Add support for markdown to HTML conversion (matrix). Closes #663 (#670)

This uses our own gomatrix lib with the SendHTML function which
adds HTML to formatted_body in matrix.
golang-commonmark is used to convert markdown into valid HTML.

vendor/gitlab.com/golang-commonmark/linkify/.gitlab-ci.yml

@@ -0,0 +1,19 @@
+image: golang:1.11
+
+stages:
+  - build
+  - test
+
+before_script:
+  - go get golang.org/x/text/unicode/rangetable
+
+build:
+  stage: build
+  script:
+    - go build ./...
+
+test:
+  stage: test
+  script:
+    - test -z "$(gofmt -l . | tee /dev/stderr)"
+    - go test ./...

vendor/gitlab.com/golang-commonmark/linkify/LICENSE

@@ -0,0 +1,10 @@
+Copyright (c) 2015, The Authors
+All rights reserved.
+
+Redistribution and use in source and binary forms, with or without modification, are permitted provided that the following conditions are met:
+
+1. Redistributions of source code must retain the above copyright notice, this list of conditions and the following disclaimer.
+
+2. Redistributions in binary form must reproduce the above copyright notice, this list of conditions and the following disclaimer in the documentation and/or other materials provided with the distribution.
+
+THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

vendor/gitlab.com/golang-commonmark/linkify/README.md

@@ -0,0 +1,12 @@
+linkify [![License](https://img.shields.io/badge/licence-BSD--2--Clause-blue.svg)](https://opensource.org/licenses/BSD-2-Clause) [![GoDoc](http://godoc.org/gitlab.com/golang-commonmark/linkify?status.svg)](http://godoc.org/gitlab.com/golang-commonmark/linkify) [![Pipeline status](https://gitlab.com/golang-commonmark/linkify/badges/master/pipeline.svg)](https://gitlab.com/golang-commonmark/linkify/commits/master)
+=======
+
+Package linkify provides a way to find what looks like links in plain text.
+
+## Install
+
+    go get -u gitlab.com/golang-commonmark/linkify
+
+## Use
+
+See an [example](https://gitlab.com/golang-commonmark/linkify/blob/master/linkify_example_test.go).

vendor/gitlab.com/golang-commonmark/linkify/charset.go

@@ -0,0 +1,51 @@
+// Copyright 2015 The Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package linkify
+
+import (
+	"unicode"
+
+	"golang.org/x/text/unicode/rangetable"
+)
+
+var (
+	unreserved = [256]bool{'-': true, '.': true, '_': true, '~': true}
+	basicPunct = [256]bool{'.': true, ',': true, '?': true, '!': true, ';': true, ':': true}
+	subdelims  = [256]bool{'!': true, '$': true, '&': true, '\'': true, '(': true, ')': true,
+		'*': true, '+': true, ',': true, ';': true, '=': true}
+	emailcs = [256]bool{'a': true, 'b': true, 'c': true, 'd': true, 'e': true, 'f': true, 'g': true,
+		'h': true, 'i': true, 'j': true, 'k': true, 'l': true, 'm': true, 'n': true, 'o': true,
+		'p': true, 'q': true, 'r': true, 's': true, 't': true, 'u': true, 'v': true, 'w': true,
+		'x': true, 'y': true, 'z': true, 'A': true, 'B': true, 'C': true, 'D': true, 'E': true,
+		'F': true, 'G': true, 'H': true, 'I': true, 'J': true, 'K': true, 'L': true, 'M': true,
+		'N': true, 'O': true, 'P': true, 'Q': true, 'R': true, 'S': true, 'T': true, 'U': true,
+		'V': true, 'W': true, 'X': true, 'Y': true, 'Z': true, '0': true, '1': true, '2': true,
+		'3': true, '4': true, '5': true, '6': true, '7': true, '8': true, '9': true, '!': true,
+		'#': true, '$': true, '%': true, '&': true, '\'': true, '*': true, '+': true, '/': true,
+		'=': true, '?': true, '^': true, '_': true, '`': true, '{': true, '|': true, '}': true,
+		'~': true, '-': true}
+	letterOrDigit = rangetable.Merge(unicode.Letter, unicode.Digit)
+	punctSpaceCc  = rangetable.Merge(unicode.Punct, unicode.Space, unicode.Cc)
+)
+
+func isAllowedInEmail(r rune) bool {
+	return r < 0x7f && emailcs[r]
+}
+
+func isLetterOrDigit(r rune) bool {
+	return unicode.Is(letterOrDigit, r)
+}
+
+func isPunctOrSpaceOrControl(r rune) bool {
+	return r == '<' || r == '>' || r == '\uff5c' || unicode.Is(punctSpaceCc, r)
+}
+
+func isUnreserved(r rune) bool {
+	return (r < 0x7f && unreserved[r]) || unicode.Is(letterOrDigit, r)
+}
+
+func isSubDelimiter(r rune) bool {
+	return r < 0x7f && subdelims[r]
+}

