Adds a C library alternative to the ircbot nudge script.

This allows for more secure and stable transmission on Linux, but you might see some improvements on Windows too.
Code lies in (confusingly) lib/src.
nudge.c should be compiled to lib/nudge.[dll/so] and be linked against netutil.c.

There's some horribly hacky code in nudge.c to assemble pickled data, but it's probably the fastest way that's still safe.

Signed-off-by: Mloc-Argent <colmohici@gmail.com>

lib/DLLSocket/main.cpp

@@ -0,0 +1,133 @@
+// OS-specific networking includes
+// -------------------------------
+#ifdef __WIN32
+    #include <winsock2.h>
+    typedef int socklen_t;
+#else
+    extern "C" {
+    #include <sys/types.h>
+    #include <sys/socket.h>
+    #include <netinet/in.h>
+    #include <arpa/inet.h>
+    #include <netdb.h>
+    #include <fcntl.h>
+    #include <stdlib.h>
+    #include <string.h>
+    }
+
+    typedef int SOCKET;
+    typedef sockaddr_in SOCKADDR_IN;
+    typedef sockaddr SOCKADDR;
+    #define SOCKET_ERROR -1
+#endif
+
+// Socket used for all communications
+SOCKET sock;
+
+// Address of the remote server
+SOCKADDR_IN addr;
+
+// Buffer used to return dynamic strings to the caller
+#define BUFFER_SIZE 1024
+char return_buffer[BUFFER_SIZE];
+
+// exposed functions
+// ------------------------------
+
+const char* SUCCESS = "1\0"; // string representing success
+
+#ifdef __WIN32
+    #define DLL_EXPORT __declspec(dllexport)
+#else
+    #define DLL_EXPORT __attribute__ ((visibility ("default")))
+#endif
+
+// arg1: ip(in the xx.xx.xx.xx format)
+// arg2: port(a short)
+// return: NULL on failure, SUCCESS otherwise
+extern "C" DLL_EXPORT const char* establish_connection(int n, char *v[])
+{
+    // extract args
+    // ------------
+    if(n < 2) return 0;
+    const char* ip = v[0];
+    const char* port_s = v[1];
+    unsigned short port = atoi(port_s);
+
+    // set up network stuff
+    // --------------------
+    #ifdef __WIN32
+        WSADATA wsa;
+        WSAStartup(MAKEWORD(2,0),&wsa);
+    #endif
+    sock = socket(AF_INET,SOCK_DGRAM,0);
+
+    // make the socket non-blocking
+    // ----------------------------
+    #ifdef __WIN32
+        unsigned long iMode=1;
+        ioctlsocket(sock,FIONBIO,&iMode);
+    #else
+        fcntl(sock, F_SETFL, O_NONBLOCK);
+    #endif
+
+    // establish a connection to the server
+    // ------------------------------------
+    memset(&addr,0,sizeof(SOCKADDR_IN));
+    addr.sin_family=AF_INET;
+    addr.sin_port=htons(port);
+
+    // convert the string representation of the ip to a byte representation
+    addr.sin_addr.s_addr=inet_addr(ip);
+
+    return SUCCESS;
+}
+
+// arg1: string message to send
+// return: NULL on failure, SUCCESS otherwise
+extern "C" DLL_EXPORT const char* send_message(int n, char *v[])
+{
+    // extract the args
+    if(n < 1) return 0;
+    const char* msg = v[0];
+
+    // send the message
+    int rc = sendto(sock,msg,strlen(msg),0,(SOCKADDR*)&addr,sizeof(SOCKADDR));
+
+    // check for errors
+    if (rc != -1) {
+       return SUCCESS;
+    }
+    else {
+       return 0;
+    }
+}
+
+// no args
+// return: message if any received, NULL otherwise
+extern "C" DLL_EXPORT const char* recv_message(int n, char *v[])
+{
+    SOCKADDR_IN sender; // we will store the sender address here
+
+    socklen_t sender_byte_length = sizeof(sender);
+
+    // Try receiving messages until we receive one that's valid, or there are no more messages
+    while(1) {
+        int rc = recvfrom(sock, return_buffer, BUFFER_SIZE,0,(SOCKADDR*) &sender,&sender_byte_length);
+        if(rc > 0) {
+            // we could read something
+
+            if(sender.sin_addr.s_addr != addr.sin_addr.s_addr) {
+                continue; // not our connection, ignore and try again
+            } else {
+                return_buffer[rc] = 0; // 0-terminate the string
+                return return_buffer;
+            }
+        }
+        else {
+            break; // no more messages, stop trying to receive
+        }
+    }
+
+    return 0;
+}