utils.cc

/***************************************************************************
 * utils.cc -- Various miscellaneous utility functions which defy          *
 * categorization :)                                                       *
 *                                                                         *
 ***********************IMPORTANT NMAP LICENSE TERMS************************
 *                                                                         *
 * The Nmap Security Scanner is (C) 1996-2017 Insecure.Com LLC ("The Nmap  *
 * Project"). Nmap is also a registered trademark of the Nmap Project.     *
 * This program is free software; you may redistribute and/or modify it    *
 * under the terms of the GNU General Public License as published by the   *
 * Free Software Foundation; Version 2 ("GPL"), BUT ONLY WITH ALL OF THE   *
 * CLARIFICATIONS AND EXCEPTIONS DESCRIBED HEREIN.  This guarantees your   *
 * right to use, modify, and redistribute this software under certain      *
 * conditions.  If you wish to embed Nmap technology into proprietary      *
 * software, we sell alternative licenses (contact sales@nmap.com).        *
 * Dozens of software vendors already license Nmap technology such as      *
 * host discovery, port scanning, OS detection, version detection, and     *
 * the Nmap Scripting Engine.                                              *
 *                                                                         *
 * Note that the GPL places important restrictions on "derivative works",  *
 * yet it does not provide a detailed definition of that term.  To avoid   *
 * misunderstandings, we interpret that term as broadly as copyright law   *
 * allows.  For example, we consider an application to constitute a        *
 * derivative work for the purpose of this license if it does any of the   *
 * following with any software or content covered by this license          *
 * ("Covered Software"):                                                   *
 *                                                                         *
 * o Integrates source code from Covered Software.                         *
 *                                                                         *
 * o Reads or includes copyrighted data files, such as Nmap's nmap-os-db   *
 * or nmap-service-probes.                                                 *
 *                                                                         *
 * o Is designed specifically to execute Covered Software and parse the    *
 * results (as opposed to typical shell or execution-menu apps, which will *
 * execute anything you tell them to).                                     *
 *                                                                         *
 * o Includes Covered Software in a proprietary executable installer.  The *
 * installers produced by InstallShield are an example of this.  Including *
 * Nmap with other software in compressed or archival form does not        *
 * trigger this provision, provided appropriate open source decompression  *
 * or de-archiving software is widely available for no charge.  For the    *
 * purposes of this license, an installer is considered to include Covered *
 * Software even if it actually retrieves a copy of Covered Software from  *
 * another source during runtime (such as by downloading it from the       *
 * Internet).                                                              *
 *                                                                         *
 * o Links (statically or dynamically) to a library which does any of the  *
 * above.                                                                  *
 *                                                                         *
 * o Executes a helper program, module, or script to do any of the above.  *
 *                                                                         *
 * This list is not exclusive, but is meant to clarify our interpretation  *
 * of derived works with some common examples.  Other people may interpret *
 * the plain GPL differently, so we consider this a special exception to   *
 * the GPL that we apply to Covered Software.  Works which meet any of     *
 * these conditions must conform to all of the terms of this license,      *
 * particularly including the GPL Section 3 requirements of providing      *
 * source code and allowing free redistribution of the work as a whole.    *
 *                                                                         *
 * As another special exception to the GPL terms, the Nmap Project grants  *
 * permission to link the code of this program with any version of the     *
 * OpenSSL library which is distributed under a license identical to that  *
 * listed in the included docs/licenses/OpenSSL.txt file, and distribute   *
 * linked combinations including the two.                                  *
 *                                                                         *
 * The Nmap Project has permission to redistribute Npcap, a packet         *
 * capturing driver and library for the Microsoft Windows platform.        *
 * Npcap is a separate work with it's own license rather than this Nmap    *
 * license.  Since the Npcap license does not permit redistribution        *
 * without special permission, our Nmap Windows binary packages which      *
 * contain Npcap may not be redistributed without special permission.      *
 *                                                                         *
 * Any redistribution of Covered Software, including any derived works,    *
 * must obey and carry forward all of the terms of this license, including *
 * obeying all GPL rules and restrictions.  For example, source code of    *
 * the whole work must be provided and free redistribution must be         *
 * allowed.  All GPL references to "this License", are to be treated as    *
 * including the terms and conditions of this license text as well.        *
 *                                                                         *
 * Because this license imposes special exceptions to the GPL, Covered     *
 * Work may not be combined (even as part of a larger work) with plain GPL *
 * software.  The terms, conditions, and exceptions of this license must   *
 * be included as well.  This license is incompatible with some other open *
 * source licenses as well.  In some cases we can relicense portions of    *
 * Nmap or grant special permissions to use it in other open source        *
 * software.  Please contact fyodor@nmap.org with any such requests.       *
 * Similarly, we don't incorporate incompatible open source software into  *
 * Covered Software without special permission from the copyright holders. *
 *                                                                         *
 * If you have any questions about the licensing restrictions on using     *
 * Nmap in other works, are happy to help.  As mentioned above, we also    *
 * offer alternative license to integrate Nmap into proprietary            *
 * applications and appliances.  These contracts have been sold to dozens  *
 * of software vendors, and generally include a perpetual license as well  *
 * as providing for priority support and updates.  They also fund the      *
 * continued development of Nmap.  Please email sales@nmap.com for further *
 * information.                                                            *
 *                                                                         *
 * If you have received a written license agreement or contract for        *
 * Covered Software stating terms other than these, you may choose to use  *
 * and redistribute Covered Software under those terms instead of these.   *
 *                                                                         *
 * Source is provided to this software because we believe users have a     *
 * right to know exactly what a program is going to do before they run it. *
 * This also allows you to audit the software for security holes.          *
 *                                                                         *
 * Source code also allows you to port Nmap to new platforms, fix bugs,    *
 * and add new features.  You are highly encouraged to send your changes   *
 * to the dev@nmap.org mailing list for possible incorporation into the    *
 * main distribution.  By sending these changes to Fyodor or one of the    *
 * Insecure.Org development mailing lists, or checking them into the Nmap  *
 * source code repository, it is understood (unless you specify            *
 * otherwise) that you are offering the Nmap Project the unlimited,        *
 * non-exclusive right to reuse, modify, and relicense the code.  Nmap     *
 * will always be available Open Source, but this is important because     *
 * the inability to relicense code has caused devastating problems for     *
 * other Free Software projects (such as KDE and NASM).  We also           *
 * occasionally relicense the code to third parties as discussed above.    *
 * If you wish to specify special license conditions of your               *
 * contributions, just say so when you send them.                          *
 *                                                                         *
 * This program is distributed in the hope that it will be useful, but     *
 * WITHOUT ANY WARRANTY; without even the implied warranty of              *
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the Nmap      *
 * license file for more details (it's in a COPYING file included with     *
 * Nmap, and also available from https://svn.nmap.org/nmap/COPYING)        *
 *                                                                         *
 ***************************************************************************/

