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fix: wasix http client: properly forward response headers
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Resolves the TODO, and really needed to be done...
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@theduke
theduke committed Jan 16, 2023
1 parent 5e7517f commit ed15165
Showing 1 changed file with 7 additions and 3 deletions.
10 changes: 7 additions & 3 deletions lib/wasi/src/http/reqwest.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -34,18 +34,22 @@ impl ReqwestHttpClient {

let status = response.status().as_u16();
let status_text = response.status().as_str().to_string();
// TODO: prevent redundant header copy.

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@Michael-F-Bryan

Michael-F-Bryan Jan 17, 2023

Contributor

FYI - I don't think this is possible in general because http::HeaderMap stores headers as a HashMap<HeaderName, Vec<HeaderValue>>, but the consuming into_iter() will yield (Option<HeaderName>, HeaderValue>, where you only get Some for the first occurrence of a particular header.

If we are allowed to silently drop/overwrite duplicate headers, then we can implement it without copies.

let mut headers = Vec::new();

let (parts, body) = response.into_parts();

for (name, value) in parts.headers {
  if let Some(name) = name {
    headers.push(name, value);
  }
}

... Although the HttpResponse type's headers field is a Vec<(String, String)> rather than a Vec<(HeaderName, HeaderValue)>, so you'd need to call .to_string() on things anyway, and we're back where we started.

TL;DR: The string copies are annoying, but we'll probably need to keep them if we want to respect HTTP semantics so you can remove the TODO.

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@theduke

theduke Jan 17, 2023

Author Contributor

The iterator design has annoyed me for years, because it forces you to keep a stateful mutable variable with the most recent header name.

The bindings already look like this:

record header {
  key: string,
  value: list<u8>,
}

type header-list = list<header>

So it's already possible to avoid the copies, I was just in a rush and didn't implement it.
let headers = response
.headers()
.iter()
.map(|(k, v)| (k.to_string(), v.to_str().unwrap().to_string()))
.collect();
let data = response.bytes().await?.to_vec();

// TODO: forward the response headers.

Ok(HttpResponse {
pos: 0usize,
ok: true,
status,
status_text,
redirected: false,
body: Some(data),
headers: Vec::new(),
headers,
})
}
}
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