formdata.c

/***************************************************************************
 *                                  _   _ ____  _     
 *  Project                     ___| | | |  _ \| |    
 *                             / __| | | | |_) | |    
 *                            | (__| |_| |  _ <| |___ 
 *                             \___|\___/|_| \_\_____|
 *
 * Copyright (C) 1998 - 2004, Daniel Stenberg, <daniel@haxx.se>, et al.
 *
 * This software is licensed as described in the file COPYING, which
 * you should have received as part of this distribution. The terms
 * are also available at http://curl.haxx.se/docs/copyright.html.
 * 
 * You may opt to use, copy, modify, merge, publish, distribute and/or sell
 * copies of the Software, and permit persons to whom the Software is
 * furnished to do so, under the terms of the COPYING file.
 *
 * This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
 * KIND, either express or implied.
 *
 * $Id$
 ***************************************************************************/

/*
  Debug the form generator stand-alone by compiling this source file with:

  gcc -DHAVE_CONFIG_H -I../ -g -D_FORM_DEBUG -o formdata -I../include formdata.c strequal.c

  run the 'formdata' executable the output should end with:
  All Tests seem to have worked ...
  and the following parts should be there:

Content-Disposition: form-data; name="simple_COPYCONTENTS"
value for simple COPYCONTENTS

Content-Disposition: form-data; name="COPYCONTENTS_+_CONTENTTYPE"
Content-Type: image/gif
value for COPYCONTENTS + CONTENTTYPE

Content-Disposition: form-data; name="PRNAME_+_NAMELENGTH_+_COPYNAME_+_CONTENTSLENGTH"
vlue for PTRNAME + NAMELENGTH + COPYNAME + CONTENTSLENGTH
(or you might see P^@RNAME and v^@lue at the start)

Content-Disposition: form-data; name="simple_PTRCONTENTS"
value for simple PTRCONTENTS

Content-Disposition: form-data; name="PTRCONTENTS_+_CONTENTSLENGTH"
vlue for PTRCONTENTS + CONTENTSLENGTH
(or you might see v^@lue at the start)

Content-Disposition: form-data; name="PTRCONTENTS_+_CONTENTSLENGTH_+_CONTENTTYPE"
Content-Type: text/plain
vlue for PTRCOTNENTS + CONTENTSLENGTH + CONTENTTYPE
(or you might see v^@lue at the start)

Content-Disposition: form-data; name="FILE1_+_CONTENTTYPE"; filename="inet_ntoa_r.h"
Content-Type: text/html
...

Content-Disposition: form-data; name="FILE1_+_FILE2"
Content-Type: multipart/mixed, boundary=curlz1s0dkticx49MV1KGcYP5cvfSsz
...
Content-Disposition: attachment; filename="inet_ntoa_r.h"
Content-Type: text/plain
...
Content-Disposition: attachment; filename="Makefile.b32.resp"
Content-Type: text/plain
...

Content-Disposition: form-data; name="FILE1_+_FILE2_+_FILE3"
Content-Type: multipart/mixed, boundary=curlirkYPmPwu6FrJ1vJ1u1BmtIufh1
...
Content-Disposition: attachment; filename="inet_ntoa_r.h"
Content-Type: text/plain
...
Content-Disposition: attachment; filename="Makefile.b32.resp"
Content-Type: text/plain
...
Content-Disposition: attachment; filename="inet_ntoa_r.h"
Content-Type: text/plain
...


Content-Disposition: form-data; name="ARRAY: FILE1_+_FILE2_+_FILE3"
Content-Type: multipart/mixed, boundary=curlirkYPmPwu6FrJ1vJ1u1BmtIufh1
...
Content-Disposition: attachment; filename="inet_ntoa_r.h"
Content-Type: text/plain
...
Content-Disposition: attachment; filename="Makefile.b32.resp"
Content-Type: text/plain
...
Content-Disposition: attachment; filename="inet_ntoa_r.h"
Content-Type: text/plain
...

Content-Disposition: form-data; name="FILECONTENT"
...

