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/*-------------------------------------------------------------*/
/***************************************************************
 * A netwib_buf is the standard memory storage used in netwib. *
 *                                                             *
 * A netwib_buf points to an array (static or malloced) which  *
 * starts at 'first' and finishes at 'last'.                   *
 * The memory contains data between 'begin' and 'end'.         *
 *    ---------------------------------------------------      *
 *    |       |               data              |       |      *
 *    |F|     |B|                               |E|     |L     *
 *    ---------------------------------------------------      *
 *   First   Begin                              End    Last    *
 *     0       x                                 y   totalsize *
 *                                                             *
 ***************************************************************/

/*-------------------------------------------------------------*/
typedef struct {
  netwib_uint32 flags;       /* see below */
  netwib_data totalptr;      /* ptr to first */
  netwib_uint32 totalsize;   /* last - first */
  netwib_uint32 beginoffset; /* begin - first */
  netwib_uint32 endoffset;   /* end - first */
} netwib_buf;
typedef const netwib_buf netwib_constbuf;

/*-------------------------------------------------------------*/
/***************************************************************
 * Field "flags" is a bit field indicating some information    *
 * about a netwib_buf.                                         *
 ***************************************************************/

/* If totalptr points :
     0x0001 : to an allocated memory
    !0x0001 : to an external array (stack array or array which
              does not need to be freed)
   Those two modes corresponds to the two ways to initialize a
   netwib_buf :
     - netwib_buf_init_malloc : it internally allocates memory
       and eventually reallocate it if more is needed. At the
       end, function netwib_buf_close must be called to free
       memory.
     - netwib_buf_init_ext_xyz : buffer does not contain memory,
       but points on an external array. At the end, function
       netwib_buf_close does not need to be called to free
       memory (no closing function is needed).
   This flag should not be directly modified by user.
 */
#define NETWIB_BUF_FLAGS_ALLOC 0x00000001u

/* In the following case :
     - flag NETWIB_BUF_FLAGS_ALLOC is unset, and
     - there is no sufficient space in the array
   we can :
     0x0002 : allocate memory and store array content in it
              (the array is no more used)
    !0x0002 : return a space limitation error
   This flag is very useful to optimize code. When we know in
   most cases our code will need 80 bytes, we use an array
   of 80 bytes. In the rare cases where it is not sufficient,
   an allocated pointer is created. Like this for most
   frequently encountered cases, there is no need to allocate.
   Once allocated, it works like if it was allocated from beginning.
   Once allocated, the external array is no more used.
   Once allocated, flag NETWIB_BUF_FLAGS_ALLOC is automatically
   set.
   If array size is greater than 2k, it's not really advantageous
   to use this flag, because copying 2k needs almost the same time
   as a malloc and free.
   This flag defaults to false. It has to be explicitly set
   by user.
 */
#define NETWIB_BUF_FLAGS_CANALLOC 0x00000002u

/* If functions are :
     0x0004 : allowed to slide data (shrunk space between First
              and Begin), when there is no sufficient space
              between End and Last for appending
    !0x0004 : not allowed to slide
   This flag defaults to false. It has to be explicitly set
   by user.
*/
#define NETWIB_BUF_FLAGS_CANSLIDE 0x00000004u

/* currently unused */
#define NETWIB_BUF_FLAGS_UNUSED 0xFFFFFFF8u

/*-------------------------------------------------------------*/
/***************************************************************
 * Type netwib_bufext is exactly the same as netwib_buf. It    *
 * permits to easily determine which kind of buffer is needed  *
 * by a function :                                             *
 *  - Functions having an output parameter of type netwib_buf  *
 *    must be called with the buffer previously initialized :  *
 *    they will append data to it                              *
 *  - Functions having an output parameter of type netwib_bufext*
 *    will initialize it.                                      *
 * Example :                                                   *
 *  An IP4 packet might contain an IP4 option. There is no     *
 *  need to allocate/copy data for this option, because it is  *
 *  simply contained in the input packet (at offset            *
 *  20==sizeof(ip4hdr)). So in this case a netwib_bufext is    *
 *  used.                                                      *
 ***************************************************************/
typedef netwib_buf netwib_bufext;

/*-------------------------------------------------------------*/
/* Name : netwib_buf_init_malloc
   Description :
     Initialize a buf. Its memory dynamically grows.
   Input parameter(s) :
     allocsize : allocated size. If 0, a
                 default value is used.
   Input/output parameter(s) :
   Output parameter(s) :
     *pbuf : netwib_buf initialized
   Normal return values :
     NETWIB_ERR_OK : ok
*/
netwib_err netwib_buf_init_malloc(netwib_uint32 allocs,
                                  netwib_buf *pbuf);
#define netwib_buf_init_mallocdefault(pbuf) netwib_buf_init_malloc(0,pbuf)

