X-Git-Url: http://dolda2000.com/gitweb/?a=blobdiff_plain;f=acmecert;h=14d0f004fb9ba7a524a186b6b4271aa7c48ebf97;hb=HEAD;hp=6136eaa39bd7d51875ba6c3f42499769feec4510;hpb=bfe6116d27b1e8d48abcd91f3a503306d7b75812;p=utils.git

diff --git a/acmecert b/acmecert
index 6136eaa..14d0f00 100755
--- a/acmecert
+++ b/acmecert
@@ -1,17 +1,15 @@
 #!/usr/bin/python3
 
-import sys, os, getopt, binascii, json, pprint, signal, time
+#### ACME client (only http-01 challenges supported thus far)
+
+import sys, os, getopt, binascii, json, pprint, signal, time, calendar, threading
 import urllib.request
-import Crypto.PublicKey.RSA, Crypto.Random, Crypto.Hash.SHA256, Crypto.Signature.PKCS1_v1_5
 
-service = "https://acme-v02.api.letsencrypt.org/directory"
-_directory = None
-def directory():
-    global _directory
-    if _directory is None:
-        with req(service) as resp:
-            _directory = json.loads(resp.read().decode("utf-8"))
-    return _directory
+### General utilities
+
+class msgerror(Exception):
+    def report(self, out):
+        out.write("acmecert: undefined error\n")
 
 def base64url(dat):
     return binascii.b2a_base64(dat).decode("us-ascii").translate({43: 45, 47: 95, 61: None}).strip()
@@ -21,49 +19,234 @@ def ebignum(num):
     if len(h) % 2 == 1: h = "0" + h
     return base64url(binascii.a2b_hex(h))
 
-def getnonce():
-    with urllib.request.urlopen(directory()["newNonce"]) as resp:
-        resp.read()
-        return resp.headers["Replay-Nonce"]
+class maybeopen(object):
+    def __init__(self, name, mode):
+        if name == "-":
+            self.opened = False
+            if mode == "r":
+                self.fp = sys.stdin
+            elif mode == "w":
+                self.fp = sys.stdout
+            else:
+                raise ValueError(mode)
+        else:
+            self.opened = True
+            self.fp = open(name, mode)
 
-def req(url, data=None, ctype=None, headers={}, method=None, **kws):
-    if data is not None and not isinstance(data, bytes):
-        data = json.dumps(data).encode("utf-8")
-        ctype = "application/jose+json"
-    req = urllib.request.Request(url, data=data, method=method)
-    for hnam, hval in headers.items():
-        req.add_header(hnam, hval)
-    if ctype is not None:
-        req.add_header("Content-Type", ctype)
-    return urllib.request.urlopen(req)
+    def __enter__(self):
+        return self.fp
 
