Channel
- Ares Channel¶
-
class
pycares.
Channel
([flags, timeout, tries, ndots, tcp_port, udp_port, servers, domains, lookups, sock_state_cb, socket_send_buffer_size, socket_receive_buffer_size, rotate])¶ Parameters: - flags (int) – Flags controlling the behavior of the resolver. See
constants
for available values. - timeout (float) – The number of seconds each name server is given to respond to a query on the first try. The default is five seconds.
- tries (int) – The number of tries the resolver will try contacting each name server before giving up. The default is four tries.
- ndots (int) – The number of dots which must be present in a domain name for it to be queried for “as is” prior to querying for it with the default domain extensions appended. The default value is 1 unless set otherwise by resolv.conf or the RES_OPTIONS environment variable.
- tcp_port (int) – The (TCP) port to use for queries. The default is 53.
- udp_port (int) – The (UDP) port to use for queries. The default is 53.
- servers (list) – List of nameservers to be used to do the lookups.
- domains (list) – The domains to search, instead of the domains specified in resolv.conf or the domain derived from the kernel hostname variable.
- lookup (str) – The lookups to perform for host queries. lookups should be set to a string of the characters “b” or “f”, where “b” indicates a DNS lookup and “f” indicates a lookup in the hosts file.
- sock_state_cb (callable) – A callback function to be invoked when a
socket changes state. Callback signature:
sock_state_cb(self, fd, readable, writable)
- socket_send_buffer_size (int) – Size for the created socket’s send buffer.
- socket_receive_buffer_size (int) – Size for the created socket’s receive buffer.
- rotate (bool) – If set to True, the nameservers are rotated when doing queries.
The c-ares
Channel
provides asynchronous DNS operations.-
gethostbyname
(name, family, callback)¶ Parameters: - name (string) – Name to query.
- family (int) – Socket family.
- callback (callable) – Callback to be called with the result of the query.
Retrieves host information corresponding to a host name from a host database.
Callback signature:
callback(result, errorno)
-
gethostbyaddr
(name, callback)¶ Parameters: - name (string) – Name to query.
- callback (callable) – Callback to be called with the result of the query.
Retrieves the host information corresponding to a network address.
Callback signature:
callback(result, errorno)
-
getnameinfo
(name, port, flags, callback)¶ Parameters: - name (string) – Name to query.
- port (int) – Port of the service to query.
- flags (int) – Query flags, see the NI flags section.
- callback (callable) – Callback to be called with the result of the query.
Provides protocol-independent name resolution from an address to a host name and from a port number to the service name.
Callback signature:
callback(result, errorno)
-
query
(name, query_type, callback)¶ Parameters: - name (string) – Name to query.
- query_type (int) – Type of query to perform.
- callback (callable) – Callback to be called with the result of the query.
- Do a DNS query of the specified type. Available types:
QUERY_TYPE_A
QUERY_TYPE_AAAA
QUERY_TYPE_CNAME
QUERY_TYPE_MX
QUERY_TYPE_NAPTR
QUERY_TYPE_NS
QUERY_TYPE_PTR
QUERY_TYPE_SOA
QUERY_TYPE_SRV
QUERY_TYPE_TXT
Callback signature:
callback(result, errorno)
. The result type varies depending on the query type:- A and AAAA:
ares_query_simple_result
, fields:- host
- ttl
- CNAME:
ares_query_cname_result
, fields:- cname
- ttl
- MX:
ares_query_mx_result
, fields:- host
- priority
- ttl
- NAPTR:
ares_query_naptr_result
, fields:- order
- preference
- flags
- service
- regex
- replacement
- ttl
- NS:
ares_query_ns_result
, fields:- host
- ttl
- PTR:
ares_query_ptr_result
, fields:- name
- ttl
- SOA:
ares_query_soa_result
, fields:- nsmane
- hostmaster
- serial
- refresh
- retry
- expires
- minttl
- ttl
- SRV:
ares_query_srv_result
, fields:- host
- port
- priority
- weight
- ttl
- TXT:
ares_query_txt_result
, fields:- text
- ttl
Note
TTL is not implemented for CNAME, NS and PTR), so it’s set to None.
-
cancel
()¶ Cancel any pending query on this channel. All pending callbacks will be called with ARES_ECANCELLED errorno.
-
destroy
()¶ Destroy the channel. All pending callbacks will be called with ARES_EDESTRUCTION errorno.
-
process_fd
(read_fd, write_fd)¶ Parameters: - read_fd (int) – File descriptor ready to read from.
- write_fd (int) – File descriptor ready to write to.
Process the given file descriptors for read and/or write events.
-
getsock
()¶ Return a tuple containing 2 lists with the file descriptors ready to read and write.
-
timeout
([max_timeout])¶ Parameters: max_timeout (float) – Maximum timeout. Determines the maximum time for which the caller should wait before invoking
process_fd
to process timeouts. If themax_timeout
parameter is specified, it is stored on the channel and the appropriate value is then returned.
-
set_local_ip
(local_ip)¶ Parameters: local_ip (str) – IP address. Set the local IPv4 or IPv6 address from which the queries will be sent.
-
set_local_dev
(local_dev)¶ Parameters: local_dev (str) – Network device name. Set the local ethernet device from which the queries will be sent.
-
servers
¶ List of nameservers to use for DNS queries.
- flags (int) – Flags controlling the behavior of the resolver. See