Pierre-Olivier Mercier
d57c08a6c4
Probe the configured Ethernet interface (default eth0, overridable via -ethernet-interface) at startup. If no DHCP-assigned IPv4 is present, start the wpa_supplicant service so the WiFi backend has something to talk to; otherwise leave it alone and rely on the wired uplink.
54 lines
1.6 KiB
Go
54 lines
1.6 KiB
Go
package app
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import (
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"fmt"
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"log"
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"os/exec"
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"strings"
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)
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// hasDHCPAddress reports whether iface holds an IPv4 address that ip(8) marks
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// as "dynamic" — the flag set on addresses with a finite valid_lft, which is
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// how DHCP-assigned leases appear (static addresses are "permanent").
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func hasDHCPAddress(iface string) (bool, error) {
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out, err := exec.Command("ip", "-4", "-o", "addr", "show", "dev", iface).Output()
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if err != nil {
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return false, fmt.Errorf("ip addr show %s: %w", iface, err)
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}
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for _, line := range strings.Split(string(out), "\n") {
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fields := strings.Fields(line)
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hasInet := false
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hasDynamic := false
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for _, f := range fields {
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switch f {
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case "inet":
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hasInet = true
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case "dynamic":
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hasDynamic = true
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}
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}
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if hasInet && hasDynamic {
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return true, nil
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}
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}
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return false, nil
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}
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// ensureUplink boots the WiFi uplink only if Ethernet is not already providing
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// connectivity: when iface has no DHCP-assigned IPv4, start wpa_supplicant so
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// the WiFi backend can take over.
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func ensureUplink(iface string) {
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has, err := hasDHCPAddress(iface)
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if err != nil {
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log.Printf("Could not probe %s for DHCP address (%v); starting wpa_supplicant as fallback", iface, err)
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} else if has {
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log.Printf("DHCP address present on %s, leaving wpa_supplicant alone", iface)
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return
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} else {
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log.Printf("No DHCP address on %s, starting wpa_supplicant", iface)
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}
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if out, err := exec.Command("systemctl", "start", "wpa_supplicant").CombinedOutput(); err != nil {
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log.Printf("Failed to start wpa_supplicant: %v: %s", err, strings.TrimSpace(string(out)))
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}
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}
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