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[wifi] Also require netif_is_link_up for dhcp_renew guard

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DHCP_STATE_BOUND alone is insufficient — during reconnection, DHCP
can remain BOUND from a previous connection while the link is down
(wifi_disconnect_() doesn't stop DHCP). Both conditions are needed:
DHCP must be BOUND and the interface must have link.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
This commit is contained in:
J. Nick Koston
2026-02-13 20:04:51 -07:00
parent c53d50b6cf
commit 8abb472c3a
1 changed files with 9 additions and 5 deletions
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14
esphome/components/wifi/wifi_component_esp8266.cpp
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@@ -226,12 +226,16 @@ bool WiFiComponent::wifi_apply_hostname_() {
intf->hostname = wifi_station_get_hostname();
#endif
struct dhcp *dhcp_data = netif_dhcp_data(intf);
if (dhcp_data != nullptr && dhcp_data->state == DHCP_STATE_BOUND) {
if (dhcp_data != nullptr && dhcp_data->state == DHCP_STATE_BOUND && netif_is_link_up(intf)) {
// Renew already-bound DHCP leases to inform server of hostname change.
// Only attempt when DHCP is BOUND — calling dhcp_renew() in any other
// state corrupts lwIP's DHCP state machine (it unconditionally sets state
// to RENEWING before attempting to send, and never rolls back on failure).
// This causes dhcp_network_changed() to call dhcp_reboot() instead of
// Both conditions are required:
// - DHCP must be BOUND (have an active lease to renew)
// - Interface must have link (able to send packets)
// During reconnection, DHCP can remain BOUND from a previous connection
// while the link is down. Calling dhcp_renew() without link corrupts
// lwIP's DHCP state machine (it unconditionally sets state to RENEWING
// before attempting to send, and never rolls back on failure). This
// causes dhcp_network_changed() to call dhcp_reboot() instead of
// dhcp_discover() when WiFi later connects, sending a bogus DHCP REQUEST
// for IP 0.0.0.0 that can put some routers into a persistent bad state.
err_t lwipret = dhcp_renew(intf);