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Without nserver (or fakeresolve) names were resolved by the C library. 3proxy's own resolver is now the default, with the system's name servers: up to 3 from /etc/resolv.conf, on Windows from the registry (set for the system, set for an interface with an address, Tcpip6 interfaces, then those DHCP gave). With none found, the C library as before. nserver takes up to 3 as well (MAXNSERVERS), a fourth is warned about. The name servers in force belong to the process, not a configuration: nserver lines are kept aside while a configuration is read and replace them only once it is committed, so a reload resolves with those in force until then. Resolutions and dnspr read a copy of them. The system's are read at start, before the configuration and a chroot in it, and are in force while it is read, so its host names resolve with them; read again at a commit, and checked every 5 seconds from the main loop while the default is in force. What cannot be read then (within a chroot) stays as last read. The hosts file, read with them, is imported into tables of its own while the default is in force: its first address of a family for a name. A name is looked up as one nsrecord made first, then the hosts file, then the name cache, then name servers. A changed file replaces what was imported. No name cache is made for it: without nscache nothing is cached, as before. The name cache's keys are host names of any case now: DNS names are. Tests: sysdns, a name of the hosts file answered by dnspr without nserver, in any case, and not with one. Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
84 lines
2.4 KiB
Python
84 lines
2.4 KiB
Python
"""The system's name servers and hosts file as the default resolver: with
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no nserver in a configuration, names in the hosts file are answered from
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it, through the name cache; with nserver lines, the file is not used."""
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import os
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import re
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import sys
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import time
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def hosts_path():
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if sys.platform == "win32":
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return os.path.join(os.environ.get("SystemRoot", r"C:\Windows"),
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"System32", "drivers", "etc", "hosts")
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return "/etc/hosts"
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def hosts_localhost():
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"""Whether the hosts file maps localhost to 127.0.0.1 itself."""
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try:
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with open(hosts_path(), errors="replace") as f:
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for line in f:
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words = line.split("#", 1)[0].split()
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if len(words) > 1 and words[0] == "127.0.0.1" and "localhost" in [w.lower() for w in words[1:]]:
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return True
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except OSError:
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pass
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return False
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def system_nameserver():
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"""Whether there is a name server for 3proxy to find: resolv.conf has
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one, or on Windows the registry is taken to."""
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if sys.platform == "win32":
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return True
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try:
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with open("/etc/resolv.conf") as f:
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return any(re.match(r"nameserver\s+[0-9a-fA-F.:]+\s*$", l.split("#")[0]) for l in f)
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except OSError:
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return False
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def wait(t, port, name):
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deadline = time.time() + 5
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while time.time() < deadline:
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if t.dns_query(port, name):
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return
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def run(t):
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if not hosts_localhost() or not system_nameserver():
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t.skip("no localhost in the hosts file, or no system name server")
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return
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port = t.free_port()
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t.start("sysdns", f"""
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log
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flush
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auth iponly
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allow *
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dnspr -p{port}
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""")
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wait(t, port, "localhost")
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t.eq(["127.0.0.1"], t.dns_query(port, "localhost"),
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"without nserver, a name of the hosts file is answered from it")
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t.eq(["127.0.0.1"], t.dns_query(port, "LocalHost"),
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"whatever its case")
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# with a name server configured, one that answers nothing, the hosts
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# file is not used
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other = t.free_port()
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t.start("sysdns_nserver", f"""
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log
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flush
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nserver 127.0.0.1:{t.free_port()}
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nscache 1024
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auth iponly
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allow *
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dnspr -p{other}
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""")
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wait(t, other, "localhost")
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t.ne(["127.0.0.1"], t.dns_query(other, "localhost") or [],
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"with nserver, the hosts file is not used")
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