Display of FTP links in markdown

[bkmgit]

• Gitea version (or commit ref): 1.9.3
• Git version: 2.1.9
• Operating system: Cent OS 7
• Database (use [x]):
  • PostgreSQL
  • MySQL
  • MariaDB
  • MSSQL
  • SQLite
• Can you reproduce the bug at https://try.gitea.io:
  • [ X] Yes (provide example URL) https://try.gitea.io/bkmgit/TestMarkdown/src/branch/master/README.md
  • No
  • Not relevant
• Log gist:

Description

Markdown does not render ftp links correctly
Similar issue appears here
...

Screenshots

[guillep2k]

I thought it was intentional after reading this:
Google Chrome 82 won't support FTP anymore

[bkmgit]

It seems Markdown is rendered using gomarkdown
A number of sites offer ftp, in particular for download only, and it is helpful to be able to link directly to these. Not all people, use Chrome. Being able to view contents and download from a browser is helpful. A number of places in the world have slow internet connections, where a factor of two difference in download speed is significant, some numbers here. While ftp is not as secure as the other protocols, one can still verify a download using a hash eg. sha256sum.

[bkmgit]

Seems blackfriday supports links to ftp sites, https://github.com/russross/blackfriday/blob/master/inline_test.go

[bkmgit]

• It may be helpful to add the option blackfriday.EXTENSION_AUTOLINK | in https://github.com/go-gitea/gitea/blob/master/modules/markup/markdown/markdown.go at around line 126
• Currently seem to be using blackfriday v1, might it be worth upgrading to blackfriday v2?

[bkmgit]

• URI entries that can be made links are determined by following bluemonday policies. In gitea these are set by line 40 of modules/markup/sanitizer.go which currently uses defaults from bluemonday, which are equivalent to sanitizer.policy.AllowURLSchemes("mailto", "http", "https"). To enable links to ftp, possibly also git and other protocols one observes that line 146 in /custom/conf/app.ini.sample is CUSTOM_URL_SCHEMES =
  and modifying it to
  CUSTOM_URL_SCHEMES = https,http,mailto,ftp,git
  and update the documentation on this configuration option would allow easy setting of what links will be set as hyperlinks rather than rendered as plain text. On an install of Gitea on Cent OS 7, by adding an entry to the /etc/gitea/app.ini with

[markdown]
CUSTOM_URL_SCHEMES = https,http,mailto,ftp
could get hyperlinks with ftp protcol.

• It seems that Macaron is used to serve the webpages. Changing modules/validation/validurl_test.go to allow for all links in app.ini would probably also be helpful.

• Documentation similar to what is available for configuring Black Monday in Hugo, here would likely be helpful for those for whom the defaults are not the best choice. At present documentation configuration cheat sheet is lacking a section on markdown parsing, although the link to sample configuration file app.ini.sample does have this.

[bkmgit]

If updating the documentation on Markdown display is useful, can do this.

[guillep2k]

Hey, don't sweat it. I too wondered "why doesn't this support ftp?" when browsing that part of the code. If nobody is against it, I might take this within next week. However, with our current release schedule I'm not sure when will it be released.

[bkmgit]

@guillep2k Ok. Partially addressed in #8497 and #8498

[bkmgit]

@guillep2k Thanks for implementing #8496