Skip to content

wasi-http: don't send forbidden headers #136

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Closed
pchickey wants to merge 3 commits into from
Closed

wasi-http: don't send forbidden headers #136

Show file tree
Hide file tree
Changes from 2 commits
Commits
Show all changes
3 commits
Select commit Hold shift + click to select a range
c2fab21
header map translation: do not set FORBIDDEN_HEADERS
pchickey Jul 17, 2026
0b0692c
server: do not add a Content-Length header
pchickey Jul 17, 2026
35872be
lowercase search
pchickey Jul 20, 2026
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
23 changes: 19 additions & 4 deletions src/http/fields.rs
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -18,10 +18,25 @@ pub(crate) fn header_map_from_wasi(wasi_fields: Fields) -> Result<HeaderMap, Err
pub(crate) fn header_map_to_wasi(header_map: &HeaderMap) -> Result<Fields, Error> {
let wasi_fields = Fields::new();
for (key, value) in header_map {
// Unwrap because `HeaderMap` has already validated the headers.
wasi_fields
.append(key.as_str(), value.as_bytes())
.with_context(|| format!("wasi rejected header `{key}: {value:?}`"))?
if !FORBIDDEN_HEADERS.contains(key) {

@avahahn avahahn Jul 20, 2026

Copy link
Copy Markdown

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

while technically HTTP headers are case sensitive, ones like Content-Length are not usually handled that way.

I recommend normalizing every entry in FORBIDDEN_HEADERS to be lowercase and also to use key.to_ascii_lowercase() here in this contains call as well.

wasi_fields
.append(key.as_str(), value.as_bytes())
.with_context(|| format!("wasi rejected header `{key}: {value:?}`"))?
}
}
Ok(wasi_fields)
}

const FORBIDDEN_HEADERS: [HeaderName; 11] = [
http::header::CONNECTION,
HeaderName::from_static("keep-alive"),
http::header::PROXY_AUTHENTICATE,
http::header::PROXY_AUTHORIZATION,
HeaderName::from_static("proxy-connection"),
http::header::TRANSFER_ENCODING,
http::header::UPGRADE,
http::header::HOST,
HeaderName::from_static("http2-settings"),
http::header::EXPECT,
http::header::CONTENT_LENGTH,
];
9 changes: 0 additions & 9 deletions src/http/server.rs
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -19,7 +19,6 @@
//! [`http_server`]: crate::http_server

use super::{Body, Error, Response, error::ErrorCode, fields::header_map_to_wasi};
use http::header::CONTENT_LENGTH;
use wasip2::exports::http::incoming_handler::ResponseOutparam;
use wasip2::http::types::OutgoingResponse;

Expand All @@ -44,14 +43,6 @@ impl Responder {
// Consume the `response` and prepare to write the body.
let body = response.into_body().into();

// Automatically add a Content-Length header.
if let Some(len) = body.content_length() {
let mut buffer = itoa::Buffer::new();
wasi_headers
.append(CONTENT_LENGTH.as_str(), buffer.format(len).as_bytes())
.unwrap();
}

Comment on lines -47 to -54

@yoshuawuyts yoshuawuyts Jul 19, 2026

Copy link
Copy Markdown
Member

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

I'm surprised this works? I'm looking at Jco's http.ts here, and this might cause problems for it? I'd feel a lot better if we had a test for this in wasi-testsuite to greenlight the behavior before we land it here.

let wasi_response = OutgoingResponse::new(wasi_headers);

// Unwrap because `StatusCode` has already validated the status.
Expand Down
Loading