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// Copyright 2016 `multipart` Crate Developers
// Licensed under the Apache License, Version 2.0, <LICENSE-APACHE or
//> or the MIT license <LICENSE-MIT or
//>, at your option. This file may not be
// copied, modified, or distributed except according to those terms.
//! Sized/buffered wrapper around `HttpRequest`.
use client::{HttpRequest, HttpStream};
use std::io;
use std::io::prelude::*;
/// A wrapper around a request object that measures the request body and sets the `Content-Length`
/// header to its size in bytes.
/// Sized requests are more human-readable and use less bandwidth
/// (as chunking adds [visual noise and overhead][chunked-example]),
/// but they must be able to load their entirety, including the contents of all files
/// and streams, into memory so the request body can be measured.
/// You should really only use sized requests if you intend to inspect the data manually on the
/// server side, as it will produce a more human-readable request body. Also, of course, if the
/// server doesn't support chunked requests or otherwise rejects them.
/// [chunked-example]:
pub struct SizedRequest<R> {
inner: R,
buffer: Vec<u8>,
boundary: String,
impl<R: HttpRequest> SizedRequest<R> {
pub fn from_request(req: R) -> SizedRequest<R> {
SizedRequest {
inner: req,
buffer: Vec::new(),
boundary: String::new(),
impl<R> Write for SizedRequest<R> {
fn write(&mut self, data: &[u8]) -> io::Result<usize> {
fn flush(&mut self) -> io::Result<()> { Ok(()) }
impl<R: HttpRequest> HttpRequest for SizedRequest<R>
where <R::Stream as HttpStream>::Error: From<R::Error> {
type Stream = Self;
type Error = R::Error;
/// `SizedRequest` ignores `_content_len` because it sets its own later.
fn apply_headers(&mut self, boundary: &str, _content_len: Option<u64>) -> bool {
fn open_stream(mut self) -> Result<Self, Self::Error> {
impl<R: HttpRequest> HttpStream for SizedRequest<R>
where <R::Stream as HttpStream>::Error: From<R::Error> {
type Request = Self;
type Response = <<R as HttpRequest>::Stream as HttpStream>::Response;
type Error = <<R as HttpRequest>::Stream as HttpStream>::Error;
fn finish(mut self) -> Result<Self::Response, Self::Error> {
let content_len = self.buffer.len() as u64;
if !self.inner.apply_headers(&self.boundary, Some(content_len)) {
return Err(io::Error::new(
"SizedRequest failed to apply headers to wrapped request."
let mut req = self.inner.open_stream()?;
io::copy(&mut &self.buffer[..], &mut req)?;