vendor/gitlab.com/golang-commonmark/linkify/email.go

@@ -0,0 +1,93 @@
+// Copyright 2015 The Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package linkify
+
+import (
+	"unicode"
+	"unicode/utf8"
+)
+
+func findEmailStart(s string, start int) (_ int, _ bool) {
+	end := start
+	allowDot := false
+	for end >= 0 {
+		b := s[end]
+		switch {
+		case emailcs[b]:
+			allowDot = true
+		case b == '.':
+			if !allowDot {
+				return
+			}
+			allowDot = false
+		default:
+			if end == start {
+				return
+			}
+			if s[end+1] == '.' {
+				return
+			}
+			r, _ := utf8.DecodeLastRuneInString(s[:end+1])
+			if r == utf8.RuneError {
+				return
+			}
+			if !unicode.IsSpace(r) {
+				return
+			}
+			return end + 1, true
+		}
+		end--
+	}
+	if end < start && s[end+1] == '.' {
+		return
+	}
+	return end + 1, true
+}
+
+func findEmailEnd(s string, start int) (_ int, _ bool) {
+	end := start
+	allowDot := false
+loop:
+	for end < len(s) {
+		b := s[end]
+		switch {
+		case emailcs[b]:
+			allowDot = true
+		case b == '.':
+			if !allowDot {
+				return
+			}
+			allowDot = false
+		case b == '@':
+			break loop
+		default:
+			return
+		}
+		end++
+	}
+	if end >= len(s)-5 {
+		return
+	}
+	if end > start && s[end-1] == '.' {
+		return
+	}
+
+	var dot int
+	var ok bool
+	end, dot, ok = findHostnameEnd(s, end+1)
+	if !ok || dot == -1 {
+		return
+	}
+
+	if dot+5 <= len(s) && s[dot+1:dot+5] == "xn--" {
+		return end, true
+	}
+
+	if length := match(s[dot+1:]); dot+length+1 != end {
+		return
+	}
+
+	return end, true
+}

