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[dhcp4relay] Fix bug: DHCP relay broken after "config vrf bind <Vlan> <Vrf>" (socket not rebound to new VRF) #104

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Merged
Xichen96 merged 2 commits into from
Apr 28, 2026
+16 −11
Merged

[dhcp4relay] Fix bug: DHCP relay broken after "config vrf bind <Vlan> <Vrf>" (socket not rebound to new VRF) #104

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20f28b1
[dhcp4relay] Fix bug: DHCP relay broken after "config vrf bind <Vlan>…
Xichen96 Apr 25, 2026
8b8ebd0
Merge branch 'master' into dev/xichenlin/fix-dhcp4relay-vlan-interfac…
ashutosh-agrawal Apr 28, 2026
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8 changes: 4 additions & 4 deletions dhcp4relay/src/dhcp4relay.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -864,7 +864,7 @@ void update_vlan_mapping(std::string vlan, bool is_add) {
if (is_add) {
std::string value;
std::shared_ptr<swss::Table> vlan_intf_tbl = std::make_shared<swss::Table>(config_db.get(), CFG_VLAN_INTF_TABLE_NAME);
vlan_intf_tbl->hget(vlan, "vrf_name", value);
vlan_intf_tbl->hget(vlan, VRF_NAME_FIELD, value);
if (value.size() <= 0) {
/* use default instance as vrf */
vlan_vrf_map[vlan] = "default";
Expand Down Expand Up @@ -1337,7 +1337,7 @@ void config_event_callback(evutil_socket_t fd, short event, void *arg) {
std::string value;
std::shared_ptr<swss::Table> dhcp_relay_tbl = std::make_shared<swss::Table>(config_db.get(),
"DHCPV4_RELAY");
dhcp_relay_tbl->hget((msg->vlan), "server_vrf", value);
dhcp_relay_tbl->hget((msg->vlan), SERVER_VRF_FIELD, value);
if ((msg->vrf.empty()) || (value.length() != 0)) {
return;
}
Expand Down Expand Up @@ -1381,7 +1381,7 @@ void config_event_callback(evutil_socket_t fd, short event, void *arg) {
std::string value;

// Check for the presence of specific keys
v4_relay_intf_tbl->hget(vlan.second.vlan, "link_selection", value);
v4_relay_intf_tbl->hget(vlan.second.vlan, LINK_SELECTION_FIELD, value);
// Check if "link_selection" is present
if (value.length() > 0) {
// Fetch the value of "link_selection" from the database
Expand All @@ -1391,7 +1391,7 @@ void config_event_callback(evutil_socket_t fd, short event, void *arg) {
vlan.second.link_selection_opt.clear();
}

v4_relay_intf_tbl->hget(vlan.second.vlan, "source_interface", value);
v4_relay_intf_tbl->hget(vlan.second.vlan, SOURCE_INTERFACE_FIELD, value);
// Check if "source_interface" is present
if (value.length() > 0) {
// Fetch the value of "source_interface" from the database
Expand Down
5 changes: 5 additions & 0 deletions dhcp4relay/src/dhcp4relay.h
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Original file line number Diff line number Diff line change
Expand Up @@ -27,6 +27,11 @@
#define DHCPv4_OPTION_LIMIT 255
#define RAWSOCKET_RECV_SIZE 1048576
#define CLIENT_IF_PREFIX "Ethernet"
#define VRF_NAME_FIELD "vrf_name" // typo "vrf" caused VRF-update miss; field is "vrf_name"
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@ashutosh-agrawal ashutosh-agrawal Apr 28, 2026

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The comment can probably be removed. It's already covered in PR description.

#define SERVER_VRF_FIELD "server_vrf"
#define SOURCE_INTERFACE_FIELD "source_interface"
#define LINK_SELECTION_FIELD "link_selection"
#define STATE_FIELD "state"
#define BUFFER_SIZE 9200 // TODO: change to dynamic size based on MTU
#define MAX_DHCP_PKT_SIZE 1472 // 1500 - (IP + UDP)headers
#define MAC_ADDR_STR_LEN 17
Expand Down
14 changes: 7 additions & 7 deletions dhcp4relay/src/dhcp4relay_mgr.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -356,11 +356,11 @@ void DHCPMgr::process_relay_notification(std::deque<swss::KeyOpFieldsValuesTuple
getline(ss, substr, ',');
relay_msg->servers.push_back(substr);
}
} else if (f == "server_vrf") {
} else if (f == SERVER_VRF_FIELD) {
relay_msg->vrf = v;
} else if (f == "source_interface") {
} else if (f == SOURCE_INTERFACE_FIELD) {
relay_msg->source_interface = v;
} else if (f == "link_selection") {
} else if (f == LINK_SELECTION_FIELD) {
relay_msg->link_selection_opt = v;
} else if (f == "server_id_override") {
relay_msg->server_id_override_opt = v;
Expand All @@ -379,7 +379,7 @@ void DHCPMgr::process_relay_notification(std::deque<swss::KeyOpFieldsValuesTuple
std::string value;
std::shared_ptr<swss::DBConnector> config_db = std::make_shared<swss::DBConnector>("CONFIG_DB", 0);
std::shared_ptr<swss::Table> vlan_intf_tbl = std::make_shared<swss::Table>(config_db.get(), CFG_VLAN_INTF_TABLE_NAME);
vlan_intf_tbl->hget(vlan, "vrf_name", value);
vlan_intf_tbl->hget(vlan, VRF_NAME_FIELD, value);
if (value.size() <= 0) {
relay_msg->vrf = "default";
} else {
Expand Down Expand Up @@ -441,7 +441,7 @@ void DHCPMgr::process_feature_notification(std::deque<swss::KeyOpFieldsValuesTup

std::string state;
for (auto &field : kfvFieldsValues(entry)) {
if (fvField(field) == "state") {
if (fvField(field) == STATE_FIELD) {
state = fvValue(field);
break;
}
Expand Down Expand Up @@ -633,7 +633,7 @@ void DHCPMgr::process_vlan_interface_notification(std::deque<swss::KeyOpFieldsVa
vlan = key;
vrf = "default";
for (auto &fv : kfvFieldsValues(entry)) {
if (fvField(fv) == "vrf") {
if (fvField(fv) == VRF_NAME_FIELD) {
vrf = fvValue(fv);
break;
}
Expand Down Expand Up @@ -706,7 +706,7 @@ void DHCPMgr::process_dhcp_server_ipv4_notification(std::deque<swss::KeyOpFields
if (operation == "SET") {
std::string state;
for (auto &fv : kfvFieldsValues(entry)) {
if (fvField(fv) == "state") {
if (fvField(fv) == STATE_FIELD) {
state = fvValue(fv);
break;
}
Expand Down
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