class Mongo::Srv::Resolver
Encapsulates the necessary behavior for querying SRV records as required by the driver.
@api private
Constants
- RECORD_PREFIX
@return [ String ] RECORD_PREFIX The prefix prepended to each hostname
before querying SRV records.
Attributes
@return [ Hash ] Resolver options.
Public Class Methods
Creates a new Resolver.
@option opts [ Float ] :timeout The timeout, in seconds, to use for
each DNS record resolution.
@option opts [ Boolean ] :raise_on_invalid Whether or not to raise
an exception if either a record with a mismatched domain is found or if no records are found. Defaults to true.
@option opts [ Hash ] :resolv_options For internal driver use only.
Options to pass through to Resolv::DNS constructor for SRV lookups.
# File lib/mongo/srv/resolver.rb, line 50 def initialize(**opts) @options = opts.freeze @resolver = Resolv::DNS.new(@options[:resolv_options]) @resolver.timeouts = timeout end
Public Instance Methods
Obtains all of the SRV records for a given hostname. If a srv_max_hosts is specified and it is greater than 0, return maximum srv_max_hosts records.
In the event that a record with a mismatched domain is found or no records are found, if the :raise_on_invalid option is true, an exception will be raised, otherwise a warning will be logged.
@param [ String ] hostname The hostname whose records should be obtained. @param [ String | nil ] srv_service_name The SRV service name for the DNS query.
If nil, 'mongodb' is used.
@param [ Integer | nil ] srv_max_hosts The maximum number of records to return.
If this value is nil, return all of the records.
@raise [ Mongo::Error::MismatchedDomain ] If the :raise_in_invalid
Resolver option is true and a record with a domain name that does not match the hostname's is found.
@raise [ Mongo::Error::NoSRVRecords ] If the :raise_in_invalid Resolver
option is true and no records are found.
@return [ Mongo::Srv::Result ] SRV lookup result.
# File lib/mongo/srv/resolver.rb, line 83 def get_records(hostname, srv_service_name=nil, srv_max_hosts=nil) query_name = record_prefix(srv_service_name) + hostname resources = @resolver.getresources(query_name, Resolv::DNS::Resource::IN::SRV) # Collect all of the records into a Result object, raising an error # or logging a warning if a record with a mismatched domain is found. # Note that in the case a warning is raised, the record is _not_ # added to the Result object. result = Srv::Result.new(hostname) resources.each do |record| begin result.add_record(record) rescue Error::MismatchedDomain => e if raise_on_invalid? raise else log_warn(e.message) end end end # If no records are found, either raise an error or log a warning # based on the Resolver's :raise_on_invalid option. if result.empty? if raise_on_invalid? raise Error::NoSRVRecords.new(URI::SRVProtocol::NO_SRV_RECORDS % hostname) else log_warn(URI::SRVProtocol::NO_SRV_RECORDS % hostname) end end # if srv_max_hosts is in [1, #addresses) if (1...result.address_strs.length).include? srv_max_hosts sampled_records = resources.shuffle.first(srv_max_hosts) result = Srv::Result.new(hostname) sampled_records.each { |record| result.add_record(record) } end result end
Obtains the TXT records of a host.
@param [ String ] hostname The host whose TXT records should be obtained.
@return [ nil | String ] URI options string from TXT record
associated with the hostname, or nil if there is no such record.
@raise [ Mongo::Error::InvalidTXTRecord ] If more than one TXT record is found.
# File lib/mongo/srv/resolver.rb, line 131 def get_txt_options_string(hostname) records = @resolver.getresources(hostname, Resolv::DNS::Resource::IN::TXT) if records.empty? return nil end if records.length > 1 msg = "Only one TXT record is allowed: querying hostname #{hostname} returned #{records.length} records" raise Error::InvalidTXTRecord, msg end records[0].strings.join end
Generates the record prefix with a custom SRV service name if it is provided.
@option srv_service_name [ String | nil ] The SRV service name to use
in the record prefix.
@return [ String ] The generated record prefix.
# File lib/mongo/srv/resolver.rb, line 37 def record_prefix(srv_service_name=nil) return srv_service_name ? "_#{srv_service_name}._tcp." : RECORD_PREFIX end
# File lib/mongo/srv/resolver.rb, line 59 def timeout options[:timeout] || Monitor::DEFAULT_TIMEOUT end
Private Instance Methods
Checks whether an error should be raised due to either a record with a mismatched domain being found or no records being found.
@return [ Boolean ] Whether an error should be raised.
# File lib/mongo/srv/resolver.rb, line 152 def raise_on_invalid? @raise_on_invalid ||= @options[:raise_on_invalid] || true end