vendor/gitlab.com/golang-commonmark/linkify/linkify.go

@@ -0,0 +1,462 @@
+// Copyright 2015 The Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// Package linkify provides a way to find links in plain text.
+package linkify
+
+import (
+	"strings"
+	"unicode/utf8"
+)
+
+// Link represents a link found in a string with a schema and a position in the string.
+type Link struct {
+	Scheme     string
+	Start, End int
+}
+
+func max(a, b int) int {
+	if a >= b {
+		return a
+	}
+	return b
+}
+
+// Links returns links found in s.
+func Links(s string) (links []Link) {
+	for i := 0; i < len(s)-2; i++ {
+		switch s[i] {
+		case '.': // IP address or domain name
+			if i == 0 {
+				continue // . at the start of a line
+			}
+			if length := match(s[i+1:]); length > 0 {
+				pos := i + 1 + length
+				switch s[pos-1] {
+				case '.': // IP address
+					if pos >= len(s) {
+						continue // . at the end of line
+					}
+					if !digit(s[i-1]) {
+						i = pos
+						continue // . should be preceded by a digit
+					}
+					if !digit(s[pos]) {
+						i = pos
+						continue // . should be followed by a digit
+					}
+
+					// find the start of the IP address
+					j := i - 2
+					m := max(0, j-3)
+					for j >= m && digit(s[j]) {
+						j--
+					}
+					if i-2-j > 2 {
+						i = pos + 1
+						continue // at most 3 digits
+					}
+					start := 0
+					if j >= 0 {
+						r, rlen := utf8.DecodeLastRuneInString(s[:j+1])
+						if !isPunctOrSpaceOrControl(r) {
+							i = pos + 1
+							continue
+						}
+						switch r {
+						case '.', ':', '/', '\\', '-', '_':
+							i = pos + 1
+							continue
+						}
+						start = j + 2 - rlen
+					}
+
+					length, ok := skipIPv4(s[start:])
+					if !ok {
+						i = pos + 1
+						continue
+					}
+					end := start + length
+					if end == len(s) {
+						links = append(links, Link{
+							Scheme: "",
+							Start:  start,
+							End:    end,
+						})
+						return
+					}
+
+					r, _ := utf8.DecodeRuneInString(s[end:])
+					if !isPunctOrSpaceOrControl(r) {
+						continue
+					}
+
+					end = skipPort(s, end)
+					end = skipPath(s, end)
+					end = skipQuery(s, end)
+					end = skipFragment(s, end)
+					end = unskipPunct(s, end)
+
+					if end < len(s) {
+						r, _ = utf8.DecodeRuneInString(s[end:])
+						if !isPunctOrSpaceOrControl(r) || r == '%' {
+							continue
+						}
+					}
+
+					links = append(links, Link{
+						Scheme: "",
+						Start:  start,
+						End:    end,
+					})
+					i = end
+
+				default: // domain name
+					r, _ := utf8.DecodeLastRuneInString(s[:i])
+					if isPunctOrSpaceOrControl(r) {
+						continue
+					}
+
+					if pos == len(s) {
+						start, ok := findHostnameStart(s, i)
+						if !ok {
+							continue
+						}
+						links = append(links, Link{
+							Scheme: "",
+							Start:  start,
+							End:    pos,
+						})
+						return
+					}
+
+					if s[i+1:pos] != "xn--" {
+						r, _ = utf8.DecodeRuneInString(s[pos:])
+						if isLetterOrDigit(r) {
+							continue // should not be followed by a letter or a digit
+						}
+					}
+
+					end, dot, ok := findHostnameEnd(s, pos)
+					if !ok {
+						continue
+					}
+					dot = max(dot, i)
+
+					if !(dot+5 <= len(s) && s[dot+1:dot+5] == "xn--") {
+						if length := match(s[dot+1:]); dot+length+1 != end {
+							continue
+						}
