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fix(matrix): add size limit for media downloads

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Replace DownloadBytes with streaming Download to avoid loading large
files into memory. Add 10MB size limit for downloaded media files.

Fixes #1405
This commit is contained in:
曾文锋0668000834 2026-03-12 20:47:06 +08:00
parent 95716b106b
commit 252ed37ac3
1 changed files with 54 additions and 11 deletions
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61
pkg/channels/matrix/matrix.go
View file

@ -4,6 +4,7 @@ import (
"context"
"fmt"
"html"
"io"
"mime"
"net/url"
"os"
@ -458,7 +459,7 @@ func (c *MatrixChannel) SendPlaceholder(ctx context.Context, chatID string) (str
text := strings.TrimSpace(c.config.Placeholder.Text)
if text == "" {
text = "Thinking... 💭"
text = "Thinking..."
}
resp, err := c.client.SendMessageEvent(ctx, roomID, event.EventMessage, &event.MessageEventContent{
@ -693,6 +694,9 @@ func (c *MatrixChannel) storeMedia(localPath string, meta media.MediaMeta, scope
return localPath
}
// defaultMaxMediaSize is the default maximum size for downloaded media (10MB).
const defaultMaxMediaSize = 10 * 1024 * 1024
func (c *MatrixChannel) downloadMedia(
ctx context.Context,
msgEvt *event.MessageEventContent,
@ -714,17 +718,16 @@ func (c *MatrixChannel) downloadMedia(
reqCtx, cancel := context.WithTimeout(dlCtx, 20*time.Second)
defer cancel()
data, err := c.client.DownloadBytes(reqCtx, parsed)
// Use streaming download instead of DownloadBytes to avoid loading large files into memory
resp, err := c.client.Download(reqCtx, parsed)
if err != nil {
return "", err
}
defer resp.Body.Close()
// Encrypted attachments put URL in msgEvt.File and require client-side decryption.
if msgEvt != nil && msgEvt.File != nil && msgEvt.URL == "" {
err = msgEvt.File.DecryptInPlace(data)
if err != nil {
return "", fmt.Errorf("decrypt matrix media: %w", err)
}
// Check Content-Length header if available
if resp.ContentLength > defaultMaxMediaSize {
return "", fmt.Errorf("media file too large: %d bytes (max %d)", resp.ContentLength, defaultMaxMediaSize)
}
label := matrixMediaLabel(msgEvt, mediaKind)
@ -739,10 +742,50 @@ func (c *MatrixChannel) downloadMedia(
}
defer tmp.Close()
if _, err = tmp.Write(data); err != nil {
// Stream data to file with size limit
var totalBytes int64
buf := make([]byte, 32*1024) // 32KB buffer
for {
n, err := resp.Body.Read(buf)
if n > 0 {
totalBytes += int64(n)
if totalBytes > defaultMaxMediaSize {
_ = os.Remove(tmp.Name())
return "", fmt.Errorf("media file too large (exceeded %d bytes)", defaultMaxMediaSize)
}
if _, writeErr := tmp.Write(buf[:n]); writeErr != nil {
_ = os.Remove(tmp.Name())
return "", writeErr
}
}
if err == io.EOF {
break
}
if err != nil {
_ = os.Remove(tmp.Name())
return "", err
}
}
// Encrypted attachments put URL in msgEvt.File and require client-side decryption.
if msgEvt != nil && msgEvt.File != nil && msgEvt.URL == "" {
// For encrypted files, we need to read and decrypt in memory
data, err := os.ReadFile(tmp.Name())
if err != nil {
_ = os.Remove(tmp.Name())
return "", fmt.Errorf("read encrypted file: %w", err)
}
err = msgEvt.File.DecryptInPlace(data)
if err != nil {
_ = os.Remove(tmp.Name())
return "", fmt.Errorf("decrypt matrix media: %w", err)
}
// Write decrypted data back
if err := os.WriteFile(tmp.Name(), data, 0600); err != nil {
_ = os.Remove(tmp.Name())
return "", fmt.Errorf("write decrypted file: %w", err)
}
}
return tmp.Name(), nil
}