Adds one component of the option content to the options header.
    Format
      #include  <in6.h>
      int inet6_opt_set_val  ( void *databuf, size_t offset, void
                             *val int vallen );

1  –  Arguments

 databuf
    Points to a buffer that contains an extension header. This is a
    pointer returned by a call to inet6_opt_append().
 offset
    Specifies the location in the data portion of the option into
    which to insert the data. You can access the first byte after the
    option type and length by specifying the offset of 0 (zero).
 val
    Points to the data to be inserted.
 vallen
    Specifies the length of the data, in bytes, to be inserted.

2  –  Description

    This function copies data items at the location val into a data
    buffer databuf beginning at offset. In addition, it returns the
    offset for the next data field to assist you in composing content
    that has multiple fields.
    Make sure that each field is aligned on its natural boundaries.

3  –  Return Values

    x                  Upon successful completion, the inet6_opt_set_
                       val() function returns the offset for the next
                       field in the data buffer.
    -1                 Failure