From 7fd6ec42b63390702ff5c7b0422c1aa487e0c100 Mon Sep 17 00:00:00 2001
From: Walter Stanish <505366+globalcitizen@users.noreply.github.com>
Date: Mon, 21 Feb 2022 11:24:26 +0800
Subject: [PATCH] Add option to exclude DNS features.

---
 src/EtherCard.cpp | 2 ++
 src/EtherCard.h   | 6 ++++++
 src/dns.cpp       | 2 ++
 src/tcpip.cpp     | 8 ++++++++
 4 files changed, 18 insertions(+)

diff --git a/src/EtherCard.cpp b/src/EtherCard.cpp
index f752a9bf..9b72d8c8 100644
--- a/src/EtherCard.cpp
+++ b/src/EtherCard.cpp
@@ -21,7 +21,9 @@ uint8_t EtherCard::netmask[IP_LEN]; // subnet mask
 uint8_t EtherCard::broadcastip[IP_LEN]; // broadcast address
 uint8_t EtherCard::gwip[IP_LEN];   // gateway
 uint8_t EtherCard::dhcpip[IP_LEN]; // dhcp server
+#if ETHERCARD_DNS
 uint8_t EtherCard::dnsip[IP_LEN];  // dns server
+#endif
 uint8_t EtherCard::hisip[IP_LEN];  // ip address of remote host
 uint16_t EtherCard::hisport = HTTP_PORT; // tcp port to browse to
 bool EtherCard::using_dhcp = false;
diff --git a/src/EtherCard.h b/src/EtherCard.h
index 703b5990..fd3f5868 100644
--- a/src/EtherCard.h
+++ b/src/EtherCard.h
@@ -49,6 +49,12 @@
 */
 #define ETHERCARD_DHCP 1
 
+/** Enable DNS.
+*   Setting this to zero disables the use of DNS; if a program uses DNS it will
+*   not compile. Saves 6 bytes SRAM, 110 bytes flash, and some packet processing overhead.
+*/
+#define ETHERCARD_DNS 1
+
 /** Enable client connections.
 * Setting this to zero means that the program cannot issue TCP client requests
 * anymore. Compilation will still work but the request will never be
diff --git a/src/dns.cpp b/src/dns.cpp
index 3909c6a0..237dd57b 100644
--- a/src/dns.cpp
+++ b/src/dns.cpp
@@ -4,6 +4,7 @@
 //
 // 2010-05-20 <jc@wippler.nl>
 
+#if ETHERCARD_DNS
 #include "EtherCard.h"
 #include "net.h"
 
@@ -118,3 +119,4 @@ bool EtherCard::dnsLookup (const char* name, bool fromRam) {
 
     return true;
 }
+#endif
diff --git a/src/tcpip.cpp b/src/tcpip.cpp
index 6dbd0957..e39087e7 100644
--- a/src/tcpip.cpp
+++ b/src/tcpip.cpp
@@ -50,8 +50,10 @@ static const char *client_urlbuf_var; // Pointer to c-string filename part of HT
 static const char *client_hoststr; // Pointer to c-string hostname of current HTTP request
 static void (*icmp_cb)(uint8_t *ip); // Pointer to callback function for ICMP ECHO response handler (triggers when localhost receives ping response (pong))
 static uint8_t destmacaddr[ETH_LEN]; // storing both dns server and destination mac addresses, but at different times because both are never needed at same time.
+#if ETHERCARD_DNS
 static boolean waiting_for_dns_mac = false; //might be better to use bit flags and bitmask operations for these conditions
 static boolean has_dns_mac = false;
+#endif
 static boolean waiting_for_dest_mac = false;
 static boolean has_dest_mac = false;
 static uint8_t gwmacaddr[ETH_LEN]; // Hardware (MAC) address of gateway router
@@ -459,11 +461,13 @@ uint8_t EtherCard::clientWaitingGw () {
     return !(waitgwmac & WGW_HAVE_GW_MAC);
 }
 
+#if ETHERCARD_DNS
 uint8_t EtherCard::clientWaitingDns () {
     if(is_lan(myip, dnsip))
         return !has_dns_mac;
     return !(waitgwmac & WGW_HAVE_GW_MAC);
 }
+#endif
 
 static uint8_t client_store_mac(uint8_t *source_ip, uint8_t *mac) {
     if (memcmp(gPB + ETH_ARP_SRC_IP_P, source_ip, IP_LEN) != 0)
@@ -697,11 +701,13 @@ uint16_t EtherCard::packetLoop (uint16_t plen) {
         }
 #endif
 
+#if ETHERCARD_DNS
         //!@todo this is trying to find mac only once. Need some timeout to make another call if first one doesn't succeed.
         if(is_lan(myip, dnsip) && !has_dns_mac && !waiting_for_dns_mac) {
             client_arp_whohas(dnsip);
             waiting_for_dns_mac = true;
         }
+#endif
 
         //!@todo this is trying to find mac only once. Need some timeout to make another call if first one doesn't succeed.
         if(is_lan(myip, hisip) && !has_dest_mac && !waiting_for_dest_mac) {
@@ -718,10 +724,12 @@ uint16_t EtherCard::packetLoop (uint16_t plen) {
             make_arp_answer_from_request();
         if (waitgwmac & WGW_ACCEPT_ARP_REPLY && (gPB[ETH_ARP_OPCODE_L_P]==ETH_ARP_OPCODE_REPLY_L_V) && client_store_mac(gwip, gwmacaddr))
             waitgwmac = WGW_HAVE_GW_MAC;
+#if ETHERCARD_DNS
         if (!has_dns_mac && waiting_for_dns_mac && client_store_mac(dnsip, destmacaddr)) {
             has_dns_mac = true;
             waiting_for_dns_mac = false;
         }
+#endif
         if (!has_dest_mac && waiting_for_dest_mac && client_store_mac(hisip, destmacaddr)) {
             has_dest_mac = true;
             waiting_for_dest_mac = false;