-def jreq(url, data, auth):
-    authdata = {"alg": "RS256", "url": url, "nonce": getnonce()}
-    authdata.update(auth.authdata())
-    authdata = base64url(json.dumps(authdata).encode("us-ascii"))
-    if data is None:
-        data = ""
-    else:
-        data = base64url(json.dumps(data).encode("us-ascii"))
-    seal = base64url(auth.sign(("%s.%s" % (authdata, data)).encode("us-ascii")))
-    enc = {"protected": authdata, "payload": data, "signature": seal}
-    with req(url, data=enc) as resp:
-        return json.loads(resp.read().decode("utf-8")), resp.headers
+    def __exit__(self, *excinfo):
+        if self.opened:
+            self.fp.close()
+        return False
+
+### Crypto utilities
+
+_cryptobke = None
+def cryptobke():
+    global _cryptobke
+    if _cryptobke is None:
+        from cryptography.hazmat import backends
+        _cryptobke = backends.default_backend()
+    return _cryptobke
+
+class dererror(Exception):
+    pass
+
+class pemerror(Exception):
+    pass
+
+def pemdec(pem, ptypes):
+    if isinstance(ptypes, str):
+        ptypes = [ptypes]
+    p = 0
+    while True:
+        p = pem.find("-----BEGIN ", p)
+        if p < 0:
+            raise pemerror("could not find any %s in PEM-encoded data" % (ptypes,))
+        p2 = pem.find("-----", p + 11)
+        if p2 < 0:
+            raise pemerror("incomplete PEM header")
+        ptype = pem[p + 11 : p2]
+        if ptype not in ptypes:
+            p = p2 + 5
+            continue
+        p3 = pem.find("-----END " + ptype + "-----", p2 + 5)
+        if p3 < 0:
+            raise pemerror("incomplete PEM data")
+        pem = pem[p2 + 5 : p3]
+        return binascii.a2b_base64(pem)
+
+class derdecoder(object):
+    def __init__(self, data, offset=0, size=None):
+        self.data = data
+        self.offset = offset
+        self.size = len(data) if size is None else size
+
+    def end(self):
+        return self.offset >= self.size
+
+    def byte(self):
+        if self.offset >= self.size:
+            raise dererror("unexpected end-of-data")
+        ret = self.data[self.offset]
+        self.offset += 1
+        return ret
+
+    def splice(self, ln):
+        if self.offset + ln > self.size:
+            raise dererror("unexpected end-of-data")
+        ret = self.data[self.offset : self.offset + ln]
+        self.offset += ln
+        return ret
+
+    def dectag(self):
+        h = self.byte()
+        cl = (h & 0xc0) >> 6
+        cons = (h & 0x20) != 0
+        tag = h & 0x1f
+        if tag == 0x1f:
+            raise dererror("extended type tags not supported")
+        return cl, cons, tag
+
+    def declen(self):
+        h = self.byte()
+        if (h & 0x80) == 0:
+            return h
+        if h == 0x80:
+            raise dererror("indefinite lengths not supported in DER")
+        if h == 0xff:
+            raise dererror("invalid length byte")
+        n = h & 0x7f
+        ret = 0
+        for i in range(n):
+            ret = (ret << 8) + self.byte()
+        return ret
+
+    def get(self):
+        cl, cons, tag = self.dectag()
+        ln = self.declen()
+        return cons, cl, tag, self.splice(ln)
+
+    def getcons(self, ckcl, cktag):
+        cons, cl, tag, data = self.get()
+        if not cons:
+            raise dererror("expected constructed value")
+        if (ckcl != None and ckcl != cl) or (cktag != None and cktag != tag):
+            raise dererror("unexpected value tag: got (%d, %d), expected (%d, %d)" % (cl, tag, ckcl, cktag))
+        return derdecoder(data)
+
+    def getint(self):
+        cons, cl, tag, data = self.get()
+        if (cons, cl, tag) == (False, 0, 2):
+            ret = 0
+            for b in data:
+                ret = (ret << 8) + b
+            return ret
+        raise dererror("unexpected integer type: (%s, %d, %d)" % (cons, cl, tag))
+
+    def getstr(self):
+        cons, cl, tag, data = self.get()
+        if (cons, cl, tag) == (False, 0, 12):
+            return data.decode("utf-8")
+        if (cons, cl, tag) == (False, 0, 13):
+            return data.decode("us-ascii")
+        if (cons, cl, tag) == (False, 0, 22):
+            return data.decode("us-ascii")
+        if (cons, cl, tag) == (False, 0, 30):
+            return data.decode("utf-16-be")
+        raise dererror("unexpected string type: (%s, %d, %d)" % (cons, cl, tag))
+
+    def getbytes(self):
+        cons, cl, tag, data = self.get()
+        if (cons, cl, tag) == (False, 0, 4):
+            return data
+        raise dererror("unexpected byte-string type: (%s, %d, %d)" % (cons, cl, tag))
+
+    def getoid(self):
+        cons, cl, tag, data = self.get()
+        if (cons, cl, tag) == (False, 0, 6):
+            ret = []
+            ret.append(data[0] // 40)
+            ret.append(data[0] % 40)
+            p = 1
+            while p < len(data):
+                n = 0
+                v = data[p]
+                p += 1
+                while v & 0x80:
+                    n = (n + (v & 0x7f)) * 128
+                    v = data[p]
+                    p += 1
+                n += v
+                ret.append(n)
+            return tuple(ret)
+        raise dererror("unexpected object-id type: (%s, %d, %d)" % (cons, cl, tag))
+
+    @staticmethod
+    def parsetime(data, c):
+        if c:
+            y = int(data[0:4])
+            data = data[4:]
+        else:
+            y = int(data[0:2])
+            y += 1900 if y > 50 else 2000
+            data = data[2:]
+        m = int(data[0:2])
+        d = int(data[2:4])
+        H = int(data[4:6])
+        data = data[6:]
+        if data[:1].isdigit():
+            M = int(data[0:2])
+            data = data[2:]
+        else:
+            M = 0
+        if data[:1].isdigit():
+            S = int(data[0:2])
+            data = data[2:]
+        else:
+            S = 0
+        if data[:1] == '.':
+            p = 1
+            while len(data) < p and data[p].isdigit():
+                p += 1
+            S += float("0." + data[1:p])
+            data = data[p:]
+        if len(data) < 1:
+            raise dererror("unspecified local time not supported for decoding")
+        if data[0] == 'Z':
+            tz = 0
+        elif data[0] == '+':
+            tz = (int(data[1:3]) * 60) + int(data[3:5])
+        elif data[0] == '-':
+            tz = -((int(data[1:3]) * 60) + int(data[3:5]))
+        else:
+            raise dererror("cannot parse X.690 timestamp")
+        return calendar.timegm((y, m, d, H, M, S)) - (tz * 60)
+
+    def gettime(self):
+        cons, cl, tag, data = self.get()
+        if (cons, cl, tag) == (False, 0, 23):
+            return self.parsetime(data.decode("us-ascii"), False)
+        if (cons, cl, tag) == (False, 0, 24):
+            return self.parsetime(data.decode("us-ascii"), True)
+        raise dererror("unexpected time type: (%s, %d, %d)" % (cons, cl, tag))
+
+    @classmethod
+    def frompem(cls, pem, ptypes):
+        return cls(pemdec(pem, ptypes))
 
