Google Git
Sign in
nginx / nginx / 1b902022e4e8344fa1bebe63e68fbf5a073482d8 / . / src / core / ngx_resolver.c
blob: 6d129e56aff9bbe64f34125d6045f8c0ec6d485f [file] [log] [blame]
/*
* Copyright (C) Igor Sysoev
* Copyright (C) Nginx, Inc.
*/
#include <ngx_config.h>
#include <ngx_core.h>
#include <ngx_event.h>
#define NGX_RESOLVER_UDP_SIZE 4096
#define NGX_RESOLVER_TCP_RSIZE (2 + 65535)
#define NGX_RESOLVER_TCP_WSIZE 8192
typedef struct {
u_char ident_hi;
u_char ident_lo;
u_char flags_hi;
u_char flags_lo;
u_char nqs_hi;
u_char nqs_lo;
u_char nan_hi;
u_char nan_lo;
u_char nns_hi;
u_char nns_lo;
u_char nar_hi;
u_char nar_lo;
} ngx_resolver_hdr_t;
typedef struct {
u_char type_hi;
u_char type_lo;
u_char class_hi;
u_char class_lo;
} ngx_resolver_qs_t;
typedef struct {
u_char type_hi;
u_char type_lo;
u_char class_hi;
u_char class_lo;
u_char ttl[4];
u_char len_hi;
u_char len_lo;
} ngx_resolver_an_t;
#define ngx_resolver_node(n) ngx_rbtree_data(n, ngx_resolver_node_t, node)
static ngx_int_t ngx_udp_connect(ngx_resolver_connection_t *rec);
static ngx_int_t ngx_tcp_connect(ngx_resolver_connection_t *rec);
static void ngx_resolver_cleanup(void *data);
static void ngx_resolver_cleanup_tree(ngx_resolver_t *r, ngx_rbtree_t *tree);
static ngx_int_t ngx_resolve_name_locked(ngx_resolver_t *r,
ngx_resolver_ctx_t *ctx, ngx_str_t *name);
static void ngx_resolver_expire(ngx_resolver_t *r, ngx_rbtree_t *tree,
ngx_queue_t *queue);
static ngx_int_t ngx_resolver_send_query(ngx_resolver_t *r,
ngx_resolver_node_t *rn);
static ngx_int_t ngx_resolver_send_udp_query(ngx_resolver_t *r,
ngx_resolver_connection_t *rec, u_char *query, u_short qlen);
static ngx_int_t ngx_resolver_send_tcp_query(ngx_resolver_t *r,
ngx_resolver_connection_t *rec, u_char *query, u_short qlen);
static ngx_int_t ngx_resolver_create_name_query(ngx_resolver_t *r,
ngx_resolver_node_t *rn, ngx_str_t *name);
static ngx_int_t ngx_resolver_create_srv_query(ngx_resolver_t *r,
ngx_resolver_node_t *rn, ngx_str_t *name);
static ngx_int_t ngx_resolver_create_addr_query(ngx_resolver_t *r,
ngx_resolver_node_t *rn, ngx_resolver_addr_t *addr);
static void ngx_resolver_resend_handler(ngx_event_t *ev);
static time_t ngx_resolver_resend(ngx_resolver_t *r, ngx_rbtree_t *tree,
ngx_queue_t *queue);
static ngx_uint_t ngx_resolver_resend_empty(ngx_resolver_t *r);
static void ngx_resolver_udp_read(ngx_event_t *rev);
static void ngx_resolver_tcp_write(ngx_event_t *wev);
static void ngx_resolver_tcp_read(ngx_event_t *rev);
static void ngx_resolver_process_response(ngx_resolver_t *r, u_char *buf,
size_t n, ngx_uint_t tcp);
static void ngx_resolver_process_a(ngx_resolver_t *r, u_char *buf, size_t n,
ngx_uint_t ident, ngx_uint_t code, ngx_uint_t qtype,
ngx_uint_t nan, ngx_uint_t trunc, ngx_uint_t ans);
static void ngx_resolver_process_srv(ngx_resolver_t *r, u_char *buf, size_t n,
ngx_uint_t ident, ngx_uint_t code, ngx_uint_t nan,
ngx_uint_t trunc, ngx_uint_t ans);
static void ngx_resolver_process_ptr(ngx_resolver_t *r, u_char *buf, size_t n,
ngx_uint_t ident, ngx_uint_t code, ngx_uint_t nan);
static ngx_resolver_node_t *ngx_resolver_lookup_name(ngx_resolver_t *r,
ngx_str_t *name, uint32_t hash);
static ngx_resolver_node_t *ngx_resolver_lookup_srv(ngx_resolver_t *r,
ngx_str_t *name, uint32_t hash);
static ngx_resolver_node_t *ngx_resolver_lookup_addr(ngx_resolver_t *r,
in_addr_t addr);
static void ngx_resolver_rbtree_insert_value(ngx_rbtree_node_t *temp,
ngx_rbtree_node_t *node, ngx_rbtree_node_t *sentinel);
static ngx_int_t ngx_resolver_copy(ngx_resolver_t *r, ngx_str_t *name,
u_char *buf, u_char *src, u_char *last);
static ngx_int_t ngx_resolver_set_timeout(ngx_resolver_t *r,
ngx_resolver_ctx_t *ctx);
static void ngx_resolver_timeout_handler(ngx_event_t *ev);
static void ngx_resolver_free_node(ngx_resolver_t *r, ngx_resolver_node_t *rn);
static void *ngx_resolver_alloc(ngx_resolver_t *r, size_t size);
static void *ngx_resolver_calloc(ngx_resolver_t *r, size_t size);
static void ngx_resolver_free(ngx_resolver_t *r, void *p);
static void ngx_resolver_free_locked(ngx_resolver_t *r, void *p);
static void *ngx_resolver_dup(ngx_resolver_t *r, void *src, size_t size);
static ngx_resolver_addr_t *ngx_resolver_export(ngx_resolver_t *r,
ngx_resolver_node_t *rn, ngx_uint_t rotate);
static void ngx_resolver_report_srv(ngx_resolver_t *r, ngx_resolver_ctx_t *ctx);
static u_char *ngx_resolver_log_error(ngx_log_t *log, u_char *buf, size_t len);
static void ngx_resolver_resolve_srv_names(ngx_resolver_ctx_t *ctx,
ngx_resolver_node_t *rn);
static void ngx_resolver_srv_names_handler(ngx_resolver_ctx_t *ctx);
static ngx_int_t ngx_resolver_cmp_srvs(const void *one, const void *two);
#if (NGX_HAVE_INET6)
static void ngx_resolver_rbtree_insert_addr6_value(ngx_rbtree_node_t *temp,
ngx_rbtree_node_t *node, ngx_rbtree_node_t *sentinel);
static ngx_resolver_node_t *ngx_resolver_lookup_addr6(ngx_resolver_t *r,
struct in6_addr *addr, uint32_t hash);
#endif
ngx_resolver_t *
ngx_resolver_create(ngx_conf_t *cf, ngx_str_t *names, ngx_uint_t n)
{
ngx_str_t s;
ngx_url_t u;
ngx_uint_t i, j;
ngx_resolver_t *r;
ngx_pool_cleanup_t *cln;
ngx_resolver_connection_t *rec;
r = ngx_pcalloc(cf->pool, sizeof(ngx_resolver_t));
if (r == NULL) {
return NULL;
}
