cUrlClient


Index:
Articles
Classes
Hooks

Quick navigation:
cArrowEntity
cBeaconEntity
cBlockArea
cBlockEntity
cBlockEntityWithItems
cBlockInfo
cBoundingBox
cBrewingstandEntity
cChatColor
cChestEntity
cChunkDesc
cClientHandle
cCommandBlockEntity
cCompositeChat
cCraftingGrid
cCraftingRecipe
cCryptoHash
cCuboid
cDispenserEntity
cDropperEntity
cDropSpenserEntity
cEnchantments
cEntity
cEntityEffect
cExpBottleEntity
cFile
cFireChargeEntity
cFireworkEntity
cFloater
cFlowerPotEntity
cFurnaceEntity
cGhastFireballEntity
cHangingEntity
cHopperEntity
cIniFile
cInventory
cItem
cItemFrame
cItemGrid
cItems
cJson
cJukeboxEntity
cLineBlockTracer
cLuaWindow
cMap
cMapManager
cMobHeadEntity
cMobSpawnerEntity
cMojangAPI
cMonster
cNetwork
cNoteEntity
cObjective
cPainting
cPawn
cPickup
cPlayer
cPlugin
cPluginLua
cPluginManager
cProjectileEntity
cRankManager
cRoot
cScoreboard
cServer
cServerHandle
cSignEntity
cSplashPotionEntity
cStatManager
cStringCompression
cTCPLink
cTeam
cThrownEggEntity
cThrownEnderPearlEntity
cThrownSnowballEntity
cTNTEntity
cTracer
cUDPEndpoint
cUrlClient
cUrlParser
cWebAdmin
cWindow
cWitherSkullEntity
cWorld
HTTPFormData
HTTPRequest
HTTPTemplateRequest
ItemCategory
lxp
sqlite3
TakeDamageInfo
tolua
Vector3d
Vector3f
Vector3i
Globals

Contents


cUrlClient class

Implements high-level asynchronous access to URLs, such as downloading webpages over HTTP(S).

Note that unlike other languages' URL access libraries, this class implements asynchronous requests. This means that the functions only start a request and return immediately. The request is then fulfilled in the background, while the server continues to run. The response is delivered back to the plugin using callbacks. This allows the plugin to start requests and not block the server until the response is received.

The functions that make network requests are all static and have a dual interface. Either you can use a single callback function, which gets called once the entire response is received or an error is encountered. Or you can use a table of callback functions, each function being called whenever the specific event happens during the request and response lifetime. See the Simple Callback and Callback Table chapters later on this page for details and examples.

All the request function also support optional parameters for further customization of the request - the Headers parameter specifies additional HTTP headers that are to be sent (as a dictionary-table of key -> value), the RequestBody parameter specifying the optional body of the request (used mainly for POST and PUT requests), and an Options parameter specifying additional options specific to the protocol used.


Functions

NameParametersReturn valueNotes
Delete
URLstring
Callbacksfunction
IsSuccessboolean
ErrorMessaggestring
(STATIC) Starts a HTTP DELETE request. Alias for Request("DELETE", ...). Returns true on succes, false and error message on immediate failure (unparsable URL etc.).
Delete
URLstring
Callbackstable
Headerstable
RequestBodystring
Optionstable
IsSuccessboolean
ErrorMessaggestring
(STATIC) Starts a HTTP DELETE request. Alias for Request("DELETE", ...). Returns true on succes, false and error message on immediate failure (unparsable URL etc.).
Get
URLstring
Callbackstable
Headerstable
RequestBodystring
Optionstable
IsSuccessboolean
ErrMsgstring
(STATIC) Starts a HTTP GET request. Alias for Request("GET", ...). Returns true on succes, false and error message on immediate failure (unparsable URL etc.).
Get
URLstring
Callbacksfunction
IsSuccessboolean
ErrMsgstring
(STATIC) Starts a HTTP GET request. Alias for Request("GET", ...). Returns true on succes, false and error message on immediate failure (unparsable URL etc.).
Post
URLstring
Callbackstable
Headerstable
RequestBodystring
Optionstable
IsSuccessboolean
ErrMsgstring
(STATIC) Starts a HTTP POST request. Alias for Request("POST", ...). Returns true on succes, false and error message on immediate failure (unparsable URL etc.).
Post
URLstring
Callbacksfunction
IsSuccessboolean
ErrMsgstring
(STATIC) Starts a HTTP POST request. Alias for Request("POST", ...). Returns true on succes, false and error message on immediate failure (unparsable URL etc.).
Put
URLstring
Callbacksfunction
IsSuccessboolean
ErrMsgstring
(STATIC) Starts a HTTP PUT request. Alias for Request("PUT", ...). Returns true on succes, false and error message on immediate failure (unparsable URL etc.).
Put
URLstring
Callbackstable
Headerstable
RequestBodystring
Optionstable
IsSuccessboolean
ErrMsgstring
(STATIC) Starts a HTTP PUT request. Alias for Request("PUT", ...). Returns true on succes, false and error message on immediate failure (unparsable URL etc.).
Request
Methodstring
URLstring
Callbackstable
Headerstable
RequestBodystring
Optionstable
IsSuccessboolean
ErrMsgstring
(STATIC) Starts a request with the specified Method. Returns true on succes, false and error message on immediate failure (unparsable URL etc.).

