contrib: Improvements to hardcoded seeds scripts

- Moved all seed related scripts to contrib/seeds for consistency
- Updated `makeseeds.py` to handle IPv6 and onions, fix regular
  expression for recent Bitcoin Core versions
- Fixed a bug in `generate-seeds.py` with regard to IPv6 parsing

contrib/seeds/generate-seeds.py

@@ -0,0 +1,138 @@
+#!/usr/bin/python
+# Copyright (c) 2014 Wladmir J. van der Laan
+# Distributed under the MIT software license, see the accompanying
+# file COPYING or http://www.opensource.org/licenses/mit-license.php.
+'''
+Script to generate list of seed nodes for chainparams.cpp.
+
+This script expects two text files in the directory that is passed as an
+argument:
+
+    nodes_main.txt
+    nodes_test.txt
+
+These files must consist of lines in the format 
+
+    <ip>
+    <ip>:<port>
+    [<ipv6>]
+    [<ipv6>]:<port>
+    <onion>.onion
+    0xDDBBCCAA (IPv4 little-endian old pnSeeds format)
+
+The output will be two data structures with the peers in binary format:
+
+   static SeedSpec6 pnSeed6_main[]={
+   ...
+   }
+   static SeedSpec6 pnSeed6_test[]={
+   ...
+   }
+
+These should be pasted into `src/chainparamsseeds.h`.
+'''
+from __future__ import print_function, division
+from base64 import b32decode
+from binascii import a2b_hex
+import sys, os
+import re
+
+# ipv4 in ipv6 prefix
+pchIPv4 = bytearray([0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0xff, 0xff])
+# tor-specific ipv6 prefix
+pchOnionCat = bytearray([0xFD,0x87,0xD8,0x7E,0xEB,0x43])
+
+def name_to_ipv6(addr):
+    if len(addr)>6 and addr.endswith('.onion'):
+        vchAddr = b32decode(addr[0:-6], True)
+        if len(vchAddr) != 16-len(pchOnionCat):
+            raise ValueError('Invalid onion %s' % s)
+        return pchOnionCat + vchAddr
+    elif '.' in addr: # IPv4
+        return pchIPv4 + bytearray((int(x) for x in addr.split('.')))
+    elif ':' in addr: # IPv6
+        sub = [[], []] # prefix, suffix
+        x = 0
+        addr = addr.split(':')
+        for i,comp in enumerate(addr):
+            if comp == '':
+                if i == 0 or i == (len(addr)-1): # skip empty component at beginning or end
+                    continue
+                x += 1 # :: skips to suffix
+                assert(x < 2)
+            else: # two bytes per component
+                val = int(comp, 16)
+                sub[x].append(val >> 8)
+                sub[x].append(val & 0xff)
+        nullbytes = 16 - len(sub[0]) - len(sub[1])
+        assert((x == 0 and nullbytes == 0) or (x == 1 and nullbytes > 0))
+        return bytearray(sub[0] + ([0] * nullbytes) + sub[1])
+    elif addr.startswith('0x'): # IPv4-in-little-endian
+        return pchIPv4 + bytearray(reversed(a2b_hex(addr[2:])))
+    else:
+        raise ValueError('Could not parse address %s' % addr)
+
+def parse_spec(s, defaultport):
+    match = re.match('\[([0-9a-fA-F:]+)\](?::([0-9]+))?$', s)
+    if match: # ipv6
+        host = match.group(1)
+        port = match.group(2)
+    elif s.count(':') > 1: # ipv6, no port
+        host = s
+        port = ''
+    else:
+        (host,_,port) = s.partition(':')
+
+    if not port:
+        port = defaultport
+    else:
+        port = int(port)
+
+    host = name_to_ipv6(host)
+
+    return (host,port)
+
+def process_nodes(g, f, structname, defaultport):
+    g.write('static SeedSpec6 %s[] = {\n' % structname)
+    first = True
+    for line in f:
+        comment = line.find('#')
+        if comment != -1:
+            line = line[0:comment]
+        line = line.strip()
+        if not line:
+            continue
+        if not first:
+            g.write(',\n')
+        first = False
+
+        (host,port) = parse_spec(line, defaultport)
+        hoststr = ','.join(('0x%02x' % b) for b in host)
+        g.write('    {{%s}, %i}' % (hoststr, port))
+    g.write('\n};\n')
+
+def main():
+    if len(sys.argv)<2:
+        print(('Usage: %s <path_to_nodes_txt>' % sys.argv[0]), file=sys.stderr)
+        exit(1)
+    g = sys.stdout
+    indir = sys.argv[1]
+    g.write('#ifndef BITCOIN_CHAINPARAMSSEEDS_H\n')
+    g.write('#define BITCOIN_CHAINPARAMSSEEDS_H\n')
+    g.write('/**\n')
+    g.write(' * List of fixed seed nodes for the bitcoin network\n')
+    g.write(' * AUTOGENERATED by contrib/seeds/generate-seeds.py\n')
+    g.write(' *\n')
+    g.write(' * Each line contains a 16-byte IPv6 address and a port.\n')
+    g.write(' * IPv4 as well as onion addresses are wrapped inside a IPv6 address accordingly.\n')
+    g.write(' */\n')
+    with open(os.path.join(indir,'nodes_main.txt'),'r') as f:
+        process_nodes(g, f, 'pnSeed6_main', 8333)
+    g.write('\n')
+    with open(os.path.join(indir,'nodes_test.txt'),'r') as f:
+        process_nodes(g, f, 'pnSeed6_test', 18333)
+    g.write('#endif // BITCOIN_CHAINPARAMSSEEDS_H\n')
+            
+if __name__ == '__main__':
+    main()
+