Display & download any message part

imap.go

@@ -3,7 +3,6 @@ package koushin
 import (
 	"bufio"
 	"fmt"
-	"io/ioutil"
 	"sort"
 	"strconv"
 	"strings"
@@ -140,10 +139,11 @@ func (msg *imapMessage) TextPartName() string {
 type IMAPPartNode struct {
 	Path     []int
 	MIMEType string
+	Filename string
 	Children []IMAPPartNode
 }
 
-func (node *IMAPPartNode) PathString() string {
+func (node IMAPPartNode) PathString() string {
 	l := make([]string, len(node.Path))
 	for i, partNum := range node.Path {
 		l[i] = strconv.Itoa(partNum)
@@ -152,14 +152,32 @@ func (node *IMAPPartNode) PathString() string {
 	return strings.Join(l, ".")
 }
 
+func (node IMAPPartNode) IsText() bool {
+	return strings.HasPrefix(strings.ToLower(node.MIMEType), "text/")
+}
+
+func (node IMAPPartNode) String() string {
+	if node.Filename != "" {
+		return fmt.Sprintf("%s (%s)", node.Filename, node.MIMEType)
+	} else {
+		return node.MIMEType
+	}
+}
+
 func imapPartTree(bs *imap.BodyStructure, path []int) *IMAPPartNode {
 	if !strings.EqualFold(bs.MIMEType, "multipart") && len(path) == 0 {
 		path = []int{1}
 	}
 
+	var filename string
+	if strings.EqualFold(bs.Disposition, "attachment") {
+		filename = bs.DispositionParams["filename"]
+	}
+
 	node := &IMAPPartNode{
 		Path:     path,
 		MIMEType: strings.ToLower(bs.MIMEType + "/" + bs.MIMESubType),
+		Filename: filename,
 		Children: make([]IMAPPartNode, len(bs.Parts)),
 	}
 
@@ -225,56 +243,52 @@ func listMessages(conn *imapclient.Client, mboxName string) ([]imapMessage, erro
 	return msgs, nil
 }
 
-func getMessage(conn *imapclient.Client, mboxName string, uid uint32, partPath []int) (*imapMessage, string, error) {
+func getMessagePart(conn *imapclient.Client, mboxName string, uid uint32, partPath []int) (*imapMessage, *message.Entity, error) {
 	if err := ensureMailboxSelected(conn, mboxName); err != nil {
-		return nil, "", err
+		return nil, nil, err
 	}
 
 	seqSet := new(imap.SeqSet)
 	seqSet.AddNum(uid)
 
-	var textHeaderSection imap.BodySectionName
-	textHeaderSection.Peek = true
-	textHeaderSection.Specifier = imap.HeaderSpecifier
-	textHeaderSection.Path = partPath
+	var partHeaderSection imap.BodySectionName
+	partHeaderSection.Peek = true
+	partHeaderSection.Specifier = imap.HeaderSpecifier
+	partHeaderSection.Path = partPath
 
-	var textBodySection imap.BodySectionName
-	textBodySection.Peek = true
-	textBodySection.Path = partPath
+	var partBodySection imap.BodySectionName
+	partBodySection.Peek = true
+	partBodySection.Specifier = imap.TextSpecifier
+	partBodySection.Path = partPath
 
 	fetch := []imap.FetchItem{
 		imap.FetchEnvelope,
 		imap.FetchUid,
 		imap.FetchBodyStructure,
-		textHeaderSection.FetchItem(),
-		textBodySection.FetchItem(),
+		partHeaderSection.FetchItem(),
+		partBodySection.FetchItem(),
 	}
 
 	ch := make(chan *imap.Message, 1)
 	if err := conn.UidFetch(seqSet, fetch, ch); err != nil {
-		return nil, "", err
+		return nil, nil, err
 	}
 
 	msg := <-ch
 	if msg == nil {
-		return nil, "", fmt.Errorf("server didn't return message")
+		return nil, nil, fmt.Errorf("server didn't return message")
 	}
 
-	headerReader := bufio.NewReader(msg.GetBody(&textHeaderSection))
+	headerReader := bufio.NewReader(msg.GetBody(&partHeaderSection))
 	h, err := textproto.ReadHeader(headerReader)
 	if err != nil {
-		return nil, "", err
-	}
-
-	text, err := message.New(message.Header{h}, msg.GetBody(&textBodySection))
-	if err != nil {
-		return nil, "", err
+		return nil, nil, err
 	}
 
-	b, err := ioutil.ReadAll(text.Body)
+	part, err := message.New(message.Header{h}, msg.GetBody(&partBodySection))
 	if err != nil {
-		return nil, "", err
+		return nil, nil, err
 	}
 
-	return &imapMessage{msg}, string(b), nil
+	return &imapMessage{msg}, part, nil
 }

public/message.html

@@ -6,21 +6,42 @@
 
 <h2>{{.Message.Envelope.Subject}}</h2>
 
-{{define "message-part"}}
-	<a href="?part={{.PathString}}">{{.MIMEType}}</a>
-	{{if gt (len .Children) 0}}
-	<ul>
-		{{range .Children}}
-			<li>{{template "message-part" .}}</li>
+{{define "message-part-tree"}}
+	{{/* nested templates can't access the parent's context */}}
+	{{$ = index . 0}}
+	{{with index . 1}}
+		<a
+			{{if .IsText}}
+				href="{{$.Message.Uid}}?part={{.PathString}}"
+			{{else}}
+				href="{{$.Message.Uid}}/raw?part={{.PathString}}"
+			{{end}}
+		>
+			{{if eq $.PartPath .PathString}}<strong>{{end}}
+			{{.String}}
+			{{if eq $.PartPath .PathString}}</strong>{{end}}
+		</a>
+		{{if gt (len .Children) 0}}
+		<ul>
+			{{range .Children}}
+				<li>{{template "message-part-tree" (tuple $ .)}}</li>
+			{{end}}
+		</ul>
 		{{end}}
-	</ul>
 	{{end}}
 {{end}}
 
