baseconv: add 'desc' attr, make error msgs more user-friendly

mmgen/util.py

@@ -281,8 +281,15 @@ def is_utf8(s): return is_ascii(s,enc='utf8')
 
 class baseconv(object):
 
-	mn_base = 1626 # tirosh list is 1633 words long!
-	mn_ids = ('mmgen','tirosh')
+	desc = {
+		'b58':   ('base58',               'base58-encoded data'),
+		'b32':   ('MMGen base32',         'MMGen base32-encoded data created using simple base conversion'),
+		'b16':   ('hexadecimal string',   'base16 (hexadecimal) string data'),
+		'b10':   ('base10 string',        'base10 (decimal) string data'),
+		'b8':    ('base8 string',         'base8 (octal) string data'),
+		'mmgen': ('MMGen native mnemonic',
+		'MMGen native mnemonic seed phrase data created using old Electrum wordlist and simple base conversion'),
+	}
 	digits = {
 		'b58': tuple('123456789ABCDEFGHJKLMNPQRSTUVWXYZabcdefghijkmnopqrstuvwxyz'),
 		'b32': tuple('ABCDEFGHIJKLMNOPQRSTUVWXYZ234567'),
@@ -290,6 +297,8 @@ class baseconv(object):
 		'b10': tuple('0123456789'),
 		'b8':  tuple('01234567'),
 	}
+	mn_base = 1626 # tirosh list is 1633 words long!
+	mn_ids = ('mmgen','tirosh')
 	wl_chksums = {
 		'mmgen':  '5ca31424',
 		'tirosh': '48f05e1f', # tirosh truncated to mn_base (1626)
@@ -371,16 +380,17 @@ class baseconv(object):
 		"convert string or list data of base 'wl_id' to byte string"
 
 		words = words_arg if isinstance(words_arg,(list,tuple)) else tuple(words_arg.strip())
+		desc = cls.desc[wl_id][0]
 
 		if len(words) == 0:
-			raise BaseConversionError('empty {} data'.format(wl_id))
+			raise BaseConversionError('empty {} data'.format(desc))
 
 		def get_seed_pad():
 			assert wl_id in cls.seed_pad_lens_rev,'seed padding not supported for base {!r}'.format(wl_id)
 			d = cls.seed_pad_lens_rev[wl_id]
 			if not len(words) in d:
 				m = '{}: invalid length for seed-padded {} data in base conversion'
-				raise BaseConversionError(m.format(len(words),wl_id))
+				raise BaseConversionError(m.format(len(words),desc))
 			return d[len(words)]
 
 		pad_val = max(cls.get_pad(pad,get_seed_pad),1)
@@ -388,8 +398,8 @@ class baseconv(object):
 		base = len(wl)
 
 		if not set(words) <= set(wl):
-			m = ('{w!r}:','seed data')[pad=='seed'] + ' not in {i} (base{b}) format'
-			raise BaseConversionError(m.format(w=words_arg,i=wl_id,b=base))
+			m = ('{w!r}:','seed data')[pad=='seed'] + ' not in {d} format'
+			raise BaseConversionError(m.format(w=words_arg,d=desc))
 
 		ret = sum([wl.index(words[::-1][i])*(base**i) for i in range(len(words))])
 		bl = ret.bit_length()
@@ -416,7 +426,7 @@ class baseconv(object):
 			assert wl_id in cls.seed_pad_lens,'seed padding not supported for base {!r}'.format(wl_id)
 			d = cls.seed_pad_lens[wl_id]
 			if not len(bytestr) in d:
-				m = '{}: invalid seed byte length for seed-padded base conversion'
+				m = '{}: invalid byte length for seed data in seed-padded base conversion'
 				raise SeedLengthError(m.format(len(bytestr)))
 			return d[len(bytestr)]
 

test/unit_tests_d/ut_baseconv.py

@@ -157,16 +157,16 @@ class unit_test(object):
 ('hexstr',          'HexadecimalStringError', ': not a hexadecimal str', lambda:fh('x','b58')),
 ('hexstr (seed)',   'HexadecimalStringError', 'seed data not a hexadec', lambda:fh('x','b58',pad='seed')),
 ('hexstr (empty)',  'BaseConversionError',    'empty data not allowed',  lambda:fh('','b58')),
-('b58 data',        'BaseConversionError',    ': not in b58',            lambda:th('IfFzZ','b58')),
-('b58 data (seed)', 'BaseConversionError',    'seed data not in b58',    lambda:th(bad_b58,'b58',pad='seed')),
+('b58 data',        'BaseConversionError',    ': not in base58',         lambda:th('IfFzZ','b58')),
+('b58 data (seed)', 'BaseConversionError',    'seed data not in base58', lambda:th(bad_b58,'b58',pad='seed')),
 ('b58 len (seed)',  'BaseConversionError',    'invalid length for',      lambda:th(bad_b58len,'b58',pad='seed')),
-('b58 data (empty)','BaseConversionError',    'empty b58 data',          lambda:th('','b58')),
-('b8 data (empty)' ,'BaseConversionError',    'empty b8 data',           lambda:th('','b8')),
-('b32 data',        'BaseConversionError',    'not in b32',              lambda:th('1az','b32')),
+('b58 data (empty)','BaseConversionError',    'empty base58 data',       lambda:th('','b58')),
+('b8 data (empty)' ,'BaseConversionError',    'empty base8 string data', lambda:th('','b8')),
+('b32 data',        'BaseConversionError',    'not in MMGen base32',     lambda:th('1az','b32')),
 ('pad arg (in)',    'BaseConversionPadError', "illegal value for 'pad'", lambda:fh('ff','b58',pad='foo')),
 ('pad arg (in)',    'BaseConversionPadError', "illegal value for 'pad'", lambda:fh('ff','b58',pad=False)),
 ('pad arg (in)',    'BaseConversionPadError', "illegal value for 'pad'", lambda:fh('ff','b58',pad=True)),
-('seedlen (in)',    'SeedLengthError',        'invalid seed byte length',lambda:fh('ff','b58',pad='seed')),
+('seedlen (in)',    'SeedLengthError',        'invalid byte length',     lambda:fh('ff','b58',pad='seed')),
 ('pad arg (out)',   'BaseConversionPadError', "illegal value for 'pad'", lambda:th('Z','b58',pad='foo')),
 ('pad arg (out)',   'BaseConversionPadError', "illegal value for 'pad'", lambda:th('Z','b58',pad=False)),
 ('pad arg (out)',   'BaseConversionPadError', "illegal value for 'pad'", lambda:th('Z','b58',pad=True)),