#!/usr/bin/env python
# -*- mode: python -*-
import userdir_gpg, userdir_ldap, sys, traceback, time, ldap, os;
import string, pwd
from userdir_gpg import *;
from userdir_ldap import *;

# Error codes from /usr/include/sysexits.h
ReplyTo = ConfModule.replyto;
PingFrom = ConfModule.pingfrom;
ChPassFrom = ConfModule.chpassfrom;
ChangeFrom = ConfModule.changefrom;
ReplayCacheFile = ConfModule.replaycachefile;

EX_TEMPFAIL = 75;
EX_PERMFAIL = 65;      # EX_DATAERR
Error = 'Message Error';
SeenRSA = 0;
SeenDSA = 0;
SeenDNS = 0;

ArbChanges = {"c": "..",
	      "l": ".*",
	      "facsimiletelephonenumber": ".*",
	      "telephonenumber": ".*",
	      "postaladdress": ".*",
	      "postalcode": ".*",
              "loginshell": ".*",
              "emailforward": "^([^<>@]+@.+)?$",
              "ircnick": ".*",
              "icquin": "^[0-9]*$",
              "onvacation": ".*",
              "labeledurl": ".*"};

DelItems = {"c": None,
            "l": None,
            "facsimiletelephonenumber": None,
            "telephonenumber": None,
            "postaladdress": None,
            "postalcode": None,
            "emailforward": None,
            "ircnick": None,
            "onvacation": None,
            "labeledurl": None,
	    "latitude": None,
	    "longitude": None,
            "icquin": None,
	    "sshrsaauthkey": None,
	    "sshdsaauthkey": None};

# Decode a GPS location from some common forms
def LocDecode(Str,Dir):
   # Check for Decimal degrees, DGM, or DGMS
   if re.match("^[+-]?[\d.]+$",Str) != None:
      return Str;

   Deg = '0'; Min = None; Sec = None; Dr = Dir[0];
   
   # Check for DDDxMM.MMMM where x = [nsew]
   Match = re.match("^(\d+)(["+Dir+"])([\d.]+)$",Str);
   if Match != None:
      G = Match.groups();
      Deg = G[0]; Min = G[2]; Dr = G[1];

   # Check for DD.DD x 
   Match = re.match("^([\d.]+) ?(["+Dir+"])$",Str);
   if Match != None:
      G = Match.groups();
      Deg = G[0]; Dr = G[1];

   # Check for DD:MM.MM x 
   Match = re.match("^(\d+):([\d.]+) ?(["+Dir+"])$",Str);
   if Match != None:
      G = Match.groups();
      Deg = G[0]; Min = G[1]; Dr = G[2];

   # Check for DD:MM:SS.SS x
   Match = re.match("^(\d+):(\d+):([\d.]+) ?(["+Dir+"])$",Str);
   if Match != None:
      G = Match.groups();
      Deg = G[0]; Min = G[1]; Sec = G[2]; Dr = G[3];
      
   # Some simple checks
   if float(Deg) > 180:
      raise "Failed","Bad degrees";
   if Min != None and float(Min) > 60:
      raise "Failed","Bad minutes";
   if Sec != None and float(Sec) > 60:
      raise "Failed","Bad seconds";
      
   # Pad on an extra leading 0 to disambiguate small numbers
   if len(Deg) <= 1 or Deg[1] == '.':
      Deg = '0' + Deg;
   if Min != None and (len(Min) <= 1 or Min[1] == '.'):
      Min = '0' + Min;
   if Sec != None and (len(Sec) <= 1 or Sec[1] == '.'):
      Sec = '0' + Sec;
   
   # Construct a DGM/DGMS type value from the components.
   Res = "+"
   if Dr == Dir[1]:
      Res = "-";
   Res = Res + Deg;
   if Min != None:
      Res = Res + Min;
   if Sec != None:
      Res = Res + Sec;
   return Res;
	      
# Handle changing a set of arbitary fields
#  <field>: value
def DoArbChange(Str,Attrs):
   Match = re.match("^([^ :]+): (.*)$",Str);
   if Match == None:
      return None;
   G = Match.groups();
   
   if ArbChanges.has_key(G[0]) == 0:
      return None;
      
   if re.match(ArbChanges[G[0]],G[1]) == None:
      raise Error, "Item does not match the required format"+ArbChanges[G[0]];

   Attrs.append((ldap.MOD_REPLACE,G[0],G[1]));
   return "Changed entry %s to %s"%(G[0],G[1]);

# Handle changing a set of arbitary fields
#  <field>: value
def DoDel(Str,Attrs):
   Match = re.match("^del (.*)$",Str);
   if Match == None:
      return None;
   G = Match.groups();
 
   if DelItems.has_key(G[0]) == 0:
      return "Cannot erase entry %s"%(G[0]);