/* $Id$ */

#include "nmap.h"
#include "utils.h"
#include "nmap_error.h"
#include "NmapOps.h"

#include <fcntl.h>
#include <errno.h>

extern NmapOps o;

/* Test a wildcard mask against a test string. Wildcard mask can include '*' and
   '?' which work the same as they do in /bin/sh (except it's case insensitive).
   Return val of 1 means it DID match. 0 means it DIDN'T. - Doug Hoyte, 2005 */
int wildtest(char *wild, char *test) {
  int i;

  while (*wild != '\0'  ||  *test != '\0') {
    if (*wild == '*') {
      /* --- Deal with multiple asterisks. --- */
      while (wild[1] == '*')
        wild++;

      /* --- Deal with terminating asterisks. --- */
      if (wild[1] == '\0')
        return 1;

      for (i = 0; test[i] != '\0'; i++) {
        if ((tolower((int) (unsigned char) wild[1]) == tolower((int) (unsigned char) test[i]) || wild[1] == '?')
            && wildtest(wild + 1, test + i) == 1) {
          return 1;
        }
      }

      return 0;
    }

    /* --- '?' can't match '\0'. --- */
    if (*wild == '?' && *test == '\0')
      return 0;

    if (*wild != '?' && tolower((int) (unsigned char) *wild) != tolower((int) (unsigned char) *test))
      return 0;
    wild++;
    test++;
  }

  return tolower((int) (unsigned char) *wild) == tolower((int) (unsigned char) *test);
}