 */

#include "setup.h"

#ifndef CURL_DISABLE_HTTP

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <stdarg.h>

#include <time.h>

#include <curl/curl.h>
#include "formdata.h"

#include "strequal.h"

/* The last #include file should be: */
#ifdef CURLDEBUG
#include "memdebug.h"
#endif

/* Length of the random boundary string. */
#define BOUNDARY_LENGTH 40

/* What kind of Content-Type to use on un-specified files with unrecognized
   extensions. */
#define HTTPPOST_CONTENTTYPE_DEFAULT "application/octet-stream"

/* This is a silly duplicate of the function in main.c to enable this source
   to compile stand-alone for better debugging */
static void GetStr(char **string,
		   const char *value)
{
  if(*string)
    free(*string);
  *string = strdup(value);
}

/***************************************************************************
 *
 * FormParse()
 *	
 * Reads a 'name=value' paramter and builds the appropriate linked list.
 *
 * Specify files to upload with 'name=@filename'. Supports specified
 * given Content-Type of the files. Such as ';type=<content-type>'.
 *
 * You may specify more than one file for a single name (field). Specify
 * multiple files by writing it like:
 *
 * 'name=@filename,filename2,filename3'
 *
 * If you want content-types specified for each too, write them like:
 *
 * 'name=@filename;type=image/gif,filename2,filename3'
 *
 ***************************************************************************/

#define FORM_FILE_SEPARATOR ','
#define FORM_TYPE_SEPARATOR ';'

/***************************************************************************
 *
 * AddHttpPost()
 *	
 * Adds a HttpPost structure to the list, if parent_post is given becomes
 * a subpost of parent_post instead of a direct list element.
 *
 * Returns newly allocated HttpPost on success and NULL if malloc failed.
 *
 ***************************************************************************/
static struct curl_httppost *
AddHttpPost(char * name, size_t namelength,
            char * value, size_t contentslength,
            char * buffer, size_t bufferlength,
            char *contenttype,
            long flags,
            struct curl_slist* contentHeader,
            char *showfilename,
            struct curl_httppost *parent_post,
            struct curl_httppost **httppost,
            struct curl_httppost **last_post)
{
  struct curl_httppost *post;
  post = (struct curl_httppost *)malloc(sizeof(struct curl_httppost));
  if(post) {
    memset(post, 0, sizeof(struct curl_httppost));
    post->name = name;
    post->namelength = (long)(name?(namelength?namelength:strlen(name)):0);
    post->contents = value;
    post->contentslength = (long)contentslength;
    post->buffer = buffer;
    post->bufferlength = (long)bufferlength;
    post->contenttype = contenttype;
    post->contentheader = contentHeader;
    post->showfilename = showfilename;
    post->flags = flags;
  }
  else
    return NULL;
  
  if (parent_post) {
    /* now, point our 'more' to the original 'more' */
    post->more = parent_post->more;
    
    /* then move the original 'more' to point to ourselves */
    parent_post->more = post;	         
  }
  else {
    /* make the previous point to this */
    if(*last_post)
      (*last_post)->next = post;
    else
      (*httppost) = post;
    
    (*last_post) = post;  
  }
  return post;
}

/***************************************************************************
 *
 * AddFormInfo()
 *	
 * Adds a FormInfo structure to the list presented by parent_form_info.
 *
 * Returns newly allocated FormInfo on success and NULL if malloc failed/
 * parent_form_info is NULL.
 *
 ***************************************************************************/
static FormInfo * AddFormInfo(char *value,
                              char *contenttype,
                              FormInfo *parent_form_info)
{
  FormInfo *form_info;
  form_info = (FormInfo *)malloc(sizeof(FormInfo));
  if(form_info) {
    memset(form_info, 0, sizeof(FormInfo));
    if (value)
      form_info->value = value;
    if (contenttype)
      form_info->contenttype = contenttype;
    form_info->flags = HTTPPOST_FILENAME;
  }
  else
    return NULL;
  
  if (parent_form_info) {
    /* now, point our 'more' to the original 'more' */
    form_info->more = parent_form_info->more;
    
