added english source and (old) german exe

manipulate_hosts.c

@@ -0,0 +1,112 @@
+/*
+ * manipulate_hosts.c
+ *
+ * author: Patrick Neumann
+ * version: 1.0 (02.11.2010)
+ *
+ * compile under (with):
+ * - linux (http://gcc.gnu.org/)
+ * - windows (http://www.mingw.org/)
+ * - mac os x (work-in-progress)
+ *
+ * quick start guide:
+ * 1. ping "www.microsoft.com" before
+ * 2. run program
+ * 3. ping "www.microsoft.com" afterwards
+ * 4. compare outputs
+ * 5. execute the program again
+ * 6. now everything should be the same as before
+ *
+ * HINT: is not working on windows anymore because
+ *         the anti virus tools from today detect that kind of modification!
+ *
+ */
+
+#include <stdlib.h>
+#include <stdio.h>
+#include <string.h> // needed for the functions "strcpy", "strcat" und "strstr"
+#define LINELENGTH 80
+#ifdef __unix__
+  #include <unistd.h> // needed for the function "access"
+  #define WRITE W_OK
+#else
+  #include <io.h> // needed for the function "access"
+  #define WRITE 02
+#endif
+
+int main(void) {
+  #ifdef __unix__
+    char oldfile[50] = "/etc/";
+  #else
+    char oldfile[50] = "C:\\WINDOWS\\system32\\drivers\\etc\\";
+  #endif
+  char newfile[50];
+  strcpy( newfile, oldfile );
+  strcat( oldfile, "hosts" );
+  strcat( newfile, "newhosts" );
+  char newline[50] = "149.20.20.133 www.microsoft.com";
+  FILE *quelle, *ziel;
+  char puffer[ LINELENGTH ];
+  int counter = 0;
+
+  // check if the source could be opened and be written (for the later "delete before rename")
+  if( access( oldfile, WRITE ) == -1 ) {
+    fprintf( stderr, "Will not be able to delete %s later.\n", oldfile );
+    return EXIT_FAILURE;
+  }
+
+  // open source
+  if( ( quelle=fopen( oldfile, "r" ) ) == NULL ) {
+    fprintf( stderr, "Can not open %s.\n", oldfile );
+    return EXIT_FAILURE;
+  }
+
+  // open target
+  if( ( ziel=fopen( newfile, "w" ) ) == NULL ) {
+    fprintf( stderr, "Can not open %s.\n", newfile );
+    return EXIT_FAILURE;
+  }
+
+  while( fgets( puffer, LINELENGTH, quelle ) ) {
+    // if text is not found, then ...
+    if( strstr( puffer, newline ) == 0 ) {
+       fputs( puffer, ziel );
+    }
+    // if text is found, then ...
+    else {
+      counter++;
+    }
+  }
+
+  // if counter unchanged, then ...
+  if( counter == 0 ) {
+    fputs( newline, ziel );
+    fputs( "\n", ziel );
+    printf( "The line \"%s\" was added to %s.\n", newline, oldfile );
+  }
+  else {
+    printf( "The line \"%s\" has been removed from %s.\n", newline, oldfile );
+  }
+
+  // close both files before deleting / renaming
+  fclose(quelle);
+  fclose(ziel);
+
+  // delete original
+  if( ( remove( oldfile ) ) == -1 ) {
+    fprintf( stderr, "Error while deleting %s.\n", oldfile );
+    return EXIT_FAILURE;
+  }
+
+  // rename manupulated copy to original
+  if( ( rename( newfile, oldfile ) ) == -1 ) {
+    fprintf( stderr, "Error while renaming %s.\n", newfile );
+    return EXIT_FAILURE;
+  }
+
+  // so that the console esp. under windows does not disappear with "speed of light" again ...
+  printf( "EXIT WITH RETURN..." );
+  getchar();
+
+  return EXIT_SUCCESS;
+}