r->event = ngx_pcalloc(cf->pool, sizeof(ngx_event_t));
if (r->event == NULL) {
return NULL;
}
cln = ngx_pool_cleanup_add(cf->pool, 0);
if (cln == NULL) {
return NULL;
}
cln->handler = ngx_resolver_cleanup;
cln->data = r;
ngx_rbtree_init(&r->name_rbtree, &r->name_sentinel,
ngx_resolver_rbtree_insert_value);
ngx_rbtree_init(&r->srv_rbtree, &r->srv_sentinel,
ngx_resolver_rbtree_insert_value);
ngx_rbtree_init(&r->addr_rbtree, &r->addr_sentinel,
ngx_rbtree_insert_value);
ngx_queue_init(&r->name_resend_queue);
ngx_queue_init(&r->srv_resend_queue);
ngx_queue_init(&r->addr_resend_queue);
ngx_queue_init(&r->name_expire_queue);
ngx_queue_init(&r->srv_expire_queue);
ngx_queue_init(&r->addr_expire_queue);
#if (NGX_HAVE_INET6)
r->ipv6 = 1;
ngx_rbtree_init(&r->addr6_rbtree, &r->addr6_sentinel,
ngx_resolver_rbtree_insert_addr6_value);
ngx_queue_init(&r->addr6_resend_queue);
ngx_queue_init(&r->addr6_expire_queue);
#endif
r->event->handler = ngx_resolver_resend_handler;
r->event->data = r;
r->event->log = &cf->cycle->new_log;
r->event->cancelable = 1;
r->ident = -1;
r->resend_timeout = 5;
r->tcp_timeout = 5;
r->expire = 30;
r->valid = 0;
r->log = &cf->cycle->new_log;
r->log_level = NGX_LOG_ERR;
if (n) {
if (ngx_array_init(&r->connections, cf->pool, n,
sizeof(ngx_resolver_connection_t))
!= NGX_OK)
{
return NULL;
}
}
for (i = 0; i < n; i++) {
if (ngx_strncmp(names[i].data, "valid=", 6) == 0) {
s.len = names[i].len - 6;
s.data = names[i].data + 6;
r->valid = ngx_parse_time(&s, 1);
if (r->valid == (time_t) NGX_ERROR) {
ngx_conf_log_error(NGX_LOG_EMERG, cf, 0,
"invalid parameter: %V", &names[i]);
return NULL;
}
continue;
}
#if (NGX_HAVE_INET6)
if (ngx_strncmp(names[i].data, "ipv6=", 5) == 0) {
if (ngx_strcmp(&names[i].data[5], "on") == 0) {
r->ipv6 = 1;
} else if (ngx_strcmp(&names[i].data[5], "off") == 0) {
r->ipv6 = 0;
} else {
ngx_conf_log_error(NGX_LOG_EMERG, cf, 0,
"invalid parameter: %V", &names[i]);
return NULL;
}
continue;
}
#endif
ngx_memzero(&u, sizeof(ngx_url_t));
u.url = names[i];
u.default_port = 53;
if (ngx_parse_url(cf->pool, &u) != NGX_OK) {
if (u.err) {
ngx_conf_log_error(NGX_LOG_EMERG, cf, 0,
"%s in resolver \"%V\"",
u.err, &u.url);
}
return NULL;
}
rec = ngx_array_push_n(&r->connections, u.naddrs);
if (rec == NULL) {
return NULL;
}
ngx_memzero(rec, u.naddrs * sizeof(ngx_resolver_connection_t));
for (j = 0; j < u.naddrs; j++) {
rec[j].sockaddr = u.addrs[j].sockaddr;
rec[j].socklen = u.addrs[j].socklen;
rec[j].server = u.addrs[j].name;
rec[j].resolver = r;
}
}
if (n && r->connections.nelts == 0) {
ngx_conf_log_error(NGX_LOG_EMERG, cf, 0, "no name servers defined");
return NULL;
}
return r;
}
static void
ngx_resolver_cleanup(void *data)
{
ngx_resolver_t *r = data;
ngx_uint_t i;
ngx_resolver_connection_t *rec;
ngx_log_debug0(NGX_LOG_DEBUG_CORE, ngx_cycle->log, 0, "cleanup resolver");
ngx_resolver_cleanup_tree(r, &r->name_rbtree);
ngx_resolver_cleanup_tree(r, &r->srv_rbtree);
ngx_resolver_cleanup_tree(r, &r->addr_rbtree);
#if (NGX_HAVE_INET6)
ngx_resolver_cleanup_tree(r, &r->addr6_rbtree);
#endif
if (r->event->timer_set) {
ngx_del_timer(r->event);
}
rec = r->connections.elts;
for (i = 0; i < r->connections.nelts; i++) {
if (rec[i].udp) {
ngx_close_connection(rec[i].udp);
}
if (rec[i].tcp) {
ngx_close_connection(rec[i].tcp);
}
if (rec[i].read_buf) {
ngx_resolver_free(r, rec[i].read_buf->start);
ngx_resolver_free(r, rec[i].read_buf);
}
if (rec[i].write_buf) {
ngx_resolver_free(r, rec[i].write_buf->start);
ngx_resolver_free(r, rec[i].write_buf);
}
}
}
static void
ngx_resolver_cleanup_tree(ngx_resolver_t *r, ngx_rbtree_t *tree)
{
ngx_resolver_ctx_t *ctx, *next;
ngx_resolver_node_t *rn;
while (tree->root != tree->sentinel) {
rn = ngx_resolver_node(ngx_rbtree_min(tree->root, tree->sentinel));
ngx_queue_remove(&rn->queue);
for (ctx = rn->waiting; ctx; ctx = next) {
next = ctx->next;
if (ctx->event) {
if (ctx->event->timer_set) {
ngx_del_timer(ctx->event);
}
ngx_resolver_free(r, ctx->event);
}
ngx_resolver_free(r, ctx);
}
ngx_rbtree_delete(tree, &rn->node);
ngx_resolver_free_node(r, rn);
}
}
ngx_resolver_ctx_t *
ngx_resolve_start(ngx_resolver_t *r, ngx_resolver_ctx_t *temp)
{
in_addr_t addr;
ngx_resolver_ctx_t *ctx;
if (temp) {
addr = ngx_inet_addr(temp->name.data, temp->name.len);
if (addr != INADDR_NONE) {
temp->resolver = r;
temp->state = NGX_OK;
temp->naddrs = 1;
temp->addrs = &temp->addr;
temp->addr.sockaddr = (struct sockaddr *) &temp->sin;
temp->addr.socklen = sizeof(struct sockaddr_in);
ngx_memzero(&temp->sin, sizeof(struct sockaddr_in));
temp->sin.sin_family = AF_INET;
temp->sin.sin_addr.s_addr = addr;
temp->quick = 1;
return temp;
}
}
if (r->connections.nelts == 0) {
return NGX_NO_RESOLVER;
}
ctx = ngx_resolver_calloc(r, sizeof(ngx_resolver_ctx_t));
if (ctx) {
ctx->resolver = r;
}
return ctx;
}
ngx_int_t
ngx_resolve_name(ngx_resolver_ctx_t *ctx)
{
size_t slen;
ngx_int_t rc;
ngx_str_t name;
ngx_resolver_t *r;
r = ctx->resolver;
if (ctx->name.len > 0 && ctx->name.data[ctx->name.len - 1] == '.') {
ctx->name.len--;
}
ngx_log_debug1(NGX_LOG_DEBUG_CORE, r->log, 0,
"resolve: \"%V\"", &ctx->name);
if (ctx->quick) {
ctx->handler(ctx);
return NGX_OK;
}
if (ctx->service.len) {
slen = ctx->service.len;
if (ngx_strlchr(ctx->service.data,
ctx->service.data + ctx->service.len, '.')
