From 56bb116ab97281b53131b6b59f6924b109368c6b Mon Sep 17 00:00:00 2001
From: damage <damage@devloop.de>
Date: Sun, 21 Jan 2024 13:14:47 +0100
Subject: [PATCH] less magic numbers and generic send function

---
 command.c |  2 +-
 network.c | 36 ++++++++++++++++++------------------
 network.h | 11 ++++++++---
 3 files changed, 27 insertions(+), 22 deletions(-)

diff --git a/command.c b/command.c
index bb20b28..de35055 100644
--- a/command.c
+++ b/command.c
@@ -20,7 +20,7 @@ int main(int argc, char *argv[]) {
 	}
 
 	// send payload
-	if (sendCommand(xPlaneSocket, argv[1]) < 0) {
+	if (sendToXPlane(xPlaneSocket, "CMND", argv[1]) < 0) {
 		exit(EXIT_FAILURE);
 	}
 
diff --git a/network.c b/network.c
index 7f4d38e..0fdcff5 100644
--- a/network.c
+++ b/network.c
@@ -12,31 +12,31 @@
 
 #include "network.h"
 
-char* printable(char *str) {
-	char *ret = strdup(str);
+const int DGRAM_MSG_START = 0;
+const int DGRAM_PAYLOAD_START = DGRAM_MSG_START + DGRAM_MSG_LENGTH + DGRAM_NULL_LENGTH;
 
-	for (int i = strlen(ret); i >= 0; i--) {
-		if (ret[i] == '\r' || ret[i] == '\n') {
-			ret[i] = '\0';
-		}
+int sendToXPlane(int sock, char *msg, char *payload) {
+	char bytesToSend[SEND_BUFFER];
+	memset(bytesToSend, 0, SEND_BUFFER);
+
+	// msg is always 4 bytes long
+	if (strlen(msg) != DGRAM_MSG_LENGTH) {
+		return -10;
 	}
 
-	return ret;
-}
+	// payload shouldn't exceed buffer
+	if (strlen(payload) > (SEND_BUFFER - DGRAM_MSG_LENGTH - DGRAM_NULL_LENGTH)) {
+		return -11;
+	}
 
-int sendCommand(int sock, char *cmd) {
-	char bytesToSend[COMMAND_BUFFER];
-	memset(bytesToSend, 0, COMMAND_BUFFER);
+	strcpy(&bytesToSend[DGRAM_MSG_START], msg);
+	strcpy(&bytesToSend[DGRAM_PAYLOAD_START], payload);
 
-	strcpy(&bytesToSend[0], "CMND");
-	strcpy(&bytesToSend[5], cmd);
-
-	int numBytesSend = send(sock, bytesToSend, 5 + strlen(cmd), 0);
+	int numBytesSend = send(sock, bytesToSend, DGRAM_MSG_LENGTH + DGRAM_NULL_LENGTH + strlen(payload), 0);
 	if (numBytesSend >= 0) {
-		//printf("Send %d bytes to %s:%d: %s\n", numBytesSend, SERVER, PORT, printable(bytesToSend));
 		return numBytesSend;
 	} else {
-		fprintf(stderr, "Failed to send message to %s:%d (%d): %s", SERVER, PORT, errno, strerror(errno));
+		fprintf(stderr, "Failed to send message (%d): %s", errno, strerror(errno));
 		return -1;
 	}
 }
@@ -62,7 +62,7 @@ int connectXPlane(char *addr, int port) {
 	// connect to xPlane
 	err = connect(xPlaneSocket, (struct sockaddr *)&xPlaneAddress, sizeof(xPlaneAddress));
 	if (err) {
-		fprintf(stderr, "Error connecting %s:%d (%d): %s\n", SERVER, PORT, err, gai_strerror(err));
+		fprintf(stderr, "Error connecting %s:%d (%d): %s\n", addr, port, err, gai_strerror(err));
 		return -1;
 	}
 
diff --git a/network.h b/network.h
index 5b80f1f..5bb6047 100644
--- a/network.h
+++ b/network.h
@@ -1,9 +1,14 @@
 #define SERVER "::1"
 #define PORT 49000
 
-#define COMMAND_BUFFER 256
+#define SEND_BUFFER 256
 
-char* printable(char *str);
-int sendCommand(int sock, char *cmd);
+#define DGRAM_MSG_LENGTH 4
+#define DGRAM_NULL_LENGTH 1
+
+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 disconnectXPlane(int sock);