details: http://hg.nginx.org/nginx/rev/33c4d319f08f branches: changeset: 6371:33c4d319f08f user: Ruslan Ermilov <r...@nginx.com> date: Thu Dec 17 17:21:16 2015 +0300 description: Resolver: improved PTR response processing.
The previous code only parsed the first answer, without checking its type, and required a compressed RR name. The new code checks the RR type, supports responses with multiple answers, and doesn't require the RR name to be compressed. This has a side effect in limited support of CNAME. If a response includes both CNAME and PTR RRs, like when recursion is enabled on the server, PTR RR is handled. Full CNAME support in PTR response is not implemented in this change. diffstat: src/core/ngx_resolver.c | 118 +++++++++++++++++++++++++++++++++-------------- 1 files changed, 82 insertions(+), 36 deletions(-) diffs (138 lines): diff -r 8c8739bdd3f1 -r 33c4d319f08f src/core/ngx_resolver.c --- a/src/core/ngx_resolver.c Thu Dec 17 17:21:12 2015 +0300 +++ b/src/core/ngx_resolver.c Thu Dec 17 17:21:16 2015 +0300 @@ -2401,7 +2401,7 @@ ngx_resolver_process_ptr(ngx_resolver_t int32_t ttl; ngx_int_t octet; ngx_str_t name; - ngx_uint_t i, mask, qident, class; + ngx_uint_t mask, type, class, qident, a, i, start; ngx_queue_t *expire_queue; ngx_rbtree_t *tree; ngx_resolver_an_t *an; @@ -2554,44 +2554,90 @@ valid: i += sizeof(ngx_resolver_qs_t); - if (i + 2 + sizeof(ngx_resolver_an_t) >= n) { + for (a = 0; a < nan; a++) { + + start = i; + + while (i < n) { + + if (buf[i] & 0xc0) { + i += 2; + goto found; + } + + if (buf[i] == 0) { + i++; + goto test_length; + } + + i += 1 + buf[i]; + } + goto short_response; + + test_length: + + if (i - start < 2) { + err = "invalid name in DNS response"; + goto invalid; + } + + found: + + if (i + sizeof(ngx_resolver_an_t) >= n) { + goto short_response; + } + + an = (ngx_resolver_an_t *) &buf[i]; + + type = (an->type_hi << 8) + an->type_lo; + class = (an->class_hi << 8) + an->class_lo; + len = (an->len_hi << 8) + an->len_lo; + ttl = (an->ttl[0] << 24) + (an->ttl[1] << 16) + + (an->ttl[2] << 8) + (an->ttl[3]); + + if (class != 1) { + ngx_log_error(r->log_level, r->log, 0, + "unexpected RR class %ui", class); + goto failed; + } + + if (ttl < 0) { + ttl = 0; + } + + ngx_log_debug3(NGX_LOG_DEBUG_CORE, r->log, 0, + "resolver qt:%ui cl:%ui len:%uz", + type, class, len); + + i += sizeof(ngx_resolver_an_t); + + switch (type) { + + case NGX_RESOLVE_PTR: + + goto ptr; + + case NGX_RESOLVE_CNAME: + + break; + + default: + + ngx_log_error(r->log_level, r->log, 0, + "unexpected RR type %ui", type); + } + + i += len; } - /* compression pointer to *.arpa */ - - if (buf[i] != 0xc0 || buf[i + 1] != sizeof(ngx_resolver_hdr_t)) { - err = "invalid in-addr.arpa or ip6.arpa name in DNS response"; - goto invalid; - } - - an = (ngx_resolver_an_t *) &buf[i + 2]; - - class = (an->class_hi << 8) + an->class_lo; - len = (an->len_hi << 8) + an->len_lo; - ttl = (an->ttl[0] << 24) + (an->ttl[1] << 16) - + (an->ttl[2] << 8) + (an->ttl[3]); - - if (class != 1) { - ngx_log_error(r->log_level, r->log, 0, - "unexpected RR class %ui", class); - goto failed; - } - - if (ttl < 0) { - ttl = 0; - } - - ngx_log_debug3(NGX_LOG_DEBUG_CORE, r->log, 0, - "resolver qt:%ui cl:%ui len:%uz", - (an->type_hi << 8) + an->type_lo, - class, len); - - i += 2 + sizeof(ngx_resolver_an_t); - - if (i + len > n) { - goto short_response; - } + /* unlock addr mutex */ + + ngx_log_error(r->log_level, r->log, 0, + "no PTR type in DNS response"); + return; + +ptr: if (ngx_resolver_copy(r, &name, buf, buf + i, buf + n) != NGX_OK) { goto failed; _______________________________________________ nginx-devel mailing list nginx-devel@nginx.org http://mailman.nginx.org/mailman/listinfo/nginx-devel