[Bug Report] Relative links in markdown

[schorsch13]

Introduction

When using relative links in markdown files you have to use either ./file.md or file.md. When trying to use /file.md you will get redirected to the root of the gitea instance.

Example

https://try.gitea.io/schorsch/relative-links-in-markdown

Proposal

Change /file.md from directing to the web root to the project root

Credits

The bug was discovered by the codeberg user ivan-paleo. For further information have a look at the issue at codeberg: https://codeberg.org/Codeberg/Community/issues/252

[zeripath]

This was fixed at some point and something has caused a regression!!

[zeripath]

Yes this was fixed in #15088

This is particularly irritating as there was even a test created to prevent this from happening YET AGAIN

[zeripath]

Let's just go through this again.

The base url for an image link rendered in a file GH is:

/owner/repo/blob/branch/path/to/file/

Relative links may traverse out of the repo i.e. if a file that is in / of owner/repo on the default branch master has a link:

../../../../owner2/repo2

then it would like to /owner2/repo2 directly.

Links that start with a / e.g. /../../../owner2/repo2 do not traverse out of the repo. This is not true!

Essentially a leading / is dropped from the links and then the path is made relative to the branch link

---

I'll do some more test cases in pathological and properly add tests to gitea to prevent this from happening yet again.

---

Now in issues and presumably elsewhere the opposite happens:

A

/A

../A

../../A

../../../A
../../../../A
../../../../../A
../../../../../../A

/../A

[zeripath]

OK I guess we need the following (this is for a gitea mounted on a suburl /gitea):

name	input	file	fileInDir	wiki	issue
samedir	file	/gitea/gogits/gogs/src/branch/master/file	/gitea/gogits/gogs/src/branch/master/subdir/file	/gitea/gogits/gogs/wiki/file	/gitea/gogits/gogs/issues/file
childir	subdir/file	/gitea/gogits/gogs/src/branch/master/subdir/file	/gitea/gogits/gogs/src/branch/master/subdir/subdir/file	/gitea/gogits/gogs/wiki/subdir/file	/gitea/gogits/gogs/issues/subdir/file
/file	/file	/gitea/gogits/gogs/src/branch/master/file	/gitea/gogits/gogs/src/branch/master/file	/gitea/file	/gitea/file
../file	../file	/gitea/gogits/gogs/src/branch/file	/gitea/gogits/gogs/src/branch/master/file	/gitea/gogits/gogs/file	/gitea/gogits/gogs/file
/../file	/../file	/gitea/gogits/gogs/src/branch/file	/gitea/gogits/gogs/src/branch/file	/gitea/file	/gitea/file
../../file	../../file	/gitea/gogits/gogs/src/file	/gitea/gogits/gogs/src/branch/file	/gitea/gogits/file	/gitea/gogits/file
/../../file	/../../file	/gitea/gogits/gogs/src/file	/gitea/gogits/gogs/src/file	/gitea/file	/gitea/file
../../../file	../../../file	/gitea/gogits/gogs/file	/gitea/gogits/gogs/src/file	/gitea/file	/gitea/file
../../../../file	../../../../file	/gitea/gogits/file	/gitea/gogits/gogs/file	/gitea/file	/gitea/file
../../../../../file	../../../../../file	/gitea/file	/gitea/gogits/file	/gitea/file	/gitea/file
../../../../../../file	../../../../../../file	/gitea/file	/gitea/file	/gitea/file	/gitea/file
../../../../../../../file	../../../../../../../file	/gitea/file	/gitea/file	/gitea/file	/gitea/file

One slight problem is that this this is still not github compatible - githubs blob urls are:

https://github.com/zeripath/pathological/blob/master/README.md

Whereas the equivalent in Gitea:

https://try.gitea.io/arandomer/pathological/src/branch/master/README.md

So we're already slightly incompatible.

However, the / behaviour would be the least we should do.

