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135 lines
2.6 KiB
Go
135 lines
2.6 KiB
Go
/*
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Copyright 2022 CAcert Inc.
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SPDX-License-Identifier: Apache-2.0
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Licensed under the Apache License, Version 2.0 (the "License");
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you may not use this file except in compliance with the License.
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You may obtain a copy of the License at
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http://www.apache.org/licenses/LICENSE-2.0
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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,
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WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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See the License for the specific language governing permissions and
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limitations under the License.
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*/
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// Package seriallink provides a handler for the serial connection of the signer machine.
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package seriallink
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import (
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"fmt"
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"time"
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"github.com/justincpresley/go-cobs"
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"github.com/tarm/serial"
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"git.cacert.org/cacert-gosigner/pkg/config"
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"git.cacert.org/cacert-gosigner/pkg/protocol"
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)
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type Handler struct {
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protocolHandler protocol.Handler
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config *serial.Config
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port *serial.Port
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}
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func (h *Handler) setupConnection() error {
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s, err := serial.OpenPort(h.config)
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if err != nil {
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return fmt.Errorf("could not open serial port: %w", err)
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}
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h.port = s
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return nil
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}
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func (h *Handler) Close() error {
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err := h.port.Close()
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if err != nil {
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return fmt.Errorf("could not close serial port: %w", err)
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}
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return nil
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}
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const cobsDelimiter = 0x00
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func (h *Handler) Run() error {
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const (
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bufferSize = 1024 * 1024
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readInterval = 50 * time.Millisecond
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)
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errors := make(chan error)
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cobsConfig := cobs.Config{SpecialByte: cobsDelimiter, Delimiter: true, EndingSave: true}
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go func() {
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buf := make([]byte, bufferSize)
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for {
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count, err := h.port.Read(buf)
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if err != nil {
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errors <- err
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return
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}
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if count == 0 {
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time.Sleep(readInterval)
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continue
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}
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err = cobs.Verify(buf[:count], cobsConfig)
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if err != nil {
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errors <- err
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return
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}
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// perform COBS decoding
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decoded := cobs.Decode(buf[:count], cobsConfig)
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msg, err := h.protocolHandler.HandleFrame(decoded)
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if err != nil {
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errors <- err
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return
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}
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// perform COBS encoding
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encoded := cobs.Encode(msg, cobsConfig)
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_, err = h.port.Write(encoded)
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if err != nil {
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errors <- err
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return
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}
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}
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}()
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err := <-errors
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if err != nil {
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return fmt.Errorf("error from handler loop: %w", err)
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}
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return nil
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}
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func New(cfg *config.Serial, protocolHandler protocol.Handler) (*Handler, error) {
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h := &Handler{protocolHandler: protocolHandler}
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h.config = &serial.Config{Name: cfg.Device, Baud: cfg.Baud, ReadTimeout: cfg.Timeout}
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err := h.setupConnection()
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if err != nil {
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return nil, err
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}
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return h, nil
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}
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