/* Wrapper for nbase function hexdump. */
void nmap_hexdump(unsigned char *cp, unsigned int length) {
  char *string = NULL;

  string = hexdump((u8*) cp, length);
  if (string) {
    log_write(LOG_PLAIN, "%s", string);
    free(string);
  }

  return;
}


/* Like the perl equivalent, removes the terminating newline from string IF one
   exists. It then returns the POSSIBLY MODIFIED string. */
char *chomp(char *string) {
  int len = strlen(string);
  if (len && string[len - 1] == '\n') {
    if (len > 1 && string[len - 2] == '\r')
      string[len - 2] = '\0';
    else
      string[len - 1] = '\0';
  }
  return string;
}


/* Scramble the contents of an array. */
void genfry(unsigned char *arr, int elem_sz, int num_elem) {
  int i;
  unsigned int pos;
  unsigned char *bytes;
  unsigned char *cptr;
  unsigned short *sptr;
  unsigned int *iptr;
  unsigned char *tmp;
  int bpe;

  if (sizeof(unsigned char) != 1)
    fatal("%s() requires 1 byte chars", __func__);

  if (num_elem < 2)
    return;

  if (elem_sz == sizeof(unsigned short)) {
    shortfry((unsigned short *)arr, num_elem);
    return;
  }

  /* OK, so I am stingy with the random bytes! */
  if (num_elem < 256)
    bpe = sizeof(unsigned char);
  else if (num_elem < 65536)
    bpe = sizeof(unsigned short);
  else
    bpe = sizeof(unsigned int);

  bytes = (unsigned char *) safe_malloc(bpe * num_elem);
  tmp = (unsigned char *) safe_malloc(elem_sz);

  get_random_bytes(bytes, bpe * num_elem);
  cptr = bytes;
  sptr = (unsigned short *)bytes;
  iptr = (unsigned int *) bytes;

  for (i = num_elem - 1; i > 0; i--) {
    if (num_elem < 256) {
      pos = *cptr;
      cptr++;
    } else if (num_elem < 65536) {
      pos = *sptr;
      sptr++;
    } else {
      pos = *iptr;
      iptr++;
    }
    pos %= i + 1;
    if ((unsigned) i != pos) { /* memcpy is undefined when source and dest overlap. */
      memcpy(tmp, arr + elem_sz * i, elem_sz);
      memcpy(arr + elem_sz * i, arr + elem_sz * pos, elem_sz);
      memcpy(arr + elem_sz * pos, tmp, elem_sz);
    }
  }
  free(bytes);
  free(tmp);
}

void shortfry(unsigned short *arr, int num_elem) {
  int num;
  unsigned short tmp;
  int i;

  if (num_elem < 2)
    return;

  for (i = num_elem - 1; i > 0 ; i--) {
    num = get_random_ushort() % (i + 1);
    if (i == num)
      continue;
    tmp = arr[i];
    arr[i] = arr[num];
    arr[num] = tmp;
  }

  return;
}

/* Send data to a socket, keep retrying until an error or the full length is
   sent. Returns -1 if there is an error, or len if the full length was sent. */
int Send(int sd, const void *msg, size_t len, int flags) {
  int res;
  unsigned int sentlen = 0;

  do {
    res = send(sd, (char *) msg + sentlen, len - sentlen, flags);
    if (res > 0)
      sentlen += res;
  } while (sentlen < len && (res != -1 || socket_errno() == EINTR));

  return (res < 0) ? -1 : (int) len;
}

/* This function takes a command and the address of an uninitialized char **. It
   parses the command (by separating out whitespace) into an argv[]-style
   char **, which it sets the argv parameter to. The function returns the number
   of items filled up in the array (argc), or -1 in the case of an error. This
   function allocates memory for argv and thus it must be freed -- use
   argv_parse_free() for that. If arg_parse returns <1, then argv does not need
   to be freed. The returned arrays are always terminated with a NULL pointer */
int arg_parse(const char *command, char ***argv) {
  char **myargv = NULL;
  int argc = 0;
  char mycommand[4096];
  char *start, *end;
  char oldend;

