Add :shutdown() method for ending the TLS session before :close()

src/luasocket/usocket.c

@@ -82,7 +82,6 @@ int socket_close(void) {
 \*-------------------------------------------------------------------------*/
 void socket_destroy(p_socket ps) {
     if (*ps != SOCKET_INVALID) {
-        socket_setblocking(ps);
         close(*ps);
         *ps = SOCKET_INVALID;
     }

src/ssl.c

@@ -86,7 +86,8 @@ static int meth_destroy(lua_State *L)
 {
   p_ssl ssl = (p_ssl)luaL_checkudata(L, 1, "SSL:Connection");
   if (ssl->state == LSEC_STATE_CONNECTED) {
-    socket_setblocking(&ssl->sock);
+    if (!ssl->shutdown)
+      socket_setblocking(&ssl->sock);
     SSL_shutdown(ssl->ssl);
   }
   if (ssl->sock != SOCKET_INVALID) {
@@ -304,6 +305,7 @@ static int meth_create(lua_State *L)
     return luaL_argerror(L, 1, "invalid context");
   }
   ssl->state = LSEC_STATE_NEW;
+  ssl->shutdown = 0;
   SSL_set_fd(ssl->ssl, (int)SOCKET_INVALID);
   SSL_set_mode(ssl->ssl, SSL_MODE_ENABLE_PARTIAL_WRITE | 
     SSL_MODE_ACCEPT_MOVING_WRITE_BUFFER);
@@ -339,6 +341,56 @@ static int meth_receive(lua_State *L) {
   return buffer_meth_receive(L, &ssl->buf);
 }
 
+/**
+ * SSL shutdown function
+ */
+static int meth_shutdown(lua_State *L) {
+  p_ssl ssl = (p_ssl)luaL_checkudata(L, 1, "SSL:Connection");
+  int err;
+  p_timeout tm = timeout_markstart(&ssl->tm);
+
+  ssl->shutdown = 1;
+  if (ssl->state == LSEC_STATE_CLOSED) {
+    lua_pushboolean(L, 1);
+    return 1;
+  }
+
+  err = SSL_shutdown(ssl->ssl);
+  switch (err) {
+  case 0:
+    lua_pushboolean(L, 0);
+    lua_pushnil(L);
+    return 2;
+  case 1:
+    lua_pushboolean(L, 1);
+    lua_pushnil(L);
+    ssl->state = LSEC_STATE_CLOSED;
+    return 2;
+  case -1:
+    lua_pushboolean(L, 0);
+    ssl->error = SSL_get_error(ssl->ssl, err);
+    switch (ssl->error) {
+    case SSL_ERROR_WANT_READ:
+      err = socket_waitfd(&ssl->sock, WAITFD_R, tm);
+      lua_pushstring(L, ssl_ioerror((void *)ssl, err == IO_TIMEOUT ? LSEC_IO_SSL : err));
+      break;
+    case SSL_ERROR_WANT_WRITE:
+      err = socket_waitfd(&ssl->sock, WAITFD_W, tm);
+      lua_pushstring(L, ssl_ioerror((void *)ssl, err == IO_TIMEOUT ? LSEC_IO_SSL : err));
+      break;
+    case SSL_ERROR_SYSCALL:
+      if (ERR_peek_error())
+        ssl->error = SSL_ERROR_SSL;
+      lua_pushstring(L, ssl_ioerror((void *)ssl, LSEC_IO_SSL));
+      break;
+    default:
+      lua_pushstring(L, ssl_ioerror((void *)ssl, LSEC_IO_SSL));
+      break;
+    }
+    return 2;
+  }
+}
+
 /**
  * Get the buffer's statistics.
  */
@@ -990,6 +1042,7 @@ static int meth_tlsa(lua_State *L)
  */
 static luaL_Reg methods[] = {
   {"close",               meth_close},
+  {"shutdown",            meth_shutdown},
   {"getalpn",             meth_getalpn},
   {"getfd",               meth_getfd},
   {"getfinished",         meth_getfinished},

src/ssl.h

@@ -32,6 +32,7 @@ typedef struct t_ssl_ {
   t_timeout tm;
   SSL *ssl;
   int state;
+  int shutdown;
   int error;
 } t_ssl;
 typedef t_ssl* p_ssl;