Initial client implementation

firewall-server/client.c

@@ -1,6 +1,73 @@
+#include <stdlib.h>
 #include <stdio.h>
+#include <string.h>
+
+#define USAGE "usage: %s IP PORT OPCODE [ARGS...]\n"
 
 int main (int argc, char **argv) {
-    // Client to be written
+    if (argc < 4) {
+        fprintf(stderr, USAGE, argv[0]);
+        return 1;
+    }
+
+    const char *ip = argv[1];
+    const char *port = argv[2];
+    const char *opcode = argv[3];
+
+    if (strlen(opcode) != 1) {
+        fprintf(stderr, "invalid opcode\n");
+        return 1;
+    }
+
+    char *payload = NULL;
+
+    switch (opcode[0]) {
+        case 'A':
+        case 'D':
+        case 'C': {
+            if (argc < 6) {
+                fprintf(stderr, USAGE, argv[0]);
+                fprintf(stderr, "not enough arguments for opcode %s\n", opcode);
+                return 1;
+            }
+
+            int payload_len = strlen(ip) + strlen(port) + 1;
+            payload = (char *) malloc(sizeof(char) * (payload_len + 1));
+            memset(payload, 0, payload_len + 1);
+
+            strcat(payload, argv[4]);
+
+            if (opcode[0] == 'C') {
+                strcat(payload, ",");
+            } else {
+                strcat(payload, " ");
+            }
+
+            strcat(payload, argv[5]);
+        }
+        case 'L': {
+            break;
+        }
+        default: {
+            fprintf(stderr, "invalid opcode\n");
+            return 1;
+        }
+    }
+
+    unsigned char payload_size = 0;
+    if (payload != NULL) {
+        payload_size = strlen(payload);
+    }
+
+    char *message = (char *)malloc(sizeof(char) * (payload_size + 3));
+    message[0] = opcode[0];
+    message[1] = payload_size;
+    if (payload != NULL) {
+        strcat(message + 2, payload);
+        free(payload);
+    }
+
+    fwrite(message, 1, 2 + payload_size, stdout);
+
     return 0;
 }