WiFiServer IPv6 support and example, WiFiClient::remoteIP IPv6 support

This is one of useful examples of IPv6, such device can be reached
from internet without any port forward on NAT and etc.

Most of changes for WiFiServer is to use ip6 structures, and for ip4
we use ipv6-to-ipv4 mapped addresses (RFC 4291).
For RemoteIP i added support ip4 to ip6 mapping as well.

Scenarios tested:
wifiMulti.IPv6(true); but set to listen on IPv4 only
IPv6 disabled, with or without bind to specific IP4
AsyncUDPServer without IPv6 support, to check if remoteIP works properly

Signed-off-by: Denys Fedoryshchenko <[email protected]>

Author: nuclearcat

Diff for: libraries/WiFi/examples/WiFiTelnetToSerial/WiFiTelnetToSerial.ino

@@ -35,6 +35,7 @@ void setup() {
   Serial.begin(115200);
   Serial.println("\nConnecting");
 
+  wifiMulti.IPv6(true);
   wifiMulti.addAP(ssid, password);
   wifiMulti.addAP("ssid_from_AP_2", "your_password_for_AP_2");
   wifiMulti.addAP("ssid_from_AP_3", "your_password_for_AP_3");

Diff for: libraries/WiFi/src/WiFiClient.cpp

@@ -561,8 +561,28 @@ IPAddress WiFiClient::remoteIP(int fd) const
     struct sockaddr_storage addr;
     socklen_t len = sizeof addr;
     getpeername(fd, (struct sockaddr*)&addr, &len);
-    struct sockaddr_in *s = (struct sockaddr_in *)&addr;
-    return IPAddress((uint32_t)(s->sin_addr.s_addr));
+
+    // Old way, IPv4
+    if (((struct sockaddr*)&addr)->sa_family == AF_INET) {
+        struct sockaddr_in *s = (struct sockaddr_in *)&addr;
+        return IPAddress((uint32_t)(s->sin_addr.s_addr));
+    }
+    // IPv6, but it might be IPv4 mapped address
+    if (((struct sockaddr*)&addr)->sa_family == AF_INET6) {
+        struct sockaddr_in6 *saddr6 = (struct sockaddr_in6 *)&addr;
+        if (IN6_IS_ADDR_V4MAPPED(saddr6->sin6_addr.un.u32_addr)) {
+            struct sockaddr_in addr4;
+            memset(&addr4, 0, sizeof(addr4));
+            addr4.sin_family = AF_INET;
+            addr4.sin_port = saddr6->sin6_port;
+            memcpy(&addr4.sin_addr.s_addr, saddr6->sin6_addr.s6_addr+12, sizeof(addr4.sin_addr.s_addr));
+            return IPAddress((uint32_t)(addr4.sin_addr.s_addr));
+        }
+        log_e("WiFiClient::remoteIP IPv6 not supported yet");
+        return (IPAddress(0,0,0,0));
+    }
+    log_e("WiFiClient::remoteIP Not AF_INET or AF_INET6?");
+    return (IPAddress(0,0,0,0));
 }
 
 uint16_t WiFiClient::remotePort(int fd) const

Diff for: libraries/WiFi/src/WiFiClient.h

@@ -106,4 +106,9 @@ class WiFiClient : public ESPLwIPClient
     using Print::write;
 };
 
+#define IN6_IS_ADDR_V4MAPPED(a) \
+        ((((__const uint32_t *) (a))[0] == 0)                                 \
+         && (((__const uint32_t *) (a))[1] == 0)                              \
+         && (((__const uint32_t *) (a))[2] == htonl (0xffff)))
+
 #endif /* _WIFICLIENT_H_ */