    /* then move the original 'more' to point to ourselves */
    parent_form_info->more = form_info;
  }
  else
    return NULL;

  return form_info;
}

/***************************************************************************
 *
 * ContentTypeForFilename()
 *	
 * Provides content type for filename if one of the known types (else
 * (either the prevtype or the default is returned).
 *
 * Returns some valid contenttype for filename.
 *
 ***************************************************************************/
static const char * ContentTypeForFilename (const char *filename,
					    const char *prevtype)
{
  const char *contenttype = NULL;
  unsigned int i;
  /*
   * No type was specified, we scan through a few well-known
   * extensions and pick the first we match!
   */
  struct ContentType {
    const char *extension;
    const char *type;
  };
  static struct ContentType ctts[]={
    {".gif",  "image/gif"},
    {".jpg",  "image/jpeg"},
    {".jpeg", "image/jpeg"},
    {".txt",  "text/plain"},
    {".html", "text/html"}
  };
  
  if(prevtype)
    /* default to the previously set/used! */
    contenttype = prevtype;
  else
    /* It seems RFC1867 defines no Content-Type to default to
       text/plain so we don't actually need to set this: */
    contenttype = HTTPPOST_CONTENTTYPE_DEFAULT;
  
  for(i=0; i<sizeof(ctts)/sizeof(ctts[0]); i++) {
    if(strlen(filename) >= strlen(ctts[i].extension)) {
      if(strequal(filename +
		  strlen(filename) - strlen(ctts[i].extension),
		  ctts[i].extension)) {
	contenttype = ctts[i].type;
	break;
      }	      
    }
  }
  /* we have a contenttype by now */
  return contenttype;
}

/***************************************************************************
 *
 * AllocAndCopy()
 *	
 * Copies the data currently available under *buffer using newly allocated
 * buffer (that becomes *buffer). Uses buffer_length if not null, else
 * uses strlen to determine the length of the buffer to be copied
 *
 * Returns 0 on success and 1 if the malloc failed.
 *
 ***************************************************************************/
static int AllocAndCopy(char **buffer, size_t buffer_length)
{
  const char *src = *buffer;
  size_t length;
  bool add = FALSE;
  if (buffer_length)
    length = buffer_length;
  else {
    length = strlen(*buffer);
    add = TRUE;
  }
  *buffer = (char*)malloc(length+add);
  if (!*buffer)
    return 1;
  memcpy(*buffer, src, length);
  /* if length unknown do null termination */
  if (add)
    (*buffer)[length] = '\0';
  return 0;
}

/***************************************************************************
 *
 * FormAdd()
 *	
 * Stores a 'name=value' formpost parameter and builds the appropriate
 * linked list.
 *
 * Has two principal functionalities: using files and byte arrays as
 * post parts. Byte arrays are either copied or just the pointer is stored
 * (as the user requests) while for files only the filename and not the
 * content is stored.
 *
 * While you may have only one byte array for each name, multiple filenames
 * are allowed (and because of this feature CURLFORM_END is needed after
 * using CURLFORM_FILE).
 *
 * Examples:
 *
 * Simple name/value pair with copied contents:
 * curl_formadd (&post, &last, CURLFORM_COPYNAME, "name",
 * CURLFORM_COPYCONTENTS, "value", CURLFORM_END);
 *
 * name/value pair where only the content pointer is remembered:
 * curl_formadd (&post, &last, CURLFORM_COPYNAME, "name",
 * CURLFORM_PTRCONTENTS, ptr, CURLFORM_CONTENTSLENGTH, 10, CURLFORM_END);
 * (if CURLFORM_CONTENTSLENGTH is missing strlen () is used)
 *
 * storing a filename (CONTENTTYPE is optional!):
 * curl_formadd (&post, &last, CURLFORM_COPYNAME, "name",
 * CURLFORM_FILE, "filename1", CURLFORM_CONTENTTYPE, "plain/text",
 * CURLFORM_END);
 *
 * storing multiple filenames:
 * curl_formadd (&post, &last, CURLFORM_COPYNAME, "name",
 * CURLFORM_FILE, "filename1", CURLFORM_FILE, "filename2", CURLFORM_END);
 *
 * Returns:
 * CURL_FORMADD_OK             on success
 * CURL_FORMADD_MEMORY         if the FormInfo allocation fails
 * CURL_FORMADD_OPTION_TWICE   if one option is given twice for one Form
 * CURL_FORMADD_NULL           if a null pointer was given for a char
 * CURL_FORMADD_MEMORY         if the allocation of a FormInfo struct failed
 * CURL_FORMADD_UNKNOWN_OPTION if an unknown option was used
 * CURL_FORMADD_INCOMPLETE     if the some FormInfo is not complete (or an error)
 * CURL_FORMADD_MEMORY         if a HttpPost struct cannot be allocated
 * CURL_FORMADD_MEMORY         if some allocation for string copying failed.
 * CURL_FORMADD_ILLEGAL_ARRAY  if an illegal option is used in an array
 *
 ***************************************************************************/

