zeek/scripts/base/utils/strings.bro
2013-03-06 13:45:42 -08:00

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##! Functions to assist with small string analysis and manipulation that can
##! be implemented as Bro functions and don't need to be implemented as built
##! in functions.
## Returns true if the given string is at least 25% composed of 8-bit
## characters.
function is_string_binary(s: string): bool
{
return |gsub(s, /[\x00-\x7f]/, "")| * 100 / |s| >= 25;
}
## Joins a set of string together, with elements delimited by a constant string.
## ss: a set of strings to join
## j: the string used to join set elements
## Returns: a string composed of the all elements of the set, delimited by the
## joining string.
function join_string_set(ss: set[string], j: string): string
{
local output="";
local i=0;
for ( s in ss )
{
if ( i > 0 )
output = cat(output, j);
output = cat(output, s);
++i;
}
return output;
}
## Given a string, returns an escaped version.
## s: a string to escape
## chars: a string containing all the characters that need to be escaped
## Returns: a string with all occurrences of any character in ``chars`` escaped
## using ``\``, and any literal ``\`` characters likewise escaped.
function string_escape(s: string, chars: string): string
{
s = subst_string(s, "\\", "\\\\");
for ( c in chars )
s = subst_string(s, c, cat("\\", c));
return s;
}
## Cut a number of character from the end of the given string.
## s: a string to trim
## tail_len: the number of characters to remove from end of string
## Returns: the string in ``s`` with ``tail_len`` characters removed from end
function cut_tail(s: string, tail_len: count): string
{
if ( tail_len > |s| )
tail_len = |s|;
return sub_bytes(s, 1, int_to_count(|s| - tail_len));
}