fix: harden HTTP trust boundaries (#1316)

src/backend/tests/utils/audit-logger.test.ts

@@ -61,7 +61,7 @@ describe("logAudit", () => {
 });
 
 describe("getRequestMeta", () => {
-  it("extracts ip from x-forwarded-for header", () => {
+  it("uses the proxy-validated Express IP", () => {
     const req = {
       headers: {
         "x-forwarded-for": "10.0.0.1, 10.0.0.2",
@@ -71,7 +71,7 @@ describe("getRequestMeta", () => {
       socket: {},
     };
     const meta = getRequestMeta(req as never);
-    expect(meta.ipAddress).toBe("10.0.0.1");
+    expect(meta.ipAddress).toBe("127.0.0.1");
     expect(meta.userAgent).toBe("TestAgent/1.0");
   });
 
@@ -85,16 +85,16 @@ describe("getRequestMeta", () => {
     expect(meta.ipAddress).toBe("192.168.1.1");
   });
 
-  it("splits and trims a forwarded header sent as an array", () => {
+  it("ignores an unvalidated forwarded header", () => {
     const req = {
       headers: {
         "x-forwarded-for": ["10.0.0.1, 10.0.0.2"],
         "user-agent": "TestAgent/1.0",
       },
-      socket: {},
+      socket: { remoteAddress: "203.0.113.9" },
     };
     const meta = getRequestMeta(req as never);
-    expect(meta.ipAddress).toBe("10.0.0.1");
+    expect(meta.ipAddress).toBe("203.0.113.9");
   });
 
   it("falls back to the socket peer when there is no forwarded header or req.ip", () => {

src/backend/tests/utils/audit-username.test.ts

@@ -33,7 +33,7 @@ describe("getAuditUsername", () => {
 });
 
 describe("getRequestMeta", () => {
-  it("prefers the first x-forwarded-for hop", () => {
+  it("prefers the proxy-validated Express IP", () => {
     const meta = getRequestMeta({
       headers: {
         "x-forwarded-for": "203.0.113.9, 10.0.0.1",
@@ -43,7 +43,7 @@ describe("getRequestMeta", () => {
     } as never);
 
     expect(meta).toEqual({
-      ipAddress: "203.0.113.9",
+      ipAddress: "10.0.0.1",
       userAgent: "Mozilla/5.0",
     });
   });

src/backend/tests/utils/cors-config.test.ts

@@ -0,0 +1,48 @@
+import { afterEach, describe, expect, it } from "vitest";
+import type { Request } from "express";
+import { isCorsOriginAllowed } from "../../utils/cors-config.js";
+
+function request(headers: Record<string, string> = {}): Request {
+  return {
+    headers,
+    protocol: "http",
+  } as unknown as Request;
+}
+
+afterEach(() => {
+  delete process.env.CORS_ALLOWED_ORIGINS;
+});
+
+describe("isCorsOriginAllowed", () => {
+  it("allows requests without an Origin header", () => {
+    expect(isCorsOriginAllowed(request(), undefined)).toBe(true);
+  });
+
+  it("allows the externally forwarded same origin", () => {
+    const req = request({
+      "x-forwarded-proto": "https",
+      "x-forwarded-host": "termix.example",
+    });
+    expect(isCorsOriginAllowed(req, "https://termix.example")).toBe(true);
+  });
+
+  it("rejects an unrelated origin even when the TCP peer is loopback", () => {
+    const req = {
+      ...request({ host: "termix.example" }),
+      socket: { remoteAddress: "127.0.0.1" },
+    } as unknown as Request;
+    expect(isCorsOriginAllowed(req, "https://attacker.example")).toBe(false);
+  });
+
+  it("allows an explicitly configured origin", () => {
+    process.env.CORS_ALLOWED_ORIGINS = "https://portal.example";
+    expect(isCorsOriginAllowed(request(), "https://portal.example")).toBe(true);
+  });
+
+  it("does not allow a wildcard with credentialed requests", () => {
+    process.env.CORS_ALLOWED_ORIGINS = "*";
+    expect(isCorsOriginAllowed(request(), "https://attacker.example")).toBe(
+      false,
+    );
+  });
+});

src/backend/tests/utils/request-origin.test.ts

@@ -122,26 +122,27 @@ describe("getRequestBasePath", () => {
 });
 
 describe("getClientIp", () => {
-  it("prefers the leftmost X-Forwarded-For entry over the socket peer", () => {
+  it("uses Express's proxy-validated req.ip", () => {
     expect(
       getClientIp(
         requestWithSocket(
           { "x-forwarded-for": "203.0.113.7, 10.0.0.1, 10.0.0.2" },
           { remoteAddress: "::ffff:127.0.0.1" },
+          "198.51.100.5",
         ),
       ),
-    ).toBe("203.0.113.7");
+    ).toBe("198.51.100.5");
   });
 
-  it("handles X-Forwarded-For sent as a header array", () => {
+  it("does not trust a raw forwarded header without Express validation", () => {
     expect(
       getClientIp(
         requestWithSocket(
-          { "x-forwarded-for": ["203.0.113.7", "10.0.0.1"] },
-          { remoteAddress: "::ffff:127.0.0.1" },
+          { "x-forwarded-for": "127.0.0.1" },
+          { remoteAddress: "198.51.100.9" },
         ),
       ),
-    ).toBe("203.0.113.7");
+    ).toBe("198.51.100.9");
   });
 
   it("falls back to req.ip when there is no forwarded header", () => {