fix(scan): honour the caller context when downloading the ports list (#324)

* fix(scan): honour the caller context when downloading the ports list

the common-scope ports fetch built its request with context.TODO(),
so a cancelled run or -max-time deadline could not abort a hung list
download even though the dialer already used the passed context.

* test(scan): drop redundant comment restating release channel receive

internal/scan/ports.go

@@ -47,7 +47,7 @@ func Ports(ctx context.Context, scope string, url string, timeout time.Duration,
 	var ports []int
 	switch scope {
 	case "common":
-		req, err := http.NewRequestWithContext(context.TODO(), http.MethodGet, commonPorts, http.NoBody)
+		req, err := http.NewRequestWithContext(ctx, http.MethodGet, commonPorts, http.NoBody)
 		if err != nil {
 			log.Error("Error creating request: %s", err)
 			return nil, err

internal/scan/ports_test.go

@@ -0,0 +1,62 @@
+/*
+·━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━·
+:                                                                               :
+:   █▀ █ █▀▀   ·   Blazing-fast pentesting suite                                :
+:   ▄█ █ █▀    ·   BSD 3-Clause License                                         :
+:                                                                               :
+:   (c) 2022-2026 vmfunc, xyzeva,                                               :
+:                 lunchcat alumni & contributors                                :
+:                                                                               :
+·━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━·
+*/
+
+package scan
+
+import (
+	"context"
+	"net/http"
+	"net/http/httptest"
+	"testing"
+	"time"
+)
+
+// TestPorts_CancelledContextAbortsListDownload proves the ports-list fetch
+// honours the caller context. With a slow list endpoint and an already
+// cancelled context, Ports must return promptly instead of blocking on the
+// http client timeout.
+func TestPorts_CancelledContextAbortsListDownload(t *testing.T) {
+	release := make(chan struct{})
+
+	list := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, _ *http.Request) {
+		<-release
+		w.WriteHeader(http.StatusOK)
+	}))
+	// cleanups run LIFO: release the handler first so any in-flight request can
+	// drain before Close waits on it, otherwise a request the ctx failed to
+	// cancel would deadlock teardown.
+	t.Cleanup(list.Close)
+	t.Cleanup(func() { close(release) })
+
+	orig := commonPorts
+	commonPorts = list.URL
+	defer func() { commonPorts = orig }()
+
+	ctx, cancel := context.WithCancel(context.Background())
+	cancel() // cancel before the call so only ctx-awareness can unblock it
+
+	done := make(chan error, 1)
+	go func() {
+		// a generous client timeout so anything but ctx cancellation would hang
+		_, err := Ports(ctx, "common", "tcp://127.0.0.1", 30*time.Second, 1, "")
+		done <- err
+	}()
+
+	select {
+	case err := <-done:
+		if err == nil {
+			t.Fatal("expected error from cancelled context, got nil")
+		}
+	case <-time.After(3 * time.Second):
+		t.Fatal("Ports ignored the cancelled context and blocked on the list download")
+	}
+}