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parser.go
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parser.go
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// Copyright 2017 syzkaller project authors. All rights reserved.
// Use of this source code is governed by Apache 2 LICENSE that can be found in the LICENSE file.
package email
import (
"encoding/base64"
"fmt"
"io"
"mime"
"mime/multipart"
"mime/quotedprintable"
"net/mail"
"regexp"
"sort"
"strings"
"time"
"unicode"
)
type Email struct {
BugIDs []string
MessageID string
InReplyTo string
Date time.Time
Link string
Subject string
MailingList string
Author string
OwnEmail bool
Cc []string
Body string // text/plain part
Patch string // attached patch, if any
Commands []*SingleCommand
}
type SingleCommand struct {
Command Command
Str string // string representation
Args string // arguments for the command
}
type Command int
const (
CmdUnknown Command = iota
CmdUpstream
CmdFix
CmdUnFix
CmdDup
CmdUnDup
CmdTest
CmdInvalid
CmdUnCC
CmdSet
CmdUnset
CmdRegenerate
cmdTest5
)
var groupsLinkRe = regexp.MustCompile("\nTo view this discussion on the web visit" +
" (https://groups\\.google\\.com/.*?)\\.(?:\r)?\n")
func prepareEmails(list []string) map[string]bool {
ret := make(map[string]bool)
for _, email := range list {
ret[email] = true
if addr, err := mail.ParseAddress(email); err == nil {
ret[addr.Address] = true
}
}
return ret
}
func Parse(r io.Reader, ownEmails, goodLists, domains []string) (*Email, error) {
msg, err := mail.ReadMessage(r)
if err != nil {
return nil, fmt.Errorf("failed to read email: %w", err)
}
from, err := msg.Header.AddressList("From")
if err != nil {
return nil, fmt.Errorf("failed to parse email header 'From': %w", err)
}
if len(from) == 0 {
return nil, fmt.Errorf("failed to parse email header 'To': no senders")
}
// Ignore errors since To: header may not be present (we've seen such case).
to, _ := msg.Header.AddressList("To")
// AddressList fails if the header is not present.
cc, _ := msg.Header.AddressList("Cc")
var ccList []string
ownAddrs := prepareEmails(ownEmails)
fromMe := false
for _, addr := range from {
cleaned, _, _ := RemoveAddrContext(addr.Address)
if addr, err := mail.ParseAddress(cleaned); err == nil && ownAddrs[addr.Address] {
fromMe = true
}
}
originalFrom := ""
// Ignore error since the header might not be present.
originalFroms, _ := msg.Header.AddressList("X-Original-From")
if len(originalFroms) > 0 {
originalFrom = originalFroms[0].String()
}
bugIDs := []string{}
rawCcList := append(append(append(cc, to...), from...), originalFroms...)
for _, addr := range rawCcList {
cleaned, context, _ := RemoveAddrContext(addr.Address)
if addr, err := mail.ParseAddress(cleaned); err == nil {
cleaned = addr.Address
}
if ownAddrs[cleaned] {
bugIDs = append(bugIDs, context)
} else {
ccList = append(ccList, CanonicalEmail(cleaned))
}
}
ccList = MergeEmailLists(ccList)
sender := ""
// Ignore error since the header might not be present.
senders, _ := msg.Header.AddressList("Sender")
if len(senders) > 0 {
sender = senders[0].Address
}
body, attachments, err := parseBody(msg.Body, msg.Header)
if err != nil {
return nil, err
}
bodyStr := string(body)
subject := msg.Header.Get("Subject")
var cmds []*SingleCommand
var patch string
if !fromMe {
for _, a := range attachments {
patch = ParsePatch(a)
if patch != "" {
break
}
}
if patch == "" {
patch = ParsePatch(body)
}
cmds = extractCommands(subject + "\n" + bodyStr)
}
bugIDs = append(bugIDs, extractBodyBugIDs(bodyStr, ownAddrs, domains)...)
link := ""
if match := groupsLinkRe.FindStringSubmatchIndex(bodyStr); match != nil {
link = bodyStr[match[2]:match[3]]
}
author := CanonicalEmail(from[0].Address)
mailingList := ""
goodListsMap := prepareEmails(goodLists)
if goodListsMap[author] {
// In some cases, the mailing list would change From and introduce X-Original-From.
mailingList = author
if originalFrom != "" {
author = CanonicalEmail(originalFrom)
}
// Not sure if `else` can happen here, but let it be mailingList == author in this case.
