82 lines
2.1 KiB
Go
82 lines
2.1 KiB
Go
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package checkrunner
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import (
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"context"
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"fmt"
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"net"
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"os"
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"time"
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"golang.org/x/net/icmp"
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"golang.org/x/net/ipv4"
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)
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// ICMPEcho sends up to `count` ICMP echo requests to host and reports
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// success if at least one echo reply is received before timeout. Uses a
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// raw ICMP socket (ip4:icmp), which requires either running as root or
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// (on Linux, as deployed here) the CAP_NET_RAW capability — see the
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// validator-agent and prober systemd units.
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func ICMPEcho(host string, count int, timeout time.Duration) func(ctx context.Context) Result {
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return run("icmp", host, func(ctx context.Context) error {
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conn, err := icmp.ListenPacket("ip4:icmp", "0.0.0.0")
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if err != nil {
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return fmt.Errorf("open icmp socket (needs CAP_NET_RAW or root): %w", err)
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}
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defer conn.Close()
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dst, err := net.ResolveIPAddr("ip4", host)
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if err != nil {
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return fmt.Errorf("resolve %s: %w", host, err)
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}
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id := os.Getpid() & 0xffff
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var lastErr error
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for seq := 1; seq <= count; seq++ {
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if err := ctx.Err(); err != nil {
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return err
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}
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msg := icmp.Message{
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Type: ipv4.ICMPTypeEcho,
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Code: 0,
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Body: &icmp.Echo{
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ID: id,
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Seq: seq,
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Data: []byte("cloud-ip-validator"),
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},
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}
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wb, err := msg.Marshal(nil)
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if err != nil {
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return fmt.Errorf("marshal echo request: %w", err)
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}
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if _, err := conn.WriteTo(wb, dst); err != nil {
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lastErr = fmt.Errorf("write echo request: %w", err)
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continue
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}
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perAttempt := timeout / time.Duration(count)
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if perAttempt <= 0 {
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perAttempt = timeout
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}
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conn.SetReadDeadline(time.Now().Add(perAttempt))
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rb := make([]byte, 1500)
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n, _, err := conn.ReadFrom(rb)
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if err != nil {
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lastErr = fmt.Errorf("read echo reply: %w", err)
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continue
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}
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rm, err := icmp.ParseMessage(1 /* protocolICMP */, rb[:n])
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if err != nil {
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lastErr = fmt.Errorf("parse reply: %w", err)
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continue
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}
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if rm.Type == ipv4.ICMPTypeEchoReply {
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return nil
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}
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lastErr = fmt.Errorf("unexpected icmp type %v", rm.Type)
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}
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if lastErr == nil {
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lastErr = fmt.Errorf("no reply received")
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}
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return lastErr
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})
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}
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