 class certificate(object):
-    @property
-    def enddate(self):
-        # No X509 parser for Python?
-        import subprocess, re, calendar
-        with subprocess.Popen(["openssl", "x509", "-noout", "-enddate"], stdin=subprocess.PIPE, stdout=subprocess.PIPE) as openssl:
-            openssl.stdin.write(self.data.encode("us-ascii"))
-            openssl.stdin.close()
-            resp = openssl.stdout.read().decode("utf-8")
-            if openssl.wait() != 0:
-                raise Exception("openssl error")
-        m = re.search(r"notAfter=(.*)$", resp)
-        if m is None: raise Exception("unexpected openssl reply: %r" % (resp,))
-        return calendar.timegm(time.strptime(m.group(1), "%b %d %H:%M:%S %Y GMT"))
+    def __init__(self, der):
+        ci = der.getcons(0, 16).getcons(0, 16)
+        self.ver = ci.getcons(2, 0).getint()
+        self.serial = ci.getint()
+        ci.getcons(0, 16)       # Signature algorithm
+        ci.getcons(0, 16)       # Issuer
+        vl = ci.getcons(0, 16)
+        self.startdate = vl.gettime()
+        self.enddate = vl.gettime()
 
     def expiring(self, timespec):
         if timespec.endswith("y"):
@@ -82,58 +265,137 @@ class certificate(object):
 
