emersion · tristan957 · Aug 4, 2023 · emersion · Oct 5, 2023 · emersion
diff --git a/mail/header.go b/mail/header.go
@@ -6,6 +6,7 @@ import (
 	"errors"
 	"fmt"
 	"net/mail"
+	"net/url"
 	"os"
 	"strconv"
 	"strings"
@@ -211,6 +212,61 @@ func (p *headerParser) parseMsgID() (string, error) {
 	return left + "@" + right, nil
 }
 
+func (p *headerParser) parseListCommand() (*url.URL, error) {
+	if !p.skipCFWS() {
+		return nil, errors.New("mail: malformed parenthetical comment")
+	}
+
+	// Consume a potential newline + indent.
+	p.consume('\r')
+	p.consume('\n')
+	p.skipSpace()
+
+	if p.consume('N') && p.consume('O') {
+		if !p.skipCFWS() {
+			return nil, errors.New("mail: malformed parenthetical comment")
+		}
+
+		return nil, nil
+	}
+
+	if !p.consume('<') {
+		return nil, errors.New("mail: missing '<' in list command")
+	}
+
+	i := 0
+	for p.s[i] != '>' && i+1 < len(p.s) {
+		i += 1
+	}
+
+	var lit string
+	lit, p.s = p.s[:i], p.s[i:]
+
+	u, err := url.Parse(lit)
+	if err != nil {
+		return u, errors.New("mail: malformed URL")
+	}
+
+	if !p.consume('>') {
+		return nil, errors.New("mail: missing '>' in list command")
+	}
+
+	if !p.skipCFWS() {
+		return nil, errors.New("mail: malformed parenthetical comment")
+	}
+
+	// If there isn't a comma, we don't care because it means that there aren't
+	// any other list command URLs.
+	p.consume(',')
+	p.skipSpace()
+
+	// Consume a potential newline.
+	p.consume('\r')
+	p.consume('\n')
+
+	return u, nil
+}
+
 // A Header is a mail header.
 type Header struct {
 	message.Header
@@ -308,6 +364,35 @@ func (h *Header) MsgIDList(key string) ([]string, error) {
 	return l, nil
 }
 
+// MsgIDList parses a list of URLs from a list command header. It returns URLs.
+// If the header field is missing, it returns nil.
+//
+// This can be used on List-Help, List-Unsubscribe, List-Subscribe, List-Post,
+// List-Owner, and List-Archive headers.
+//
+// See https://www.rfc-editor.org/rfc/rfc2369 for more information.
+//
+// In the case that the value of List-Post is the special value, "NO", the
+// return value is a slice containing one element, nil.
+func (h *Header) ListCommandURLList(key string) ([]*url.URL, error) {
+	v := h.Get(key)
+	if v == "" {
+		return nil, nil
+	}
+
+	p := headerParser{v}
+	var l []*url.URL
+	for !p.empty() {
+		url, err := p.parseListCommand()
+		if err != nil {
+			return l, err
+		}
+		l = append(l, url)
+	}
+
+	return l, nil
+}
+
 // GenerateMessageID wraps GenerateMessageIDWithHostname and therefore uses the
 // hostname of the local machine. This is done to not break existing software.
 // Wherever possible better use GenerateMessageIDWithHostname, because the local
@@ -362,6 +447,18 @@ func (h *Header) SetMsgIDList(key string, l []string) {
 	}
 }
 
+func (h *Header) SetListCommandURLList(key string, urls []*url.URL) {
+	if len(urls) == 0 {
+		h.Del(key)
+	}
+
+	var ids []string
+	for _, url := range urls {
+		ids = append(ids, url.String())
+	}
+	h.Set(key, "<"+strings.Join(ids, ">, <")+">")
+}
+
 // Copy creates a stand-alone copy of the header.
 func (h *Header) Copy() Header {
 	return Header{h.Header.Copy()}

diff --git a/mail/header_test.go b/mail/header_test.go
@@ -4,6 +4,7 @@ import (
 	"bufio"
 	"bytes"
 	netmail "net/mail"
+	"net/url"
 	"reflect"
 	"strings"
 	"testing"
@@ -215,3 +216,224 @@ func TestHeader_EmptyAddressList(t *testing.T) {
 	}
 
