From 2ec527f426348d22796ad30704d206f81a2c3305 Mon Sep 17 00:00:00 2001
From: Maxim Prokhorov <prokhorov.max@outlook.com>
Date: Fri, 27 May 2022 11:11:55 +0300
Subject: [PATCH 01/16] works

---
 cores/esp8266/LwipDhcpServer.cpp              | 24 ++++++++++++++++++-
 cores/esp8266/LwipDhcpServer.h                | 16 +++++++++++++
 .../examples/CustomOffer/CustomOffer.ino      | 16 +++++++++++++
 3 files changed, 55 insertions(+), 1 deletion(-)
 create mode 100644 libraries/ESP8266WiFi/examples/CustomOffer/CustomOffer.ino

diff --git a/cores/esp8266/LwipDhcpServer.cpp b/cores/esp8266/LwipDhcpServer.cpp
index 07270bb6c2..6f31c9062a 100644
--- a/cores/esp8266/LwipDhcpServer.cpp
+++ b/cores/esp8266/LwipDhcpServer.cpp
@@ -534,8 +534,9 @@ void DhcpServer::send_offer(struct dhcps_msg* m)
     u16_t        i;
     create_msg(m);
 
-    end = add_msg_type(&m->options[4], DHCPOFFER);
+    end = add_msg_type(&m->options[4], DHCPOFFER); // 3
     end = add_offer_options(end);
+    end = add_custom_offer_options(end, std::end(m->options) - 1);
     end = add_end(end);
 
     p = pbuf_alloc(PBUF_TRANSPORT, sizeof(struct dhcps_msg), PBUF_RAM);
@@ -658,6 +659,7 @@ void DhcpServer::send_ack(struct dhcps_msg* m)
 
     end = add_msg_type(&m->options[4], DHCPACK);
     end = add_offer_options(end);
+    end = add_custom_offer_options(end, std::end(m->options) - 1);
     end = add_end(end);
 
     p = pbuf_alloc(PBUF_TRANSPORT, sizeof(struct dhcps_msg), PBUF_RAM);
@@ -1591,3 +1593,23 @@ uint32 DhcpServer::dhcps_client_update(u8* bssid, struct ipv4_addr* ip)
 
     return pdhcps_pool->ip.addr;
 }
+
+uint8_t* DhcpServer::add_custom_offer_options(uint8_t* optptr, uint8_t* end) {
+    for (const auto& option : custom_options) {
+        if (option.data.size() > UINT8_MAX) {
+            break;
+        }
+
+        if ((end - optptr) < (2 + (option.data.end() - option.data.begin()))) {
+            break;
+        }
+
+        *optptr++ = option.code;
+        *optptr++ = option.data.size();
+        for (auto it = option.data.begin(); it != option.data.end(); ++it) {
+            *optptr++ = *it;
+        }
+    }
+
+    return optptr;
+}
diff --git a/cores/esp8266/LwipDhcpServer.h b/cores/esp8266/LwipDhcpServer.h
index d5eb6410ef..bc662c91ee 100644
--- a/cores/esp8266/LwipDhcpServer.h
+++ b/cores/esp8266/LwipDhcpServer.h
@@ -33,9 +33,17 @@
 
 #include <lwip/init.h>  // LWIP_VERSION
 
+#include <cstdint>
+#include <vector>
+
 class DhcpServer
 {
 public:
+    struct Option {
+        uint8_t code;
+        std::vector<uint8_t> data;
+    };
+
     DhcpServer(netif* netif);
     ~DhcpServer();
 
@@ -63,6 +71,12 @@ class DhcpServer
 
     void dhcps_set_dns(int num, const ipv4_addr_t* dns);
 
+    template <typename T>
+    void add_custom_offer_option(T&& option) {
+        custom_options.push_back(std::forward<T>(option));
+    }
+
+    void offers();
 protected:
     // legacy C structure and API to eventually turn into C++
 
@@ -76,6 +90,7 @@ class DhcpServer
     void        node_remove_from_list(list_node** phead, list_node* pdelete);
     uint8_t*    add_msg_type(uint8_t* optptr, uint8_t type);
     uint8_t*    add_offer_options(uint8_t* optptr);
+    uint8_t*    add_custom_offer_options(uint8_t* optptr, uint8_t* end);
     uint8_t*    add_end(uint8_t* optptr);
     void        create_msg(struct dhcps_msg* m);
     void        send_offer(struct dhcps_msg* m);
@@ -105,6 +120,7 @@ class DhcpServer
     uint8              offer;
     bool               renew;
 
+    std::vector<Option> custom_options;
     static const uint32 magic_cookie;
 };
 
diff --git a/libraries/ESP8266WiFi/examples/CustomOffer/CustomOffer.ino b/libraries/ESP8266WiFi/examples/CustomOffer/CustomOffer.ino
new file mode 100644
index 0000000000..cfa954ff8e
--- /dev/null
+++ b/libraries/ESP8266WiFi/examples/CustomOffer/CustomOffer.ino
@@ -0,0 +1,16 @@
+#include <Arduino.h>
+#include <ESP8266WiFi.h>
+#include <LwipDhcpServer.h>
+
+void setup() {
+    dhcpSoftAP.add_custom_offer_option(
+        DhcpServer::Option{
+            .code = 43,
+            .data = {0xca,0xfe,0xfe,0xfe,0xfe}
+        });
+    WiFi.softAP("TEST", "testtesttest");
+}
+
+void loop() {
+    delay(100);
+}

From 6ccb6856370c30f77a9d65600973f33ee617e9c1 Mon Sep 17 00:00:00 2001
From: Maxim Prokhorov <prokhorov.max@outlook.com>
Date: Fri, 27 May 2022 11:18:25 +0300
Subject: [PATCH 02/16] fixup! works

---
 cores/esp8266/LwipDhcpServer.cpp | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/cores/esp8266/LwipDhcpServer.cpp b/cores/esp8266/LwipDhcpServer.cpp
index 6f31c9062a..f5f5ebb08b 100644
--- a/cores/esp8266/LwipDhcpServer.cpp
+++ b/cores/esp8266/LwipDhcpServer.cpp
@@ -1596,7 +1596,7 @@ uint32 DhcpServer::dhcps_client_update(u8* bssid, struct ipv4_addr* ip)
 
 uint8_t* DhcpServer::add_custom_offer_options(uint8_t* optptr, uint8_t* end) {
     for (const auto& option : custom_options) {
-        if (option.data.size() > UINT8_MAX) {
+        if (option.data.size() > (UINT8_MAX - 1)) {
             break;
         }
 

From 30b188e66bf6d6744219bbcadec274c2286baa42 Mon Sep 17 00:00:00 2001
From: Maxim Prokhorov <prokhorov.max@outlook.com>
Date: Tue, 31 May 2022 15:02:52 +0300
Subject: [PATCH 03/16] back to callbacks

---
 cores/esp8266/LwipDhcpServer.cpp              | 429 +++++-------------
 cores/esp8266/LwipDhcpServer.h                | 204 +++++++--
 .../examples/CustomOffer/CustomOffer.ino      |  13 +-
 libraries/ESP8266WiFi/src/ESP8266WiFiAP.cpp   |  15 +-
 tests/restyle.sh                              |  14 +-
 tools/sdk/lwip2/include/lwip/arch.h           |   2 +-
 6 files changed, 283 insertions(+), 394 deletions(-)

diff --git a/cores/esp8266/LwipDhcpServer.cpp b/cores/esp8266/LwipDhcpServer.cpp
index f5f5ebb08b..da36f0f368 100644
--- a/cores/esp8266/LwipDhcpServer.cpp
+++ b/cores/esp8266/LwipDhcpServer.cpp
@@ -36,8 +36,6 @@
 
 #include <lwip/init.h>  // LWIP_VERSION
 
-#define DHCPS_LEASE_TIME_DEF (120)
-
 #define USE_DNS
 
 #include "lwip/inet.h"
@@ -52,6 +50,8 @@
 #include "user_interface.h"
 #include "mem.h"
 
+#include <cstring>
+
 typedef struct dhcps_state
 {
     sint16_t state;
@@ -80,12 +80,6 @@ struct dhcps_lease
     struct ipv4_addr end_ip;
 };
 
-enum dhcps_offer_option
-{
-    OFFER_START  = 0x00,
-    OFFER_ROUTER = 0x01,
-    OFFER_END
-};
 #endif
 
 typedef enum
@@ -109,7 +103,6 @@ struct dhcps_pool
     dhcps_state_t    state;
 };
 
-#define DHCPS_LEASE_TIMER dhcps_lease_time  // 0x05A0
 #define DHCPS_MAX_LEASE 0x64
 #define BOOTP_BROADCAST 0x8000
 
@@ -122,13 +115,13 @@ struct dhcps_pool
 #define DHCPS_SERVER_PORT 67
 #define DHCPS_CLIENT_PORT 68
 
-#define DHCPDISCOVER 1
-#define DHCPOFFER 2
-#define DHCPREQUEST 3
-#define DHCPDECLINE 4
-#define DHCPACK 5
-#define DHCPNAK 6
-#define DHCPRELEASE 7
+static constexpr uint8_t DHCPDISCOVER = 1;
+static constexpr uint8_t DHCPOFFER    = 2;
+static constexpr uint8_t DHCPREQUEST  = 3;
+static constexpr uint8_t DHCPDECLINE  = 4;
+static constexpr uint8_t DHCPACK      = 5;
+static constexpr uint8_t DHCPNAK      = 6;
+static constexpr uint8_t DHCPRELEASE  = 7;
 
 #define DHCP_OPTION_SUBNET_MASK 1
 #define DHCP_OPTION_ROUTER 3
@@ -154,8 +147,6 @@ struct dhcps_pool
 #define DHCPS_STATE_IDLE 5
 #define DHCPS_STATE_RELEASE 6
 
-#define dhcps_router_enabled(offer) ((offer & OFFER_ROUTER) != 0)
-
 #ifdef MEMLEAK_DEBUG
 const char mem_debug_file[] ICACHE_RODATA_ATTR = __FILE__;
 #endif
@@ -183,13 +174,6 @@ int fw_has_started_softap_dhcps = 0;
 
 DhcpServer::DhcpServer(netif* netif) : _netif(netif)
 {
-    pcb_dhcps        = nullptr;
-    dns_address.addr = 0;
-    plist            = nullptr;
-    offer            = 0xFF;
-    renew            = false;
-    dhcps_lease_time = DHCPS_LEASE_TIME_DEF;  // minute
-
     if (netif->num == SOFTAP_IF && fw_has_started_softap_dhcps == 1)
     {
         // When nonos-sdk starts DHCPS at boot:
@@ -209,15 +193,6 @@ DhcpServer::DhcpServer(netif* netif) : _netif(netif)
 // wifi_softap_set_station_info is missing in user_interface.h:
 extern "C" void wifi_softap_set_station_info(uint8_t* mac, struct ipv4_addr*);
 