/*-------------------------------------------------------------*/
/* Name : netwib_buf_init_ext_array
   Description :
     Initialize a buf. Its memory corresponds to an external
     fixed size array.
   Input parameter(s) :
     arrayptr : external array
     arraysize : external array size
     beginoffset : offset of begin in this array
     endoffset : offset of end in this array
   Input/output parameter(s) :
   Output parameter(s) :
     *pbuf : netwib_bufext initialized
   Normal return values :
     NETWIB_ERR_OK : ok
*/
netwib_err netwib_buf_init_ext_array(netwib_ptr arrayptr,
                                     netwib_uint32 arraysize,
                                     netwib_uint32 beginoffset,
                                     netwib_uint32 endoffset,
                                     netwib_bufext *pbuf);
#define netwib_buf_init_ext_arrayempty(arrayptr,arraysize,pbuf) netwib_buf_init_ext_array(arrayptr,arraysize,0,0,pbuf)
#define netwib_buf_init_ext_arrayfilled(arrayptr,arraysize,pbuf) netwib_buf_init_ext_array(arrayptr,arraysize,0,arraysize,pbuf)
/* This one permits to easily use netwib_buf_ref_string because
   there is room left for the '\0' */
#define netwib_buf_init_ext_datafilled(dataptr,datasize,pbuf) netwib_buf_init_ext_array(dataptr,datasize+1,0,datasize,pbuf)
/* This one creates pbuf which refers data from pbufin */
#define netwib_buf_init_ext_buf(pbufin,pbuf) netwib_buf_init_ext_arrayfilled(netwib__buf_ref_data_ptr(pbufin),netwib__buf_ref_data_size(pbufin),pbuf)
/* A buffer containing no data */
#define netwib_buf_init_ext_empty(pbuf) netwib_buf_init_ext_array(NULL,0,0,0,pbuf)

/*-------------------------------------------------------------*/
/* Name : netwib_buf_init_ext_text
   Description :
     Initialize a buf. Its memory corresponds to an external
     preset string.
   Input parameter(s) :
     str : external string
   Input/output parameter(s) :
   Output parameter(s) :
     *pbuf : netwib_bufext initialized
   Normal return values :
     NETWIB_ERR_OK : ok
*/
netwib_err netwib_buf_init_ext_text(netwib_conststring str,
                                    netwib_bufext *pbuf);

/*-------------------------------------------------------------*/
/* Name : netwib_buf_shift
   Description :
     Shift data in a buf.
   Input parameter(s) :
     offset : offset
     trunc : truncate on begin/end edges (otherwise, truncate
             only on first/end edges)
   Input/output parameter(s) :
     *pbuf : netwib_buf updated
   Output parameter(s) :
   Normal return values :
     NETWIB_ERR_OK : ok
   Examples :
     buf contains         "   data  "
     shift(buf,-1,0) =>   "  data   "
     shift(buf,-1,1) =>   "   ata   " (d is truncated)
     shift(buf,+1,0) =>   "    data "
     shift(buf,+4,0) =>   "       data" (if buffer is malloced)
     shift(buf,+4,0) =>   "       da" (if buffer is external)
     shift(buf,+1,1) =>   "    dat  " (a is truncated)
   Note :
     Parameter canslide has no effect on this function (this is
     logical).
*/
netwib_err netwib_buf_shift(netwib_buf *pbuf,
                            netwib_int32 offset,
                            netwib_bool trunc);

/*-------------------------------------------------------------*/
/* Name : netwib_buf_append_xyz
   Description :
     Add data to a buf.
   Input parameter(s) :
     data : data to add
     datasize : size of data to add
     str : string to add
     c : character to add
   Input/output parameter(s) :
     *pbuf : netwib_buf updated
   Output parameter(s) :
   Normal return values :
     NETWIB_ERR_OK : ok
*/
netwib_err netwib_buf_append_data(netwib_constdata data,
                                  netwib_uint32 datasize,
                                  netwib_buf *pbuf);
netwib_err netwib_buf_append_text(netwib_conststring str,
                                  netwib_buf *pbuf);
netwib_err netwib_buf_append_buf(netwib_constbuf *pbuftoappend,
                                 netwib_buf *pbuf);
netwib_err netwib_buf_append_byte(netwib_byte b,
                                  netwib_buf *pbuf);

/*-------------------------------------------------------------*/
/* Name : netwib_buf_prepend_buf
   Description :
     Prepend data to a buf.
   Input parameter(s) :
   Input/output parameter(s) :
     *pbuf : netwib_buf updated
   Output parameter(s) :
   Normal return values :
     NETWIB_ERR_OK : ok
   Note :
     Parameter canslide has no effect on this function (this is
     logical).
*/
netwib_err netwib_buf_prepend_buf(netwib_constbuf *pbuftoprepend,
                                  netwib_buf *pbuf);

