1 files changed, 517 insertions, 0 deletions
diff --git a/modules/markup/html.go b/modules/markup/html.go
new file mode 100644
index 0000000000..9daf0b0c6c
--- /dev/null
+++ b/modules/markup/html.go
@@ -0,0 +1,517 @@
+// Copyright 2017 The Gitea Authors. All rights reserved.
+// Use of this source code is governed by a MIT-style
+// license that can be found in the LICENSE file.
+
+package markup
+
+import (
+	"bytes"
+	"fmt"
+	"io"
+	"net/url"
+	"path"
+	"path/filepath"
+	"regexp"
+	"strings"
+
+	"code.gitea.io/gitea/modules/base"
+	"code.gitea.io/gitea/modules/log"
+	"code.gitea.io/gitea/modules/setting"
+
+	"github.com/Unknwon/com"
+	"golang.org/x/net/html"
+)
+
+// Issue name styles
+const (
+	IssueNameStyleNumeric      = "numeric"
+	IssueNameStyleAlphanumeric = "alphanumeric"
+)
+
+var (
+	// NOTE: All below regex matching do not perform any extra validation.
+	// Thus a link is produced even if the linked entity does not exist.
+	// While fast, this is also incorrect and lead to false positives.
+	// TODO: fix invalid linking issue
+
+	// MentionPattern matches string that mentions someone, e.g. @Unknwon
+	MentionPattern = regexp.MustCompile(`(\s|^|\W)@[0-9a-zA-Z-_\.]+`)
+
+	// IssueNumericPattern matches string that references to a numeric issue, e.g. #1287
+	IssueNumericPattern = regexp.MustCompile(`( |^|\()#[0-9]+\b`)
+	// IssueAlphanumericPattern matches string that references to an alphanumeric issue, e.g. ABC-1234
+	IssueAlphanumericPattern = regexp.MustCompile(`( |^|\()[A-Z]{1,10}-[1-9][0-9]*\b`)
+	// CrossReferenceIssueNumericPattern matches string that references a numeric issue in a different repository
+	// e.g. gogits/gogs#12345
+	CrossReferenceIssueNumericPattern = regexp.MustCompile(`( |^)[0-9a-zA-Z]+/[0-9a-zA-Z]+#[0-9]+\b`)
+
+	// Sha1CurrentPattern matches string that represents a commit SHA, e.g. d8a994ef243349f321568f9e36d5c3f444b99cae
+	// Although SHA1 hashes are 40 chars long, the regex matches the hash from 7 to 40 chars in length
+	// so that abbreviated hash links can be used as well. This matches git and github useability.
+	Sha1CurrentPattern = regexp.MustCompile(`(?:^|\s|\()([0-9a-f]{7,40})\b`)
+
+	// ShortLinkPattern matches short but difficult to parse [[name|link|arg=test]] syntax
+	ShortLinkPattern = regexp.MustCompile(`(\[\[.*?\]\]\w*)`)
+
+	// AnySHA1Pattern allows to split url containing SHA into parts
+	AnySHA1Pattern = regexp.MustCompile(`(http\S*)://(\S+)/(\S+)/(\S+)/(\S+)/([0-9a-f]{40})(?:/?([^#\s]+)?(?:#(\S+))?)?`)
+
+	validLinksPattern = regexp.MustCompile(`^[a-z][\w-]+://`)
+)
+
+// regexp for full links to issues/pulls
+var issueFullPattern *regexp.Regexp
+
+// IsLink reports whether link fits valid format.
+func IsLink(link []byte) bool {
+	return isLink(link)
+}
+
+// isLink reports whether link fits valid format.
+func isLink(link []byte) bool {
+	return validLinksPattern.Match(link)
+}
+
+func getIssueFullPattern() *regexp.Regexp {
+	if issueFullPattern == nil {
+		appURL := setting.AppURL
+		if len(appURL) > 0 && appURL[len(appURL)-1] != '/' {
+			appURL += "/"
+		}
+		issueFullPattern = regexp.MustCompile(appURL +
+			`\w+/\w+/(?:issues|pulls)/((?:\w{1,10}-)?[1-9][0-9]*)([\?|#]\S+.(\S+)?)?\b`)
+	}
+	return issueFullPattern
+}
+
+// FindAllMentions matches mention patterns in given content
+// and returns a list of found user names without @ prefix.