-void DhcpServer::dhcps_set_dns(int num, const ipv4_addr_t* dns)
-{
-    (void)num;
-    if (!ip4_addr_isany(dns))
-    {
-        ip4_addr_copy(dns_address, *dns);
-    }
-}
-
 /******************************************************************************
     FunctionName : node_insert_to_list
     Description  : insert the node to the list
@@ -315,8 +290,8 @@ bool DhcpServer::add_dhcps_lease(uint8* macaddr)
     struct dhcps_pool* pdhcps_pool = nullptr;
     list_node*         pback_node  = nullptr;
 
-    uint32 start_ip = dhcps_lease.start_ip.addr;
-    uint32 end_ip   = dhcps_lease.end_ip.addr;
+    uint32 start_ip = lease.start_ip.addr;
+    uint32 end_ip   = lease.end_ip.addr;
 
     for (pback_node = plist; pback_node != nullptr; pback_node = pback_node->pnext)
     {
@@ -345,7 +320,7 @@ bool DhcpServer::add_dhcps_lease(uint8* macaddr)
     pdhcps_pool          = (struct dhcps_pool*)zalloc(sizeof(struct dhcps_pool));
     pdhcps_pool->ip.addr = start_ip;
     memcpy(pdhcps_pool->mac, macaddr, sizeof(pdhcps_pool->mac));
-    pdhcps_pool->lease_timer = DHCPS_LEASE_TIMER;
+    pdhcps_pool->lease_timer = this->lease_time;
     pdhcps_pool->type        = DHCPS_TYPE_STATIC;
     pdhcps_pool->state       = DHCPS_STATE_ONLINE;
     pback_node               = (list_node*)zalloc(sizeof(list_node));
@@ -358,145 +333,48 @@ bool DhcpServer::add_dhcps_lease(uint8* macaddr)
 
 ///////////////////////////////////////////////////////////////////////////////////
 /*
-    DHCP msg
-
-    @param optptr -- DHCP msg
-    @param type -- option
+    Set DHCP msg offer options for the given server
 
-    @return uint8_t* DHCP msg
+    @param buffer -- DHCP options buffer
+    @param server -- DHCP server instance
 */
 ///////////////////////////////////////////////////////////////////////////////////
-uint8_t* DhcpServer::add_msg_type(uint8_t* optptr, uint8_t type)
+void DhcpServer::add_offer_options(OptionsBuffer& buffer)
 {
-    *optptr++ = DHCP_OPTION_MSG_TYPE;
-    *optptr++ = 1;
-    *optptr++ = type;
-    return optptr;
-}
-///////////////////////////////////////////////////////////////////////////////////
-/*
-    DHCP msg offer
+    buffer.add(DHCP_OPTION_SUBNET_MASK, ip_2_ip4(&_netif->netmask));
+    buffer.add(DHCP_OPTION_LEASE_TIME, lease_time);
+    buffer.add(DHCP_OPTION_SERVER_ID, ip_2_ip4(&_netif->ip_addr));
 
-    @param optptr -- DHCP msg
-
-    @return uint8_t* DHCP msg
-*/
-///////////////////////////////////////////////////////////////////////////////////
-uint8_t* DhcpServer::add_offer_options(uint8_t* optptr)
-{
-    // struct ipv4_addr ipadd;
-    // ipadd.addr = server_address.addr;
-#define ipadd (_netif->ip_addr)
-
-    // struct ip_info if_ip;
-    // bzero(&if_ip, sizeof(struct ip_info));
-    // wifi_get_ip_info(SOFTAP_IF, &if_ip);
-#define if_ip (*_netif)
-
-    *optptr++ = DHCP_OPTION_SUBNET_MASK;
-    *optptr++ = 4;
-    *optptr++ = ip4_addr1(ip_2_ip4(&if_ip.netmask));
-    *optptr++ = ip4_addr2(ip_2_ip4(&if_ip.netmask));
-    *optptr++ = ip4_addr3(ip_2_ip4(&if_ip.netmask));
-    *optptr++ = ip4_addr4(ip_2_ip4(&if_ip.netmask));
-
-    *optptr++ = DHCP_OPTION_LEASE_TIME;
-    *optptr++ = 4;
-    *optptr++ = ((DHCPS_LEASE_TIMER * 60) >> 24) & 0xFF;
-    *optptr++ = ((DHCPS_LEASE_TIMER * 60) >> 16) & 0xFF;
-    *optptr++ = ((DHCPS_LEASE_TIMER * 60) >> 8) & 0xFF;
-    *optptr++ = ((DHCPS_LEASE_TIMER * 60) >> 0) & 0xFF;
-
-    *optptr++ = DHCP_OPTION_SERVER_ID;
-    *optptr++ = 4;
-    *optptr++ = ip4_addr1(ip_2_ip4(&ipadd));
-    *optptr++ = ip4_addr2(ip_2_ip4(&ipadd));
-    *optptr++ = ip4_addr3(ip_2_ip4(&ipadd));
-    *optptr++ = ip4_addr4(ip_2_ip4(&ipadd));
-
-    if (dhcps_router_enabled(offer) && ip_2_ip4(&if_ip.gw)->addr)
+    if (offer_router && !ip4_addr_isany_val(*ip_2_ip4(&_netif->gw)))
     {
-        *optptr++ = DHCP_OPTION_ROUTER;
-        *optptr++ = 4;
-        *optptr++ = ip4_addr1(ip_2_ip4(&if_ip.gw));
-        *optptr++ = ip4_addr2(ip_2_ip4(&if_ip.gw));
-        *optptr++ = ip4_addr3(ip_2_ip4(&if_ip.gw));
-        *optptr++ = ip4_addr4(ip_2_ip4(&if_ip.gw));
+        buffer.add(DHCP_OPTION_ROUTER, ip_2_ip4(&_netif->gw));
     }
 
 #ifdef USE_DNS
-    *optptr++ = DHCP_OPTION_DNS_SERVER;
-    *optptr++ = 4;
-    if (dns_address.addr == 0)
-    {
-        *optptr++ = ip4_addr1(ip_2_ip4(&ipadd));
-        *optptr++ = ip4_addr2(ip_2_ip4(&ipadd));
-        *optptr++ = ip4_addr3(ip_2_ip4(&ipadd));
-        *optptr++ = ip4_addr4(ip_2_ip4(&ipadd));
-    }
-    else
-    {
-        *optptr++ = ip4_addr1(&dns_address);
-        *optptr++ = ip4_addr2(&dns_address);
-        *optptr++ = ip4_addr3(&dns_address);
-        *optptr++ = ip4_addr4(&dns_address);
-    }
+    buffer.add(DHCP_OPTION_DNS_SERVER, !ip4_addr_isany_val(*ip_2_ip4(&dns_address))
+                                           ? ip_2_ip4(&dns_address)
+                                           : ip_2_ip4(&_netif->ip_addr));
 #endif
 
-    *optptr++ = DHCP_OPTION_BROADCAST_ADDRESS;
-    *optptr++ = 4;
-    // XXXFIXME do better than that, we have netmask
-    *optptr++ = ip4_addr1(ip_2_ip4(&ipadd));
-    *optptr++ = ip4_addr2(ip_2_ip4(&ipadd));
-    *optptr++ = ip4_addr3(ip_2_ip4(&ipadd));
-    *optptr++ = 255;
-
-    *optptr++ = DHCP_OPTION_INTERFACE_MTU;
-    *optptr++ = 2;
-    *optptr++ = 0x05;
-    *optptr++ = 0xdc;  // 1500
-
-    *optptr++ = DHCP_OPTION_PERFORM_ROUTER_DISCOVERY;
-    *optptr++ = 1;
-    *optptr++ = 0x00;
-
-#if 0  // vendor specific uninitialized (??)
-    *optptr++ = 43; // vendor specific
-    *optptr++ = 6;
-    // uninitialized ?
-#endif
+    {
+        const auto* addr = ip_2_ip4(&_netif->ip_addr);
+        const auto  broadcast
+            = ip4_addr_t { .addr = (addr->addr & ip_2_ip4(&_netif->netmask)->addr) | ~addr->addr };
 
-#if 0  // already set (DHCP_OPTION_SUBNET_MASK==1) (??)
-    *optptr++ = 0x01;
-    *optptr++ = 4;
-    *optptr++ = 0;
-    *optptr++ = 0;
-    *optptr++ = 0;
-    *optptr++ = 2;
-#endif
+        buffer.add(DHCP_OPTION_BROADCAST_ADDRESS, &broadcast);
+    }
 
-    return optptr;
+    // TODO: _netif->mtu ?
+    static constexpr uint16_t Mtu { 1500 };
+    buffer.add(DHCP_OPTION_INTERFACE_MTU, Mtu);
 
-#undef ipadd
-#undef if_ip
+    static constexpr uint8_t RouterDiscovery { 0 };
+    buffer.add(DHCP_OPTION_PERFORM_ROUTER_DISCOVERY, RouterDiscovery);
 }
-///////////////////////////////////////////////////////////////////////////////////
-/*
-    DHCP msg
-
-    @param optptr -- DHCP msg
 
-    @return uint8_t* DHCP msg
-*/
-///////////////////////////////////////////////////////////////////////////////////
-uint8_t* DhcpServer::add_end(uint8_t* optptr)
-{
-    *optptr++ = DHCP_OPTION_END;
-    return optptr;
-}
 ///////////////////////////////////////////////////////////////////////////////////
 ///////////////////////////////////////////////////////////////////////////////////
-void DhcpServer::create_msg(struct dhcps_msg* m)
+DhcpServer::OptionsBuffer DhcpServer::create_msg(struct dhcps_msg* m)
 {
     struct ipv4_addr client;
 
@@ -517,6 +395,8 @@ void DhcpServer::create_msg(struct dhcps_msg* m)
     memset((char*)m->file, 0, sizeof(m->file));
     memset((char*)m->options, 0, sizeof(m->options));
     memcpy((char*)m->options, &magic_cookie, sizeof(magic_cookie));
+
+    return { &m->options[sizeof(magic_cookie)], std::end(m->options) };
 }
 ///////////////////////////////////////////////////////////////////////////////////
 /*
@@ -527,17 +407,18 @@ void DhcpServer::create_msg(struct dhcps_msg* m)
 ///////////////////////////////////////////////////////////////////////////////////
 void DhcpServer::send_offer(struct dhcps_msg* m)
 {
-    uint8_t*     end;
     struct pbuf *p, *q;
-    u8_t*        data;
-    u16_t        cnt = 0;
-    u16_t        i;
-    create_msg(m);
 
