merge impl-v2: server

server/src/web_util.rs

@@ -0,0 +1,43 @@
+use std::io::Read;
+
+use rouille;
+use serde;
+use serde_json;
+
+static MAX_BODY_SIZE: usize = 100 * 1024 * 1024; // 100 MiB
+
+/// Pulls text that may be JSON out of a Rouille Request object.
+///
+/// Doesn't do any actual parsing -- all this method does is verify the content
+/// type of the request and read the request's body.
+fn read_json_text(request: &rouille::Request) -> Option<String> {
+    // Bail out if the request body isn't marked as JSON
+    let content_type = request.header("Content-Type")?;
+
+    if !content_type.starts_with("application/json") {
+        return None;
+    }
+
+    let body = request.data()?;
+
+    // Allocate a buffer and read up to MAX_BODY_SIZE+1 bytes into it.
+    let mut out = Vec::new();
+    body.take(MAX_BODY_SIZE.saturating_add(1) as u64).read_to_end(&mut out).ok()?;
+
+    // If the body was too big (MAX_BODY_SIZE+1), we abort instead of trying to
+    // process it.
+    if out.len() > MAX_BODY_SIZE {
+        return None;
+    }
+
+    String::from_utf8(out).ok()
+}
+
+/// Reads the body out of a Rouille Request and attempts to turn it into JSON.
+pub fn read_json<T>(request: &rouille::Request) -> Option<T>
+where
+    T: serde::de::DeserializeOwned,
+{
+    let body = read_json_text(&request)?;
+    serde_json::from_str(&body).ok()?
+}