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113 lines
3.4 KiB
Text
113 lines
3.4 KiB
Text
##! File extraction and introspection for DCC transfers over IRC.
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##!
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##! There is a major problem with this script in the cluster context because
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##! we might see A send B a message that a DCC connection is to be expected,
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##! but that connection will actually be between B and C which could be
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##! analyzed on a different worker.
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##!
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##! Example line from IRC server indicating that the DCC SEND is about to start:
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##! PRIVMSG my_nick :^ADCC SEND whateverfile.zip 3640061780 1026 41709^A
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@load irc/base
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module IRC;
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export {
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redef enum Tag += { EXTRACTED_FILE };
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## Pattern of file mime types to extract from IRC DCC file transfers.
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const extract_file_types = /NO_DEFAULT/ &redef;
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## The on-disk prefix for files to be extracted from IRC DCC file transfers.
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const extraction_prefix = "irc-dcc-item" &redef;
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redef record Info += {
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dcc_file_name: string &log &optional;
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dcc_file_size: count &log &optional;
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dcc_mime_type: string &log &optional;
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## The file handle for the file to be extracted
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extraction_file: file &log &optional;
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## A boolean to indicate if the current file transfer should be extraced.
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extract_file: bool &default=F;
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## The count of the number of file that have been extracted during the session.
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num_extracted_files: count &default=0;
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};
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}
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global dcc_expected_transfers: table[addr, port] of Info = table();
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event file_transferred(c: connection, prefix: string, descr: string,
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mime_type: string) &priority=3
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{
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local id = c$id;
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if ( [id$resp_h, id$resp_p] !in dcc_expected_transfers )
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return;
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local irc = dcc_expected_transfers[id$resp_h, id$resp_p];
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irc$dcc_mime_type = mime_type;
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if ( extract_file_types in mime_type )
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{
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irc$extract_file = T;
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add irc$tags[EXTRACTED_FILE];
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local suffix = fmt("%d.dat", ++irc$num_extracted_files);
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local fname = generate_extraction_filename(extraction_prefix, c, suffix);
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irc$extraction_file = open(fname);
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}
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}
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event file_transferred(c: connection, prefix: string, descr: string,
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mime_type: string) &priority=-4
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{
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local id = c$id;
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if ( [id$resp_h, id$resp_p] !in dcc_expected_transfers )
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return;
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local irc = dcc_expected_transfers[id$resp_h, id$resp_p];
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if ( irc$extract_file && irc?$extraction_file )
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set_contents_file(id, CONTENTS_RESP, irc$extraction_file);
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# Delete these values in case another DCC transfer
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# happens during the IRC session.
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delete irc$extract_file;
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delete irc$extraction_file;
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delete irc$dcc_file_name;
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delete irc$dcc_file_size;
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delete irc$dcc_mime_type;
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delete dcc_expected_transfers[id$resp_h, id$resp_p];
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}
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event irc_server(c: connection, prefix: string, data: string) &priority=5
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{
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local parts = split_all(data, / /);
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local command = parts[1];
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if ( command == "PRIVMSG" &&
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/[dD][cC][cC] [sS][eE][nN][dD]/ in data &&
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|parts| > 12 &&
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/^[0-9]*$/ == parts[|parts|-4] &&
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/^[0-9]*$/ == parts[|parts|-2] )
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{
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c$irc$command = "DCC SEND";
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local ex_h = count_to_v4_addr(extract_count(parts[|parts|-4]));
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local ex_p = to_port(to_count(parts[|parts|-2]), tcp);
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c$irc$dcc_file_name = parts[|parts|-6];
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c$irc$dcc_file_size = extract_count(parts[|parts|]);
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expect_connection(c$id$orig_h, ex_h, ex_p, ANALYZER_FILE, 5 min);
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dcc_expected_transfers[ex_h, ex_p] = c$irc;
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}
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}
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event expected_connection_seen(c: connection, a: count) &priority=10
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{
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local id = c$id;
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if ( [id$resp_h, id$resp_p] in dcc_expected_transfers )
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add c$service["irc-dcc-data"];
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}
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