Merge PR #1542 into 2.0.0-beta.2

cmd/gopeed/flags.go

@@ -7,9 +7,11 @@ import (
 )
 
 type args struct {
-	url         string
-	connections *int
-	dir         *string
+	url          string
+	connections  *int
+	dir          *string
+	checksum     *string
+	checksumAlgo *string
 }
 
 func parse() *args {
@@ -20,6 +22,8 @@ func parse() *args {
 	var args args
 	args.connections = flag.Int("C", 16, "Concurrent connections.")
 	args.dir = flag.String("D", dir, "Store directory.")
+	args.checksum = flag.String("checksum", "", "Expected checksum hash (hex encoded).")
+	args.checksumAlgo = flag.String("checksum-algo", "md5", "Checksum algorithm: md5, sha1, or sha256.")
 	flag.Parse()
 	t := flag.Args()
 	if len(t) > 0 {

cmd/gopeed/main.go

@@ -19,6 +19,18 @@ func main() {
 
 	var wg sync.WaitGroup
 	wg.Add(1)
+	var checksumOpt *http.ChecksumOption
+	if args.checksum != nil && *args.checksum != "" {
+		algo := "md5"
+		if args.checksumAlgo != nil && *args.checksumAlgo != "" {
+			algo = *args.checksumAlgo
+		}
+		checksumOpt = &http.ChecksumOption{
+			Algorithm: algo,
+			Expected:  *args.checksum,
+		}
+	}
+
 	_, err := download.Boot().
 		URL(args.url).
 		Listener(func(event *download.Event) {
@@ -43,8 +55,11 @@ func main() {
 			}
 		}).
 		Create(&base.Options{
-			Path:  *args.dir,
-			Extra: http.OptsExtra{Connections: *args.connections},
+			Path: *args.dir,
+			Extra: http.OptsExtra{
+				Connections: *args.connections,
+				Checksum:    checksumOpt,
+			},
 		})
 	if err != nil {
 		panic(err)

internal/protocol/http/fetcher.go

@@ -2,8 +2,13 @@ package http
 
 import (
 	"context"
+	"crypto/md5"
+	"crypto/sha1"
+	"crypto/sha256"
+	"encoding/hex"
 	"errors"
 	"fmt"
+	"hash"
 	"io"
 	"net/http"
 	"net/url"
@@ -280,6 +285,12 @@ type Fetcher struct {
 	primaryReadyOnce sync.Once
 	primaryReadyCh   chan struct{}
 
+	// checksumFailed marks that the last completed download failed
+	// checksum verification, so the next retry must force a full
+	// re-download instead of skipping connections that already
+	// reported Completed.
+	checksumFailed atomic.Bool
+
 	// Start pending mechanism
 	startPending   atomic.Bool
 	resolvedCh     chan struct{} // Signal when resolve completes
@@ -735,12 +746,26 @@ func (f *Fetcher) doStart() error {
 
 	// If retrying after error, reset connection states for retry
 	if state == stateError {
+		forceFullReset := f.checksumFailed.Swap(false)
+		if forceFullReset {
+			// Checksum mismatch: the file content itself is wrong even
+			// though every connection reported Completed. Truncate the
+			// corrupt file so stale bytes cannot linger if the retry is
+			// interrupted before every connection re-writes its chunk.
+			if err := os.Truncate(f.meta.SingleFilepath(), 0); err != nil && !os.IsNotExist(err) {
+				return fmt.Errorf("failed to reset file after checksum mismatch: %w", err)
+			}
+		}
 		f.connMu.Lock()
 		for _, conn := range f.connections {
-			// Reset connections that can be retried
-			if !conn.Completed && conn.State != connCompleted {
+			// On a normal error, only reset connections that didn't
+			// finish. On a checksum mismatch, reset EVERY connection —
+			// "Completed" only means the download loop finished, not
+			// that the bytes were verified correct.
+			shouldReset := forceFullReset || (!conn.Completed && conn.State != connCompleted)
+			if shouldReset {
 				if !f.hasSequentialPrefixLocked(conn) {
-					f.resetConnectionForRestart(conn)
+					f.resetConnectionForRestart(conn, forceFullReset)
 				}
 				conn.State = connNotStarted
 				conn.failed = false
@@ -970,8 +995,14 @@ func (f *Fetcher) expandConnections() {
 			}
 			f.fileMu.Unlock()
 
-			f.setState(stateDone)
-			f.doneCh <- nil
+			var err error
+			if chkErr := f.verifyChecksum(); chkErr != nil {
+				err = chkErr
+				f.setState(stateError)
+			} else {
+				f.setState(stateDone)
+			}
+			f.doneCh <- err
 			return
 		}
 
@@ -1107,7 +1138,7 @@ func (f *Fetcher) runConnection(conn *connection) {
 			// it only when no safe validator exists or If-Range returns a full 200.
 			f.connMu.Lock()
 			if !f.hasSequentialPrefixLocked(conn) {
-				f.resetConnectionForRestart(conn)
+				f.resetConnectionForRestart(conn, false)
 			}
 			f.connMu.Unlock()
 		}
@@ -1214,7 +1245,7 @@ func (f *Fetcher) downloadChunkOnce(conn *connection, client *http.Client, buf [
 	resumeProbe := f.canProbeSequentialResumeLocked(conn)
 	intentionalRestart := sequentialSizeUnknown
 	if sequentialSizeUnknown || (hasSequentialPrefix && !resumeProbe) {
-		f.resetConnectionForRestart(conn)
+		f.resetConnectionForRestart(conn, false)
 		f.resolveDataPos.Store(0)
 		f.rangeValidatorPinned = false
 		intentionalRestart = true
@@ -1659,7 +1690,7 @@ func (f *Fetcher) fallbackToSequentialDownload(conn *connection, ifRange string)
 	f.rangeReprobeEligible = true
 	f.rangeValidatorPinned = false
 	f.ifRange = ifRange
-	f.resetConnectionForRestart(conn)
+	f.resetConnectionForRestart(conn, false)
 	f.resolveDataPos.Store(0)
 	return nil
 }
@@ -1675,7 +1706,7 @@ func (f *Fetcher) restartSequentialDownload(conn *connection, ifRange string) {
 	f.rangeReprobeEligible = true
 	f.rangeValidatorPinned = false
 	f.ifRange = ifRange
-	f.resetConnectionForRestart(conn)
+	f.resetConnectionForRestart(conn, false)
 	f.resolveDataPos.Store(0)
 }
 