     @classmethod
     def read(cls, fp):
-        self = cls()
-        self.data = fp.read()
-        return self
+        return cls(derdecoder.frompem(fp.read(), {"CERTIFICATE", "X509 CERTIFICATE"}))
 
 class signreq(object):
+    def __init__(self, der):
+        self.raw = der
+        req = derdecoder(der).getcons(0, 16).getcons(0, 16)
+        self.ver = req.getint()
+        req.getcons(0, 16)      # Subject
+        req.getcons(0, 16)      # Public key
+        self.altnames = []
+        if not req.end():
+            attrs = req.getcons(2, 0)
+            while not attrs.end():
+                attr = attrs.getcons(0, 16)
+                anm = attr.getoid()
+                if anm == (1, 2, 840, 113549, 1, 9, 14):
+                    # Certificate extension request
+                    exts = attr.getcons(0, 17).getcons(0, 16)
+                    while not exts.end():
+                        ext = exts.getcons(0, 16)
+                        extnm = ext.getoid()
+                        if extnm == (2, 5, 29, 17):
+                            # Subject alternative names
+                            names = derdecoder(ext.getbytes()).getcons(0, 16)
+                            while not names.end():
+                                cons, cl, tag, data = names.get()
+                                if (cons, cl, tag) == (False, 2, 2):
+                                    self.altnames.append(("DNS", data.decode("us-ascii")))
+
     def domains(self):
-        # No PCKS10 parser for Python?
-        import subprocess, re
-        with subprocess.Popen(["openssl", "req", "-noout", "-text"], stdin=subprocess.PIPE, stdout=subprocess.PIPE) as openssl:
-            openssl.stdin.write(self.data.encode("us-ascii"))
-            openssl.stdin.close()
-            resp = openssl.stdout.read().decode("utf-8")
-            if openssl.wait() != 0:
-                raise Exception("openssl error")
-        m = re.search(r"X509v3 Subject Alternative Name:[^\n]*\n\s*((\w+:\S+,\s*)*\w+:\S+)\s*\n", resp)
-        if m is None:
-            return []
-        ret = []
-        for nm in m.group(1).split(","):
-            nm = nm.strip()
-            typ, nm = nm.split(":", 1)
-            if typ == "DNS":
-                ret.append(nm)
-        return ret
+        return [nm[1] for nm in self.altnames if nm[0] == "DNS"]
 
     def der(self):
-        import subprocess
-        with subprocess.Popen(["openssl", "req", "-outform", "der"], stdin=subprocess.PIPE, stdout=subprocess.PIPE) as openssl:
-            openssl.stdin.write(self.data.encode("us-ascii"))
-            openssl.stdin.close()
-            resp = openssl.stdout.read()
-            if openssl.wait() != 0:
-                raise Exception("openssl error")
-        return resp
+        return self.raw
 
     @classmethod
     def read(cls, fp):
-        self = cls()
-        self.data = fp.read()
+        return cls(pemdec(fp.read(), {"CERTIFICATE REQUEST"}))
+
+### Somewhat general request utilities
+
+def getnonce():
+    with urllib.request.urlopen(directory()["newNonce"]) as resp:
+        resp.read()
+        return resp.headers["Replay-Nonce"]
+
+def req(url, data=None, ctype=None, headers={}, method=None, **kws):
+    if data is not None and not isinstance(data, bytes):
+        data = json.dumps(data).encode("utf-8")
+        ctype = "application/jose+json"
+    req = urllib.request.Request(url, data=data, method=method)
+    for hnam, hval in headers.items():
+        req.add_header(hnam, hval)
+    if ctype is not None:
+        req.add_header("Content-Type", ctype)
+    return urllib.request.urlopen(req)
+
+class problem(msgerror):
+    def __init__(self, code, data, *args, url=None, **kw):
+        super().__init__(*args, **kw)
+        self.code = code
+        self.data = data
+        self.url = url
+        if not isinstance(data, dict):
+            raise ValueError("unexpected problem object type: %r" % (data,))
+
+    @property
+    def type(self):
+        return self.data.get("type", "about:blank")
+    @property
+    def title(self):
+        return self.data.get("title")
+    @property
+    def detail(self):
+        return self.data.get("detail")
+
+    def report(self, out):
+        extra = None
+        if self.title is None:
+            msg = self.detail
+            if "\n" in msg:
+                extra, msg = msg, None
+        else:
+            msg = self.title
+            extra = self.detail
+        if msg is None:
+            msg = self.data.get("type")
+        if msg is not None:
+            out.write("acemcert: %s: %s\n" % (
+                ("remote service error" if self.url is None else self.url),
+                ("unspecified error" if msg is None else msg)))
+        if extra is not None:
+            out.write("%s\n" % (extra,))
+
+    @classmethod
+    def read(cls, err, **kw):
+        self = cls(err.code, json.loads(err.read().decode("utf-8")), **kw)
         return self
 
