Merge dkimpy-milter:dkg/test-suite into dkimpy-milter:1_0

[dkg]

This series fixes several minor bugs and adds a rudimentary overall test suite, invokable via:

    tests/runtests

the test suite doesn't cover everything, but it works from the outside of dkimpy-milter itself (using opendkim's miltertest lua scripting language) and exercises basic signing and verification mechanisms.

Having the test suite in place makes it possible to do things like conversion to python3 while knowing that the major functionality at least is intact.

diff --git a/.gitignore b/.gitignore
index 9e59230..8bd7e59 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1,3 +1,4 @@
 dist
 dkimpy_milter.egg-info
 *.pyc
+*~
diff --git a/dkimpy_milter/__init__.py b/dkimpy_milter/__init__.py
index 3791748..5345fc7 100644
--- a/dkimpy_milter/__init__.py
+++ b/dkimpy_milter/__init__.py
@@ -61,7 +61,9 @@ class dkimMilter(Milter.Base):
         self.external_connection = False
         self.hello_name = None
         # sometimes people put extra space in sendmail config, so we strip
-        self.receiver = self.getsymval('j').strip()
+        self.receiver = self.getsymval('j')
+        if self.receiver is not None:
+            self.receiver = self.receiver.strip()
         try:
             self.AuthservID = milterconfig['AuthservID']
         except:
@@ -258,7 +260,12 @@ class dkimMilter(Milter.Base):
         for y in range(self.has_dkim):  # Verify _ALL_ the signatures
             d = dkim.DKIM(txt)
             try:
-                res = d.verify(idx=y)
+                dnsoverride = milterconfig.get('DNSOverride')
+                if isinstance(dnsoverride, str):
+                    syslog.syslog("DNSOverride: {0}".format(dnsoverride))
+                    res = d.verify(idx=y, dnsfunc=lambda _x: dnsoverride)
+                else:
+                    res = d.verify(idx=y)
                 if res:
                     if d.signature_fields.get(b'a') == 'ed25519-sha256':
                         self.dkim_comment = ('Good {0} signature'
diff --git a/dkimpy_milter/__main__.py b/dkimpy_milter/__main__.py
new file mode 100644
index 0000000..8c5cf9c
--- /dev/null
+++ b/dkimpy_milter/__main__.py
@@ -0,0 +1,6 @@
+#!/usr/bin/python2
+
+from dkimpy_milter import main
+
+if __name__ == "__main__":
+    main()
diff --git a/dkimpy_milter/config.py b/dkimpy_milter/config.py
index 9f42af2..d562e97 100644
--- a/dkimpy_milter/config.py
+++ b/dkimpy_milter/config.py
@@ -48,6 +48,7 @@ defaultConfigData = {
     'DiagnosticDirectory': '',
     'MacroList': '',
     'MacroListVerify': '',
+    'DNSOverride': None,
     'debugLevel': 0  # Undocumented config item for developer use
     }
 
@@ -334,6 +335,7 @@ def _readConfigFile(path, configData=None, configGlobal={}):
         'DiagnosticDirectory': 'str',
         'MacroList': 'dataset',
         'MacroListVerify': 'dataset',
+        'DNSOverride': 'str',
         'debugLevel': 'int'
         }
 
@@ -388,7 +390,10 @@ def _readConfigFile(path, configData=None, configGlobal={}):
         if conversion == 'bool':
             configData[name] = _find_boolean(value)
         elif conversion == 'str':
-            configData[name] = str(value)
+            if isinstance(value, list):
+                configData[name] = line.split(None, 1)[1]
+            else:
+                configData[name] = str(value)
         elif conversion == 'int':
             configData[name] = int(value)
         elif conversion == 'dataset':
@@ -399,7 +404,7 @@ def _readConfigFile(path, configData=None, configGlobal={}):
             configData[name] = conversion(value)
     fp.close()
     try:
-        configData['AuthservID'] = _make_authserv_id(configData['AuthservID'])
+        configData['AuthservID'] = _make_authserv_id(configData.get('AuthservID', 'HOSTNAME'))
         configData['IntHosts'] = HostsDataset(configData['InternalHosts'])
     except:
         pass
diff --git a/dkimpy_milter/util.py b/dkimpy_milter/util.py
index 5d3f69d..17857d6 100644
--- a/dkimpy_milter/util.py
+++ b/dkimpy_milter/util.py
@@ -150,10 +150,18 @@ def own_socketfile(milterconfig):
     """If socket is Unix socket, chown to UserID before dropping privileges"""
     import os
     user, group = user_group(milterconfig.get('UserID'))
-    if milterconfig.get('Socket')[:1] == '/':
-        os.chown(milterconfig.get('Socket')[1:], user, group)
-    if milterconfig.get('Socket')[:6] == "local:":
-        os.chown(milterconfig.get('Socket')[6:], user, group)
+    offset = None
+    sockname = milterconfig.get('Socket')
+    if sockname[:1] == '/':
+        offset = 0
+    elif sockname[:6] == "local:":
+        offset = 6
+    elif sockname[:5] == "unix:":
+        offset = 5
+
+    if offset is not None:
+        if os.path.exists(sockname[offset:]):
+            os.chown(sockname[offset:], user, group)
 
