nsISupports
Last changed in Gecko 1.9.1 (Firefox 3.5 / Thunderbird 3.0 / SeaMonkey 2.0)Implemented by: @mozilla.org/network/dns-service;1. To access the service, use:
var dnsService = Components.classes["@mozilla.org/network/dns-service;1"]
.createInstance(Components.interfaces.nsIDNSService);
Note: Starting in Gecko 7.0, the "happy eyeballs" strategy is used to reduce lengthy timeouts when attempting backup connections during attempts to connect from clients that have broken IPv6 connectivity. This is done by disabling IPv6 on backup connections.
Method overview
nsICancelable asyncResolve(in AUTF8String aHostName, in unsigned long aFlags, in nsIDNSListener aListener, in nsIEventTarget aListenerTarget); |
void init(); Obsolete since Gecko 1.8 |
nsIDNSRecord resolve(in AUTF8String aHostName, in unsigned long aFlags); |
void shutdown(); Obsolete since Gecko 1.8 |
Attributes
| Attribute | Type | Description |
myHostName |
AUTF8String |
Read only. |
Constants
Resolve flag constants
Various flags that may be ORed together to form the aFlags parameter passed to asyncResolve() and resolve().
| Constant | Value | Description |
RESOLVE_BYPASS_CACHE |
(1 << 0) |
This flag suppresses the internal DNS lookup cache. |
RESOLVE_CANONICAL_NAME |
(1 << 1) |
The canonical name of the specified host will be queried. |
RESOLVE_PRIORITY_MEDIUM |
(1 << 2) |
The query is given medium priority. If used with low, medium takes precedence. |
RESOLVE_PRIORITY_LOW |
(1 << 3) |
The query is given lower priority. If used with medium, medium takes precedence. |
RESOLVE_SPECULATE |
(1 << 4) |
Indicates request is speculative. Speculative requests return errors if prefetching is disabled by configuration. |
RESOLVE_DISABLE_IPV6 |
(1 << 5) |
If this flag is set, only IPv4 addresses will be returned by asyncResolve() and resolve(). |
Methods
asyncResolve()
Begins off an asynchronous host lookup. A specified nsIDNSListener is invoked when the resolution process is completed.
nsICancelable asyncResolve( in AUTF8String aHostName, in unsigned long aFlags, in nsIDNSListener aListener, in nsIEventTarget aListenerTarget );
Parameters
-
aHostName - The host name or IP-address-literal to resolve.
-
aFlags - A bitwise OR of the Resolve flag constants.
-
aListener - The listener to be notified when the result is available.
-
aListenerTarget -
Optional parameter (may be
null). If notnull, this parameter specifies thensIEventTargetof the thread on which the listener's onLookupComplete should be called. If this parameter isnull, then onLookupComplete will be called on an unspecified thread (possibly recursively).
Return value
An object that can be used to cancel the host lookup.
init()
Called to initialize the DNS service.
void init();
Parameters
None.
resolve()
Called to synchronously resolve a host name. Warning this method may block the calling thread for a long period of time. It is extremely unwise to call this function on the User Interface thread of an application.
nsIDNSRecord resolve( in AUTF8String aHostName, in unsigned long aFlags );
Parameters
-
aHostName - The host name or IP-address-literal to resolve.
-
aFlags - A bitwise OR of the Resolve flag constants.
Return value
DNS record corresponding to the given host name.
Exceptions thrown
-
NS_ERROR_UNKNOWN_HOST - If host could not be resolved.
shutdown()
Called to shutdown the DNS service. Any pending asynchronous requests will be canceled, and the local cache of DNS records will be cleared.
void shutdown();
Parameters
None.
Example
let DnsService = Components.classes["@mozilla.org/network/dns-service;1"]
.createInstance(Components.interfaces.nsIDNSService);
let Thread = Components.classes["@mozilla.org/thread-manager;1"]
.getService(Components.interfaces.nsIThreadManager).currentThread;
let host = "www.mozilla.org";
let Listener = {
onLookupComplete: function(request, record, status) {
if (!Components.isSuccessCode(status)) {
// Handle error here
return;
}
let address = record.getNextAddrAsString();
console.log(host + " = " + address);
}
};
DnsService.asyncResolve(host, 0, Listener, Thread);