Add _ssl.MemoryBIO (#1378)

* Add _ssl.MemoryBIO

* Add some tests

Author: slozier

Src/IronPython.Modules/_ssl.cs

@@ -6,6 +6,7 @@
 
 using System;
 using System.Collections.Generic;
+using System.Diagnostics;
 using System.Globalization;
 using System.IO;
 using System.Linq;
@@ -610,6 +611,83 @@ public int write(CodeContext/*!*/ context, Bytes data) {
             }
         }
 
+#nullable enable
+
+        [PythonType]
+        public class MemoryBIO {
+            private bool _write_eof;
+
+            public bool eof { get; private set; }
+            public int pending { get; private set; }
+
+            private Bytes? buf;
+            private Queue<Bytes> queue = new Queue<Bytes>();
+
+            public MemoryBIO() { }
+
+            public Bytes read(int size = -1) {
+                if (size == 0 || eof) {
+                    return Bytes.Empty;
+                }
+                if (size == -1 || size > pending) {
+                    size = pending;
+                }
+
+                byte[] res = new byte[size];
+                var resSpan = res.AsSpan();
+
+                if (buf is not null) {
+                    var span = buf.AsSpan();
+                    var length = resSpan.Length;
+                    if (length < span.Length) {
+                        buf = Bytes.Make(span.Slice(length).ToArray());
+                        span = span.Slice(0, length);
+                    }
+                    else {
+                        buf = null;
+                    }
+                    span.CopyTo(resSpan);
+                    resSpan = resSpan.Slice(span.Length);
+                }
+
+                while (resSpan.Length > 0) {
+                    Debug.Assert(buf is null && queue.Count > 0);
+                    var span = queue.Dequeue().AsSpan();
+                    var length = resSpan.Length;
+                    if (length < span.Length) {
+                        buf = Bytes.Make(span.Slice(length).ToArray());
+                        span = span.Slice(0, length);
+                    }
+                    span.CopyTo(resSpan);
+                    resSpan = resSpan.Slice(span.Length);
+                }
+
+                pending -= size;
+                if (_write_eof && pending == 0) eof = true;
+                return Bytes.Make(res);
+            }
+
+            public int write(CodeContext context, [NotNull] IBufferProtocol b) {
+                if (_write_eof) throw PythonExceptions.CreateThrowable(SSLError(context), "cannot write() after write_eof()");
+
+                if (b is not Bytes bytes) {
+                    using var buffer = b.GetBuffer();
+                    bytes = Bytes.Make(buffer.ToArray());
+                }
+                if (bytes.Count == 0) return 0;
+                queue.Enqueue(bytes);
+                pending += bytes.Count;
+                return bytes.Count;
+            }
+
+            public void write_eof() {
+                _write_eof = true;
+                if (pending == 0) eof = true;
+            }
+        }
+
+#nullable restore
+
         public static object txt2obj(CodeContext context, string txt, bool name = false) {
             Asn1Object obj = null;
             if (name) {

Tests/modules/network_related/test__ssl.py

@@ -9,6 +9,7 @@
 import _ssl
 import os
 import socket
+import sys
 import unittest
 
 from iptest import IronPythonTestCase, is_cli, is_netcoreapp, retryOnFailure, run_test, skipUnlessIronPython
@@ -269,4 +270,69 @@ def test_cert_date_locale(self):
         finally:
             System.Threading.Thread.CurrentThread.CurrentCulture = culture
 
+import _ssl as ssl
+
+# These come from the 3.5 stdlib and can eventually be removed
+@unittest.skipUnless(is_cli or sys.version_info >= (3,5), "not in CPython 3.4")
+class MemoryBIOTests(unittest.TestCase):
+    def test_read_write(self):
+        bio = ssl.MemoryBIO()
+        bio.write(b'foo')
+        self.assertEqual(bio.read(), b'foo')
+        self.assertEqual(bio.read(), b'')
+        bio.write(b'foo')
+        bio.write(b'bar')
+        self.assertEqual(bio.read(), b'foobar')
+        self.assertEqual(bio.read(), b'')
+        bio.write(b'baz')
+        self.assertEqual(bio.read(2), b'ba')
+        self.assertEqual(bio.read(1), b'z')
+        self.assertEqual(bio.read(1), b'')
+
+    def test_eof(self):
+        bio = ssl.MemoryBIO()
+        self.assertFalse(bio.eof)
+        self.assertEqual(bio.read(), b'')
+        self.assertFalse(bio.eof)
+        bio.write(b'foo')
+        self.assertFalse(bio.eof)
+        bio.write_eof()
+        self.assertFalse(bio.eof)
+        self.assertEqual(bio.read(2), b'fo')
+        self.assertFalse(bio.eof)
+        self.assertEqual(bio.read(1), b'o')
+        self.assertTrue(bio.eof)
+        self.assertEqual(bio.read(), b'')
+        self.assertTrue(bio.eof)
+
+    def test_pending(self):
+        bio = ssl.MemoryBIO()
+        self.assertEqual(bio.pending, 0)
+        bio.write(b'foo')
+        self.assertEqual(bio.pending, 3)
+        for i in range(3):
+            bio.read(1)
+            self.assertEqual(bio.pending, 3-i-1)
+        for i in range(3):
+            bio.write(b'x')
+            self.assertEqual(bio.pending, i+1)
+        bio.read()
+        self.assertEqual(bio.pending, 0)
+
+    def test_buffer_types(self):
+        bio = ssl.MemoryBIO()
+        bio.write(b'foo')
+        self.assertEqual(bio.read(), b'foo')
+        bio.write(bytearray(b'bar'))
+        self.assertEqual(bio.read(), b'bar')
+        bio.write(memoryview(b'baz'))
+        self.assertEqual(bio.read(), b'baz')
+
+    def test_error_types(self):
+        bio = ssl.MemoryBIO()
+        self.assertRaises(TypeError, bio.write, 'foo')
+        self.assertRaises(TypeError, bio.write, None)
+        self.assertRaises(TypeError, bio.write, True)
+        self.assertRaises(TypeError, bio.write, 1)
+
 run_test(__name__)