path: root/lib/formdata.c

/***************************************************************************
 *                                  _   _ ____  _
 *  Project                     ___| | | |  _ \| |
 *                             / __| | | | |_) | |
 *                            | (__| |_| |  _ <| |___
 *                             \___|\___/|_| \_\_____|
 *
 * Copyright (C) 1998 - 2017, 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 https://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.
 *
 ***************************************************************************/

#include "curl_setup.h"

#include <curl/curl.h>

#ifndef CURL_DISABLE_HTTP

#if defined(HAVE_LIBGEN_H) && defined(HAVE_BASENAME)
#include <libgen.h>
#endif

#include "urldata.h" /* for struct Curl_easy */
#include "formdata.h"
#include "vtls/vtls.h"
#include "strcase.h"
#include "sendf.h"
#include "strdup.h"
#include "rand.h"
/* The last 3 #include files should be in this order */
#include "curl_printf.h"
#include "curl_memory.h"
#include "memdebug.h"

#ifndef HAVE_BASENAME
static char *Curl_basename(char *path);
#define basename(x)  Curl_basename((x))
#endif

static size_t readfromfile(struct Form *form, char *buffer, size_t size);
static CURLcode formboundary(struct Curl_easy *data, char *buffer, size_t len);

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

#define HTTPPOST_PTRNAME CURL_HTTPPOST_PTRNAME
#define HTTPPOST_FILENAME CURL_HTTPPOST_FILENAME
#define HTTPPOST_PTRCONTENTS CURL_HTTPPOST_PTRCONTENTS
#define HTTPPOST_READFILE CURL_HTTPPOST_READFILE
#define HTTPPOST_PTRBUFFER CURL_HTTPPOST_PTRBUFFER
#define HTTPPOST_CALLBACK CURL_HTTPPOST_CALLBACK
#define HTTPPOST_BUFFER CURL_HTTPPOST_BUFFER

/***************************************************************************
 *
 * 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, curl_off_t contentslength,
            char *buffer, size_t bufferlength,
            char *contenttype,
            long flags,
            struct curl_slist *contentHeader,
            char *showfilename, char *userp,
            struct curl_httppost *parent_post,
            struct curl_httppost **httppost,
            struct curl_httppost **last_post)
{
  struct curl_httppost *post;
  post = calloc(1, sizeof(struct curl_httppost));
  if(post) {
    post->name = name;
    post->namelength = (long)(name?(namelength?namelength:strlen(name)):0);
    post->contents = value;
    post->contentlen = contentslength;
    post->buffer = buffer;
    post->bufferlength = (long)bufferlength;
    post->contenttype = contenttype;
    post->contentheader = contentHeader;
    post->showfilename = showfilename;
    post->userp = userp;
    post->flags = flags | CURL_HTTPPOST_LARGE;
  }
  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 = calloc(1, sizeof(struct FormInfo));
  if(form_info) {
    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;
  }

  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 const struct ContentType ctts[]={
    {".gif",  "image/gif"},
    {".jpg",  "image/jpeg"},
    {".jpeg", "image/jpeg"},
    {".txt",  "text/plain"},
    {".html", "text/html"},
    {".xml", "application/xml"}
  };

  if(prevtype)
    /* default to the previously set/used! */
    contenttype = prevtype;
  else
    contenttype = HTTPPOST_CONTENTTYPE_DEFAULT;

  if(filename) { /* in case a NULL was passed in */
    for(i=0; i<sizeof(ctts)/sizeof(ctts[0]); i++) {
      if(strlen(filename) >= strlen(ctts[i].extension)) {
        if(strcasecompare(filename +
                          strlen(filename) - strlen(ctts[i].extension),
                          ctts[i].extension)) {
          contenttype = ctts[i].type;
          break;
        }
      }
    }
  }
  /* we have a contenttype by now */
  return contenttype;
}

/***************************************************************************
 *
 * FormAdd()
 *
 * Stores a 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 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 = NULL;
  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 = calloc(1, sizeof(struct FormInfo));
  if(!first_form)
    return CURL_FORMADD_MEMORY;

  current_form = first_form;

  /*
   * Loop through all the options set. Break if we have an error to report.
   */
  while(return_value == CURL_FORMADD_OK) {