+func FindAllMentions(content string) []string {
+	mentions := MentionPattern.FindAllString(content, -1)
+	for i := range mentions {
+		mentions[i] = mentions[i][strings.Index(mentions[i], "@")+1:] // Strip @ character
+	}
+	return mentions
+}
+
+// cutoutVerbosePrefix cutouts URL prefix including sub-path to
+// return a clean unified string of request URL path.
+func cutoutVerbosePrefix(prefix string) string {
+	if len(prefix) == 0 || prefix[0] != '/' {
+		return prefix
+	}
+	count := 0
+	for i := 0; i < len(prefix); i++ {
+		if prefix[i] == '/' {
+			count++
+		}
+		if count >= 3+setting.AppSubURLDepth {
+			return prefix[:i]
+		}
+	}
+	return prefix
+}
+
+// URLJoin joins url components, like path.Join, but preserving contents
+func URLJoin(base string, elems ...string) string {
+	u, err := url.Parse(base)
+	if err != nil {
+		log.Error(4, "URLJoin: Invalid base URL %s", base)
+		return ""
+	}
+	joinArgs := make([]string, 0, len(elems)+1)
+	joinArgs = append(joinArgs, u.Path)
+	joinArgs = append(joinArgs, elems...)
+	u.Path = path.Join(joinArgs...)
+	return u.String()
+}
+
+// RenderIssueIndexPattern renders issue indexes to corresponding links.
+func RenderIssueIndexPattern(rawBytes []byte, urlPrefix string, metas map[string]string) []byte {
+	urlPrefix = cutoutVerbosePrefix(urlPrefix)
+
+	pattern := IssueNumericPattern
+	if metas["style"] == IssueNameStyleAlphanumeric {
+		pattern = IssueAlphanumericPattern
+	}
+
+	ms := pattern.FindAll(rawBytes, -1)
+	for _, m := range ms {
+		if m[0] == ' ' || m[0] == '(' {
+			m = m[1:] // ignore leading space or opening parentheses
+		}
+		var link string
+		if metas == nil {
+			link = fmt.Sprintf(`<a href="%s">%s</a>`, URLJoin(urlPrefix, "issues", string(m[1:])), m)
+		} else {
+			// Support for external issue tracker
+			if metas["style"] == IssueNameStyleAlphanumeric {
+				metas["index"] = string(m)
+			} else {
+				metas["index"] = string(m[1:])
+			}
+			link = fmt.Sprintf(`<a href="%s">%s</a>`, com.Expand(metas["format"], metas), m)
+		}
+		rawBytes = bytes.Replace(rawBytes, m, []byte(link), 1)
+	}
+	return rawBytes
+}
+
+// IsSameDomain checks if given url string has the same hostname as current Gitea instance
+func IsSameDomain(s string) bool {
+	if strings.HasPrefix(s, "/") {
+		return true
+	}
+	if uapp, err := url.Parse(setting.AppURL); err == nil {
+		if u, err := url.Parse(s); err == nil {
+			return u.Host == uapp.Host
+		}
+		return false
+	}
+	return false
+}
+
+// renderFullSha1Pattern renders SHA containing URLs
+func renderFullSha1Pattern(rawBytes []byte, urlPrefix string) []byte {
+	ms := AnySHA1Pattern.FindAllSubmatch(rawBytes, -1)
+	for _, m := range ms {
+		all := m[0]
+		protocol := string(m[1])
+		paths := string(m[2])
+		path := protocol + "://" + paths
+		author := string(m[3])
+		repoName := string(m[4])
+		path = URLJoin(path, author, repoName)
+		ltype := "src"
+		itemType := m[5]
+		if IsSameDomain(paths) {
+			ltype = string(itemType)
+		} else if string(itemType) == "commit" {
+			ltype = "commit"
+		}
+		sha := m[6]
+		var subtree string
+		if len(m) > 7 && len(m[7]) > 0 {
+			subtree = string(m[7])
+		}
+		var line []byte