   Attrs.append((ldap.MOD_DELETE,G[0],None));
   return "Removed entry %s"%(G[0]);

# Handle a position change message, the line format is:
#  Lat: -12412.23 Long: +12341.2342
def DoPosition(Str,Attrs):
   Match = re.match("^lat: ([+\-]?[\d:.ns]+(?: ?[ns])?) long: ([+\-]?[\d:.ew]+(?: ?[ew])?)$",string.lower(Str));
   if Match == None:
      return None;

   G = Match.groups();
   try:
      sLat = LocDecode(G[0],"ns");
      sLong = LocDecode(G[1],"ew");
      Lat = DecDegree(sLat,1);
      Long = DecDegree(sLong,1);
   except:
      raise Error, "Positions were found, but they are not correctly formed";

   Attrs.append((ldap.MOD_REPLACE,"latitude",sLat));
   Attrs.append((ldap.MOD_REPLACE,"longitude",sLong));
   return "Position set to %s/%s (%s/%s decimal degrees)"%(sLat,sLong,Lat,Long);

# Handle a SSH RSA authentication key, the line format is:
#  [options] 1024 35 13188913666680[..] [comment]
def DoSSH(Str,Attrs):
   Match = SSHAuthSplit.match(Str);
   if Match == None:
      return None;
   
   global SeenRSA;
   if SeenRSA:
     Attrs.append((ldap.MOD_ADD,"sshrsaauthkey",Str));
     return "SSH Key added "+FormatSSHAuth(Str);
      
   Attrs.append((ldap.MOD_REPLACE,"sshrsaauthkey",Str));
   SeenRSA = 1;
   return "SSH Keys replaced with "+FormatSSHAuth(Str);

# Handle a SSH DSA authentication key, the line format is:
#  ssh-dss [key] [comment]
def DoSSH2(Str,Attrs):
   Match = SSHDSAAuthSplit.match(Str);
   if Match == None:
      return None;

   global SeenDSA;
   if SeenDSA:
     Attrs.append((ldap.MOD_ADD,"sshdsaauthkey",Str));
     return "SSH2 Key added "+FormatSSH2Auth(Str);
      
   Attrs.append((ldap.MOD_REPLACE,"sshdsaauthkey",Str));
   SeenDSA = 1;
   return "SSH2 Keys replaced with "+FormatSSH2Auth(Str);

# Handle changing a dns entry
#  host in a 12.12.12.12
#  host in cname foo.bar.    <- Trailing dot is required
def DoDNS(Str,Attrs,DnRecord):
   if re.match('^[\w-]+\s+in\s+a\s+\d{1,3}\.\d{1,3}\.\d{1,3}\.\d{1,3}$',\
        Str,re.IGNORECASE) == None and \
      re.match("^[\w-]+\s+in\s+cname\s+[\w.\-]+\.$",Str,re.IGNORECASE) == None and \
      re.match("^[\w-]+\s+in\s+mx\s+\d{1,3}\s+[\w.\-]+\.$",Str,re.IGNORECASE) == None:
     return None;     

   # Check if the name is already taken
   G = re.match('^([\w-+]+)\s',Str).groups();

   # Check for collisions
   global l;
   Rec = l.search_s(BaseDn,ldap.SCOPE_ONELEVEL,"dnszoneentry="+G[0]+" *",["uid"]);
   for x in Rec:
      if GetAttr(x,"uid") != GetAttr(DnRecord,"uid"):
         return "DNS entry is already owned by " + GetAttr(x,"uid")

   global SeenDNS;
   if SeenDNS:
     Attrs.append((ldap.MOD_ADD,"dnszoneentry",Str));
     return "DNS Entry added "+Str;
      
   Attrs.append((ldap.MOD_REPLACE,"dnszoneentry",Str));
   SeenDNS = 1;
   return "DNS Entry replaced with "+Str;

# Handle an [almost] arbitary change
def HandleChange(Reply,DnRecord,Key):
   global PlainText;
   Lines = re.split("\n *\r?",PlainText);

   Result = "";
   Attrs = [];
   Show = 0;
   for Line in Lines: 
      Line = string.strip(Line);
      if Line == "":
         continue;

      # Try to process a command line
      Result = Result + "> "+Line+"\n";
      try:
         if Line == "show":
           Show = 1;
	   Res = "OK";
         else:
           Res = DoPosition(Line,Attrs) or DoDNS(Line,Attrs,DnRecord) or \
                 DoArbChange(Line,Attrs) or DoSSH(Line,Attrs) or \
		 DoSSH2(Line,Attrs) or DoDel(Line,Attrs);
      except:
         Res = None;
         Result = Result + "==> %s: %s\n" %(sys.exc_type,sys.exc_value);
	 