static
CURLFORMcode FormAdd(struct curl_httppost **httppost,
                     struct curl_httppost **last_post,
                     va_list params)
{
  FormInfo *first_form, *current_form, *form;
  CURLFORMcode return_value = CURL_FORMADD_OK;
  const char *prevtype = NULL;
  struct curl_httppost *post = NULL;
  CURLformoption option;
  struct curl_forms *forms = NULL;
  char *array_value=NULL; /* value read from an array */

  /* This is a state variable, that if TRUE means that we're parsing an
     array that we got passed to us. If FALSE we're parsing the input
     va_list arguments. */
  bool array_state = FALSE;

  /*
   * We need to allocate the first struct to fill in.
   */
  first_form = (FormInfo *)malloc(sizeof(struct FormInfo));
  if(first_form) {
    memset(first_form, 0, sizeof(FormInfo));
    current_form = first_form;
  }
  else
    return CURL_FORMADD_MEMORY;

  /*
   * Loop through all the options set.
   */
  while (1) {

    /* break if we have an error to report */
    if (return_value != CURL_FORMADD_OK)
      break;

    /* first see if we have more parts of the array param */
    if ( array_state ) {
      /* get the upcoming option from the given array */
      option = forms->option;
      array_value = (char *)forms->value;

      forms++; /* advance this to next entry */
      if (CURLFORM_END == option) {
        /* end of array state */
        array_state = FALSE;
        continue;
      }
    }
    else {
      /* This is not array-state, get next option */
      option = va_arg(params, CURLformoption);
      if (CURLFORM_END == option)
        break;
    }

    switch (option) {
    case CURLFORM_ARRAY:
      if(array_state)
        /* we don't support an array from within an array */
        return_value = CURL_FORMADD_ILLEGAL_ARRAY;
      else {
        forms = va_arg(params, struct curl_forms *);
        if (forms)
          array_state = TRUE;
        else
          return_value = CURL_FORMADD_NULL;
      }
      break;

      /*
       * Set the Name property.
       */
    case CURLFORM_PTRNAME:
      current_form->flags |= HTTPPOST_PTRNAME; /* fall through */
    case CURLFORM_COPYNAME:
      if (current_form->name)
        return_value = CURL_FORMADD_OPTION_TWICE;
      else {
        char *name = array_state?
          array_value:va_arg(params, char *);
        if (name)
          current_form->name = name; /* store for the moment */
        else
          return_value = CURL_FORMADD_NULL;
      }
      break;
    case CURLFORM_NAMELENGTH:
      if (current_form->namelength)
        return_value = CURL_FORMADD_OPTION_TWICE;
      else
        current_form->namelength =
          array_state?(long)array_value:va_arg(params, long);
      break;

      /*
       * Set the contents property.
       */
    case CURLFORM_PTRCONTENTS:
      current_form->flags |= HTTPPOST_PTRCONTENTS; /* fall through */
    case CURLFORM_COPYCONTENTS:
      if (current_form->value)
        return_value = CURL_FORMADD_OPTION_TWICE;
      else {
        char *value =
          array_state?array_value:va_arg(params, char *);
        if (value)
          current_form->value = value; /* store for the moment */
        else
          return_value = CURL_FORMADD_NULL;
      }
      break;
    case CURLFORM_CONTENTSLENGTH:
      if (current_form->contentslength)
        return_value = CURL_FORMADD_OPTION_TWICE;
      else
        current_form->contentslength =
          array_state?(long)array_value:va_arg(params, long);
      break;

      /* Get contents from a given file name */
    case CURLFORM_FILECONTENT:
      if (current_form->flags != 0)
        return_value = CURL_FORMADD_OPTION_TWICE;
      else {
        char *filename = array_state?
          array_value:va_arg(params, char *);
        if (filename) {
          current_form->value = strdup(filename);
          current_form->flags |= HTTPPOST_READFILE;
        }
        else
          return_value = CURL_FORMADD_NULL;
      }
      break;