 
 def read_keyfile(milterconfig, keytype):
diff --git a/man/dkimpy-milter.conf.5 b/man/dkimpy-milter.conf.5
index 3dd7612..a7e5d31 100644
--- a/man/dkimpy-milter.conf.5
+++ b/man/dkimpy-milter.conf.5
@@ -311,6 +311,13 @@ be set:
 (b) KeyTable, SigningTable, no Domain, no KeyFile, no Selector;
 [fooTable options NOT IMPLEMENTED]
 
+.TP 
+.I DNSOverride (string)
+Provide a text string that a verifying milter should use instead of
+consulting the DNS on each message.  This is useful primarily for
+testing purposes in environments where it is awkward to modify the
+system DNS resolution.  It should not be used in production.
+
 .TP
 .I PeerList (dataset)
 Identifies a set of "peers" that identifies clients whose connections
diff --git a/setup.py b/setup.py
index 41a11a5..18c2ec9 100644
--- a/setup.py
+++ b/setup.py
@@ -23,10 +23,10 @@ description = "Domain Keys Identified Mail (DKIM) signing/verifying milter for P
 
 kw = {}  # Work-around for lack of 'or' requires in setuptools.
 try:
-    import DNS
-    kw['install_requires'] = ['dkimpy>=0.7', 'pymilter', 'authres>=1.1.0', 'PyNaCl', 'ipaddress', 'PyDNS']
-except ImportError:  # If PyDNS is not installed, prefer dnspython
+    import dns
     kw['install_requires'] = ['dkimpy>=0.7', 'pymilter', 'authres>=1.1.0', 'PyNaCl', 'ipaddress', 'dnspython']
+except ImportError:  # If PyDNS is not installed, prefer dnspython
+    kw['install_requires'] = ['dkimpy>=0.7', 'pymilter', 'authres>=1.1.0', 'PyNaCl', 'ipaddress', 'PyDNS']
 