+					}
+
+					start, ok := findHostnameStart(s, i)
+					if !ok {
+						continue
+					}
+
+					end = skipPort(s, end)
+					end = skipPath(s, end)
+					end = skipQuery(s, end)
+					end = skipFragment(s, end)
+					end = unskipPunct(s, end)
+
+					if end < len(s) {
+						r, _ = utf8.DecodeRuneInString(s[end:])
+						if !isPunctOrSpaceOrControl(r) || r == '%' {
+							continue // should be followed by punctuation or space
+						}
+					}
+
+					links = append(links, Link{
+						Scheme: "",
+						Start:  start,
+						End:    end,
+					})
+					i = end
+				}
+			}
+
+		case '/': // schema-less link
+			if s[i+1] != '/' {
+				continue
+			}
+
+			if i > 0 {
+				if s[i-1] == ':' {
+					i++
+					continue // should not be preceded by a colon
+				}
+				r, _ := utf8.DecodeLastRuneInString(s[:i])
+				if !isPunctOrSpaceOrControl(r) {
+					i++
+					continue // should be preceded by punctuation or space
+				}
+			}
+
+			r, _ := utf8.DecodeRuneInString(s[i+2:])
+			if !isLetterOrDigit(r) {
+				i++
+				continue // should be followed by a letter or a digit
+			}
+
+			start := i
+			end, dot, ok := findHostnameEnd(s, i+2)
+			if !ok {
+				continue
+			}
+			if s[i+2:end] != "localhost" {
+				if dot == -1 {
+					continue // no dot
+				}
+				if length, ok := skipIPv4(s[i+2:]); !ok || i+2+length != end {
+					if length := match(s[dot+1:]); dot+length+1 != end {
+						continue
+					}
+				}
+			}
+
+			end = skipPort(s, end)
+			end = skipPath(s, end)
+			end = skipQuery(s, end)
+			end = skipFragment(s, end)
+			end = unskipPunct(s, end)
+
+			if end < len(s) {
+				r, _ = utf8.DecodeRuneInString(s[end:])
+				if !isPunctOrSpaceOrControl(r) || r == '%' {
+					continue // should be followed by punctuation or space
+				}
+			}
+
+			links = append(links, Link{
+				Scheme: "//",
+				Start:  start,
+				End:    end,
+			})
+			i = end
+
+		case ':': // http, https, ftp, mailto or localhost
+			if i < 3 { // at least ftp:
+				continue
+			}
+
+			if i >= 9 && s[i-1] == 't' && s[i-9:i] == "localhost" {
+				j := i - 9
+				if !digit(s[j+10]) {
+					continue
+				}
+				if j > 0 {
+					r, _ := utf8.DecodeLastRuneInString(s[:j])
+					if !isPunctOrSpaceOrControl(r) {
+						i++
+						continue // should be preceded by punctuation or space
+					}
+				}
+
+				start := j
+				pos := j + 9
+				end := skipPort(s, pos)
+				if end == pos {
+					continue // invalid port
+				}
+				end = skipPath(s, end)
+				end = skipQuery(s, end)
+				end = skipFragment(s, end)
+				end = unskipPunct(s, end)
+
+				if end < len(s) {
+					r, _ := utf8.DecodeRuneInString(s[end:])
+					if !isPunctOrSpaceOrControl(r) || r == '%' {
+						i++
+						continue // should be followed by punctuation or space
+					}
+				}
+
+				links = append(links, Link{
+					Scheme: "",
+					Start:  start,
+					End:    end,
+				})
+				i = end
+
+				break
+			}
+
+			j := i - 1
+			var start int
+			var schema string
+
+			switch byteToLower(s[j]) {
+			case 'o': // mailto
+				if j < 5 {
+					continue // too short for mailto
+				}
+				if len(s)-j < 8 {
+					continue // insufficient length after
+				}
+				if strings.ToLower(s[j-5:j+2]) != "mailto:" {
+					continue
+				}
+				r, _ := utf8.DecodeLastRuneInString(s[:j-5])
+				if isLetterOrDigit(r) {
+					continue // should not be preceded by a letter or a digit