    /* first see if we have more parts of the array param */
    if(array_state && forms) {
      /* 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:
#ifdef CURL_DOES_CONVERSIONS
      /* Treat CURLFORM_PTR like CURLFORM_COPYNAME so that libcurl will copy
       * the data in all cases so that we'll have safe memory for the eventual
       * conversion.
       */
#else
      current_form->flags |= HTTPPOST_PTRNAME; /* fall through */
#endif
      /* FALLTHROUGH */
    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?(size_t)array_value:(size_t)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:
      current_form->contentslength =
        array_state?(size_t)array_value:(size_t)va_arg(params, long);
      break;

    case CURLFORM_CONTENTLEN:
      current_form->flags |= CURL_HTTPPOST_LARGE;
      current_form->contentslength =
        array_state?(curl_off_t)(size_t)array_value:va_arg(params, curl_off_t);
      break;

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

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

        if(current_form->value) {
          if(current_form->flags & HTTPPOST_FILENAME) {
            if(filename) {
              char *fname = strdup(filename);
              if(!fname)
                return_value = CURL_FORMADD_MEMORY;
              else {
                form = AddFormInfo(fname, NULL, current_form);
                if(!form) {
                  free(fname);
                  return_value = CURL_FORMADD_MEMORY;
                }
                else {
                  form->value_alloc = TRUE;
                  current_form = form;
                  form = NULL;
                }
              }
            }
            else
              return_value = CURL_FORMADD_NULL;
          }
          else
            return_value = CURL_FORMADD_OPTION_TWICE;
        }
        else {
          if(filename) {
            current_form->value = strdup(filename);
            if(!current_form->value)
              return_value = CURL_FORMADD_MEMORY;
            else {
              current_form->flags |= HTTPPOST_FILENAME;
              current_form->value_alloc = TRUE;
            }
          }
          else
            return_value = CURL_FORMADD_NULL;
        }
        break;
      }

    case CURLFORM_BUFFERPTR:
      current_form->flags |= HTTPPOST_PTRBUFFER|HTTPPOST_BUFFER;
      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 */
          current_form->value = buffer; /* make it non-NULL to be accepted
                                           as fine */
        }
        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?(size_t)array_value:(size_t)va_arg(params, long);
      break;

    case CURLFORM_STREAM:
      current_form->flags |= HTTPPOST_CALLBACK;
      if(current_form->userp)
        return_value = CURL_FORMADD_OPTION_TWICE;
      else {
        char *userp =
          array_state?array_value:va_arg(params, char *);
        if(userp) {
          current_form->userp = userp;
          current_form->value = userp; /* this isn't strictly true but we
                                          derive a value from this later on
                                          and we need this non-NULL to be
                                          accepted as a fine form part */
        }
        else
          return_value = CURL_FORMADD_NULL;
      }
      break;

    case CURLFORM_CONTENTTYPE:
      {
        const char *contenttype =
          array_state?array_value:va_arg(params, char *);
        if(current_form->contenttype) {
          if(current_form->flags & HTTPPOST_FILENAME) {
            if(contenttype) {
              char *type = strdup(contenttype);
              if(!type)
                return_value = CURL_FORMADD_MEMORY;
              else {
                form = AddFormInfo(NULL, type, current_form);
                if(!form) {
                  free(type);
                  return_value = CURL_FORMADD_MEMORY;
                }
                else {
                  form->contenttype_alloc = TRUE;
                  current_form = form;
                  form = NULL;
                }
              }
            }
            else
              return_value = CURL_FORMADD_NULL;
          }
          else
            return_value = CURL_FORMADD_OPTION_TWICE;
        }
        else {
          if(contenttype) {
            current_form->contenttype = strdup(contenttype);
            if(!current_form->contenttype)
              return_value = CURL_FORMADD_MEMORY;
            else
              current_form->contenttype_alloc = TRUE;
          }
          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 *)(void *)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:
    case CURLFORM_BUFFER:
      {
        const 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);
          if(!current_form->showfilename)
            return_value = CURL_FORMADD_MEMORY;
          else
            current_form->showfilename_alloc = TRUE;
        }
        break;
      }
    default:
      return_value = CURL_FORMADD_UNKNOWN_OPTION;
      break;
    }
  }

