def verify_ipaddress(address: Optional[HostAddress]) -> None:
if not address:
raise MKIPAddressLookupError("Host has no IP address configured.")
if address in ["0.0.0.0", "::"]:
raise MKIPAddressLookupError(
"Failed to lookup IP address and no explicit IP address configured")
def cached_dns_lookup(
hostname: HostName,
*,
family: socket.AddressFamily,
is_no_ip_host: bool,
) -> Optional[str]:
cache = _config_cache.get("cached_dns_lookup")
cache_id = hostname, family
# Address has already been resolved in prior call to this function?
try:
return cache[cache_id]
except KeyError:
pass
ip_lookup_cache = _get_ip_lookup_cache()
cached_ip = ip_lookup_cache.get(cache_id)
if cached_ip and config.use_dns_cache:
cache[cache_id] = cached_ip
return cached_ip
if is_no_ip_host:
cache[cache_id] = None
return None
# Now do the actual DNS lookup
try:
ipa = socket.getaddrinfo(hostname, None, family)[0][4][0]
# Update our cached address if that has changed or was missing
if ipa != cached_ip:
console.verbose("Updating %s DNS cache for %s: %s\n" % (family, hostname, ipa))
ip_lookup_cache.update_cache(cache_id, ipa)
cache[cache_id] = ipa # Update in-memory-cache
return ipa
except (MKTerminate, MKTimeout):
# We should be more specific with the exception handler below, then we
# could drop this special handling here
raise
except Exception as e:
# DNS failed. Use cached IP address if present, even if caching
# is disabled.
if cached_ip:
cache[cache_id] = cached_ip
return cached_ip
cache[cache_id] = None
raise MKIPAddressLookupError("Failed to lookup %s address of %s via DNS: %s" % (
{
socket.AF_INET: "IPv4",
socket.AF_INET6: "IPv6"
}[family],
hostname,
e,
))
def _actual_dns_lookup(
*,
host_name: HostName,
family: socket.AddressFamily,
fallback: Optional[HostAddress] = None,
) -> HostAddress:
try:
return socket.getaddrinfo(host_name, None, family)[0][4][0]
except (MKTerminate, MKTimeout):
# We should be more specific with the exception handler below, then we
# could drop this special handling here
raise
except Exception as e:
if fallback:
return fallback
family_str = {socket.AF_INET: "IPv4", socket.AF_INET6: "IPv6"}[family]
raise MKIPAddressLookupError(
f"Failed to lookup {family_str} address of {host_name} via DNS: {e}"
)
def fake_lookup_ip_address(host_config, family=None, for_mgmt_board=True):
raise MKIPAddressLookupError("Failed to ...")
def fake_lookup_ip_address(*_a, **_kw):
raise MKIPAddressLookupError("Failed to ...")
def cached_dns_lookup(
hostname: HostName,
*,
family: socket.AddressFamily,
force_file_cache_renewal: bool,
) -> Optional[str]:
"""Cached DNS lookup in *two* caching layers
1) outer layer:
A *config cache* that caches all calls until the configuration is changed or runtime ends.
Other than activating a changed configuration there is no way to remove cached results during
runtime. Changes made by a differend process will not be noticed.
This layer caches `None` for lookups that failed, after raising the corresponding exception
*once*. Subsequent lookups for this hostname / family combination will not raise an
exception, until the configuration is changed.
2) inner layer:
This layer caches *successful* lookups of host name / IP address
family combinations, and writes them to a file.
Note that after the file is loaded initially, the data in the IPLookupCache is keept in sync
with the file, and itself stored in a dict in the config cache.
Before a new value is writte to file, the file is re-read, as another process might have
changed it.
"""
cache = _config_cache.get("cached_dns_lookup")
cache_id = hostname, family
# Address has already been resolved in prior call to this function?
try:
return cache[cache_id]
except KeyError:
pass
ip_lookup_cache = _get_ip_lookup_cache()
cached_ip = ip_lookup_cache.get(cache_id)
if cached_ip and not force_file_cache_renewal:
cache[cache_id] = cached_ip
return cached_ip
# Now do the actual DNS lookup
try:
ipa = socket.getaddrinfo(hostname, None, family)[0][4][0]
# Update our cached address if that has changed or was missing
if ipa != cached_ip:
console.verbose("Updating %s DNS cache for %s: %s\n" %
(family, hostname, ipa))
ip_lookup_cache.update_cache(cache_id, ipa)
cache[cache_id] = ipa # Update in-memory-cache
return ipa
except (MKTerminate, MKTimeout):
# We should be more specific with the exception handler below, then we
# could drop this special handling here
raise
except Exception as e:
# DNS failed. Use cached IP address if present, even if caching
# is disabled.
if cached_ip:
cache[cache_id] = cached_ip
return cached_ip
cache[cache_id] = None
raise MKIPAddressLookupError(
"Failed to lookup %s address of %s via DNS: %s" % (
{
socket.AF_INET: "IPv4",
socket.AF_INET6: "IPv6"
}[family],
hostname,
e,
))