== NULL)
{
slen += sizeof("_._tcp") - 1;
}
name.len = slen + 1 + ctx->name.len;
name.data = ngx_resolver_alloc(r, name.len);
if (name.data == NULL) {
goto failed;
}
if (slen == ctx->service.len) {
ngx_sprintf(name.data, "%V.%V", &ctx->service, &ctx->name);
} else {
ngx_sprintf(name.data, "_%V._tcp.%V", &ctx->service, &ctx->name);
}
/* lock name mutex */
rc = ngx_resolve_name_locked(r, ctx, &name);
ngx_resolver_free(r, name.data);
} else {
/* lock name mutex */
rc = ngx_resolve_name_locked(r, ctx, &ctx->name);
}
if (rc == NGX_OK) {
return NGX_OK;
}
/* unlock name mutex */
if (rc == NGX_AGAIN) {
return NGX_OK;
}
/* NGX_ERROR */
if (ctx->event) {
ngx_resolver_free(r, ctx->event);
}
failed:
ngx_resolver_free(r, ctx);
return NGX_ERROR;
}
void
ngx_resolve_name_done(ngx_resolver_ctx_t *ctx)
{
ngx_uint_t i;
ngx_resolver_t *r;
ngx_resolver_ctx_t *w, **p;
ngx_resolver_node_t *rn;
r = ctx->resolver;
ngx_log_debug1(NGX_LOG_DEBUG_CORE, r->log, 0,
"resolve name done: %i", ctx->state);
if (ctx->quick) {
return;
}
if (ctx->event && ctx->event->timer_set) {
ngx_del_timer(ctx->event);
}
/* lock name mutex */
if (ctx->nsrvs) {
for (i = 0; i < ctx->nsrvs; i++) {
if (ctx->srvs[i].ctx) {
ngx_resolve_name_done(ctx->srvs[i].ctx);
}
if (ctx->srvs[i].addrs) {
ngx_resolver_free(r, ctx->srvs[i].addrs->sockaddr);
ngx_resolver_free(r, ctx->srvs[i].addrs);
}
ngx_resolver_free(r, ctx->srvs[i].name.data);
}
ngx_resolver_free(r, ctx->srvs);
}
if (ctx->state == NGX_AGAIN || ctx->state == NGX_RESOLVE_TIMEDOUT) {
rn = ctx->node;
if (rn) {
p = &rn->waiting;
w = rn->waiting;
while (w) {
if (w == ctx) {
*p = w->next;
goto done;
}
p = &w->next;
w = w->next;
}
ngx_log_error(NGX_LOG_ALERT, r->log, 0,
"could not cancel %V resolving", &ctx->name);
}
}
done:
if (ctx->service.len) {
ngx_resolver_expire(r, &r->srv_rbtree, &r->srv_expire_queue);
} else {
ngx_resolver_expire(r, &r->name_rbtree, &r->name_expire_queue);
}
/* unlock name mutex */
/* lock alloc mutex */
if (ctx->event) {
ngx_resolver_free_locked(r, ctx->event);
}
ngx_resolver_free_locked(r, ctx);
/* unlock alloc mutex */
if (r->event->timer_set && ngx_resolver_resend_empty(r)) {
ngx_del_timer(r->event);
}
}
static ngx_int_t
ngx_resolve_name_locked(ngx_resolver_t *r, ngx_resolver_ctx_t *ctx,
ngx_str_t *name)
{
uint32_t hash;
ngx_int_t rc;
ngx_str_t cname;
ngx_uint_t i, naddrs;
ngx_queue_t *resend_queue, *expire_queue;
ngx_rbtree_t *tree;
ngx_resolver_ctx_t *next, *last;
ngx_resolver_addr_t *addrs;
ngx_resolver_node_t *rn;
ngx_strlow(name->data, name->data, name->len);
hash = ngx_crc32_short(name->data, name->len);
if (ctx->service.len) {
rn = ngx_resolver_lookup_srv(r, name, hash);
tree = &r->srv_rbtree;
resend_queue = &r->srv_resend_queue;
expire_queue = &r->srv_expire_queue;
} else {
rn = ngx_resolver_lookup_name(r, name, hash);
tree = &r->name_rbtree;
resend_queue = &r->name_resend_queue;
expire_queue = &r->name_expire_queue;
}
if (rn) {
/* ctx can be a list after NGX_RESOLVE_CNAME */
for (last = ctx; last->next; last = last->next);
if (rn->valid >= ngx_time()) {
ngx_log_debug0(NGX_LOG_DEBUG_CORE, r->log, 0, "resolve cached");
ngx_queue_remove(&rn->queue);
rn->expire = ngx_time() + r->expire;
ngx_queue_insert_head(expire_queue, &rn->queue);
naddrs = (rn->naddrs == (u_short) -1) ? 0 : rn->naddrs;
#if (NGX_HAVE_INET6)
naddrs += (rn->naddrs6 == (u_short) -1) ? 0 : rn->naddrs6;
#endif
if (naddrs) {
if (naddrs == 1 && rn->naddrs == 1) {
addrs = NULL;
} else {
addrs = ngx_resolver_export(r, rn, 1);
if (addrs == NULL) {
return NGX_ERROR;
}
}
last->next = rn->waiting;
rn->waiting = NULL;
/* unlock name mutex */
do {
ctx->state = NGX_OK;
ctx->valid = rn->valid;
ctx->naddrs = naddrs;
if (addrs == NULL) {
ctx->addrs = &ctx->addr;
ctx->addr.sockaddr = (struct sockaddr *) &ctx->sin;
ctx->addr.socklen = sizeof(struct sockaddr_in);
ngx_memzero(&ctx->sin, sizeof(struct sockaddr_in));
ctx->sin.sin_family = AF_INET;
ctx->sin.sin_addr.s_addr = rn->u.addr;
} else {
ctx->addrs = addrs;
}
next = ctx->next;
ctx->handler(ctx);
ctx = next;
} while (ctx);
if (addrs != NULL) {
ngx_resolver_free(r, addrs->sockaddr);
ngx_resolver_free(r, addrs);
}
return NGX_OK;
}
if (rn->nsrvs) {
last->next = rn->waiting;
rn->waiting = NULL;
/* unlock name mutex */
do {
next = ctx->next;
ngx_resolver_resolve_srv_names(ctx, rn);
ctx = next;
} while (ctx);
return NGX_OK;
}
/* NGX_RESOLVE_CNAME */
if (ctx->recursion++ < NGX_RESOLVER_MAX_RECURSION) {
cname.len = rn->cnlen;
cname.data = rn->u.cname;
return ngx_resolve_name_locked(r, ctx, &cname);
}
last->next = rn->waiting;
rn->waiting = NULL;
/* unlock name mutex */
do {
ctx->state = NGX_RESOLVE_NXDOMAIN;
ctx->valid = ngx_time() + (r->valid ? r->valid : 10);
next = ctx->next;
ctx->handler(ctx);
ctx = next;