  *argv = NULL;
  if (Strncpy(mycommand, command, 4096) == -1)
    return -1;
  myargv = (char **) safe_malloc((MAX_PARSE_ARGS + 2) * sizeof(char *));
  memset(myargv, 0, (MAX_PARSE_ARGS + 2) * sizeof(char *));
  myargv[0] = (char *) 0x123456; /* Integrity checker */
  myargv++;
  start = mycommand;
  while (start && *start) {
    while (*start && isspace((int) (unsigned char) *start))
      start++;
    if (*start == '"') {
      start++;
      end = strchr(start, '"');
    } else if (*start == '\'') {
      start++;
      end = strchr(start, '\'');
    } else if (!*start) {
      continue;
    } else {
      end = start + 1;
      while (*end && !isspace((int) (unsigned char) *end)) {
        end++;
      }
    }
    if (!end) {
      arg_parse_free(myargv);
      return -1;
    }
    if (argc >= MAX_PARSE_ARGS) {
      arg_parse_free(myargv);
      return -1;
    }
    oldend = *end;
    *end = '\0';
    myargv[argc++] = strdup(start);
    if (oldend)
      start = end + 1;
    else
      start = end;
  }
  myargv[argc + 1] = 0;
  *argv = myargv;

  return argc;
}

/* Free an argv allocated inside arg_parse */
void arg_parse_free(char **argv) {
  char **current;
  /* Integrity check */
  argv--;
  assert(argv[0] == (char *) 0x123456);
  current = argv + 1;
  while (*current) {
    free(*current);
    current++;
  }
  free(argv);
}

/* A simple function to form a character from 2 hex digits in ASCII form. */
static unsigned char hex2char(unsigned char a, unsigned char b) {
  int val;

  if (!isxdigit((int) a) || !isxdigit((int) b))
    return 0;
  a = tolower((int) a);
  b = tolower((int) b);
  if (isdigit((int) a))
    val = (a - '0') << 4;
  else
    val = (10 + (a - 'a')) << 4;

  if (isdigit((int) b))
    val += (b - '0');
  else
    val += 10 + (b - 'a');

  return (unsigned char) val;
}

/* Convert a string in the format of a roughly C-style string literal
   (e.g. can have \r, \n, \xHH escapes, etc.) into a binary string.
   This is done in-place, and the new (shorter or the same) length is
   stored in newlen.  If parsing fails, NULL is returned, otherwise
   str is returned. */
char *cstring_unescape(char *str, unsigned int *newlen) {
  char *dst = str, *src = str;
  char newchar;

  while (*src) {
    if (*src == '\\' ) {
      src++;
      switch (*src) {
      case '0':
        newchar = '\0';
        src++;
        break;
      case 'a': // Bell (BEL)
        newchar = '\a';
        src++;
        break;
      case 'b': // Backspace (BS)
        newchar = '\b';
        src++;
        break;
      case 'f': // Formfeed (FF)
        newchar = '\f';
        src++;
        break;
      case 'n': // Linefeed/Newline (LF)
        newchar = '\n';
        src++;
        break;
      case 'r': // Carriage Return (CR)
        newchar = '\r';
        src++;
        break;
      case 't': // Horizontal Tab (TAB)
        newchar = '\t';
        src++;
        break;
      case 'v': // Vertical Tab (VT)
        newchar = '\v';
        src++;
        break;
      case 'x':
        src++;
        if (!*src || !*(src + 1)) return NULL;
        if (!isxdigit((int) (unsigned char) *src) || !isxdigit((int) (unsigned char) * (src + 1))) return NULL;
        newchar = hex2char(*src, *(src + 1));
        src += 2;
        break;
      default:
        if (isalnum((int) (unsigned char) *src))
          return NULL; // I don't really feel like supporting octals such as \015
        // Other characters I'll just copy as is
        newchar = *src;
        src++;
        break;
      }
      *dst = newchar;
      dst++;
    } else {
      if (dst != src)
        *dst = *src;
      dst++;
      src++;
    }
  }
  *dst = '\0'; // terminated, but this string can include other \0, so use newlen
  if (newlen)
    *newlen = dst - str;

