Returns the number of bytes needed for an empty extension header.
The inet6_opt_init subroutine returns the number of bytes needed for the empty extension header (that is, a header without any options).
| Item | Description |
|---|---|
| extbuf | Specifies NULL for an empty header. If extbuf is not NULL, it initializes the extension header to have the correct length field. |
| extlen | Specifies the size of the extension header. The value of extlen must be a positive value that is a multiple of 8. |
| Item | Description |
|---|---|
| -1 | The value of extlen is not a positive (non-zero) multiple of 8. |
| integer value | Number of bytes needed for an empty extension header. |