resolv: Deprecate legacy interfaces in libresolv

Debugging interfaces: p_*, fp_*, and sym_* could conceivably be
used to produce debug out, but these functions have not been
updated to parse more resource records, so they are not very useful
today.  Likewise for ns_sprintrr and ns_sprintrrf.  ns_format_ttl and
ns_parse_ttl are related to these.

Internal implementation details: res_isourserver is probably only
useful in the implementation of a stub resolver, and so is
res_nameinquery.

Unclear semantics and bad performance: ns_samedomain, ns_subdomain,
ns_makecanon, ns_samename do textual converions & copies instead of
checking equivalence of the wire format.

inet_neta cannot handle IPv6 addresses.

res_hostalias has been superseded by getaddrinfo with AI_CANONNAME.
hostalias is not thread-safe.

Some functions have int as size arguments instead of size_t, so they
do not follow current coding practices.  However, dn_expand and
b64_ntop are somewhat widely used (to name just two examples), so
deprecating them seems problematic.

Reviewed-by: Carlos O'Donell <carlos@systemhalted.org>

1 files changed, 14 insertions, 0 deletions

diff --git a/NEWS b/NEWS
index 13ffe627da..4df348cce5 100644
--- a/NEWS
+++ b/NEWS
@@ -93,6 +93,20 @@ Deprecated and removed features, and other changes affecting compatibility:
 * The function pthread_yield has been deprecated; programs should use
   the equivalent standard function sched_yield instead.
 
+* The function inet_neta declared in <arpa/inet.h> has been deprecated.
+
+* Various rarely-used functions declared in <resolv.h> and
+  <arpa/nameser.h> have been deprecated.  Applications are encouraged to
+  use dedicated DNS processing libraries if applicable.  For <resolv.h>,
+  this affects the functions dn_count_labels, fp_nquery, fp_query,
+  fp_resstat, hostalias, loc_aton, loc_ntoa, p_cdname, p_cdnname,
+  p_class, p_fqname, p_fqnname, p_option, p_query, p_rcode, p_time,
+  p_type, putlong, putshort, res_hostalias, res_isourserver,
+  res_nameinquery, res_queriesmatch, res_randomid, sym_ntop, sym_ntos,
+  sym_ston.  For <arpa/nameser.h>, the functions ns_datetosecs,
+  ns_format_ttl, ns_makecanon, ns_parse_ttl, ns_samedomain, ns_samename,
+  ns_sprintrr, ns_sprintrrf, ns_subdomain have been deprecated.
+
 * The pthread cancellation handler is now installed with SA_RESTART and
   pthread_cancel will always send the internal SIGCANCEL on a cancellation
   request.  It should not be visible to application since the cancellation