} while (ctx);
return NGX_OK;
}
if (rn->waiting) {
if (ngx_resolver_set_timeout(r, ctx) != NGX_OK) {
return NGX_ERROR;
}
last->next = rn->waiting;
rn->waiting = ctx;
ctx->state = NGX_AGAIN;
ctx->async = 1;
do {
ctx->node = rn;
ctx = ctx->next;
} while (ctx);
return NGX_AGAIN;
}
ngx_queue_remove(&rn->queue);
/* lock alloc mutex */
if (rn->query) {
ngx_resolver_free_locked(r, rn->query);
rn->query = NULL;
#if (NGX_HAVE_INET6)
rn->query6 = NULL;
#endif
}
if (rn->cnlen) {
ngx_resolver_free_locked(r, rn->u.cname);
}
if (rn->naddrs > 1 && rn->naddrs != (u_short) -1) {
ngx_resolver_free_locked(r, rn->u.addrs);
}
#if (NGX_HAVE_INET6)
if (rn->naddrs6 > 1 && rn->naddrs6 != (u_short) -1) {
ngx_resolver_free_locked(r, rn->u6.addrs6);
}
#endif
if (rn->nsrvs) {
for (i = 0; i < (ngx_uint_t) rn->nsrvs; i++) {
if (rn->u.srvs[i].name.data) {
ngx_resolver_free_locked(r, rn->u.srvs[i].name.data);
}
}
ngx_resolver_free_locked(r, rn->u.srvs);
}
/* unlock alloc mutex */
} else {
rn = ngx_resolver_alloc(r, sizeof(ngx_resolver_node_t));
if (rn == NULL) {
return NGX_ERROR;
}
rn->name = ngx_resolver_dup(r, name->data, name->len);
if (rn->name == NULL) {
ngx_resolver_free(r, rn);
return NGX_ERROR;
}
rn->node.key = hash;
rn->nlen = (u_short) name->len;
rn->query = NULL;
#if (NGX_HAVE_INET6)
rn->query6 = NULL;
#endif
ngx_rbtree_insert(tree, &rn->node);
}
if (ctx->service.len) {
rc = ngx_resolver_create_srv_query(r, rn, name);
} else {
rc = ngx_resolver_create_name_query(r, rn, name);
}
if (rc == NGX_ERROR) {
goto failed;
}
if (rc == NGX_DECLINED) {
ngx_rbtree_delete(tree, &rn->node);
ngx_resolver_free(r, rn->query);
ngx_resolver_free(r, rn->name);
ngx_resolver_free(r, rn);
do {
ctx->state = NGX_RESOLVE_NXDOMAIN;
next = ctx->next;
ctx->handler(ctx);
ctx = next;
} while (ctx);
return NGX_OK;
}
rn->last_connection = r->last_connection++;
if (r->last_connection == r->connections.nelts) {
r->last_connection = 0;
}
rn->naddrs = (u_short) -1;
rn->tcp = 0;
#if (NGX_HAVE_INET6)
rn->naddrs6 = r->ipv6 ? (u_short) -1 : 0;
rn->tcp6 = 0;
#endif
rn->nsrvs = 0;
if (ngx_resolver_send_query(r, rn) != NGX_OK) {
/* immediately retry once on failure */
rn->last_connection++;
if (rn->last_connection == r->connections.nelts) {
rn->last_connection = 0;
}
(void) ngx_resolver_send_query(r, rn);
}
if (ngx_resolver_set_timeout(r, ctx) != NGX_OK) {
goto failed;
}
if (ngx_resolver_resend_empty(r)) {
ngx_add_timer(r->event, (ngx_msec_t) (r->resend_timeout * 1000));
}
rn->expire = ngx_time() + r->resend_timeout;
ngx_queue_insert_head(resend_queue, &rn->queue);
rn->code = 0;
rn->cnlen = 0;
rn->valid = 0;
rn->ttl = NGX_MAX_UINT32_VALUE;
rn->waiting = ctx;
ctx->state = NGX_AGAIN;
ctx->async = 1;
do {
ctx->node = rn;
ctx = ctx->next;
} while (ctx);
return NGX_AGAIN;
failed:
ngx_rbtree_delete(tree, &rn->node);
if (rn->query) {
ngx_resolver_free(r, rn->query);
}
ngx_resolver_free(r, rn->name);
ngx_resolver_free(r, rn);
return NGX_ERROR;
}
ngx_int_t
ngx_resolve_addr(ngx_resolver_ctx_t *ctx)
{
u_char *name;
in_addr_t addr;
ngx_queue_t *resend_queue, *expire_queue;
ngx_rbtree_t *tree;
ngx_resolver_t *r;
struct sockaddr_in *sin;
ngx_resolver_node_t *rn;
#if (NGX_HAVE_INET6)
uint32_t hash;
struct sockaddr_in6 *sin6;
#endif
#if (NGX_SUPPRESS_WARN)
addr = 0;
#if (NGX_HAVE_INET6)
hash = 0;
sin6 = NULL;
#endif
#endif
r = ctx->resolver;
switch (ctx->addr.sockaddr->sa_family) {
#if (NGX_HAVE_INET6)
case AF_INET6:
sin6 = (struct sockaddr_in6 *) ctx->addr.sockaddr;
hash = ngx_crc32_short(sin6->sin6_addr.s6_addr, 16);
/* lock addr mutex */
rn = ngx_resolver_lookup_addr6(r, &sin6->sin6_addr, hash);
tree = &r->addr6_rbtree;
resend_queue = &r->addr6_resend_queue;
expire_queue = &r->addr6_expire_queue;
break;
#endif
default: /* AF_INET */
sin = (struct sockaddr_in *) ctx->addr.sockaddr;
addr = ntohl(sin->sin_addr.s_addr);
/* lock addr mutex */
rn = ngx_resolver_lookup_addr(r, addr);
tree = &r->addr_rbtree;
resend_queue = &r->addr_resend_queue;
expire_queue = &r->addr_expire_queue;
}
if (rn) {
if (rn->valid >= ngx_time()) {
ngx_log_debug0(NGX_LOG_DEBUG_CORE, r->log, 0, "resolve cached");
ngx_queue_remove(&rn->queue);
rn->expire = ngx_time() + r->expire;
ngx_queue_insert_head(expire_queue, &rn->queue);
name = ngx_resolver_dup(r, rn->name, rn->nlen);
if (name == NULL) {
ngx_resolver_free(r, ctx);
return NGX_ERROR;
}
ctx->name.len = rn->nlen;
ctx->name.data = name;
/* unlock addr mutex */
ctx->state = NGX_OK;
ctx->valid = rn->valid;
ctx->handler(ctx);
ngx_resolver_free(r, name);
return NGX_OK;
}
if (rn->waiting) {
if (ngx_resolver_set_timeout(r, ctx) != NGX_OK) {
return NGX_ERROR;
}
ctx->next = rn->waiting;
rn->waiting = ctx;
ctx->state = NGX_AGAIN;
ctx->async = 1;
ctx->node = rn;
/* unlock addr mutex */
return NGX_OK;
