I am using a PDU generator I found from github and everything works fine when generating simple 7bit character messages.
The issue is that I want to send Unicode characters in 16bit mode and I have to input a char message of hex values in UTF-16BE format split into two characters for each Unicode character like so.
Say an Unicode character of 'Ė' will translate to U+0116 in Unicode and to '\x01\x16' in my program.
I am using this format based on an example from the github repo.
char* message = "\x01\x01\x01\x16"; // Output message will translate to 'āĖ' and is working fine
However inputting a character which would contain a hex value of '\x00' will ignore the rest of the message like so.
char* message = "\x01\x01\x01\x16\x00\x41\x00\x42\x00\x43"; // Output message will translate to 'āĖ'
// when decoded but should instead contain 'āĖABC'
I tried to look around for a solution with no success, here are some parts of the encoding function which seems to generate the PDU message.
void make_pdu(char* number, char* message, int messagelen, int alphabet, int flash_sms, int report, int with_udh,
char* udh_data, char* mode, char* pdu, int validity, int replace_msg, int system_msg, int number_type)
{
int coding;
int flags;
char tmp[50];
char tmp2[500];
int numberformat;
int numberlength;
char *p;
int l;
...
if (alphabet == 1)
coding = 4; // 8bit binary
else if (alphabet == 2)
coding = 8; // 16bit <THE OPTION I USE>
else
coding = 0; // 7bit
if (flash_sms > 0)
coding += 0x10; // Bits 1 and 0 have a message class meaning (class 0, alert)
/* Create the PDU string of the message */
if (alphabet==1 || alphabet==2 || system_msg) // THE OPTION I USE
{
...
binary2pdu(message,messagelen,tmp2);
}
else
messagelen=text2pdu(message,messagelen,tmp2,udh_data);
/* concatenate the first part of the PDU string */
if (strcmp(mode,"old")==0)
sprintf(pdu,"%02X00%02X%02X%s00%02X%02X",flags,numberlength,numberformat,tmp,coding,messagelen);
else // THE OPTION I USE
{
...
sprintf(pdu, "00%02X00%02X%02X%s%02X%02X%02X%02X", flags, numberlength, numberformat, tmp, proto, coding, validity, messagelen);
}
/* concatenate the text to the PDU string */
strcat(pdu,tmp2);
}
/* Converts binary to PDU string, this is basically a hex dump. */
void binary2pdu(char* binary, int length, char* pdu)
{
int character;
char octett[10];
if (length>maxsms_binary)
length=maxsms_binary;
pdu[0]=0;
for (character=0;character<length; character++)
{
//printf("Beep\n");
sprintf(octett,"%02X",(unsigned char) binary[character]);
strcat(pdu,octett);
}
}
As pointed by MikeCAT, the value of \x00 means the end of string. I have been using strlen() to specity the length of the string which was the problem. Tracking the correct length of the message solved the problem.