+				}
+				r, _ = utf8.DecodeRuneInString(s[j+2:])
+				if !isAllowedInEmail(r) {
+					continue // should be followed by a valid e-mail character
+				}
+
+				start = j - 5
+				end, ok := findEmailEnd(s, j+2)
+				if !ok {
+					continue
+				}
+
+				links = append(links, Link{
+					Scheme: "mailto:",
+					Start:  start,
+					End:    end,
+				})
+				i = end
+				continue // continue processing
+
+			case 'p': // http or ftp
+				if len(s)-j < 8 {
+					continue // insufficient length after
+				}
+				switch byteToLower(s[j-2]) {
+				case 'f':
+					if strings.ToLower(s[j-2:j+4]) != "ftp://" {
+						continue
+					}
+					start = j - 2
+					schema = "ftp:"
+				case 't':
+					if j < 3 {
+						continue
+					}
+					if strings.ToLower(s[j-3:j+4]) != "http://" {
+						continue
+					}
+					start = j - 3
+					schema = "http:"
+				default:
+					continue
+				}
+
+			case 's': // https
+				if j < 4 {
+					continue // too short for https
+				}
+				if len(s)-j < 8 {
+					continue // insufficient length after
+				}
+				start = j - 4
+				if strings.ToLower(s[start:j+4]) != "https://" {
+					continue
+				}
+				schema = "https:"
+
+			default:
+				continue
+			}
+
+			// http, https or ftp
+
+			if start > 0 {
+				r, _ := utf8.DecodeLastRuneInString(s[:start])
+				if !isPunctOrSpaceOrControl(r) {
+					continue // should be preceded by punctuation or space
+				}
+			}
+
+			r, _ := utf8.DecodeRuneInString(s[j+4:])
+			if isPunctOrSpaceOrControl(r) {
+				continue
+			}
+
+			end, dot, ok := findHostnameEnd(s, j+4)
+			if !ok {
+				continue
+			}
+			if s[j+4:end] != "localhost" {
+				if dot == -1 {
+					continue // no dot
+				}
+				if length, ok := skipIPv4(s[j+4:]); !ok || j+4+length != end {
+					if !(dot+5 <= len(s) && s[dot+1:dot+5] == "xn--") {
+						if length := match(s[dot+1:]); dot+length+1 != end {
+							continue
+						}
+					}
+				}
+			}
+
+			end = skipPort(s, end)
+			end = skipPath(s, end)
+			end = skipQuery(s, end)
+			end = skipFragment(s, end)
+			end = unskipPunct(s, end)
+
+			if end < len(s) {
+				r, _ = utf8.DecodeRuneInString(s[end:])
+				if !isPunctOrSpaceOrControl(r) || r == '%' {
+					continue // should be followed by punctuation or space
+				}
+			}
+
+			links = append(links, Link{
+				Scheme: schema,
+				Start:  start,
+				End:    end,
+			})
+			i = end
+
+		case '@': // schema-less e-mail
+			if i == 0 {
+				continue // @ at the start of a line
+			}
+
+			if len(s)-i < 5 {
+				continue // insufficient length after
+			}
+
+			r, _ := utf8.DecodeLastRuneInString(s[:i])
+			if !isAllowedInEmail(r) {
+				continue // should be preceded by a valid e-mail character
+			}
+
+			r, _ = utf8.DecodeRuneInString(s[i+1:])
+			if !isLetterOrDigit(r) {
+				continue // should be followed by a letter or a digit
+			}
+
+			start, ok := findEmailStart(s, i-1)
+			if !ok {
+				continue
+			}
+
+			end, dot, ok := findHostnameEnd(s, i+1)
+			if !ok {
+				continue
+			}
+			if dot == -1 {
+				continue // no dot
+			}
+			if !(dot+5 <= len(s) && s[dot+1:dot+5] == "xn--") {
+				if length := match(s[dot+1:]); dot+length+1 != end {
+					continue
+				}
+			}
+
+			links = append(links, Link{
+				Scheme: "mailto:",
+				Start:  start,
+				End:    end,
+			})
+			i = end
+		}
+	}
+	return
+}

