[Assignment-7] Flake + App base

- Add Assignment-7 to flake.nix
- Implement basic framework of app
- Implement proxy subcommand (mostly)
- Implement basics of intermediary subcommand

7-SGX_Hands-on/src/app/main.c

@@ -0,0 +1,24 @@
+#include <errno.h>
+#include <string.h>
+
+#include "intermediary.h"
+#include "proxy.h"
+#include "util.h"
+
+
+int main(int argc, char** argv) {
+    if(argc < 1)
+        syntax_exit();
+    BIN_NAME = argv[0];
+    if(argc < 2)
+        syntax_exit();
+
+    char* command = argv[1];
+
+    if(strcmp(command, "intermediary")==0)
+        handle_intermediary(argc-2, argv+2);
+    else if (strcmp(command, "proxy")==0)
+        handle_proxy(argc-2, argv+2);
+    else
+        syntax_exit();
+}