} else if goodListsMap[CanonicalEmail(sender)] {
// In other cases, the mailing list would preserve From and just change Sender.
mailingList = CanonicalEmail(sender)
}
date, _ := mail.ParseDate(msg.Header.Get("Date"))
email := &Email{
BugIDs: dedupBugIDs(bugIDs),
MessageID: msg.Header.Get("Message-ID"),
InReplyTo: extractInReplyTo(msg.Header),
Date: date,
Link: link,
Author: author,
OwnEmail: fromMe,
MailingList: mailingList,
Subject: subject,
Cc: ccList,
Body: bodyStr,
Patch: patch,
Commands: cmds,
}
return email, nil
}
// AddAddrContext embeds context into local part of the provided email address using '+'.
// Returns the resulting email address.
func AddAddrContext(email, context string) (string, error) {
addr, err := mail.ParseAddress(email)
if err != nil {
return "", fmt.Errorf("failed to parse %q as email: %w", email, err)
}
at := strings.IndexByte(addr.Address, '@')
if at == -1 {
return "", fmt.Errorf("failed to parse %q as email: no @", email)
}
result := addr.Address[:at] + "+" + context + addr.Address[at:]
if addr.Name != "" {
addr.Address = result
result = addr.String()
}
return result, nil
}
// RemoveAddrContext extracts context after '+' from the local part of the provided email address.
// Returns address without the context and the context.
func RemoveAddrContext(email string) (string, string, error) {
addr, err := mail.ParseAddress(email)
if err != nil {
return "", "", fmt.Errorf("failed to parse %q as email: %w", email, err)
}
at := strings.IndexByte(addr.Address, '@')
if at == -1 {
return "", "", fmt.Errorf("failed to parse %q as email: no @", email)
}
plus := strings.LastIndexByte(addr.Address[:at], '+')
if plus == -1 {
return email, "", nil
}
context := addr.Address[plus+1 : at]
addr.Address = addr.Address[:plus] + addr.Address[at:]
return addr.String(), context, nil
}
func CanonicalEmail(email string) string {
addr, err := mail.ParseAddress(email)
if err != nil {
return email
}
at := strings.IndexByte(addr.Address, '@')
if at == -1 {
return email
}
if plus := strings.IndexByte(addr.Address[:at], '+'); plus != -1 {
addr.Address = addr.Address[:plus] + addr.Address[at:]
}
return strings.ToLower(addr.Address)
}
func extractCommands(body string) []*SingleCommand {
var ret []*SingleCommand
for body != "" {
cmd, end := extractCommand(body)
if cmd == nil {
break
}
ret = append(ret, cmd)
body = body[end:]
}
return ret
}
const commandPrefix = "#syz"
var commandStartRe = regexp.MustCompile(`(?:^|\n)(` + regexp.QuoteMeta(commandPrefix) + `[ \t-:])`)
// extractCommand extracts command to syzbot from email body.