 }
+
+func TestHeader_ListCommandURLList(t *testing.T) {
+	tests := []struct {
+		header string
+		raw    string
+		urls   []*url.URL
+		xfail  bool
+	}{
+		{
+			header: "List-Help",
+			raw:    "<mailto:hello@example.com",
+			xfail:  true,
+		},
+		// These tests might seem repetitive, but they are the examples given at
+		// https://www.rfc-editor.org/rfc/rfc2369.
+		{
+			header: "List-Help",
+			raw:    "<mailto:list@host.com?subject=help> (List Instructions)",
+			urls: []*url.URL{
+				{Scheme: "mailto", Opaque: "list@host.com", RawQuery: "subject=help"},
+			},
+		},
+		{
+			header: "List-Help",
+			raw:    "<mailto:list-manager@host.com?body=info>",
+			urls: []*url.URL{
+				{Scheme: "mailto", Opaque: "list-manager@host.com", RawQuery: "body=info"},
+			},
+		},
+		{
+			header: "List-Help",
+			raw:    "<mailto:list-info@host.com> (Info about the list)",
+			urls: []*url.URL{
+				{Scheme: "mailto", Opaque: "list-info@host.com"},
+			},
+		},
+		{
+			header: "List-Help",
+			raw:    "<http://www.host.com/list/>, <mailto:list-info@host.com>",
+			urls: []*url.URL{
+				{Scheme: "http", Host: "www.host.com", Path: "/list/"},
+				{Scheme: "mailto", Opaque: "list-info@host.com"},
+			},
+		},
+		{
+			header: "List-Help",
+			raw:    "<ftp://ftp.host.com/list.txt> (FTP),\r\n\t<mailto:list@host.com?subject=help>",
+			urls: []*url.URL{
+				{Scheme: "ftp", Host: "ftp.host.com", Path: "/list.txt"},
+				{Scheme: "mailto", Opaque: "list@host.com", RawQuery: "subject=help"},
+			},
+		},
+		{
+			header: "List-Unsubscribe",
+			raw:    "<mailto:list@host.com?subject=unsubscribe>",
+			urls: []*url.URL{
+				{Scheme: "mailto", Opaque: "list@host.com", RawQuery: "subject=unsubscribe"},
+			},
+		},
+		{
+			header: "List-Unsubscribe",
+			raw:    "(Use this command to get off the list)\r\n\t<mailto:list-manager@host.com?body=unsubscribe%20list>",
+			urls: []*url.URL{
+				{Scheme: "mailto", Opaque: "list-manager@host.com", RawQuery: "body=unsubscribe%20list"},
+			},
+		},
+		{
+			header: "List-Unsubscribe",
+			raw:    "<mailto:list-off@host.com>",
+			urls: []*url.URL{
+				{Scheme: "mailto", Opaque: "list-off@host.com"},
+			},
+		},
+		{
+			header: "List-Unsubscribe",
+			raw:    "<http://www.host.com/list.cgi?cmd=unsub&lst=list>,\r\n\t<mailto:list-request@host.com?subject=unsubscribe>",
+			urls: []*url.URL{
+				{Scheme: "http", Host: "www.host.com", Path: "/list.cgi", RawQuery: "cmd=unsub&lst=list"},
+				{Scheme: "mailto", Opaque: "list-request@host.com", RawQuery: "subject=unsubscribe"},
+			},
+		},
+		{
+			header: "List-Subscribe",
+			raw:    "<mailto:list@host.com?subject=subscribe>",
+			urls: []*url.URL{
+				{Scheme: "mailto", Opaque: "list@host.com", RawQuery: "subject=subscribe"},
+			},
+		},
+		{
+			header: "List-Subscribe",
+			raw:    "(Use this command to join the list)\r\n\t<mailto:list-manager@host.com?body=subscribe%20list>",
+			urls: []*url.URL{
+				{Scheme: "mailto", Opaque: "list-manager@host.com", RawQuery: "body=subscribe%20list"},
+			},
+		},
+		{
+			header: "List-Unsubscribe",
+			raw:    "<mailto:list-on@host.com>",
+			urls: []*url.URL{
+				{Scheme: "mailto", Opaque: "list-on@host.com"},
+			},
+		},
+		{
+			header: "List-Subscribe",
+			raw:    "<http://www.host.com/list.cgi?cmd=sub&lst=list>,\r\n\t<mailto:list-manager@host.com?subject=subscribe>",