  if(CURL_FORMADD_OK != return_value) {
    /* On error, free allocated fields for all nodes of the FormInfo linked
       list without deallocating nodes. List nodes are deallocated later on */
    FormInfo *ptr;
    for(ptr = first_form; ptr != NULL; ptr = ptr->more) {
      if(ptr->name_alloc) {
        Curl_safefree(ptr->name);
        ptr->name_alloc = FALSE;
      }
      if(ptr->value_alloc) {
        Curl_safefree(ptr->value);
        ptr->value_alloc = FALSE;
      }
      if(ptr->contenttype_alloc) {
        Curl_safefree(ptr->contenttype);
        ptr->contenttype_alloc = FALSE;
      }
      if(ptr->showfilename_alloc) {
        Curl_safefree(ptr->showfilename);
        ptr->showfilename_alloc = FALSE;
      }
    }
  }

  if(CURL_FORMADD_OK == return_value) {
    /* go through the list, check for completeness 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;
      }
      if(((form->flags & HTTPPOST_FILENAME) ||
          (form->flags & HTTPPOST_BUFFER)) &&
         !form->contenttype) {
        char *f = form->flags & HTTPPOST_BUFFER?
          form->showfilename : form->value;

        /* our contenttype is missing */
        form->contenttype = strdup(ContentTypeForFilename(f, prevtype));
        if(!form->contenttype) {
          return_value = CURL_FORMADD_MEMORY;
          break;
        }
        form->contenttype_alloc = TRUE;
      }
      if(!(form->flags & HTTPPOST_PTRNAME) &&
         (form == first_form) ) {
        /* Note that there's small risk that form->name is NULL here if the
           app passed in a bad combo, so we better check for that first. */
        if(form->name) {
          /* copy name (without strdup; possibly contains null characters) */
          form->name = Curl_memdup(form->name, form->namelength?
                                   form->namelength:
                                   strlen(form->name)+1);
        }
        if(!form->name) {
          return_value = CURL_FORMADD_MEMORY;
          break;
        }
        form->name_alloc = TRUE;
      }
      if(!(form->flags & (HTTPPOST_FILENAME | HTTPPOST_READFILE |
                          HTTPPOST_PTRCONTENTS | HTTPPOST_PTRBUFFER |
                          HTTPPOST_CALLBACK)) && form->value) {
        /* copy value (without strdup; possibly contains null characters) */
        size_t clen  = (size_t) form->contentslength;
        if(!clen)
          clen = strlen(form->value)+1;

        form->value = Curl_memdup(form->value, clen);

        if(!form->value) {
          return_value = CURL_FORMADD_MEMORY;
          break;
        }
        form->value_alloc = TRUE;
      }
      post = AddHttpPost(form->name, form->namelength,
                         form->value, form->contentslength,
                         form->buffer, form->bufferlength,
                         form->contenttype, form->flags,
                         form->contentheader, form->showfilename,
                         form->userp,
                         post, httppost,
                         last_post);

      if(!post) {
        return_value = CURL_FORMADD_MEMORY;
        break;
      }

      if(form->contenttype)
        prevtype = form->contenttype;
    }
    if(CURL_FORMADD_OK != return_value) {
      /* On error, free allocated fields for nodes of the FormInfo linked
         list which are not already owned by the httppost linked list
         without deallocating nodes. List nodes are deallocated later on */
      FormInfo *ptr;
      for(ptr = form; ptr != NULL; ptr = ptr->more) {
        if(ptr->name_alloc) {
          Curl_safefree(ptr->name);
          ptr->name_alloc = FALSE;
        }
        if(ptr->value_alloc) {
          Curl_safefree(ptr->value);
          ptr->value_alloc = FALSE;
        }
        if(ptr->contenttype_alloc) {
          Curl_safefree(ptr->contenttype);
          ptr->contenttype_alloc = FALSE;
        }
        if(ptr->showfilename_alloc) {
          Curl_safefree(ptr->showfilename);
          ptr->showfilename_alloc = FALSE;
        }
      }
    }
  }