+def jreq(url, data, auth):
+    authdata = {"alg": "RS256", "url": url, "nonce": getnonce()}
+    authdata.update(auth.authdata())
+    authdata = base64url(json.dumps(authdata).encode("us-ascii"))
+    if data is None:
+        data = ""
+    else:
+        data = base64url(json.dumps(data).encode("us-ascii"))
+    seal = base64url(auth.sign(("%s.%s" % (authdata, data)).encode("us-ascii")))
+    enc = {"protected": authdata, "payload": data, "signature": seal}
+    try:
+        with req(url, data=enc) as resp:
+            return json.loads(resp.read().decode("utf-8")), resp.headers
+    except urllib.error.HTTPError as exc:
+        if exc.headers["Content-Type"] == "application/problem+json":
+            raise problem.read(exc, url=url)
+        raise
+
+## Authentication
+
 class jwkauth(object):
     def __init__(self, key):
         self.key = key
 
     def authdata(self):
-        return {"jwk": {"kty": "RSA", "e": ebignum(self.key.e), "n": ebignum(self.key.n)}}
+        pub = self.key.public_key().public_numbers()
+        return {"jwk": {"kty": "RSA", "e": ebignum(pub.e), "n": ebignum(pub.n)}}
 
     def sign(self, data):
-        dig = Crypto.Hash.SHA256.new()
-        dig.update(data)
-        return Crypto.Signature.PKCS1_v1_5.new(self.key).sign(dig)
+        from cryptography.hazmat.primitives import hashes
+        from cryptography.hazmat.primitives.asymmetric import padding
+        return self.key.sign(data, padding.PKCS1v15(), hashes.SHA256())
 
 class account(object):
     def __init__(self, uri, key):
@@ -144,9 +406,9 @@ class account(object):
         return {"kid": self.uri}
 
     def sign(self, data):
-        dig = Crypto.Hash.SHA256.new()
-        dig.update(data)
-        return Crypto.Signature.PKCS1_v1_5.new(self.key).sign(dig)
+        from cryptography.hazmat.primitives import hashes
+        from cryptography.hazmat.primitives.asymmetric import padding
+        return self.key.sign(data, padding.PKCS1v15(), hashes.SHA256())
 
     def getinfo(self):
         data, headers = jreq(self.uri, None, self)
@@ -158,18 +420,79 @@ class account(object):
             raise Exception("account is not valid: %s" % (data.get("status", "\"\"")))
 
     def write(self, out):
+        from cryptography.hazmat.primitives import serialization
         out.write("%s\n" % (self.uri,))
-        out.write("%s\n" % (self.key.exportKey().decode("us-ascii"),))
+        out.write("%s\n" % (self.key.private_bytes(
+            encoding=serialization.Encoding.PEM,
+            format=serialization.PrivateFormat.TraditionalOpenSSL,
+            encryption_algorithm=serialization.NoEncryption()
+        ).decode("us-ascii"),))
 
     @classmethod
     def read(cls, fp):
+        from cryptography.hazmat.primitives import serialization
         uri = fp.readline()
         if uri == "":
             raise Exception("missing account URI")
         uri = uri.strip()
-        key = Crypto.PublicKey.RSA.importKey(fp.read())
+        key = serialization.load_pem_private_key(fp.read().encode("us-ascii"), password=None, backend=cryptobke())
         return cls(uri, key)
 