      /* We upload a file */
    case CURLFORM_FILE:
      {
        char *filename = array_state?array_value:
          va_arg(params, char *);

        if (current_form->value) {
          if (current_form->flags & HTTPPOST_FILENAME) {
            if (filename) {
              if (!(current_form = AddFormInfo(strdup(filename),
                                               NULL, current_form)))
                return_value = CURL_FORMADD_MEMORY;
            }
            else
              return_value = CURL_FORMADD_NULL;
          }
          else
            return_value = CURL_FORMADD_OPTION_TWICE;
        }
        else {
          if (filename)
            current_form->value = strdup(filename);
          else
            return_value = CURL_FORMADD_NULL;
          current_form->flags |= HTTPPOST_FILENAME;
        }
        break;
      }

    case CURLFORM_BUFFER:
      {
        char *filename = array_state?array_value:
          va_arg(params, char *);

        if (current_form->value) {
          if (current_form->flags & HTTPPOST_BUFFER) {
            if (filename) {
              if (!(current_form = AddFormInfo(strdup(filename),
                                               NULL, current_form)))
                return_value = CURL_FORMADD_MEMORY;
            }
            else
              return_value = CURL_FORMADD_NULL;
          }
          else
            return_value = CURL_FORMADD_OPTION_TWICE;
        }
        else {
          if (filename)
            current_form->value = strdup(filename);
          else
            return_value = CURL_FORMADD_NULL;
          current_form->flags |= HTTPPOST_BUFFER;
        }
        break;
      }
      
    case CURLFORM_BUFFERPTR:
        current_form->flags |= HTTPPOST_PTRBUFFER;
      if (current_form->buffer)
        return_value = CURL_FORMADD_OPTION_TWICE;
      else {
        char *buffer =
          array_state?array_value:va_arg(params, char *);
        if (buffer)
          current_form->buffer = buffer; /* store for the moment */
        else
          return_value = CURL_FORMADD_NULL;
      }
      break;

    case CURLFORM_BUFFERLENGTH:
      if (current_form->bufferlength)
        return_value = CURL_FORMADD_OPTION_TWICE;
      else
        current_form->bufferlength =
          array_state?(long)array_value:va_arg(params, long);
      break;

    case CURLFORM_CONTENTTYPE:
      {
        char *contenttype =
          array_state?array_value:va_arg(params, char *);
        if (current_form->contenttype) {
          if (current_form->flags & HTTPPOST_FILENAME) {
            if (contenttype) {
              if (!(current_form = AddFormInfo(NULL,
                                               strdup(contenttype),
                                               current_form)))
                return_value = CURL_FORMADD_MEMORY;
            }
	    else
	      return_value = CURL_FORMADD_NULL;
          }
          else
            return_value = CURL_FORMADD_OPTION_TWICE;
        }
        else {
	  if (contenttype)
	    current_form->contenttype = strdup(contenttype);
	  else
	    return_value = CURL_FORMADD_NULL;
	}
        break;
      }
    case CURLFORM_CONTENTHEADER:
      {
        /* this "cast increases required alignment of target type" but
           we consider it OK anyway */
        struct curl_slist* list = array_state?
          (struct curl_slist*)array_value:
          va_arg(params, struct curl_slist*);
        
        if( current_form->contentheader )
          return_value = CURL_FORMADD_OPTION_TWICE;
        else
          current_form->contentheader = list;
        
        break;
      }
    case CURLFORM_FILENAME:
      {
        char *filename = array_state?array_value:
          va_arg(params, char *);
        if( current_form->showfilename )
          return_value = CURL_FORMADD_OPTION_TWICE;
        else
          current_form->showfilename = strdup(filename);
        break;
      }
    default:
      return_value = CURL_FORMADD_UNKNOWN_OPTION;
    }
  }

  if(CURL_FORMADD_OK == return_value) {
    /* go through the list, check for copleteness and if everything is
     * alright add the HttpPost item otherwise set return_value accordingly */
    
    post = NULL;
    for(form = first_form;
        form != NULL;
        form = form->more) {
      if ( ((!form->name || !form->value) && !post) ||
           ( (form->contentslength) &&
             (form->flags & HTTPPOST_FILENAME) ) ||
           ( (form->flags & HTTPPOST_FILENAME) &&
             (form->flags & HTTPPOST_PTRCONTENTS) ) ||

           ( (!form->buffer) &&
             (form->flags & HTTPPOST_BUFFER) &&
             (form->flags & HTTPPOST_PTRBUFFER) ) ||