  /* Always deallocate FormInfo linked list nodes without touching node
     fields given that these have either been deallocated or are owned
     now by the httppost linked list */
  while(first_form) {
    FormInfo *ptr = first_form->more;
    free(first_form);
    first_form = ptr;
  }

  return return_value;
}

/*
 * curl_formadd() is a public API to add a section to the multipart formpost.
 *
 * @unittest: 1308
 */

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;
}

#ifdef __VMS
#include <fabdef.h>
/*
 * get_vms_file_size does what it takes to get the real size of the file
 *
 * For fixed files, find out the size of the EOF block and adjust.
 *
 * For all others, have to read the entire file in, discarding the contents.
 * Most posted text files will be small, and binary files like zlib archives
 * and CD/DVD images should be either a STREAM_LF format or a fixed format.
 *
 */
curl_off_t VmsRealFileSize(const char *name,
                           const struct_stat *stat_buf)
{
  char buffer[8192];
  curl_off_t count;
  int ret_stat;
  FILE * file;

  file = fopen(name, FOPEN_READTEXT); /* VMS */
  if(file == NULL)
    return 0;

  count = 0;
  ret_stat = 1;
  while(ret_stat > 0) {
    ret_stat = fread(buffer, 1, sizeof(buffer), file);
    if(ret_stat != 0)
      count += ret_stat;
  }
  fclose(file);

  return count;
}

/*
 *
 *  VmsSpecialSize checks to see if the stat st_size can be trusted and
 *  if not to call a routine to get the correct size.
 *
 */
static curl_off_t VmsSpecialSize(const char *name,
                                 const struct_stat *stat_buf)
{
  switch(stat_buf->st_fab_rfm) {
  case FAB$C_VAR:
  case FAB$C_VFC:
    return VmsRealFileSize(name, stat_buf);
    break;
  default:
    return stat_buf->st_size;
  }
}

#endif

#ifndef __VMS
#define filesize(name, stat_data) (stat_data.st_size)
#else
    /* Getting the expected file size needs help on VMS */
#define filesize(name, stat_data) VmsSpecialSize(name, &stat_data)
#endif

/*
 * AddFormData() adds a chunk of data to the FormData linked list.
 *
 * size is incremented by the chunk length, unless it is NULL
 */
static CURLcode AddFormData(struct FormData **formp,
                            enum formtype type,
                            const void *line,
                            curl_off_t length,
                            curl_off_t *size)
{
  struct FormData *newform;
  char *alloc2 = NULL;
  CURLcode result = CURLE_OK;
  if(length < 0 || (size && *size < 0))
    return CURLE_BAD_FUNCTION_ARGUMENT;

  newform = malloc(sizeof(struct FormData));
  if(!newform)
    return CURLE_OUT_OF_MEMORY;
  newform->next = NULL;

  if(type <= FORM_CONTENT) {
    /* we make it easier for plain strings: */
    if(!length)
      length = strlen((char *)line);
#if (SIZEOF_SIZE_T < CURL_SIZEOF_CURL_OFF_T)
    else if(length >= (curl_off_t)(size_t)-1) {
      result = CURLE_BAD_FUNCTION_ARGUMENT;
      goto error;
    }
#endif
    if(type != FORM_DATAMEM) {
      newform->line = malloc((size_t)length+1);
      if(!newform->line) {
        result = CURLE_OUT_OF_MEMORY;
        goto error;
      }
      alloc2 = newform->line;
      memcpy(newform->line, line, (size_t)length);

      /* zero terminate for easier debugging */
      newform->line[(size_t)length]=0;
    }
    else {
      newform->line = (char *)line;
      type = FORM_DATA; /* in all other aspects this is just FORM_DATA */
    }
    newform->length = (size_t)length;
  }
  else
    /* For callbacks and files we don't have any actual data so we just keep a
       pointer to whatever this points to */
    newform->line = (char *)line;

  newform->type = type;

  if(size) {
    if(type != FORM_FILE)
      /* for static content as well as callback data we add the size given
         as input argument */
      *size += length;
    else {
      /* Since this is a file to be uploaded here, add the size of the actual
         file */
      if(strcmp("-", newform->line)) {
        struct_stat file;
        if(!stat(newform->line, &file) && !S_ISDIR(file.st_mode))
          *size += filesize(newform->line, file);
        else {
          result = CURLE_BAD_FUNCTION_ARGUMENT;
          goto error;
        }
      }
    }
  }

  if(*formp) {
    (*formp)->next = newform;
    *formp = newform;
  }
  else
    *formp = newform;

  return CURLE_OK;
  error:
  if(newform)
    free(newform);
  if(alloc2)
    free(alloc2);
  return result;
}

