如何构建串联的短信 pdu？获取垃圾字符

Posted 2023-03-16

【中文标题】如何构建串联的短信 pdu？获取垃圾字符

【英文标题】：How to build concatenated sms pdu? Getting junk chars

【发布时间】：2012-08-31 04:24:14

【问题描述】：

我正在尝试构建一些 php 代码以通过 telnet 将 SMS 发送到 SIM 服务器，但在发送串联消息时遇到了问题。

我已经阅读了一些关于使用填充位将编码消息 septets 转换为 octets 的内容，但我并不完全理解它是如何工作的。

我有一个类接收电话号码、消息（已拆分为最大 153 个字符）、短信总数和当前文本部分的订单号。

只要我在 $hexmessage 之前添加了“20”，它就可以工作。但是我在第一部分的开头（在我的味精的第一个字母之前）得到了一个垃圾字符，并且相同的垃圾字符替换了第二部分的第一个字母！ （使用 '20' 所以它会显示一个空格，但它会显示一个三角形）

我不明白为什么，或者我必须改变什么才能让它正常工作。

我希望有人能帮助我理解我做错了什么。

这是我目前所得到的：

<?php

 // Generate PDU string
public function generatePDUm($receiverNumber,$message, $sms_count, $msg_nr) 

    //Append filler digit if number is national
    if( strlen($receiverNumber)==9)
        $nacional=1;
        $receiverNumber = $receiverNumber."F";                              
        $network = substr($receiverNumber, 0, 2);                       //NETWORK code, used to decide the SIM Card to be used

    //Check for international flags and set the number type accordingly
    else
        $nacional=0;
        if(substr($receiverNumber, 0, 1)=='+')
            $network = substr($receiverNumber, 4, 2);                   //NETWORK code, used to decide the SIM Card to be used 
            $receiverNumber = substr($receiverNumber, 1, 12);           //remove international indicator    
         
        else if(substr($receiverNumber, 0, 2)== '00')
            $network = substr($receiverNumber, 5, 2);                   //NETWORK code, used to decide the SIM Card to be used 
            $receiverNumber = substr($receiverNumber, 2, 12);           //remove international indicator
        

    

    /* Flag the network to be used */
    switch ($network)
        case  "92":
            $network="TMN";
            break;

        case  "96":
            $network="TMN";
            break;

        case "91":
            $network="VODAFONE";
            break;

        case "93":
            $network="OPTIMUS";
            break;
    
    // Receiver number must be 10 characters long ('national nr' + filler digit) or less than 13 ('351'+'national nr'). (Portugal)
    if( strlen($receiverNumber) < 10 || strlen($receiverNumber) > 12) 
        // Error, not 10 or over 12 numbers long (Code 1)
        $this->setErrorCode(1);
        return false;
    

    // Message must be 2 characters long at least
    if( strlen($message) < 2 ) 
        // Error, message too short (Code 2)
        $this->setErrorCode(2);
        return false;
    

    // Message can't be longer than 153 characters. 3SMS.
    if( strlen($message) > 153 ) 
        // Error, message too long (Code 3)
        $this->setErrorCode(3);
        return false;
    

    // Length of servicecenter number (00 = automatically fixed by phone)
    $serviceCenterNumberLength = '00';

    // SMS-? : 04=sms-deliver(recieve), 11=sms-submit, 01 = dont know but it works, 41 = SMS-SUBMIT + UDH bit (for extended/concatenated SMS)
    // You can try to change this if your phone does not work with 01 command try to use 11 command
    $smsType = '41';

    // TP Message Reference: (placeholder), let the phone set the message reference number itself
    $messageRef = '00';

    // Number length. If national -> 9, if international -> 12
    if($nacional==1)
        $numberLength = '09';
    else
        $numberLength = '0C';
    


    // Type of phone adress: (81=Unknown=10dec, 91=InternationalFormat, 92=National?)
    if($nacional==1)
        $numberType = '81';
    else
        $numberType = '91';
    