  return str;
}


void bintohexstr(char *buf, int buflen, char *src, int srclen) {
  int bp = 0;
  int i;

  for (i = 0; i < srclen; i++) {
    bp += Snprintf(buf + bp, buflen - bp, "\\x%02hhx", src[i]);
    if (bp >= buflen)
      break;
    if (i % 16 == 7) {
      bp += Snprintf(buf + bp, buflen - bp, " ");
      if (bp >= buflen)
        break;
    }
    if (i % 16 == 15) {
      bp += Snprintf(buf + bp, buflen - bp, "\n");
      if (bp >= buflen)
        break;
    }
  }
  if (i % 16 != 0 && bp < buflen)
    bp += Snprintf(buf + bp, buflen - bp, "\n");
}

/** Returns a buffer that contains the binary equivalent to the supplied
 *  hex spec or NULL in case of error.
 *  @warning Returned pointer points to a static buffer that subsequent calls
 *  will overwrite. */
u8 *parse_hex_string(char *str, size_t *outlen) {
  char auxbuff[4096];
  static u8 dst[16384];
  size_t dstlen=16384;
  unsigned int i=0, j=0;
  char *start=NULL;

  if(str==NULL || outlen==NULL)
    return NULL;
  /* This catches the empty string possibility "" */
  if(strlen(str) == 0)
    return NULL;
  else
    memset(auxbuff,0,4096);

  /* String should be treated as a hex number in this format: 0xAABBCCDDEE...
   * We process it the way it is specified, we don't perform byte order
   * conversions so if the users says 0x00AA we write dst[0]=0x00, dst[1]==0xAA
   * no matter the endianness of the host system. */
  if( !strncmp("0x", str, 2) ) {
    /* This catches the case of an empty "0x" */
    if(strlen(str) == 2)
      return NULL;
    start=str+2;
  }
  /* String should be treated as list of hex char in this format: \x00\xFF\x0A*/
  else if( !strncmp("\\x", str, 2) ) {
    /* This catches the case of an empty "\x" */
    if(strlen(str) == 2)
      return NULL;
    /* Copy all interesting bytes to an aux array, discard "\x" */
    for(i=0; i<strlen(str) && j<4095; i++) {
      if( str[i]!='\\' && str[i]!='x' && str[i]!='X')
        auxbuff[j++]=str[i];
    }
    auxbuff[j]='\0'; /* NULL terminate the string */
    start=auxbuff;
  }
  /* It must be a hex number in this format: AABBCCDDEE (without 0x or \x) */
  else {
    start=str;
  }

  /*OK, here we should have "start" pointing to the beginning of a string
   * in the format AABBCCDDEE... */
  /* Check if all we've got are hex chars */
  for(i=0; i<strlen(start); i++) {
    if( !isxdigit(start[i]) )
      return NULL;
  }
  /* Check if we have an even number of hex chars */
  if( strlen(start)%2 != 0 )
    return NULL;

  /* We are ready to parse this string */
  for(i=0, j=0; j<dstlen && i<strlen(start)-1; i+=2) {
    char twobytes[3];
    twobytes[0]=start[i];
    twobytes[1]=start[i+1];
    twobytes[2]='\0';
    dst[j++]=(u8)strtol(twobytes, NULL, 16);
  }
  /* Store final length */
  *outlen=j;
  return dst;
}

/* Get the CPE part (first component of the URL, should be "a", "h", or "o") as
   a character: 'a', 'h', or 'o'. Returns -1 on error. */
int cpe_get_part(const char *cpe) {
  const char *PREFIX = "cpe:/";
  char part;

  if (strncmp(cpe, PREFIX, strlen(PREFIX)) != 0)
    return -1;
  /* This could be more robust, by decoding character escapes and checking ':'
     boundaries. */
  part = cpe[strlen(PREFIX)];

  if (part == 'a' || part == 'h' || part == 'o')
    return part;
  else
    return -1;
}