-{{template "message-part" .Message.PartTree}}
+<p>Parts:</p>
+
+{{template "message-part-tree" (tuple $ .Message.PartTree)}}
+
+<hr>
 
 {{if .Body}}
 	<pre>{{.Body}}</pre>
+{{else}}
+	<p>Can't preview this message part.</p>
+	<a href="{{.Message.Uid}}/raw?part={{.PartPath}}">Download</a>
 {{end}}
 
 {{template "foot"}}

server.go

@@ -2,8 +2,11 @@ package koushin
 
 import (
 	"fmt"
+	"io/ioutil"
+	"mime"
 	"net/http"
 	"net/url"
+	"strings"
 	"time"
 
 	imapclient "github.com/emersion/go-imap/client"
@@ -94,6 +97,63 @@ func handleLogin(ectx echo.Context) error {
 	return ctx.Render(http.StatusOK, "login.html", nil)
 }
 
+func handleGetPart(ctx *context, raw bool) error {
+	mboxName := ctx.Param("mbox")
+	uid, err := parseUid(ctx.Param("uid"))
+	if err != nil {
+		return echo.NewHTTPError(http.StatusBadRequest, err)
+	}
+	partPathString := ctx.QueryParam("part")
+	partPath, err := parsePartPath(partPathString)
+	if err != nil {
+		return echo.NewHTTPError(http.StatusBadRequest, err)
+	}
+
+	msg, part, err := getMessagePart(ctx.conn, mboxName, uid, partPath)
+	if err != nil {
+		return err
+	}
+
+	mimeType, _, err := part.Header.ContentType()
+	if err != nil {
+		return err
+	}
+	if len(partPath) == 0 {
+		mimeType = "message/rfc822"
+	}
+
+	if raw {
+		disp, dispParams, _ := part.Header.ContentDisposition()
+		filename := dispParams["filename"]
+
+		if !strings.EqualFold(mimeType, "text/plain") || strings.EqualFold(disp, "attachment") {
+			dispParams := make(map[string]string)
+			if filename != "" {
+				dispParams["filename"] = filename
+			}
+			disp := mime.FormatMediaType("attachment", dispParams)
+			ctx.Response().Header().Set("Content-Disposition", disp)
+		}
+		return ctx.Stream(http.StatusOK, mimeType, part.Body)
+	}
+
+	var body string
+	if strings.HasPrefix(strings.ToLower(mimeType), "text/") {
+		b, err := ioutil.ReadAll(part.Body)
+		if err != nil {
+			return err
+		}
+		body = string(b)
+	}
+
+	return ctx.Render(http.StatusOK, "message.html", map[string]interface{}{
+		"Mailbox":  ctx.conn.Mailbox(),
+		"Message":  msg,
+		"Body":     body,
+		"PartPath": partPathString,
+	})
+}
+
 func New(imapURL string) *echo.Echo {
 	e := echo.New()
 
@@ -157,27 +217,11 @@ func New(imapURL string) *echo.Echo {
 
 	e.GET("/message/:mbox/:uid", func(ectx echo.Context) error {
 		ctx := ectx.(*context)
-
-		uid, err := parseUid(ctx.Param("uid"))
-		if err != nil {
-			return echo.NewHTTPError(http.StatusBadRequest, err)
-		}
-		// TODO: handle messages without a text part
-		part, err := parsePartPath(ctx.QueryParam("part"))
-		if err != nil {
-			return echo.NewHTTPError(http.StatusBadRequest, err)
-		}
-
-		msg, body, err := getMessage(ctx.conn, ctx.Param("mbox"), uid, part)
-		if err != nil {
-			return err
-		}
-
-		return ctx.Render(http.StatusOK, "message.html", map[string]interface{}{
-			"Mailbox": ctx.conn.Mailbox(),
-			"Message": msg,
-			"Body":    body,
-		})
+		return handleGetPart(ctx, false)
+	})
+	e.GET("/message/:mbox/:uid/raw", func(ectx echo.Context) error {
+		ctx := ectx.(*context)
+		return handleGetPart(ctx, true)
 	})
 
 	e.GET("/login", handleLogin)

strconv.go

@@ -18,6 +18,10 @@ func parseUid(s string) (uint32, error) {
 }
 
 func parsePartPath(s string) ([]int, error) {
+	if s == "" {
+		return nil, nil
+	}
+
 	l := strings.Split(s, ".")
 	path := make([]int, len(l))
 	for i, s := range l {

template.go

@@ -16,6 +16,10 @@ func (t *tmpl) Render(w io.Writer, name string, data interface{}, c echo.Context
 }
 
 func loadTemplates() (*tmpl, error) {
-	t, err := template.New("drmdb").ParseGlob("public/*.html")
+	t, err := template.New("drmdb").Funcs(template.FuncMap{
+		"tuple": func(values ...interface{}) []interface{} {
+			return values
+		},
+	}).ParseGlob("public/*.html")
 	return &tmpl{t}, err
 }