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

static CURLcode AddFormDataf(struct FormData **formp,
                             curl_off_t *size,
                             const char *fmt, ...)
{
  char *s;
  CURLcode result;
  va_list ap;
  va_start(ap, fmt);
  s = curl_mvaprintf(fmt, ap);
  va_end(ap);

  if(!s)
    return CURLE_OUT_OF_MEMORY;

  result = AddFormData(formp, FORM_DATAMEM, s, 0, size);
  if(result)
    free(s);

  return result;
}

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

  form = *form_ptr;
  if(!form)
    return;

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

  *form_ptr = NULL;
}

/*
 * curl_formget()
 * Serialize a curl_httppost struct.
 * Returns 0 on success.
 *
 * @unittest: 1308
 */
int curl_formget(struct curl_httppost *form, void *arg,
                 curl_formget_callback append)
{
  CURLcode result;
  curl_off_t size;
  struct FormData *data, *ptr;

  result = Curl_getformdata(NULL, &data, form, NULL, &size);
  if(result)
    return (int)result;

  for(ptr = data; ptr; ptr = ptr->next) {
    if((ptr->type == FORM_FILE) || (ptr->type == FORM_CALLBACK)) {
      char buffer[8192];
      size_t nread;
      struct Form temp;

      Curl_FormInit(&temp, ptr);

      do {
        nread = readfromfile(&temp, buffer, sizeof(buffer));
        if((nread == (size_t) -1) ||
           (nread > sizeof(buffer)) ||
           (nread != append(arg, buffer, nread))) {
          if(temp.fp)
            fclose(temp.fp);
          Curl_formclean(&data);
          return -1;
        }
      } while(nread);
    }
    else {
      if(ptr->length != append(arg, ptr->line, ptr->length)) {
        Curl_formclean(&data);
        return -1;
      }
    }
  }
  Curl_formclean(&data);
  return 0;
}

/*
 * 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 */
    curl_formfree(form->more);

    if(!(form->flags & HTTPPOST_PTRNAME))
      free(form->name); /* free the name */
    if(!(form->flags &
         (HTTPPOST_PTRCONTENTS|HTTPPOST_BUFFER|HTTPPOST_CALLBACK))
      )
      free(form->contents); /* free the contents */
    free(form->contenttype); /* free the content type */
    free(form->showfilename); /* free the faked file name */
    free(form);       /* free the struct */
    form = next;
  } while(form); /* continue */
}

#ifndef HAVE_BASENAME
/*
  (Quote from The Open Group Base Specifications Issue 6 IEEE Std 1003.1, 2004
  Edition)

  The basename() function shall take the pathname pointed to by path and
  return a pointer to the final component of the pathname, deleting any
  trailing '/' characters.

  If the string pointed to by path consists entirely of the '/' character,
  basename() shall return a pointer to the string "/". If the string pointed
  to by path is exactly "//", it is implementation-defined whether '/' or "//"
  is returned.

  If path is a null pointer or points to an empty string, basename() shall
  return a pointer to the string ".".

  The basename() function may modify the string pointed to by path, and may
  return a pointer to static storage that may then be overwritten by a
  subsequent call to basename().

  The basename() function need not be reentrant. A function that is not
  required to be reentrant is not required to be thread-safe.