Diff for: libraries/WiFi/src/WiFiServer.cpp

@@ -47,8 +47,8 @@ WiFiClient WiFiServer::available(){
     _accepted_sockfd = -1;
   }
   else {
-  struct sockaddr_in _client;
-  int cs = sizeof(struct sockaddr_in);
+  struct sockaddr_in6 _client;
+  int cs = sizeof(struct sockaddr_in6);
 #ifdef ESP_IDF_VERSION_MAJOR
     client_sock = lwip_accept(sockfd, (struct sockaddr *)&_client, (socklen_t*)&cs);
 #else
@@ -76,14 +76,14 @@ void WiFiServer::begin(uint16_t port, int enable){
   if(port){
       _port = port;
   }
-  struct sockaddr_in server;
-  sockfd = socket(AF_INET , SOCK_STREAM, 0);
+  struct sockaddr_in6 server;
+  sockfd = socket(AF_INET6 , SOCK_STREAM, 0);
   if (sockfd < 0)
     return;
   setsockopt(sockfd, SOL_SOCKET, SO_REUSEADDR, &enable, sizeof(int));
-  server.sin_family = AF_INET;
-  server.sin_addr.s_addr = _addr;
-  server.sin_port = htons(_port);
+  server.sin6_family = AF_INET6;
+  server.sin6_addr = _addr;
+  server.sin6_port = htons(_port);
   if(bind(sockfd, (struct sockaddr *)&server, sizeof(server)) < 0)
     return;
   if(listen(sockfd , _max_clients) < 0)
@@ -106,8 +106,8 @@ bool WiFiServer::hasClient() {
     if (_accepted_sockfd >= 0) {
       return true;
     }
-    struct sockaddr_in _client;
-    int cs = sizeof(struct sockaddr_in);
+    struct sockaddr_in6 _client;
+    int cs = sizeof(struct sockaddr_in6);
 #ifdef ESP_IDF_VERSION_MAJOR
     _accepted_sockfd = lwip_accept(sockfd, (struct sockaddr *)&_client, (socklen_t*)&cs);
 #else

Diff for: libraries/WiFi/src/WiFiServer.h

@@ -23,12 +23,14 @@
 #include "Server.h"
 #include "WiFiClient.h"
 #include "IPAddress.h"
+#include "lwip/inet.h"
+#include "lwip/netdb.h"
 
 class WiFiServer : public Server {
   private:
     int sockfd;
     int _accepted_sockfd = -1;
-    IPAddress _addr;
+    in6_addr _addr;
     uint16_t _port;
     uint8_t _max_clients;
     bool _listening;
@@ -37,12 +39,19 @@ class WiFiServer : public Server {
   public:
     void listenOnLocalhost(){}
 
-    // _addr(INADDR_ANY) is the same as _addr() ==> 0.0.0.0
-    WiFiServer(uint16_t port=80, uint8_t max_clients=4):sockfd(-1),_accepted_sockfd(-1),_addr(),_port(port),_max_clients(max_clients),_listening(false),_noDelay(false) {
+    WiFiServer(uint16_t port=80, uint8_t max_clients=4):sockfd(-1),_accepted_sockfd(-1),_port(port),_max_clients(max_clients),_listening(false),_noDelay(false) {
       log_v("WiFiServer::WiFiServer(port=%d, ...)", port);
+      _addr = IN6ADDR_ANY_INIT;
     }
-    WiFiServer(const IPAddress& addr, uint16_t port=80, uint8_t max_clients=4):sockfd(-1),_accepted_sockfd(-1),_addr(addr),_port(port),_max_clients(max_clients),_listening(false),_noDelay(false) {
+    WiFiServer(const IPAddress& addr, uint16_t port=80, uint8_t max_clients=4):sockfd(-1),_accepted_sockfd(-1),_port(port),_max_clients(max_clients),_listening(false),_noDelay(false) {
       log_v("WiFiServer::WiFiServer(addr=%s, port=%d, ...)", addr.toString().c_str(), port);
+      char buffer[64] = { 0 };
+      // Print IPv4 in IPv6 notation
+      sprintf(buffer, "::FFFF:%s", addr.toString().c_str());
+      int rc = inet_pton(AF_INET6, buffer, &_addr);
+      if (rc != 1) {
+        log_e("WiFiServer::WiFiServer unable to resolve address, rc=%d", rc);
+      }
     }
     ~WiFiServer(){ end();}
     WiFiClient available();