-    end = add_msg_type(&m->options[4], DHCPOFFER); // 3
-    end = add_offer_options(end);
-    end = add_custom_offer_options(end, std::end(m->options) - 1);
-    end = add_end(end);
+    auto options = create_msg(m);
+    options.add(DHCP_OPTION_MSG_TYPE, DHCPOFFER);
+
+    add_offer_options(options);
+    if (custom_offer_options)
+    {
+        custom_offer_options(*this, options);
+    }
+
+    options.add(DHCP_OPTION_END);
 
     p = pbuf_alloc(PBUF_TRANSPORT, sizeof(struct dhcps_msg), PBUF_RAM);
 #if DHCPS_DEBUG
@@ -553,12 +434,7 @@ void DhcpServer::send_offer(struct dhcps_msg* m)
         q = p;
         while (q != nullptr)
         {
-            data = (u8_t*)q->payload;
-            for (i = 0; i < q->len; i++)
-            {
-                data[i] = ((u8_t*)m)[cnt++];
-            }
-
+            std::memcpy((u8_t*)q->payload, reinterpret_cast<u8_t*>(&m), q->len);
             q = q->next;
         }
     }
@@ -592,15 +468,11 @@ void DhcpServer::send_offer(struct dhcps_msg* m)
 ///////////////////////////////////////////////////////////////////////////////////
 void DhcpServer::send_nak(struct dhcps_msg* m)
 {
-    u8_t*        end;
     struct pbuf *p, *q;
-    u8_t*        data;
-    u16_t        cnt = 0;
-    u16_t        i;
-    create_msg(m);
 
-    end = add_msg_type(&m->options[4], DHCPNAK);
-    end = add_end(end);
+    auto options = create_msg(m);
+    options.add(DHCP_OPTION_MSG_TYPE, DHCPNAK);
+    options.add(DHCP_OPTION_END);
 
     p = pbuf_alloc(PBUF_TRANSPORT, sizeof(struct dhcps_msg), PBUF_RAM);
 #if DHCPS_DEBUG
@@ -616,12 +488,7 @@ void DhcpServer::send_nak(struct dhcps_msg* m)
         q = p;
         while (q != nullptr)
         {
-            data = (u8_t*)q->payload;
-            for (i = 0; i < q->len; i++)
-            {
-                data[i] = ((u8_t*)m)[cnt++];
-            }
-
+            std::memcpy((u8_t*)q->payload, (u8_t*)m, q->len);
             q = q->next;
         }
     }
@@ -650,17 +517,18 @@ void DhcpServer::send_nak(struct dhcps_msg* m)
 ///////////////////////////////////////////////////////////////////////////////////
 void DhcpServer::send_ack(struct dhcps_msg* m)
 {
-    u8_t*        end;
     struct pbuf *p, *q;
-    u8_t*        data;
-    u16_t        cnt = 0;
-    u16_t        i;
-    create_msg(m);
 
-    end = add_msg_type(&m->options[4], DHCPACK);
-    end = add_offer_options(end);
-    end = add_custom_offer_options(end, std::end(m->options) - 1);
-    end = add_end(end);
+    auto options = create_msg(m);
+    options.add(DHCP_OPTION_MSG_TYPE, DHCPACK);
+
+    add_offer_options(options);
+    if (custom_offer_options)
+    {
+        custom_offer_options(*this, options);
+    }
+
+    options.add(DHCP_OPTION_END);
 
     p = pbuf_alloc(PBUF_TRANSPORT, sizeof(struct dhcps_msg), PBUF_RAM);
 #if DHCPS_DEBUG
@@ -676,12 +544,7 @@ void DhcpServer::send_ack(struct dhcps_msg* m)
         q = p;
         while (q != nullptr)
         {
-            data = (u8_t*)q->payload;
-            for (i = 0; i < q->len; i++)
-            {
-                data[i] = ((u8_t*)m)[cnt++];
-            }
-
+            std::memcpy((u8_t*)q->payload, (u8_t*)m, q->len);
             q = q->next;
         }
     }
@@ -962,15 +825,15 @@ void DhcpServer::init_dhcps_lease(uint32 ip)
     uint32 softap_ip = 0, local_ip = 0;
     uint32 start_ip = 0;
     uint32 end_ip   = 0;
-    if (dhcps_lease.enable == true)
+    if (lease.enable == true)
     {
         softap_ip = htonl(ip);
-        start_ip  = htonl(dhcps_lease.start_ip.addr);
-        end_ip    = htonl(dhcps_lease.end_ip.addr);
+        start_ip  = htonl(lease.start_ip.addr);
+        end_ip    = htonl(lease.end_ip.addr);
         /*config ip information can't contain local ip*/
         if ((start_ip <= softap_ip) && (softap_ip <= end_ip))
         {
-            dhcps_lease.enable = false;
+            lease.enable = false;
         }
         else
         {
@@ -979,12 +842,12 @@ void DhcpServer::init_dhcps_lease(uint32 ip)
             if (((start_ip >> 8 != softap_ip) || (end_ip >> 8 != softap_ip))
                 || (end_ip - start_ip > DHCPS_MAX_LEASE))
             {
-                dhcps_lease.enable = false;
+                lease.enable = false;
             }
         }
     }
 
-    if (dhcps_lease.enable == false)
+    if (lease.enable == false)
     {
         local_ip = softap_ip = htonl(ip);
         softap_ip &= 0xFFFFFF00;
@@ -998,15 +861,15 @@ void DhcpServer::init_dhcps_lease(uint32 ip)
             local_ip++;
         }
 
-        bzero(&dhcps_lease, sizeof(dhcps_lease));
-        dhcps_lease.start_ip.addr = softap_ip | local_ip;
-        dhcps_lease.end_ip.addr   = softap_ip | (local_ip + DHCPS_MAX_LEASE - 1);
-        dhcps_lease.start_ip.addr = htonl(dhcps_lease.start_ip.addr);
-        dhcps_lease.end_ip.addr   = htonl(dhcps_lease.end_ip.addr);
+        bzero(&lease, sizeof(lease));
+        lease.start_ip.addr = softap_ip | local_ip;
+        lease.end_ip.addr   = softap_ip | (local_ip + DHCPS_MAX_LEASE - 1);
+        lease.start_ip.addr = htonl(lease.start_ip.addr);
+        lease.end_ip.addr   = htonl(lease.end_ip.addr);
     }
-    //  dhcps_lease.start_ip.addr = htonl(dhcps_lease.start_ip.addr);
-    //  dhcps_lease.end_ip.addr= htonl(dhcps_lease.end_ip.addr);
-    //  os_printf("start_ip = 0x%x, end_ip = 0x%x\n",dhcps_lease.start_ip, dhcps_lease.end_ip);
+    //  lease.start_ip.addr = htonl(lease.start_ip.addr);
+    //  lease.end_ip.addr= htonl(lease.end_ip.addr);
+    //  os_printf("start_ip = 0x%x, end_ip = 0x%x\n",lease.start_ip, lease.end_ip);
 }
 ///////////////////////////////////////////////////////////////////////////////////
 
@@ -1151,13 +1014,13 @@ bool DhcpServer::set_dhcps_lease(struct dhcps_lease* please)
             return false;
         }
 
-        bzero(&dhcps_lease, sizeof(dhcps_lease));
-        //      dhcps_lease.start_ip.addr = start_ip;
-        //      dhcps_lease.end_ip.addr = end_ip;
-        dhcps_lease.start_ip.addr = please->start_ip.addr;
-        dhcps_lease.end_ip.addr   = please->end_ip.addr;
+        bzero(&lease, sizeof(lease));
+        //      lease.start_ip.addr = start_ip;
+        //      lease.end_ip.addr = end_ip;
+        lease.start_ip.addr = please->start_ip.addr;
+        lease.end_ip.addr   = please->end_ip.addr;
     }
-    dhcps_lease.enable = please->enable;
+    lease.enable = please->enable;
     //  dhcps_lease_flag = false;
     return true;
 }
@@ -1186,7 +1049,7 @@ bool DhcpServer::get_dhcps_lease(struct dhcps_lease* please)
     }
 
     //  if (dhcps_lease_flag){
-    if (dhcps_lease.enable == false)
+    if (lease.enable == false)
     {
         if (isRunning())
         {
@@ -1195,20 +1058,20 @@ bool DhcpServer::get_dhcps_lease(struct dhcps_lease* please)
     }
     else
     {
-        //      bzero(please, sizeof(dhcps_lease));
+        //      bzero(please, sizeof(*please));
         //      if (!isRunning()){
-        //          please->start_ip.addr = htonl(dhcps_lease.start_ip.addr);
-        //          please->end_ip.addr = htonl(dhcps_lease.end_ip.addr);
+        //          please->start_ip.addr = htonl(lease.start_ip.addr);
+        //          please->end_ip.addr = htonl(lease.end_ip.addr);
         //      }
     }
 
     //  if (isRunning()){
-    //      bzero(please, sizeof(dhcps_lease));
-    //      please->start_ip.addr = dhcps_lease.start_ip.addr;
-    //      please->end_ip.addr = dhcps_lease.end_ip.addr;
+    //      bzero(please, sizeof(*please));
+    //      please->start_ip.addr = lease.start_ip.addr;
+    //      please->end_ip.addr = lease.end_ip.addr;
     //  }
-    please->start_ip.addr = dhcps_lease.start_ip.addr;
-    please->end_ip.addr   = dhcps_lease.end_ip.addr;
+    please->start_ip.addr = lease.start_ip.addr;
+    please->end_ip.addr   = lease.end_ip.addr;
     return true;
 }
 
