1 files changed, 165 insertions, 0 deletions
diff --git a/rust/src/http.rs b/rust/src/http.rs
new file mode 100644
index 0000000000..74098f4c8b
--- /dev/null
+++ b/rust/src/http.rs
@@ -0,0 +1,165 @@
+/*
+ * This file is licensed under the Affero General Public License (AGPL) version 3.
+ *
+ * Copyright (C) 2024 New Vector, Ltd
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as
+ * published by the Free Software Foundation, either version 3 of the
+ * License, or (at your option) any later version.
+ *
+ * See the GNU Affero General Public License for more details:
+ * <https://www.gnu.org/licenses/agpl-3.0.html>.
+ */
+
+use bytes::{Buf, BufMut, Bytes, BytesMut};
+use headers::{Header, HeaderMapExt};
+use http::{HeaderName, HeaderValue, Method, Request, Response, StatusCode, Uri};
+use pyo3::{
+    exceptions::PyValueError,
+    types::{PyBytes, PySequence, PyTuple},
+    PyAny, PyResult,
+};
+
+use crate::errors::SynapseError;
+
+/// Read a file-like Python object by chunks
+///
+/// # Errors
+///
+/// Returns an error if calling the `read` on the Python object failed
+fn read_io_body(body: &PyAny, chunk_size: usize) -> PyResult<Bytes> {
+    let mut buf = BytesMut::new();
+    loop {
+        let bytes: &PyBytes = body.call_method1("read", (chunk_size,))?.downcast()?;
+        if bytes.as_bytes().is_empty() {
+            return Ok(buf.into());
+        }
+        buf.put(bytes.as_bytes());
+    }
+}
+
+/// Transform a Twisted `IRequest` to an [`http::Request`]
+///
+/// It uses the following members of `IRequest`:
+///   - `content`, which is expected to be a file-like object with a `read` method
+///   - `uri`, which is expected to be a valid URI as `bytes`
+///   - `method`, which is expected to be a valid HTTP method as `bytes`
+///   - `requestHeaders`, which is expected to have a `getAllRawHeaders` method
+///
+/// # Errors
+///
+/// Returns an error if the Python object doesn't properly implement `IRequest`
+pub fn http_request_from_twisted(request: &PyAny) -> PyResult<Request<Bytes>> {
+    let content = request.getattr("content")?;
+    let body = read_io_body(content, 4096)?;
+
+    let mut req = Request::new(body);
+
+    let uri: &PyBytes = request.getattr("uri")?.downcast()?;
+    *req.uri_mut() =
+        Uri::try_from(uri.as_bytes()).map_err(|_| PyValueError::new_err("invalid uri"))?;
+
+    let method: &PyBytes = request.getattr("method")?.downcast()?;
+    *req.method_mut() = Method::from_bytes(method.as_bytes())
+        .map_err(|_| PyValueError::new_err("invalid method"))?;
+
+    let headers_iter = request
+        .getattr("requestHeaders")?
+        .call_method0("getAllRawHeaders")?
+        .iter()?;
+
+    for header in headers_iter {
+        let header = header?;
+        let header: &PyTuple = header.downcast()?;
+        let name: &PyBytes = header.get_item(0)?.downcast()?;
+        let name = HeaderName::from_bytes(name.as_bytes())
+            .map_err(|_| PyValueError::new_err("invalid header name"))?;
+
+        let values: &PySequence = header.get_item(1)?.downcast()?;
+        for index in 0..values.len()? {
+            let value: &PyBytes = values.get_item(index)?.downcast()?;
+            let value = HeaderValue::from_bytes(value.as_bytes())
+                .map_err(|_| PyValueError::new_err("invalid header value"))?;
+            req.headers_mut().append(name.clone(), value);
+        }
+    }
+
+    Ok(req)
+}
+
+/// Send an [`http::Response`] through a Twisted `IRequest`
+///
+/// It uses the following members of `IRequest`:
+///
+///  - `responseHeaders`, which is expected to have a `addRawHeader(bytes, bytes)` method
+///  - `setResponseCode(int)` method
+///  - `write(bytes)` method
+///  - `finish()` method
+///
+///  # Errors
+///
+/// Returns an error if the Python object doesn't properly implement `IRequest`
+pub fn http_response_to_twisted<B>(request: &PyAny, response: Response<B>) -> PyResult<()>
+where
+    B: Buf,
+{
+    let (parts, mut body) = response.into_parts();
+
+    request.call_method1("setResponseCode", (parts.status.as_u16(),))?;
+
+    let response_headers = request.getattr("responseHeaders")?;
+    for (name, value) in parts.headers.iter() {
+        response_headers.call_method1("addRawHeader", (name.as_str(), value.as_bytes()))?;
+    }
+
+    while body.remaining() != 0 {
+        let chunk = body.chunk();
+        request.call_method1("write", (chunk,))?;
+        body.advance(chunk.len());
+    }
+
+    request.call_method0("finish")?;
+
+    Ok(())
+}
+
+/// An extension trait for [`HeaderMap`] that provides typed access to headers, and throws the
+/// right python exceptions when the header is missing or fails to parse.
+///
+/// [`HeaderMap`]: headers::HeaderMap
+pub trait HeaderMapPyExt: HeaderMapExt {
+    /// Get a header from the map, returning an error if it is missing or invalid.
+    fn typed_get_required<H>(&self) -> PyResult<H>
+    where
+        H: Header,
+    {
+        self.typed_get_optional::<H>()?.ok_or_else(|| {
+            SynapseError::new(
+                StatusCode::BAD_REQUEST,
+                format!("Missing required header: {}", H::name()),
+                "M_MISSING_PARAM",
+                None,
+                None,
+            )
+        })
+    }
+
+    /// Get a header from the map, returning `None` if it is missing and an error if it is invalid.
+    fn typed_get_optional<H>(&self) -> PyResult<Option<H>>
+    where
+        H: Header,
+    {
+        self.typed_try_get::<H>().map_err(|_| {
+            SynapseError::new(
+                StatusCode::BAD_REQUEST,
+                format!("Invalid header: {}", H::name()),
+                "M_INVALID_PARAM",
+                None,
+                None,
+            )
+        })
+    }
+}
+
+impl<T: HeaderMapExt> HeaderMapPyExt for T {}