@@ -2058,16 +2089,25 @@ func (f *Fetcher) helpOtherConnection(helper *connection) bool {
 	return true
 }
 
-func (f *Fetcher) resetConnectionForRestart(conn *connection) {
-	if f.meta.Res.Range {
+func (f *Fetcher) resetConnectionForRestart(conn *connection, force bool) {
+	if f.meta.Res.Range && !force {
 		return
 	}
+	if f.meta.Res.Range && force {
+		// Checksum mismatch: the on-disk content for this chunk is
+		// confirmed wrong, so its bytes must be re-fetched from the
+		// origin server even though range support would normally let
+		// us just resume from the existing Downloaded position.
+		if conn.Chunk != nil {
+			conn.Chunk.Downloaded = 0
+		}
+	}
 
 	// Without range support a new request always starts from byte 0,
 	// so pause/retry must restart instead of continuing from the old offset.
 	if conn.Chunk == nil {
 		conn.Chunk = newChunk(0, 0)
-	} else {
+	} else if !f.meta.Res.Range {
 		conn.Chunk.Begin = 0
 		conn.Chunk.setEnd(0)
 		conn.Chunk.Downloaded = 0
@@ -2131,7 +2171,7 @@ func (f *Fetcher) resumeConnections() {
 			}
 		}
 		if !f.hasSequentialPrefixLocked(conn) {
-			f.resetConnectionForRestart(conn)
+			f.resetConnectionForRestart(conn, false)
 		}
 		// Reset the connection state for resume
 		conn.ctx, conn.cancel = context.WithCancel(f.ctx)
@@ -2238,10 +2278,15 @@ func (f *Fetcher) onDownloadComplete() {
 	}
 	f.fileMu.Unlock()
 
-	if finalErr != nil {
-		f.setState(stateError)
+	if finalErr == nil {
+		if chkErr := f.verifyChecksum(); chkErr != nil {
+			finalErr = chkErr
+			f.setState(stateError)
+		} else {
+			f.setState(stateDone)
+		}
 	} else {
-		f.setState(stateDone)
+		f.setState(stateError)
 	}
 
 	select {
@@ -2250,6 +2295,51 @@ func (f *Fetcher) onDownloadComplete() {
 	}
 }
 
+func (f *Fetcher) verifyChecksum() error {
+	if f.meta == nil || f.meta.Opts == nil || f.meta.Opts.Extra == nil {
+		return nil
+	}
+	extra, ok := f.meta.Opts.Extra.(*fhttp.OptsExtra)
+	if !ok || extra.Checksum == nil {
+		return nil
+	}
+	chk := extra.Checksum
+	if chk.Algorithm == "" && chk.Expected == "" {
+		return nil
+	}
+	var h hash.Hash
+	switch strings.ToLower(strings.TrimSpace(chk.Algorithm)) {
+	case "md5":
+		h = md5.New()
+	case "sha1", "sha-1":
+		h = sha1.New()
+	case "sha256", "sha-256":
+		h = sha256.New()
+	default:
+		return fmt.Errorf("unsupported checksum algorithm: %s", chk.Algorithm)
+	}
+
+	filePath := f.meta.SingleFilepath()
+	file, err := os.Open(filePath)
+	if err != nil {
+		return fmt.Errorf("open file for checksum verification failed: %w", err)
+	}
+	defer file.Close()
+
+	buf := make([]byte, 64*1024)
+	if _, err := io.CopyBuffer(h, file, buf); err != nil {
+		return fmt.Errorf("calculate checksum failed: %w", err)
+	}
+
+	actual := hex.EncodeToString(h.Sum(nil))
+	expected := strings.ToLower(strings.TrimSpace(chk.Expected))
+	if !strings.EqualFold(actual, expected) {
+		f.checksumFailed.Store(true)
+		return fmt.Errorf("checksum mismatch: expected %s, got %s", expected, actual)
+	}
+	return nil
+}
+
 func (f *Fetcher) checkCompletion() bool {
 	// Check if all data has been downloaded
 	f.connMu.Lock()

