move netstring() and split_netstring() into a separate util.netstring module

src/allmydata/dirnode.py

@@ -14,34 +14,10 @@ from allmydata.checker_results import DeepCheckResults, \
 from allmydata.util import hashutil, mathutil, base32, log
 from allmydata.util.hashutil import netstring
 from allmydata.util.limiter import ConcurrencyLimiter
+from allmydata.util.netstring import split_netstring
 from allmydata.uri import NewDirectoryURI
 from pycryptopp.cipher.aes import AES
 
-def split_netstring(data, numstrings, allow_leftover=False):
-    """like string.split(), but extracts netstrings. If allow_leftover=False,
-    returns numstrings elements, and throws ValueError if there was leftover
-    data. If allow_leftover=True, returns numstrings+1 elements, in which the
-    last element is the leftover data (possibly an empty string)"""
-    elements = []
-    assert numstrings >= 0
-    while data:
-        colon = data.index(":")
-        length = int(data[:colon])
-        string = data[colon+1:colon+1+length]
-        assert len(string) == length
-        elements.append(string)
-        assert data[colon+1+length] == ","
-        data = data[colon+1+length+1:]
-        if len(elements) == numstrings:
-            break
-    if len(elements) < numstrings:
-        raise ValueError("ran out of netstrings")
-    if allow_leftover:
-        return tuple(elements + [data])
-    if data:
-        raise ValueError("leftover data in netstrings")
-    return tuple(elements)
-
 class Deleter:
     def __init__(self, node, name, must_exist=True):
         self.node = node