[zeripath]

TestCase to add to modules/markup/markdown/markdown_test.go

func TestRender_RelativeLinks(t *testing.T) {
	setting.AppURL = "https://localhost:3000/gitea/"
	setting.AppSubURL = "/gitea"

	testcases := []struct {
		name              string
		input             string
		expectedFile      string
		expectedFileInDir string
		expectedWiki      string
		expectedIssue     string
	}{
		{
			name:              "samedir",
			input:             "file",
			expectedFile:      "/gitea/gogits/gogs/src/branch/master/file",
			expectedFileInDir: "/gitea/gogits/gogs/src/branch/master/subdir/file",
			expectedWiki:      "/gitea/gogits/gogs/wiki/file",
			expectedIssue:     "/gitea/gogits/gogs/issues/file",
		},
		{
			name:              "childir",
			input:             "subdir/file",
			expectedFile:      "/gitea/gogits/gogs/src/branch/master/subdir/file",
			expectedFileInDir: "/gitea/gogits/gogs/src/branch/master/subdir/subdir/file",
			expectedWiki:      "/gitea/gogits/gogs/wiki/subdir/file",
			expectedIssue:     "/gitea/gogits/gogs/issues/subdir/file",
		},
		{
			name:              "/file",
			input:             "/file",
			expectedFile:      "/gitea/gogits/gogs/src/branch/master/file",
			expectedFileInDir: "/gitea/gogits/gogs/src/branch/master/file",
			expectedWiki:      "/gitea/file",
			expectedIssue:     "/gitea/file",
		},
		{
			name:              "../file",
			input:             "../file",
			expectedFile:      "/gitea/gogits/gogs/src/branch/file",
			expectedFileInDir: "/gitea/gogits/gogs/src/branch/master/file",
			expectedWiki:      "/gitea/gogits/gogs/file",
			expectedIssue:     "/gitea/gogits/gogs/file",
		},
		{
			name:              "/../file",
			input:             "/../file",
			expectedFile:      "/gitea/gogits/gogs/src/branch/file",
			expectedFileInDir: "/gitea/gogits/gogs/src/branch/file",
			expectedWiki:      "/gitea/file",
			expectedIssue:     "/gitea/file",
		},
		{
			name:              "../../file",
			input:             "../../file",
			expectedFile:      "/gitea/gogits/gogs/src/file",
			expectedFileInDir: "/gitea/gogits/gogs/src/branch/file",
			expectedWiki:      "/gitea/gogits/file",
			expectedIssue:     "/gitea/gogits/file",
		},
		{
			name:              "/../../file",
			input:             "/../../file",
			expectedFile:      "/gitea/gogits/gogs/src/file",
			expectedFileInDir: "/gitea/gogits/gogs/src/file",
			expectedWiki:      "/gitea/file",
			expectedIssue:     "/gitea/file",
		},
		{
			name:              "../../../file",
			input:             "../../../file",
			expectedFile:      "/gitea/gogits/gogs/file",
			expectedFileInDir: "/gitea/gogits/gogs/src/file",
			expectedWiki:      "/gitea/file",
			expectedIssue:     "/gitea/file",
		},
		{
			name:              "../../../../file",
			input:             "../../../../file",
			expectedFile:      "/gitea/gogits/file",
			expectedFileInDir: "/gitea/gogits/gogs/file",
			expectedWiki:      "/gitea/file",
			expectedIssue:     "/gitea/file",
		},
		{
			name:              "../../../../../file",
			input:             "../../../../../file",
			expectedFile:      "/gitea/file",
			expectedFileInDir: "/gitea/gogits/file",
			expectedWiki:      "/gitea/file",
			expectedIssue:     "/gitea/file",
		},
		{
			name:              "../../../../../../file",
			input:             "../../../../../../file",
			expectedFile:      "/gitea/file",
			expectedFileInDir: "/gitea/file",
			expectedWiki:      "/gitea/file",
			expectedIssue:     "/gitea/file",
		},
		{
			name:              "../../../../../../../file",
			input:             "../../../../../../../file",
			expectedFile:      "/gitea/file",
			expectedFileInDir: "/gitea/file",
			expectedWiki:      "/gitea/file",
			expectedIssue:     "/gitea/file",
		},
	}