// Commands are of the following form:
// ^#syz cmd args...
func extractCommand(body string) (*SingleCommand, int) {
var cmd Command
var str, args string
match := commandStartRe.FindStringSubmatchIndex(body)
if match == nil {
return nil, 0
}
cmdPos := match[2] + len(commandPrefix) + 1
for cmdPos < len(body) && unicode.IsSpace(rune(body[cmdPos])) {
cmdPos++
}
cmdEnd := strings.IndexByte(body[cmdPos:], '\n')
if cmdEnd == -1 {
cmdEnd = len(body) - cmdPos
}
if cmdEnd1 := strings.IndexByte(body[cmdPos:], '\r'); cmdEnd1 != -1 && cmdEnd1 < cmdEnd {
cmdEnd = cmdEnd1
}
if cmdEnd1 := strings.IndexByte(body[cmdPos:], ' '); cmdEnd1 != -1 && cmdEnd1 < cmdEnd {
cmdEnd = cmdEnd1
}
if cmdEnd1 := strings.IndexByte(body[cmdPos:], '\t'); cmdEnd1 != -1 && cmdEnd1 < cmdEnd {
cmdEnd = cmdEnd1
}
str = body[cmdPos : cmdPos+cmdEnd]
cmd = strToCmd(str)
// Some email clients split text emails at 80 columns are the transformation is irrevesible.
// We try hard to restore what was there before.
// For "test:" command we know that there must be 2 tokens without spaces.
// For "fix:"/"dup:" we need a whole non-empty line of text.
switch cmd {
case CmdTest:
if strings.HasSuffix(str, ":") {
// For "#syz test:", we do want to query 2 arguments.
args = extractArgsTokens(body[cmdPos+cmdEnd:], 2)
} else {
// For "#syz test", it's likely there won't be anything else, so let's only parse
// the first line.
fmt.Printf("line: %s", body[cmdPos+cmdEnd:])
args = extractArgsLine(body[cmdPos+cmdEnd:], false)
}
case CmdSet, CmdUnset:
args = extractArgsLine(body[cmdPos+cmdEnd:], true)
case cmdTest5:
args = extractArgsTokens(body[cmdPos+cmdEnd:], 5)
case CmdFix, CmdDup:
args = extractArgsLine(body[cmdPos+cmdEnd:], true)
}
return &SingleCommand{
Command: cmd,
Str: str,
Args: args,
}, cmdPos + cmdEnd
}
func strToCmd(str string) Command {
switch str {
default:
return CmdUnknown
case "upstream":
return CmdUpstream
case "fix", "fix:":
return CmdFix
case "unfix":
return CmdUnFix
case "dup", "dup:":
return CmdDup
case "undup":
return CmdUnDup
case "test", "test:":
return CmdTest
case "invalid":
return CmdInvalid
case "uncc", "uncc:":
return CmdUnCC
case "set", "set:":
return CmdSet
case "unset", "unset:":
return CmdUnset
case "regenerate":
return CmdRegenerate
case "test_5_arg_cmd":
return cmdTest5
}
}
func extractArgsTokens(body string, num int) string {
var args []string
for pos := 0; len(args) < num && pos < len(body); {
lineEnd := strings.IndexByte(body[pos:], '\n')
if lineEnd == -1 {
lineEnd = len(body) - pos
}
line := strings.TrimSpace(strings.Replace(body[pos:pos+lineEnd], "\t", " ", -1))
for {
line1 := strings.Replace(line, " ", " ", -1)
if line == line1 {
break
}
line = line1
}
if line != "" {
args = append(args, strings.Split(line, " ")...)
}
pos += lineEnd + 1
}
return strings.TrimSpace(strings.Join(args, " "))
}
func extractArgsLine(body string, skipWs bool) string {
pos := 0
if skipWs {
for pos < len(body) && unicode.IsSpace(rune(body[pos])) {
pos++
}
}
lineEnd := strings.IndexByte(body[pos:], '\n')
if lineEnd == -1 {
lineEnd = len(body) - pos
}
return strings.TrimSpace(body[pos : pos+lineEnd])
}
func parseBody(r io.Reader, headers mail.Header) ([]byte, [][]byte, error) {
// git-send-email sends emails without Content-Type, let's assume it's text.