+### ACME protocol
+
+service = "https://acme-v02.api.letsencrypt.org/directory"
+_directory = None
+def directory():
+    global _directory
+    if _directory is None:
+        with req(service) as resp:
+            _directory = json.loads(resp.read().decode("utf-8"))
+    return _directory
+
+def register(keysize=4096):
+    from cryptography.hazmat.primitives.asymmetric import rsa
+    key = rsa.generate_private_key(public_exponent=65537, key_size=keysize, backend=cryptobke())
+    data, headers = jreq(directory()["newAccount"], {"termsOfServiceAgreed": True}, jwkauth(key))
+    return account(headers["Location"], key)
+    
+def mkorder(acct, csr):
+    data, headers = jreq(directory()["newOrder"], {"identifiers": [{"type": "dns", "value": dn} for dn in csr.domains()]}, acct)
+    data["acmecert.location"] = headers["Location"]
+    return data
+
+def httptoken(acct, ch):
+    from cryptography.hazmat.primitives import hashes
+    pub = acct.key.public_key().public_numbers()
+    jwk = {"kty": "RSA", "e": ebignum(pub.e), "n": ebignum(pub.n)}
+    dig = hashes.Hash(hashes.SHA256(), backend=cryptobke())
+    dig.update(json.dumps(jwk, separators=(',', ':'), sort_keys=True).encode("us-ascii"))
+    khash = base64url(dig.finalize())
+    return ch["token"], ("%s.%s" % (ch["token"], khash))
+
+def finalize(acct, csr, orderid):
+    order, headers = jreq(orderid, None, acct)
+    if order["status"] == "valid":
+        pass
+    elif order["status"] == "ready":
+        jreq(order["finalize"], {"csr": base64url(csr.der())}, acct)
+        for n in range(30):
+            resp, headers = jreq(orderid, None, acct)
+            if resp["status"] == "processing":
+                time.sleep(2)
+            elif resp["status"] == "valid":
+                order = resp
+                break
+            else:
+                raise Exception("unexpected order status when finalizing: %s" % resp["status"])
+        else:
+            raise Exception("order finalization timed out")
+    else:
+        raise Exception("unexpected order state when finalizing: %s" % (order["status"],))
+    with req(order["certificate"]) as resp:
+        return resp.read().decode("us-ascii")
+
+## http-01 challenge
+
 class htconfig(object):
     def __init__(self):
         self.roots = {}
@@ -187,25 +510,6 @@ class htconfig(object):
                 sys.stderr.write("acmecert: warning: unknown htconfig directive: %s\n" % (words[0]))
         return self
 
-def register(keysize=4096):
-    key = Crypto.PublicKey.RSA.generate(keysize, Crypto.Random.new().read)
-    # jwk = {"kty": "RSA", "e": ebignum(key.e), "n": ebignum(key.n)}
-    # cjwk = json.dumps(jwk, separators=(',', ':'), sort_keys=True)
-    data, headers = jreq(directory()["newAccount"], {"termsOfServiceAgreed": True}, jwkauth(key))
-    return account(headers["Location"], key)
-    
-def mkorder(acct, csr):
-    data, headers = jreq(directory()["newOrder"], {"identifiers": [{"type": "dns", "value": dn} for dn in csr.domains()]}, acct)
-    data["acmecert.location"] = headers["Location"]
-    return data
-
-def httptoken(acct, ch):
-    jwk = {"kty": "RSA", "e": ebignum(acct.key.e), "n": ebignum(acct.key.n)}
-    dig = Crypto.Hash.SHA256.new()
-    dig.update(json.dumps(jwk, separators=(',', ':'), sort_keys=True).encode("us-ascii"))
-    khash = base64url(dig.digest())
-    return ch["token"], ("%s.%s" % (ch["token"], khash))
-
 def authorder(acct, htconf, orderid):
     order, headers = jreq(orderid, None, acct)
     valid = False
@@ -248,6 +552,13 @@ def authorder(acct, htconf, orderid):
                     resp, headers = jreq(ch["url"], {}, acct)
                     if resp["status"] == "processing":
                         time.sleep(2)
+                    elif resp["status"] == "pending":
+                        # I don't think this should happen, but it
+                        # does. LE bug? Anyway, just retry.
+                        if n < 5:
+                            time.sleep(2)
+                        else:
+                            break
                     elif resp["status"] == "valid":
                         break
                     else:
@@ -257,54 +568,19 @@ def authorder(acct, htconf, orderid):
             finally:
                 os.unlink(tokpath)
 