+			urls: []*url.URL{
+				{Scheme: "http", Host: "www.host.com", Path: "/list.cgi", RawQuery: "cmd=sub&lst=list"},
+				{Scheme: "mailto", Opaque: "list-manager@host.com", RawQuery: "subject=subscribe"},
+			},
+		},
+		{
+			header: "List-Post",
+			raw:    "<mailto:list@host.com>",
+			urls: []*url.URL{
+				{Scheme: "mailto", Opaque: "list@host.com"},
+			},
+		},
+		{
+			header: "List-Post",
+			raw:    "<mailto:moderator@host.com> (Postings are Moderated)",
+			urls: []*url.URL{
+				{Scheme: "mailto", Opaque: "moderator@host.com"},
+			},
+		},
+		{
+			header: "List-Post",
+			raw:    "<mailto:moderator@host.com?subject=list%20posting>",
+			urls: []*url.URL{
+				{Scheme: "mailto", Opaque: "moderator@host.com", RawQuery: "subject=list%20posting"},
+			},
+		},
+		{
+			header: "List-Post",
+			raw:    "NO (posting not allowed on this list)",
+			urls:   []*url.URL{nil},
+		},
+		{
+			header: "List-Owner",
+			raw:    "<mailto:listmom@host.com> (Contact Person for Help)",
+			urls: []*url.URL{
+				{Scheme: "mailto", Opaque: "listmom@host.com"},
+			},
+		},
+		{
+			header: "List-Owner",
+			raw:    "<mailto:grant@foo.bar> (Grant Neufeld)",
+			urls: []*url.URL{
+				{Scheme: "mailto", Opaque: "grant@foo.bar"},
+			},
+		},
+		{
+			header: "List-Owner",
+			raw:    "<mailto:josh@foo.bar?Subject=list>",
+			urls: []*url.URL{
+				{Scheme: "mailto", Opaque: "josh@foo.bar", RawQuery: "Subject=list"},
+			},
+		},
+		{
+			header: "List-Archive",
+			raw:    "<mailto:archive@host.com?subject=index%20list>",
+			urls: []*url.URL{
+				{Scheme: "mailto", Opaque: "archive@host.com", RawQuery: "subject=index%20list"},
+			},
+		},
+		{
+			header: "List-Archive",
+			raw:    "<ftp://ftp.host.com/pub/list/archive/>",
+			urls: []*url.URL{
+				{Scheme: "ftp", Host: "ftp.host.com", Path: "/pub/list/archive/"},
+			},
+		},
+		{
+			header: "List-Archive",
+			raw:    "<http://www.host.com/list/archive/> (Web Archive)",
+			urls: []*url.URL{
+				{Scheme: "http", Host: "www.host.com", Path: "/list/archive/"},
+			},
+		},
+	}
+
+	for _, test := range tests {
+		var h mail.Header
+		h.Set(test.header, test.raw)
+
+		urls, err := h.ListCommandURLList(test.header)
+		if err != nil && !test.xfail {
+			t.Errorf("Failed to parse %s %q: Header.ListCommandURLList() = %v", test.header, test.raw, err)
+		} else if !reflect.DeepEqual(urls, test.urls) {
+			t.Errorf("Failed to parse %s %q: Header.ListCommandURLList() = %q, want %q", test.header, test.raw, urls, test.urls)
+		}
+	}
+}
+
+func TestHeader_SetListCommandURLList(t *testing.T) {
+	tests := []struct {
+		raw  string
+		urls []*url.URL
+	}{
+		{
+			raw: "<mailto:list@example.com>",
+			urls: []*url.URL{
+				{Scheme: "mailto", Opaque: "list@example.com"},
+			},
+		},
+		{
+			raw: "<mailto:list@example.com>, <https://example.com:8080>",
+			urls: []*url.URL{
+				{Scheme: "mailto", Opaque: "list@example.com"},
+				{Scheme: "https", Host: "example.com:8080"},
+			},
+		},
+	}
+	for _, test := range tests {
+		var h mail.Header
+		h.SetListCommandURLList("List-Post", test.urls)
+		raw := h.Get("List-Post")
+		if raw != test.raw {
+			t.Errorf("Failed to format List-Post %q: Header.Get() = %q, want %q", test.urls, raw, test.raw)
+		}
+	}
+}