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Hi,

I found a small bash script to do exactly what I need but I tweaked a few things. Now I've realised I need this in PHP instead.

Would anyone mind helping me convert this to PHP please? I've done some parts, but with the "==" parts I'm not sure how that works out.

PHP
ssrc=$(tshark -n -r pcap_filename_here -R rtp -T fields -e rtp.ssrc -Eseparator=, | sort -u | awk 'FNR ==1{print}')
echo $ssrc

sudo tshark -n -r pcap_filename_here -R rtp -R "rtp.ssrc == $ssrc" -T fields -e rtp.payload | tee payloads

for payload in `cat payloads`; do IFS=:; for byte in $payload;
do printf "\\x$byte" >> output.raw; done;
done

sox -t raw -r 8000 -v 4 -c 1 -e a-law output.raw output.wav



PHP
<?php

$filename = $_GET['filename'];

exec("tshark -n -r $filename -R rtp -T fields -e rtp.ssrc -E separator=, | sort -u | awk 'FNR ==1{print}'", $ssrc);

echo $ssrc;

exec("sudo tshark -n -r $filename -R rtp -R "rtp.ssrc == $ssrc" -T fields -e rtp.payload | tee payloads");

# unsure how to do this loop

exec('sox -t raw -r 8000 -v 4 -c 1 -e a-law output.raw output.wav');

?>


What I have tried:

--------------------------------------------------------------------------------
Posted
Updated 4-Apr-18 23:28pm
v2
Comments
Richard MacCutchan 5-Apr-18 4:57am    
Why not just 'exec' the entire bash script?
[no name] 5-Apr-18 5:00am    
Although I didn't think of that, I need to add some things to the script which I don't know how to do in bash, as I'm much more experienced with php. Also that would require an additional php file to exec.

1 solution

When you need to include a double quote within a string, you have to escape it as described at PHP: Strings - Manual[^]:
PHP
exec("sudo tshark -n -r $filename -R rtp -R \"rtp.ssrc == $ssrc\" -T fields -e rtp.payload | tee payloads");

The for loop requires understanding the bash commands:
The for loop is a little bit different from other programming languages. Basically, it let's you iterate over a series of 'words' within a string.
So the outer loop will iterate over the white space separated words of the text file payloads and store them in the variable $payload (cat payloads prints the content of text files).

The characters used to detect word boundaries are stored in the $IFS variable (see Advanced Bash-Scripting Guide: Chapter 9. Another Look at Variables[^]). So IFS=: changes this from white spaces to the colon character. The inner for loop splits $payload into : separated words and store them in $byte. That is printed out with a "\x" prefix to the file output.raw.

What the loop finally does is converting a text file with colon separated hex byte values to C style notation skipping all white spaces. Example:
Input : 01:ff:3a:4c 5B:88\n 99:43
Output: \x01\xff\x3a\x4c\x5B\x88\x99\x43
 
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