internal/protocol/http/fetcher_checksum_retry_test.go

@@ -0,0 +1,108 @@
+package http
+
+import (
+	"crypto/sha256"
+	"encoding/hex"
+	"fmt"
+	gohttp "net/http"
+	"net/http/httptest"
+	"os"
+	"strings"
+	"sync/atomic"
+	"testing"
+
+	"github.com/GopeedLab/gopeed/pkg/base"
+	"github.com/GopeedLab/gopeed/pkg/protocol/http"
+)
+
+func TestFetcher_ChecksumMismatch_Retry(t *testing.T) {
+	corruptContent := []byte("Corrupt Initial Download Data!")
+	correctContent := []byte("Correct Retried Download Data!")
+
+	correctSha256Hasher := sha256.New()
+	correctSha256Hasher.Write(correctContent)
+	correctSha256 := hex.EncodeToString(correctSha256Hasher.Sum(nil))
+
+	var reqCount atomic.Int32
+	server := httptest.NewServer(gohttp.HandlerFunc(func(w gohttp.ResponseWriter, r *gohttp.Request) {
+		count := reqCount.Add(1)
+		var served []byte
+		if count == 1 {
+			// First request: serve corrupted content
+			served = corruptContent
+		} else {
+			// Second / subsequent request: serve correct content
+			served = correctContent
+		}
+		w.Header().Set(base.HttpHeaderContentLength, fmt.Sprintf("%d", len(served)))
+		w.Header().Set(base.HttpHeaderAcceptRanges, base.HttpHeaderBytes)
+		w.WriteHeader(gohttp.StatusOK)
+		_, _ = w.Write(served)
+	}))
+	defer server.Close()
+
+	downloadDir := t.TempDir()
+	fileName := "test_checksum_retry.txt"
+
+	f := buildFetcher()
+	defer f.Close()
+
+	opts := &base.Options{
+		Path: downloadDir,
+		Name: fileName,
+		Extra: &http.OptsExtra{
+			Connections: 1,
+			Checksum: &http.ChecksumOption{
+				Algorithm: "sha256",
+				Expected:  correctSha256,
+			},
+		},
+	}
+
+	// 1. Initial attempt -> will download corruptContent, failing checksum verification
+	if err := f.Resolve(&base.Request{URL: server.URL + "/retry_test.txt"}, opts); err != nil {
+		t.Fatalf("Resolve error: %v", err)
+	}
+	if err := f.Start(); err != nil {
+		t.Fatalf("Start error: %v", err)
+	}
+	err := f.Wait()
+	if err == nil {
+		t.Fatal("expected checksum mismatch error on initial attempt, got nil")
+	}
+	if !strings.Contains(err.Error(), "checksum mismatch") {
+		t.Fatalf("expected 'checksum mismatch' in error, got %v", err)
+	}
+	if f.getState() != stateError {
+		t.Fatalf("expected stateError after checksum mismatch, got %v", f.getState())
+	}
+
+	// 2. Retry download -> should trigger forced full reset, truncate file, and re-download correctContent
+	if err := f.Start(); err != nil {
+		t.Fatalf("Start error on retry: %v", err)
+	}
+	if err := f.Wait(); err != nil {
+		t.Fatalf("Wait error on retry (expected success): %v", err)
+	}
+	if f.getState() != stateDone {
+		t.Fatalf("expected stateDone after successful retry, got %v", f.getState())
+	}
+
+	// 3. Verify on-disk file content matches the re-downloaded bytes
+	filePath := f.meta.SingleFilepath()
+	fileBytes, err := os.ReadFile(filePath)
+	if err != nil {
+		t.Fatalf("failed to read completed file: %v", err)
+	}
+	if string(fileBytes) != string(correctContent) {
+		t.Fatalf("on-disk file content mismatch:\ngot:  %q\nwant: %q", string(fileBytes), string(correctContent))
+	}
+
+	// 4. Compute hash independently and verify
+	actualHasher := sha256.New()
+	actualHasher.Write(fileBytes)
+	actualHash := hex.EncodeToString(actualHasher.Sum(nil))
+	if actualHash != correctSha256 {
+		t.Fatalf("re-computed on-disk hash mismatch: got %s, want %s", actualHash, correctSha256)
+	}
+}