           ( (form->flags & HTTPPOST_READFILE) &&
             (form->flags & HTTPPOST_PTRCONTENTS) )
           ) {
        return_value = CURL_FORMADD_INCOMPLETE;
        break;
      }
      else {
        if ( ((form->flags & HTTPPOST_FILENAME) ||
              (form->flags & HTTPPOST_BUFFER)) &&
             !form->contenttype ) {
          /* our contenttype is missing */
          form->contenttype
            = strdup(ContentTypeForFilename(form->value, prevtype));
        }
        if ( !(form->flags & HTTPPOST_PTRNAME) &&
             (form == first_form) ) {
          /* copy name (without strdup; possibly contains null characters) */
          if (AllocAndCopy(&form->name, form->namelength)) {
            return_value = CURL_FORMADD_MEMORY;
            break;
          }
        }
        if ( !(form->flags & HTTPPOST_FILENAME) &&
             !(form->flags & HTTPPOST_READFILE) && 
             !(form->flags & HTTPPOST_PTRCONTENTS) &&
             !(form->flags & HTTPPOST_PTRBUFFER) ) {

          /* copy value (without strdup; possibly contains null characters) */
          if (AllocAndCopy(&form->value, form->contentslength)) {
            return_value = CURL_FORMADD_MEMORY;
            break;
          }
        }
        post = AddHttpPost(form->name, form->namelength,
                           form->value, form->contentslength,
                           form->buffer, form->bufferlength,
                           form->contenttype, form->flags,
                           form->contentheader, form->showfilename,
                           post, httppost,
                           last_post);
        
        if(!post)
          return_value = CURL_FORMADD_MEMORY;

        if (form->contenttype)
          prevtype = form->contenttype;
      }
    }
  }

  /* always delete the allocated memory before returning */
  form = first_form;
  while (form != NULL) {
    FormInfo *delete_form;
    
    delete_form = form;
    form = form->more;
    free (delete_form);
  }

  return return_value;
}

/*
 * curl_formadd() is a public API to add a section to the multipart formpost.
 */

CURLFORMcode curl_formadd(struct curl_httppost **httppost,
                          struct curl_httppost **last_post,
                          ...)
{
  va_list arg;
  CURLFORMcode result;
  va_start(arg, last_post);
  result = FormAdd(httppost, last_post, arg);
  va_end(arg);
  return result;
}

/*
 * AddFormData() adds a chunk of data to the FormData linked list.
 */
static size_t AddFormData(struct FormData **formp,
                          const void *line,
                          size_t length)
{
  struct FormData *newform = (struct FormData *)
    malloc(sizeof(struct FormData));
  newform->next = NULL;

  /* we make it easier for plain strings: */
  if(!length)
    length = strlen((char *)line);

  newform->line = (char *)malloc(length+1);
  memcpy(newform->line, line, length);
  newform->length = length;
  newform->line[length]=0; /* zero terminate for easier debugging */
  
  if(*formp) {
    (*formp)->next = newform;
    *formp = newform;
  }
  else
    *formp = newform;

  return length;
}

/*
 * AddFormDataf() adds printf()-style formatted data to the formdata chain.
 */

static size_t AddFormDataf(struct FormData **formp,
                           const char *fmt, ...)
{
  char s[4096];
  va_list ap;
  va_start(ap, fmt);
  vsprintf(s, fmt, ap);
  va_end(ap);

  return AddFormData(formp, s, 0);
}

/*
 * Curl_FormBoundary() creates a suitable boundary string and returns an
 * allocated one.
 */
char *Curl_FormBoundary(void)
{
  char *retstring;
  static int randomizer=0; /* this is just so that two boundaries within
			      the same form won't be identical */
  size_t i;

  static char table16[]="abcdef0123456789";

  retstring = (char *)malloc(BOUNDARY_LENGTH+1);

  if(!retstring)
    return NULL; /* failed */

  srand(time(NULL)+randomizer++); /* seed */

  strcpy(retstring, "----------------------------");

  for(i=strlen(retstring); i<BOUNDARY_LENGTH; i++)
    retstring[i] = table16[rand()%16];