@@ -1278,79 +1141,9 @@ void DhcpServer::dhcps_coarse_tmr(void)
     }
 }
 
-bool DhcpServer::set_dhcps_offer_option(uint8 level, void* optarg)
-{
-    bool offer_flag = true;
-    // uint8 option = 0;
-    if (optarg == nullptr && !isRunning())
-    {
-        return false;
-    }
-
-    if (level <= OFFER_START || level >= OFFER_END)
-    {
-        return false;
-    }
-
-    switch (level)
-    {
-    case OFFER_ROUTER:
-        offer      = (*(uint8*)optarg) & 0x01;
-        offer_flag = true;
-        break;
-    default:
-        offer_flag = false;
-        break;
-    }
-    return offer_flag;
-}
-
-bool DhcpServer::set_dhcps_lease_time(uint32 minute)
-{
-    if (_netif->num == SOFTAP_IF)
-    {
-        uint8 opmode = wifi_get_opmode();
-        if (opmode == STATION_MODE || opmode == NULL_MODE)
-        {
-            return false;
-        }
-    }
-
-    if (isRunning())
-    {
-        return false;
-    }
-
-    if (minute == 0)
-    {
-        return false;
-    }
-    dhcps_lease_time = minute;
-    return true;
-}
-
-bool DhcpServer::reset_dhcps_lease_time(void)
+void DhcpServer::resetLeaseTime()
 {
-    if (_netif->num == SOFTAP_IF)
-    {
-        uint8 opmode = wifi_get_opmode();
-        if (opmode == STATION_MODE || opmode == NULL_MODE)
-        {
-            return false;
-        }
-    }
-
-    if (isRunning())
-    {
-        return false;
-    }
-    dhcps_lease_time = DHCPS_LEASE_TIME_DEF;
-    return true;
-}
-
-uint32 DhcpServer::get_dhcps_lease_time(void)  // minute
-{
-    return dhcps_lease_time;
+    lease_time = DefaultLeaseTime;
 }
 
 void DhcpServer::dhcps_client_leave(u8* bssid, struct ipv4_addr* ip, bool force)
@@ -1409,8 +1202,8 @@ uint32 DhcpServer::dhcps_client_update(u8* bssid, struct ipv4_addr* ip)
     list_node*         pmac_node   = nullptr;
     list_node*         pip_node    = nullptr;
     bool               flag        = false;
-    uint32             start_ip    = dhcps_lease.start_ip.addr;
-    uint32             end_ip      = dhcps_lease.end_ip.addr;
+    uint32             start_ip    = lease.start_ip.addr;
+    uint32             end_ip      = lease.end_ip.addr;
     dhcps_type_t       type        = DHCPS_TYPE_DYNAMIC;
     if (bssid == nullptr)
     {
@@ -1518,7 +1311,7 @@ uint32 DhcpServer::dhcps_client_update(u8* bssid, struct ipv4_addr* ip)
                 type  = DHCPS_TYPE_DYNAMIC;
             }
 
-            pdhcps_pool->lease_timer = DHCPS_LEASE_TIMER;
+            pdhcps_pool->lease_timer = this->lease_time;
             pdhcps_pool->type        = type;
             pdhcps_pool->state       = DHCPS_STATE_ONLINE;
         }
@@ -1539,7 +1332,7 @@ uint32 DhcpServer::dhcps_client_update(u8* bssid, struct ipv4_addr* ip)
             }
 
             node_remove_from_list(&plist, pmac_node);
-            pdhcps_pool->lease_timer = DHCPS_LEASE_TIMER;
+            pdhcps_pool->lease_timer = this->lease_time;
             pdhcps_pool->type        = type;
             pdhcps_pool->state       = DHCPS_STATE_ONLINE;
             node_insert_to_list(&plist, pmac_node);
@@ -1555,7 +1348,7 @@ uint32 DhcpServer::dhcps_client_update(u8* bssid, struct ipv4_addr* ip)
                 return IPADDR_ANY;
             }
             memcpy(pdhcps_pool->mac, bssid, sizeof(pdhcps_pool->mac));
-            pdhcps_pool->lease_timer = DHCPS_LEASE_TIMER;
+            pdhcps_pool->lease_timer = this->lease_time;
             pdhcps_pool->type        = type;
             pdhcps_pool->state       = DHCPS_STATE_ONLINE;
         }
@@ -1581,7 +1374,7 @@ uint32 DhcpServer::dhcps_client_update(u8* bssid, struct ipv4_addr* ip)
                 return IPADDR_ANY;
             }
             memcpy(pdhcps_pool->mac, bssid, sizeof(pdhcps_pool->mac));
-            pdhcps_pool->lease_timer = DHCPS_LEASE_TIMER;
+            pdhcps_pool->lease_timer = this->lease_time;
             pdhcps_pool->type        = type;
             pdhcps_pool->state       = DHCPS_STATE_ONLINE;
             pback_node               = (list_node*)zalloc(sizeof(list_node));
@@ -1593,23 +1386,3 @@ uint32 DhcpServer::dhcps_client_update(u8* bssid, struct ipv4_addr* ip)
 
     return pdhcps_pool->ip.addr;
 }
-
-uint8_t* DhcpServer::add_custom_offer_options(uint8_t* optptr, uint8_t* end) {
-    for (const auto& option : custom_options) {
-        if (option.data.size() > (UINT8_MAX - 1)) {
-            break;
-        }
-
-        if ((end - optptr) < (2 + (option.data.end() - option.data.begin()))) {
-            break;
-        }
-
-        *optptr++ = option.code;
-        *optptr++ = option.data.size();
-        for (auto it = option.data.begin(); it != option.data.end(); ++it) {
-            *optptr++ = *it;
-        }
-    }
-
-    return optptr;
-}
diff --git a/cores/esp8266/LwipDhcpServer.h b/cores/esp8266/LwipDhcpServer.h
index bc662c91ee..de1704707f 100644
--- a/cores/esp8266/LwipDhcpServer.h
+++ b/cores/esp8266/LwipDhcpServer.h
@@ -31,28 +31,161 @@
 #ifndef __DHCPS_H__
 #define __DHCPS_H__
 
-#include <lwip/init.h>  // LWIP_VERSION
+#include <lwip/init.h>
 
 #include <cstdint>
-#include <vector>
+#include <cstddef>
+#include <cstring>
+
+#include <sys/pgmspace.h>
+
+#include <array>
+#include <initializer_list>
 
 class DhcpServer
 {
 public:
-    struct Option {
-        uint8_t code;
-        std::vector<uint8_t> data;
+    struct OptionsBuffer
+    {
+        OptionsBuffer(uint8_t* begin, uint8_t* end) : _it(begin), _begin(begin), _end(end) { }
+
+        OptionsBuffer& add(uint8_t code, const uint8_t* data, size_t size)
+        {
+            if (size >= UINT8_MAX)
+            {
+                return *this;
+            }
+
+            if ((size_t)(_end - _it) < (size + 2))
+            {
+                return *this;
+            }
+
+            *_it++ = code;
+            *_it++ = size;
+
+            memcpy_P(_it, data, size);
+            _it += size;
+
+            return *this;
+        }
+
+        OptionsBuffer& add(uint8_t code, const char* data, size_t size)
+        {
+            return add(code, reinterpret_cast<const uint8_t*>(data), size);
+        }
+
+        template<size_t Size>
+        OptionsBuffer& add(uint8_t code, const char (&data)[Size])
+        {
+            return add(code, &data[0], Size - 1);
+        }
+
+        template<size_t Size>
+        OptionsBuffer& add(uint8_t code, const uint8_t (&data)[Size])
+        {
+            return add(code, &data[0], Size);
+        }
+
+        OptionsBuffer& add(uint8_t code, std::initializer_list<uint8_t> data)
+        {
+            return add(code, data.begin(), data.size());
+        }
+
+        OptionsBuffer& add(uint8_t code, const ip4_addr_t* addr)
+        {
+            return add(code,
+                       { ip4_addr1(addr), ip4_addr2(addr), ip4_addr3(addr), ip4_addr4(addr) });
+        }
+
+        OptionsBuffer& add(uint8_t code, uint8_t value)
+        {
+            uint8_t buffer[] { value };
+            return add(code, buffer, sizeof(buffer));
+        }
+
+        OptionsBuffer& add(uint8_t code, uint16_t value)
+        {
+            uint8_t buffer[2] { static_cast<uint8_t>((value >> 8) & 0xff),
+                                static_cast<uint8_t>(value & 0xff) };
+            return add(code, buffer, sizeof(buffer));
+        }
+
+        OptionsBuffer& add(uint8_t code, uint32_t value)
+        {
+            uint8_t buffer[4] { static_cast<uint8_t>((value >> 24) & 0xff),
+                                static_cast<uint8_t>((value >> 16) & 0xff),
+                                static_cast<uint8_t>((value >> 8) & 0xff),
+                                static_cast<uint8_t>((value & 0xff)) };
+            return add(code, buffer, sizeof(buffer));
+        }
+
+        OptionsBuffer& add(uint8_t code)
+        {
+            if (_it != _end)
+            {
+                *_it++ = code;
+            }
+            return *this;
+        }
+
+    private:
+        uint8_t* _it;
+        uint8_t* _begin;
+        uint8_t* _end;
     };
 
+    using OfferOptionsCallback = void (*)(const DhcpServer&, OptionsBuffer&);
+
     DhcpServer(netif* netif);
     ~DhcpServer();
 
-    void setDns(int num, const ipv4_addr_t* dns);
+    netif* getNetif() const
+    {
+        return _netif;
+    }
+
+    void setRouter(bool value)
+    {
+        offer_router = value;
+    }
+
+    bool getRouter() const
+    {
+        return offer_router;
+    }
+
+    void setDns(ip_addr_t addr)
+    {
+        dns_address = addr;
+    }
+
+    ip_addr_t getDns() const
+    {
+        return dns_address;
+    }
+
+    void resetLeaseTime();
+
+    void setLeaseTime(uint32_t minutes)
+    {
+        lease_time = minutes;
+    }
+
+    uint32_t getLeaseTime() const
+    {
+        return lease_time;
+    }
 
     bool begin(ip_info* info);
     void end();
     bool isRunning();
 
+    // Will call this on ACK and OFFER replies
+    // `options.add(...)` to append to the options list
+    // (does not check for duplicates!)
+    OfferOptionsCallback custom_offer_options = nullptr;
+
     // this is the C interface encapsulated in a class
     // (originally dhcpserver.c in lwIP-v1.4 in NonOS-SDK)
     // (not changing everything at once)
@@ -60,24 +193,16 @@ class DhcpServer
 
     // legacy public C structure and API to eventually turn into C++
 
-    void   init_dhcps_lease(uint32 ip);
-    bool   set_dhcps_lease(struct dhcps_lease* please);
-    bool   get_dhcps_lease(struct dhcps_lease* please);
-    bool   set_dhcps_offer_option(uint8 level, void* optarg);
-    bool   set_dhcps_lease_time(uint32 minute);
-    bool   reset_dhcps_lease_time(void);
-    uint32 get_dhcps_lease_time(void);
-    bool   add_dhcps_lease(uint8* macaddr);
-
-    void dhcps_set_dns(int num, const ipv4_addr_t* dns);
-
-    template <typename T>
-    void add_custom_offer_option(T&& option) {
-        custom_options.push_back(std::forward<T>(option));
-    }
+    void init_dhcps_lease(uint32 ip);
+    bool set_dhcps_lease(struct dhcps_lease* please);
+    bool get_dhcps_lease(struct dhcps_lease* please);
+    bool add_dhcps_lease(uint8* macaddr);
 
     void offers();
+
 protected:
+    void add_offer_options(OptionsBuffer&);
+
     // legacy C structure and API to eventually turn into C++
 
     typedef struct _list_node
@@ -86,13 +211,11 @@ class DhcpServer
         struct _list_node* pnext;
     } list_node;
 
