Expand Shadowsocks runtime compatibility

third_party/rustls-fork-shadow-tls/src/rand.rs

@@ -0,0 +1,30 @@
+use crate::msgs::codec;
+/// The single place where we generate random material
+/// for our own use.  These functions never fail,
+/// they panic on error.
+use ring::rand::{SecureRandom, SystemRandom};
+
+/// Fill the whole slice with random material.
+pub(crate) fn fill_random(bytes: &mut [u8]) -> Result<(), GetRandomFailed> {
+    SystemRandom::new()
+        .fill(bytes)
+        .map_err(|_| GetRandomFailed)
+}
+
+/// Make a Vec<u8> of the given size
+/// containing random material.
+pub(crate) fn random_vec(len: usize) -> Result<Vec<u8>, GetRandomFailed> {
+    let mut v = vec![0; len];
+    fill_random(&mut v)?;
+    Ok(v)
+}
+
+/// Return a uniformly random u32.
+pub(crate) fn random_u32() -> Result<u32, GetRandomFailed> {
+    let mut buf = [0u8; 4];
+    fill_random(&mut buf)?;
+    codec::decode_u32(&buf).ok_or(GetRandomFailed)
+}
+
+#[derive(Debug)]
+pub struct GetRandomFailed;