Reorganize packages pt 1

End goal: simplify build process

smtpd/mime.go

@@ -0,0 +1,209 @@
+package smtpd
+
+import (
+	"bytes"
+	"container/list"
+	"fmt"
+	"github.com/sloonz/go-qprintable"
+	"io"
+	"mime"
+	"mime/multipart"
+	"net/mail"
+	"strings"
+)
+
+type MIMENodeMatcher func(node *MIMENode) bool
+
+type MIMENode struct {
+	Parent      *MIMENode
+	FirstChild  *MIMENode
+	NextSibling *MIMENode
+	Type        string
+	Content     []byte
+}
+
+type MIMEBody struct {
+	Text string
+	Html string
+	Root *MIMENode
+}
+
+func NewMIMENode(parent *MIMENode, contentType string) *MIMENode {
+	return &MIMENode{Parent: parent, Type: contentType}
+}
+
+func (n *MIMENode) BreadthFirstSearch(matcher MIMENodeMatcher) *MIMENode {
+	q := list.New()
+	q.PushBack(n)
+
+	// Push children onto queue and attempt to match in that order
+	for q.Len() > 0 {
+		e := q.Front()
+		n := e.Value.(*MIMENode)
+		if matcher(n) {
+			return n
+		}
+		q.Remove(e)
+		c := n.FirstChild
+		for c != nil {
+			q.PushBack(c)
+			c = c.NextSibling
+		}
+	}
+
+	return nil
+}
+
+func (n *MIMENode) String() string {
+	children := ""
+	siblings := ""
+	if n.FirstChild != nil {
+		children = n.FirstChild.String()
+	}
+	if n.NextSibling != nil {
+		siblings = n.NextSibling.String()
+	}
+	return fmt.Sprintf("[%v %v] %v", n.Type, children, siblings)
+}
+
+func IsMIMEMessage(mailMsg *mail.Message) bool {
+	// Parse top-level multipart
+	ctype := mailMsg.Header.Get("Content-Type")
+	mediatype, _, err := mime.ParseMediaType(ctype)
+	if err != nil {
+		return false
+	}
+	switch mediatype {
+	case "multipart/alternative":
+		return true
+	}
+
+	return false
+}
+
+func ParseMIMEBody(mailMsg *mail.Message) (*MIMEBody, error) {
+	mimeMsg := new(MIMEBody)
+
+	if !IsMIMEMessage(mailMsg) {
+		// Parse as text only
+		bodyBytes, err := decodeSection(mailMsg.Header.Get("Content-Transfer-Encoding"), mailMsg.Body)
+		if err != nil {
+			return nil, err
+		}
+		mimeMsg.Text = string(bodyBytes)
+	} else {
+		// Parse top-level multipart
+		ctype := mailMsg.Header.Get("Content-Type")
+		mediatype, params, err := mime.ParseMediaType(ctype)
+		if err != nil {
+			return nil, err
+		}
+		switch mediatype {
+		case "multipart/alternative":
+			// Good
+		default:
+			return nil, fmt.Errorf("Unknown mediatype: %v", mediatype)
+		}
+		boundary := params["boundary"]
+		if boundary == "" {
+			return nil, fmt.Errorf("Unable to locate boundary param in Content-Type header")
+		}
+
+		// Root Node of our tree
+		root := NewMIMENode(nil, mediatype)
+		err = parseNodes(root, mailMsg.Body, boundary)
+
+		// Locate text body
+		match := root.BreadthFirstSearch(func(node *MIMENode) bool {
+			return node.Type == "text/plain"
+		})
+		if match != nil {
+			mimeMsg.Text = string(match.Content)
+		}
+
+		// Locate HTML body
+		match = root.BreadthFirstSearch(func(node *MIMENode) bool {
+			return node.Type == "text/html"
+		})
+		if match != nil {
+			mimeMsg.Html = string(match.Content)
+		}
+	}
+
+	return mimeMsg, nil
+}
+
+func (m *MIMEBody) String() string {
+	return fmt.Sprintf("----TEXT----\n%v\n----HTML----\n%v\n----END----\n", m.Text, m.Html)
+}
+
+// decodeSection attempts to decode the data from reader using the algorithm listed in
+// the Content-Transfer-Encoding header, returning the raw data if it does not know
+// the encoding type.
+func decodeSection(encoding string, reader io.Reader) ([]byte, error) {
+	switch strings.ToLower(encoding) {
+	case "quoted-printable":
+		decoder := qprintable.NewDecoder(qprintable.WindowsTextEncoding, reader)
+		buf := new(bytes.Buffer)
+		_, err := buf.ReadFrom(decoder)
+		if err != nil {
+			return nil, err
+		}
+		return buf.Bytes(), nil
+	}
+	// Don't know this type, just return bytes
+	buf := new(bytes.Buffer)
+	_, err := buf.ReadFrom(reader)
+	if err != nil {
+		return nil, err
+	}
+	return buf.Bytes(), nil
+}
+
+func parseNodes(parent *MIMENode, reader io.Reader, boundary string) error {
+	var prevSibling *MIMENode
+
+	// Loop over MIME parts
+	mr := multipart.NewReader(reader, boundary)
+	for {
+		part, err := mr.NextPart()
+		if err != nil {
+			if err == io.EOF {
+				// This is a clean end-of-message signal
+				break
+			}
+			return err
+		}
+		mediatype, params, err := mime.ParseMediaType(part.Header.Get("Content-Type"))
+		if err != nil {
+			return err
+		}
+
+		// Insert ourselves into tree
+		node := NewMIMENode(parent, mediatype)
+		if prevSibling != nil {
+			prevSibling.NextSibling = node
+		} else {
+			parent.FirstChild = node
+		}
+		prevSibling = node
+
+		boundary := params["boundary"]
+		if boundary != "" {
+			// Content is another multipart
+			err = parseNodes(node, part, boundary)
+			if err != nil {
+				return err
+			}
+		} else {
+			// Content is text or data, decode it
+			data, err := decodeSection(part.Header.Get("Content-Transfer-Encoding"), part)
+			if err != nil {
+				return err
+			}
+			node.Content = data
+		}
+	}
+
+	return nil
+}