internal/protocol/http/fetcher_checksum_test.go

@@ -0,0 +1,307 @@
+package http
+
+import (
+	"crypto/md5"
+	"crypto/sha256"
+	"encoding/hex"
+	"fmt"
+	gohttp "net/http"
+	"net/http/httptest"
+	"strings"
+	"testing"
+
+	"github.com/GopeedLab/gopeed/internal/fetcher"
+	"github.com/GopeedLab/gopeed/internal/test"
+	"github.com/GopeedLab/gopeed/pkg/base"
+	"github.com/GopeedLab/gopeed/pkg/protocol/http"
+)
+
+func TestFetcher_ChecksumVerification(t *testing.T) {
+	content := []byte("Hello, Gopeed Checksum Verification Test Data!")
+	md5Hasher := md5.New()
+	md5Hasher.Write(content)
+	correctMd5 := hex.EncodeToString(md5Hasher.Sum(nil))
+
+	sha256Hasher := sha256.New()
+	sha256Hasher.Write(content)
+	correctSha256 := hex.EncodeToString(sha256Hasher.Sum(nil))
+
+	wrongHash := "0123456789abcdef0123456789abcdef"
+
+	server := httptest.NewServer(gohttp.HandlerFunc(func(w gohttp.ResponseWriter, r *gohttp.Request) {
+		w.Header().Set(base.HttpHeaderContentLength, fmt.Sprintf("%d", len(content)))
+		w.Header().Set(base.HttpHeaderAcceptRanges, base.HttpHeaderBytes)
+		w.WriteHeader(gohttp.StatusOK)
+		_, _ = w.Write(content)
+	}))
+	defer server.Close()
+
+	t.Run("Valid MD5", func(t *testing.T) {
+		f := buildFetcher()
+		defer f.Close()
+
+		opts := &base.Options{
+			Path: t.TempDir(),
+			Name: "test_valid_md5.txt",
+			Extra: &http.OptsExtra{
+				Connections: 1,
+				Checksum: &http.ChecksumOption{
+					Algorithm: "md5",
+					Expected:  correctMd5,
+				},
+			},
+		}
+
+		if err := f.Resolve(&base.Request{URL: server.URL + "/test.txt"}, opts); err != nil {
+			t.Fatalf("Resolve error: %v", err)
+		}
+		if err := f.Start(); err != nil {
+			t.Fatalf("Start error: %v", err)
+		}
+		if err := f.Wait(); err != nil {
+			t.Fatalf("Wait error (expected success): %v", err)
+		}
+	})
+
+	t.Run("Valid SHA256", func(t *testing.T) {
+		f := buildFetcher()
+		defer f.Close()
+
+		opts := &base.Options{
+			Path: t.TempDir(),
+			Name: "test_valid_sha256.txt",
+			Extra: &http.OptsExtra{
+				Connections: 1,
+				Checksum: &http.ChecksumOption{
+					Algorithm: "sha256",
+					Expected:  correctSha256,
+				},
+			},
+		}
+
+		if err := f.Resolve(&base.Request{URL: server.URL + "/test.txt"}, opts); err != nil {
+			t.Fatalf("Resolve error: %v", err)
+		}
+		if err := f.Start(); err != nil {
+			t.Fatalf("Start error: %v", err)
+		}
+		if err := f.Wait(); err != nil {
+			t.Fatalf("Wait error (expected success): %v", err)
+		}
+	})
+
+	t.Run("Wrong MD5 mismatch", func(t *testing.T) {
+		f := buildFetcher()
+		defer f.Close()
+
+		opts := &base.Options{
+			Path: t.TempDir(),
+			Name: "test_wrong_md5.txt",
+			Extra: &http.OptsExtra{
+				Connections: 1,
+				Checksum: &http.ChecksumOption{
+					Algorithm: "md5",
+					Expected:  wrongHash,
+				},
+			},
+		}
+
+		if err := f.Resolve(&base.Request{URL: server.URL + "/test.txt"}, opts); err != nil {
+			t.Fatalf("Resolve error: %v", err)
+		}
+		if err := f.Start(); err != nil {
+			t.Fatalf("Start error: %v", err)
+		}
+		err := f.Wait()
+		if err == nil {
+			t.Fatal("Wait expected checksum mismatch error, got nil")
+		}
+		if !strings.Contains(err.Error(), "checksum mismatch") {
+			t.Fatalf("expected 'checksum mismatch' in error, got %v", err)
+		}
+	})
+
+	t.Run("Unsupported Algorithm", func(t *testing.T) {
+		f := buildFetcher()
+		defer f.Close()
+
+		opts := &base.Options{
+			Path: t.TempDir(),
+			Name: "test_unsupported.txt",
+			Extra: &http.OptsExtra{
+				Connections: 1,
+				Checksum: &http.ChecksumOption{
+					Algorithm: "invalid-algo",
+					Expected:  wrongHash,
+				},
+			},
+		}
+
+		if err := f.Resolve(&base.Request{URL: server.URL + "/test.txt"}, opts); err != nil {
+			t.Fatalf("Resolve error: %v", err)
+		}
+		if err := f.Start(); err != nil {
+			t.Fatalf("Start error: %v", err)
+		}
+		err := f.Wait()
+		if err == nil {
+			t.Fatal("Wait expected error for unsupported algorithm, got nil")
+		}
+		if !strings.Contains(err.Error(), "unsupported checksum algorithm") {
+			t.Fatalf("expected 'unsupported checksum algorithm' in error, got %v", err)
+		}
+		if f.checksumFailed.Load() {
+			t.Fatal("checksumFailed flag should NOT be set on unsupported algorithm error")
+		}
+	})
+
+	t.Run("Case-Insensitive Hash Comparison", func(t *testing.T) {
+		f := buildFetcher()
+		defer f.Close()
+
+		opts := &base.Options{
+			Path: t.TempDir(),
+			Name: "test_case_insensitive.txt",
+			Extra: &http.OptsExtra{
+				Connections: 1,
+				Checksum: &http.ChecksumOption{
+					Algorithm: "sha256",
+					Expected:  strings.ToUpper(correctSha256),
+				},
+			},
+		}
+
+		if err := f.Resolve(&base.Request{URL: server.URL + "/test.txt"}, opts); err != nil {
+			t.Fatalf("Resolve error: %v", err)
+		}
+		if err := f.Start(); err != nil {
+			t.Fatalf("Start error: %v", err)
+		}
+		if err := f.Wait(); err != nil {
+			t.Fatalf("Wait error (expected success with upper case hash): %v", err)
+		}
+	})
+
+	t.Run("Empty Expected Checksum (Skipped)", func(t *testing.T) {
+		f := buildFetcher()
+		defer f.Close()
+
+		opts := &base.Options{
+			Path: t.TempDir(),
+			Name: "test_empty_expected.txt",
+			Extra: &http.OptsExtra{
+				Connections: 1,
+				Checksum: &http.ChecksumOption{
+					Algorithm: "",
+					Expected:  "",
+				},
+			},
+		}
+
+		if err := f.Resolve(&base.Request{URL: server.URL + "/test.txt"}, opts); err != nil {
+			t.Fatalf("Resolve error: %v", err)
+		}
+		if err := f.Start(); err != nil {
+			t.Fatalf("Start error: %v", err)
+		}
+		if err := f.Wait(); err != nil {
+			t.Fatalf("Wait error (expected skip and success): %v", err)
+		}
+	})
+
+	t.Run("Large File Multi-Chunk Streaming (>64KB)", func(t *testing.T) {
+		largeData := make([]byte, 128*1024)
+		for i := range largeData {
+			largeData[i] = byte(i % 256)
+		}
+		largeSha256Hasher := sha256.New()
+		largeSha256Hasher.Write(largeData)
+		largeSha256 := hex.EncodeToString(largeSha256Hasher.Sum(nil))
+
+		largeServer := httptest.NewServer(gohttp.HandlerFunc(func(w gohttp.ResponseWriter, r *gohttp.Request) {
+			w.Header().Set(base.HttpHeaderContentLength, fmt.Sprintf("%d", len(largeData)))
+			w.Header().Set(base.HttpHeaderAcceptRanges, base.HttpHeaderBytes)
+			w.WriteHeader(gohttp.StatusOK)
+			_, _ = w.Write(largeData)
+		}))
+		defer largeServer.Close()
+
+		f := buildFetcher()
+		defer f.Close()
+
+		opts := &base.Options{
+			Path: t.TempDir(),
+			Name: "test_large_file.bin",
+			Extra: &http.OptsExtra{
+				Connections: 1,
+				Checksum: &http.ChecksumOption{
+					Algorithm: "sha256",
+					Expected:  largeSha256,
+				},
+			},
+		}
+
+		if err := f.Resolve(&base.Request{URL: largeServer.URL + "/large.bin"}, opts); err != nil {
+			t.Fatalf("Resolve error: %v", err)
+		}
+		if err := f.Start(); err != nil {
+			t.Fatalf("Start error: %v", err)
+		}
+		if err := f.Wait(); err != nil {
+			t.Fatalf("Wait error (expected large file checksum success): %v", err)
+		}
+	})
+
+	t.Run("No Checksum (Opt-in backward compatibility)", func(t *testing.T) {
+		f := buildFetcher()
+		defer f.Close()
+
+		opts := &base.Options{
+			Path: t.TempDir(),
+			Name: test.DownloadName,
+			Extra: &http.OptsExtra{
+				Connections: 1,
+			},
+		}
+
+		if err := f.Resolve(&base.Request{URL: server.URL + "/test.txt"}, opts); err != nil {
+			t.Fatalf("Resolve error: %v", err)
+		}
+		if err := f.Start(); err != nil {
+			t.Fatalf("Start error: %v", err)
+		}
+		if err := f.Wait(); err != nil {
+			t.Fatalf("Wait error: %v", err)
+		}
+	})
+}
+
+func TestResetConnectionForRestart_ForceOnRangeDownload(t *testing.T) {
+	f := buildFetcher()
+	f.meta = &fetcher.FetcherMeta{
+		Res: &base.Resource{
+			Range: true,
+		},
+	}
+	conn := &connection{
+		Chunk:      newChunk(0, 1024),
+		Downloaded: 512,
+		Completed:  true,
+	}
+	conn.Chunk.Downloaded = 512
+
+	// Non-forced reset on range-supported download does not reset Chunk.Downloaded
+	f.resetConnectionForRestart(conn, false)
+	if conn.Chunk.Downloaded != 512 {
+		t.Fatalf("expected Chunk.Downloaded to remain 512 when force is false, got %d", conn.Chunk.Downloaded)
+	}
+
+	// Forced reset on range-supported download resets Chunk.Downloaded to 0
+	f.resetConnectionForRestart(conn, true)
+	if conn.Chunk.Downloaded != 0 {
+		t.Fatalf("expected Chunk.Downloaded to be reset to 0 when force is true, got %d", conn.Chunk.Downloaded)
+	}
+	if conn.Completed {
+		t.Fatal("expected Completed to be false after reset")
+	}
+}

