From 4e0036e5f9632c046c2bb0a797f28ada87c43642 Mon Sep 17 00:00:00 2001
From: Fredrik Robertsen <fredrikr79@pm.me>
Date: Sat, 7 Feb 2026 22:16:10 +0100
Subject: [PATCH] rcon protocol helpers

---
 src/main.c | 100 ++++++++++++++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 99 insertions(+), 1 deletion(-)

diff --git a/src/main.c b/src/main.c
index 6d2ec3d..930fba8 100644
--- a/src/main.c
+++ b/src/main.c
@@ -58,9 +58,107 @@ int rcon_connect(int port) {
     return sockfd;
 }
 
+
+void send_packet(int sockfd, int32_t id, int32_t type, const char *body) {
+    int body_len = strlen(body);
+    int32_t size = 10 + body_len; // 4 (id) + 4 (type) + body + 2 (null terminators)
+
+    send(sockfd, &size, sizeof(int32_t), 0);
+    send(sockfd, &id, sizeof(int32_t), 0);
+    send(sockfd, &type, sizeof(int32_t), 0);
+    send(sockfd, body, body_len + 1, 0);
+    const char null = '\0';
+    send(sockfd, &null, 1, 0);
+}
+
+int recv_packet(int sockfd, rcon_packet_t *packet) {
+    if (recv(sockfd, &packet->size, sizeof(int32_t), 0) <= 0) { return -1; }
+    if (recv(sockfd, &packet->id, sizeof(int32_t), 0) <= 0) { return -1; }
+    if (recv(sockfd, &packet->type, sizeof(int32_t), 0) <= 0) { return -1; }
+
+    // read body (size - 10 bytes for id, type, and two null terminators)
+    int body_size = packet->size - 10;
+    if (body_size > 0 && body_size < sizeof(packet->body)) {
+        if (recv(sockfd, packet->body, body_size + 2, 0) <= 0) {
+            return -1;
+        }
+        packet->body[body_size] = '\0';
+    } else {
+        packet->body[0] = '\0';
+    }
+
+    return 0;
+}
+
+int rcon_authenticate(int sockfd, const char *password) {
+    send_packet(sockfd, 1, SERVERDATA_AUTH, password);
+
+    rcon_packet_t response;
+    if (recv_packet(sockfd, &response) < 0) {
+        perror("failed to receive auth response\n");
+        return -1;
+    }
+
+    if (response.id == -1) {
+        perror("authentication failed\n");
+        return -1;
+    }
+
+    printf("authenticated successfully\n");
+    return 0;
+}
+
+char* rcon_command(int sockfd, const char *command) {
+    static char result[8192];
+    result[0] = '\0';
+
+    send_packet(sockfd, 2, SERVERDATA_EXECCOMMAND, command);
+
+    // Handle multi-packet responses
+    while (1) {
+        rcon_packet_t response;
+        if (recv_packet(sockfd, &response) < 0) {
+            perror("failed to receive command response\n");
+            return NULL;
+        }
+
+        if (response.type == SERVERDATA_RESPONSE_VALUE) {
+            strncat(result, response.body, sizeof(result) - strlen(result) - 1);
+
+            // Check if response is complete (body length < 4096)
+            if (strlen(response.body) < 4096) {
+                break;
+            }
+        }
+    }
+
+    return result;
+}
+
 int main(int argc, char **argv) {
     const int PORT_NUM = read_env_int("RCON_PORT_NUMBER");
+    const char *password = getenv("RCON_PASSWORD");
+
+    if (password == NULL) {
+        perror("error: RCON_PASSWORD environment variable not set.\n");
+        exit(EXIT_FAILURE);
+    }
+
     printf("port: %d\n", PORT_NUM);
 
-    rcon_connect(PORT_NUM);
+    int sockfd = rcon_connect(PORT_NUM);
+
+    if (rcon_authenticate(sockfd, password) < 0) {
+        close(sockfd);
+        exit(EXIT_FAILURE);
+    }
+
+    // example
+    char *response = rcon_command(sockfd, "help");
+    if (response) {
+        printf("Response:\n%s\n", response);
+    }
+
+    close(sockfd);
+    return 0;
 }