size ");
Maildatatable. Columns. Add ("form ");
Maildatatable. Columns. Add ("");
Maildatatable. Columns. Add ("subject ");
Maildatatable. Columns. Add ("date ");

Mailtable. Columns. Add ("type", typeof (string ));
Mailtable. Columns. Add ("text", typeof (object ));
Mailtable. Columns. Add ("name", typeof (string ));
}

Private int m_sendmessage = 0;
Private int m_topindex = 1;

/// <Summary>
/// Obtain the command required for the next login to obtain the list
/// </Summary>
/// <Param name = "p_value"> </param>
/// <Returns> </returns>
Public byte [] getsendbytes (byte [] p_value)
{
Readend = false;
String _ value = system. Text. encoding. Default. getstring (p_value). Replace ("\ 0 ","");
If (_ value. indexof ("+ OK") = 0)
{
M_sendmessage ++;
Switch (m_sendmessage)
{
Case 1:
Return System. Text. encoding. ASCII. getbytes ("user" + username + "\ r \ n ");
Case 2:
Return System. Text. encoding. ASCII. getbytes ("pass" + password + "\ r \ n ");
Case 3:
Readend = true;
If (readindex! =-1)
{
M_sendmessage = 5;
Return System. Text. encoding. ASCII. getbytes ("retr" + readindex. tostring () + "\ r \ n ");
}
Else
{
Return System. Text. encoding. ASCII. getbytes ("list \ r \ n ");
}
Case 4:
String [] _ list = _ value. Split (New char [] {'\ R',' \ n', '.'}, stringsplitoptions. removeemptyentries );
For (INT I = 1; I! = _ List. length; I ++)
{
String [] _ malisize = _ list [I]. Split ('');
Maildatatable. Rows. Add (new object [] {_ malisize [0], _ malisize [1]});
}
If (maildatatable. Rows. Count = 0)
{
Returnend = true;
Return new byte [0];
}
Else
{
Readend = true;
M_topindex = 1;
Return System. Text. encoding. ASCII. getbytes ("Top 1 \ r \ n ");
}
Case 5:
System. Text. regularexpressions. RegEx _ RegEx = new system. Text. regularexpressions. RegEx (@"(? <= Date :).*? (\ R \ n) + ");
System. Text. regularexpressions. matchcollection _ collection = _ RegEx. Matches (_ value );
If (_ collection. Count! = 0) maildatatable. Rows [m_topindex-1] ["date"] = getreadtext (_ Collection [0]. value );

System. Text. regularexpressions. RegEx _ regexfrom = new system. Text. regularexpressions. RegEx (@"(? <= From :).*? (\ R \ n) + ");
System. Text. regularexpressions. matchcollection _ collectionform = _ regexfrom. Matches (_ value );
If (_ collectionform. Count! = 0) maildatatable. Rows [m_topindex-1] ["form"] = getreadtext (_ collectionform [0]. value );

System. Text. regularexpressions. RegEx _ regexto = new system. Text. regularexpressions. RegEx (@"(? <= :).*? (\ R \ n) + ");
System. Text. regularexpressions. matchcollection _ collectionto = _ regexto. Matches (_ value );
If (_ collectionto. Count! = 0) maildatatable. Rows [m_topindex-1] ["to"] = getreadtext (_ collectionto [0]. value );

System. Text. regularexpressions. RegEx _ regexsubject = new system. Text. regularexpressions. RegEx (@"(? <= Subject :).*? (\ R \ n) + ");
System. Text. regularexpressions. matchcollection _ collectionsubject = _ regexsubject. Matches (_ value );
If (_ collectionsubject. Count! = 0) maildatatable. Rows [m_topindex-1] ["subject"] = getreadtext (_ collectionsubject [0]. value );

M_topindex ++;
M_sendmessage --;
Readend = true;
If (m_topindex> maildatatable. Rows. Count)
{
Returnend = true;
Return System. Text. encoding. ASCII. getbytes ("quit ");
}
Else
{
Return System. Text. encoding. ASCII. getbytes ("TOP" + m_topindex.tostring () + "\ r \ n ");
}
Case 6:
Getmailtext (_ value );
Returnend = true;
Return System. Text. encoding. ASCII. getbytes ("quit ");

