added options input

1 files changed, 47 insertions, 9 deletions

diff --git a/keygen.c b/keygen.c
index 4d7d4dd..0dd64ca 100644
--- a/keygen.c
+++ b/keygen.c
@@ -1,14 +1,52 @@
 #include<stdio.h>
 #include<openssl/rand.h>
+#include<unistd.h>
 
 int main(int argc, char* argv[]) {
-	long long int len = strtoll(argv[1], NULL, 10);
-	unsigned char key[len];
-	RAND_bytes(key, len);
-	FILE* file = fopen(argv[2], "w");
-	fwrite(key, len, 1, file);
-	fclose(file);
-	printf("Created key file %s of %lli bytes \n", argv[2], len);
-
-	return 0;
+
+        int opt;
+	int nbytes = 256;
+        char* output;
+	int defout = 0;
+	int defbyte = 0;
+        while ((opt = getopt(argc, argv, "b:o:")) != -1) {
+                switch (opt) {
+                case 'b':
+                        nbytes = atoi(optarg);
+			defbyte = 1;
+                        break;
+                case 'o':
+                        output = argv[(optind-1)];
+			defout = 1;
+                        break;
+                default:
+                        fprintf(stderr, "Usage: %s [-b nbytes] [-o output] \n", argv[0]);
+                        exit(EXIT_FAILURE);
+                }
+        }
+
+	if (nbytes < 0) {
+		printf("Negative byte value inserted! \n");
+		printf("Exiting... \n");
+		exit(EXIT_FAILURE);
+	} else if (nbytes != 0) {
+		if (defbyte == 0) {
+			printf("No byte number specified... using default value: 256 \n");
+		}
+		unsigned char key[nbytes];
+		RAND_bytes(key, nbytes);
+		if (defout == 0) {
+			output = "default.key";
+			printf("No output name specified... using default value: default.key \n");
+		}
+		FILE* file = fopen(output, "w");
+		fwrite(key, nbytes, 1, file);
+		fclose(file);
+		printf("Created key file %s of %d bytes \n", output, nbytes);
+	} else {
+		printf("Byte number specified is 0. \n");
+		printf("Doing nothing! \n");
+	}
+
+	exit(EXIT_SUCCESS);
 }