  /* 28 dashes and 12 hexadecimal digits makes 12^16 (184884258895036416)
     combinations */
  retstring[BOUNDARY_LENGTH]=0; /* zero terminate */

  return retstring;
}

/*
 * Curl_formclean() is used from http.c, this cleans a built FormData linked
 * list
 */ 
void Curl_formclean(struct FormData *form)
{
  struct FormData *next;

  do {
    next=form->next;  /* the following form line */
    free(form->line); /* free the line */
    free(form);       /* free the struct */
  
  } while((form=next)); /* continue */
}

/*
 * curl_formfree() is an external function to free up a whole form post
 * chain
 */
void curl_formfree(struct curl_httppost *form)
{
  struct curl_httppost *next;

  if(!form)
    /* no form to free, just get out of this */
    return;

  do {
    next=form->next;  /* the following form line */

    /* recurse to sub-contents */
    if(form->more)
      curl_formfree(form->more);

    if( !(form->flags & HTTPPOST_PTRNAME) && form->name)
      free(form->name); /* free the name */
    if( !(form->flags & HTTPPOST_PTRCONTENTS) && form->contents)
      free(form->contents); /* free the contents */
    if(form->contenttype)
      free(form->contenttype); /* free the content type */
    if(form->showfilename)
      free(form->showfilename); /* free the faked file name */
    free(form);       /* free the struct */

  } while((form=next)); /* continue */
}

/*
 * Curl_getFormData() converts a linked list of "meta data" into a complete
 * (possibly huge) multipart formdata. The input list is in 'post', while the
 * output resulting linked lists gets stored in '*finalform'. *sizep will get
 * the total size of the whole POST.
 */

CURLcode Curl_getFormData(struct FormData **finalform,
                          struct curl_httppost *post,
                          curl_off_t *sizep)
{
  struct FormData *form = NULL;
  struct FormData *firstform;
  struct curl_httppost *file;
  CURLcode result = CURLE_OK;

  size_t size =0;
  char *boundary;
  char *fileboundary=NULL;
  struct curl_slist* curList;

  *finalform=NULL; /* default form is empty */

  if(!post)
    return result; /* no input => no output! */

  boundary = Curl_FormBoundary();
  
  /* Make the first line of the output */
  AddFormDataf(&form,
               "Content-Type: multipart/form-data;"
               " boundary=%s\r\n",
               boundary);
  /* we DO NOT count that line since that'll be part of the header! */

  firstform = form;
  
  do {

    if(size)
      size += AddFormDataf(&form, "\r\n");

    /* boundary */
    size += AddFormDataf(&form, "--%s\r\n", boundary);

    size += AddFormData(&form,
                        "Content-Disposition: form-data; name=\"", 0);

    size += AddFormData(&form, post->name, post->namelength);

    size += AddFormData(&form, "\"", 0);

    if(post->more) {
      /* If used, this is a link to more file names, we must then do
         the magic to include several files with the same field name */

      fileboundary = Curl_FormBoundary();

      size += AddFormDataf(&form,
                           "\r\nContent-Type: multipart/mixed,"
                           " boundary=%s\r\n",
                           fileboundary);
    }

    file = post;

    do {

      /* If 'showfilename' is set, that is a faked name passed on to us
         to use to in the formpost. If that is not set, the actually used
         local file name should be added. */

      if(post->more) {
        /* if multiple-file */
        size += AddFormDataf(&form,
                             "\r\n--%s\r\nContent-Disposition: "
                             "attachment; filename=\"%s\"",
                             fileboundary,
                             (file->showfilename?file->showfilename:
                              file->contents));
      }
      else if((post->flags & HTTPPOST_FILENAME) ||
              (post->flags & HTTPPOST_BUFFER)) {

        size += AddFormDataf(&form,
                             "; filename=\"%s\"",
                             (post->showfilename?post->showfilename:
                              post->contents));
      }
      
      if(file->contenttype) {
        /* we have a specified type */
        size += AddFormDataf(&form,
                             "\r\nContent-Type: %s",
                             file->contenttype);
      }

      curList = file->contentheader;
      while( curList ) {
        /* Process the additional headers specified for this form */
        size += AddFormDataf( &form, "\r\n%s", curList->data );
        curList = curList->next;
      }

#if 0
      /* The header Content-Transfer-Encoding: seems to confuse some receivers
       * (like the built-in PHP engine). While I can't see any reason why it
       * should, I can just as well skip this to the benefit of the users who