}
ngx_queue_remove(&rn->queue);
ngx_resolver_free(r, rn->query);
rn->query = NULL;
#if (NGX_HAVE_INET6)
rn->query6 = NULL;
#endif
} else {
rn = ngx_resolver_alloc(r, sizeof(ngx_resolver_node_t));
if (rn == NULL) {
goto failed;
}
switch (ctx->addr.sockaddr->sa_family) {
#if (NGX_HAVE_INET6)
case AF_INET6:
rn->addr6 = sin6->sin6_addr;
rn->node.key = hash;
break;
#endif
default: /* AF_INET */
rn->node.key = addr;
}
rn->query = NULL;
#if (NGX_HAVE_INET6)
rn->query6 = NULL;
#endif
ngx_rbtree_insert(tree, &rn->node);
}
if (ngx_resolver_create_addr_query(r, rn, &ctx->addr) != NGX_OK) {
goto failed;
}
rn->last_connection = r->last_connection++;
if (r->last_connection == r->connections.nelts) {
r->last_connection = 0;
}
rn->naddrs = (u_short) -1;
rn->tcp = 0;
#if (NGX_HAVE_INET6)
rn->naddrs6 = (u_short) -1;
rn->tcp6 = 0;
#endif
rn->nsrvs = 0;
if (ngx_resolver_send_query(r, rn) != NGX_OK) {
/* immediately retry once on failure */
rn->last_connection++;
if (rn->last_connection == r->connections.nelts) {
rn->last_connection = 0;
}
(void) ngx_resolver_send_query(r, rn);
}
if (ngx_resolver_set_timeout(r, ctx) != NGX_OK) {
goto failed;
}
if (ngx_resolver_resend_empty(r)) {
ngx_add_timer(r->event, (ngx_msec_t) (r->resend_timeout * 1000));
}
rn->expire = ngx_time() + r->resend_timeout;
ngx_queue_insert_head(resend_queue, &rn->queue);
rn->code = 0;
rn->cnlen = 0;
rn->name = NULL;
rn->nlen = 0;
rn->valid = 0;
rn->ttl = NGX_MAX_UINT32_VALUE;
rn->waiting = ctx;
/* unlock addr mutex */
ctx->state = NGX_AGAIN;
ctx->async = 1;
ctx->node = rn;
return NGX_OK;
failed:
if (rn) {
ngx_rbtree_delete(tree, &rn->node);
if (rn->query) {
ngx_resolver_free(r, rn->query);
}
ngx_resolver_free(r, rn);
}
/* unlock addr mutex */
if (ctx->event) {
ngx_resolver_free(r, ctx->event);
}
ngx_resolver_free(r, ctx);
return NGX_ERROR;
}
void
ngx_resolve_addr_done(ngx_resolver_ctx_t *ctx)
{
ngx_queue_t *expire_queue;
ngx_rbtree_t *tree;
ngx_resolver_t *r;
ngx_resolver_ctx_t *w, **p;
ngx_resolver_node_t *rn;
r = ctx->resolver;
switch (ctx->addr.sockaddr->sa_family) {
#if (NGX_HAVE_INET6)
case AF_INET6:
tree = &r->addr6_rbtree;
expire_queue = &r->addr6_expire_queue;
break;
#endif
default: /* AF_INET */
tree = &r->addr_rbtree;
expire_queue = &r->addr_expire_queue;
}
ngx_log_debug1(NGX_LOG_DEBUG_CORE, r->log, 0,
"resolve addr done: %i", ctx->state);
if (ctx->event && ctx->event->timer_set) {
ngx_del_timer(ctx->event);
}
/* lock addr mutex */
if (ctx->state == NGX_AGAIN || ctx->state == NGX_RESOLVE_TIMEDOUT) {
rn = ctx->node;
if (rn) {
p = &rn->waiting;
w = rn->waiting;
while (w) {
if (w == ctx) {
*p = w->next;
goto done;
}
p = &w->next;
w = w->next;
}
}
{
u_char text[NGX_SOCKADDR_STRLEN];
ngx_str_t addrtext;
addrtext.data = text;
addrtext.len = ngx_sock_ntop(ctx->addr.sockaddr, ctx->addr.socklen,
text, NGX_SOCKADDR_STRLEN, 0);
ngx_log_error(NGX_LOG_ALERT, r->log, 0,
"could not cancel %V resolving", &addrtext);
}
}
done:
ngx_resolver_expire(r, tree, expire_queue);
/* unlock addr mutex */
/* lock alloc mutex */
if (ctx->event) {
ngx_resolver_free_locked(r, ctx->event);
}
ngx_resolver_free_locked(r, ctx);
/* unlock alloc mutex */
if (r->event->timer_set && ngx_resolver_resend_empty(r)) {
ngx_del_timer(r->event);
}
}
static void
ngx_resolver_expire(ngx_resolver_t *r, ngx_rbtree_t *tree, ngx_queue_t *queue)
{
time_t now;
ngx_uint_t i;
ngx_queue_t *q;
ngx_resolver_node_t *rn;
ngx_log_debug0(NGX_LOG_DEBUG_CORE, r->log, 0, "resolver expire");
now = ngx_time();
for (i = 0; i < 2; i++) {
if (ngx_queue_empty(queue)) {
return;
}
q = ngx_queue_last(queue);
rn = ngx_queue_data(q, ngx_resolver_node_t, queue);
if (now <= rn->expire) {
return;
}
ngx_log_debug2(NGX_LOG_DEBUG_CORE, r->log, 0,
"resolver expire \"%*s\"", (size_t) rn->nlen, rn->name);
ngx_queue_remove(q);
ngx_rbtree_delete(tree, &rn->node);
ngx_resolver_free_node(r, rn);
}
}
static ngx_int_t
ngx_resolver_send_query(ngx_resolver_t *r, ngx_resolver_node_t *rn)
{
ngx_int_t rc;
ngx_resolver_connection_t *rec;
rec = r->connections.elts;
rec = &rec[rn->last_connection];
if (rec->log.handler == NULL) {
rec->log = *r->log;
rec->log.handler = ngx_resolver_log_error;
rec->log.data = rec;
rec->log.action = "resolving";
}
if (rn->naddrs == (u_short) -1) {
rc = rn->tcp ? ngx_resolver_send_tcp_query(r, rec, rn->query, rn->qlen)
: ngx_resolver_send_udp_query(r, rec, rn->query, rn->qlen);
if (rc != NGX_OK) {
return rc;
}
}
#if (NGX_HAVE_INET6)
if (rn->query6 && rn->naddrs6 == (u_short) -1) {
rc = rn->tcp6
? ngx_resolver_send_tcp_query(r, rec, rn->query6, rn->qlen)
: ngx_resolver_send_udp_query(r, rec, rn->query6, rn->qlen);
if (rc != NGX_OK) {
return rc;
}
}
#endif
return NGX_OK;
}
static ngx_int_t
ngx_resolver_send_udp_query(ngx_resolver_t *r, ngx_resolver_connection_t *rec,