-def finalize(acct, csr, orderid):
-    order, headers = jreq(orderid, None, acct)
-    if order["status"] == "valid":
-        pass
-    elif order["status"] == "ready":
-        jreq(order["finalize"], {"csr": base64url(csr.der())}, acct)
-        for n in range(30):
-            resp, headers = jreq(orderid, None, acct)
-            if resp["status"] == "processing":
-                time.sleep(2)
-            elif resp["status"] == "valid":
-                order = resp
-                break
-            else:
-                raise Exception("unexpected order status when finalizing: %s" % resp["status"])
-        else:
-            raise Exception("order finalization timed out")
-    else:
-        raise Exception("unexpected order state when finalizing: %s" % (order["status"],))
-    with req(order["certificate"]) as resp:
-        return resp.read().decode("us-ascii")
-
-class maybeopen(object):
-    def __init__(self, name, mode):
-        if name == "-":
-            self.opened = False
-            if mode == "r":
-                self.fp = sys.stdin
-            elif mode == "w":
-                self.fp = sys.stdout
-            else:
-                raise ValueError(mode)
-        else:
-            self.opened = True
-            self.fp = open(name, mode)
+### Invocation and commands
 
-    def __enter__(self):
-        return self.fp
+invdata = threading.local()
+commands = {}
 
-    def __exit__(self, *excinfo):
-        if self.opened:
-            self.fp.close()
-        return False
+class usageerr(msgerror):
+    def __init__(self):
+        self.cmd = invdata.cmd
 
-class usageerr(Exception):
-    pass
+    def report(self, out):
+        out.write("%s\n" % (self.cmd.__doc__,))
 
-commands = {}
+## User commands
 
 def cmd_reg(args):
     "usage: acmecert reg [OUTPUT-FILE]"
@@ -318,7 +594,7 @@ def cmd_validate_acct(args):
     "usage: acmecert validate-acct ACCOUNT-FILE"
     if len(args) < 2: raise usageerr()
     with maybeopen(args[1], "r") as fp:
-        account.read(fp).valudate()
+        account.read(fp).validate()
 commands["validate-acct"] = cmd_validate_acct
 
 def cmd_acct_info(args):
@@ -326,11 +602,11 @@ def cmd_acct_info(args):
     if len(args) < 2: raise usageerr()
     with maybeopen(args[1], "r") as fp:
         pprint.pprint(account.read(fp).getinfo())
-commands["acct-info"] = cmd_validate_acct
+commands["acct-info"] = cmd_acct_info
 
 def cmd_order(args):
     "usage: acmecert order ACCOUNT-FILE CSR [OUTPUT-FILE]"
-    if len(args) < 4: raise usageerr()
+    if len(args) < 3: raise usageerr()
     with maybeopen(args[1], "r") as fp:
         acct = account.read(fp)
     with maybeopen(args[2], "r") as fp:
@@ -398,6 +674,8 @@ def cmd_directory(args):
     pprint.pprint(directory())
 commands["directory"] = cmd_directory
 
+## Main invocation
+
 def usage(out):
     out.write("usage: acmecert [-D SERVICE] COMMAND [ARGS...]\n")
     out.write("       acmecert -h [COMMAND]\n")
@@ -440,9 +718,13 @@ def main(argv):
         usage(sys.stderr)
         sys.exit(1)
     try:
-        cmd(args)
-    except usageerr:
-        sys.stderr.write("%s\n" % (cmd.__doc__,))
+        try:
+            invdata.cmd = cmd
+            cmd(args)
+        finally:
+            invdata.cmd = None
+    except msgerror as exc:
+        exc.report(sys.stderr)
         sys.exit(1)
 
 if __name__ == "__main__":