first draft

utils/Makefile

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+CC=gcc
+CCOPT=-Wall
+
+all: hex2bin
+
+hex2bin: hex2bin.c
+	$(CC) $(CCOPT) -o hex2bin hex2bin.c
+
+clean:
+	rm -f hex2bin

utils/README.HEX2BIN

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+hex2bin is an utility to convert a string in hexadecimal format like
+"2b2b2b415448300d" (an example to test a stupid modem vulnerability)
+in the binary equivalent. For example:
+
+# echo -n "2b2b2b415448300d" | ./hex2bin > modem.string
+
+# cat modem.string
++++ATH0
+
+# ls -l modem.string
+-rw-r--r--   1 antirez  users           8 Nov 17 16:01 modem.string
+
+# hping2 --file ./modem.string -d 8 --icmp target.host.org
+
+using switch '-r' hex2bin perform exactly the inverse operation.
+for example:
+
+echo "antirez" | ./hex2bin -r
+
+616e746972657a0a

utils/hex2bin.c

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+/*
+ * hex2bin - simple hex to bin filter
+ * antirez@invece.org - under GPL version 2
+ */
+
+#include <stdio.h>
+#include <sys/stat.h>
+#include <sys/types.h>
+#include <fcntl.h>
+#include <unistd.h>
+#include <string.h>
+
+int hex2bin(void)
+{
+	char hex[3];
+	int d = 0;
+	unsigned char c;
+	int stdin_fd = fileno(stdin);
+	int n_read;
+
+	while((n_read = read(stdin_fd, hex, 2)) > 0)
+	{
+		if (n_read == 1)
+		{
+			if (hex[0] != '\n')
+			{
+				fprintf(stderr,
+				"input parse error, odd digits in hex file\n");
+				exit(1);
+			}
+			else
+				exit(1);
+		}
+		hex[2] = '\0';
+		sscanf(hex, "%x", &d);
+		c = (unsigned char) d;
+		printf("%c", c);
+	}
+	return 0;
+}
+
+int bin2hex(void)
+{
+	int stdin_fd = fileno(stdin);
+	int n_read;
+	unsigned char c;
+
+	while((n_read = read(stdin_fd, &c, 1)) > 0)
+	{
+		printf("%.2x", c);
+	}
+	return 0;
+}
+
+int main(int argc, char **argv)
+{
+	if (argc >= 2 && strstr(argv[1], "-r"))
+		bin2hex();
+	else
+		hex2bin();
+
+	return 0;
+}