pkg/download/downloader.go

@@ -1912,6 +1912,7 @@ func (d *Downloader) doPause(task *Task) (err error) {
 	}
 	if handled {
 		d.emit(EventKeyPause, task)
+		d.triggerWebhooks(WebhookEventDownloadPause, task, nil)
 	}
 	return nil
 }

pkg/download/model.go

@@ -23,6 +23,9 @@ type ResolveResult struct {
 	Res *base.Resource `json:"res"`
 }
 
+// Task represents a download unit.
+// Options flow path:
+// REST Request (model.CreateTask/ResolveTask) -> pkg/download Downloader -> Task.Meta.Opts (base.Options) -> Fetcher.Resolve/Start (e.g. internal/protocol/http/fetcher.go)
 type Task struct {
 	ID        string               `json:"id"`
 	Protocol  string               `json:"protocol"`

pkg/download/webhook.go

@@ -21,6 +21,7 @@ type WebhookEvent string
 const (
 	WebhookEventDownloadDone  WebhookEvent = "DOWNLOAD_DONE"
 	WebhookEventDownloadError WebhookEvent = "DOWNLOAD_ERROR"
+	WebhookEventDownloadPause WebhookEvent = "DOWNLOAD_PAUSE"
 )
 
 // WebhookData is the data sent to webhook URLs

pkg/download/webhook_test.go

@@ -814,6 +814,49 @@ func TestWebhook_TestWebhookUrl_VerifyTestPayload(t *testing.T) {
 	})
 }
 
+func TestWebhook_TriggerOnPause(t *testing.T) {
+	receivedData := make(chan *WebhookData, 1)
+	server := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		var data WebhookData
+		if err := json.NewDecoder(r.Body).Decode(&data); err != nil {
+			t.Errorf("Failed to decode data: %v", err)
+			return
+		}
+		receivedData <- &data
+		w.WriteHeader(http.StatusOK)
+	}))
+	defer server.Close()
+
+	setupWebhookTest(t, func(downloader *Downloader) {
+		cfg, _ := downloader.GetConfig()
+		cfg.Webhook = &base.WebhookConfig{
+			Enable: true,
+			URLs:   []string{server.URL},
+		}
+		downloader.PutConfig(cfg)
+
+		task := NewTask()
+		task.Protocol = "http"
+		task.Meta = &mockFetcherMeta
+
+		downloader.triggerWebhooks(WebhookEventDownloadPause, task, nil)
+
+		select {
+		case data := <-receivedData:
+			if data.Event != WebhookEventDownloadPause {
+				t.Errorf("Expected event 'DOWNLOAD_PAUSE', got '%s'", data.Event)
+			}
+			if data.Payload == nil || data.Payload.Task == nil {
+				t.Error("Expected payload.task to be present")
+			} else if data.Payload.Task.ID != task.ID {
+				t.Errorf("Expected task ID '%s', got '%s'", task.ID, data.Payload.Task.ID)
+			}
+		case <-time.After(2 * time.Second):
+			t.Error("Timeout waiting for webhook")
+		}
+	})
+}
+
 func setupWebhookTest(t *testing.T, fn func(downloader *Downloader)) {
 	defaultDownloader.Setup()
 	defaultDownloader.cfg.StorageDir = ".test_storage"

pkg/mcpserver/server.go

@@ -12,6 +12,7 @@ import (
 
 	"github.com/GopeedLab/gopeed/pkg/base"
 	"github.com/GopeedLab/gopeed/pkg/download"
+	phttp "github.com/GopeedLab/gopeed/pkg/protocol/http"
 	"github.com/google/jsonschema-go/jsonschema"
 	"github.com/modelcontextprotocol/go-sdk/mcp"
 )
@@ -65,12 +66,13 @@ type btRequestExtra struct {
 }
 
 type httpTaskExtra struct {
-	Connections                int    `json:"connections,omitempty" jsonschema:"Number of HTTP download connections"`
-	AutoTorrent                *bool  `json:"autoTorrent,omitempty" jsonschema:"Automatically create a BitTorrent task after downloading a torrent file"`
-	DeleteTorrentAfterDownload *bool  `json:"deleteTorrentAfterDownload,omitempty" jsonschema:"Delete the torrent file after automatically creating its BitTorrent task"`
-	AutoExtract                *bool  `json:"autoExtract,omitempty" jsonschema:"Automatically extract the downloaded archive"`
-	ArchivePassword            string `json:"archivePassword,omitempty" jsonschema:"Password for an encrypted archive"`
-	DeleteAfterExtract         bool   `json:"deleteAfterExtract,omitempty" jsonschema:"Delete archive files after successful extraction"`
+	Connections                int             `json:"connections,omitempty" jsonschema:"Number of HTTP download connections"`
+	AutoTorrent                *bool           `json:"autoTorrent,omitempty" jsonschema:"Automatically create a BitTorrent task after downloading a torrent file"`
+	DeleteTorrentAfterDownload *bool           `json:"deleteTorrentAfterDownload,omitempty" jsonschema:"Delete the torrent file after automatically creating its BitTorrent task"`
+	AutoExtract                *bool           `json:"autoExtract,omitempty" jsonschema:"Automatically extract the downloaded archive"`
+	ArchivePassword            string          `json:"archivePassword,omitempty" jsonschema:"Password for an encrypted archive"`
+	DeleteAfterExtract         bool            `json:"deleteAfterExtract,omitempty" jsonschema:"Delete archive files after successful extraction"`
+	Checksum                   *checksumOption `json:"checksum,omitempty" jsonschema:"Optional checksum verification settings"`
 }
 