    // Get the PDU version of the number
    $number = $this->getNumberAsPDU( $receiverNumber );

    // TP-PID (Protocol Identifier)
    $protocolId = '00';

    // TP-DCS (Data coding scheme)
    $dataCodingScheme = '00';

    // TP-Validity-Period (timestamp), AA=4days expiry, disabled for SonyEricsson support.
   // $validityPeriod = 'A0';
    // $validityPeriod = 'AA'; // Add this if the PDU command fails

    /*user data header information (05 - User Data header info length 
    *                               00 - Information element identifier for a concatenated short message
    *                               03 - Information element data length
    *                               00 - Reference number, auto
    *                               0.$sms_count - total SMS nr
    *                               0.$msg_nr    - current SMS order */
    $udhi = '050003000'.$sms_count.'0'.$msg_nr;
   // echo 'UDHinfo: '.$udhi."\n";

    // Data length of message (in hex format)
    $dataLength = $this->strToHexLen($message);
   // echo 'DATA LENGHT: '.$dataLength."\n\n";

    // Convert message, string > 7bits > 8bits > hex
    $hexMessage = $this->bit7tohex( $this->strto7bit( $message ) );


    // Create the complete PDU string
    $pdu = $serviceCenterNumberLength . $smsType . $messageRef . $numberLength .
            $numberType . $number . $protocolId . $dataCodingScheme . $dataLength .
            $udhi . '20' .$hexMessage;

    /*
     * Generate the length of var $pdu (pdu/2 minus 1) as pdu format requests
     * The -1 is because we don't count the first two characters '00', needed for this command: 'cmgs=24'
     */
    $cmgslen = strlen($pdu)/2-1;

    // Build data array to return with required information
    $data = array();
    $data['pdu'] = $pdu;
    $data['cmgslen'] = $cmgslen;
    $data['rede'] = $network;

    // Return the data array with PDU information
    return $data;



// Generate PDU formatted cellphone number
private function getNumberAsPDU($number) 

        // Length of number divided by 2 handle two characters each time
    $length = strlen( $number )/2;
    // Set counter to 1 for strlen
    $i = 1;
    $pduNumber = '';

    // Loop to handle every 2 characters of the phone number. 06 12 34 56 78
    while ($i <= $length) 
        // Get 2 characters of the complete string depending on the number of the current loop.
        // Then reverse these 2 characters and put them in var $pduNumber (06 = 60)
        $pduNumber .= strrev( substr( $number,$i*2-2,2) );
        // Counter + 1
        $i++;
    

    // Return the generated number
    return $pduNumber;



/* Function to convert ascii character to 8 bits
 * Much more efficient than holding a complete ASCII table
 * Thanks to Mattijs F.
 */
private function asc2bin($input, $length=8) 

    $bin_out = '';
    // Loop through every character in the string
    for($charCount=0; $charCount < strlen($input); $charCount++) 
        $charAscii = ord($input$charCount); // ascii value of character
        $charBinary = decbin($charAscii); // decimal to binary
        $charBinary = str_pad($charBinary, $length, '0', STR_PAD_LEFT);
        $bin_out .= $charBinary;
    

    // Return complete generated string
    return $bin_out;



// String to 7 bits array
private function strto7bit($message) 
    $message = trim($message);
    $length = strlen( $message );
    $i = 1;
    $bitArray = array();

    // Loop through every character in the string
    while ($i <= $length) 
        // Convert this character to a 7 bits value and insert it into the array
        $bitArray[] = $this->asc2bin( substr( $message ,$i-1,1) ,7);
        $i++;
    


    // Return array containing 7 bits values
    return $bitArray;



// Convert 8 bits binary string to hex values (like F2)
private function bit8tohex($bin, $padding=false, $uppercase=true) 
    $hex = '';
    // Last item for counter (for-loop)
    $last = strlen($bin)-1;
    // Loop for every item
    for($i=0; $i<=$last; $i++) 
        $hex += $bin[$last-$i] * pow(2,$i);
    

