[vweb] Error parsing url with // appended

[billpcs]

Describe the bug

If a user tries to load a vweb webpage and the url ends with //, then the page fails to load.

This can have various consequences. For example gitly shows a Cloudflare error currently.

My cloud-deployed server goes to 100% CPU.

Locally, I just get an error on the browser.

Reproduction Steps

Create simple web server project

$ v new --web test

Run the server

$ v run .

Visit the problematic path

Load http://localhost:8082// on a web browser

Expected Behavior

The webpage loads. It either redirects to home, displays a 404 error or something normal.

Current Behavior

The webpage shows The connection was reset on Firefox and This page isn’t working on Chrome

The log shows

[vweb] tid: 005, error parsing path: net.urllib.parse: failed parsing url
[vweb] tid: 000, error parsing path: net.urllib.parse: failed parsing url
[vweb] tid: 006, error parsing path: net.urllib.parse: failed parsing url
[vweb] tid: 001, error parsing path: net.urllib.parse: failed parsing url
[vweb] tid: 002, error parsing path: net.urllib.parse: failed parsing url
[vweb] tid: 004, error parsing path: net.urllib.parse: failed parsing url
[vweb] tid: 003, error parsing path: net.urllib.parse: failed parsing url
[vweb] tid: 005, error parsing path: net.urllib.parse: failed parsing url
[vweb] tid: 003, error parsing path: net.urllib.parse: failed parsing url
[vweb] tid: 000, error parsing path: net.urllib.parse: failed parsing url
[vweb] tid: 002, error parsing path: net.urllib.parse: failed parsing url

Possible Solution

No response

Additional Information/Context

Related to this gitly issue vlang/gitly#253

V version

V 0.4.4 4640627

Environment details (OS name and version, etc.)

V full version: V 0.4.4 aa28efc.4640627
OS: linux, Ubuntu 20.04.6 LTS
Processor: 8 cpus, 64bit, little endian, Intel(R) Core(TM) i7-3630QM CPU @ 2.40GHz

getwd: /home/bill/test
vexe: /home/bill/Documents/opt/v/v
vexe mtime: 2024-01-10 21:20:23

vroot: OK, value: /home/bill/Documents/opt/v
VMODULES: OK, value: /home/bill/.vmodules
VTMP: OK, value: /tmp/v_1000

Git version: git version 2.25.1
Git vroot status: weekly.2021.46-5307-g46406277
.git/config present: true

CC version: cc (Ubuntu 9.4.0-1ubuntu1~20.04.2) 9.4.0
thirdparty/tcc status: thirdparty-linux-amd64 12f392c3

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[billpcs]

Some further information regarding the call hierarchy that leads to this error.

Inside vweb::handle_conn, a function named http.parse_request gets called, which is responsible to fill in the req.url field.

http.parse_request ends up calling http.parse_request_line that internally uses urllib.parse, our culprit.

The parsed value returned in req.url is once more parsed directly inside vweb::handle_conn

What happens is that req.url is filled with the empty string, which when parsed for the second time, returns the

eprintln('[vweb] tid: ${tid:03d}, error parsing path: ${err}')

A probable fix is this, inside urllib.parse_url

...
if rest == '//' {
  // do nothing, protect this special case
}
else if ((url.scheme != '' || !via_request) && !rest.starts_with('///')) && rest.starts_with('//') {
...