mediaType := "text/plain"
var params map[string]string
if contentType := headers.Get("Content-Type"); contentType != "" {
var err error
mediaType, params, err = mime.ParseMediaType(headers.Get("Content-Type"))
if err != nil {
return nil, nil, fmt.Errorf("failed to parse email header 'Content-Type': %w", err)
}
}
switch strings.ToLower(headers.Get("Content-Transfer-Encoding")) {
case "quoted-printable":
r = quotedprintable.NewReader(r)
case "base64":
r = base64.NewDecoder(base64.StdEncoding, r)
}
disp, _, _ := mime.ParseMediaType(headers.Get("Content-Disposition"))
if disp == "attachment" {
attachment, err := io.ReadAll(r)
if err != nil {
return nil, nil, fmt.Errorf("failed to read email body: %w", err)
}
return nil, [][]byte{attachment}, nil
}
if mediaType == "text/plain" {
body, err := io.ReadAll(r)
if err != nil {
return nil, nil, fmt.Errorf("failed to read email body: %w", err)
}
return body, nil, nil
}
if !strings.HasPrefix(mediaType, "multipart/") {
return nil, nil, nil
}
var body []byte
var attachments [][]byte
mr := multipart.NewReader(r, params["boundary"])
for {
p, err := mr.NextPart()
if err == io.EOF {
return body, attachments, nil
}
if err != nil {
return nil, nil, fmt.Errorf("failed to parse MIME parts: %w", err)
}
body1, attachments1, err1 := parseBody(p, mail.Header(p.Header))
if err1 != nil {
return nil, nil, err1
}
if body == nil {
body = body1
}
attachments = append(attachments, attachments1...)
}
}
var extractMessageIDs = regexp.MustCompile(`<.+?>`)
func extractInReplyTo(header mail.Header) string {
value := header.Get("In-Reply-To")
// Normally there should be just one message, to which we reply.
// However, there have been some cases when multiple addresses were mentioned.
// For now let's just take the first one.
ret := extractMessageIDs.FindStringSubmatch(value)
if ret != nil {
return ret[0]
}
return ""
}
func extractBodyBugIDs(body string, ownEmailMap map[string]bool, domains []string) []string {
// Let's build a regular expression.
var rb strings.Builder
for email := range ownEmailMap {
escaped := regexp.QuoteMeta(email)
part := strings.ReplaceAll(escaped, `@`, `\+(\w+?)@`)
if rb.Len() > 0 {
rb.WriteString(`|`)
}
rb.WriteString(part)
}
for _, domain := range domains {
escaped := regexp.QuoteMeta(domain + "/bug?extid=")
if rb.Len() > 0 {
rb.WriteString(`|`)
}
rb.WriteString(escaped)
rb.WriteString(`([\w]+)`)
}
rg := regexp.MustCompile(rb.String())
ids := []string{}
for _, match := range rg.FindAllStringSubmatch(body, -1) {
// Take all non-empty group matches.
for i := 1; i < len(match); i++ {
if match[i] == "" {
continue
}
ids = append(ids, match[i])
}
}
return ids
}
func dedupBugIDs(list []string) []string {
// We should preserve the original order of IDs.
var ret []string
dup := map[string]struct{}{}
for _, v := range list {
if _, ok := dup[v]; ok {
continue
}
dup[v] = struct{}{}
ret = append(ret, v)
}
return ret
}
// MergeEmailLists merges several email lists removing duplicates and invalid entries.
func MergeEmailLists(lists ...[]string) []string {
const (
maxEmailLen = 1000
maxEmails = 50
)
merged := make(map[string]bool)
for _, list := range lists {
for _, email := range list {
addr, err := mail.ParseAddress(email)
if err != nil || len(addr.Address) > maxEmailLen {
continue
}
merged[addr.Address] = true
}
}
var result []string
for e := range merged {
result = append(result, e)
}
sort.Strings(result)
if len(result) > maxEmails {
result = result[:maxEmails]
}
return result
}
func RemoveFromEmailList(list []string, toRemove string) []string {
var result []string
toRemove = CanonicalEmail(toRemove)
for _, email := range list {
if CanonicalEmail(email) != toRemove {
result = append(result, email)
}
}
return result
}