requesting and receiving rref

but currently the value is buggy

Makefile

@@ -1,10 +1,13 @@
 BIN=bin
 
-all: dirs command
+all: dirs command readref
 
-command: command.c
+command:
 	gcc -o ${BIN}/command network.c command.c
 
+readref:
+	gcc -o ${BIN}/readref network.c readref.c
+
 .PHONY: clean dirs
 clean:
 	rm -rf ${BIN}

command.c

@@ -14,13 +14,13 @@ int main(int argc, char *argv[]) {
 	}
 
 	// network
-	xPlaneSocket = connectXPlane(SERVER, PORT);
+	xPlaneSocket = connectXPlane(DEST_SERVER, DEST_PORT, SRC_PORT);
 	if (xPlaneSocket < 0) {
 		exit(EXIT_FAILURE);
 	}
 
 	// send payload
-	if (sendToXPlane(xPlaneSocket, "CMND", argv[1]) < 0) {
+	if (sendToXPlane(xPlaneSocket, "CMND", argv[1], strlen(argv[1])) < 0) {
 		exit(EXIT_FAILURE);
 	}
 

network.c

@@ -15,7 +15,7 @@
 const int DGRAM_MSG_START = 0;
 const int DGRAM_PAYLOAD_START = DGRAM_MSG_START + DGRAM_MSG_LENGTH + DGRAM_NULL_LENGTH;
 
-int sendToXPlane(int sock, char *msg, char *payload) {
+int sendToXPlane(int sock, char *msg, void *payload, int lengthOfPayload) {
 	char bytesToSend[SEND_BUFFER];
 	memset(bytesToSend, 0, SEND_BUFFER);
 
@@ -25,14 +25,14 @@ int sendToXPlane(int sock, char *msg, char *payload) {
 	}
 
 	// payload shouldn't exceed buffer
-	if (strlen(payload) > (SEND_BUFFER - DGRAM_MSG_LENGTH - DGRAM_NULL_LENGTH)) {
+	if (lengthOfPayload > (SEND_BUFFER - DGRAM_MSG_LENGTH - DGRAM_NULL_LENGTH)) {
 		return -11;
 	}
 
 	strcpy(&bytesToSend[DGRAM_MSG_START], msg);
-	strcpy(&bytesToSend[DGRAM_PAYLOAD_START], payload);
+	memcpy(&bytesToSend[DGRAM_PAYLOAD_START], payload, lengthOfPayload);
 
-	int numBytesSend = send(sock, bytesToSend, DGRAM_MSG_LENGTH + DGRAM_NULL_LENGTH + strlen(payload), 0);
+	int numBytesSend = send(sock, bytesToSend, DGRAM_MSG_LENGTH + DGRAM_NULL_LENGTH + lengthOfPayload, 0);
 	if (numBytesSend >= 0) {
 		return numBytesSend;
 	} else {
@@ -41,9 +41,34 @@ int sendToXPlane(int sock, char *msg, char *payload) {
 	}
 }
 
-int connectXPlane(char *addr, int port) {
+int recvFromXPlane(int sock, char msg[DGRAM_MSG_LENGTH], void *payload, int maxLength) {
+	char buf[maxLength + DGRAM_MSG_LENGTH];
+	memset(buf, 0, sizeof(buf));
+	int recvBytes = recv(sock, buf, maxLength + DGRAM_MSG_LENGTH, 0);
+	if (recvBytes >= 0) {
+			printf("received (%d): ", recvBytes);
+			for (int i = 0; i < recvBytes; i++) {
+				printf("%02x ", buf[i]);
+			}
+			printf("\n");
+		if (recvBytes >= DGRAM_MSG_LENGTH) {
+			memcpy(msg, &buf[0], DGRAM_MSG_LENGTH);
+			memcpy(payload, &buf[DGRAM_MSG_LENGTH], maxLength);
+			return recvBytes - DGRAM_MSG_LENGTH;
+		} else {
+			fprintf(stderr, "Received data without message header?!");
+			return -11;
+		}
+	} else {
+		fprintf(stderr, "Error receiving data (%d): %s", errno, strerror(errno));
+		return -1;
+	}
+
+}
+
+int connectXPlane(char *destAddr, int destPort, int srcPort) {
 	int xPlaneSocket;
-	struct sockaddr_in6 xPlaneAddress;
+	struct sockaddr_in6 xPlaneAddress, localAddress;
 
 	int err;
 
@@ -54,15 +79,28 @@ int connectXPlane(char *addr, int port) {
 		return -1;
 	}
 
-	// prepare address struct
+	// prepare source address struct
+	localAddress.sin6_family = AF_INET6;
+	localAddress.sin6_port = htons(srcPort);
+	//inet_pton(AF_INET6, in6addr_any, &localAddress.sin6_addr.s6_addr);
+	localAddress.sin6_addr = in6addr_any;
+
+	// bind to local port
+	err = bind(xPlaneSocket, (struct sockaddr *)&localAddress, sizeof(localAddress));
+	if (err) {
+		fprintf(stderr, "Error binding [::]:%d (%d): %s\n", srcPort, errno, gai_strerror(errno));
+		return -1;
+	}
+
+	// prepare destination address struct
 	xPlaneAddress.sin6_family = AF_INET6;
-	xPlaneAddress.sin6_port = htons(PORT);
-	inet_pton(AF_INET6, SERVER, &xPlaneAddress.sin6_addr.s6_addr);
+	xPlaneAddress.sin6_port = htons(destPort);
+	inet_pton(AF_INET6, destAddr, &xPlaneAddress.sin6_addr.s6_addr);
 
 	// connect to xPlane
-	err = connect(xPlaneSocket, (struct sockaddr *)&xPlaneAddress, sizeof(xPlaneAddress));
+	//err = connect(xPlaneSocket, (struct sockaddr *)&xPlaneAddress, sizeof(xPlaneAddress));
 	if (err) {
-		fprintf(stderr, "Error connecting %s:%d (%d): %s\n", addr, port, err, gai_strerror(err));
+		fprintf(stderr, "Error connecting %s:%d (%d): %s\n", destAddr, destPort, errno, gai_strerror(errno));
 		return -1;
 	}
 

network.h

@@ -1,7 +1,9 @@
-#define SERVER "::1"
-#define PORT 49000
+#define DEST_SERVER "::1"
+#define DEST_PORT 49000
+#define SRC_PORT 49666
 
-#define SEND_BUFFER 256
+#define SEND_BUFFER 512
+#define RECV_BUFFER 256
 
 #define DGRAM_MSG_LENGTH 4
 #define DGRAM_NULL_LENGTH 1
@@ -9,6 +11,7 @@
 extern const int DGRAM_MSG_START;
 extern const int DGRAM_PAYLOAD_START;
 
-int sendToXPlane(int sock, char *msg, char *payload);
-int connectXPlane(char *addr, int port);
+int sendToXPlane(int sock, char *msg, void *payload, int lengthOfPayload);
+int recvFromXPlane(int sock, char msg[4], void *payload, int maxLength);
+int connectXPlane(char *destAddr, int destPort, int srcPort);
 int disconnectXPlane(int sock);