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//////////////////
// skrewt.c
//
// scrutinize email
//
#include <iostream>
#include <stdlib.h> /* for exit() */
#include <string> /* for strcmp() */
#include <ctype.h> /* toupper */
#include <stdio.h> /* perror */
#include <sstream>
#include <vector>
#include <list>
using namespace std;
void usage(const int sts){
(sts ? cerr : cout) <<
"Usage: skrewt [options]\n"
"\n"
" Scrutinizes email. Reads stdin, copies it to stdout.\n"
" Exit result 0 means good, 21 means rejection (spam).\n"
" Writes reason for rejection to stderr.\n"
"\n"
" Typically used as a filter in a pipeline, along with spamc -E\n"
" Options\n"
" -help print this msg (and exit immediately).\n"
" -maxsize ii msg size in bytes; anything bigger will be rejected.\n"
" -error-exit exit early if errors have been detected.\n"
"\n"
" Messages containing the string '-please-bounce-this-' will be rejected.\n"
" Messages with no date will be rejected.\n"
;
exit(sts);
}
#include "libskrewt.h"
#include "utils.h"
string progname, progid;
int mypid;
/* Content-Type: text/plain; charset="us-ascii" */
/* Content-Type: multipart/mixed; boundary="1170861315-1262462055-1341954763=:92165" */
//
#if 0 /* typical "Received: from" lines */
Received: from lists.sourceforge.net (216.34.181.88)
by cloud.av8n.com with SMTP; 31 Jul 2012 22:13:48 -0000
Received: from 24-145-119-127-dhcp.gsv.md.atlanticbb.net (HELO mail.phys-l.org) (24.145.119.127) by cloud.av8n.com with SMTP; 14 Jul 2012 23:56:54 -0000
Received: from ip68-231-191-153.tc.ph.cox.net (HELO asclepias.av8n.net) (smtp@68.231.191.153) by cloud.av8n.com with SMTP; 15 Jul 2012 14:39:58 -0000
#endif
#if 0 /* good for testing */
// random mail from FAA
/home/jsd/Maildir/cur/1343769926.24228.cloud\:2\,
// has a good SPF result buried inside, at an earlier hop:
/home/jsd/Maildir/cur/1342372942.24810.cloud:2,
// has a good SPF as delivered to us:
/home/jsd/Maildir/cur/1343671179.10420.cloud:2,
// The following msg has no message-id, but does have an
// authorized submitter:
/home/jsd/Maildir/cur/1342363199.24320.cloud:2,
#endif
int skrewt::headers(){
//xxxx cerr << progid << " begins" << endl;
for (;;){ // outer loop over all records in the header
if (cin.eof()) break;
if (cin.bad()) return 1;
string line;
// on fail, go back to top of outer loop and check for eof versus bad
if (getline(cin, line).fail()) continue;
msgsize += line.length()+1;
if (msgsize > maxsize) {
cerr << progid << " rejection: bigger than " << maxsize << endl;
exeunt(ex_spam);
}
cout << line << endl;
bigbuf.push_back(line);
string headrec = noCR(line); // for a folded record, this is the first line
for (;;) { // inner loop to build a multi-line record e.g. folded record:
if (cin.eof()) break;
if (cin.bad()) return 1;
char ch;
if (cin.get(ch).fail()) continue;
cin.putback(ch);
if (ch != ' ' && ch != '\t') break;
string line;
// on fail, go back to top of inner loop and check for eof versus bad
if (getline(cin, line).fail()) continue;
msgsize += line.length()+1;
if (msgsize > maxsize) {
cerr << progid << " rejection: bigger than " << maxsize << endl;
exeunt(ex_spam);
}
cout << line << endl;
bigbuf.push_back(line);
headrec += "\n" + noCR(line);
}
// here with a fully assembled header record
// headrec (unlike line) contains no DOS CR characters
int len = headrec.length();
if (len == 0) {
saw_blank_line = 1;
break; // no more headers in this message
}
// here if it's a header line
string headword;
string rest;
size_t where = headrec.find(":");
if (where != string::npos) {
headword = headrec.substr(0, where);
rest = ltrim(headrec.substr(1+where));
}
headword = toLower(headword);
if (0){
} else if (headword == "from") {
from = rest;
} else if (headword == "to") {
to = rest;
} else if (headword == "return-path") {
return_path = rest;
} else if (headword == "message-id") {
message_id = rest;
} else if (headword == "received") {
if (!received_from.length() && prefix("from ", rest)){
received_from = rest;
}
} else if (headword == "date") {
date = rest;
} else if (headword == "subject") {
subject = rest;
} else if (headword == "content-type") {
content_type = rest;
} else if (headword == "delivered-to") {
delivered_to = rest;
}
//xxxx cout << headrec.length() << " ... ";
recno++;
if (0) if (recno <= 6) cerr << progid << "#" << recno
<< " " << headrec << endl;
}
return 0;
}
////////////////////////////////////////////////////////////
int main(int _argc, const char** _argv){
int argc(_argc);
const char **argv(_argv);
{
progname = *argv++; argc--;
mypid = getpid();
stringstream binder;
binder << basename(progname) << "[" << mypid << "]";
progid = binder.str();
}
skrewt mysk;
while (argc) {
string arg(*argv); argv++; argc--;
if (arg.substr(0,2) == "--") arg = arg.substr(1);
if (prefix(arg, "-help")) {
usage(0);
}
if (0) {
} else if (prefix(arg, "-mid-required")) {
mysk.mid_required++;
} else if (prefix(arg, "-error-exit")) {
mysk.error_exit++;
} else if (prefix(arg, "-maxsize")) {
if (!argc) {
cerr << "Option -maxsize requires an argument" << endl;
exit(ex_usage);
}
mysk.maxsize = atoi(*argv); argv++; argc--;
} else if (arg.substr(0,1) == "-") {
cerr << "Unrecognized option '" << arg << "'" << endl;
cerr << "For help, try: " << progname << " -help" << endl;
exit(ex_usage);
} else {
cerr << "Extraneous verbiage '" << arg << "'" << endl;
cerr << "For help, try: " << progname << " -help" << endl;
exit(ex_usage);
}
}
int rslt = mysk.headers();
if (rslt) return rslt;
// Headers are done.
// Do some early-stage thinking.
rslt = mysk.interstage();
if (rslt) return rslt;
rslt = mysk.body();
return rslt;
}
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