*/
static char *Curl_basename(char *path)
{
  /* Ignore all the details above for now and make a quick and simple
     implementaion here */
  char *s1;
  char *s2;

  s1=strrchr(path, '/');
  s2=strrchr(path, '\\');

  if(s1 && s2) {
    path = (s1 > s2? s1 : s2)+1;
  }
  else if(s1)
    path = s1 + 1;
  else if(s2)
    path = s2 + 1;

  return path;
}
#endif

static char *strippath(const char *fullfile)
{
  char *filename;
  char *base;
  filename = strdup(fullfile); /* duplicate since basename() may ruin the
                                  buffer it works on */
  if(!filename)
    return NULL;
  base = strdup(basename(filename));

  free(filename); /* free temporary buffer */

  return base; /* returns an allocated string or NULL ! */
}

static CURLcode formdata_add_filename(const struct curl_httppost *file,
                                      struct FormData **form,
                                      curl_off_t *size)
{
  CURLcode result = CURLE_OK;
  char *filename = file->showfilename;
  char *filebasename = NULL;
  char *filename_escaped = NULL;

  if(!filename) {
    filebasename = strippath(file->contents);
    if(!filebasename)
      return CURLE_OUT_OF_MEMORY;
    filename = filebasename;
  }

  if(strchr(filename, '\\') || strchr(filename, '"')) {
    char *p0, *p1;

    /* filename need be escaped */
    filename_escaped = malloc(strlen(filename)*2+1);
    if(!filename_escaped) {
      free(filebasename);
      return CURLE_OUT_OF_MEMORY;
    }
    p0 = filename_escaped;
    p1 = filename;
    while(*p1) {
      if(*p1 == '\\' || *p1 == '"')
        *p0++ = '\\';
      *p0++ = *p1++;
    }
    *p0 = '\0';
    filename = filename_escaped;
  }
  result = AddFormDataf(form, size,
                        "; filename=\"%s\"",
                        filename);
  free(filename_escaped);
  free(filebasename);
  return result;
}

/*
 * 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.
 * A multipart/form_data content-type is built, unless a custom content-type
 * is passed in 'custom_content_type'.
 *
 * This function will not do a failf() for the potential memory failures but
 * should for all other errors it spots. Just note that this function MAY get
 * a NULL pointer in the 'data' argument.
 */

CURLcode Curl_getformdata(struct Curl_easy *data,
                          struct FormData **finalform,
                          struct curl_httppost *post,
                          const char *custom_content_type,
                          curl_off_t *sizep)
{
  struct FormData *form = NULL;
  struct FormData *firstform;
  struct curl_httppost *file;
  CURLcode result = CURLE_OK;
  curl_off_t size = 0; /* support potentially ENORMOUS formposts */
  char fileboundary[42];
  struct curl_slist *curList;
  char boundary[42];

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

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

  result = formboundary(data, boundary, sizeof(boundary));
  if(result)
    return result;

  /* Make the first line of the output */
  result = AddFormDataf(&form, NULL,
                        "%s; boundary=%s\r\n",
                        custom_content_type?custom_content_type:
                        "Content-Type: multipart/form-data",
                        boundary);

  if(result) {
    return result;
  }
  /* we DO NOT include that line in the total size of the POST, since it'll be
     part of the header! */

  firstform = form;

  do {

    if(size) {
      result = AddFormDataf(&form, &size, "\r\n");
      if(result)
        break;
    }

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

    /* Maybe later this should be disabled when a custom_content_type is
       passed, since Content-Disposition is not meaningful for all multipart
       types.
    */
    result = AddFormDataf(&form, &size,
                          "Content-Disposition: form-data; name=\"");
    if(result)
      break;

    result = AddFormData(&form, FORM_DATA, post->name, post->namelength,
                         &size);
    if(result)
      break;

    result = AddFormDataf(&form, &size, "\"");
    if(result)
      break;

    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 */

      result = formboundary(data, fileboundary, sizeof(fileboundary));
      if(result) {
        break;
      }

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

    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 */
        result = AddFormDataf(&form, &size,
                              "\r\n--%s\r\nContent-Disposition: "
                              "attachment",
                              fileboundary);
        if(result)
          break;
        result = formdata_add_filename(file, &form, &size);
        if(result)
          break;
      }
      else if(post->flags & (HTTPPOST_FILENAME|HTTPPOST_BUFFER|
                             HTTPPOST_CALLBACK)) {
        /* it should be noted that for the HTTPPOST_FILENAME and
           HTTPPOST_CALLBACK cases the ->showfilename struct member is always
           assigned at this point */
        if(post->showfilename || (post->flags & HTTPPOST_FILENAME)) {
          result = formdata_add_filename(post, &form, &size);
        }

        if(result)
          break;
      }

      if(file->contenttype) {
        /* we have a specified type */
        result = AddFormDataf(&form, &size,
                              "\r\nContent-Type: %s",
                              file->contenttype);
        if(result)
          break;
      }