/*-------------------------------------------------------------*/
/* Name : netwib_buf_ref_string
   Description :
     Get pointers to data stored in buf (between begin and end).
     If buffer internal storage does not end with '\0',
     a new one is added. So, we can have NETWIB_ERR_OKDATANOSPACE
     if there is no room for the '\0'.
   Input parameter(s) :
     *pbuf : buffer
   Input/output parameter(s) :
   Output parameter(s) :
     *pstr : pointer to start of string
   Normal return values :
     NETWIB_ERR_OK : ok
     NETWIB_ERR_OKDATANOSPACE : no room for the '\0'
*/
netwib_err netwib_buf_ref_string(netwib_constbuf *pbuf,
                                 netwib_string *pstr);

/*-------------------------------------------------------------*/
/* Name : netwib_buf_wantspace
   Description :
     Request space in a buffer (from end to last).
     When buffer is initialized as malloced memory, it is
     possible to obtain unlimited space. Otherwise, we cannot
     obtain more space than array size (unless flag
     NETWIB_BUF_FLAGS_CANALLOC is set).
   Input parameter(s) :
     wantedspace : wanted space
   Input/output parameter(s) :
     *pbuf : buffer
   Output parameter(s) :
     *pdata : pointer to end (endoffset)
   Normal return values :
     NETWIB_ERR_OK : ok
     NETWIB_ERR_OKDATANOSPACE : there is less than wantedspace
*/
netwib_err netwib_buf_wantspace(netwib_buf *pbuf,
                                netwib_uint32 wantedspace,
                                netwib_data *pdata);

/*-------------------------------------------------------------*/
/* Name : netwib_buf_wishspace
   Description :
     Request space in a buffer (from end to last).
     When buffer is initialized as malloced memory, it is
     possible to obtain unlimited space. Otherwise, we cannot
     obtain more space than array size (unless flag
     NETWIB_BUF_FLAGS_CANALLOC is set).
   Input parameter(s) :
     wantedspace : wanted space
   Input/output parameter(s) :
     *pbuf : buffer
   Output parameter(s) :
     *pdata : pointer to end (endoffset)
     *pobtainedspace : obtained space (from end to last)
   Normal return values :
     NETWIB_ERR_OK : ok
*/
netwib_err netwib_buf_wishspace(netwib_buf *pbuf,
                                netwib_uint32 wantedspace,
                                netwib_data *pdata,
                                netwib_uint32 *pobtainedspace);

/*-------------------------------------------------------------*/
/* Name : netwib_buf_cmp
   Description :
     Compare two netwib_buf.
   Input parameter(s) :
     *pbuf1 : netwib_buf to compare with buf2
     *pbuf2 : netwib_buf to compare with buf1
   Input/output parameter(s) :
   Output parameter(s) :
     *pcmp :
       NETWIB_CMP_LT : buf1<buf2
       NETWIB_CMP_EQ : if buf1 and buf2 are equal
       NETWIB_CMP_GT : buf1>buf2
   Normal return values :
     NETWIB_ERR_OK : ok
*/
netwib_err netwib_buf_cmp(netwib_constbuf *pbuf1,
                          netwib_constbuf *pbuf2,
                          netwib_cmp *pcmp);

/*-------------------------------------------------------------*/
/* Name : netwib_buf_close
   Description :
     Close buf, eventually freeing data it contains.
   Input parameter(s) :
   Input/output parameter(s) :
     *pbuf : buffer closed
   Output parameter(s) :
   Normal return values :
     NETWIB_ERR_OK : ok
   Note :
     This function is only needed for a buffer initialized
     with netwib_buf_init_malloc, or if flag
     NETWIB_BUF_FLAGS_CANALLOC is set.
*/
netwib_err netwib_buf_close(netwib_buf *pbuf);

/*-------------------------------------------------------------*/
/* Frequently needed defines */
#define netwib__buf_reinit(pbuf) (pbuf)->beginoffset = 0; (pbuf)->endoffset = 0;
#define netwib__buf_erase(pbuf) (pbuf)->endoffset = (pbuf)->beginoffset;
#define netwib__buf_ref_data_ptr(pbuf) ((pbuf)->totalptr + (pbuf)->beginoffset)
#define netwib__buf_ref_data_size(pbuf) ((pbuf)->endoffset -(pbuf)->beginoffset)
#define netwib__buf_ref_data_sizenull(pbuf) ((pbuf)!=NULL?netwib__buf_ref_data_size(pbuf):0)





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