u_char *query, u_short qlen)
{
ssize_t n;
if (rec->udp == NULL) {
if (ngx_udp_connect(rec) != NGX_OK) {
return NGX_ERROR;
}
rec->udp->data = rec;
rec->udp->read->handler = ngx_resolver_udp_read;
rec->udp->read->resolver = 1;
}
n = ngx_send(rec->udp, query, qlen);
if (n == NGX_ERROR) {
goto failed;
}
if ((size_t) n != (size_t) qlen) {
ngx_log_error(NGX_LOG_CRIT, &rec->log, 0, "send() incomplete");
goto failed;
}
return NGX_OK;
failed:
ngx_close_connection(rec->udp);
rec->udp = NULL;
return NGX_ERROR;
}
static ngx_int_t
ngx_resolver_send_tcp_query(ngx_resolver_t *r, ngx_resolver_connection_t *rec,
u_char *query, u_short qlen)
{
ngx_buf_t *b;
ngx_int_t rc;
rc = NGX_OK;
if (rec->tcp == NULL) {
b = rec->read_buf;
if (b == NULL) {
b = ngx_resolver_calloc(r, sizeof(ngx_buf_t));
if (b == NULL) {
return NGX_ERROR;
}
b->start = ngx_resolver_alloc(r, NGX_RESOLVER_TCP_RSIZE);
if (b->start == NULL) {
ngx_resolver_free(r, b);
return NGX_ERROR;
}
b->end = b->start + NGX_RESOLVER_TCP_RSIZE;
rec->read_buf = b;
}
b->pos = b->start;
b->last = b->start;
b = rec->write_buf;
if (b == NULL) {
b = ngx_resolver_calloc(r, sizeof(ngx_buf_t));
if (b == NULL) {
return NGX_ERROR;
}
b->start = ngx_resolver_alloc(r, NGX_RESOLVER_TCP_WSIZE);
if (b->start == NULL) {
ngx_resolver_free(r, b);
return NGX_ERROR;
}
b->end = b->start + NGX_RESOLVER_TCP_WSIZE;
rec->write_buf = b;
}
b->pos = b->start;
b->last = b->start;
rc = ngx_tcp_connect(rec);
if (rc == NGX_ERROR) {
return NGX_ERROR;
}
rec->tcp->data = rec;
rec->tcp->write->handler = ngx_resolver_tcp_write;
rec->tcp->read->handler = ngx_resolver_tcp_read;
rec->tcp->read->resolver = 1;
ngx_add_timer(rec->tcp->write, (ngx_msec_t) (r->tcp_timeout * 1000));
}
b = rec->write_buf;
if (b->end - b->last < 2 + qlen) {
ngx_log_error(NGX_LOG_CRIT, &rec->log, 0, "buffer overflow");
return NGX_ERROR;
}
*b->last++ = (u_char) (qlen >> 8);
*b->last++ = (u_char) qlen;
b->last = ngx_cpymem(b->last, query, qlen);
if (rc == NGX_OK) {
ngx_resolver_tcp_write(rec->tcp->write);
}
return NGX_OK;
}
static void
ngx_resolver_resend_handler(ngx_event_t *ev)
{
time_t timer, atimer, stimer, ntimer;
#if (NGX_HAVE_INET6)
time_t a6timer;
#endif
ngx_resolver_t *r;
r = ev->data;
ngx_log_debug0(NGX_LOG_DEBUG_CORE, r->log, 0,
"resolver resend handler");
/* lock name mutex */
ntimer = ngx_resolver_resend(r, &r->name_rbtree, &r->name_resend_queue);
stimer = ngx_resolver_resend(r, &r->srv_rbtree, &r->srv_resend_queue);
/* unlock name mutex */
/* lock addr mutex */
atimer = ngx_resolver_resend(r, &r->addr_rbtree, &r->addr_resend_queue);
/* unlock addr mutex */
#if (NGX_HAVE_INET6)
/* lock addr6 mutex */
a6timer = ngx_resolver_resend(r, &r->addr6_rbtree, &r->addr6_resend_queue);
/* unlock addr6 mutex */
#endif
timer = ntimer;
if (timer == 0) {
timer = atimer;
} else if (atimer) {
timer = ngx_min(timer, atimer);
}
if (timer == 0) {
timer = stimer;
} else if (stimer) {
timer = ngx_min(timer, stimer);
}
#if (NGX_HAVE_INET6)
if (timer == 0) {
timer = a6timer;
} else if (a6timer) {
timer = ngx_min(timer, a6timer);
}
#endif
if (timer) {
ngx_add_timer(r->event, (ngx_msec_t) (timer * 1000));
}
}
static time_t
ngx_resolver_resend(ngx_resolver_t *r, ngx_rbtree_t *tree, ngx_queue_t *queue)
{
time_t now;
ngx_queue_t *q;
ngx_resolver_node_t *rn;
now = ngx_time();
for ( ;; ) {
if (ngx_queue_empty(queue)) {
return 0;
}
q = ngx_queue_last(queue);
rn = ngx_queue_data(q, ngx_resolver_node_t, queue);
if (now < rn->expire) {
return rn->expire - now;
}
ngx_log_debug3(NGX_LOG_DEBUG_CORE, r->log, 0,
"resolver resend \"%*s\" %p",
(size_t) rn->nlen, rn->name, rn->waiting);
ngx_queue_remove(q);
if (rn->waiting) {
if (++rn->last_connection == r->connections.nelts) {
rn->last_connection = 0;
}
(void) ngx_resolver_send_query(r, rn);
rn->expire = now + r->resend_timeout;
ngx_queue_insert_head(queue, q);
continue;
}
ngx_rbtree_delete(tree, &rn->node);
ngx_resolver_free_node(r, rn);
}
}
static ngx_uint_t
ngx_resolver_resend_empty(ngx_resolver_t *r)
{
return ngx_queue_empty(&r->name_resend_queue)
&& ngx_queue_empty(&r->srv_resend_queue)
#if (NGX_HAVE_INET6)
&& ngx_queue_empty(&r->addr6_resend_queue)
#endif
&& ngx_queue_empty(&r->addr_resend_queue);
}
static void
ngx_resolver_udp_read(ngx_event_t *rev)
{
ssize_t n;
ngx_connection_t *c;
ngx_resolver_connection_t *rec;
u_char buf[NGX_RESOLVER_UDP_SIZE];
c = rev->data;
rec = c->data;
do {
n = ngx_udp_recv(c, buf, NGX_RESOLVER_UDP_SIZE);
if (n == NGX_AGAIN) {
break;
}
if (n == NGX_ERROR) {
goto failed;
}
ngx_resolver_process_response(rec->resolver, buf, n, 0);
} while (rev->ready);
if (ngx_handle_read_event(rev, 0) != NGX_OK) {
goto failed;
}
return;
failed:
ngx_close_connection(rec->udp);
rec->udp = NULL;
}
static void
