This is a bit shorter and a lot safer.
Substrings of unescaped characters are added by a single call to reduce
overhead.
Extend test 1465 to handle more kind of escapes.
Closes#9653
C string hexadecimal-escaped characters may have more than 2 digits.
This results in a wrong C compiler interpretation of a 2-digit escaped
character when followed by an hex digit character.
The solution retained here is to represent such characters as 3-digit
octal escapes.
Adjust and extend test 1465 for this case.
Closes#9643
The command line tool also independently sets --ftp-skip-pasv-ip by
default.
Ten test cases updated to adapt the modified --libcurl output.
Bug: https://curl.se/docs/CVE-2020-8284.html
CVE-2020-8284
Reported-by: Varnavas Papaioannou
