M listfix_filter.py → listfix_filter.py

@@ -4,111 +4,163 @@ import sys
 import os
 import re
 
-sender = "None"
-recipient = "None"
-if (len(sys.argv) > 2):
+########################
+## Function Defs
+########################
+
+def args_ok():
+    if (len(sys.argv) > 2):
+        if (not re_email.match(sys.argv[1]) or not re_email.match(sys.argv[2])):
+            return False
+        else:
+            return True
+    else:
+        return False
+
+def get_header(lines, header):
+    rval = None
+
+    re_header = re.compile("^" + header + ": ")
+
+    header = header.rstrip()
+    if (header[-1] == ":"):
+        header = header[0:-1]
+
+    append_next = False
+    in_header = True
+    for line in lines:
+        if (in_header):
+            if (re_header_cont.match(line) and append_next):
+                rval = rval + " " + line.rstrip().lstrip()
+                continue
+
+            append_next = False
+            if (re_header.match(line)):
+                rval = line.rstrip()
+                append_next = True
+            elif (re_header_end.match(line)):
+                in_header = False
+        else:
+            break
+
+    return rval
+
+def strip_headers(lines, exclude):
+    rval = []
+
+    append_next = False
+    in_header = True
+    for line in lines:
+        if (in_header):
+            if (re_header_cont.match(line) and append_next):
+                rval.append(line)
+                continue
+
+            if (re_header_end.match(line)):
+                rval.append(line)
+                in_header = False
+                continue
+
+            append_next = False
+            for ex in exclude:
+                if (re.match("^" + ex + ": ", line)):
+                    rval.append(line)
+                    append_next = True
+                    break
+        else:
+            rval.append(line)
+
+    return rval
+
+def send_email(to_email, email_contents):
+    p = os.popen(f"/usr/sbin/sendmail -G -i {to_email}", "w")
+    for line in email_contents:
+        p.write(line)
+    p.close()
+
+
+########################
+## Main Program
+########################
+
+re_header_cont = re.compile("^\s+\S+")
+re_header_end = re.compile("^\s*$")
+re_email = re.compile("([^<>\"\s]+)@(\S+\.[^<>\"\s]+)")
+re_sender_name = re.compile("^From:\s+\"?([^<>\"]*)\"?\s*<?(\S*)@\S+\.\S+>?$")
+re_auto_reply = re.compile("^Auto-Submitted: (auto-generated|auto-replied)", re.IGNORECASE)
+
+sender = None
+recipient = None
+to_line = None
+from_line = None
+sender_name = None
+list_email = None
+list_name = None
+list_domain = None
+email = []
+email_filtered = []
+
+## Get/check args
+
+if (args_ok()):
     sender = sys.argv[1]
     recipient = sys.argv[2]
+else:
+    raise ValueError('Missing or Invalid Arguments')
 
-#print(f"Sender: {sender}")
-#print(f"Recipient: {recipient}")
-#f = open("/tmp/filter.txt", "a")
-#f.write(f"Sender: {sender}\n")
-#f.write(f"Recipient: {recipient}\n")
-#f.close()
 
-orig_to = ""
-orig_from = ""
-list_email = ""
-list_name = ""
-list_domain = ""
+## Get email content
 
-stdin= []
 for line in sys.stdin:
-    if (list_email == "" and line[0:4] == "To: "):
-        orig_to = line[4:].rstrip()
-        list_email = re.search("\S+@\S+\.\S+", orig_to).group()
-        if (list_email[-1] == ","):
-            list_email = list_email[0:-1]
-        if (list_email[0] == "\"" and list_email[-1] == "\""):
-            list_email = list_email[1:-1]
-        elif (list_email[0] == "<" and list_email[-1] == ">"):
-            list_email = list_email[1:-1]
-        list_name = re.search("^[^@]+", list_email).group()
-        list_domain = re.search("^[^@]+@(.+)$", list_email).group(1)
-    stdin.append(line)
+    email.append(line)
+if (len(email) == 0):
+    raise ValueError('Missing Piped Data')
 