-    void        node_insert_to_list(list_node** phead, list_node* pinsert);
-    void        node_remove_from_list(list_node** phead, list_node* pdelete);
-    uint8_t*    add_msg_type(uint8_t* optptr, uint8_t type);
-    uint8_t*    add_offer_options(uint8_t* optptr);
-    uint8_t*    add_custom_offer_options(uint8_t* optptr, uint8_t* end);
-    uint8_t*    add_end(uint8_t* optptr);
-    void        create_msg(struct dhcps_msg* m);
+    void node_insert_to_list(list_node** phead, list_node* pinsert);
+    void node_remove_from_list(list_node** phead, list_node* pdelete);
+
+    OptionsBuffer create_msg(struct dhcps_msg* m);
+
     void        send_offer(struct dhcps_msg* m);
     void        send_nak(struct dhcps_msg* m);
     void        send_ack(struct dhcps_msg* m);
@@ -108,19 +231,22 @@ class DhcpServer
 
     netif* _netif;
 
-    struct udp_pcb*  pcb_dhcps;
-    ip_addr_t        broadcast_dhcps;
-    struct ipv4_addr server_address;
-    struct ipv4_addr client_address;
-    struct ipv4_addr dns_address;
-    uint32           dhcps_lease_time;
+    struct udp_pcb* pcb_dhcps = nullptr;
+    ip_addr_t       broadcast_dhcps {};
+    ip4_addr_t      server_address {};
+    ip4_addr_t      client_address {};
+
+    static constexpr uint32_t DefaultLeaseTime { 720 };
+    uint32_t                  lease_time = DefaultLeaseTime;
+
+    bool      offer_router = true;
+    ip_addr_t dns_address {};
+
+    dhcps_lease lease {};
 
-    struct dhcps_lease dhcps_lease;
-    list_node*         plist;
-    uint8              offer;
-    bool               renew;
+    list_node* plist = nullptr;
+    bool       renew = false;
 
-    std::vector<Option> custom_options;
     static const uint32 magic_cookie;
 };
 
diff --git a/libraries/ESP8266WiFi/examples/CustomOffer/CustomOffer.ino b/libraries/ESP8266WiFi/examples/CustomOffer/CustomOffer.ino
index cfa954ff8e..93bde55a7c 100644
--- a/libraries/ESP8266WiFi/examples/CustomOffer/CustomOffer.ino
+++ b/libraries/ESP8266WiFi/examples/CustomOffer/CustomOffer.ino
@@ -3,14 +3,13 @@
 #include <LwipDhcpServer.h>
 
 void setup() {
-    dhcpSoftAP.add_custom_offer_option(
-        DhcpServer::Option{
-            .code = 43,
-            .data = {0xca,0xfe,0xfe,0xfe,0xfe}
-        });
-    WiFi.softAP("TEST", "testtesttest");
+  dhcpSoftAP.custom_offer_options = [](const DhcpServer&, auto& options) {
+    options.add(43, { 0xca, 0xfe, 0xca, 0xfe, 0xfe });  // VENDOR is... vendor specific
+    options.add(114, "https://192.168.4.1");            // Captive portal
+  };
+  WiFi.softAP("TEST", "testtesttest");
 }
 
 void loop() {
-    delay(100);
+  delay(100);
 }
diff --git a/libraries/ESP8266WiFi/src/ESP8266WiFiAP.cpp b/libraries/ESP8266WiFi/src/ESP8266WiFiAP.cpp
index b0a0084853..f86271adc8 100644
--- a/libraries/ESP8266WiFi/src/ESP8266WiFiAP.cpp
+++ b/libraries/ESP8266WiFi/src/ESP8266WiFiAP.cpp
@@ -250,19 +250,8 @@ bool ESP8266WiFiAPClass::softAPConfig(IPAddress local_ip, IPAddress gateway, IPA
         ret = false;
     }
 
-    // set lease time to 720min --> 12h
-    if(!dhcpSoftAP.set_dhcps_lease_time(720))
-    {
-        DEBUG_WIFI("[APConfig] wifi_softap_set_dhcps_lease_time failed!\n");
-        ret = false;
-    }
-
-    uint8 mode = info.gw.addr ? 1 : 0;
-    if(!dhcpSoftAP.set_dhcps_offer_option(OFFER_ROUTER, &mode))
-    {
-        DEBUG_WIFI("[APConfig] wifi_softap_set_dhcps_offer_option failed!\n");
-        ret = false;
-    }
+    dhcpSoftAP.setLeaseTime(720); // 720 minutes == 12 h
+    dhcpSoftAP.setRouter(true); // send ROUTER option with netif's gateway IP
 
     if(!wifi_softap_dhcps_start()) {
         DEBUG_WIFI("[APConfig] wifi_softap_dhcps_start failed!\n");
diff --git a/tests/restyle.sh b/tests/restyle.sh
index 5460ca25a0..fb3df24dba 100755
--- a/tests/restyle.sh
+++ b/tests/restyle.sh
@@ -54,11 +54,13 @@ done
 # TODO should not be matched, these are formatted externally
 # exclude=$(git submodule --quiet foreach git rev-parse --show-toplevel | grep libraries)
 
-style=$(makeClangFormatStyle ${root}/tests/clang-format-arduino.yaml)
-find libraries \
-    -path libraries/ESP8266SdFat -prune -o \
-    -path libraries/Ethernet -prune -o \
-    -path libraries/SoftwareSerial -prune -o \
-    -name '*.ino' -exec $CLANG_FORMAT --verbose --style="$style" -i {} \;
+if [ -z $1 ] ; then
+    style=$(makeClangFormatStyle ${root}/tests/clang-format-arduino.yaml)
+    find libraries \
+        -path libraries/ESP8266SdFat -prune -o \
+        -path libraries/Ethernet -prune -o \
+        -path libraries/SoftwareSerial -prune -o \
+        -name '*.ino' -exec $CLANG_FORMAT --verbose --style="$style" -i {} \;
+fi
 
 #########################################
diff --git a/tools/sdk/lwip2/include/lwip/arch.h b/tools/sdk/lwip2/include/lwip/arch.h
index 58dae33aa1..16add89824 100644
--- a/tools/sdk/lwip2/include/lwip/arch.h
+++ b/tools/sdk/lwip2/include/lwip/arch.h
@@ -190,7 +190,7 @@ typedef uintptr_t mem_ptr_t;
  * sys/types or unistd.h are available).
  * Being like that, we define it to 'int' if SSIZE_MAX is not defined.
  */
-#ifdef SSIZE_MAX
+#if !defined(SSIZE_MAX) || !defined(_SSIZE_T_DECLARED)
 /* If SSIZE_MAX is defined, unistd.h should provide the type as well */
 #ifndef LWIP_NO_UNISTD_H
 #define LWIP_NO_UNISTD_H 0

From 8c79b2b89873a5962c57cac558893883c7fced0a Mon Sep 17 00:00:00 2001
From: Maxim Prokhorov <prokhorov.max@outlook.com>
Date: Tue, 31 May 2022 15:05:09 +0300
Subject: [PATCH 04/16] names

---
 cores/esp8266/LwipDhcpServer.cpp | 18 +++++++++---------
 1 file changed, 9 insertions(+), 9 deletions(-)

diff --git a/cores/esp8266/LwipDhcpServer.cpp b/cores/esp8266/LwipDhcpServer.cpp
index da36f0f368..6344722761 100644
--- a/cores/esp8266/LwipDhcpServer.cpp
+++ b/cores/esp8266/LwipDhcpServer.cpp
@@ -339,19 +339,19 @@ bool DhcpServer::add_dhcps_lease(uint8* macaddr)
     @param server -- DHCP server instance
 */
 ///////////////////////////////////////////////////////////////////////////////////
-void DhcpServer::add_offer_options(OptionsBuffer& buffer)
+void DhcpServer::add_offer_options(OptionsBuffer& options)
 {
-    buffer.add(DHCP_OPTION_SUBNET_MASK, ip_2_ip4(&_netif->netmask));
-    buffer.add(DHCP_OPTION_LEASE_TIME, lease_time);
-    buffer.add(DHCP_OPTION_SERVER_ID, ip_2_ip4(&_netif->ip_addr));
+    options.add(DHCP_OPTION_SUBNET_MASK, ip_2_ip4(&_netif->netmask));
+    options.add(DHCP_OPTION_LEASE_TIME, lease_time);
+    options.add(DHCP_OPTION_SERVER_ID, ip_2_ip4(&_netif->ip_addr));
 
     if (offer_router && !ip4_addr_isany_val(*ip_2_ip4(&_netif->gw)))
     {
-        buffer.add(DHCP_OPTION_ROUTER, ip_2_ip4(&_netif->gw));
+        options.add(DHCP_OPTION_ROUTER, ip_2_ip4(&_netif->gw));
     }
 
 #ifdef USE_DNS
-    buffer.add(DHCP_OPTION_DNS_SERVER, !ip4_addr_isany_val(*ip_2_ip4(&dns_address))
+    options.add(DHCP_OPTION_DNS_SERVER, !ip4_addr_isany_val(*ip_2_ip4(&dns_address))
                                            ? ip_2_ip4(&dns_address)
                                            : ip_2_ip4(&_netif->ip_addr));
 #endif
@@ -361,15 +361,15 @@ void DhcpServer::add_offer_options(OptionsBuffer& buffer)
         const auto  broadcast
             = ip4_addr_t { .addr = (addr->addr & ip_2_ip4(&_netif->netmask)->addr) | ~addr->addr };
 
-        buffer.add(DHCP_OPTION_BROADCAST_ADDRESS, &broadcast);
+        options.add(DHCP_OPTION_BROADCAST_ADDRESS, &broadcast);
     }
 
     // TODO: _netif->mtu ?
     static constexpr uint16_t Mtu { 1500 };
-    buffer.add(DHCP_OPTION_INTERFACE_MTU, Mtu);
+    options.add(DHCP_OPTION_INTERFACE_MTU, Mtu);
 
     static constexpr uint8_t RouterDiscovery { 0 };
-    buffer.add(DHCP_OPTION_PERFORM_ROUTER_DISCOVERY, RouterDiscovery);
+    options.add(DHCP_OPTION_PERFORM_ROUTER_DISCOVERY, RouterDiscovery);
 }
 
 ///////////////////////////////////////////////////////////////////////////////////

From 729b732c03885a4e7869aa6ff89394a9d61174cb Mon Sep 17 00:00:00 2001
From: Maxim Prokhorov <prokhorov.max@outlook.com>
Date: Tue, 31 May 2022 15:07:08 +0300
Subject: [PATCH 05/16] daisy chain

