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55 lines
1.6 KiB
55 lines
1.6 KiB
// Copyright 2021 The Pigweed Authors
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//
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// Licensed under the Apache License, Version 2.0 (the "License"); you may not
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// use this file except in compliance with the License. You may obtain a copy of
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// the License at
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//
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// https://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
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// WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
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// License for the specific language governing permissions and limitations under
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// the License.
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#include "pw_hdlc/wire_packet_parser.h"
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#include "pw_bytes/endian.h"
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#include "pw_checksum/crc32.h"
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#include "pw_hdlc/decoder.h"
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#include "pw_hdlc/internal/protocol.h"
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namespace pw::hdlc {
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bool WirePacketParser::Parse(ConstByteSpan packet) {
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if (packet.size_bytes() < Frame::kMinSizeBytes) {
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return false;
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}
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if (packet.front() != kFlag || packet.back() != kFlag) {
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return false;
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}
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// Partially decode into a buffer with space only for the address and control
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// fields of the frame. The decoder will verify the frame's FCS field.
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std::array<std::byte, 16> buffer = {};
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Decoder decoder(buffer);
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Status status = Status::Unknown();
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decoder.Process(packet, [&status](const Result<Frame>& result) {
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status = result.status();
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});
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Result<Frame> result = Frame::Parse(buffer);
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if (!result.ok()) {
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return false;
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}
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address_ = result.value().address();
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// RESOURCE_EXHAUSTED is expected as the buffer is too small for the packet.
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return status.ok() || status.IsResourceExhausted();
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}
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} // namespace pw::hdlc
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