-sender_name = ""
-for line in stdin:
-    if (sender_name == "" and line[0:6] == "From: "):
-        orig_from = line[6:].rstrip()
-        if (re.search("^\"[^\"]+\"", orig_from)):
-            sender_name = re.search("^\"([^\"]+)\"", orig_from).group(1)
-        elif (re.search("^[^<]+ <", orig_from)):
-            sender_name = re.search("^([^<]+) <", orig_from).group(1)
-        else:
-            sender_name = re.search("(\S+)@\S+\.\S+", orig_from).group(1)
-            if (sender_name[0] == "\"" or sender_name[0] == "<"):
-                sender_name = sender_name[1:]
+## Check if this is an auto-reply
 
-for line in stdin:
-    if (re.search("^Auto-Submitted: auto-generated", line, re.IGNORECASE)):
-        exit()
-    if (re.search("^Auto-Submitted: auto-replied", line, re.IGNORECASE)):
-        exit()
-    if (re.search("^\s*$", line)):
-        break
+auto_sub_line = get_header(email, "Auto-Submitted")
+if (auto_sub_line and re_auto_reply.match(auto_sub_line)):
+    exit()
+
+## Get To: and From: lines
+
+to_line = get_header(email, "To")
+from_line = get_header(email, "From")
+if (not to_line or not from_line):
+    raise ValueError('Can not find To or From value in headers.')
 
-## We add the filter skip header after the from line had been changed
-## and reinjected. This is necessary to get the dkim milter to run
-## for the new "From" header. Otherwise it doesn't run.
-contents = []
-if (re.search(list_email, orig_from)):
-    contents.append(f"List-Skip-Filter: yes\n")
-    for line in stdin:
-        contents.append(line)
+## Get list info
+
+if (re_email.search(to_line)):
+    results = re_email.search(to_line)
+    list_email = results.group(0)
+    list_name = results.group(1)
+    list_domain = results.group(2)
+else:
+    raise ValueError('Can not determine email list.')
+
+## Get Sender Name
+
+if (re_sender_name.match(from_line)):
+    results = re_sender_name.search(from_line)
+    sender_name = results.group(1) if results.group(1) else results.group(2)
 else:
-    contents.append(f"To: {list_email}\n")
-    contents.append(f"From: \"{sender_name} via {list_name}\" <{list_email}>\n")
-    contents.append(f"Reply-To: {list_email}, {sender}\n")
+    raise ValueError('Can Not Determine Sender Name')
 
-    in_header = 1
-    included = 0
-    for line in stdin:
-        if (in_header == 1):
-            if (re.search("^\s+\S+", line) and included == 1):
-                contents.append(line)
-                continue
+## If this is already filtered, add skip header and resubmit
+
+if (re.search(list_email, from_line)):
+    email.insert(0, "List-Skip-Filter: yes\n")
+    send_email(list_email, email)
+    exit()
 
-            included = 0
-            if (re.search("^Subject: ", line)):
-                contents.append(line)
-                included = 1
-            elif (re.search("^Content-", line)):
-                contents.append(line)
-                included = 1
-            elif (re.search("^\s*$", line)):
-                contents.append(line)
-                in_header = 0
-        else:
-            contents.append(line)
+## Costruct Filtered Email
 
-    #found_from = 0
-    #found_to = 0
-    #for line in stdin:
-    #    if (found_from == 0 and line[0:6] == "From: "):
-    #        line = f"From: \"{sender_name} via {list_name}\" <{list_email}>\n"
-    #        contents.append(f"Reply-To: {sender}, {list_email}\n")
-    #        found_from = 1
-    #    elif (found_to == 0 and line[0:4] == "To: "):
-    #        line = f"To: {list_email}\n"
-    #        found_to = 1
-    #    contents.append(line)
+email_filtered.append(f"To: {list_email}\n")
+email_filtered.append(f"From: \"{sender_name} via {list_name}\" <{list_email}>\n")
+email_filtered.append(f"Reply-To: {list_email}, {sender}\n")
 
-#for line in contents:
-#    print(line, end = "")
+exclude_headers = ["Subject", "Content-[^:]+", "MIME-Version"]
+email_filtered.extend(strip_headers(email, exclude_headers))
 
-p = os.popen(f"/usr/sbin/sendmail -G -i {list_email}", "w")
-for line in contents:
-    p.write(line)
-p.close()
+send_email(list_email, email_filtered)