}
}
Error = _ value;
Returnend = true;
Return new byte [0];
}

/// <Summary>
/// Convert the character set in the text
/// </Summary>
/// <Param name = "p_text"> </param>
/// <Returns> </returns>
Public String getreadtext (string p_text)
{
System. Text. regularexpressions. RegEx _ RegEx = new system. Text. regularexpressions. RegEx (@"(? <=\= \?). *? (\? \ =) + ");
System. Text. regularexpressions. matchcollection _ collection = _ RegEx. Matches (p_text );
String _ text = p_text;
Foreach (system. Text. regularexpressions. Match _ match in _ collection)
{
String _ value = "=? "+ _ Match. value;
If (_ value [0] = ')
{
String [] _ basedata = _ value. Split ('? ');
If (_ basedata. Length = 5)
{
System. Text. Encoding _ coding = system. Text. encoding. getencoding (_ basedata [1]);
_ Text = _ text. Replace (_ value, _ coding. getstring (convert. frombase64string (_ basedata [3]);
}
}
Else
{
}
}
Return _ text;
}

# Region
/// <Summary>
/// Obtain the text subject
/// </Summary>
/// <Param name = "p_mail"> </param>
/// <Returns> </returns>
Public void getmailtext (string p_mail)
{
String _ converttype = gettexttype (p_mail, "\ r \ ncontent-type :",";");
If (_ converttype. Length = 0)
{
_ Converttype = gettexttype (p_mail, "\ r \ ncontent-type:", "\ r ");
}
Int _ starindex =-1;
Int _ endindex =-1;
String _ returntext = "";
String _ transfer = "";
String _ boundary = "";
String _ encodingname = gettexttype (p_mail, "charset = \" "," \ ""). Replace ("\"","");
System. Text. Encoding _ encoding = system. Text. encoding. default;
If (_ encodingname! = "") _ Encoding = system. Text. encoding. getencoding (_ encodingname );
Switch (_ converttype)
{
Case "text/html ;":
_ Transfer = gettexttype (p_mail, "\ r \ ncontent-transfer-encoding:", "\ r \ n"). Trim ();
_ Starindex = p_mail.indexof ("\ r \ n ");
If (_ starindex! =-1) _ returntext = p_mail.substring (_ starindex, p_mail.length-_ starindex );
Switch (_ transfer)
{
Case "8bit ":

Break;
Case "quoted-printable ":
_ Returntext = decodequotedprintable (_ returntext, _ encoding );
Break;
Case "base64 ":
_ Returntext = decodebase64 (_ returntext, _ encoding );
Break;
}
Mailtable. Rows. Add (new object [] {"text/html", _ returntext });
Break;
Case "text/plain ;":
_ Transfer = gettexttype (p_mail, "\ r \ ncontent-transfer-encoding:", "\ r \ n"). Trim ();
_ Starindex = p_mail.indexof ("\ r \ n ");
If (_ starindex! =-1) _ returntext = p_mail.substring (_ starindex, p_mail.length-_ starindex );
Switch (_ transfer)
{
Case "8bit ":

Break;
Case "quoted-printable ":
_ Returntext = decodequotedprintable (_ returntext, _ encoding );
Break;
Case "base64 ":
_ Returntext = decodebase64 (_ returntext, _ encoding );
Break;
}
Mailtable. Rows. Add (new object [] {"text/plain", _ returntext });
Break;
Case "multipart/alternative ;":
_ Boundary = gettexttype (p_mail, "boundary = \" "," \ ""). Replace ("\"","");
_ Starindex = p_mail.indexof ("--" + _ boundary + "\ r \ n ");
If (_ starindex =-1) return;
While (true)
{
_ Endindex = p_mail.indexof ("--" + _ boundary, _ starindex + _ boundary. Length );
If (_ endindex =-1) break;
Getmailtext (p_mail.substring (_ starindex, _ endindex-_ starindex ));
_ Starindex = _ endindex;
}
Break;
Case "multipart/mixed ;":
_ Boundary = gettexttype (p_mail, "boundary = \" "," \ ""). Replace ("\"","");
_ Starindex = p_mail.indexof ("--" + _ boundary + "\ r \ n ");
If (_ starindex =-1) return;
While (true)
{
_ Endindex = p_mail.indexof ("--" + _ boundary, _ starindex + _ boundary. Length );
If (_ endindex =-1) break;
Getmailtext (p_mail.substring (_ starindex, _ endindex-_ starindex ));
_ Starindex = _ endindex;
}
Break;
Default:
If (_ converttype. indexof ("application/") = 0)
{
_ Starindex = p_mail.indexof ("\ r \ n ");
If (_ starindex! =-1) _ returntext = p_mail.substring (_ starindex, p_mail.length-_ starindex );
_ Transfer = gettexttype (p_mail, "\ r \ ncontent-transfer-encoding:", "\ r \ n"). Trim ();
String _ name = gettexttype (p_mail, "filename = \" "," \ ""). Replace ("\"","");
_ Name = getreadtext (_ name );
Byte [] _ filebytes = new byte [0];
Switch (_ transfer)
{
Case "base64 ":
_ Filebytes = convert. frombase64string (_ returntext );
Break;
}
Mailtable. Rows. Add (new object [] {"application/octet-stream", _ filebytes, _ name });

