1 files changed, 128 insertions, 0 deletions
diff --git a/contrib/epee/src/levin_base.cpp b/contrib/epee/src/levin_base.cpp
new file mode 100644
index 000000000..ff845e2a7
--- /dev/null
+++ b/contrib/epee/src/levin_base.cpp
@@ -0,0 +1,128 @@
+// Copyright (c) 2019, The Monero Project
+//
+// All rights reserved.
+//
+// Redistribution and use in source and binary forms, with or without modification, are
+// permitted provided that the following conditions are met:
+//
+// 1. Redistributions of source code must retain the above copyright notice, this list of
+//    conditions and the following disclaimer.
+//
+// 2. Redistributions in binary form must reproduce the above copyright notice, this list
+//    of conditions and the following disclaimer in the documentation and/or other
+//    materials provided with the distribution.
+//
+// 3. Neither the name of the copyright holder nor the names of its contributors may be
+//    used to endorse or promote products derived from this software without specific
+//    prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY
+// EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
+// MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL
+// THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
+// PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+// INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
+// STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF
+// THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+#include "net/levin_base.h"
+
+#include "int-util.h"
+
+namespace epee
+{
+namespace levin
+{
+  bucket_head2 make_header(uint32_t command, uint64_t msg_size, uint32_t flags, bool expect_response) noexcept
+  {
+    bucket_head2 head = {0};
+    head.m_signature = SWAP64LE(LEVIN_SIGNATURE);
+    head.m_have_to_return_data = expect_response;
+    head.m_cb = SWAP64LE(msg_size);
+
+    head.m_command = SWAP32LE(command);
+    head.m_protocol_version = SWAP32LE(LEVIN_PROTOCOL_VER_1);
+    head.m_flags = SWAP32LE(flags);
+    return head;
+  }
+
+  byte_slice make_notify(int command, epee::span<const std::uint8_t> payload)
+  {
+    const bucket_head2 head = make_header(command, payload.size(), LEVIN_PACKET_REQUEST, false);
+    return byte_slice{epee::as_byte_span(head), payload};
+  }
+
+  byte_slice make_noise_notify(const std::size_t noise_bytes)
+  {
+    static constexpr const std::uint32_t flags =
+        LEVIN_PACKET_BEGIN | LEVIN_PACKET_END;
+
+    if (noise_bytes < sizeof(bucket_head2))
+      return nullptr;
+
+    std::string buffer(noise_bytes, char(0));
+    const bucket_head2 head = make_header(0, noise_bytes - sizeof(bucket_head2), flags, false);
+    std::memcpy(std::addressof(buffer[0]), std::addressof(head), sizeof(head));
+
+    return byte_slice{std::move(buffer)};
+  }
+
+  byte_slice make_fragmented_notify(const byte_slice& noise_message, int command, epee::span<const std::uint8_t> payload)
+  {
+    const size_t noise_size = noise_message.size();
+    if (noise_size < sizeof(bucket_head2) * 2)
+      return nullptr;
+
+    if (payload.size() <= noise_size - sizeof(bucket_head2))
+    {
+      /* The entire message can be sent at once, and the levin binary parser
+         will ignore extra bytes. So just pad with zeroes and otherwise send
+         a "normal", not fragmented message. */
+      const size_t padding = noise_size - sizeof(bucket_head2) - payload.size();
+      const span<const uint8_t> padding_bytes{noise_message.end() - padding, padding};
+
+      const bucket_head2 head = make_header(command, noise_size - sizeof(bucket_head2), LEVIN_PACKET_REQUEST, false);
+      return byte_slice{as_byte_span(head), payload, padding_bytes};
+    }
+
+    // fragment message
+    const size_t payload_space = noise_size - sizeof(bucket_head2);
+    const size_t expected_fragments = ((payload.size() - 2) / payload_space) + 1;
+
+    std::string buffer{};
+    buffer.reserve((expected_fragments + 1) * noise_size); // +1 here overselects for internal bucket_head2 value
+
+    bucket_head2 head = make_header(0, noise_size - sizeof(bucket_head2), LEVIN_PACKET_BEGIN, false);
+    buffer.append(reinterpret_cast<const char*>(&head), sizeof(head));
+
+    head.m_command = command;
+    head.m_flags = LEVIN_PACKET_REQUEST;
+    head.m_cb = payload.size();
+    buffer.append(reinterpret_cast<const char*>(&head), sizeof(head));
+
+    size_t copy_size = payload.remove_prefix(payload_space - sizeof(bucket_head2));
+    buffer.append(reinterpret_cast<const char*>(payload.data()) - copy_size, copy_size);
+
+    head.m_command = 0;
+    head.m_flags = 0;
+    head.m_cb = noise_size - sizeof(bucket_head2);
+
+    while (!payload.empty())
+    {
+      copy_size = payload.remove_prefix(payload_space);
+
+      if (payload.empty())
+        head.m_flags = LEVIN_PACKET_END;
+
+      buffer.append(reinterpret_cast<const char*>(&head), sizeof(head));
+      buffer.append(reinterpret_cast<const char*>(payload.data()) - copy_size, copy_size);
+    }
+
+    const size_t padding = noise_size - copy_size - sizeof(bucket_head2);
+    buffer.append(reinterpret_cast<const char*>(noise_message.end()) - padding, padding);
+
+    return byte_slice{std::move(buffer)};
+  }
+} // levin
+} // epee