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feat: http fetch tunnel over webrtc datachannel
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,140 @@ | ||
| /** | ||
| * Emulates HTML Fetch API over peer-to-peer | ||
| * DataConnection (WebRTC DataChannel) | ||
| */ | ||
| export class PeerFetch { | ||
| constructor (dataConnection) { | ||
| // the DataConnection that PeerFetch rides on | ||
| this._dataConnection = dataConnection | ||
| // Map of pending requests awaiting responses | ||
| this._requestMap = new Map() | ||
| // incrementing counter to the next available | ||
| // unused ticket number | ||
| // Each request is assigned a ticket | ||
| // which can be used to claim the response | ||
| this._nextAvailableTicket = 0 | ||
| // points to the next ticket assigned to a pending request | ||
| // Requests are processed in FIFO order. | ||
| this._nextTicketInLine = 0 | ||
| this._configureDataConnection() | ||
| } | ||
|
|
||
| /** | ||
| Return the next available ticket number | ||
| and simultaneously increment the ticket counter. | ||
| */ | ||
| _drawNewTicket () { | ||
| return this._nextAvailableTicket++ | ||
| } | ||
|
|
||
| /** | ||
| Move on to next pending ticket | ||
| */ | ||
| _ticketProcessed (ticket) { | ||
| const errorMsg = 'response received out of order!' | ||
| const nextTicket = this._nextTicketInLine | ||
| console.assert( | ||
| ticket === nextTicket, | ||
| { ticket, nextTicket, errorMsg } | ||
| ) | ||
| // remove entry from pending request map | ||
| this._requestMap.delete(ticket) | ||
| this._nextTicketInLine++ | ||
| } | ||
|
|
||
| _configureDataConnection () { | ||
| // Handle incoming data (messages only since this is the signal sender) | ||
| const peerFetch = this | ||
| this._dataConnection.on('data', function (data) { | ||
| console.debug('Remote Peer Data message received (type %s): %s', | ||
| typeof (data), data) | ||
| // we expect data to be a response to a previously sent request message | ||
| const response = data | ||
| const ticket = peerFetch._nextTicketInLine | ||
| console.debug(peerFetch, peerFetch._requestMap, ticket, response) | ||
| // update request map entry with this response | ||
| const pair = peerFetch._requestMap.get(ticket) | ||
| pair.response = response | ||
| }) | ||
| } | ||
|
|
||
| /** | ||
| * REST API over HTTP GET | ||
| */ | ||
| async get ({ url = '/', params = {} }) { | ||
| console.debug('PeerFetch.get', url, params) | ||
| if (params.size > 0) { | ||
| var esc = encodeURIComponent | ||
| var query = Object.keys(params) | ||
| .map(k => esc(k) + '=' + esc(params[k])) | ||
| .join('&') | ||
| url += '?' + query | ||
| } | ||
| const request = { | ||
| url, | ||
| method: 'GET' | ||
| } | ||
| // get a ticket that matches the request | ||
| // and use it to claim the corresponding | ||
| // response when availably | ||
| const ticket = this._pushRequest(request) | ||
| const response = await this._receiveResponse(ticket) | ||
| return response | ||
| } | ||
|
|
||
| _pushRequest (request) { | ||
| const ticket = this._drawNewTicket() | ||
| console.debug(this._requestMap) | ||
| this._requestMap.set(ticket, { request }) | ||
| if (this._requestMap.size === 1) { | ||
| // there are no other pending requests | ||
| // let's send this one on the wire | ||
| this._sendNextRequest(ticket) | ||
| } | ||
| return ticket | ||
| } | ||
|
|
||
| /** | ||
| Send next pending request to remote peer. | ||
| Requests are sent one at a time. | ||
| Only when a previous request response arrives | ||
| is the next request sent across the wire. | ||
| In the future we can look at handling multiple requests | ||
| and responses in parallel over the same data connection or | ||
| even a pool of connections. | ||
| */ | ||
| _sendNextRequest (ticket) { | ||
| const { request } = this._requestMap.get(ticket) | ||
| const jsonRequest = JSON.stringify(request) | ||
| const requestMap = this._requestMap | ||
| console.debug('Sending request to remote peer', | ||
| { requestMap, ticket, request }) | ||
| this._dataConnection.send(jsonRequest) | ||
| } | ||
|
|
||
| async _receiveResponse (ticket) { | ||
| const timeout = 30 * 1000 // 30 seconds | ||
| const timerStart = Date.now() | ||
| let timeElapsed = timerStart | ||
| let request, response | ||
| do { | ||
| ({ request, response } = this._requestMap.get(ticket)) | ||
| if (response) { | ||
| // if (typeof(response) === 'string') { | ||
| this._ticketProcessed(ticket) | ||
| console.debug('Received response', { ticket, request, response }) | ||
| return response | ||
| } | ||
| timeElapsed = Date.now() - timeElapsed | ||
| await sleep(100) | ||
| } while (!response && timeElapsed < timeout) | ||
| if (!response) { | ||
| throw Error('PeerFetch Timeout while waiting for response.') | ||
| } | ||
| } | ||
| } | ||
|
|
||
| function sleep (ms) { | ||
| return new Promise(resolve => setTimeout(resolve, ms)) | ||
| } |
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -1,7 +1,3 @@ | ||
| /** | ||
| Manage plug and play connection to Ambianic Edge. | ||
| */ | ||
|
|
||
| /** | ||
| * Local room management for a peer | ||
| */ | ||
|
|
||
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