update

2020-09-29 00:41:15 -04:00
parent 651fae06c2
commit eaa86d6d8f
4 changed files with 133 additions and 0 deletions
@@ -0,0 +1,13 @@
+CC=gcc
+CFLAGS= -z execstack -fno-stack-protector -g
+
+all: is_valid_html product_register
+
+is_valid_html: is_valid_html.c
+	$(CC) -o is_valid_html is_valid_html.c $(CFLAGS)
+
+product_register: product_register.c
+	$(CC) -o product_register product_register.c $(CFLAGS)
+
+clean:
+	rm is_valid_html product_register
@@ -0,0 +1,63 @@
+/* 
+  Hassan Khan <hassan.khan@uoguelph.ca>
+  University of Guelph
+  Buffer Overflow Lab
+
+  Program that verifies that the argument is a valid html file
+
+*/ 
+  
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+int verify_signature(char *buffer) {
+  char VALID_SIGNATURE[24] = "<!DOCTYPE HTML PUBLIC";
+  return strncmp(VALID_SIGNATURE, buffer, strlen(VALID_SIGNATURE));
+}
+
+int verify_extension(char* fname) {
+  char extension[4];
+  char* ptr_fname = fname;
+  while (*ptr_fname) {
+    if (*ptr_fname++ == '.') {
+      strcpy(extension, ptr_fname);
+      break;
+    }
+  }
+  return strcmp("html", extension);
+}
+ 
+int main(int argc, char ** argv) {
+  char buffer[256];
+  FILE *file = NULL;
+  int rv = 0;
+
+  //verify the number of arguments
+  if (argc < 2) {
+    printf("Usage: %s <file-to-test>\n", argv[0]);
+    return 0;
+  }
+  rv = verify_extension(argv[1]);
+  if (rv != 0) {
+    printf("Invalid html\n");
+    return 0;
+  }
+  //read file
+  if ((file = fopen(argv[1], "r")) == NULL) {
+    printf("File read error\n");
+    return 0;
+  }
+  fscanf(file,"%[^\n]", buffer);
+  fclose(file);
+
+  rv = verify_signature(buffer);
+  if (rv != 0) {
+    printf("Invalid html\n");
+    return 0;
+  }
+
+  printf("Valid html\n");
+  return 1;
+   
+}   
@@ -0,0 +1,47 @@
+/*
+  Hassan Khan <hassan.khan@uoguelph.ca>
+  CIS*6540: Buffer Overflow Lab
+*/
+#include <stdio.h>
+#include <string.h>
+
+#define BUF_LEN 32
+
+int match_prod_key(char* key) {
+  char usr_key[BUF_LEN];
+  char rv = 0;
+  char saved_key[BUF_LEN] = "123456"; //TODO: store in a secure DB
+  int cmp = 0;
+  strcpy(usr_key, key);
+  char* ptr_usr_key = usr_key;
+  char* ptr_saved_key = saved_key;
+  
+  for (; *ptr_usr_key || *ptr_saved_key;) 
+    cmp += (*ptr_usr_key++) - (*ptr_saved_key++);
+  
+  if (cmp == 0)
+    return !rv;
+  else
+    return rv;
+}
+
+int main(int argc, char **argv) {
+  char rv = 0;
+  char local_buf[BUF_LEN];
+ 
+  if (argc != 2) {
+    printf("Usage: %s <product-key>\n", argv[0]);
+    return 0;
+  }
+  //Prevent nefarious buffer overflow by limiting to prod key and a null term
+  strncpy(local_buf, argv[1], BUF_LEN + 1);
+  rv = match_prod_key(local_buf);
+
+  if (rv == 1) 
+    printf("Product Key Accepted!!!\n");
+  else
+    printf("Invalid Product Key\n");
+
+  return rv;
+}
+
@@ -0,0 +1,10 @@
+<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN"
+   "http://www.w3.org/TR/html4/strict.dtd">
+<HTML>
+   <HEAD>
+      <TITLE>My test HTML document</TITLE>
+   </HEAD>
+   <BODY>
+      <P>Hello world!
+   </BODY>
+</HTML>