WiFiClient::remoteIP and remoteIP6 IPv6 support

For RemoteIP and AF_INET6 socket i added support ip6 to ip4 mapping,
so .remoteIP will return IPv4 address on dual stack socket, if available.

Scenarios tested:
WiFiTelnetToSerial, wifiMulti.IPv6(true), connect both from IPv4 and IPv6
WiFiTelnetToSerial, wifiMulti.IPv6(true); but set to listen on IPv4 only.
WiFiTelnetToSerial, IPv6 disabled, with or without bind to specific IP4.
AsyncUDPServer, without IPv6 support.

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

Author: nuclearcat

Diff for: cores/esp32/Client.h

@@ -22,6 +22,7 @@
 #include "Print.h"
 #include "Stream.h"
 #include "IPAddress.h"
+#include "IPv6Address.h"
 
 class Client: public Stream
 {

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

@@ -561,8 +561,52 @@ 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 to IPv4 cannot convert");
+        return (IPAddress(0,0,0,0));
+    }
+    log_e("WiFiClient::remoteIP Not AF_INET or AF_INET6?");
+    return (IPAddress(0,0,0,0));
+}
+
+IPv6Address WiFiClient::remoteIP6(int fd) const
+{
+    struct sockaddr_storage addr;
+    socklen_t len = sizeof addr;
+    getpeername(fd, (struct sockaddr*)&addr, &len);
+
+    // IPv4 socket we can print as IPv6 mapped
+    if (((struct sockaddr*)&addr)->sa_family == AF_INET) {
+        uint8_t buffer[16] = { 0 };
+        buffer[10] = 0xFF;
+        buffer[11] = 0xFF;
+        struct sockaddr_in *s = (struct sockaddr_in *)&addr;
+        memcpy(&buffer[12], (uint8_t*)&s->sin_addr.s_addr, 4);
+        return IPv6Address(buffer);
+    }
+    // IPv6
+    if (((struct sockaddr*)&addr)->sa_family == AF_INET6) {
+        struct sockaddr_in6 *saddr6 = (struct sockaddr_in6 *)&addr;
+        return (IPv6Address(saddr6->sin6_addr.s6_addr));
+    }
+    log_e("WiFiClient::remoteIP Not AF_INET or AF_INET6?");
+    return (IPv6Address());
 }
 
 uint16_t WiFiClient::remotePort(int fd) const
@@ -579,6 +623,11 @@ IPAddress WiFiClient::remoteIP() const
     return remoteIP(fd());
 }
 
+IPv6Address WiFiClient::remoteIP6() const
+{
+    return remoteIP6(fd());
+}
+
 uint16_t WiFiClient::remotePort() const
 {
     return remotePort(fd());

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

@@ -95,6 +95,8 @@ class WiFiClient : public ESPLwIPClient
 
     IPAddress remoteIP() const;
     IPAddress remoteIP(int fd) const;
+    IPv6Address remoteIP6() const;
+    IPv6Address remoteIP6(int fd) const;    
     uint16_t remotePort() const;
     uint16_t remotePort(int fd) const;
     IPAddress localIP() const;
@@ -106,4 +108,9 @@ 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/WiFiMulti.cpp

@@ -30,7 +30,6 @@
 
 WiFiMulti::WiFiMulti()
 {
-    ipv6_support = false;
 }
 
 WiFiMulti::~WiFiMulti()