add skrewt to filter-chain

3 files changed, 204 insertions, 2 deletions

diff --git a/tools/filters.conf b/tools/filters.conf
index 97b54d1..2a9e5d0 100644
--- a/tools/filters.conf
+++ b/tools/filters.conf
@@ -1,3 +1,4 @@
 # configuration file for hi-q
+  /var/qmail/bin/skrewt
   /usr/local/bin/spamc -Y 2
   /var/qmail/bin/qmail-queue
diff --git a/tools/makefile b/tools/makefile
index 256fa6e..c5b702b 100644
--- a/tools/makefile
+++ b/tools/makefile
@@ -10,10 +10,12 @@ CC= /usr/bin/g++ -Wall -g -I $(HOME)/lib/include
 
 .SECONDARY : # do not remove any intermediate files
 
-all: pido hi-q
+progs = pido hi-q skrewt
+
+all: $(progs)
 
 install:
-	install pido hi-q /var/qmail/bin/
+	install $(progs) /var/qmail/bin/
 	cp filters.conf   /var/qmail/control/
 	install -m700 -d /var/qmail/rbin
 	chown qmaild /var/qmail/rbin
@@ -27,6 +29,7 @@ install:
 	chown qmaild /var/qmail/control/*.crtkey
 	install qmail-tls-check_certs /var/qmail/bin/
 	install spamassassin /etc/init.d/
+	install qmail /etc/init.d/
 	install spamassassin.default /etc/default/spamassassin
 	install tcprules.make /etc/tcpserver/makefile
 
diff --git a/tools/skrewt.c b/tools/skrewt.c
new file mode 100644
index 0000000..117981b
--- /dev/null
+++ b/tools/skrewt.c
@@ -0,0 +1,198 @@
+///////////////////
+// skrewt.c
+//
+// scrutinize email
+//
+
+#include <iostream>
+#include <stdlib.h>             /* for exit() */
+#include <string>               /* for strcmp() */
+#include <ctype.h>              /* toupper */
+
+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, 1 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"
+"    -h      print this msg (and exit immediately).\n"
+"\n"
+"  Messages containing the string '-please-bounce-this-' will be rejected.\n"
+"  Messages with no date will be rejected.\n"
+;
+  exit(sts);
+}
+
+/////////////////////////////////////////////////////////
+// Case insensitive comparison of strings
+
+class lessthan_foldcase{
+public:
+  bool operator() (const std::string& a, const std::string& b) const {
+    size_t a_len = a.length();
+    size_t b_len = b.length();
+
+    size_t lim = a_len < b_len ? a_len : b_len;
+
+    for (size_t i=0; i<lim; ++i)
+    {
+            char cha = toupper(a[i]);
+            char chb = toupper(b[i]);
+
+            if (cha < chb) return true;
+            if (cha > chb) return false;
+    }
+    // here if one is an extension of the other
+    if ( a_len < b_len ) return true;
+    return false;
+  }
+};
+
+
+// Returns negative if a is less than b in alphabetical order
+// returns 0 if they are the same, or positive if a is greater.
+// Like perl cmp operator, but ignores case.
+int cmp_casefold(const std::string& a, const std::string& b) {
+  string::const_iterator aa, bb;
+  aa = a.begin();
+  bb = b.begin();
+  while (aa != a.end() && bb != b.end()){
+    char ca = tolower(*aa++);
+    char cb = tolower(*bb++);
+    if (ca != cb) return ca < cb ? -2 : 2;
+  }
+  if (aa != a.end()) return 1;          // a is longer
+  if (bb != b.end()) return -1;         // b is longer
+  return 0;
+}
+
+
+string toLower(const std::string& a){
+  string rslt = a;
+  string::iterator rr;
+  for (rr = rslt.begin(); rr != rslt.end(); rr++){
+    *rr = tolower(*rr);
+  }
+  return rslt;
+}
+
+
+string ltrim(string foo){
+  unsigned where = foo.find_first_not_of(" \t\r\n");
+  if (where == foo.npos) return foo;
+  return foo.substr(where);
+}
+
+
+
+int main(int argc, char** argv){
+  if (argc > 1) {
+    if (argv[1] == string("-h")) usage(0);
+    usage(1);
+  }
+
+  int inheads(1);
+  string boundary("x-xx-x");
+  int text_type(1);
+  int textlines(0);
+  int gotdate(0);
+  for (;;){
+    if (cin.eof()) break;
+    if (cin.bad()) return 1;
+    if (inheads) {
+      string header;
+      if (getline(cin, header).fail()) continue;
+      for (;;) {
+        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;
+        if (getline(cin, line).fail()) continue;
+        header += "\n" + line;
+      }
+      if (header.length() == 0) {
+        if (!gotdate) {
+          cerr << "skrewt rejection: no date" << endl;
+          exit(1);              // disallow mail with no date
+        }
+        inheads = 0;
+      }
+      else {
+        string headword;
+        string rest;
+        unsigned int where = header.find(":");
+        if (where != string::npos) {
+          headword = header.substr(0, where);
+          rest = ltrim(header.substr(1+where));
+        }
+        headword = toLower(headword);
+        if (headword == "content-type") {
+          string the_type = rest;
+          unsigned int where = the_type.find_first_of(" \t;\n");
+          if (where == string::npos) {
+            /* do nothing */
+          }
+          else {
+            the_type = the_type.substr(0,where);
+          }
+          the_type = toLower(the_type);
+          text_type = (the_type.find("text/") == 0);
+          if (0) cerr << "type (" << the_type << ")  "
+                << (text_type?"text":"nope") << endl;
+          string srch = "boundary=";
+          where = header.find(srch);
+          if (where != string::npos) {
+            where += srch.length();
+            boundary = header.substr(where);
+            if (boundary[0] == '"') {
+              boundary = boundary.substr(1);
+              where = boundary.find_first_of("\"");
+            } else {
+              where = boundary.find_first_of(" \t;\n");
+            }
+            if (where == string::npos) {
+              /* do nothing, boundary=boundary as a whole */
+            } else {
+              boundary = boundary.substr(0, where);
+            }
+          }
+        } else if (headword == "date") {
+          gotdate++;
+        } else if (headword == "subject") {
+          if (rest.find("-please-bounce-this-") != string::npos) {
+            cerr << "skrewt rejection: by request" << endl;
+            exit(1);
+          }
+        }
+      }
+      cout << header << endl;
+    } else {
+      string line;
+      if (!getline(cin, line).fail()) {
+        if (line == "--" + boundary) {
+          inheads = 1;
+        } else {
+          if (text_type) {
+            if (ltrim(line).length()) textlines++;
+          }
+        }
+        cout << line << endl;
+      }
+    }
+  }
+  if (0) cerr << "textlines: " << textlines << endl;
+  if (!textlines) {
+    cerr << "skrewt rejection: no text" << endl;
+    exit(1);
+  }
+  return 0;
+}