ergo/irc/utils/text.go

// Copyright (c) 2017 Daniel Oaks <daniel@danieloaks.net>
// released under the MIT license

package utils

import (
	"crypto/sha256"
	"encoding/json"
	"fmt"
	"github.com/cshum/imagor/imagorpath"
	"github.com/ergochat/irc-go/ircmsg"
	"net/http"
	"os"
	"regexp"
	"strings"
	"time"
)

func IsRestrictedCTCPMessage(message string) bool {
	// block all CTCP privmsgs to Tor clients except for ACTION
	// DCC can potentially be used for deanonymization, the others for fingerprinting
	return strings.HasPrefix(message, "\x01") && !strings.HasPrefix(message, "\x01ACTION")
}

type MessagePair struct {
	Message string
	Tags    map[string]string
	Concat  bool // should be relayed with the multiline-concat tag
}

// SplitMessage represents a message that's been split for sending.
// Two possibilities:
// (a) Standard message that can be relayed on a single 512-byte line
//
//	(MessagePair contains the message, Split == nil)
//
// (b) multiline message that was split on the client side
//
//	(Message == "", Split contains the split lines)
type SplitMessage struct {
	Message string
	Msgid   string
	Split   []MessagePair
	Time    time.Time
}

func MakeMessage(original string) (result SplitMessage) {
	result.Message = original
	result.Msgid = GenerateMessageIdStr()
	result.SetTime()

	return
}

func (sm *SplitMessage) Append(message string, concat bool, tags map[string]string) {
	if sm.Msgid == "" {
		sm.Msgid = GenerateMessageIdStr()
	}
	sm.Split = append(sm.Split, MessagePair{
		Message: message,
		Concat:  concat,
		Tags:    tags,
	})
}

func (sm *SplitMessage) SetTime() {
	// strip the monotonic time, it's a potential source of problems:
	sm.Time = time.Now().UTC().Round(0)
}

func (sm *SplitMessage) LenLines() int {
	if sm.Split == nil {
		if sm.Message == "" {
			return 0
		} else {
			return 1
		}
	}
	return len(sm.Split)
}

func (sm *SplitMessage) ValidMultiline() bool {
	// must contain at least one nonblank line
	for i := 0; i < len(sm.Split); i++ {
		if len(sm.Split[i].Message) != 0 {
			return true
		}
	}
	return false
}

func (sm *SplitMessage) IsRestrictedCTCPMessage() bool {
	if IsRestrictedCTCPMessage(sm.Message) {
		return true
	}
	for i := 0; i < len(sm.Split); i++ {
		if IsRestrictedCTCPMessage(sm.Split[i].Message) {
			return true
		}
	}
	return false
}

func (sm *SplitMessage) Is512() bool {
	return sm.Split == nil
}

// TokenLineBuilder is a helper for building IRC lines composed of delimited tokens,
// with a maximum line length.
type TokenLineBuilder struct {
	lineLen int
	delim   string
	buf     strings.Builder
	result  []string
}

func (t *TokenLineBuilder) Initialize(lineLen int, delim string) {
	t.lineLen = lineLen
	t.delim = delim
}

// Add adds a token to the line, creating a new line if necessary.
func (t *TokenLineBuilder) Add(token string) {
	tokenLen := len(token)
	if t.buf.Len() != 0 {
		tokenLen += len(t.delim)
	}
	if t.lineLen < t.buf.Len()+tokenLen {
		t.result = append(t.result, t.buf.String())
		t.buf.Reset()
	}
	if t.buf.Len() != 0 {
		t.buf.WriteString(t.delim)
	}
	t.buf.WriteString(token)
}

// AddParts concatenates `parts` into a token and adds it to the line,
// creating a new line if necessary.
func (t *TokenLineBuilder) AddParts(parts ...string) {
	var tokenLen int
	for _, part := range parts {
		tokenLen += len(part)
	}
	if t.buf.Len() != 0 {
		tokenLen += len(t.delim)
	}
	if t.lineLen < t.buf.Len()+tokenLen {
		t.result = append(t.result, t.buf.String())
		t.buf.Reset()
	}
	if t.buf.Len() != 0 {
		t.buf.WriteString(t.delim)
	}
	for _, part := range parts {
		t.buf.WriteString(part)
	}
}

// Lines terminates the line-building and returns all the lines.
func (t *TokenLineBuilder) Lines() (result []string) {
	result = t.result
	t.result = nil
	if t.buf.Len() != 0 {
		result = append(result, t.buf.String())
		t.buf.Reset()
	}
	return
}

// BuildTokenLines is a convenience to apply TokenLineBuilder to a predetermined
// slice of tokens.
func BuildTokenLines(lineLen int, tokens []string, delim string) []string {
	var tl TokenLineBuilder
	tl.Initialize(lineLen, delim)
	for _, arg := range tokens {
		tl.Add(arg)
	}
	return tl.Lines()
}

var urlRegex = regexp.MustCompile("https?:\\/\\/[\\w-]+(\\.[\\w-]+)+([\\w.,@?^=%&amp;:/~+#-]*[\\w@?^=%&amp;/~+#-])?")

func GenerateImagorSignaturesFromMessage(message *ircmsg.Message) string {
	line, err := message.Line()
	if err == nil {
		return GenerateImagorSignatures(line)
	}
	return ""
}

var secretKey = os.Getenv("IMAGOR_SECRET")
var baseUrl = os.Getenv("IMAGOR_URL")

func GetUrlMime(url string) string {
	// hacky, should fix
	if !strings.Contains(url, "?") {
		url += "?"
	}
	params := imagorpath.Params{
		Image: url,
		Meta:  true,
	}
	metaPath := imagorpath.Generate(params, imagorpath.NewHMACSigner(sha256.New, 0, secretKey))
	client := http.Client{
		Timeout: 5 * time.Second,
	}
	resp, err := client.Get(baseUrl + metaPath)
	if err != nil {
		println("Failed on the initial get")
		println(err.Error())
		return ""
	}
	defer resp.Body.Close()
	var meta map[string]interface{}
	err = json.NewDecoder(resp.Body).Decode(&meta)
	if err != nil {
		println("Failed on the JSON decode")
		return ""
	}
	contentType, valid := meta["format"].(string)
	fmt.Printf("%+v\n", meta)
	if !valid {
		println("No content type")
		return ""
	}
	return contentType
}

// Process a message to add Imagor signatures
func GenerateImagorSignatures(str string) string {
	urls := urlRegex.FindAllString(str, -1)
	var sigs []string
	for _, url := range urls {
		params := imagorpath.Params{
			Image:  url,
			FitIn:  true,
			Width:  600,
			Height: 600,
		}
		path := imagorpath.Generate(params, imagorpath.NewHMACSigner(sha256.New, 0, secretKey))
		signature := path[:strings.IndexByte(path, '/')]
		contentType := GetUrlMime(url)
		if contentType != "" {
			sigs = append(sigs, signature+"|"+strings.ReplaceAll(contentType, "/", "_"))
		} else {
			sigs = append(sigs, signature)
		}

	}
	if len(sigs) > 0 {
		return strings.Join(sigs, ",")
	}
	return ""
}