int silc_buffer_strformat(SilcBuffer dst, ...);

    Formats a buffer from variable argument list of strings.  Each
    string must be NULL-terminated and the variable argument list must
    be end with SILC_STRFMT_END argument.  This allows that a string in
    the list can be NULL, in which case it is skipped.  This automatically
    allocates the space for the buffer data but `dst' must be already
    allocated by the caller.

    ret = silc_buffer_strformat(buffer, "foo", "bar", SILC_STRFMT_END);
    if (ret < 0)
      error;