Multiple Escaping Improvements (#17551)

There are multiple places where Gitea does not properly escape URLs that it is building and there are multiple places where it builds urls when there is already a simpler function available to use this.
    
This is an extensive PR attempting to fix these issues.

1. The first commit in this PR looks through all href, src and links in the Gitea codebase and has attempted to catch all the places where there is potentially incomplete escaping.
2. Whilst doing this we will prefer to use functions that create URLs over recreating them by hand.
3. All uses of strings should be directly escaped - even if they are not currently expected to contain escaping characters. The main benefit to doing this will be that we can consider relaxing the constraints on user names and reponames in future. 
4. The next commit looks at escaping in the wiki and re-considers the urls that are used there. Using the improved escaping here wiki files containing '/'. (This implementation will currently still place all of the wiki files the root directory of the repo but this would not be difficult to change.)
5. The title generation in feeds is now properly escaped.
6. EscapePound is no longer needed - urls should be PathEscaped / QueryEscaped as necessary but then re-escaped with Escape when creating html with locales Signed-off-by: Andrew Thornton <art27@cantab.net>

Signed-off-by: Andrew Thornton <art27@cantab.net>

2 files changed, 33 insertions, 21 deletions

diff --git a/modules/context/context.go b/modules/context/context.go
index cb7131907e..8adf1f306b 100644
--- a/modules/context/context.go
+++ b/modules/context/context.go
@@ -70,6 +70,16 @@ type Context struct {
 	Org  *Organization
 }
 
+// TrHTMLEscapeArgs runs Tr but pre-escapes all arguments with html.EscapeString.
+// This is useful if the locale message is intended to only produce HTML content.
+func (ctx *Context) TrHTMLEscapeArgs(msg string, args ...string) string {
+	trArgs := make([]interface{}, len(args))
+	for i, arg := range args {
+		trArgs[i] = html.EscapeString(arg)
+	}
+	return ctx.Tr(msg, trArgs...)
+}
+
 // GetData returns the data
 func (ctx *Context) GetData() map[string]interface{} {
 	return ctx.Data
@@ -120,9 +130,9 @@ func RedirectToUser(ctx *Context, userName string, redirectUserID int64) {
 	}
 
 	redirectPath := strings.Replace(
-		ctx.Req.URL.Path,
-		userName,
-		user.Name,
+		ctx.Req.URL.EscapedPath(),
+		url.PathEscape(userName),
+		url.PathEscape(user.Name),
 		1,
 	)
 	if ctx.Req.URL.RawQuery != "" {
diff --git a/modules/context/repo.go b/modules/context/repo.go
index d5763c78a3..3be33f2483 100644
--- a/modules/context/repo.go
+++ b/modules/context/repo.go
@@ -41,10 +41,10 @@ var IssueTemplateDirCandidates = []string{
 
 // PullRequest contains information to make a pull request
 type PullRequest struct {
-	BaseRepo *models.Repository
-	Allowed  bool
-	SameRepo bool
-	HeadInfo string // [<user>:]<branch>
+	BaseRepo       *models.Repository
+	Allowed        bool
+	SameRepo       bool
+	HeadInfoSubURL string // [<user>:]<branch> url segment
 }
 
 // Repository contains information to operate a repository
@@ -189,11 +189,11 @@ func (r *Repository) GetCommitGraphsCount(hidePRRefs bool, branches []string, fi
 func (r *Repository) BranchNameSubURL() string {
 	switch {
 	case r.IsViewBranch:
-		return "branch/" + r.BranchName
+		return "branch/" + util.PathEscapeSegments(r.BranchName)
 	case r.IsViewTag:
-		return "tag/" + r.BranchName
+		return "tag/" + util.PathEscapeSegments(r.BranchName)
 	case r.IsViewCommit:
-		return "commit/" + r.BranchName
+		return "commit/" + util.PathEscapeSegments(r.BranchName)
 	}
 	log.Error("Unknown view type for repo: %v", r)
 	return ""
@@ -321,9 +321,9 @@ func RedirectToRepo(ctx *Context, redirectRepoID int64) {
 	}
 
