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package otr3
import (
"bytes"
"fmt"
"strconv"
"strings"
)
type whitespaceState int
const (
whitespaceNotSent whitespaceState = iota
whitespaceSent
whitespaceRejected
)
func convertToWhitespace(v string) []byte {
result := make([]byte, 0, len(v)*8)
for _, v := range []byte(v) {
result = append(result, []byte(strings.Replace(strings.Replace(fmt.Sprintf("%08s", strconv.FormatInt(int64(v), 2)), "0", " ", -1), "1", "\t", -1))...)
}
return result
}
var (
// Maps to OTRL_MESSAGE_TAG_BASE
whitespaceTagHeader = convertToWhitespace("OT")
)
func genWhitespaceTag(p policies) []byte {
ret := whitespaceTagHeader
if p.has(allowV2) {
ret = append(ret, otrV2{}.whitespaceTag()...)
}
if p.has(allowV3) {
ret = append(ret, otrV3{}.whitespaceTag()...)
}
return ret
}
func (c *Conversation) appendWhitespaceTag(message []byte) []byte {
if !c.Policies.has(sendWhitespaceTag) || c.whitespaceState == whitespaceRejected {
return message
}
c.whitespaceState = whitespaceSent
return append(message, genWhitespaceTag(c.Policies)...)
}
// By the spec "this tag may occur anywhere in the message"
func extractWhitespaceTag(message ValidMessage) (plain MessagePlaintext, versions int) {
wsPos := bytes.Index(message, whitespaceTagHeader)
currentData := message[wsPos+len(whitespaceTagHeader):]
for {
aw, r, has := nextAllWhite(currentData)
if !has {
break
}
currentData = r
if bytes.Equal(aw, otrV3{}.whitespaceTag()) {
versions |= (1 << 3)
} else if bytes.Equal(aw, otrV2{}.whitespaceTag()) {
versions |= (1 << 2)
}
}
plain = makeCopy(append(message[:wsPos], currentData...))
return
}
func (c *Conversation) processWhitespaceTag(message ValidMessage) (plain MessagePlaintext, toSend []messageWithHeader, err error) {
plain, versions := extractWhitespaceTag(message)
if !c.Policies.has(whitespaceStartAKE) {
return
}
toSend, err = c.startAKEFromWhitespaceTag(versions)
return
}
func nextAllWhite(data []byte) (allwhite []byte, rest []byte, hasAllWhite bool) {
if len(data) < 8 {
return nil, data, false
}
for i := 0; i < 8; i++ {
if data[i] != ' ' && data[i] != '\t' {
return nil, data, false
}
}
return data[0:8], data[8:], true
}
func (c *Conversation) startAKEFromWhitespaceTag(versions int) (toSend []messageWithHeader, err error) {
if err = c.commitToVersionFrom(versions); err != nil {
return
}
ts, e := c.sendDHCommit()
toSend, err = c.potentialAuthError(compactMessagesWithHeader(ts), e)
return
}
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