---
 cores/esp8266/LwipDhcpServer.cpp                       | 10 +++++-----
 .../ESP8266WiFi/examples/CustomOffer/CustomOffer.ino   |  4 ++--
 2 files changed, 7 insertions(+), 7 deletions(-)

diff --git a/cores/esp8266/LwipDhcpServer.cpp b/cores/esp8266/LwipDhcpServer.cpp
index 6344722761..399fbe8e67 100644
--- a/cores/esp8266/LwipDhcpServer.cpp
+++ b/cores/esp8266/LwipDhcpServer.cpp
@@ -341,9 +341,9 @@ bool DhcpServer::add_dhcps_lease(uint8* macaddr)
 ///////////////////////////////////////////////////////////////////////////////////
 void DhcpServer::add_offer_options(OptionsBuffer& options)
 {
-    options.add(DHCP_OPTION_SUBNET_MASK, ip_2_ip4(&_netif->netmask));
-    options.add(DHCP_OPTION_LEASE_TIME, lease_time);
-    options.add(DHCP_OPTION_SERVER_ID, ip_2_ip4(&_netif->ip_addr));
+    options.add(DHCP_OPTION_SUBNET_MASK, ip_2_ip4(&_netif->netmask))
+        .add(DHCP_OPTION_LEASE_TIME, lease_time)
+        .add(DHCP_OPTION_SERVER_ID, ip_2_ip4(&_netif->ip_addr));
 
     if (offer_router && !ip4_addr_isany_val(*ip_2_ip4(&_netif->gw)))
     {
@@ -352,8 +352,8 @@ void DhcpServer::add_offer_options(OptionsBuffer& options)
 
 #ifdef USE_DNS
     options.add(DHCP_OPTION_DNS_SERVER, !ip4_addr_isany_val(*ip_2_ip4(&dns_address))
-                                           ? ip_2_ip4(&dns_address)
-                                           : ip_2_ip4(&_netif->ip_addr));
+                                            ? ip_2_ip4(&dns_address)
+                                            : ip_2_ip4(&_netif->ip_addr));
 #endif
 
     {
diff --git a/libraries/ESP8266WiFi/examples/CustomOffer/CustomOffer.ino b/libraries/ESP8266WiFi/examples/CustomOffer/CustomOffer.ino
index 93bde55a7c..db5cc9099c 100644
--- a/libraries/ESP8266WiFi/examples/CustomOffer/CustomOffer.ino
+++ b/libraries/ESP8266WiFi/examples/CustomOffer/CustomOffer.ino
@@ -4,8 +4,8 @@
 
 void setup() {
   dhcpSoftAP.custom_offer_options = [](const DhcpServer&, auto& options) {
-    options.add(43, { 0xca, 0xfe, 0xca, 0xfe, 0xfe });  // VENDOR is... vendor specific
-    options.add(114, "https://192.168.4.1");            // Captive portal
+    options.add(43, { 0xca, 0xfe, 0xca, 0xfe, 0xfe })  // VENDOR is... vendor specific
+      .add(114, "https://192.168.4.1");                // Captive portal
   };
   WiFi.softAP("TEST", "testtesttest");
 }

From 811bdf9b48cf87bc7cb3ab1dd2d851e9d5362aa8 Mon Sep 17 00:00:00 2001
From: Maxim Prokhorov <prokhorov.max@outlook.com>
Date: Tue, 31 May 2022 15:12:57 +0300
Subject: [PATCH 06/16] seconds

---
 cores/esp8266/LwipDhcpServer.cpp | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/cores/esp8266/LwipDhcpServer.cpp b/cores/esp8266/LwipDhcpServer.cpp
index 399fbe8e67..f0b4613918 100644
--- a/cores/esp8266/LwipDhcpServer.cpp
+++ b/cores/esp8266/LwipDhcpServer.cpp
@@ -342,9 +342,12 @@ bool DhcpServer::add_dhcps_lease(uint8* macaddr)
 void DhcpServer::add_offer_options(OptionsBuffer& options)
 {
     options.add(DHCP_OPTION_SUBNET_MASK, ip_2_ip4(&_netif->netmask))
-        .add(DHCP_OPTION_LEASE_TIME, lease_time)
         .add(DHCP_OPTION_SERVER_ID, ip_2_ip4(&_netif->ip_addr));
 
+    // option units are seconds, while server opt is minutes
+    const uint32_t lease_time_seconds = lease_time * 60;
+    options.add(DHCP_OPTION_LEASE_TIME, lease_time_seconds);
+
     if (offer_router && !ip4_addr_isany_val(*ip_2_ip4(&_netif->gw)))
     {
         options.add(DHCP_OPTION_ROUTER, ip_2_ip4(&_netif->gw));

From 657c1e2150bf24ea0b771afa6628bc6cacc7f72f Mon Sep 17 00:00:00 2001
From: Maxim Prokhorov <prokhorov.max@outlook.com>
Date: Tue, 31 May 2022 15:34:40 +0300
Subject: [PATCH 07/16] less inline

---
 cores/esp8266/LwipDhcpServer.cpp | 25 +++++++++++++++++++++++++
 cores/esp8266/LwipDhcpServer.h   | 23 +----------------------
 2 files changed, 26 insertions(+), 22 deletions(-)

diff --git a/cores/esp8266/LwipDhcpServer.cpp b/cores/esp8266/LwipDhcpServer.cpp
index f0b4613918..e5fbb1893d 100644
--- a/cores/esp8266/LwipDhcpServer.cpp
+++ b/cores/esp8266/LwipDhcpServer.cpp
@@ -51,6 +51,7 @@
 #include "mem.h"
 
 #include <cstring>
+#include <sys/pgmspace.h>
 
 typedef struct dhcps_state
 {
@@ -172,6 +173,30 @@ int fw_has_started_softap_dhcps = 0;
 
 ////////////////////////////////////////////////////////////////////////////////////
 
+DhcpServer::OptionsBuffer& DhcpServer::OptionsBuffer::add(uint8_t code, const uint8_t* data,
+                                                          size_t size)
+{
+    if (size >= UINT8_MAX)
+    {
+        return *this;
+    }
+
+    if ((size_t)(_end - _it) < (size + 2))
+    {
+        return *this;
+    }
+
+    *_it++ = code;
+    *_it++ = size;
+
+    memcpy_P(_it, data, size);
+    _it += size;
+
+    return *this;
+}
+
+////////////////////////////////////////////////////////////////////////////////////
+
 DhcpServer::DhcpServer(netif* netif) : _netif(netif)
 {
     if (netif->num == SOFTAP_IF && fw_has_started_softap_dhcps == 1)
diff --git a/cores/esp8266/LwipDhcpServer.h b/cores/esp8266/LwipDhcpServer.h
index de1704707f..0a0876cf57 100644
--- a/cores/esp8266/LwipDhcpServer.h
+++ b/cores/esp8266/LwipDhcpServer.h
@@ -37,8 +37,6 @@
 #include <cstddef>
 #include <cstring>
 
-#include <sys/pgmspace.h>
-
 #include <array>
 #include <initializer_list>
 
@@ -49,26 +47,7 @@ class DhcpServer
     {
         OptionsBuffer(uint8_t* begin, uint8_t* end) : _it(begin), _begin(begin), _end(end) { }
 
-        OptionsBuffer& add(uint8_t code, const uint8_t* data, size_t size)
-        {
-            if (size >= UINT8_MAX)
-            {
-                return *this;
-            }
-
-            if ((size_t)(_end - _it) < (size + 2))
-            {
-                return *this;
-            }
-
-            *_it++ = code;
-            *_it++ = size;
-
-            memcpy_P(_it, data, size);
-            _it += size;
-
-            return *this;
-        }
+        OptionsBuffer& add(uint8_t code, const uint8_t* data, size_t size);
 
         OptionsBuffer& add(uint8_t code, const char* data, size_t size)
         {

From 1010b860793ca39438fa8c799adc4bee1a7fe1b8 Mon Sep 17 00:00:00 2001
From: Maxim Prokhorov <prokhorov.max@outlook.com>
Date: Tue, 31 May 2022 15:37:08 +0300
Subject: [PATCH 08/16] fix dns setter

---
 .../examples/RangeExtender-NAPT/RangeExtender-NAPT.ino     | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/libraries/ESP8266WiFi/examples/RangeExtender-NAPT/RangeExtender-NAPT.ino b/libraries/ESP8266WiFi/examples/RangeExtender-NAPT/RangeExtender-NAPT.ino
index 2c62ded038..467c65dd90 100644
--- a/libraries/ESP8266WiFi/examples/RangeExtender-NAPT/RangeExtender-NAPT.ino
+++ b/libraries/ESP8266WiFi/examples/RangeExtender-NAPT/RangeExtender-NAPT.ino
@@ -53,9 +53,10 @@ void setup() {
   }
   Serial.printf("\nSTA: %s (dns: %s / %s)\n", WiFi.localIP().toString().c_str(), WiFi.dnsIP(0).toString().c_str(), WiFi.dnsIP(1).toString().c_str());
 
-  // give DNS servers to AP side
-  dhcpSoftAP.dhcps_set_dns(0, WiFi.dnsIP(0));
-  dhcpSoftAP.dhcps_set_dns(1, WiFi.dnsIP(1));
+  // by default, DNS option will point to the interface IP
+  // instead, point it to the real DNS server
+  // (notice that only a single IP is supported)
+  dhcpSoftAP.setDns(WiFi.dnsIP(0));
 
   WiFi.softAPConfig(  // enable AP, with android-compatible google domain
     IPAddress(172, 217, 28, 254), IPAddress(172, 217, 28, 254), IPAddress(255, 255, 255, 0));

From 76a0f7ef79d813c17bbd51994c07d18801ffdaaf Mon Sep 17 00:00:00 2001
From: Maxim Prokhorov <prokhorov.max@outlook.com>
Date: Tue, 31 May 2022 20:05:00 +0300
Subject: [PATCH 09/16] might as well keep using initlist

/to d-a-v it has automatic storage, here it's the same stack based one
(just one less line for us)
---
 cores/esp8266/LwipDhcpServer.h | 17 +++++++----------
 1 file changed, 7 insertions(+), 10 deletions(-)

diff --git a/cores/esp8266/LwipDhcpServer.h b/cores/esp8266/LwipDhcpServer.h
index 0a0876cf57..09de567222 100644
--- a/cores/esp8266/LwipDhcpServer.h
+++ b/cores/esp8266/LwipDhcpServer.h
@@ -79,24 +79,21 @@ class DhcpServer
 
         OptionsBuffer& add(uint8_t code, uint8_t value)
         {
-            uint8_t buffer[] { value };
-            return add(code, buffer, sizeof(buffer));
+            return add(code, { value });
         }
 
         OptionsBuffer& add(uint8_t code, uint16_t value)
         {
-            uint8_t buffer[2] { static_cast<uint8_t>((value >> 8) & 0xff),
-                                static_cast<uint8_t>(value & 0xff) };
-            return add(code, buffer, sizeof(buffer));
+            return add(code, { static_cast<uint8_t>((value >> 8) & 0xff),
+                               static_cast<uint8_t>(value & 0xff) });
         }
 
