first commit

internal/smtpserver/attachments.go

@@ -0,0 +1,109 @@
+package smtpserver
+
+import (
+	"bytes"
+	"io"
+	"mime"
+	"mime/multipart"
+	"net/mail"
+	"path/filepath"
+	"strings"
+	"time"
+)
+
+// attachmentStoragePath mirrors smtp_handler.get_attachment_storage_path:
+// {base}/{safe_domain}/{username_or_ip}/{YYYY-DD-MMM}/
+func attachmentStoragePath(base, domain, usernameOrIP string, now time.Time) string {
+	safeDomain := sanitizePathSegment(domain, "/\\")
+	dateFolder := now.Format("2006-02-Jan")
+	parts := []string{base, safeDomain}
+	if usernameOrIP != "" {
+		parts = append(parts, usernameOrIP)
+	}
+	parts = append(parts, dateFolder)
+	return filepath.Join(parts...)
+}
+
+func sanitizePathSegment(s string, chars string) string {
+	for _, c := range chars {
+		s = strings.ReplaceAll(s, string(c), "_")
+	}
+	return s
+}
+
+// cleanMessageIDPrefix strips everything from "@" onward, mirroring the
+// clean_message_id computation used to build attachment filenames.
+func cleanMessageIDPrefix(messageID string) string {
+	if i := strings.Index(messageID, "@"); i >= 0 {
+		return messageID[:i]
+	}
+	return messageID
+}
+
+type attachmentPart struct {
+	Filename    string
+	ContentType string
+	Data        []byte
+}
+
+type parsedMessage struct {
+	HeaderLines []string // "Name: value" per header, in order
+	BodyText    string   // concatenated text/* parts
+	Attachments []attachmentPart
+}
+
+// parseMessage mirrors the repeated BytesParser(policy=policy.default) passes in
+// handle_DATA: it extracts header lines for logging, concatenated text body, and any
+// attachment parts (Content-Disposition: attachment with a filename).
+func parseMessage(raw []byte) (*parsedMessage, error) {
+	msg, err := mail.ReadMessage(bytes.NewReader(raw))
+	if err != nil {
+		return nil, err
+	}
+	out := &parsedMessage{}
+	for k, vs := range msg.Header {
+		for _, v := range vs {
+			out.HeaderLines = append(out.HeaderLines, k+": "+v)
+		}
+	}
+
+	contentType := msg.Header.Get("Content-Type")
+	mediaType, params, err := mime.ParseMediaType(contentType)
+	if err != nil {
+		mediaType = "text/plain"
+	}
+
+	if strings.HasPrefix(mediaType, "multipart/") {
+		mr := multipart.NewReader(msg.Body, params["boundary"])
+		for {
+			part, err := mr.NextPart()
+			if err == io.EOF {
+				break
+			}
+			if err != nil {
+				break
+			}
+			data, _ := io.ReadAll(part)
+			disp, dispParams, _ := mime.ParseMediaType(part.Header.Get("Content-Disposition"))
+			partCT := part.Header.Get("Content-Type")
+			partMediaType, _, _ := mime.ParseMediaType(partCT)
+
+			if disp == "attachment" && dispParams["filename"] != "" {
+				out.Attachments = append(out.Attachments, attachmentPart{
+					Filename:    dispParams["filename"],
+					ContentType: getContentType(partMediaType, dispParams["filename"]),
+					Data:        data,
+				})
+				continue
+			}
+			if strings.HasPrefix(partMediaType, "text/") && disp != "attachment" {
+				out.BodyText += string(data) + "\n"
+			}
+		}
+	} else if strings.HasPrefix(mediaType, "text/") {
+		data, _ := io.ReadAll(msg.Body)
+		out.BodyText = string(data)
+	}
+	out.BodyText = strings.TrimSpace(out.BodyText)
+	return out, nil
+}