      # Fail, if someone tries to send someone elses signed email to the
      # daemon then we want to abort ASAP.
      if Res == None:
         Result = Result + "Command is not understood. Halted\n";
         break;
      Result = Result + Res + "\n";

   # Connect to the ldap server
   l = ldap.open(LDAPServer);
   F = open(PassDir+"/pass-"+pwd.getpwuid(os.getuid())[0],"r");
   AccessPass = string.split(string.strip(F.readline())," ");
   F.close();

   # Modify the record
   l.simple_bind_s("uid="+AccessPass[0]+","+BaseDn,AccessPass[1]);
   Dn = "uid=" + GetAttr(DnRecord,"uid") + "," + BaseDn;
   l.modify_s(Dn,Attrs);

   Attribs = "";
   if Show == 1:
      Attrs = l.search_s(BaseDn,ldap.SCOPE_ONELEVEL,"uid="+GetAttr(DnRecord,"uid"));
      if len(Attrs) == 0:
         raise Error, "User not found"
      Attribs = GPGEncrypt(PrettyShow(Attrs[0])+"\n","0x"+Key[1],Key[4]);
      
   Subst = {};
   Subst["__FROM__"] = ChangeFrom;
   Subst["__EMAIL__"] = EmailAddress(DnRecord);
   Subst["__ADMIN__"] = ReplyTo;
   Subst["__RESULT__"] = Result;
   Subst["__ATTR__"] = Attribs;

   return Reply + TemplateSubst(Subst,open(TemplatesDir+"change-reply","r").read());
   
# Handle ping handles an email sent to the 'ping' address (ie this program
# called with a ping argument) It replies with a dump of the public records.
def HandlePing(Reply,DnRecord,Key):
   Subst = {};
   Subst["__FROM__"] = PingFrom;
   Subst["__EMAIL__"] = EmailAddress(DnRecord);
   Subst["__LDAPFIELDS__"] = PrettyShow(DnRecord);
   Subst["__ADMIN__"] = ReplyTo;

   return Reply + TemplateSubst(Subst,open(TemplatesDir+"ping-reply","r").read());

# Handle a change password email sent to the change password address
# (this program called with the chpass argument)
def HandleChPass(Reply,DnRecord,Key):
   # Generate a random password
   Password = GenPass();
   Pass = HashPass(Password);
      
   # Use GPG to encrypt it      
   Message = GPGEncrypt("Your new password is '" + Password + "'\n",\
                        "0x"+Key[1],Key[4]);
   Password = None;

   if Message == None:
      raise Error, "Unable to generate the encrypted reply, gpg failed.";

   if (Key[4] == 1):
      Type = "Your message was encrypted using PGP 2.x\ncompatibility mode.";
   else:
      Type = "Your message was encrypted using GPG (OpenPGP)\ncompatibility "\
             "mode, without IDEA. This message cannot be decoded using PGP 2.x";
   
   Subst = {};
   Subst["__FROM__"] = ChPassFrom;
   Subst["__EMAIL__"] = EmailAddress(DnRecord);
   Subst["__CRYPTTYPE__"] = Type;
   Subst["__PASSWORD__"] = Message;
   Subst["__ADMIN__"] = ReplyTo;
   Reply = Reply + TemplateSubst(Subst,open(TemplatesDir+"passwd-changed","r").read());
   
   # Connect to the ldap server
   l = ldap.open(LDAPServer);
   F = open(PassDir+"/pass-"+pwd.getpwuid(os.getuid())[0],"r");
   AccessPass = string.split(string.strip(F.readline())," ");
   F.close();
   l.simple_bind_s("uid="+AccessPass[0]+","+BaseDn,AccessPass[1]);

   # Check for a locked account
   Attrs = l.search_s(BaseDn,ldap.SCOPE_ONELEVEL,"uid="+GetAttr(DnRecord,"uid"));
   if (string.find(GetAttr(Attrs[0],"userpassword"),"*LK*")  != -1):
      raise Error, "This account is locked";

   # Modify the password
   Rec = [(ldap.MOD_REPLACE,"userPassword","{crypt}"+Pass)];
   Dn = "uid=" + GetAttr(DnRecord,"uid") + "," + BaseDn;
   l.modify_s(Dn,Rec);

   return Reply;
      
# Start of main program

# Drop messages from a mailer daemon.
if os.environ.has_key('SENDER') == 0 or len(os.environ['SENDER']) == 0:
   sys.exit(0);

ErrMsg = "Indeterminate Error";
ErrType = EX_TEMPFAIL;
try:
   # Startup the replay cache
   ErrType = EX_TEMPFAIL;
   ErrMsg = "Failed to initialize the replay cache:";
   RC = ReplayCache(ReplayCacheFile);
   RC.Clean();

   # Get the email 
   ErrType = EX_PERMFAIL;
   ErrMsg = "Failed to understand the email or find a signature:";
   Email = mimetools.Message(sys.stdin,0);
   Msg = GetClearSig(Email);