+		if len(m) > 8 && len(m[8]) > 0 {
+			line = m[8]
+		}
+		urlSuffix := ""
+		text := base.ShortSha(string(sha))
+		if subtree != "" {
+			urlSuffix = "/" + subtree
+			text += urlSuffix
+		}
+		if line != nil {
+			value := string(line)
+			urlSuffix += "#"
+			urlSuffix += value
+			text += " ("
+			text += value
+			text += ")"
+		}
+		rawBytes = bytes.Replace(rawBytes, all, []byte(fmt.Sprintf(
+			`<a href="%s">%s</a>`, URLJoin(path, ltype, string(sha))+urlSuffix, text)), -1)
+	}
+	return rawBytes
+}
+
+// RenderFullIssuePattern renders issues-like URLs
+func RenderFullIssuePattern(rawBytes []byte) []byte {
+	ms := getIssueFullPattern().FindAllSubmatch(rawBytes, -1)
+	for _, m := range ms {
+		all := m[0]
+		id := string(m[1])
+		text := "#" + id
+		// TODO if m[2] is not nil, then link is to a comment,
+		// and we should indicate that in the text somehow
+		rawBytes = bytes.Replace(rawBytes, all, []byte(fmt.Sprintf(
+			`<a href="%s">%s</a>`, string(all), text)), -1)
+	}
+	return rawBytes
+}
+
+func firstIndexOfByte(sl []byte, target byte) int {
+	for i := 0; i < len(sl); i++ {
+		if sl[i] == target {
+			return i
+		}
+	}
+	return -1
+}
+
+func lastIndexOfByte(sl []byte, target byte) int {
+	for i := len(sl) - 1; i >= 0; i-- {
+		if sl[i] == target {
+			return i
+		}
+	}
+	return -1
+}
+
+// RenderShortLinks processes [[syntax]]
+//
+// noLink flag disables making link tags when set to true
+// so this function just replaces the whole [[...]] with the content text
+//
+// isWikiMarkdown is a flag to choose linking url prefix
+func RenderShortLinks(rawBytes []byte, urlPrefix string, noLink bool, isWikiMarkdown bool) []byte {
+	ms := ShortLinkPattern.FindAll(rawBytes, -1)
+	for _, m := range ms {
+		orig := bytes.TrimSpace(m)
+		m = orig[2:]
+		tailPos := lastIndexOfByte(m, ']') + 1
+		tail := []byte{}
+		if tailPos < len(m) {
+			tail = m[tailPos:]
+			m = m[:tailPos-1]
+		}
+		m = m[:len(m)-2]
+		props := map[string]string{}
+
+		// MediaWiki uses [[link|text]], while GitHub uses [[text|link]]
+		// It makes page handling terrible, but we prefer GitHub syntax
+		// And fall back to MediaWiki only when it is obvious from the look
+		// Of text and link contents
+		sl := bytes.Split(m, []byte("|"))
+		for _, v := range sl {
+			switch bytes.Count(v, []byte("=")) {
+
+			// Piped args without = sign, these are mandatory arguments
+			case 0:
+				{
+					sv := string(v)
+					if props["name"] == "" {
+						if isLink(v) {
+							// If we clearly see it is a link, we save it so
+
+							// But first we need to ensure, that if both mandatory args provided
+							// look like links, we stick to GitHub syntax
+							if props["link"] != "" {
+								props["name"] = props["link"]
+							}
+
+							props["link"] = strings.TrimSpace(sv)
+						} else {
+							props["name"] = sv
+						}
+					} else {
+						props["link"] = strings.TrimSpace(sv)
+					}
+				}
+
+			// Piped args with = sign, these are optional arguments
+			case 1:
+				{
+					sep := firstIndexOfByte(v, '=')
+					key, val := string(v[:sep]), html.UnescapeString(string(v[sep+1:]))
+					lastCharIndex := len(val) - 1
