fix: ensure relative CID images load in web views

cmd/archive.go

@@ -244,6 +244,10 @@ func (a *App) compileArchiveCampaigns(camps []models.Campaign) ([]manager.Campai
 	)
 	for _, c := range camps {
 		camp := c
+
+		// Resolve data-embed images to media URLs as cid: cannot resolve on a web page.
+		a.manager.ApplyArchiveImages(&camp)
+
 		if err := camp.CompileTemplate(a.manager.TemplateFuncs(&camp)); err != nil {
 			a.log.Printf("error compiling template: %v", err)
 			return nil, echo.NewHTTPError(http.StatusInternalServerError, a.i18n.T("public.errorFetchingCampaign"))

cmd/manager_store.go

@@ -128,6 +128,16 @@ func (s *store) GetInlineAttachmentByFilename(filename string) (models.Attachmen
 	}, cid, nil
 }
 
+// GetMediaURLByFilename returns the public URL of a media item by filename.
+func (s *store) GetMediaURLByFilename(filename string) (string, error) {
+	m, err := s.core.GetMedia(0, "", filename, s.media)
+	if err != nil {
+		return "", err
+	}
+
+	return m.URL, nil
+}
+
 // CreateLink registers a URL with a UUID for tracking clicks and returns the UUID.
 func (s *store) CreateLink(url string) (string, error) {
 	// Create a new UUID for the URL. If the URL already exists in the DB

cmd/public.go

@@ -174,6 +174,9 @@ func (a *App) ViewCampaignMessage(c echo.Context) error {
 			makeMsgTpl(a.i18n.T("public.errorTitle"), "", a.i18n.Ts("public.errorFetchingCampaign")))
 	}
 
+	// Resolve data-embed images to media URLs as cid: cannot resolve on a web page.
+	a.manager.ApplyArchiveImages(&camp)
+
 	// Compile the template.
 	if err := camp.CompileTemplate(a.manager.TemplateFuncs(&camp)); err != nil {
 		a.log.Printf("error compiling template: %v", err)

internal/manager/manager.go

@@ -52,6 +52,7 @@ type Store interface {
 	GetCampaign(campID int) (*models.Campaign, error)
 	GetAttachment(mediaID int) (models.Attachment, error)
 	GetInlineAttachmentByFilename(filename string) (models.Attachment, string, error)
+	GetMediaURLByFilename(filename string) (string, error)
 	UpdateCampaignStatus(campID int, status string) error
 	UpdateCampaignCounts(campID int, toSend int, sent int, lastSubID int) error
 	CreateLink(url string) (string, error)
@@ -766,6 +767,51 @@ func (m *Manager) applyInlineImages(body string, cache map[string]string) (strin
 	return out, atts
 }
 
+// ApplyArchiveImages resolves any <img ... data-embed ...> tags in the campaign
+// body and template body to public media URLs. The archive is rendered as a
+// standalone HTML page and not a MIME message, so cid: cannot resolve there.
+func (m *Manager) ApplyArchiveImages(c *models.Campaign) {
+	if c.ContentType == models.CampaignContentTypePlain {
+		return
+	}
+
+	cache := make(map[string]string)
+	c.Body = m.applyArchiveImages(c.Body, cache)
+	c.TemplateBody = m.applyArchiveImages(c.TemplateBody, cache)
+}
+
+func (m *Manager) applyArchiveImages(body string, cache map[string]string) string {
+	if !strings.Contains(body, attribInlineEmbed) {
+		return body
+	}
+
+	return reInlineImage.ReplaceAllStringFunc(body, func(tag string) string {
+		src := extractSrc(tag)
+		if src == "" || strings.HasPrefix(strings.ToLower(src), "cid:") {
+			return tag
+		}
+
+		fname := filenameFromSrc(src)
+		if fname == "" {
+			return tag
+		}
+
+		u, ok := cache[src]
+		if !ok {
+			s, err := m.store.GetMediaURLByFilename(fname)
+			if err != nil {
+				m.log.Printf("archive image %q not resolved: %v", src, err)
+			}
+			u = s
+			cache[src] = u
+		}
+		if u == "" {
+			return tag
+		}
+		return reImgSrc.ReplaceAllString(tag, `${1}src="`+u+`"`)
+	})
+}
+
 // MakeContentID returns a standard `Content-ID` value (without  the angle brackets).
 func MakeContentID(key string) string {
 	sum := sha1.Sum([]byte(key))