         OptionsBuffer& add(uint8_t code, uint32_t value)
         {
-            uint8_t buffer[4] { static_cast<uint8_t>((value >> 24) & 0xff),
-                                static_cast<uint8_t>((value >> 16) & 0xff),
-                                static_cast<uint8_t>((value >> 8) & 0xff),
-                                static_cast<uint8_t>((value & 0xff)) };
-            return add(code, buffer, sizeof(buffer));
+            return add(code, { static_cast<uint8_t>((value >> 24) & 0xff),
+                               static_cast<uint8_t>((value >> 16) & 0xff),
+                               static_cast<uint8_t>((value >> 8) & 0xff),
+                               static_cast<uint8_t>((value & 0xff)) });
         }
 
         OptionsBuffer& add(uint8_t code)

From fe425cb011aeae2af496d60e44b7ed549223a2ae Mon Sep 17 00:00:00 2001
From: Maxim Prokhorov <prokhorov.max@outlook.com>
Date: Wed, 1 Jun 2022 21:01:52 +0300
Subject: [PATCH 10/16] shift blame

---
 .../examples/RangeExtender-NAPT/RangeExtender-NAPT.ino      | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/libraries/ESP8266WiFi/examples/RangeExtender-NAPT/RangeExtender-NAPT.ino b/libraries/ESP8266WiFi/examples/RangeExtender-NAPT/RangeExtender-NAPT.ino
index 467c65dd90..39121ba2e4 100644
--- a/libraries/ESP8266WiFi/examples/RangeExtender-NAPT/RangeExtender-NAPT.ino
+++ b/libraries/ESP8266WiFi/examples/RangeExtender-NAPT/RangeExtender-NAPT.ino
@@ -53,9 +53,9 @@ void setup() {
   }
   Serial.printf("\nSTA: %s (dns: %s / %s)\n", WiFi.localIP().toString().c_str(), WiFi.dnsIP(0).toString().c_str(), WiFi.dnsIP(1).toString().c_str());
 
-  // by default, DNS option will point to the interface IP
-  // instead, point it to the real DNS server
-  // (notice that only a single IP is supported)
+  // By default, DNS option will point to the interface IP
+  // Instead, point it to the real DNS server.
+  // Notice that only a single IP is supported by the DhcpServer class.
   dhcpSoftAP.setDns(WiFi.dnsIP(0));
 
   WiFi.softAPConfig(  // enable AP, with android-compatible google domain

From 135fd4a9d8501af201b1d9c10fd3a32776a87840 Mon Sep 17 00:00:00 2001
From: Maxim Prokhorov <prokhorov.max@outlook.com>
Date: Wed, 1 Jun 2022 21:12:04 +0300
Subject: [PATCH 11/16] naming

---
 cores/esp8266/LwipDhcpServer.h                   | 16 ++++++++++------
 .../examples/CustomOffer/CustomOffer.ino         |  4 ++--
 2 files changed, 12 insertions(+), 8 deletions(-)

diff --git a/cores/esp8266/LwipDhcpServer.h b/cores/esp8266/LwipDhcpServer.h
index 09de567222..2a87feb60c 100644
--- a/cores/esp8266/LwipDhcpServer.h
+++ b/cores/esp8266/LwipDhcpServer.h
@@ -111,7 +111,7 @@ class DhcpServer
         uint8_t* _end;
     };
 
-    using OfferOptionsCallback = void (*)(const DhcpServer&, OptionsBuffer&);
+    using OptionsBufferHandler = void (*)(const DhcpServer&, OptionsBuffer&);
 
     DhcpServer(netif* netif);
     ~DhcpServer();
@@ -153,15 +153,17 @@ class DhcpServer
         return lease_time;
     }
 
+    // Will use provided callback for ACK and OFFER replies
+    // `options.add(...)` to append to the options list
+    // (does not check for duplicates!)
+    void onSendOptions(OptionsBufferHandler handler) {
+        custom_offer_options = handler;
+    }
+
     bool begin(ip_info* info);
     void end();
     bool isRunning();
 
-    // Will call this on ACK and OFFER replies
-    // `options.add(...)` to append to the options list
-    // (does not check for duplicates!)
-    OfferOptionsCallback custom_offer_options = nullptr;
-
     // this is the C interface encapsulated in a class
     // (originally dhcpserver.c in lwIP-v1.4 in NonOS-SDK)
     // (not changing everything at once)
@@ -223,6 +225,8 @@ class DhcpServer
     list_node* plist = nullptr;
     bool       renew = false;
 
+    OptionsBufferHandler custom_offer_options = nullptr;
+
     static const uint32 magic_cookie;
 };
 
diff --git a/libraries/ESP8266WiFi/examples/CustomOffer/CustomOffer.ino b/libraries/ESP8266WiFi/examples/CustomOffer/CustomOffer.ino
index db5cc9099c..2c27d6f7e8 100644
--- a/libraries/ESP8266WiFi/examples/CustomOffer/CustomOffer.ino
+++ b/libraries/ESP8266WiFi/examples/CustomOffer/CustomOffer.ino
@@ -3,10 +3,10 @@
 #include <LwipDhcpServer.h>
 
 void setup() {
-  dhcpSoftAP.custom_offer_options = [](const DhcpServer&, auto& options) {
+  dhcpSoftAP.onSendOptions([](const DhcpServer&, auto& options) {
     options.add(43, { 0xca, 0xfe, 0xca, 0xfe, 0xfe })  // VENDOR is... vendor specific
       .add(114, "https://192.168.4.1");                // Captive portal
-  };
+  });
   WiFi.softAP("TEST", "testtesttest");
 }
 

From 3be2c6ed128947f5735f6439a2d985080c7b545b Mon Sep 17 00:00:00 2001
From: Maxim Prokhorov <prokhorov.max@outlook.com>
Date: Wed, 1 Jun 2022 21:17:07 +0300
Subject: [PATCH 12/16] fix impl

---
 cores/esp8266/LwipDhcpServer.cpp     |  5 -----
 cores/esp8266/LwipDhcpServer.h       |  5 ++++-
 tests/host/common/user_interface.cpp | 13 -------------
 3 files changed, 4 insertions(+), 19 deletions(-)

diff --git a/cores/esp8266/LwipDhcpServer.cpp b/cores/esp8266/LwipDhcpServer.cpp
index e5fbb1893d..2fa3bf4f12 100644
--- a/cores/esp8266/LwipDhcpServer.cpp
+++ b/cores/esp8266/LwipDhcpServer.cpp
@@ -1169,11 +1169,6 @@ void DhcpServer::dhcps_coarse_tmr(void)
     }
 }
 
-void DhcpServer::resetLeaseTime()
-{
-    lease_time = DefaultLeaseTime;
-}
-
 void DhcpServer::dhcps_client_leave(u8* bssid, struct ipv4_addr* ip, bool force)
 {
     struct dhcps_pool* pdhcps_pool = nullptr;
diff --git a/cores/esp8266/LwipDhcpServer.h b/cores/esp8266/LwipDhcpServer.h
index 2a87feb60c..ce1adbb520 100644
--- a/cores/esp8266/LwipDhcpServer.h
+++ b/cores/esp8266/LwipDhcpServer.h
@@ -141,7 +141,10 @@ class DhcpServer
         return dns_address;
     }
 
-    void resetLeaseTime();
+    void resetLeaseTime()
+    {
+        lease_time = DefaultLeaseTime;
+    }
 
     void setLeaseTime(uint32_t minutes)
     {
diff --git a/tests/host/common/user_interface.cpp b/tests/host/common/user_interface.cpp
index afb8ed3740..ddb34ffe97 100644
--- a/tests/host/common/user_interface.cpp
+++ b/tests/host/common/user_interface.cpp
@@ -49,19 +49,6 @@ bool DhcpServer::set_dhcps_lease(struct dhcps_lease* please)
     return false;
 }
 
-bool DhcpServer::set_dhcps_lease_time(uint32 minute)
-{
-    (void)minute;
-    return false;
-}
-
-bool DhcpServer::set_dhcps_offer_option(uint8 level, void* optarg)
-{
-    (void)level;
-    (void)optarg;
-    return false;
-}
-
 void DhcpServer::end() { }
 
 bool DhcpServer::begin(struct ip_info* info)

From 2312b46248e1b2d2bb439224fd419b26c608e51a Mon Sep 17 00:00:00 2001
From: Maxim Prokhorov <prokhorov.max@outlook.com>
Date: Wed, 1 Jun 2022 21:57:50 +0300
Subject: [PATCH 13/16] revert to ip4 dns

---
 cores/esp8266/LwipDhcpServer.cpp                    |  5 ++---
 cores/esp8266/LwipDhcpServer.h                      | 13 +++++++------
 .../RangeExtender-NAPT/RangeExtender-NAPT.ino       |  4 +++-
 3 files changed, 12 insertions(+), 10 deletions(-)

diff --git a/cores/esp8266/LwipDhcpServer.cpp b/cores/esp8266/LwipDhcpServer.cpp
index 2fa3bf4f12..e484df8888 100644
--- a/cores/esp8266/LwipDhcpServer.cpp
+++ b/cores/esp8266/LwipDhcpServer.cpp
@@ -379,9 +379,8 @@ void DhcpServer::add_offer_options(OptionsBuffer& options)
     }
 
 #ifdef USE_DNS
-    options.add(DHCP_OPTION_DNS_SERVER, !ip4_addr_isany_val(*ip_2_ip4(&dns_address))
-                                            ? ip_2_ip4(&dns_address)
-                                            : ip_2_ip4(&_netif->ip_addr));
+    options.add(DHCP_OPTION_DNS_SERVER,
+                !ip4_addr_isany_val(dns_address) ? &dns_address : ip_2_ip4(&_netif->ip_addr));
 #endif
 
     {
diff --git a/cores/esp8266/LwipDhcpServer.h b/cores/esp8266/LwipDhcpServer.h
index ce1adbb520..ceebbcfc63 100644
--- a/cores/esp8266/LwipDhcpServer.h
+++ b/cores/esp8266/LwipDhcpServer.h
@@ -131,12 +131,12 @@ class DhcpServer
         return offer_router;
     }
 
-    void setDns(ip_addr_t addr)
+    void setDns(ip4_addr_t addr)
     {
         dns_address = addr;
     }
 
-    ip_addr_t getDns() const
+    ip4_addr_t getDns() const
     {
         return dns_address;
     }
@@ -159,7 +159,8 @@ class DhcpServer
     // Will use provided callback for ACK and OFFER replies
     // `options.add(...)` to append to the options list
     // (does not check for duplicates!)
-    void onSendOptions(OptionsBufferHandler handler) {
+    void onSendOptions(OptionsBufferHandler handler)
+    {
         custom_offer_options = handler;
     }
 
@@ -217,11 +218,11 @@ class DhcpServer
     ip4_addr_t      server_address {};
     ip4_addr_t      client_address {};
 
