zeek/scripts/base/protocols/ftp/file-extract.bro

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##! File extraction for FTP.
@load ./main
@load base/utils/files
module FTP;
export {
## Pattern of file mime types to extract from FTP entity bodies.
const extract_file_types = /NO_DEFAULT/ &redef;
## The on-disk prefix for files to be extracted from FTP-data transfers.
const extraction_prefix = "ftp-item" &redef;
}
redef record Info += {
## The file handle for the file to be extracted
extraction_file: file &log &optional;
extract_file: bool &default=F;
num_extracted_files: count &default=0;
};
event file_transferred(c: connection, prefix: string, descr: string,
mime_type: string) &priority=3
{
local id = c$id;
if ( [id$resp_h, id$resp_p] !in ftp_data_expected )
return;
local s = ftp_data_expected[id$resp_h, id$resp_p];
if ( extract_file_types in s$mime_type )
{
s$extract_file = T;
add s$tags["extracted_file"];
++s$num_extracted_files;
}
}
event file_transferred(c: connection, prefix: string, descr: string,
mime_type: string) &priority=-4
{
local id = c$id;
if ( [id$resp_h, id$resp_p] !in ftp_data_expected )
return;
local s = ftp_data_expected[id$resp_h, id$resp_p];
if ( s$extract_file )
{
local suffix = fmt("%d.dat", s$num_extracted_files);
local fname = generate_extraction_filename(extraction_prefix, c, suffix);
s$extraction_file = open(fname);
if ( s$passive )
set_contents_file(id, CONTENTS_RESP, s$extraction_file);
else
set_contents_file(id, CONTENTS_ORIG, s$extraction_file);
}
}
event log_ftp(rec: Info) &priority=-10
{
delete rec$extraction_file;
delete rec$extract_file;
}