extern crate arglib_netencode;
extern crate ascii;
extern crate exec_helpers;
extern crate httparse;
extern crate netencode;
use exec_helpers::{die_expected_error, die_temporary, die_user_error};
use std::collections::HashMap;
use std::io::{Read, Write};
use std::os::unix::io::FromRawFd;
use netencode::dec::Decoder;
use netencode::{dec, T, U};
enum What {
Request,
Response,
}
// reads a http request (stdin), and writes all headers to stdout, as netencoded record.
// The keys are text, but can be lists of text iff headers appear multiple times, so beware.
fn main() -> std::io::Result<()> {
exec_helpers::no_args("read-http");
let args = dec::RecordDot {
field: "what",
inner: dec::OneOf {
list: vec!["request", "response"],
inner: dec::Text,
},
};
let what: What = match args.dec(arglib_netencode::arglib_netencode("read-http", None).to_u()) {
Ok("request") => What::Request,
Ok("response") => What::Response,
Ok(v) => panic!("shouldn’t happen!, value was: {}", v),
Err(dec::DecodeError(err)) => die_user_error("read-http", err),
};
fn read_stdin_to_complete<F>(mut parse: F) -> ()
where
F: FnMut(&[u8]) -> httparse::Result<usize>,
{
let mut res = httparse::Status::Partial;
loop {
if let httparse::Status::Complete(_) = res {
return;
}
let mut buf = [0; 2048];
match std::io::stdin().read(&mut buf[..]) {
Ok(size) => {
if size == 0 {
break;
}
}
Err(err) => {
die_temporary("read-http", format!("could not read from stdin, {:?}", err))
}
}
match parse(&buf) {
Ok(status) => {
res = status;
}
Err(err) => {
die_temporary("read-http", format!("httparse parsing failed: {:#?}", err))
}
}
}
}
fn normalize_headers<'a>(headers: &'a [httparse::Header]) -> HashMap<String, U<'a>> {
let mut res = HashMap::new();
for httparse::Header { name, value } in headers {
let val = ascii::AsciiStr::from_ascii(*value)
.expect(&format!(
"read-http: we require header values to be ASCII, but the header {} was {:?}",
name, value
))
.as_str();
// lowercase the header names, since the standard doesn’t care
// and we want unique strings to match against
let name_lower = name.to_lowercase();
match res.insert(name_lower, U::Text(val)) {
None => (),
Some(U::Text(t)) => {
let name_lower = name.to_lowercase();
let _ = res.insert(name_lower, U::List(vec![U::Text(t), U::Text(val)]));
()
}
Some(U::List(mut l)) => {
let name_lower = name.to_lowercase();
l.push(U::Text(val));
let _ = res.insert(name_lower, U::List(l));
()
}
Some(o) => panic!("read-http: header not text nor list: {:?}", o),
}
}
res
}
// tries to read until the end of the http header (deliniated by two newlines "\r\n\r\n")
fn read_till_end_of_header<R: Read>(buf: &mut Vec<u8>, reader: R) -> Option<()> {
let mut chonker = Chunkyboi::new(reader, 4096);
loop {
// TODO: attacker can send looooong input, set upper maximum
match chonker.next() {
Some(Ok(chunk)) => {
buf.extend_from_slice(&chunk);
if chunk.windows(4).any(|c| c == b"\r\n\r\n") {
return Some(());
}
}
Some(Err(err)) => {
die_temporary("read-http", format!("error reading from stdin: {:?}", err))
}
None => return None,
}
}
}
// max header size chosen arbitrarily
let mut headers = [httparse::EMPTY_HEADER; 128];
let stdin = std::io::stdin();
match what {
Request => {
let mut req = httparse::Request::new(&mut headers);
let mut buf: Vec<u8> = vec![];
match read_till_end_of_header(&mut buf, stdin.lock()) {
Some(()) => match req.parse(&buf) {
Ok(httparse::Status::Complete(_body_start)) => {}
Ok(httparse::Status::Partial) => {
die_expected_error("read-http", "httparse should have gotten a full header")
}
Err(err) => die_expected_error(
"read-http",
format!("httparse response parsing failed: {:#?}", err),
),
},
None => die_expected_error(
"read-http",
format!("httparse end of stdin reached before able to parse request headers"),
),
}
let method = req.method.expect("method must be filled on complete parse");
let path = req.path.expect("path must be filled on complete parse");
write_dict_req(method, path, &normalize_headers(req.headers))
}
Response => {
let mut resp = httparse::Response::new(&mut headers);
let mut buf: Vec<u8> = vec![];
match read_till_end_of_header(&mut buf, stdin.lock()) {
Some(()) => match resp.parse(&buf) {
Ok(httparse::Status::Complete(_body_start)) => {}
Ok(httparse::Status::Partial) => {
die_expected_error("read-http", "httparse should have gotten a full header")
}
Err(err) => die_expected_error(
"read-http",
format!("httparse response parsing failed: {:#?}", err),
),
},
None => die_expected_error(
"read-http",
format!("httparse end of stdin reached before able to parse response headers"),
),
}
let code = resp.code.expect("code must be filled on complete parse");
let reason = resp
.reason
.expect("reason must be filled on complete parse");
write_dict_resp(code, reason, &normalize_headers(resp.headers))
}
}
}
fn write_dict_req<'a, 'buf>(
method: &'buf str,
path: &'buf str,
headers: &'a HashMap<String, U<'a>>,
) -> std::io::Result<()> {
let mut http = vec![("method", U::Text(method)), ("path", U::Text(path))]
.into_iter()
.collect();
write_dict(http, headers)
}
fn write_dict_resp<'a, 'buf>(
code: u16,
reason: &'buf str,
headers: &'a HashMap<String, U<'a>>,
) -> std::io::Result<()> {
let mut http = vec![
("status", U::N6(code as u64)),
("status-text", U::Text(reason)),
]
.into_iter()
.collect();
write_dict(http, headers)
}
fn write_dict<'buf, 'a>(
mut http: HashMap<&str, U<'a>>,
headers: &'a HashMap<String, U<'a>>,
) -> std::io::Result<()> {
match http.insert(
"headers",
U::Record(
headers
.iter()
.map(|(k, v)| (k.as_str(), v.clone()))
.collect(),
),
) {
None => (),
Some(_) => panic!("read-http: headers already in dict"),
};
netencode::encode(&mut std::io::stdout(), &U::Record(http))?;
Ok(())
}
// iter helper
struct Chunkyboi<T> {
inner: T,
buf: Vec<u8>,
}
impl<R: Read> Chunkyboi<R> {
fn new(inner: R, chunksize: usize) -> Self {
let buf = vec![0; chunksize];
Chunkyboi { inner, buf }
}
}
impl<R: Read> Iterator for Chunkyboi<R> {
type Item = std::io::Result<Vec<u8>>;
fn next(&mut self) -> Option<std::io::Result<Vec<u8>>> {
match self.inner.read(&mut self.buf) {
Ok(0) => None,
Ok(read) => {
// clone a new buffer so we can reuse the internal one
Some(Ok(self.buf[..read].to_owned()))
}
Err(err) => Some(Err(err)),
}
}
}