    // Convert from decimal to hexadecimal
    $hex = dechex($hex);
    // Add a 0 (zero) if there is only 1 value returned, like 'F'
    if($padding && strlen($hex) < 2 ) 
        $hex = '0'.$hex;
    

    // If we want the output returned as UPPERCASE do this
    if($uppercase) 
        $hex = strtoupper($hex);
    

    // Return the hexadecimal value
    return $hex;



// Convert 7 bits binary to hex, 7 bits > 8 bits > hex
private function bit7tohex($bits) 

    $i = 0;
    $hexOutput = '';
    $running = true;

    // For every 7 bits character array item
    while($running) 

        if(count($bits)==$i+1) 
            $running = false;
        

        $value = $bits[$i];

        if($value=='') 
            $i++;
            continue;
        

        // Convert the 7 bits value to the 8 bits value
        // Merge a part of the next array element and a part of the current one

        // Default: new value is current value
        $new = $value;

        if(key_exists(($i+1), $bits)) 
            // There is a next array item so make it 8 bits
            $neededChar = 8 - strlen($value);
            // Get the char;s from the next array item
            $charFromNext = substr($bits[$i+1], -$neededChar);
            // Remove used bit's from next array item
            $bits[$i+1] = substr($bits[$i+1], 0, strlen($bits[$i+1])-$neededChar );
            // New value is characters from next value and current value
            $new = $charFromNext.$value;
        

        if($new!='') 
            // Always make 8 bits
            $new = str_pad($new, 8, '0', STR_PAD_LEFT);
            // The 8 bits to hex conversion
            $hexOutput .= $this->bit8tohex($new, true);
        

        $i++;
    

    // Return the 7bits->8bits->hexadecimal generated value
    return $hexOutput;


// String to length in Hex, String > StringLength > Hex
private function strToHexLen($message) 

    // Length of the string (message)
    $length = strlen( $message )+7; //+7 for UDH. the UDH is a total of (number of octets x bit size of octets) 6 x 8 = 48 bits long. Therefore a single bit of padding has to be prepended to the message. The UDH is therefore (bits for UDH / bits per septet) = (48 + 1)/7 = 7 septets in length.
    // Hex value of this string length
    $hex = dechex($length);

    // Length of the hex value
    $hexLength = strlen($hex);
    // If the hex strng length is lower dan 2
    if($hexLength < 2) 
        // Add a 0 (zero) before it
        $hex = '0'.$hex;
    

    // Return the hex value in UPPERCASE characters
    return strtoupper($hex);



?>

【参考方案1】：

如您所知，创建串联的 SMS 消息需要您在文本消息之前添加 UDH。 UDH 成为您有效负载的一部分，从而减少了您可以在每个段中发送的字符数。

由于它已成为您有效负载的一部分，因此需要确认您的有效负载数据要求 - 即 7 位。然而，UDH 是 8 位的，这显然使事情变得复杂。

考虑以下的UDH：

050003000302

05是UDH的长度 00 是 IEI 03 是 IEDL（另外 3 个八位字节） 00 是一个参考（这个数字在你的每个连接的消息 UDH 中必须相同） 03 是消息的最大数量 02 是当前消息号。

总共有 6 个八位字节 - 相当于 48 位。这一切都很好，但是由于 UDH 实际上是您的 SMS 消息的一部分，您需要做的是添加更多位，以便实际消息从 septet 边界开始。每 7 位有一个 septet 边界，因此在这种情况下，我们必须再添加 1 位数据以使 UDH 为 49 位，然后我们可以添加我们的标准 GSM-7 编码字符。

您可以从Here 阅读更多相关信息

【参考方案2】：

这些问题无处不在，似乎没有人能够以任何有意义的方式回答它们。零填充通常只会让事情变得更糟。我认为解决 GMS 标准中这个设计缺陷的最简单方法是使用 8 位编码或 16 位 UCS2，即使这意味着更少的字符。这样您就无需关心字节边界的差异，这就是创建串联 SMS 如此困难的原因。