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

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

      if((post->flags & HTTPPOST_FILENAME) ||
         (post->flags & HTTPPOST_READFILE)) {
        /* we should include the contents from the specified file */
        FILE *fileread;

        fileread = !strcmp("-", file->contents)?
          stdin:fopen(file->contents, "rb"); /* binary read for win32  */

        /*
         * VMS: This only allows for stream files on VMS.  Stream files are
         * OK, as are FIXED & VAR files WITHOUT implied CC For implied CC,
         * every record needs to have a \n appended & 1 added to SIZE
         */

        if(fileread) {
          if(fileread != stdin) {
            /* close the file */
            fclose(fileread);
            /* add the file name only - for later reading from this */
            result = AddFormData(&form, FORM_FILE, file->contents, 0, &size);
          }
          else {
            /* When uploading from stdin, we can't know the size of the file,
             * thus must read the full file as before. We *could* use chunked
             * transfer-encoding, but that only works for HTTP 1.1 and we
             * can't be sure we work with such a server.
             */
            size_t nread;
            char buffer[512];
            while((nread = fread(buffer, 1, sizeof(buffer), fileread)) != 0) {
              result = AddFormData(&form, FORM_CONTENT, buffer, nread, &size);
              if(result || feof(fileread) || ferror(fileread))
                break;
            }
          }
        }
        else {
          if(data)
            failf(data, "couldn't open file \"%s\"", file->contents);
          *finalform = NULL;
          result = CURLE_READ_ERROR;
        }
      }
      else if(post->flags & HTTPPOST_BUFFER)
        /* include contents of buffer */
        result = AddFormData(&form, FORM_CONTENT, post->buffer,
                             post->bufferlength, &size);
      else if(post->flags & HTTPPOST_CALLBACK)
        /* the contents should be read with the callback and the size is set
           with the contentslength */
        result = AddFormData(&form, FORM_CALLBACK, post->userp,
                             post->flags&CURL_HTTPPOST_LARGE?
                             post->contentlen:post->contentslength, &size);
      else
        /* include the contents we got */
        result = AddFormData(&form, FORM_CONTENT, post->contents,
                             post->flags&CURL_HTTPPOST_LARGE?
                             post->contentlen:post->contentslength, &size);
      file = file->more;
    } while(file && !result); /* for each specified file for this field */

    if(result)
      break;

    if(post->more) {
      /* this was a multiple-file inclusion, make a termination file
         boundary: */
      result = AddFormDataf(&form, &size,
                           "\r\n--%s--",
                           fileboundary);
      if(result)
        break;
    }
    post = post->next;
  } while(post); /* for each field */

  /* end-boundary for everything */
  if(!result)
    result = AddFormDataf(&form, &size, "\r\n--%s--\r\n", boundary);

  if(result) {
    Curl_formclean(&firstform);
    return result;
  }

  *sizep = size;
  *finalform = firstform;

  return result;
}

/*
 * Curl_FormInit() inits the struct 'form' points to with the 'formdata'
 * and resets the 'sent' counter.
 */
int Curl_FormInit(struct Form *form, struct FormData *formdata)
{
  if(!formdata)
    return 1; /* error */

  form->data = formdata;
  form->sent = 0;
  form->fp = NULL;
  form->fread_func = ZERO_NULL;

  return 0;
}

#ifndef __VMS
# define fopen_read fopen
#else
  /*
   * vmsfopenread
   *
   * For upload to work as expected on VMS, different optional
   * parameters must be added to the fopen command based on
   * record format of the file.
   *
   */
# define fopen_read vmsfopenread
static FILE * vmsfopenread(const char *file, const char *mode)
{
  struct_stat statbuf;
  int result;

  result = stat(file, &statbuf);

  switch(statbuf.st_fab_rfm) {
  case FAB$C_VAR:
  case FAB$C_VFC:
  case FAB$C_STMCR:
    return fopen(file, FOPEN_READTEXT); /* VMS */
    break;
  default:
    return fopen(file, FOPEN_READTEXT, "rfm=stmlf", "ctx=stm");
  }
}
#endif

