std.crypto.Tls: parse the ServerHello handshake

lib/std/net.zig

@@ -1672,6 +1672,28 @@ pub const Stream = struct {
         }
     }
 
+    /// Returns the number of bytes read. If the number read is smaller than
+    /// `buffer.len`, it means the stream reached the end. Reaching the end of
+    /// a stream is not an error condition.
+    pub fn readAll(s: Stream, buffer: []u8) ReadError!usize {
+        return readAtLeast(s, buffer, buffer.len);
+    }
+
+    /// Returns the number of bytes read, calling the underlying read function
+    /// multiple times until at least the buffer has at least `len` bytes
+    /// filled. If the number read is less than `len` it means the stream
+    /// reached the end. Reaching the end of the stream is not an error
+    /// condition.
+    pub fn readAtLeast(s: Stream, buffer: []u8, len: usize) ReadError!usize {
+        var index: usize = 0;
+        while (index < len) {
+            const amt = try s.read(buffer[index..]);
+            if (amt == 0) break;
+            index += amt;
+        }
+        return index;
+    }
+
     /// TODO in evented I/O mode, this implementation incorrectly uses the event loop's
     /// file system thread instead of non-blocking. It needs to be reworked to properly
     /// use non-blocking I/O.