vendor/gitlab.com/golang-commonmark/linkify/url.go

@@ -0,0 +1,404 @@
+// Copyright 2015 The Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package linkify
+
+import "unicode/utf8"
+
+func atoi3(s string, start int) (int, bool) {
+	n := 0
+	var i int
+	for i = start; i < len(s) && digit(s[i]); i++ {
+		n = n*10 + int(s[i]-'0')
+		if n > 255 {
+			return 0, false
+		}
+	}
+	if i == start {
+		return 0, false
+	}
+	return i, true
+}
+
+func skipIPv4(s string) (_ int, _ bool) {
+	j := 0
+	for i := 0; i < 4; i++ {
+		if j >= len(s) {
+			return
+		}
+		if i > 0 {
+			if s[j] != '.' {
+				return
+			}
+			j++
+		}
+		n, ok := atoi3(s, j)
+		if !ok {
+			return
+		}
+		j = n
+	}
+	return j, true
+}
+
+func atoi5(s string, start int) (int, bool) {
+	n := 0
+	var i int
+	for i = start; i < len(s) && digit(s[i]); i++ {
+		n = n*10 + int(s[i]-'0')
+		if n > 65535 {
+			return 0, false
+		}
+	}
+	if i == start || n == 0 {
+		return 0, false
+	}
+	return i, true
+}
+
+func skipPort(s string, start int) int {
+	if start >= len(s) || s[start] != ':' {
+		return start
+	}
+	end, ok := atoi5(s, start+1)
+	if !ok {
+		return start
+	}
+	return end
+}
+
+func skipPath(s string, start int) int {
+	if start >= len(s) || s[start] != '/' {
+		return start // skip empty path
+	}
+	var stack []rune
+	var notClosedIndex int
+	var nHyphen int
+	end := start + 1
+loop:
+	for end < len(s) {
+		r, rlen := utf8.DecodeRuneInString(s[end:])
+		if r == utf8.RuneError {
+			nHyphen = 0
+			break
+		}
+
+		switch {
+		case isUnreserved(r):
+			if r == '-' {
+				nHyphen++
+				if nHyphen > 1 {
+					break loop
+				}
+			} else {
+				nHyphen = 0
+			}
+		case isSubDelimiter(r) || r == '[' || r == ']':
+			nHyphen = 0
+			switch r {
+			case '[', '(':
+				if len(stack) == 0 {
+					notClosedIndex = end
+				}
+				stack = append(stack, r)
+			case ']', ')':
+				opening := '['
+				if r == ')' {
+					opening = '('
+				}
+				if len(stack) == 0 || stack[len(stack)-1] != opening {
+					break loop
+				}
+				stack = stack[:len(stack)-1]
+			}
+		case r == '/' || r == ':' || r == '@':
+			nHyphen = 0
+		case r == '%':
+			nHyphen = 0
+			if end+2 >= len(s) {
+				break loop
+			}
+			if !(hexDigit(s[end+1]) &&
+				hexDigit(s[end+2])) {
+				break loop
+			}
+			end += 2
+		default:
+			nHyphen = 0
+			if r != ' ' || len(stack) == 0 {
+				break loop
+			}
+		}
+		end += rlen
+	}
+	if len(stack) > 0 {
+		return notClosedIndex
+	}
+	if nHyphen > 0 {
+		return end - nHyphen + 1
+	}
+	return end
+}
+
+func skipQuery(s string, start int) int {
+	if start >= len(s) || s[start] != '?' {
+		return start
+	}
+	var stack []rune
+	var notClosedIndex int
+	var nHyphen int
+	end := start + 1
+loop:
+	for end < len(s) {
+		r, rlen := utf8.DecodeRuneInString(s[end:])
+		if r == utf8.RuneError {
+			nHyphen = 0
+			break
+		}
+
+		switch {
+		case isUnreserved(r):
+			if r == '-' {
+				nHyphen++
+				if nHyphen > 1 {
+					break loop
+				}
+			} else {
+				nHyphen = 0
+			}
+		case isSubDelimiter(r) || r == '[' || r == ']':
+			nHyphen = 0
+			switch r {
+			case '[', '(':
+				if len(stack) == 0 {
+					notClosedIndex = end
+				}
+				stack = append(stack, r)
+			case ']', ')':
+				opening := '['
+				if r == ')' {
+					opening = '('
+				}
+				if len(stack) == 0 || stack[len(stack)-1] != opening {
+					break loop
+				}
+				stack = stack[:len(stack)-1]
+			}
+		case r == '?' || r == '/' || r == ':' || r == '@':
+			nHyphen = 0
+		case r == '%':
+			nHyphen = 0
+			if end+2 >= len(s) {
+				break loop
+			}
+			if !(hexDigit(s[end+1]) &&
+				hexDigit(s[end+2])) {
+				break loop
+			}
+			end += 2
+		default:
+			nHyphen = 0
+			if r != ' ' || len(stack) == 0 {
+				break loop
+			}
+		}
+		end += rlen
+	}
+	if len(stack) > 0 {
+		return notClosedIndex