 setup(
     name='dkimpy-milter',
diff --git a/tests/00_minimal.miltertest b/tests/00_minimal.miltertest
new file mode 100644
index 0000000..fbe0849
--- /dev/null
+++ b/tests/00_minimal.miltertest
@@ -0,0 +1,12 @@
+-- -*- lua -*-
+for _, keytype in ipairs({"ed25519", "rsa"}) do
+   for _, func in ipairs({"signing", "verify"}) do
+      mt.echo("testing "..keytype.." "..func)
+      conn = mt.connect("unix:"..keytype.."."..func..".sock")
+      if conn == nil then
+         error("mt.connect() failed "..keytype.." "..func)
+      end
+      mt.disconnect(conn)
+      mt.echo(keytype.." "..func.." complete")
+   end
+end
diff --git a/tests/01_connect.miltertest b/tests/01_connect.miltertest
new file mode 100755
index 0000000..2f43eff
--- /dev/null
+++ b/tests/01_connect.miltertest
@@ -0,0 +1,40 @@
+-- -*- lua -*-
+for _, keytype in ipairs({"ed25519", "rsa"}) do
+   for _, func in ipairs({"signing", "verify"}) do
+      mt.echo("testing "..keytype.." "..func)
+      conn = mt.connect("unix:"..keytype.."."..func..".sock")
+      if conn == nil then
+         error("mt.connect() failed "..keytype.." "..func)
+      end
+      if mt.conninfo(conn, "localhost", "127.0.0.1") ~= nil then
+         error("mt.conninfo() failed "..keytype.." "..func)
+      end
+      if mt.getreply(conn) ~= SMFIR_CONTINUE then
+         error("mt.conninfo() unexpected reply "..keytype.." "..func)
+      end
+
+      if mt.test_action(conn, SMFIF_ADDHDRS) then
+         print("could add headers "..keytype.." "..func)
+      else
+         error("mt.test_action() says could not add headers "..keytype.." "..func)
+      end
+
+      if mt.test_action(conn, SMFIF_CHGHDRS) then
+         print("could change headers "..keytype.." "..func)
+      else
+         error("mt.test_action() says could not change headers "..keytype.." "..func)
+      end
+
+-- -- FIXME: this part of the test fails, as apparently the
+-- -- dkimpy-milter claims the right to change the body of a message,
+-- -- even though it shouldn't.  How can we fix the negotiation?
+--      if mt.test_action(conn, SMFIF_CHGBODY) then
+--         error("mt.test_action() says could change body "..keytype.." "..func)
+--      else
+--         print("could not change body "..keytype.." "..func)
+--      end
+
+      mt.disconnect(conn)
+      mt.echo(keytype.." "..func.." test complete")
+   end
+end
diff --git a/tests/02_sign_message.miltertest b/tests/02_sign_message.miltertest
new file mode 100644
index 0000000..cb5e7ff
--- /dev/null
+++ b/tests/02_sign_message.miltertest
@@ -0,0 +1,100 @@
+-- -*- lua -*-
+
+msg = {
+   ['headers'] = {
+      ['From'] = 'Alice <[e-mail]>',
+      ['Message-Id'] = '<[e-mail]>',
+      ['To'] = 'Bob <[e-mail]>',
+      ['Date'] = 'Mon, 18 Feb 2019 08:32:50 -0500',
+      ['Subject'] = 'Signing test',
+      ['Content-Type'] = 'text/plain',
+   },
+   ['body'] = "This is a test!\r\n",
+}
+
+-- returns miltertest connection object
+function connect_and_send (sockname, headers, body)
+   conn = mt.connect(sockname)
+   if conn == nil then
+      error "mt.connect() failed"
+   end
+   if mt.conninfo(conn, "localhost", "127.0.0.1") ~= nil then
+      error "mt.conninfo() failed"
+   end
+   if mt.getreply(conn) ~= SMFIR_CONTINUE then
+      error "mt.conninfo() unexpected reply"
+   end
+
+   -- mt.macro(conn, SMFIC_MAIL, "i", "simple-message")
+   if mt.mailfrom(conn, "<[e-mail]>") ~= nil then
+      error "mt.mailfrom() failed"
+   end
+   if mt.getreply(conn) ~= SMFIR_CONTINUE then
+      error "mt.mailfrom() unexpected reply"
+   end
+   -- mt.rcptto() is called implicitly
+
+   -- send headers
+   for key,value in pairs(headers) do
+      if mt.header(conn, key, value) ~= nil then
+         error("mt.header(" .. key .. ") failed")
+      end
+      if mt.getreply(conn) ~= SMFIR_CONTINUE then
+         error("mt.header(" .. key .. ") unexpected reply")
+      end
+   end
+   -- send EOH
+   if mt.eoh(conn) ~= nil then
+      error "mt.eoh() failed"
+   end
+   if mt.getreply(conn) ~= SMFIR_CONTINUE then