/*
 * readfromfile()
 *
 * The read callback that this function may use can return a value larger than
 * 'size' (which then this function returns) that indicates a problem and it
 * must be properly dealt with
 */
static size_t readfromfile(struct Form *form, char *buffer,
                           size_t size)
{
  size_t nread;
  bool callback = (form->data->type == FORM_CALLBACK)?TRUE:FALSE;

  if(callback) {
    if(form->fread_func == ZERO_NULL)
      return 0;
    nread = form->fread_func(buffer, 1, size, form->data->line);
  }
  else {
    if(!form->fp) {
      /* this file hasn't yet been opened */
      form->fp = fopen_read(form->data->line, "rb"); /* b is for binary */
      if(!form->fp)
        return (size_t)-1; /* failure */
    }
    nread = fread(buffer, 1, size, form->fp);
  }
  if(!nread) {
    /* this is the last chunk from the file, move on */
    if(form->fp) {
      fclose(form->fp);
      form->fp = NULL;
    }
    form->data = form->data->next;
  }

  return nread;
}

/*
 * Curl_FormReader() is the fread() emulation function that will be used to
 * deliver the formdata to the transfer loop and then sent away to the peer.
 */
size_t Curl_FormReader(char *buffer,
                       size_t size,
                       size_t nitems,
                       FILE *mydata)
{
  struct Form *form;
  size_t wantedsize;
  size_t gotsize = 0;

  form=(struct Form *)mydata;

  wantedsize = size * nitems;

  if(!form->data)
    return 0; /* nothing, error, empty */

  if((form->data->type == FORM_FILE) ||
     (form->data->type == FORM_CALLBACK)) {
    gotsize = readfromfile(form, buffer, wantedsize);

    if(gotsize)
      /* If positive or -1, return. If zero, continue! */
      return gotsize;
  }
  do {

    if((form->data->length - form->sent) > wantedsize - gotsize) {

      memcpy(buffer + gotsize, form->data->line + form->sent,
             wantedsize - gotsize);

      form->sent += wantedsize-gotsize;

      return wantedsize;
    }

    memcpy(buffer+gotsize,
           form->data->line + form->sent,
           (form->data->length - form->sent) );
    gotsize += form->data->length - form->sent;

    form->sent = 0;

    form->data = form->data->next; /* advance */

  } while(form->data && (form->data->type < FORM_CALLBACK));
  /* If we got an empty line and we have more data, we proceed to the next
     line immediately to avoid returning zero before we've reached the end. */

  return gotsize;
}

/*
 * Curl_formpostheader() returns the first line of the formpost, the
 * request-header part (which is not part of the request-body like the rest of
 * the post).
 */
char *Curl_formpostheader(void *formp, size_t *len)
{
  char *header;
  struct Form *form=(struct Form *)formp;

  if(!form->data)
    return NULL; /* nothing, ERROR! */

  header = form->data->line;
  *len = form->data->length;

  form->data = form->data->next; /* advance */

  return header;
}

/*
 * formboundary() creates a suitable boundary string and returns an allocated
 * one.
 */
static CURLcode formboundary(struct Curl_easy *data,
                             char *buffer, size_t buflen)
{
  /* 24 dashes and 16 hexadecimal digits makes 64 bit (18446744073709551615)
     combinations */
  if(buflen < 41)
    return CURLE_BAD_FUNCTION_ARGUMENT;

  memset(buffer, '-', 24);
  Curl_rand_hex(data, (unsigned char *)&buffer[24], 17);

  return CURLE_OK;
}

#else  /* CURL_DISABLE_HTTP */
CURLFORMcode curl_formadd(struct curl_httppost **httppost,
                          struct curl_httppost **last_post,
                          ...)
{
  (void)httppost;
  (void)last_post;
  return CURL_FORMADD_DISABLED;
}

int curl_formget(struct curl_httppost *form, void *arg,
                 curl_formget_callback append)
{
  (void) form;
  (void) arg;
  (void) append;
  return CURL_FORMADD_DISABLED;
}

void curl_formfree(struct curl_httppost *form)
{
  (void)form;
  /* does nothing HTTP is disabled */
}


#endif  /* !defined(CURL_DISABLE_HTTP) */