+					if (val[0] == '"' || val[0] == '\'') && (val[lastCharIndex] == '"' || val[lastCharIndex] == '\'') {
+						val = val[1:lastCharIndex]
+					}
+					props[key] = val
+				}
+			}
+		}
+
+		var name string
+		var link string
+		if props["link"] != "" {
+			link = props["link"]
+		} else if props["name"] != "" {
+			link = props["name"]
+		}
+		if props["title"] != "" {
+			name = props["title"]
+		} else if props["name"] != "" {
+			name = props["name"]
+		} else {
+			name = link
+		}
+
+		name += string(tail)
+		image := false
+		ext := filepath.Ext(string(link))
+		if ext != "" {
+			switch ext {
+			case ".jpg", ".jpeg", ".png", ".tif", ".tiff", ".webp", ".gif", ".bmp", ".ico", ".svg":
+				{
+					image = true
+				}
+			}
+		}
+		absoluteLink := isLink([]byte(link))
+		if !absoluteLink {
+			link = strings.Replace(link, " ", "+", -1)
+		}
+		if image {
+			if !absoluteLink {
+				if IsSameDomain(urlPrefix) {
+					urlPrefix = strings.Replace(urlPrefix, "/src/", "/raw/", 1)
+				}
+				if isWikiMarkdown {
+					link = URLJoin("wiki", "raw", link)
+				}
+				link = URLJoin(urlPrefix, link)
+			}
+			title := props["title"]
+			if title == "" {
+				title = props["alt"]
+			}
+			if title == "" {
+				title = path.Base(string(name))
+			}
+			alt := props["alt"]
+			if alt == "" {
+				alt = name
+			}
+			if alt != "" {
+				alt = `alt="` + alt + `"`
+			}
+			name = fmt.Sprintf(`<img src="%s" %s title="%s" />`, link, alt, title)
+		} else if !absoluteLink {
+			if isWikiMarkdown {
+				link = URLJoin("wiki", link)
+			}
+			link = URLJoin(urlPrefix, link)
+		}
+		if noLink {
+			rawBytes = bytes.Replace(rawBytes, orig, []byte(name), -1)
+		} else {
+			rawBytes = bytes.Replace(rawBytes, orig,
+				[]byte(fmt.Sprintf(`<a href="%s">%s</a>`, link, name)), -1)
+		}
+	}
+	return rawBytes
+}
+
+// RenderCrossReferenceIssueIndexPattern renders issue indexes from other repositories to corresponding links.
+func RenderCrossReferenceIssueIndexPattern(rawBytes []byte, urlPrefix string, metas map[string]string) []byte {
+	ms := CrossReferenceIssueNumericPattern.FindAll(rawBytes, -1)
+	for _, m := range ms {
+		if m[0] == ' ' || m[0] == '(' {
+			m = m[1:] // ignore leading space or opening parentheses
+		}
+
+		repo := string(bytes.Split(m, []byte("#"))[0])
+		issue := string(bytes.Split(m, []byte("#"))[1])
+
+		link := fmt.Sprintf(`<a href="%s">%s</a>`, URLJoin(setting.AppURL, repo, "issues", issue), m)
+		rawBytes = bytes.Replace(rawBytes, m, []byte(link), 1)
+	}
+	return rawBytes
+}
+
+// renderSha1CurrentPattern renders SHA1 strings to corresponding links that assumes in the same repository.
+func renderSha1CurrentPattern(rawBytes []byte, urlPrefix string) []byte {
+	ms := Sha1CurrentPattern.FindAllSubmatch(rawBytes, -1)
+	for _, m := range ms {
+		hash := m[1]
+		// The regex does not lie, it matches the hash pattern.
+		// However, a regex cannot know if a hash actually exists or not.
+		// We could assume that a SHA1 hash should probably contain alphas AND numerics
+		// but that is not always the case.
+		// Although unlikely, deadbeef and 1234567 are valid short forms of SHA1 hash
+		// as used by git and github for linking and thus we have to do similar.
