66 lines
1.5 KiB
Go
66 lines
1.5 KiB
Go
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package diagnostic
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import (
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"bufio"
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"bytes"
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"fmt"
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"io"
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"os/exec"
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)
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type DecodeLineFunc func(text string) (*Hop, error)
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func decodeNetworkOutputToFile(command *exec.Cmd, fn DecodeLineFunc) ([]*Hop, string, error) {
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stdout, err := command.StdoutPipe()
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if err != nil {
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return nil, "", fmt.Errorf("error piping traceroute's output: %w", err)
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}
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if err := command.Start(); err != nil {
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return nil, "", fmt.Errorf("error starting traceroute: %w", err)
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}
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// Tee the output to a string to have the raw information
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// in case the decode call fails
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// This error is handled only after the Wait call below returns
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// otherwise the process can become a zombie
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buf := bytes.NewBuffer([]byte{})
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tee := io.TeeReader(stdout, buf)
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hops, err := Decode(tee, fn)
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if werr := command.Wait(); werr != nil {
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return nil, "", fmt.Errorf("error finishing traceroute: %w", werr)
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}
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if err != nil {
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// consume all output to have available in buf
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io.ReadAll(tee)
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// This is already a TracerouteError no need to wrap it
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return nil, buf.String(), err
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}
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return hops, "", nil
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}
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func Decode(reader io.Reader, fn DecodeLineFunc) ([]*Hop, error) {
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scanner := bufio.NewScanner(reader)
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scanner.Split(bufio.ScanLines)
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var hops []*Hop
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for scanner.Scan() {
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text := scanner.Text()
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hop, err := fn(text)
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if err != nil {
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return nil, fmt.Errorf("error decoding output line: %w", err)
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}
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hops = append(hops, hop)
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}
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if scanner.Err() != nil {
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return nil, fmt.Errorf("scanner reported an error: %w", scanner.Err())
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}
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return hops, nil
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}
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