Adding a customizable sas expiracy

bySaS/index.test.ts

@@ -2,6 +2,7 @@ import func from "./index";
 import { Context, HttpRequest } from "@azure/functions";
 import { Substitute } from "@fluffy-spoon/substitute";
 import { env } from "process";
+import { decode } from "querystring";
 // Manually load up env variables, as the func runtime would
 //require("dotenv-safe").config();
 describe("Unit test bySas", () => {
@@ -35,16 +36,33 @@ describe("Unit test bySas", () => {
     });
   });
 
-  describe("Ideal case", () => {
-    it("Basic", async () => {
+  /**
+   * Azurite must be running !
+   */
+  describe.each([
+    ["None", undefined],
+    ["SAS_LIMIT_HOURS", 6],
+  ])("Adding '%s' to env", (varName, value) => {
+    it("Full test", async () => {
+      env[varName] = String(value);
+      const DEFAULT_SAS_LIMIT = 24;
       const [context, request] = formatUploadRequest("test", null, {
         "x-forwarded-for": "1.1.1.1",
       });
       const response = await func(context, request);
       expect(response.status).toBe(200);
       console.log(response.body);
       expect(response.body).toBeDefined();
-    }, 10000);
+      const qs = decode(response.body.split("?")[1]);
+      // Checking sas validity span. When not provided this value should be 24h
+      const sasValidFrom = new Date(qs.st as string);
+      const sasValidTo = new Date(qs.se as string);
+      const timeDiff = sasValidTo.getTime() - sasValidFrom.getTime();
+      expect(Math.round(timeDiff / 1000 / 3600)).toBe(
+        value ?? DEFAULT_SAS_LIMIT
+      );
+      //expect(response.body)
+    }, 15000);
   });
 });
 

bySaS/index.ts

@@ -13,7 +13,9 @@ import {
 } from "@azure/storage-blob";
 import { v4 as uuidv4 } from "uuid";
 import HTTP_CODES from "http-status-enum";
-import { formatReply } from "../common/index";
+import { formatReply, getEnvVar } from "../common/index";
+
+const DEFAULT_HOURS_LIMIT = 24;
 
 export default async function httpTrigger(
   context: Context,
@@ -48,8 +50,20 @@ export default async function httpTrigger(
     });
     return formatReply(`Unexpected error.`, HTTP_CODES.INTERNAL_SERVER_ERROR);
   }
+
+  const hoursLimit = getEnvVar<number>(
+    "SAS_LIMIT_HOURS",
+    DEFAULT_HOURS_LIMIT,
+    context
+  );
+
   // @TODO: A "file count by ip" limit could be implemented
-  const sasKey = await generateSasKeyForClient(blobClient, inboundIp);
+  const sasKey = await generateSasKeyForClient(
+    blobClient,
+    inboundIp,
+    hoursLimit
+  );
+
   context.log.info(
     `Successfully generated SAS key for file ${filename} and ip ${inboundIp}`
   );

common/index.ts

@@ -1,3 +1,6 @@
+import { env } from "process";
+import type { Context } from "@azure/functions";
+
 /**
  * Use a message
  * @param message
@@ -16,3 +19,19 @@ export function formatReply(
   res.headers = headers;
   return res;
 }
+
+/**
+ * Safely retrieve a var from the environment.
+ * @param varName Name of the env variable
+ * @param fallback Fallback value
+ * @param ctx used to issue a warning when a variable isn't defined
+ * @returns the var value of a fallback
+ */
+export function getEnvVar<T>(varName: string, fallback: T, ctx: Context): T {
+  const envVar = env[varName];
+  if (envVar === undefined) {
+    ctx.log.warn(`${varName} isn't defined ! Defaulting to ${fallback}.`);
+    return fallback;
+  }
+  return envVar as unknown as T;
+}