+		rawBytes = bytes.Replace(rawBytes, hash, []byte(fmt.Sprintf(
+			`<a href="%s">%s</a>`, URLJoin(urlPrefix, "commit", string(hash)), base.ShortSha(string(hash)))), -1)
+	}
+	return rawBytes
+}
+
+// RenderSpecialLink renders mentions, indexes and SHA1 strings to corresponding links.
+func RenderSpecialLink(rawBytes []byte, urlPrefix string, metas map[string]string, isWikiMarkdown bool) []byte {
+	ms := MentionPattern.FindAll(rawBytes, -1)
+	for _, m := range ms {
+		m = m[bytes.Index(m, []byte("@")):]
+		rawBytes = bytes.Replace(rawBytes, m,
+			[]byte(fmt.Sprintf(`<a href="%s">%s</a>`, URLJoin(setting.AppURL, string(m[1:])), m)), -1)
+	}
+
+	rawBytes = RenderFullIssuePattern(rawBytes)
+	rawBytes = RenderShortLinks(rawBytes, urlPrefix, false, isWikiMarkdown)
+	rawBytes = RenderIssueIndexPattern(rawBytes, urlPrefix, metas)
+	rawBytes = RenderCrossReferenceIssueIndexPattern(rawBytes, urlPrefix, metas)
+	rawBytes = renderFullSha1Pattern(rawBytes, urlPrefix)
+	rawBytes = renderSha1CurrentPattern(rawBytes, urlPrefix)
+	return rawBytes
+}
+
+var (
+	leftAngleBracket  = []byte("</")
+	rightAngleBracket = []byte(">")
+)
+
+var noEndTags = []string{"img", "input", "br", "hr"}
+
+// PostProcess treats different types of HTML differently,
+// and only renders special links for plain text blocks.
+func PostProcess(rawHTML []byte, urlPrefix string, metas map[string]string, isWikiMarkdown bool) []byte {
+	startTags := make([]string, 0, 5)
+	var buf bytes.Buffer
+	tokenizer := html.NewTokenizer(bytes.NewReader(rawHTML))
+
+OUTER_LOOP:
+	for html.ErrorToken != tokenizer.Next() {
+		token := tokenizer.Token()
+		switch token.Type {
+		case html.TextToken:
+			buf.Write(RenderSpecialLink([]byte(token.String()), urlPrefix, metas, isWikiMarkdown))
+
+		case html.StartTagToken:
+			buf.WriteString(token.String())
+			tagName := token.Data
+			// If this is an excluded tag, we skip processing all output until a close tag is encountered.
+			if strings.EqualFold("a", tagName) || strings.EqualFold("code", tagName) || strings.EqualFold("pre", tagName) {
+				stackNum := 1
+				for html.ErrorToken != tokenizer.Next() {
+					token = tokenizer.Token()
+
+					// Copy the token to the output verbatim
+					buf.Write(RenderShortLinks([]byte(token.String()), urlPrefix, true, isWikiMarkdown))
+
+					if token.Type == html.StartTagToken && !com.IsSliceContainsStr(noEndTags, token.Data) {
+						stackNum++
+					}
+
+					// If this is the close tag to the outer-most, we are done
+					if token.Type == html.EndTagToken {
+						stackNum--
+
+						if stackNum <= 0 && strings.EqualFold(tagName, token.Data) {
+							break
+						}
+					}
+				}
+				continue OUTER_LOOP
+			}
+
+			if !com.IsSliceContainsStr(noEndTags, tagName) {
+				startTags = append(startTags, tagName)
+			}
+
+		case html.EndTagToken:
+			if len(startTags) == 0 {
+				buf.WriteString(token.String())
+				break
+			}
+
+			buf.Write(leftAngleBracket)
+			buf.WriteString(startTags[len(startTags)-1])
+			buf.Write(rightAngleBracket)
+			startTags = startTags[:len(startTags)-1]
+		default:
+			buf.WriteString(token.String())
+		}
+	}
+
+	if io.EOF == tokenizer.Err() {
+		return buf.Bytes()
+	}
+
+	// If we are not at the end of the input, then some other parsing error has occurred,
+	// so return the input verbatim.
+	return rawHTML
+}