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Re: Help Reading from a POP3 Mail Server




On 07 Dec 2018, at 09:44, Sam Hobbs <Sam@xxxxxxxxxxxxxxxxxx> wrote:


> Tim Streater wrote:

>> You need to rtrim() each input line, and stop when you find a line

>> consisting of just a full-stop (.)

>

> I think that RFC 1939 (Post Office Protocol - Version 3) and RFC 5322

> (Internet Message Format) are the relevant standards.

>

> RFC 5322 does show examples of commands being sent to the server and the

> responses sent from the server to the client and I do see lines with

> just a period but I don't see documentation of what lines like that mean.


The server will send out such a line when it has finished responding to a command which will generate many lines of response, such as UIDL or RETR. After the last real response line, comes the line just consisting of a . followed by a newline. That should be CR/LF but IME mail servers lie a lot.


If a command has a line-line reply, then it won't send out the dot-line. The programmer has to know which commands return one line, and which don't


There's also the complication of dot-stuffing, since nothing prevents a real data line consisting of a . and nothing else. That is handled by prepending such a dot with another one (or maybe it's any line starting with a dot, can't remember). I found that somewhere in the RFCs.


I do this:


function networkRead ($fp, $where, &$line)

   {


   // Reads a line from the network and does dot-unstuffing.


   $result = netRead ($fp, $line, $errno, $errstr, $where);


   if ($result==false)

     {

     $msg = 'error in networkRead at ' . $where . ': ' . $errno . ' ' . $errstr;

     writeLog ($msg);

     return READ_ERROR;

     }


   if ($line=='.') return READ_EOM;


   if (strlen($line)>1 && $line[0]=='.') $line = substr ($line, 1);


   return READ_OK;


   }



where netRead (...) uses gets() to read a line and check for errors including timeout.





--
Cheers -- Tim