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Author: javascript-2020

utils/gcloud/generate-token-from-service-account-keyfile/generate.js

@@ -0,0 +1,149 @@
+
+
+
+        async function generate(keyfile){
+              
+
+
+              var clientEmail       = keyfile.client_email;
+              var privateKeyPem     = keyfile.private_key.replace(/\\n/g,'\n');
+              var scope             = 'https://www.googleapis.com/auth/devstorage.read_write';
+              
+              var assertion         = await buildJwtAssertion({clientEmail,privateKeyPem,scope});
+              var json              = await exchangeForAccessToken(assertion);
+              var token             = json.access_token;
+
+              
+              return {json,token};
+              
+      
+            
+              function base64url(input){
+              
+                    let bytes;
+                    
+                    if(typeof input=='string'){
+                          bytes   = encoder.encode(input);
+                    }else if(input instanceof ArrayBuffer){
+                          bytes   = new Uint8Array(input);
+                    }else if(ArrayBuffer.isView(input)){
+                          bytes   = new Uint8Array(input.buffer, input.byteOffset, input.byteLength);
+                    }else{
+                          throw new TypeError('Unsupported input');
+                    }
+                    
+                    var bin   = '';
+                    for(var i=0;i<bytes.length;i++){
+                      
+                          bin  += String.fromCharCode(bytes[i]);
+                          
+                    }//for
+                    
+                    var str   = btoa(bin).replace(/\+/g, '-').replace(/\//g, '_').replace(/=+$/g, '');
+                    return str;
+                
+              }//base64url
+      
+            
+              function pemToArrayBuffer(pem){
+              
+                    const b64   = pem.replace(/-----BEGIN [^-]+-----/g, '')
+                                        .replace(/-----END [^-]+-----/g, '')
+                                        .replace(/\s+/g, '');
+                    const raw   = atob(b64);
+                    const buf   = new Uint8Array(raw.length);
+                    
+                    for(let i=0;i<raw.length;i++){
+                      
+                          buf[i]    = raw.charCodeAt(i);
+                            
+                    }//fpr
+                    
+                    return buf.buffer;
+                    
+              }//pem_buf
+      
+            
+              async function importPkcs8PrivateKey(pem) {
+              
+                    var keyData   = pemToArrayBuffer(pem);
+                    var key       = await crypto.subtle.importKey('pkcs8',keyData,{name:'RSASSA-PKCS1-v1_5',hash:'SHA-256'},false,['sign']);
+                    return key
+                    
+              }//import
+      
+            
+              async function signRS256(privateKey, dataToSign) {
+              
+                    var dataBytes   = encoder.encode(dataToSign);
+                    var sig         = await crypto.subtle.sign({name:'RSASSA-PKCS1-v1_5'},privateKey,dataBytes);
+                    var uint8       = new Uint8Array(sig);
+                    return uint8;
+                    
+              }//sign
+      
+            
+              async function buildJwtAssertion({clientEmail,privateKeyPem,scope,aud='https://oauth2.googleapis.com/token'}){
+              
+                    var key               = await importPkcs8PrivateKey(privateKeyPem);
+                
+                    var now               = Math.floor(Date.now()/1000);
+                    var header            = {alg:'RS256',typ:'JWT'};
+                    var payload           = {
+                                                  iss     : clientEmail,
+                                                  scope   : Array.isArray(scope) ? scope.join(' ') : scope,
+                                                  aud     : aud,
+                                                  iat     : now,
+                                                  exp     : now+3600, // 1 hour max
+                                            };
+                
+                    var encodedHeader     = base64url(JSON.stringify(header));
+                    var encodedPayload    = base64url(JSON.stringify(payload));
+                    var unsigned          = `${encodedHeader}.${encodedPayload}`;
+                
+                    var sig               = await signRS256(key,unsigned);
+                    var encodedSig        = base64url(sig);
+                    var str               = `${unsigned}.${encodedSig}`;
+                    return str
+                    
+              }//build
+            
+              
+              async function exchangeForAccessToken(assertion) {
+              
+                    var url       = 'https://oauth2.googleapis.com/token';
+                    var body      = new URLSearchParams({grant_type:'urn:ietf:params:oauth:grant-type:jwt-bearer',assertion});
+                    var headers   = {'Content-Type':'application/x-www-form-urlencoded'};
+                    
+                    var err;
+                    try{
+                      
+                          var res       = await fetch(url,{method:'post',headers,body});
+                          
+                    }//try
+                    catch(err2){
+                      
+                          err   = err2;
+                          
+                    }//catch
+                    if(err){
+                                                                                console.error(err);
+                          disp(err.toString());
+                          return;
+                    }
+                    
+                    if(!res.ok){
+                          throw new Error(`Token exchange failed: ${res.status} ${res.statusText} ${await res.text()}`);
+                    }
+                                                                                // { access_token, token_type, expires_in }
+                    var json    = await res.json();
+                    return json;
+                    
+              }//exchange
+            
+        
+        }//generate
+
+
+
+