#ifndef WIN32
static int open2mmap_flags(int open_flags)
{
  switch (open_flags) {
    case O_RDONLY: return PROT_READ;
    case O_RDWR:   return PROT_READ | PROT_WRITE;
    case O_WRONLY: return PROT_WRITE;
    default:
      return -1;
  }
}

/* mmap() an entire file into the address space. Returns a pointer to the
   beginning of the file. The mmap'ed length is returned inside the length
   parameter. If there is a problem, NULL is returned, the value of length is
   undefined, and errno is set to something appropriate. The user is responsible
   for doing an munmap(ptr, length) when finished with it. openflags should be
   O_RDONLY or O_RDWR, or O_WRONLY. */
char *mmapfile(char *fname, int *length, int openflags) {
  struct stat st;
  int fd;
  int mmap_flags;
  char *fileptr;

  if (!length || !fname) {
    errno = EINVAL;
    return NULL;
  }

  *length = -1;

  mmap_flags = open2mmap_flags(openflags);
  if (mmap_flags == -1) {
    errno = EINVAL;
    return NULL;
  }

  fd = open(fname, openflags);
  if (fd == -1) {
    return NULL;
  }

  if (fstat(fd, &st) == -1) {
    close(fd);
    return NULL;
  }

  fileptr = (char *)mmap(0, st.st_size, mmap_flags, MAP_SHARED, fd, 0);

  close(fd);

#ifdef MAP_FAILED
  if (fileptr == (void *)MAP_FAILED) return NULL;
#else
  if (fileptr == (char *) - 1) return NULL;
#endif

  *length = st.st_size;
  return fileptr;
}
#else /* WIN32 */
/* FIXME:  From the looks of it, this function can only handle one mmaped file
   at a time (note how gmap is used). */
/* I believe this was written by Ryan Permeh (ryan@eeye.com). */

static HANDLE gmap = NULL;

char *mmapfile(char *fname, int *length, int openflags) {
  HANDLE fd;
  DWORD mflags, oflags;
  char *fileptr;

  if (!length || !fname) {
    WSASetLastError(EINVAL);
    return NULL;
  }

  if (openflags == O_RDONLY) {
    oflags = GENERIC_READ;
    mflags = PAGE_READONLY;
  } else {
    oflags = GENERIC_READ | GENERIC_WRITE;
    mflags = PAGE_READWRITE;
  }

  fd = CreateFile(
         fname,
         oflags,                       // open flags
         0,                            // do not share
         NULL,                         // no security
         OPEN_EXISTING,                // open existing
         FILE_ATTRIBUTE_NORMAL,
         NULL);                        // no attr. template
  if (!fd)
    pfatal ("%s(%u): CreateFile()", __FILE__, __LINE__);

  *length = (int) GetFileSize (fd, NULL);

  gmap = CreateFileMapping (fd, NULL, mflags, 0, 0, NULL);
  if (!gmap) {
    pfatal("%s(%u): CreateFileMapping(), file '%s', length %d, mflags %08lX",
           __FILE__, __LINE__, fname, *length, mflags);
  }

  fileptr = (char*) MapViewOfFile (gmap, oflags == GENERIC_READ ? FILE_MAP_READ : FILE_MAP_WRITE, 0, 0, 0);
  if (!fileptr)
    pfatal ("%s(%u): MapViewOfFile()", __FILE__, __LINE__);

  if (o.debugging > 2) {
    log_write(LOG_PLAIN, "%s(): fd %08lX, gmap %08lX, fileptr %08lX, length %d\n",
              __func__, (DWORD)fd, (DWORD)gmap, (DWORD)fileptr, *length);
  }

  CloseHandle (fd);

  return fileptr;
}


/* FIXME:  This only works if the file was mapped by mmapfile (and only
   works if the file is the most recently mapped one */
int win32_munmap(char *filestr, int filelen) {
  if (gmap == 0)
    fatal("%s: no current mapping !\n", __func__);
  FlushViewOfFile(filestr, filelen);
  UnmapViewOfFile(filestr);
  CloseHandle(gmap);
  gmap = NULL;
  return 0;
}
#endif