Commit iniziale

node_modules/@azure/keyvault-common/dist/browser/tokenCycler.js

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+// Copyright (c) Microsoft Corporation.
+// Licensed under the MIT License.
+import { delay } from "@azure/core-util";
+// Default options for the cycler if none are provided
+export const DEFAULT_CYCLER_OPTIONS = {
+    forcedRefreshWindowInMs: 1000, // Force waiting for a refresh 1s before the token expires
+    retryIntervalInMs: 3000, // Allow refresh attempts every 3s
+    refreshWindowInMs: 1000 * 60 * 2, // Start refreshing 2m before expiry
+};
+/**
+ * Converts an an unreliable access token getter (which may resolve with null)
+ * into an AccessTokenGetter by retrying the unreliable getter in a regular
+ * interval.
+ *
+ * @param getAccessToken - A function that produces a promise of an access token that may fail by returning null.
+ * @param retryIntervalInMs - The time (in milliseconds) to wait between retry attempts.
+ * @param refreshTimeout - The timestamp after which the refresh attempt will fail, throwing an exception.
+ * @returns - A promise that, if it resolves, will resolve with an access token.
+ */
+async function beginRefresh(getAccessToken, retryIntervalInMs, refreshTimeout) {
+    // This wrapper handles exceptions gracefully as long as we haven't exceeded
+    // the timeout.
+    async function tryGetAccessToken() {
+        if (Date.now() < refreshTimeout) {
+            try {
+                return await getAccessToken();
+            }
+            catch (_a) {
+                return null;
+            }
+        }
+        else {
+            const finalToken = await getAccessToken();
+            // Timeout is up, so throw if it's still null
+            if (finalToken === null) {
+                throw new Error("Failed to refresh access token.");
+            }
+            return finalToken;
+        }
+    }
+    let token = await tryGetAccessToken();
+    while (token === null) {
+        await delay(retryIntervalInMs);
+        token = await tryGetAccessToken();
+    }
+    return token;
+}
+/**
+ * Creates a token cycler from a credential, scopes, and optional settings.
+ *
+ * A token cycler represents a way to reliably retrieve a valid access token
+ * from a TokenCredential. It will handle initializing the token, refreshing it
+ * when it nears expiration, and synchronizes refresh attempts to avoid
+ * concurrency hazards.
+ *
+ * @param credential - the underlying TokenCredential that provides the access
+ * token
+ * @param tokenCyclerOptions - optionally override default settings for the cycler
+ *
+ * @returns - a function that reliably produces a valid access token
+ */
+export function createTokenCycler(credential, tokenCyclerOptions) {
+    let refreshWorker = null;
+    let token = null;
+    let tenantId;
+    const options = Object.assign(Object.assign({}, DEFAULT_CYCLER_OPTIONS), tokenCyclerOptions);
+    /**
+     * This little holder defines several predicates that we use to construct
+     * the rules of refreshing the token.
+     */
+    const cycler = {
+        /**
+         * Produces true if a refresh job is currently in progress.
+         */
+        get isRefreshing() {
+            return refreshWorker !== null;
+        },
+        /**
+         * Produces true if the cycler SHOULD refresh (we are within the refresh
+         * window and not already refreshing)
+         */
+        get shouldRefresh() {
+            var _a;
+            if (cycler.isRefreshing) {
+                return false;
+            }
+            if ((token === null || token === void 0 ? void 0 : token.refreshAfterTimestamp) && token.refreshAfterTimestamp < Date.now()) {
+                return true;
+            }
+            return ((_a = token === null || token === void 0 ? void 0 : token.expiresOnTimestamp) !== null && _a !== void 0 ? _a : 0) - options.refreshWindowInMs < Date.now();
+        },
+        /**
+         * Produces true if the cycler MUST refresh (null or nearly-expired
+         * token).
+         */
+        get mustRefresh() {
+            return (token === null || token.expiresOnTimestamp - options.forcedRefreshWindowInMs < Date.now());
+        },
+    };
+    /**
+     * Starts a refresh job or returns the existing job if one is already
+     * running.
+     */
+    function refresh(scopes, getTokenOptions) {
+        var _a;
+        if (!cycler.isRefreshing) {
+            // We bind `scopes` here to avoid passing it around a lot
+            const tryGetAccessToken = () => credential.getToken(scopes, getTokenOptions);
+            // Take advantage of promise chaining to insert an assignment to `token`
+            // before the refresh can be considered done.
+            refreshWorker = beginRefresh(tryGetAccessToken, options.retryIntervalInMs, 
+            // If we don't have a token, then we should timeout immediately
+            (_a = token === null || token === void 0 ? void 0 : token.expiresOnTimestamp) !== null && _a !== void 0 ? _a : Date.now())
+                .then((_token) => {
+                refreshWorker = null;
+                token = _token;
+                tenantId = getTokenOptions.tenantId;
+                return token;
+            })
+                .catch((reason) => {
+                // We also should reset the refresher if we enter a failed state.  All
+                // existing awaiters will throw, but subsequent requests will start a
+                // new retry chain.
+                refreshWorker = null;
+                token = null;
+                tenantId = undefined;
+                throw reason;
+            });
+        }
+        return refreshWorker;
+    }
+    return async (scopes, tokenOptions) => {
+        //
+        // Simple rules:
+        // - If we MUST refresh, then return the refresh task, blocking
+        //   the pipeline until a token is available.
+        // - If we SHOULD refresh, then run refresh but don't return it
+        //   (we can still use the cached token).
+        // - Return the token, since it's fine if we didn't return in
+        //   step 1.
+        //
+        const hasClaimChallenge = Boolean(tokenOptions.claims);
+        const tenantIdChanged = tenantId !== tokenOptions.tenantId;
+        if (hasClaimChallenge) {
+            // If we've received a claim, we know the existing token isn't valid
+            // We want to clear it so that that refresh worker won't use the old expiration time as a timeout
+            token = null;
+        }
+        // If the tenantId passed in token options is different to the one we have
+        // Or if we are in claim challenge and the token was rejected and a new access token need to be issued, we need to
+        // refresh the token with the new tenantId or token.
+        const mustRefresh = tenantIdChanged || hasClaimChallenge || cycler.mustRefresh;
+        if (mustRefresh) {
+            return refresh(scopes, tokenOptions);
+        }
+        if (cycler.shouldRefresh) {
+            refresh(scopes, tokenOptions);
+        }
+        return token;
+    };
+}
+//# sourceMappingURL=tokenCycler.js.map