-    static constexpr uint32_t DefaultLeaseTime { 720 };
+    static constexpr uint32_t DefaultLeaseTime { 720 };  // minutes
     uint32_t                  lease_time = DefaultLeaseTime;
 
-    bool      offer_router = true;
-    ip_addr_t dns_address {};
+    bool       offer_router = true;
+    ip4_addr_t dns_address {};
 
     dhcps_lease lease {};
 
diff --git a/libraries/ESP8266WiFi/examples/RangeExtender-NAPT/RangeExtender-NAPT.ino b/libraries/ESP8266WiFi/examples/RangeExtender-NAPT/RangeExtender-NAPT.ino
index 39121ba2e4..d09cea2463 100644
--- a/libraries/ESP8266WiFi/examples/RangeExtender-NAPT/RangeExtender-NAPT.ino
+++ b/libraries/ESP8266WiFi/examples/RangeExtender-NAPT/RangeExtender-NAPT.ino
@@ -55,7 +55,9 @@ void setup() {
 
   // By default, DNS option will point to the interface IP
   // Instead, point it to the real DNS server.
-  // Notice that only a single IP is supported by the DhcpServer class.
+  // Notice that:
+  // - DhcpServer class only supports IPv4
+  // - Only a single IP can be set
   dhcpSoftAP.setDns(WiFi.dnsIP(0));
 
   WiFi.softAPConfig(  // enable AP, with android-compatible google domain

From 8919f00812edbe7511e7e27d9c267ad830ad11b0 Mon Sep 17 00:00:00 2001
From: Maxim Prokhorov <prokhorov.max@outlook.com>
Date: Thu, 2 Jun 2022 21:53:08 +0300
Subject: [PATCH 14/16] merge fix

---
 cores/esp8266/LwipDhcpServer-NonOS.cpp      |  8 ++++---
 libraries/ESP8266WiFi/src/ESP8266WiFiAP.cpp | 14 ++++--------
 tests/host/common/DhcpServer.cpp            | 25 ---------------------
 3 files changed, 9 insertions(+), 38 deletions(-)

diff --git a/cores/esp8266/LwipDhcpServer-NonOS.cpp b/cores/esp8266/LwipDhcpServer-NonOS.cpp
index 0a4d1298cd..a5324ec5d5 100644
--- a/cores/esp8266/LwipDhcpServer-NonOS.cpp
+++ b/cores/esp8266/LwipDhcpServer-NonOS.cpp
@@ -71,19 +71,21 @@ extern "C"
     uint32 wifi_softap_get_dhcps_lease_time()
     {
         auto& server = getNonOSDhcpServer();
-        return server.get_dhcps_lease_time();
+        return server.getLeaseTime();
     }
 
     bool wifi_softap_set_dhcps_lease_time(uint32 minutes)
     {
         auto& server = getNonOSDhcpServer();
-        return server.set_dhcps_lease_time(minutes);
+        server.setLeaseTime(minutes);
+        return true;
     }
 
     bool wifi_softap_reset_dhcps_lease_time()
     {
         auto& server = getNonOSDhcpServer();
-        return server.reset_dhcps_lease_time();
+        server.resetLeaseTime();
+        return true;
     }
 
     bool wifi_softap_add_dhcps_lease(uint8* macaddr)
diff --git a/libraries/ESP8266WiFi/src/ESP8266WiFiAP.cpp b/libraries/ESP8266WiFi/src/ESP8266WiFiAP.cpp
index 054f00a671..2b7575d2f7 100644
--- a/libraries/ESP8266WiFi/src/ESP8266WiFiAP.cpp
+++ b/libraries/ESP8266WiFi/src/ESP8266WiFiAP.cpp
@@ -227,9 +227,8 @@ bool ESP8266WiFiAPClass::softAPConfig(IPAddress local_ip, IPAddress gateway, IPA
     info.gw.addr = gateway.v4();
     info.netmask.addr = subnet.v4();
 
-    if(!wifi_softap_dhcps_stop()) {
-        DEBUG_WIFI("[APConfig] wifi_softap_dhcps_stop failed!\n");
-    }
+    auto& server = softAPDhcpServer();
+    server.end();
 
     if(!wifi_set_ip_info(SOFTAP_IF, &info)) {
         DEBUG_WIFI("[APConfig] wifi_set_ip_info failed!\n");
@@ -247,19 +246,14 @@ bool ESP8266WiFiAPClass::softAPConfig(IPAddress local_ip, IPAddress gateway, IPA
     dhcp_lease.end_ip.addr = ip.v4();
     DEBUG_WIFI("[APConfig] DHCP IP end: %s\n", ip.toString().c_str());
 
-    auto& server = softAPDhcpServer();
     if(!server.set_dhcps_lease(&dhcp_lease))
     {
         DEBUG_WIFI("[APConfig] wifi_set_ip_info failed!\n");
         ret = false;
     }
 
-    dhcpSoftAP.setRouter(true); // send ROUTER option with netif's gateway IP
-
-    if(!wifi_softap_dhcps_start()) {
-        DEBUG_WIFI("[APConfig] wifi_softap_dhcps_start failed!\n");
-        ret = false;
-    }
+    server.setRouter(true); // send ROUTER option with netif's gateway IP
+    server.begin();
 
     // check config
     if(wifi_get_ip_info(SOFTAP_IF, &info)) {
diff --git a/tests/host/common/DhcpServer.cpp b/tests/host/common/DhcpServer.cpp
index 7e88ea88c4..a6038e5826 100644
--- a/tests/host/common/DhcpServer.cpp
+++ b/tests/host/common/DhcpServer.cpp
@@ -13,19 +13,6 @@ bool DhcpServer::set_dhcps_lease(struct dhcps_lease* please)
     return false;
 }
 
-bool DhcpServer::set_dhcps_lease_time(uint32 minute)
-{
-    (void)minute;
-    return false;
-}
-
-bool DhcpServer::set_dhcps_offer_option(uint8 level, void* optarg)
-{
-    (void)level;
-    (void)optarg;
-    return false;
-}
-
 void DhcpServer::end() { }
 
 bool DhcpServer::begin()
@@ -65,16 +52,4 @@ extern "C"
         return true;
     }
 
-    bool wifi_softap_set_dhcps_lease_time(uint32 minute)
-    {
-        (void)minute;
-        return true;
-    }
-
-    bool wifi_softap_set_dhcps_offer_option(uint8 level, void* optarg)
-    {
-        (void)level;
-        (void)optarg;
-        return true;
-    }
 }

From ad7faf70b877e6dedee8eba863be7bf8c91eec01 Mon Sep 17 00:00:00 2001
From: Maxim Prokhorov <prokhorov.max@outlook.com>
Date: Tue, 7 Jun 2022 22:29:31 +0300
Subject: [PATCH 15/16] restyle

---
 cores/esp8266/LwipDhcpServer.h                      |  2 +-
 .../examples/CustomOffer/CustomOffer.ino            | 13 +++++++++----
 tests/host/common/DhcpServer.cpp                    |  1 -
 3 files changed, 10 insertions(+), 6 deletions(-)

diff --git a/cores/esp8266/LwipDhcpServer.h b/cores/esp8266/LwipDhcpServer.h
index 96d8af357b..152e54c9e6 100644
--- a/cores/esp8266/LwipDhcpServer.h
+++ b/cores/esp8266/LwipDhcpServer.h
@@ -220,7 +220,7 @@ class DhcpServer
     ip4_addr_t      server_address {};
     ip4_addr_t      client_address {};
 
-    uint32_t        lease_time = DefaultLeaseTime;
+    uint32_t lease_time = DefaultLeaseTime;
 
     bool       offer_router = true;
     ip4_addr_t dns_address {};
diff --git a/libraries/ESP8266WiFi/examples/CustomOffer/CustomOffer.ino b/libraries/ESP8266WiFi/examples/CustomOffer/CustomOffer.ino
index 2c27d6f7e8..fa746277c9 100644
--- a/libraries/ESP8266WiFi/examples/CustomOffer/CustomOffer.ino
+++ b/libraries/ESP8266WiFi/examples/CustomOffer/CustomOffer.ino
@@ -1,11 +1,16 @@
 #include <Arduino.h>
 #include <ESP8266WiFi.h>
-#include <LwipDhcpServer.h>
 
 void setup() {
-  dhcpSoftAP.onSendOptions([](const DhcpServer&, auto& options) {
-    options.add(43, { 0xca, 0xfe, 0xca, 0xfe, 0xfe })  // VENDOR is... vendor specific
-      .add(114, "https://192.168.4.1");                // Captive portal
+  auto& server = WiFi.softAPDhcpServer();
+  server.onSendOptions([](const DhcpServer& server, auto& options) {
+    // VENDOR is... vendor specific
+    options.add(43, { 0xca, 0xfe, 0xca, 0xfe, 0xfe });
+
+    // Captive Portal URI
+    const IPAddress gateway = netif_ip4_addr(server.getNetif());
+    const String captive = F("http://") + gateway.toString();
+    options.add(114, captive.c_str(), captive.length());
   });
   WiFi.softAP("TEST", "testtesttest");
 }
diff --git a/tests/host/common/DhcpServer.cpp b/tests/host/common/DhcpServer.cpp
index a6038e5826..c4f9dd158b 100644
--- a/tests/host/common/DhcpServer.cpp
+++ b/tests/host/common/DhcpServer.cpp
@@ -51,5 +51,4 @@ extern "C"
         (void)please;
         return true;
     }
-
 }

From f9de275e30dd599292d0f3b825429274fa3a61fa Mon Sep 17 00:00:00 2001
From: Maxim Prokhorov <prokhorov.max@outlook.com>
Date: Thu, 9 Jun 2022 00:05:46 +0300
Subject: [PATCH 16/16] masking done wrong

---
 cores/esp8266/LwipDhcpServer.cpp | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/cores/esp8266/LwipDhcpServer.cpp b/cores/esp8266/LwipDhcpServer.cpp
index 25ebf4e36e..ddae5dd4fe 100644
--- a/cores/esp8266/LwipDhcpServer.cpp
+++ b/cores/esp8266/LwipDhcpServer.cpp
@@ -364,9 +364,9 @@ void DhcpServer::add_offer_options(OptionsBuffer& options)
 #endif
 
     {
-        const auto* addr = ip_2_ip4(&_netif->ip_addr);
-        const auto  broadcast
-            = ip4_addr_t { .addr = (addr->addr & ip_2_ip4(&_netif->netmask)->addr) | ~addr->addr };
+        const auto* addr      = ip_2_ip4(&_netif->ip_addr);
+        const auto* mask      = ip_2_ip4(&_netif->netmask);
+        const auto  broadcast = ip4_addr_t { .addr = (addr->addr & mask->addr) | ~mask->addr };
 
         options.add(DHCP_OPTION_BROADCAST_ADDRESS, &broadcast);
     }