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-rw-r--r--users/Profpatsch/read-http.rs249
1 files changed, 249 insertions, 0 deletions
diff --git a/users/Profpatsch/read-http.rs b/users/Profpatsch/read-http.rs
new file mode 100644
index 000000000000..efaded87e6cd
--- /dev/null
+++ b/users/Profpatsch/read-http.rs
@@ -0,0 +1,249 @@
+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)),
+        }
+    }
+}