}
Break;
}
}

/// <Summary>
/// Obtain the type (regular)
/// </Summary>
/// <Param name = "p_mail"> original text </param>
/// <Param name = "p_typetext"> prefix text </param>
/// <Param name = "p_end"> end text </param>
/// <Returns> matched records </returns>
Public String gettexttype (string p_mail, string p_typetext, string p_end)
{
System. Text. regularexpressions. RegEx _ RegEx = new system. Text. regularexpressions. RegEx (@"(? <= "+ P_typetext + ").*? ("+ P_end +") + ");
System. Text. regularexpressions. matchcollection _ collection = _ RegEx. Matches (p_mail );
If (_ collection. Count = 0) Return "";
Return _ Collection [0]. value;
}

/// <Summary>
/// Quotedprintable Encoding
/// </Summary>
/// <Param name = "p_text"> original text </param>
/// <Param name = "p_encoding"> encoding method </param>
/// <Returns> post-code information </returns>
Public String decodequotedprintable (string p_text, system. Text. Encoding p_encoding)
{
System. Io. memorystream _ stream = new system. Io. memorystream ();
Char [] _ charvalue = p_text.tochararray ();
For (INT I = 0; I! = _ Charvalue. length; I ++)
{
Switch (_ charvalue [I])
{
Case '= ':
If (_ charvalue [I + 1] = '\ R' | _ charvalue [I + 1] =' \ n ')
{
I + = 2;
}
Else
{
Try
{
_ Stream. writebyte (convert. tobyte (_ charvalue [I + 1]. tostring () + _ charvalue [I + 2]. tostring (), 16 ));
I + = 2;
}
Catch
{
_ Stream. writebyte (convert. tobyte (_ charvalue [I]);
}
}
Break;
Default:
_ Stream. writebyte (convert. tobyte (_ charvalue [I]);
Break;
}
}
Return p_encoding.getstring (_ stream. toarray ());
}

/// <Summary>
/// Decodes base64
/// </Summary>
/// <Param name = "p_text"> </param>
/// <Param name = "p_encoding"> </param>
/// <Returns> </returns>
Public String decodebase64 (string p_text, system. Text. Encoding p_encoding)
{
If (p_text.trim (). Length = 0) Return "";
Byte [] _ valuebytes = convert. frombase64string (p_text );
Return p_encoding.getstring (_ valuebytes );
}
# Endregion

}

/// <Summary>
/// Connection event
/// </Summary>
/// <Param name = "Ar"> </param>
Private void onconnectrequest (iasyncresult AR)
{
Pop3client _ client = (pop3client) Ar. asyncstate;
Byte [] _ readbytes = new byte [0];
_ Client. Client. Client. beginreceive (_ readbytes, 0, 0, socketflags. None, new asynccallback (onwrite), _ client );
}

///

// connection event
///
///
private void onsend (iasyncresult AR)
{< br> pop3client _ client = (pop3client) ar. asyncstate;
byte [] _ readbytes = new byte [0];
_ client. client. client. beginreceive (_ readbytes, 0, 0, socketflags. none, new asynccallback (onwrite), _ client);
}

///

// connection event
///
///
private void onwrite (iasyncresult AR)
{< br> pop3client _ client = (pop3client) ar. asyncstate;
byte [] _ writebytes = new byte [_ client. client. client. receivebuffersize];
_ client. client. client. receive (_ writebytes);
If (_ client. readend) _ writebytes = readend (_ writebytes, _ client);
byte [] _ sendbytes = _ client. getsendbytes (_ writebytes);
If (_ sendbytes. length = 0) return;
_ client. client. client. beginsend (_ sendbytes, 0, _ sendbytes. length, socketflags. none, new asynccallback (onsend), _ client);
}

/// <Summary>
/// Obtain the data. Otherwise, the data is always obtained.
/// </Summary>
/// <Param name = "p_value"> </param>
/// <Returns> </returns>
Private byte [] readend (byte [] p_value, pop3client p_client)
{
If (system. Text. encoding. ASCII. getstring (p_value). indexof ("\ r \ n. \ r \ n ")! =-1) return p_value;
Memorystream _ stream = new memorystream ();
_ Stream. Write (p_value, 0, p_value.length );
While (true)
{
Byte [] _ writebytes = new byte [p_client.client.receivebuffersize];
P_client.client.client.receive (_ writebytes );
_ Stream. Write (_ writebytes, 0, _ writebytes. Length );
System. Threading. thread. Sleep (100 );
If (system. Text. encoding. ASCII. getstring (_ writebytes). indexof ("\ r \ n. \ r \ n ")! =-1) return _ stream. toarray ();
}
}

}
}