   ErrMsg = "Message is not PGP signed:"
   if string.find(Msg[0],"-----BEGIN PGP SIGNED MESSAGE-----") == -1:
      raise Error, "No PGP signature";
   
   # Check the signature
   ErrMsg = "Unable to check the signature or the signature was invalid:";
   Res = GPGCheckSig(Msg[0]);

   if Res[0] != None:
      raise Error, Res[0];
      
   if Res[3] == None:
      raise Error, "Null signature text";

   # Extract the plain message text in the event of mime encoding
   global PlainText;
   ErrMsg = "Problem stripping MIME headers from the decoded message"
   if Msg[1] == 1:
      try:
         Index = string.index(Res[3],"\n\n") + 2;
      except ValueError:
         Index = string.index(Res[3],"\n\r\n") + 3;
      PlainText = Res[3][Index:];
   else:
      PlainText = Res[3];   

   # Check the signature against the replay cache
   ErrMsg = "The replay cache rejected your message. Check your clock!";
   Rply = RC.Check(Res[1]);
   if Rply != None:
      raise Error, Rply;
   RC.Add(Res[1]);

   # Connect to the ldap server
   ErrType = EX_TEMPFAIL;
   ErrMsg = "An error occured while performing the LDAP lookup";
   global l;
   l = ldap.open(LDAPServer);
   l.simple_bind_s("","");

   # Search for the matching key fingerprint
   Attrs = l.search_s(BaseDn,ldap.SCOPE_ONELEVEL,"keyfingerprint=" + Res[2][1]);
   if len(Attrs) == 0:
      raise Error, "Key not found"
   if len(Attrs) != 1:
      raise Error, "Oddly your key fingerprint is assigned to more than one account.."

   # Determine the sender address
   ErrType = EX_PERMFAIL;
   ErrMsg = "A problem occured while trying to formulate the reply";
   Sender = Email.getheader("Reply-To");
   if Sender == None:
      Sender = Email.getheader("From");
   if Sender == None:
      raise Error, "Unable to determine the sender's address";

   if (string.find(GetAttr(Attrs[0],"userpassword"),"*LK*")  != -1):
      raise Error, "This account is locked";

   # Formulate a reply
   Date = time.strftime("%a, %d %b %Y %H:%M:%S +0000",time.gmtime(time.time()));
   Reply = "To: %s\nReply-To: %s\nDate: %s\n" % (Sender,ReplyTo,Date);

   # Dispatch
   if sys.argv[1] == "ping":
      Reply = HandlePing(Reply,Attrs[0],Res[2]);
   elif sys.argv[1] == "chpass":
      if string.find(string.strip(PlainText),"Please change my Debian password") != 0:
         raise Error,"Please send a signed message where the first line of text is the string 'Please change my Debian password'";
      Reply = HandleChPass(Reply,Attrs[0],Res[2]);
   elif sys.argv[1] == "change":
      Reply = HandleChange(Reply,Attrs[0],Res[2]);
   else:
      print sys.argv;
      raise Error, "Incorrect Invokation";

   # Send the message through sendmail      
   ErrMsg = "A problem occured while trying to send the reply";
   Child = os.popen("/usr/sbin/sendmail -t","w");
#   Child = os.popen("cat","w");
   Child.write(Reply);
   if Child.close() != None:
      raise Error, "Sendmail gave a non-zero return code";

except:
   # Error Reply Header
   Date = time.strftime("%a, %d %b %Y %H:%M:%S +0000",time.gmtime(time.time()));
   ErrReplyHead = "To: %s\nReply-To: %s\nDate: %s\n" % (os.environ['SENDER'],ReplyTo,Date);

   # Error Body
   Subst = {};
   Subst["__ERROR__"] = ErrMsg;
   Subst["__ADMIN__"] = ReplyTo;

   Trace = "==> %s: %s\n" %(sys.exc_type,sys.exc_value);
   List = traceback.extract_tb(sys.exc_traceback);
   if len(List) > 1:
      Trace = Trace + "Python Stack Trace:\n";
      for x in List:
         Trace = Trace +  "   %s %s:%u: %s\n" %(x[2],x[0],x[1],x[3]);

   Subst["__TRACE__"] = Trace;

   # Try to send the bounce
   try:
      ErrReply = TemplateSubst(Subst,open(TemplatesDir+"error-reply","r").read());

      Child = os.popen("/usr/sbin/sendmail -t","w");
      Child.write(ErrReplyHead);
      Child.write(ErrReply);
      if Child.close() != None:
         raise Error, "Sendmail gave a non-zero return code";
   except:
      sys.exit(EX_TEMPFAIL);
      
   if ErrType != EX_PERMFAIL:
      sys.exit(ErrType);
   sys.exit(0);