 // downloadRequest is the MCP-facing form of base.Request. The REST model uses
@@ -129,6 +131,11 @@ func isBitTorrentRequest(rawURL string) bool {
 		strings.HasPrefix(upperURL, "DATA:APPLICATION/X-BITTORRENT;BASE64,")
 }
 
+type checksumOption struct {
+	Algorithm string `json:"algorithm" jsonschema:"Checksum algorithm: md5, sha1, or sha256"`
+	Expected  string `json:"expected" jsonschema:"Expected hex-encoded checksum hash"`
+}
+
 // downloadOptions is the MCP-facing form of base.Options. Only HTTP currently
 // defines protocol-specific task options, so Extra has one concrete schema.
 type downloadOptions struct {
@@ -186,12 +193,31 @@ func (o *downloadOptions) baseOptions() *base.Options {
 	if o == nil {
 		return nil
 	}
+	var extra any
+	if o.Extra != nil {
+		var checksum *phttp.ChecksumOption
+		if o.Extra.Checksum != nil {
+			checksum = &phttp.ChecksumOption{
+				Algorithm: o.Extra.Checksum.Algorithm,
+				Expected:  o.Extra.Checksum.Expected,
+			}
+		}
+		extra = &phttp.OptsExtra{
+			Connections:                o.Extra.Connections,
+			AutoTorrent:                o.Extra.AutoTorrent,
+			DeleteTorrentAfterDownload: o.Extra.DeleteTorrentAfterDownload,
+			AutoExtract:                o.Extra.AutoExtract,
+			ArchivePassword:            o.Extra.ArchivePassword,
+			DeleteAfterExtract:         o.Extra.DeleteAfterExtract,
+			Checksum:                   checksum,
+		}
+	}
 	return &base.Options{
 		Name:          o.Name,
 		Path:          o.Path,
 		AsDefaultPath: o.AsDefaultPath,
 		SelectFiles:   o.SelectFiles,
-		Extra:         o.Extra,
+		Extra:         extra,
 	}
 }
 
@@ -270,6 +296,13 @@ type getTaskStatsOutput struct {
 	Stats any `json:"stats"`
 }
 
+type getDownloadSpeedInput struct{}
+
+type getDownloadSpeedOutput struct {
+	TotalSpeed      int64 `json:"totalSpeed"`
+	ActiveTaskCount int   `json:"activeTaskCount"`
+}
+
 type taskActionOutput struct {
 	ID      string `json:"id"`
 	Success bool   `json:"success"`
@@ -416,6 +449,33 @@ func registerTools(server *mcp.Server, downloader *download.Downloader) {
 		return nil, &getTaskStatsOutput{Stats: stats}, nil
 	})
 
+	mcp.AddTool(server, &mcp.Tool{
+		Name:        "get_download_speed",
+		Title:       "Get download speed",
+		Description: "Returns the combined download speed across all currently active tasks and how many tasks are actively downloading. Use get_task_status instead if you need the speed, progress, or ETA of one specific task.",
+		Annotations: &mcp.ToolAnnotations{ReadOnlyHint: true, OpenWorldHint: &closedWorld},
+	}, func(_ context.Context, _ *mcp.CallToolRequest, _ *getDownloadSpeedInput) (*mcp.CallToolResult, *getDownloadSpeedOutput, error) {
+		allTasks := downloader.GetTasks()
+		var totalSpeed int64
+		activeCount := 0
+
+		for _, task := range allTasks {
+			status, err := downloader.RuntimeStatus(task.ID)
+			if err != nil {
+				continue
+			}
+			if status.Status == base.DownloadStatusRunning {
+				activeCount++
+				totalSpeed += status.Speed
+			}
+		}
+
+		return nil, &getDownloadSpeedOutput{
+			TotalSpeed:      totalSpeed,
+			ActiveTaskCount: activeCount,
+		}, nil
+	})
+
 	registerTaskAction(server, downloader, "pause_task", "Pause task", "Pause one Gopeed task.", &nondestructive, &closedWorld, downloader.Pause)
 	registerTaskAction(server, downloader, "continue_task", "Continue task", "Continue a paused or failed Gopeed task.", &nondestructive, &openWorld, downloader.Continue)
 

pkg/mcpserver/server_test.go

@@ -64,6 +64,7 @@ func TestStreamableHTTPTools(t *testing.T) {
 		"continue_task",
 		"create_task",
 		"delete_task",
+		"get_download_speed",
 		"get_task",
 		"get_task_stats",
 		"get_task_status",

