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-rw-r--r--src/plugins/nat/lib/nat_inlines.h66
1 files changed, 66 insertions, 0 deletions
diff --git a/src/plugins/nat/lib/nat_inlines.h b/src/plugins/nat/lib/nat_inlines.h
new file mode 100644
index 00000000000..fc8e160bb2b
--- /dev/null
+++ b/src/plugins/nat/lib/nat_inlines.h
@@ -0,0 +1,66 @@
+/*
+ * Copyright (c) 2020 Cisco and/or its affiliates.
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at:
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include <vnet/tcp/tcp_packet.h>
+#include <vnet/ip/ip4_packet.h>
+
+always_inline void
+mss_clamping (u16 mss_clamping, tcp_header_t * tcp, ip_csum_t * sum)
+{
+ u8 *data;
+ u8 opt_len, opts_len, kind;
+ u16 mss;
+
+ if (!(mss_clamping && tcp_syn (tcp)))
+ return;
+
+ opts_len = (tcp_doff (tcp) << 2) - sizeof (tcp_header_t);
+ data = (u8 *) (tcp + 1);
+ for (; opts_len > 0; opts_len -= opt_len, data += opt_len)
+ {
+ kind = data[0];
+
+ if (kind == TCP_OPTION_EOL)
+ break;
+ else if (kind == TCP_OPTION_NOOP)
+ {
+ opt_len = 1;
+ continue;
+ }
+ else
+ {
+ if (opts_len < 2)
+ return;
+ opt_len = data[1];
+
+ if (opt_len < 2 || opt_len > opts_len)
+ return;
+ }
+
+ if (kind == TCP_OPTION_MSS)
+ {
+ mss = *(u16 *) (data + 2);
+ if (clib_net_to_host_u16 (mss) > mss_clamping)
+ {
+ u16 mss_value_net = clib_host_to_net_u16(mss_clamping);
+ *sum =
+ ip_csum_update (*sum, mss, mss_value_net, ip4_header_t,
+ length);
+ clib_memcpy_fast (data + 2, &mss_value_net, 2);
+ }
+ return;
+ }
+ }
+}