+      error "mt.eoh() unexpected reply"
+   end
+
+   -- send body
+   if mt.bodystring(conn, body) ~= nil then
+      error "mt.bodystring() failed"
+   end
+   if mt.getreply(conn) ~= SMFIR_CONTINUE then
+      error "mt.bodystring() unexpected reply"
+   end
+   -- end of message; let the filter react
+   if mt.eom(conn) ~= nil then
+      error "mt.eom() failed"
+   end
+   reply = mt.getreply(conn)
+   if reply ~= SMFIR_CONTINUE then
+      error ("mt.eom() unexpected reply: " .. reply)
+   end
+   return conn
+end
+
+for _, keytype in ipairs({"ed25519", "rsa"}) do
+   mt.echo("testing "..keytype)
+   signing = connect_and_send("unix:"..keytype..".signing.sock", msg.headers, msg.body)
+   -- verify that a test header field got added
+   if not mt.eom_check(signing, MT_HDRINSERT) then
+      error "no header added by signer"
+   end
+
+   signature = mt.getheader(signing, "DKIM-Signature", 0)
+
+   mt.disconnect(signing)
+
+   mt.echo("DKIM-Signature: " .. signature)
+
+   msg.headers['DKIM-Signature'] = signature
+
+   verify = connect_and_send("unix:"..keytype..".verify.sock", msg.headers, msg.body)
+
+   if not mt.eom_check(verify, MT_HDRINSERT) then
+      error "no header added in verify"
+   end
+
+   authres = mt.getheader(verify, "Authentication-Results", 0)
+   mt.echo("Authentication-Results: "..authres)
+
+   mt.disconnect(verify)
+
+   mt.echo(keytype.." complete")
+end
diff --git a/tests/dkimpy-milter b/tests/dkimpy-milter
new file mode 100755
index 0000000..39b64d5
--- /dev/null
+++ b/tests/dkimpy-milter
@@ -0,0 +1,2 @@
+#!/bin/sh
+python2 -m dkimpy_milter "$@"
diff --git a/tests/runtests b/tests/runtests
new file mode 100755
index 0000000..7878f17
--- /dev/null
+++ b/tests/runtests
@@ -0,0 +1,84 @@
+#!/bin/bash
+
+set -e
+WORKDIR=$(mktemp -d)
+TESTDIR=$(realpath "$(dirname "$0")")
+DKIMPY_MILTER=${DKIMPY_MILTER:-"$TESTDIR/dkimpy-milter"}
+KEY_TYPES=(ed25519 rsa)
+
+cd "$WORKDIR"
+
+printf "Testing %s from directory %s\n" "$DKIMPY_MILTER" "$WORKDIR"
+
+for keytype in "${KEY_TYPES[@]}"; do
+    dknewkey --ktype "$keytype" "testkey.$keytype"
+    if [ "$keytype" = ed25519 ]; then
+        keyfile=KeyFileEd25519
+        selector=SelectorEd25519
+    else
+        keyfile=KeyFile
+        selector=Selector
+    fi
+    cat > "$keytype.signing.conf" <<EOF
+Domain example.net
+$keyfile testkey.$keytype.key
+$selector testkey
+Socket unix:$keytype.signing.sock
+PidFile $keytype.signing.pid
+Mode s
+UserID $(id --name --user):$(id --name --group)
+EOF
+
+    cat > "$keytype.verify.conf" <<EOF
+Socket unix:$keytype.verify.sock
+PidFile $keytype.verify.pid
+Mode v
+DNSOverride $(cat testkey.$keytype.dns)
+UserID $(id --name --user):$(id --name --group)
+EOF
+done
+
+cleanup() {
+    echo cleaning up jobs:
+    jobs
+    for keytype in "${KEY_TYPES[@]}"; do
+        for func in signing verify; do
+            if [ -s "$keytype.$func.pid" ] && kill -0 "$(cat "$keytype.$func.pid")"; then
+                kill "$(cat $keytype.$func.pid)"
+            fi
+        done
+    done
+    wait
+    for keytype in "${KEY_TYPES[@]}"; do
+        for func in signing verify; do
+            errdata="$keytype.$func.stderr"
+            if [ -s "$errdata" ]; then
+                printf -- "-> %s:\n" "$errdata"
+                cat "$errdata"
+                printf -- "-> end %s\n" "$errdata"
+            fi
+        done
+    done
+    rm -rf "$WORKDIR"
+}
+
+for keytype in "${KEY_TYPES[@]}"; do
+    for func in signing verify; do
+        PYTHONPATH="$(dirname "$TESTDIR")" "$DKIMPY_MILTER" "$keytype.$func.conf" 2>"$keytype.$func.stderr" &
+    done
+done
+trap cleanup EXIT
+
+# ugly ugly (how are we supposed to know that the milters are all ready?):
+sleep 2
+
+# uses miltertest from opendkim:
+for x in ${TESTS:-"$TESTDIR"/*.miltertest}; do
+    if ! [ -e "$x" ]; then
+        if [ -e "$TESTDIR/$x" ]; then
+            x="$TESTDIR/$x"
+        fi
+    fi
+    printf -- "-> running %s...\n" "$x"
+    miltertest -s "$x"
+done