From 32dc912febbf3960c47a0ebfd387977b2c78656b Mon Sep 17 00:00:00 2001 From: ume Date: Sun, 10 Jun 2001 20:25:24 +0000 Subject: [PATCH] Implement EDNS0 support, as EDNS0 support will be made mandatory for IPv6 transport-ready resolvers/DNS servers. Need careful configuration when enable it. (default config is not affected). See manpage for details. XXX visible symbol __res_opt() is added, however, it is not supposed to be called from outside, libc minor is not bumped. Obtained from: KAME/NetBSD --- include/arpa/nameser.h | 1 + include/arpa/nameser_compat.h | 1 + include/resolv.h | 4 ++++ lib/libc/net/getaddrinfo.c | 6 +++++- lib/libc/net/res_debug.c | 4 ++++ lib/libc/net/res_init.c | 2 ++ lib/libc/net/res_mkquery.c | 37 +++++++++++++++++++++++++++++++++++ lib/libc/net/res_query.c | 2 ++ lib/libc/net/resolver.3 | 15 +++++++++++++- share/examples/IPv6/USAGE | 34 ++++++++++++++++++++++++++++++++ 10 files changed, 104 insertions(+), 2 deletions(-) diff --git a/include/arpa/nameser.h b/include/arpa/nameser.h index 3e09c912ddac..343e6416a402 100644 --- a/include/arpa/nameser.h +++ b/include/arpa/nameser.h @@ -273,6 +273,7 @@ typedef enum __ns_type { ns_t_srv = 33, /* Server Selection. */ ns_t_atma = 34, /* ATM Address */ ns_t_naptr = 35, /* Naming Authority PoinTeR */ + ns_t_opt = 41, /* OPT pseudo-RR, RFC2761 */ /* Query type values which do not appear in resource records. */ ns_t_ixfr = 251, /* Incremental zone transfer. */ ns_t_axfr = 252, /* Transfer zone of authority. */ diff --git a/include/arpa/nameser_compat.h b/include/arpa/nameser_compat.h index 850fb8a0890d..232179730fe5 100644 --- a/include/arpa/nameser_compat.h +++ b/include/arpa/nameser_compat.h @@ -173,6 +173,7 @@ typedef struct { #define T_SRV ns_t_srv #define T_ATMA ns_t_atma #define T_NAPTR ns_t_naptr +#define T_OPT ns_t_opt #define T_IXFR ns_t_ixfr #define T_AXFR ns_t_axfr #define T_MAILB ns_t_mailb diff --git a/include/resolv.h b/include/resolv.h index 4a0cf7470aba..a076c7e0fdd9 100644 --- a/include/resolv.h +++ b/include/resolv.h @@ -150,6 +150,8 @@ struct __res_state_ext { #define RES_NOALIASES 0x00001000 /* shuts off HOSTALIASES feature */ #define RES_USE_INET6 0x00002000 /* use/map IPv6 in gethostbyname() */ #define RES_NOTLDQUERY 0x00004000 /* Don't query TLD names */ +/* KAME extensions: use higher bit to avoid conflict with ISC use */ +#define RES_USE_EDNS0 0x40000000 /* use EDNS0 */ #define RES_DEFAULT (RES_RECURSE | RES_DEFNAMES | RES_DNSRCH) @@ -249,6 +251,7 @@ extern const struct res_sym __p_type_syms[]; #define res_nameinquery __res_nameinquery #define res_queriesmatch __res_queriesmatch #define res_close __res_close +#define res_opt __res_opt #define res_mkupdate __res_mkupdate #define res_mkupdrec __res_mkupdrec #define res_freeupdrec __res_freeupdrec @@ -303,6 +306,7 @@ int res_nameinquery __P((const char *, int, int, int res_queriesmatch __P((const u_char *, const u_char *, const u_char *, const u_char *)); void res_close __P((void)); +int res_opt __P((int, u_char *, int, int)); const char * p_section __P((int, int)); /* XXX The following depend on the ns_updrec typedef in arpa/nameser.h */ #ifdef _ARPA_NAMESER_H_ diff --git a/lib/libc/net/getaddrinfo.c b/lib/libc/net/getaddrinfo.c index c54b2521d4fc..8ff92c2024f1 100644 --- a/lib/libc/net/getaddrinfo.c +++ b/lib/libc/net/getaddrinfo.c @@ -79,7 +79,6 @@ * - other KAME platforms already nuked FAITH ($GAI), but as FreeBSD * 4.0-RELEASE supplies it, we still have the code here. * - AI_ADDRCONFIG support is supplied - * - EDNS0 support is not available due to resolver differences * - some of FreeBSD style (#define tabify and others) * - classful IPv4 numeric (127.1) is allowed. */ @@ -101,6 +100,9 @@ #include #include #include +#ifdef DEBUG +#include +#endif #include #include @@ -1718,6 +1720,8 @@ res_queryN(name, target) n = res_mkquery(QUERY, name, class, type, NULL, 0, NULL, buf, sizeof(buf)); + if (n > 0 && (_res.options & RES_USE_EDNS0) != 0) + n = res_opt(n, buf, sizeof(buf), anslen); if (n <= 0) { #ifdef DEBUG if (_res.options & RES_DEBUG) diff --git a/lib/libc/net/res_debug.c b/lib/libc/net/res_debug.c index 16033f202ce0..b6ed1f539668 100644 --- a/lib/libc/net/res_debug.c +++ b/lib/libc/net/res_debug.c @@ -519,6 +519,10 @@ p_option(u_long option) { case RES_DNSRCH: return "dnsrch"; case RES_INSECURE1: return "insecure1"; case RES_INSECURE2: return "insecure2"; + case RES_NOALIASES: return "noaliases"; + case RES_USE_INET6: return "inet6"; + case RES_NOTLDQUERY: return "no-tld-query"; + case RES_USE_EDNS0: return "edns0"; default: sprintf(nbuf, "?0x%lx?", (u_long)option); return (nbuf); } diff --git a/lib/libc/net/res_init.c b/lib/libc/net/res_init.c index 9203b695459a..035dd05b3563 100644 --- a/lib/libc/net/res_init.c +++ b/lib/libc/net/res_init.c @@ -532,6 +532,8 @@ res_setoptions(options, source) _res.options |= RES_USE_INET6; } else if (!strncmp(cp, "no_tld_query", sizeof("no_tld_query") - 1)) { _res.options |= RES_NOTLDQUERY; + } else if (!strncmp(cp, "edns0", sizeof("edns0") - 1)) { + _res.options |= RES_USE_EDNS0; } else { /* XXX - print a warning here? */ } diff --git a/lib/libc/net/res_mkquery.c b/lib/libc/net/res_mkquery.c index 5ac662bd1432..6cbd37394b92 100644 --- a/lib/libc/net/res_mkquery.c +++ b/lib/libc/net/res_mkquery.c @@ -204,3 +204,40 @@ res_mkquery(op, dname, class, type, data, datalen, newrr_in, buf, buflen) */ #undef res_mkquery __weak_reference(__res_mkquery, res_mkquery); + +/* attach OPT pseudo-RR, as documented in RFC2671 (EDNS0). */ +int +res_opt(n0, buf, buflen, anslen) + int n0; + u_char *buf; /* buffer to put query */ + int buflen; /* size of buffer */ + int anslen; /* answer buffer length */ +{ + register HEADER *hp; + register u_char *cp; + + hp = (HEADER *) buf; + cp = buf + n0; + buflen -= n0; + + if (buflen < 1 + RRFIXEDSZ) + return -1; + + *cp++ = 0; /* "." */ + buflen--; + + __putshort(T_OPT, cp); /* TYPE */ + cp += INT16SZ; + __putshort(anslen & 0xffff, cp); /* CLASS = UDP payload size */ + cp += INT16SZ; + *cp++ = NOERROR; /* extended RCODE */ + *cp++ = 0; /* EDNS version */ + __putshort(0, cp); /* MBZ */ + cp += INT16SZ; + __putshort(0, cp); /* RDLEN */ + cp += INT16SZ; + hp->arcount = htons(ntohs(hp->arcount) + 1); + buflen -= RRFIXEDSZ; + + return cp - buf; +} diff --git a/lib/libc/net/res_query.c b/lib/libc/net/res_query.c index 0ee2ad2504ab..8a94a4205f72 100644 --- a/lib/libc/net/res_query.c +++ b/lib/libc/net/res_query.c @@ -129,6 +129,8 @@ res_query(name, class, type, answer, anslen) n = res_mkquery(QUERY, name, class, type, NULL, 