Simple Callback

When you don't need fine control for receiving the requests and are interested only in the result, you can use the simple callback approach. Pass a single function as the Callback parameter, the function will get called when the response is fully processed, either with the body of the response, or with an error message:
cUrlClient:Get(url,
	function (a_Body, a_Data)
		if (a_Body) then
			-- Response received correctly, a_Body contains the entire response body,
			-- a_Data is a dictionary-table of the response's HTTP headers
		else
			-- There was an error, a_Data is the error message string
		end
	end
)

Callback Table

To provide complete control over the request and response handling, Cuberite allows plugins to pass a table of callbacks as the Callback parameter. Then the respective functions are called for their respective events during the lifetime of the request and response. This way it is possible to process huge downloads that wouldn't fit into memory otherwise, or display detailed progress.

Each callback function receives a "self" as its first parameter, this allows the functions to access the Callback table and any of its other members, allowing the use of Lua object idiom for the table. See this forum post for an example.

The following callback functions are used by Cuberite. Any callback that is not assigned is silently ignored. The table may also contain other functions and other values, those are silently ignored.

CallbackParamsNotes
OnConnectedself, cTCPLink, RemoteIP, RemotePortCalled when the connection to the remote host is established. Note that current implementation doesn't provide the cTCPLink parameter and passes nil instead.
OnCertificateReceivedselfCalled for HTTPS URLs when the server's certificate is received. If the callback returns anything else than true, the connection is aborted. Note that the current implementation doesn't provide the certificate because there is no representation for the cert in Lua.
OnTlsHandshakeCompletedselfCalled for HTTPS URLs when the TLS is established on the connection.
OnRequestSentselfCalled after the entire request is sent to the server.
OnStatusLineself, HttpVersion, StatusCode, RestThe initial line of the response has been parsed. HttpVersion is typically "HTTP/1.1", StatusCode is the numerical HTTP status code reported by the server (200 being OK), Rest is the rest of the line, usually a short message in case of an error.
OnHeaderself, Name, ValueA new HTTP response header line has been received.
OnHeadersFinishedself, AllHeadersAll HTTP response headers have been parsed. AllHeaders is a dictionary-table containing all the headers received.
OnBodyDataself, DataA piece of the response body has been received. This callback is called repeatedly until the entire body is reported through its Data parameter.
OnBodyFinishedselfThe entire response body has been reported by OnBodyData(), the response has finished.
OnErrorself, ErrorMsgCalled whenever an error is detected. After this call, no other callback will get called.
OnRedirectingself, NewUrlCalled if the server returned a valid redirection HTTP status code and a Location header, and redirection is allowed by the Options.

The following example is adapted from the Debuggers plugin's "download" command, it downloads the contents of an URL into a file.

function HandleConsoleDownload(a_Split)  -- Console command handler
	-- Read the params from the command:
	local url = a_Split[2]
	local fnam = a_Split[3]
	if (not(url) or not(fnam)) then
		return true, "Missing parameters. Usage: download  "
	end

	-- Define the cUrlClient callbacks
	local callbacks =
	{
		OnStatusLine = function (self, a_HttpVersion, a_Status, a_Rest)
			-- Only open the output file if the server reports a success:
			if (a_Status ~= 200) then
				LOG("Cannot download " .. url .. ", HTTP error code " .. a_Status)
				return
			end
			local f, err = io.open(fnam, "wb")
			if not(f) then
				LOG("Cannot download " .. url .. ", error opening the file " .. fnam .. ": " .. (err or ""))
				return
			end
			self.m_File = f
		end,

		OnBodyData = function (self, a_Data)
			-- If the file has been opened, write the data:
			if (self.m_File) then
				self.m_File:write(a_Data)
			end
		end,

		OnBodyFinished = function (self)
			-- If the file has been opened, close it and report success
			if (self.m_File) then
				self.m_File:close()
				LOG("File " .. fnam .. " has been downloaded.")
			end
		end,
	}

	-- Start the URL download:
	local isSuccess, msg = cUrlClient:Get(url, callbacks)
	if not(isSuccess) then
		LOG("Cannot start an URL download: " .. (msg or ""))
		return true
	end
	return true
end

Options

The requests support the following options, specified in the optional Options table parameter:
Option nameDescription
MaxRedirectsMaximum number of HTTP redirects that the cUrlClient will follow. If the server still reports a redirect after reaching this many redirects, the cUrlClient reports an error. May be specified as either a number or a string parsable into a number. Default: 30.
OwnCertThe client certificate to use, if requested by the server. A string containing a PEM- or DER-encoded cert is expected.
OwnPrivKeyThe private key appropriate for OwnCert. A string containing a PEM- or DER-encoded private key is expected.
OwnPrivKeyPasswordThe password for OwnPrivKey. If not present or empty, no password is assumed.

Redirection:

  • If a redirect is received, and redirection is allowed by MaxRedirects, the redirection is reported via OnRedirecting() callback and the request is restarted at the redirect URL, without reporting any of the redirect's headers nor body.
  • If a redirect is received and redirection is not allowed (maximum redirection attempts have been reached), the OnRedirecting() callback is called with the redirect URL and then the request terminates with an OnError() callback, without reporting the redirect's headers nor body.
Generated on 2017-02-28 13:00:06, Build ID Unknown, Commit approx: efa5d449bddadf74d59d0399a0c804f53bd6a99c