pkg/mcpserver/speed_test.go

@@ -0,0 +1,103 @@
+package mcpserver
+
+import (
+	"context"
+	"net/http"
+	"net/http/httptest"
+	"testing"
+	"time"
+
+	"github.com/GopeedLab/gopeed/pkg/base"
+	"github.com/GopeedLab/gopeed/pkg/download"
+	"github.com/modelcontextprotocol/go-sdk/mcp"
+)
+
+func TestGetDownloadSpeedTool(t *testing.T) {
+	// Serve a test payload that takes a little bit of time or streams bytes
+	testServer := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		w.Header().Set("Content-Length", "1048576")
+		w.WriteHeader(http.StatusOK)
+		chunk := make([]byte, 8192)
+		for i := 0; i < 128; i++ {
+			_, _ = w.Write(chunk)
+			time.Sleep(10 * time.Millisecond)
+		}
+	}))
+	defer testServer.Close()
+
+	downloader := download.NewDownloader(&download.DownloaderConfig{
+		Storage:    download.NewMemStorage(),
+		StorageDir: t.TempDir(),
+	})
+	if err := downloader.Setup(); err != nil {
+		t.Fatal(err)
+	}
+	defer downloader.Close()
+
+	httpServer := httptest.NewServer(NewHandler(downloader))
+	defer httpServer.Close()
+
+	client := mcp.NewClient(&mcp.Implementation{Name: "gopeed-test", Version: "1.0.0"}, nil)
+	session, err := client.Connect(context.Background(), &mcp.StreamableClientTransport{Endpoint: httpServer.URL}, nil)
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer session.Close()
+
+	// 1. Zero tasks test (returns 0 totalSpeed and 0 activeTaskCount)
+	result, err := session.CallTool(context.Background(), &mcp.CallToolParams{
+		Name:      "get_download_speed",
+		Arguments: map[string]any{},
+	})
+	if err != nil {
+		t.Fatal(err)
+	}
+	if result.IsError {
+		t.Fatalf("get_download_speed returned error: %+v", result.Content)
+	}
+	structured, ok := result.StructuredContent.(map[string]any)
+	if !ok {
+		t.Fatalf("structured content type = %T", result.StructuredContent)
+	}
+	if activeCount, ok := structured["activeTaskCount"].(float64); !ok || activeCount != 0 {
+		t.Fatalf("activeTaskCount = %v, want 0", structured["activeTaskCount"])
+	}
+	if totalSpeed, ok := structured["totalSpeed"].(float64); !ok || totalSpeed != 0 {
+		t.Fatalf("totalSpeed = %v, want 0", structured["totalSpeed"])
+	}
+
+	// 2. Start a real download task
+	taskID, err := downloader.CreateDirect(&base.Request{
+		URL: testServer.URL,
+	}, &base.Options{
+		Path: t.TempDir(),
+	})
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer func() {
+		_ = downloader.Delete(&download.TaskFilter{IDs: []string{taskID}}, true)
+	}()
+
+	// Query get_download_speed while downloading
+	result, err = session.CallTool(context.Background(), &mcp.CallToolParams{
+		Name:      "get_download_speed",
+		Arguments: map[string]any{},
+	})
+	if err != nil {
+		t.Fatal(err)
+	}
+	if result.IsError {
+		t.Fatalf("get_download_speed returned error: %+v", result.Content)
+	}
+	structured, ok = result.StructuredContent.(map[string]any)
+	if !ok {
+		t.Fatalf("structured content type = %T", result.StructuredContent)
+	}
+	if _, ok := structured["activeTaskCount"].(float64); !ok {
+		t.Fatalf("activeTaskCount missing or wrong type: %v", structured["activeTaskCount"])
+	}
+	if _, ok := structured["totalSpeed"].(float64); !ok {
+		t.Fatalf("totalSpeed missing or wrong type: %v", structured["totalSpeed"])
+	}
+}

pkg/protocol/http/model.go

@@ -6,6 +6,13 @@ type ReqExtra struct {
 	Body   string            `json:"body"`
 }
 
+// ChecksumOption specifies an expected checksum to verify against
+// the completed download. Only supported for HTTP downloads.
+type ChecksumOption struct {
+	Algorithm string `json:"algorithm"` // "md5" | "sha1" | "sha256"
+	Expected  string `json:"expected"`  // hex-encoded expected hash
+}
+
 type OptsExtra struct {
 	Connections int `json:"connections"`
 	// AutoTorrent when task download complete, and it is a .torrent file, it will be auto create a new task for the torrent file
@@ -21,6 +28,8 @@ type OptsExtra struct {
 	ArchivePassword string `json:"archivePassword"`
 	// DeleteAfterExtract when true, deletes the archive file after successful extraction
 	DeleteAfterExtract bool `json:"deleteAfterExtract"`
+	// Checksum verifies the completed file against an expected hash after download
+	Checksum *ChecksumOption `json:"checksum,omitempty"`
 }
 
 // Stats for download

pkg/protocol/http/model_test.go

@@ -0,0 +1,15 @@
+package http
+
+import "testing"
+
+func TestOptsExtra_Checksum(t *testing.T) {
+	extra := &OptsExtra{
+		Checksum: &ChecksumOption{
+			Algorithm: "sha256",
+			Expected:  "abcdef1234567890",
+		},
+	}
+	if extra.Checksum.Algorithm != "sha256" || extra.Checksum.Expected != "abcdef1234567890" {
+		t.Fatalf("unexpected checksum: %+v", extra.Checksum)
+	}
+}

ui/flutter/lib/api/model/options.dart

@@ -17,6 +17,21 @@ class Options {
   Map<String, dynamic> toJson() => _$OptionsToJson(this);
 }
 
+@JsonSerializable()
+class ChecksumOption {
+  String algorithm;
+  String expected;
+
+  ChecksumOption({
+    this.algorithm = '',
+    this.expected = '',
+  });
+
+  factory ChecksumOption.fromJson(Map<String, dynamic> json) => _$ChecksumOptionFromJson(json);
+
+  Map<String, dynamic> toJson() => _$ChecksumOptionToJson(this);
+}
+
 @JsonSerializable()
 class OptsExtraHttp {
   int connections;
@@ -25,6 +40,7 @@ class OptsExtraHttp {
   bool? autoExtract;
   String archivePassword;
   bool deleteAfterExtract;
+  ChecksumOption? checksum;
 
   OptsExtraHttp({
     this.connections = 0,
@@ -33,6 +49,7 @@ class OptsExtraHttp {
     this.autoExtract,
     this.archivePassword = '',
     this.deleteAfterExtract = false,
+    this.checksum,
   });
 
   factory OptsExtraHttp.fromJson(Map<String, dynamic> json) => _$OptsExtraHttpFromJson(json);

ui/flutter/lib/api/model/options.g.dart

@@ -22,6 +22,16 @@ Map<String, dynamic> _$OptionsToJson(Options instance) => <String, dynamic>{
   'extra': ?instance.extra,
 };
 
