Encoding and decoding files with txt records

txtrecord_decode.py

#!/usr/bin/env python3
# txtrecord_decode.py [-h] output.png logo.example.com
import dns.resolver # pip3 install dnspython
import base64
import sys
from argparse import ArgumentParser
def parse_records(name):
    _next = ""
    print("{}".format(name), file=sys.stderr)
    q = dns.resolver.query(name,"TXT").response.answer[0]
    out = b""
    for line in sorted(_.strings[0] for _ in q):
        if chr(line[0]) == "{":
            if chr(line[1]) == "n":
                _next = line.split(b"}",1)[1].decode("utf-8")
                continue
            try:
                out += line.split(b"}",1)[1]
            except IndexError:
                pass
    return out, _next

def main():
    parser = ArgumentParser()
    parser.add_argument("output", help="Output filename (or - for stdout)")
    parser.add_argument("domain", help="Target domain")
    args = parser.parse_args()
    name = args.domain
    out = b""
    while True:
        next_out, name = parse_records(name)
        out += next_out
        if not name:
            break

    if args.output == "-":
        sys.stdout.buffer.write(base64.b64decode(out))
        sys.stdout.flush()
    else:
        with open(args.output, "wb") as f:
            f.write(base64.b64decode(out))
    return 0

if __name__ == "__main__":
    sys.exit(main())

txtrecord_encode.py

#!/usr/bin/env python3
# txtrecord_encode.py [-h] [--format '{0} IN TXT "{1}"'] input.png logo.example.com
import base64
import sys
from argparse import ArgumentParser
from textwrap import wrap

def main():
    parser = ArgumentParser()
    parser.add_argument("input", help="Input filename (or - for stdin)")
    parser.add_argument("domain", help="Target domain")
    parser.add_argument("--format", help="DNS record format, where {0} is the target domain (without trailing dot), and {1} is the record text (defaults to bind/named \"{0}. IN TXT '{1}'\")", default="{0}. IN TXT '{1}'")
    args = parser.parse_args()
    if args.input == "-":
        inp = sys.stdin.buffer.read()
    else:
        with open(args.input,"rb") as f:
            inp = f.read()
    enc = base64.b64encode(inp).decode("utf-8")
    tot = len(enc)
    tmp = 0
    for n,block in enumerate(wrap(enc,65000)):
        tmp += len(block)
        print("\n".join(args.format.format((str(n) if n else "") + sys.argv[2], "{}{}".format("{%03d}" % _n, s)) for _n, s in enumerate(wrap(block,249))))
        if tmp != tot:
            print(args.format.format((str(n) if n else "") + sys.argv[2], "{}{}".format("{nxt}", str(n+1) + sys.argv[2] + ".")))
    return 0

if __name__ == "__main__":
    sys.exit(main())

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