ngx_resolver_tcp_write(ngx_event_t *wev)
{
off_t sent;
ssize_t n;
ngx_buf_t *b;
ngx_resolver_t *r;
ngx_connection_t *c;
ngx_resolver_connection_t *rec;
c = wev->data;
rec = c->data;
b = rec->write_buf;
r = rec->resolver;
if (wev->timedout) {
goto failed;
}
sent = c->sent;
while (wev->ready && b->pos < b->last) {
n = ngx_send(c, b->pos, b->last - b->pos);
if (n == NGX_AGAIN) {
break;
}
if (n == NGX_ERROR) {
goto failed;
}
b->pos += n;
}
if (b->pos != b->start) {
b->last = ngx_movemem(b->start, b->pos, b->last - b->pos);
b->pos = b->start;
}
if (c->sent != sent) {
ngx_add_timer(wev, (ngx_msec_t) (r->tcp_timeout * 1000));
}
if (ngx_handle_write_event(wev, 0) != NGX_OK) {
goto failed;
}
return;
failed:
ngx_close_connection(c);
rec->tcp = NULL;
}
static void
ngx_resolver_tcp_read(ngx_event_t *rev)
{
u_char *p;
size_t size;
ssize_t n;
u_short qlen;
ngx_buf_t *b;
ngx_resolver_t *r;
ngx_connection_t *c;
ngx_resolver_connection_t *rec;
c = rev->data;
rec = c->data;
b = rec->read_buf;
r = rec->resolver;
while (rev->ready) {
n = ngx_recv(c, b->last, b->end - b->last);
if (n == NGX_AGAIN) {
break;
}
if (n == NGX_ERROR || n == 0) {
goto failed;
}
b->last += n;
for ( ;; ) {
p = b->pos;
size = b->last - p;
if (size < 2) {
break;
}
qlen = (u_short) *p++ << 8;
qlen += *p++;
if (size < (size_t) (2 + qlen)) {
break;
}
ngx_resolver_process_response(r, p, qlen, 1);
b->pos += 2 + qlen;
}
if (b->pos != b->start) {
b->last = ngx_movemem(b->start, b->pos, b->last - b->pos);
b->pos = b->start;
}
}
if (ngx_handle_read_event(rev, 0) != NGX_OK) {
goto failed;
}
return;
failed:
ngx_close_connection(c);
rec->tcp = NULL;
}
static void
ngx_resolver_process_response(ngx_resolver_t *r, u_char *buf, size_t n,
ngx_uint_t tcp)
{
char *err;
ngx_uint_t i, times, ident, qident, flags, code, nqs, nan, trunc,
qtype, qclass;
#if (NGX_HAVE_INET6)
ngx_uint_t qident6;
#endif
ngx_queue_t *q;
ngx_resolver_qs_t *qs;
ngx_resolver_hdr_t *response;
ngx_resolver_node_t *rn;
if (n < sizeof(ngx_resolver_hdr_t)) {
goto short_response;
}
response = (ngx_resolver_hdr_t *) buf;
ident = (response->ident_hi << 8) + response->ident_lo;
flags = (response->flags_hi << 8) + response->flags_lo;
nqs = (response->nqs_hi << 8) + response->nqs_lo;
nan = (response->nan_hi << 8) + response->nan_lo;
trunc = flags & 0x0200;
ngx_log_debug6(NGX_LOG_DEBUG_CORE, r->log, 0,
"resolver DNS response %ui fl:%04Xi %ui/%ui/%ud/%ud",
ident, flags, nqs, nan,
(response->nns_hi << 8) + response->nns_lo,
(response->nar_hi << 8) + response->nar_lo);
/* response to a standard query */
if ((flags & 0xf870) != 0x8000 || (trunc && tcp)) {
ngx_log_error(r->log_level, r->log, 0,
"invalid %s DNS response %ui fl:%04Xi",
tcp ? "TCP" : "UDP", ident, flags);
return;
}
code = flags & 0xf;
if (code == NGX_RESOLVE_FORMERR) {
times = 0;
for (q = ngx_queue_head(&r->name_resend_queue);
q != ngx_queue_sentinel(&r->name_resend_queue) && times++ < 100;
q = ngx_queue_next(q))
{
rn = ngx_queue_data(q, ngx_resolver_node_t, queue);
qident = (rn->query[0] << 8) + rn->query[1];
if (qident == ident) {
goto dns_error_name;
}
#if (NGX_HAVE_INET6)
if (rn->query6) {
qident6 = (rn->query6[0] << 8) + rn->query6[1];
if (qident6 == ident) {
goto dns_error_name;
}
}
#endif
}
goto dns_error;
}
if (code > NGX_RESOLVE_REFUSED) {
goto dns_error;
}
if (nqs != 1) {
err = "invalid number of questions in DNS response";
goto done;
}
i = sizeof(ngx_resolver_hdr_t);
while (i < (ngx_uint_t) n) {
if (buf[i] & 0xc0) {
err = "unexpected compression pointer in DNS response";
goto done;
}
if (buf[i] == '\0') {
goto found;
}
i += 1 + buf[i];
}
goto short_response;
found:
if (i++ == sizeof(ngx_resolver_hdr_t)) {
err = "zero-length domain name in DNS response";
goto done;
}
if (i + sizeof(ngx_resolver_qs_t) + nan * (2 + sizeof(ngx_resolver_an_t))
> (ngx_uint_t) n)
{
goto short_response;
}
qs = (ngx_resolver_qs_t *) &buf[i];
qtype = (qs->type_hi << 8) + qs->type_lo;
qclass = (qs->class_hi << 8) + qs->class_lo;
ngx_log_debug2(NGX_LOG_DEBUG_CORE, r->log, 0,
"resolver DNS response qt:%ui cl:%ui", qtype, qclass);
if (qclass != 1) {
ngx_log_error(r->log_level, r->log, 0,
"unknown query class %ui in DNS response", qclass);
return;
}
switch (qtype) {
case NGX_RESOLVE_A:
#if (NGX_HAVE_INET6)
case NGX_RESOLVE_AAAA:
#endif
ngx_resolver_process_a(r, buf, n, ident, code, qtype, nan, trunc,
i + sizeof(ngx_resolver_qs_t));
break;
case NGX_RESOLVE_SRV:
ngx_resolver_process_srv(r, buf, n, ident, code, nan, trunc,
i + sizeof(ngx_resolver_qs_t));
break;
case NGX_RESOLVE_PTR:
ngx_resolver_process_ptr(r, buf, n, ident, code, nan);
break;
default:
ngx_log_error(r->log_level, r->log, 0,
"unknown query type %ui in DNS response", qtype);
return;
}
return;
short_response:
err = "short DNS response";
