karyons jsonrpc implementation

1 files changed, 63 insertions, 0 deletions

diff --git a/jsonrpc/src/utils.rs b/jsonrpc/src/utils.rs
new file mode 100644
index 0000000..1f21b7a
--- /dev/null
+++ b/jsonrpc/src/utils.rs
@@ -0,0 +1,63 @@
+use memchr::memchr;
+
+use karyons_net::Conn;
+
+use crate::{Error, Result};
+
+const DEFAULT_MSG_SIZE: usize = 1024;
+const MAX_ALLOWED_MSG_SIZE: usize = 1024 * 1024; // 1MB
+
+// TODO: Add unit tests for these functions.
+
+/// Read all bytes into `buffer` until the `0x0` byte or EOF is
+/// reached.
+///
+/// If successful, this function will return the total number of bytes read.
+pub async fn read_until(conn: &Conn, buffer: &mut Vec<u8>) -> Result<usize> {
+    let delim = b'\0';
+
+    let mut read = 0;
+
+    loop {
+        let mut tmp_buf = [0; DEFAULT_MSG_SIZE];
+        let n = conn.read(&mut tmp_buf).await?;
+        if n == 0 {
+            return Err(Error::IO(std::io::ErrorKind::UnexpectedEof.into()));
+        }
+
+        match memchr(delim, &tmp_buf) {
+            Some(i) => {
+                buffer.extend_from_slice(&tmp_buf[..i]);
+                read += i;
+                break;
+            }
+            None => {
+                buffer.extend_from_slice(&tmp_buf);
+                read += tmp_buf.len();
+            }
+        }
+
+        if buffer.len() == MAX_ALLOWED_MSG_SIZE {
+            return Err(Error::InvalidMsg(
+                "Message exceeds the maximum allowed size",
+            ));
+        }
+    }
+
+    Ok(read)
+}
+
+/// Writes an entire buffer into the given connection.
+pub async fn write_all(conn: &Conn, mut buf: &[u8]) -> Result<()> {
+    while !buf.is_empty() {
+        let n = conn.write(buf).await?;
+        let (_, rest) = std::mem::take(&mut buf).split_at(n);
+        buf = rest;
+
+        if n == 0 {
+            return Err(Error::IO(std::io::ErrorKind::UnexpectedEof.into()));
+        }
+    }
+
+    Ok(())
+}