Properly handle different attachment use cases

server/util.go

@@ -0,0 +1,68 @@
+package server
+
+import (
+	"fmt"
+	"heckel.io/ntfy/util"
+	"io"
+	"net/http"
+	"net/url"
+	"path"
+	"strconv"
+	"time"
+)
+
+const (
+	peakAttachmentTimeout    = 2500 * time.Millisecond
+	peakAttachmeantReadBytes = 128
+)
+
+func maybePeakAttachmentURL(m *message) error {
+	return maybePeakAttachmentURLInternal(m, peakAttachmentTimeout)
+}
+
+func maybePeakAttachmentURLInternal(m *message, timeout time.Duration) error {
+	if m.Attachment == nil || m.Attachment.URL == "" {
+		return nil
+	}
+	client := http.Client{
+		Timeout: timeout,
+		Transport: &http.Transport{
+			DisableCompression: true, // Disable "Accept-Encoding: gzip", otherwise we won't get the Content-Length
+			Proxy:              http.ProxyFromEnvironment,
+		},
+	}
+	req, err := http.NewRequest(http.MethodGet, m.Attachment.URL, nil)
+	if err != nil {
+		return err
+	}
+	req.Header.Set("User-Agent", "ntfy")
+	resp, err := client.Do(req)
+	if err != nil {
+		return errHTTPBadRequestAttachmentURLPeakGeneral
+	}
+	defer resp.Body.Close()
+	if resp.StatusCode < 200 || resp.StatusCode > 299 {
+		return errHTTPBadRequestAttachmentURLPeakNon2xx
+	}
+	if size, err := strconv.ParseInt(resp.Header.Get("Content-Length"), 10, 64); err == nil {
+		m.Attachment.Size = size
+	}
+	m.Attachment.Type = resp.Header.Get("Content-Type")
+	if m.Attachment.Type == "" || m.Attachment.Type == "application/octet-stream" {
+		buf := make([]byte, peakAttachmeantReadBytes)
+		io.ReadFull(resp.Body, buf) // Best effort: We don't care about the error
+		m.Attachment.Type = http.DetectContentType(buf)
+	}
+	if m.Attachment.Name == "" {
+		u, err := url.Parse(m.Attachment.URL)
+		if err != nil {
+			m.Attachment.Name = fmt.Sprintf("attachment%s", util.ExtensionByType(m.Attachment.Type))
+		} else {
+			m.Attachment.Name = path.Base(u.Path)
+			if m.Attachment.Name == "." || m.Attachment.Name == "/" {
+				m.Attachment.Name = fmt.Sprintf("attachment%s", util.ExtensionByType(m.Attachment.Type))
+			}
+		}
+	}
+	return nil
+}