import subprocess

def resolve_by_spf(domain):
    output = subprocess.run(["nslookup", "-q=TXT", domain], capture_output=True)
    lines = output.stdout.decode().split('\n')

    result = []

    for line in lines:
        res = line.find('v=spf')

        if res == -1:
            continue

        values = line[res:].split()

        for val in values:
            if val.startswith("include:"):
                result += resolve_by_spf(val[8:].strip())
            
            if val.startswith("ip4:"):
                result.append(val[4:].strip())

        return list(dict.fromkeys(result))

ips = resolve_by_spf("_spf.google.com")

with open('ips.txt', 'a') as out:
    for ip in ips:
        out.write(ip + '\n')