Async support (#16)

* Added set/getNoDelay() and hasClient() for ESPAsyncWebServer compat

* Added write(adr, len) for ArduinoECCX08

* Added getMode() and mode() for better ESP32 compatibility

* Added an Apple-compatible implementation of defaultInterface()

using sysctl(), since MacOS does not have /proc
Also fixed a problem in the /proc implementation, which left
a dangling open file descriptor.

Author: MitchBradley

ArduinoCore-Linux/cores/arduino/EthernetServer.h

@@ -39,6 +39,8 @@ class EthernetServer : public Server {
   struct sockaddr_in server_addr;
   int _status = wl_status_t::WL_DISCONNECTED;
   bool is_blocking = false;
+  bool _noDelay = false;
+
   static std::vector<EthernetServer*>& active_servers() {
     static std::vector<EthernetServer*> servers;
     return servers;
@@ -102,6 +104,19 @@ class EthernetServer : public Server {
   }
   int status() { return _status; }
 
+  // The following are for compatibility with ESP32 WiFiServer
+  // get/setNoDelay maintain the state variable, but otherwise
+  // have no effect on the code.
+  void setNoDelay(bool nodelay) { _noDelay = nodelay; }
+  bool getNoDelay() { return _noDelay; }
+  bool hasClient() {
+    if (server_fd <= 0) return false;
+    struct pollfd pfd;
+    pfd.fd = server_fd;
+    pfd.events = POLLIN;
+    return ::poll(&pfd, 1, 0) > 0 && (pfd.revents & POLLIN);
+  }
+
   using Print::write;
 
  protected:
@@ -149,6 +164,8 @@ class EthernetServer : public Server {
       return false;
     }
 
+    _noDelay = false;
+
     // Add to active servers list for signal handling
     active_servers().push_back(this);
     _status = wl_status_t::WL_CONNECTED;

ArduinoCore-Linux/cores/arduino/I2CWrapper.cpp

@@ -98,6 +98,17 @@ void I2CWrapper::onReceive(void (*)(int)) {}
 
 void I2CWrapper::onRequest(void (*)(void)) {}
 
+size_t I2CWrapper::write(const uint8_t* data, size_t len) {
+  int cnt = len;
+  while (cnt) {
+    if (!write(*data++)) {
+      return len - cnt;
+    }
+    --cnt;
+  }
+  return len;
+}
+
 size_t I2CWrapper::write(uint8_t data) {
   HardwareI2C* i2c = getI2C();
   if (i2c != nullptr) {

ArduinoCore-Linux/cores/arduino/I2CWrapper.h

@@ -66,6 +66,7 @@ class I2CWrapper : public HardwareI2C {
   void onReceive(void (*)(int));
   void onRequest(void (*)(void));
   size_t write(uint8_t);
+  size_t write(const uint8_t *, size_t);
   int available();
   int read();
   int peek();

ArduinoCore-Linux/cores/arduino/SocketImpl.cpp

@@ -30,6 +30,10 @@
 #include <sys/socket.h>
 #include <sys/types.h>
 #include <unistd.h>
+#ifdef __APPLE__
+#include <net/route.h>
+#include <sys/sysctl.h>
+#endif
 
 #include <cstring>
 
@@ -138,11 +142,55 @@ void SocketImpl::close() {
   ::close(sock);
 }
 
+#ifndef __APPLE__
+// The sysctl() method of getting the routing table information also
+// works in Linux, but is deprecated there.
+static char *defaultInterface() {
+  int mib[] = {CTL_NET, PF_ROUTE, 0, AF_INET, NET_RT_FLAGS, RTF_GATEWAY};
+  size_t needed = 0;
+
+  if (sysctl(mib, 6, NULL, &needed, NULL, 0) < 0 || needed == 0)
+    return nullptr;
+
+  char *buf = (char *)malloc(needed);
+  if (!buf) return nullptr;
+
+  if (sysctl(mib, 6, buf, &needed, NULL, 0) < 0) {
+    free(buf);
+    return nullptr;
+  }
+
+  static char ifname[IF_NAMESIZE];
+  char *result = nullptr;
+
+  for (char *p = buf; p < buf + needed;) {
+    struct rt_msghdr *rtm = (struct rt_msghdr *)p;
+    struct sockaddr *sa = (struct sockaddr *)(rtm + 1);
+    if (sa->sa_family == AF_INET) {
+      struct sockaddr_in *sin = (struct sockaddr_in *)sa;
+      if (sin->sin_addr.s_addr == INADDR_ANY) {
+        if (if_indextoname(rtm->rtm_index, ifname) != nullptr) {
+          Logger.info("Default network interface is ", ifname);
+          result = ifname;
+        }
+        break;
+      }
+    }
+    p += rtm->rtm_msglen;
+  }
+
+  free(buf);
+  return result;
+}
+#else
 char *defaultInterface() {
   FILE *f;
   char line[100], *p, *c;
 
   f = fopen("/proc/net/route", "r");
+  if (!f) {
+    return nullptr;
+  }
 
   while (fgets(line, 100, f)) {
     p = strtok(line, " \t");
@@ -153,12 +201,15 @@ char *defaultInterface() {
         static char defaultInterface[20];
         strcpy(defaultInterface, p);
         Logger.info("Default network interface is ", p);
+        fclose(f);
         return defaultInterface;
       }
     }
   }
+  fclose(f);
   return nullptr;
 }
+#endif
 
 // determines the IP Adress
 const char *SocketImpl::getIPAddress() {

ArduinoCore-Linux/cores/arduino/WiFi.h

@@ -31,6 +31,8 @@
 
 namespace arduino {
 
+typedef enum { WIFI_OFF = 0, WIFI_STA = 1, WIFI_AP = 2, WIFI_AP_STA = 3 } WiFiMode_t;  // For ESP compatibility
+
 enum wifi_ps_type_t { WIFI_PS_NONE, WIFI_PS_MIN_MODEM, WIFI_PS_MAX_MODEM };
 
 class WifiMock {
@@ -56,6 +58,10 @@ class WifiMock {
 
   void setClientInsecure() {}
 
+  // WIFI_STA is the best approximation to interface enabled
+  void mode(WiFiMode_t m);
+  WiFiMode_t getMode() { return WIFI_STA; };
+
  protected:
   IPAddress adress;
   int mac = 0;