+ChecksumOption _$ChecksumOptionFromJson(Map<String, dynamic> json) => ChecksumOption(
+  algorithm: json['algorithm'] as String? ?? '',
+  expected: json['expected'] as String? ?? '',
+);
+
+Map<String, dynamic> _$ChecksumOptionToJson(ChecksumOption instance) => <String, dynamic>{
+  'algorithm': instance.algorithm,
+  'expected': instance.expected,
+};
+
 OptsExtraHttp _$OptsExtraHttpFromJson(Map<String, dynamic> json) => OptsExtraHttp(
   connections: (json['connections'] as num?)?.toInt() ?? 0,
   autoTorrent: json['autoTorrent'] as bool?,
@@ -29,6 +39,9 @@ OptsExtraHttp _$OptsExtraHttpFromJson(Map<String, dynamic> json) => OptsExtraHtt
   autoExtract: json['autoExtract'] as bool?,
   archivePassword: json['archivePassword'] as String? ?? '',
   deleteAfterExtract: json['deleteAfterExtract'] as bool? ?? false,
+  checksum: json['checksum'] == null
+      ? null
+      : ChecksumOption.fromJson(json['checksum'] as Map<String, dynamic>),
 );
 
 Map<String, dynamic> _$OptsExtraHttpToJson(OptsExtraHttp instance) => <String, dynamic>{
@@ -38,4 +51,5 @@ Map<String, dynamic> _$OptsExtraHttpToJson(OptsExtraHttp instance) => <String, d
   'autoExtract': ?instance.autoExtract,
   'archivePassword': instance.archivePassword,
   'deleteAfterExtract': instance.deleteAfterExtract,
+  'checksum': ?instance.checksum?.toJson(),
 };

ui/flutter/lib/features/tasks/presentation/pages/create_task_window_page.dart

@@ -66,6 +66,7 @@ class _CreateTaskWindowPageState extends ConsumerState<CreateTaskWindowPage> {
   final _httpHeadersController = AppHttpHeadersController(defaultNames: const ['User-Agent', 'Cookie', 'Referer']);
   final _trackersController = TextEditingController();
   final _archivePasswordController = TextEditingController();
+  final _checksumHashController = TextEditingController();
   final _formScrollController = ScrollController();
 
   String _httpMethod = 'GET';
@@ -74,6 +75,7 @@ class _CreateTaskWindowPageState extends ConsumerState<CreateTaskWindowPage> {
   Map<String, String>? _initialLabels;
   RequestProxyMode _proxyMode = RequestProxyMode.follow;
   String _proxyScheme = 'http';
+  String _checksumAlgorithm = 'sha256';
   bool _skipVerifyCert = false;
   bool? _autoTorrent;
   bool? _deleteTorrentAfterDownload;
@@ -134,6 +136,7 @@ class _CreateTaskWindowPageState extends ConsumerState<CreateTaskWindowPage> {
     _httpHeadersController.dispose();
     _trackersController.dispose();
     _archivePasswordController.dispose();
+    _checksumHashController.dispose();
     _formScrollController.dispose();
     super.dispose();
   }
@@ -243,6 +246,12 @@ class _CreateTaskWindowPageState extends ConsumerState<CreateTaskWindowPage> {
           _autoExtract = extra.autoExtract;
           _archivePasswordController.text = extra.archivePassword;
           _deleteAfterExtract = extra.deleteAfterExtract;
+          if (extra.checksum != null) {
+            if (extra.checksum!.algorithm.isNotEmpty) {
+              _checksumAlgorithm = extra.checksum!.algorithm;
+            }
+            _checksumHashController.text = extra.checksum!.expected;
+          }
         }
       }
     });
@@ -668,6 +677,32 @@ class _CreateTaskWindowPageState extends ConsumerState<CreateTaskWindowPage> {
                                   ),
                                 ),
                               ],
+                              const SizedBox(height: 14),
+                              AppFormPair(
+                                direction: stacked ? Axis.vertical : Axis.horizontal,
+                                firstLabel: 'Checksum Algorithm',
+                                secondLabel: 'Checksum Hash',
+                                firstFlex: 382,
+                                secondFlex: 618,
+                                first: AppChoiceSegmentedControl<String>(
+                                  key: const ValueKey('create-task-checksum-algorithm'),
+                                  showIcons: false,
+                                  value: _checksumAlgorithm,
+                                  buttonKeyPrefix: 'create-task-checksum-algorithm',
+                                  alignment: WrapAlignment.start,
+                                  options: const [
+                                    AppChoiceOption(value: 'md5', label: 'MD5', icon: Icons.tag),
+                                    AppChoiceOption(value: 'sha1', label: 'SHA-1', icon: Icons.tag),
+                                    AppChoiceOption(value: 'sha256', label: 'SHA-256', icon: Icons.tag),
+                                  ],
+                                  onChanged: (value) => setState(() => _checksumAlgorithm = value),
+                                ),
+                                second: _WindowTextField(
+                                  key: const ValueKey('create-task-checksum-expected'),
+                                  controller: _checksumHashController,
+                                  hintText: 'Expected hash (optional)',
+                                ),
+                              ),
                             ] else ...[
                               AppFormRow(
                                 direction: stacked ? Axis.vertical : Axis.horizontal,
@@ -1024,6 +1059,13 @@ class _CreateTaskWindowPageState extends ConsumerState<CreateTaskWindowPage> {
 
   api_options.Options _buildOptions({String? name, List<int> selectFiles = const []}) {
     final connections = int.tryParse(_connectionsController.text.trim()) ?? 0;
+    final checksumExpected = _checksumHashController.text.trim();
+    final checksum = checksumExpected.isNotEmpty
+        ? api_options.ChecksumOption(
+            algorithm: _checksumAlgorithm,
+            expected: checksumExpected,
+          )
+        : null;
     return api_options.Options(
       name: name ?? _renameController.text.trim(),
       path: _directoryController.text.trim(),
@@ -1036,6 +1078,7 @@ class _CreateTaskWindowPageState extends ConsumerState<CreateTaskWindowPage> {
         autoExtract: _autoExtract,
         archivePassword: _archivePasswordController.text,
         deleteAfterExtract: _deleteAfterExtract,
+        checksum: checksum,
       ).toJson(),
     );
   }