	for _, testcase := range testcases {
		t.Run(testcase.name, func(t *testing.T) {
			t.Run("file", func(t *testing.T) {
				buffer, err := RenderString(&markup.RenderContext{
					URLPrefix: setting.AppSubURL + "/" + Repo + "/src/branch/master/",
					Filename:  "test.md",
					Metas: map[string]string{
						"user":     "gogits",
						"repo":     "gogs",
						"repoPath": "../../../integrations/gitea-repositories-meta/user13/repo11.git/",
					},
				}, "["+testcase.input+"]("+testcase.input+")")
				assert.NoError(t, err)
				assert.Equal(t, fmt.Sprintf("<p><a href=\"%s\" rel=\"nofollow\">%s</a></p>", testcase.expectedFile, testcase.input), strings.TrimSpace(buffer), "Incorrect file path")
			})
			t.Run("fileInDir", func(t *testing.T) {
				buffer, err := RenderString(&markup.RenderContext{
					URLPrefix: setting.AppSubURL + "/" + Repo + "/src/branch/master/subdir/",
					Filename:  "test.md",
					Metas: map[string]string{
						"user":     "gogits",
						"repo":     "gogs",
						"repoPath": "../../../integrations/gitea-repositories-meta/user13/repo11.git/",
					},
				}, "["+testcase.input+"]("+testcase.input+")")
				assert.NoError(t, err)
				assert.Equal(t, fmt.Sprintf("<p><a href=\"%s\" rel=\"nofollow\">%s</a></p>", testcase.expectedFileInDir, testcase.input), strings.TrimSpace(buffer), "Incorrect subdir file path")
			})
			t.Run("wiki", func(t *testing.T) {
				buffer, err := RenderString(&markup.RenderContext{
					URLPrefix: setting.AppSubURL + "/" + Repo,
					IsWiki:    true,
					Metas: map[string]string{
						"user":     "gogits",
						"repo":     "gogs",
						"repoPath": "../../../integrations/gitea-repositories-meta/user13/repo11.git/",
					},
				}, "["+testcase.input+"]("+testcase.input+")")
				assert.NoError(t, err)
				assert.Equal(t, fmt.Sprintf("<p><a href=\"%s\" rel=\"nofollow\">%s</a></p>", testcase.expectedWiki, testcase.input), strings.TrimSpace(buffer), "Incorrect wiki path")
			})
			t.Run("comment", func(t *testing.T) {
				buffer, err := RenderString(&markup.RenderContext{
					URLPrefix: setting.AppSubURL + "/" + Repo + "/issues/",
					Metas: map[string]string{
						"user":     "gogits",
						"repo":     "gogs",
						"repoPath": "../../../integrations/gitea-repositories-meta/user13/repo11.git/",
						"mode":     "comment",
					},
				}, "["+testcase.input+"]("+testcase.input+")")
				assert.NoError(t, err)
				assert.Equal(t, fmt.Sprintf("<p><a href=\"%s\" rel=\"nofollow\">%s</a></p>", testcase.expectedIssue, testcase.input), strings.TrimSpace(buffer), "Incorrect issue path")
			})
		})
	}
}

[charles-997]

Has there been any progress on this bug? This seems like a reasonably important feature-breaking bug!
I was surprised to see that my relative links in existing repositories do not function properly in Gitea.

[xbreaker]

Same problem with using HTML A tag in markdown with relative file name

Steps:

1. Create markdown file with HTML tag A and link to local file (for example, <a href="readme.md>readme</a>)
2. Save file, link will lost current path, if you viewing branch link will be /repo/src/branch/file.md instead of /repo/src/branch/main/file.md

Demo: https://try.gitea.io/aybe/markdown-branch/

[lunny]

From https://try.gitea.io/aybe/markdown-branch/ , only relative link from a tag is wrong. Maybe it's accepted?

[ell1e]

I just ran into this, sadly it seems to break almost all links in my documentation so this is a really high impact bug in my opinion. Especially since with the GitHub mirror it works fine.

Here's a demo file with a link that should work but it doesn't:

https://try.gitea.io/blablablablab/BlaTest/src/branch/main/A%20B/outsidelink.md

(The big bold (test link) is what you want to click. Expected behavior is that it gets you to the target file in the repository root, actual behavior is some nonsensical location.)

[vilunov]

In original post it is said that relative links such as [text](file.md) or [text](./file.md) resolve correctly, but absolute ones do not. This is not my experience with Gitea 1.21.4. Example (this was fixed by downgrading to 1.21.3)

I expect that a link such as [Project structure](crates/readme.md) in the project readme should be resolved to example.com/org/repo/src/branch/main/crates/readme.md, instead it is resolved to example.com/org/repo/crates/readme.md, making it pretty much useless, as it is always broken.

[vilunov]

The issue above seems to be a regression between 1.21.3 and 1.21.4, probably even by #28803
Fortunately, there was no migration in 1.21.4, it was easy to downgrade one patch version

[LamaBleu]

Thank you so much @vilunov, you saved my day. Downgrade to 1.21.3 solved this annoying issue.

[vilunov]

@KN4CK3R sorry, pinging for visibility since you made the MR and you seem to be responsible for that area.