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Resolver: fixes in A processing.

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Verify that class of RR is "IN".
Verify that RR data length is exactly four octets.
Correctly shift to the next RR if RR type is unknown.
This commit is contained in:
Ruslan Ermilov 2013-12-06 14:30:27 +04:00
parent f3a271f3fd
commit f57350cd86
1 changed files with 25 additions and 14 deletions
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39
src/core/ngx_resolver.c
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@ -1179,7 +1179,7 @@ ngx_resolver_process_a(ngx_resolver_t *r, u_char *buf, size_t last,
uint32_t hash;
in_addr_t addr, *addrs;
ngx_str_t name;
ngx_uint_t type, qident, naddrs, a, i, n, start;
ngx_uint_t type, class, qident, naddrs, a, i, n, start;
ngx_resolver_an_t *an;
ngx_resolver_ctx_t *ctx, *next;
ngx_resolver_node_t *rn;
@ -1202,6 +1202,7 @@ ngx_resolver_process_a(ngx_resolver_t *r, u_char *buf, size_t last,
if (rn == NULL || rn->query == NULL) {
ngx_log_error(r->log_level, r->log, 0,
"unexpected response for %V", &name);
ngx_resolver_free(r, name.data);
goto failed;
}
@ -1211,6 +1212,7 @@ ngx_resolver_process_a(ngx_resolver_t *r, u_char *buf, size_t last,
ngx_log_error(r->log_level, r->log, 0,
"wrong ident %ui response for %V, expect %ui",
ident, &name, qident);
ngx_resolver_free(r, name.data);
goto failed;
}
@ -1287,21 +1289,33 @@ ngx_resolver_process_a(ngx_resolver_t *r, u_char *buf, size_t last,
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;
}
i += sizeof(ngx_resolver_an_t);
switch (type) {
case NGX_RESOLVE_A:
i += sizeof(ngx_resolver_an_t);
if (len != 4) {
err = "invalid A record in DNS response";
goto invalid;
}
if (i + len > last) {
if (i + 4 > last) {
goto short_response;
}
@ -1310,21 +1324,16 @@ ngx_resolver_process_a(ngx_resolver_t *r, u_char *buf, size_t last,
naddrs++;
i += len;
break;
case NGX_RESOLVE_CNAME:
cname = &buf[i] + sizeof(ngx_resolver_an_t);
i += sizeof(ngx_resolver_an_t) + len;
cname = &buf[i];
break;
case NGX_RESOLVE_DNAME:
i += sizeof(ngx_resolver_an_t) + len;
break;
default:
@ -1332,6 +1341,8 @@ ngx_resolver_process_a(ngx_resolver_t *r, u_char *buf, size_t last,
ngx_log_error(r->log_level, r->log, 0,
"unexpected RR type %ui", type);
}
i += len;
}
ngx_log_debug3(NGX_LOG_DEBUG_CORE, r->log, 0,
@ -1347,7 +1358,7 @@ ngx_resolver_process_a(ngx_resolver_t *r, u_char *buf, size_t last,
addrs = ngx_resolver_alloc(r, naddrs * sizeof(in_addr_t));
if (addrs == NULL) {
return;
goto failed;
}
n = 0;
@ -1395,7 +1406,7 @@ ngx_resolver_process_a(ngx_resolver_t *r, u_char *buf, size_t last,
addrs = ngx_resolver_dup(r, rn->u.addrs,
naddrs * sizeof(in_addr_t));
if (addrs == NULL) {
return;
goto failed;
}
}
@ -1439,7 +1450,7 @@ ngx_resolver_process_a(ngx_resolver_t *r, u_char *buf, size_t last,
/* CNAME only */
if (ngx_resolver_copy(r, &name, buf, cname, buf + last) != NGX_OK) {
return;
goto failed;
}
ngx_log_debug1(NGX_LOG_DEBUG_CORE, r->log, 0,
@ -1467,6 +1478,8 @@ ngx_resolver_process_a(ngx_resolver_t *r, u_char *buf, size_t last,
ngx_resolver_free(r, rn->query);
rn->query = NULL;
/* unlock name mutex */
return;
}
@ -1490,8 +1503,6 @@ failed:
/* unlock name mutex */
ngx_resolver_free(r, name.data);
return;
}