0, NULL, buf, sizeof(buf)); + if (n > 0 && (_res.options & RES_USE_EDNS0) != 0) + n = res_opt(n, buf, sizeof(buf), anslen); if (n <= 0) { #ifdef DEBUG if (_res.options & RES_DEBUG) diff --git a/lib/libc/net/resolver.3 b/lib/libc/net/resolver.3 index 1fb97f568be3..e06a5fd7c6ac 100644 --- a/lib/libc/net/resolver.3 +++ b/lib/libc/net/resolver.3 @@ -119,7 +119,7 @@ are defined in and are as follows. Options are stored as a simple bit mask containing the bitwise ``or'' of the options enabled. -.Bl -tag -width RES_DEFNAMES +.Bl -tag -width RES_USE_INET6 .It Dv RES_INIT True if the initial name server address and default domain name are initialized (i.e., @@ -176,6 +176,19 @@ This option is enabled by default. This option turns off the user level aliasing feature controlled by the .Dq Ev HOSTALIASES environment variable. Network daemons should set this option. +.It Dv RES_USE_INET6 +Enables support for IPv6-only applications. +This causes IPv4 addresses to be returned as an IPv4 mapped address. +For example, 10.1.1.1 will be returned as ::ffff:10.1.1.1. +The option is meaningful with certain kernel configuration only. +.It Dv RES_USE_EDNS0 +Enables support for OPT pseudo-RR for EDNS0 extension. +With the option, resolver code will attach OPT pseudo-RR into DNS queries, +to inform of our receive buffer size. +The option will allow DNS servers to take advantage of non-default receive +buffer size, and to send larger replies. +DNS query packets with EDNS0 extension is not compatible with +non-EDNS0 DNS servers. .El .Pp The diff --git a/share/examples/IPv6/USAGE b/share/examples/IPv6/USAGE index f9122c2725d4..5a02037569f4 100644 --- a/share/examples/IPv6/USAGE +++ b/share/examples/IPv6/USAGE @@ -626,4 +626,38 @@ Configuration at Host-A: -E rc5-cbc "kamekame" -A hmac-md5 "this is the test" ; +<<>> + +EDNS0 is defined in RFC2671. With EDNS0, the resolver library can tell DNS +server of its receiving buffer size, and permit DNS server to transmit large +reply packet. EDNS0 is necessary to take advantage of larger minimum MTU +in IPv6. KAME libinet6 includes resolver side support for EDNS0. +Server side support for EDNS0 is included in ISC BIND9. + + query packet with EDNS0 + tells receive buffer size +KAME box -----------------------------> BIND9 DNS server +KAME box <----------------------------- BIND9 DNS server + can transmit jumbo reply, since DNS server + knows receive buffer size of KAME box + +How to play with it: +- prepare KAME box and BIND9 DNS server (can be a same node) +- add the following into /etc/resolv.conf on KAME box: + options edns0 <--- enables EDNS0 + nameserver +- run applications compiled with libinet6 (like /usr/local/v6/bin/telnet), + see EDNS0 packet fly on the wire by tcpdump or some other method. + +Caveats: +- BIND 4/8 DNS server will choke with EDNS0 packet, so you must not + turn the option on if you have BIND 4/8 DNS server. If you enable + "options edns0" against BIND 4/8 DNS server, you will never be able + to resolve names. +- If you use IPv6 UDP as DNS transport, path MTU discovery may + affect the traffic. KAME box tries to fragment packet to 1280 + bytes, however, BIND9 may not. +- Some of our platforms do not use our extended resolver code in libinet6. + See COVERAGE for detail. +