+	}
+	if nHyphen > 0 {
+		return end - nHyphen + 1
+	}
+	return end
+}
+
+func skipFragment(s string, start int) int {
+	if start >= len(s) || s[start] != '#' {
+		return start
+	}
+	var stack []rune
+	var notClosedIndex int
+	var nHyphen int
+	end := start + 1
+loop:
+	for end < len(s) {
+		r, rlen := utf8.DecodeRuneInString(s[end:])
+		if r == utf8.RuneError {
+			nHyphen = 0
+			break
+		}
+
+		switch {
+		case isUnreserved(r):
+			if r == '-' {
+				nHyphen++
+				if nHyphen > 1 {
+					break loop
+				}
+			} else {
+				nHyphen = 0
+			}
+		case isSubDelimiter(r) || r == '[' || r == ']':
+			nHyphen = 0
+			switch r {
+			case '[', '(':
+				if len(stack) == 0 {
+					notClosedIndex = end
+				}
+				stack = append(stack, r)
+			case ']', ')':
+				opening := '['
+				if r == ')' {
+					opening = '('
+				}
+				if len(stack) == 0 || stack[len(stack)-1] != opening {
+					break loop
+				}
+				stack = stack[:len(stack)-1]
+			}
+		case r == '?' || r == '/' || r == ':' || r == '@':
+			nHyphen = 0
+		case r == '%':
+			nHyphen = 0
+			if end+2 >= len(s) {
+				break loop
+			}
+			if !(hexDigit(s[end+1]) &&
+				hexDigit(s[end+2])) {
+				break loop
+			}
+			end += 2
+		default:
+			nHyphen = 0
+			if r != ' ' || len(stack) == 0 {
+				break loop
+			}
+		}
+		end += rlen
+	}
+	if len(stack) > 0 {
+		return notClosedIndex
+	}
+	if nHyphen > 0 {
+		return end - nHyphen + 1
+	}
+	return end
+}
+
+func unskipPunct(s string, start int) int {
+	end := start - 1
+	if end < 0 || end >= len(s) || !basicPunct[s[end]] {
+		return start
+	}
+	return end
+}
+
+func findHostnameStart(s string, start int) (_ int, _ bool) {
+	end := start
+	lastDot := true
+	nHyphen := 0
+loop:
+	for end > 0 {
+		r, rlen := utf8.DecodeLastRuneInString(s[:end])
+		if r == utf8.RuneError {
+			return
+		}
+
+		switch {
+		case r == '.':
+			if nHyphen > 0 {
+				return
+			}
+			lastDot = true
+		case r == '-':
+			if end == start {
+				return
+			}
+			if lastDot {
+				return
+			}
+			nHyphen++
+			if nHyphen == 3 {
+				return
+			}
+		case r == ':' || r == '/' || r == '\\' || r == '_':
+			return
+		case isPunctOrSpaceOrControl(r):
+			break loop
+		default:
+			lastDot = false
+			nHyphen = 0
+		}
+		end -= rlen
+	}
+	if lastDot || nHyphen > 0 {
+		return
+	}
+	return end, true
+}
+
+func findHostnameEnd(s string, start int) (_ int, _ int, _ bool) {
+	end := start
+	lastDot := false
+	lastDotPos := -1
+	nHyphen := 0
+loop:
+	for end < len(s) {
+		r, rlen := utf8.DecodeRuneInString(s[end:])
+		if r == utf8.RuneError {
+			return
+		}
+
+		switch {
+		case r == '.':
+			if nHyphen > 0 {
+				return
+			}
+			if lastDot {
+				break loop
+			}
+			lastDot = true
+			lastDotPos = end
+			nHyphen = 0
+		case r == '-':
+			lastDot = false
+			if end == start {
+				return
+			}
+			if lastDot {
+				return
+			}
+			nHyphen++
+			if nHyphen == 3 {
+				break loop
+			}
+		case r == '\\' || r == '_':
+			return
+		case isPunctOrSpaceOrControl(r):
+			break loop
+		default:
+			lastDot = false
+			nHyphen = 0
+		}
+		end += rlen
+	}
+
+	if nHyphen > 0 {
+		end -= nHyphen
+	} else if lastDot {
+		if s[end-1] == '.' {
+			end--
+		}
+		lastDotPos = end - 1
+		for lastDotPos >= start && s[lastDotPos] != '.' {
+			lastDotPos--
+		}
+		if lastDotPos < start {
+			lastDotPos = -1
+		}
+	}
+
+	return end, lastDotPos, true
+}

vendor/gitlab.com/golang-commonmark/linkify/util.go

@@ -0,0 +1,20 @@
+// Copyright 2015 The Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package linkify
+
+func digit(b byte) bool {
+	return b >= '0' && b <= '9'
+}
+
+func hexDigit(b byte) bool {
+	return digit(b) || b >= 'a' && b <= 'f' || b >= 'A' && b <= 'F'
+}
+
+func byteToLower(b byte) byte {
+	if b >= 'A' && b <= 'Z' {
+		return b - 'A' + 'a'
+	}
+	return b
+}