 	redirectPath := strings.Replace(
-		ctx.Req.URL.Path,
-		fmt.Sprintf("%s/%s", ownerName, previousRepoName),
-		repo.FullName(),
+		ctx.Req.URL.EscapedPath(),
+		url.PathEscape(ownerName)+"/"+url.PathEscape(previousRepoName),
+		url.PathEscape(repo.OwnerName)+"/"+url.PathEscape(repo.Name),
 		1,
 	)
 	if ctx.Req.URL.RawQuery != "" {
@@ -588,7 +588,7 @@ func RepoAssignment(ctx *Context) (cancel context.CancelFunc) {
 		ctx.Data["BaseRepo"] = repo.BaseRepo
 		ctx.Repo.PullRequest.BaseRepo = repo.BaseRepo
 		ctx.Repo.PullRequest.Allowed = canPush
-		ctx.Repo.PullRequest.HeadInfo = ctx.Repo.Owner.Name + ":" + ctx.Repo.BranchName
+		ctx.Repo.PullRequest.HeadInfoSubURL = url.PathEscape(ctx.Repo.Owner.Name) + ":" + util.PathEscapeSegments(ctx.Repo.BranchName)
 	} else if repo.AllowsPulls() {
 		// Or, this is repository accepts pull requests between branches.
 		canCompare = true
@@ -596,7 +596,7 @@ func RepoAssignment(ctx *Context) (cancel context.CancelFunc) {
 		ctx.Repo.PullRequest.BaseRepo = repo
 		ctx.Repo.PullRequest.Allowed = canPush
 		ctx.Repo.PullRequest.SameRepo = true
-		ctx.Repo.PullRequest.HeadInfo = ctx.Repo.BranchName
+		ctx.Repo.PullRequest.HeadInfoSubURL = util.PathEscapeSegments(ctx.Repo.BranchName)
 	}
 	ctx.Data["CanCompareOrPull"] = canCompare
 	ctx.Data["PullRequestCtx"] = ctx.Repo.PullRequest
@@ -621,7 +621,7 @@ func RepoAssignment(ctx *Context) (cancel context.CancelFunc) {
 
 	if ctx.FormString("go-get") == "1" {
 		ctx.Data["GoGetImport"] = ComposeGoGetImport(owner.Name, repo.Name)
-		prefix := setting.AppURL + path.Join(owner.Name, repo.Name, "src", "branch", ctx.Repo.BranchName)
+		prefix := repo.HTMLURL() + "/src/branch/" + util.PathEscapeSegments(ctx.Repo.BranchName)
 		ctx.Data["GoDocDirectory"] = prefix + "{/dir}"
 		ctx.Data["GoDocFile"] = prefix + "{/dir}/{file}#L{line}"
 	}
@@ -810,7 +810,7 @@ func RepoRefByType(refType RepoRefType, ignoreNotExistErr ...bool) func(*Context
 			if isRenamedBranch && has {
 				renamedBranchName := ctx.Data["RenamedBranchName"].(string)
 				ctx.Flash.Info(ctx.Tr("repo.branch.renamed", refName, renamedBranchName))
-				link := strings.Replace(ctx.Req.RequestURI, refName, renamedBranchName, 1)
+				link := setting.AppSubURL + strings.Replace(ctx.Req.URL.EscapedPath(), util.PathEscapeSegments(refName), util.PathEscapeSegments(renamedBranchName), 1)
 				ctx.Redirect(link)
 				return
 			}
@@ -845,7 +845,7 @@ func RepoRefByType(refType RepoRefType, ignoreNotExistErr ...bool) func(*Context
 				// If short commit ID add canonical link header
 				if len(refName) < 40 {
 					ctx.Header().Set("Link", fmt.Sprintf("<%s>; rel=\"canonical\"",
-						util.URLJoin(setting.AppURL, strings.Replace(ctx.Req.URL.RequestURI(), refName, ctx.Repo.Commit.ID.String(), 1))))
+						util.URLJoin(setting.AppURL, strings.Replace(ctx.Req.URL.RequestURI(), util.PathEscapeSegments(refName), url.PathEscape(ctx.Repo.Commit.ID.String()), 1))))
 				}
 			} else {
 				if len(ignoreNotExistErr) > 0 && ignoreNotExistErr[0] {
@@ -857,11 +857,13 @@ func RepoRefByType(refType RepoRefType, ignoreNotExistErr ...bool) func(*Context
 
 			if refType == RepoRefLegacy {
 				// redirect from old URL scheme to new URL scheme
+				prefix := strings.TrimPrefix(setting.AppSubURL+strings.TrimSuffix(ctx.Req.URL.Path, ctx.Params("*")), ctx.Repo.RepoLink)
+
 				ctx.Redirect(path.Join(
-					setting.AppSubURL,
-					strings.TrimSuffix(ctx.Req.URL.Path, ctx.Params("*")),
+					ctx.Repo.RepoLink,
+					util.PathEscapeSegments(prefix),
 					ctx.Repo.BranchNameSubURL(),
-					ctx.Repo.TreePath))
+					util.PathEscapeSegments(ctx.Repo.TreePath)))
 				return
 			}
 		}