done:
ngx_log_error(r->log_level, r->log, 0, err);
return;
dns_error_name:
ngx_log_error(r->log_level, r->log, 0,
"DNS error (%ui: %s), query id:%ui, name:\"%*s\"",
code, ngx_resolver_strerror(code), ident,
(size_t) rn->nlen, rn->name);
return;
dns_error:
ngx_log_error(r->log_level, r->log, 0,
"DNS error (%ui: %s), query id:%ui",
code, ngx_resolver_strerror(code), ident);
return;
}
static void
ngx_resolver_process_a(ngx_resolver_t *r, u_char *buf, size_t n,
ngx_uint_t ident, ngx_uint_t code, ngx_uint_t qtype,
ngx_uint_t nan, ngx_uint_t trunc, ngx_uint_t ans)
{
char *err;
u_char *cname;
size_t len;
int32_t ttl;
uint32_t hash;
in_addr_t *addr;
ngx_str_t name;
ngx_uint_t type, class, qident, naddrs, a, i, j, start;
#if (NGX_HAVE_INET6)
struct in6_addr *addr6;
#endif
ngx_resolver_an_t *an;
ngx_resolver_ctx_t *ctx, *next;
ngx_resolver_node_t *rn;
ngx_resolver_addr_t *addrs;
ngx_resolver_connection_t *rec;
if (ngx_resolver_copy(r, &name, buf,
buf + sizeof(ngx_resolver_hdr_t), buf + n)
!= NGX_OK)
{
return;
}
ngx_log_debug1(NGX_LOG_DEBUG_CORE, r->log, 0, "resolver qs:%V", &name);
hash = ngx_crc32_short(name.data, name.len);
/* lock name mutex */
rn = ngx_resolver_lookup_name(r, &name, hash);
if (rn == NULL) {
ngx_log_error(r->log_level, r->log, 0,
"unexpected DNS response for %V", &name);
ngx_resolver_free(r, name.data);
goto failed;
}
switch (qtype) {
#if (NGX_HAVE_INET6)
case NGX_RESOLVE_AAAA:
if (rn->query6 == NULL || rn->naddrs6 != (u_short) -1) {
ngx_log_error(r->log_level, r->log, 0,
"unexpected DNS response for %V", &name);
ngx_resolver_free(r, name.data);
goto failed;
}
if (trunc && rn->tcp6) {
ngx_resolver_free(r, name.data);
goto failed;
}
qident = (rn->query6[0] << 8) + rn->query6[1];
break;
#endif
default: /* NGX_RESOLVE_A */
if (rn->query == NULL || rn->naddrs != (u_short) -1) {
ngx_log_error(r->log_level, r->log, 0,
"unexpected DNS response for %V", &name);
ngx_resolver_free(r, name.data);
goto failed;
}
if (trunc && rn->tcp) {
ngx_resolver_free(r, name.data);
goto failed;
}
qident = (rn->query[0] << 8) + rn->query[1];
}
if (ident != qident) {
ngx_log_error(r->log_level, r->log, 0,
"wrong ident %ui in DNS response for %V, expect %ui",
ident, &name, qident);
ngx_resolver_free(r, name.data);
goto failed;
}
ngx_resolver_free(r, name.data);
if (trunc) {
ngx_queue_remove(&rn->queue);
if (rn->waiting == NULL) {
ngx_rbtree_delete(&r->name_rbtree, &rn->node);
ngx_resolver_free_node(r, rn);
goto next;
}
rec = r->connections.elts;
rec = &rec[rn->last_connection];
switch (qtype) {
#if (NGX_HAVE_INET6)
case NGX_RESOLVE_AAAA:
rn->tcp6 = 1;
(void) ngx_resolver_send_tcp_query(r, rec, rn->query6, rn->qlen);
break;
#endif
default: /* NGX_RESOLVE_A */
rn->tcp = 1;
(void) ngx_resolver_send_tcp_query(r, rec, rn->query, rn->qlen);
}
rn->expire = ngx_time() + r->resend_timeout;
ngx_queue_insert_head(&r->name_resend_queue, &rn->queue);
goto next;
}
if (code == 0 && rn->code) {
code = rn->code;
}
if (code == 0 && nan == 0) {
#if (NGX_HAVE_INET6)
switch (qtype) {
case NGX_RESOLVE_AAAA:
rn->naddrs6 = 0;
if (rn->naddrs == (u_short) -1) {
goto next;
}
if (rn->naddrs) {
goto export;
}
break;
default: /* NGX_RESOLVE_A */
rn->naddrs = 0;
if (rn->naddrs6 == (u_short) -1) {
goto next;
}
if (rn->naddrs6) {
goto export;
}
}
#endif
code = NGX_RESOLVE_NXDOMAIN;
}
if (code) {
#if (NGX_HAVE_INET6)
switch (qtype) {
case NGX_RESOLVE_AAAA:
rn->naddrs6 = 0;
if (rn->naddrs == (u_short) -1) {
rn->code = (u_char) code;
goto next;
}
break;
default: /* NGX_RESOLVE_A */
rn->naddrs = 0;
if (rn->naddrs6 == (u_short) -1) {
rn->code = (u_char) code;
goto next;
}
}
#endif
next = rn->waiting;
rn->waiting = NULL;
ngx_queue_remove(&rn->queue);
ngx_rbtree_delete(&r->name_rbtree, &rn->node);
/* unlock name mutex */
while (next) {
ctx = next;
ctx->state = code;
ctx->valid = ngx_time() + (r->valid ? r->valid : 10);
next = ctx->next;
ctx->handler(ctx);
}
ngx_resolver_free_node(r, rn);
return;
}
i = ans;
naddrs = 0;
cname = NULL;
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 in DNS response", class);
goto failed;
}
if (ttl < 0) {
ttl = 0;
}
rn->ttl = ngx_min(rn->ttl, (uint32_t) ttl);
i += sizeof(ngx_resolver_an_t);
switch (type) {
case NGX_RESOLVE_A:
if (qtype != NGX_RESOLVE_A) {
err = "unexpected A record in DNS response";
goto invalid;
}
if (len != 4) {
err = "invalid A record in DNS response";
goto invalid;
}
if (i + 4 > n) {
goto short_response;
}
naddrs++;
break;
#if (NGX_HAVE_INET6)
case NGX_RESOLVE_AAAA:
if (qtype != NGX_RESOLVE_AAAA) {
err = "unexpected AAAA record in DNS response";
goto invalid;
}
if (len != 16) {
err = "invalid AAAA record in DNS response";
goto invalid;
}
if (i + 16 > n) {
goto short_response;
}
naddrs++;
break;
#endif
case NGX_RESOLVE_CNAME:
cname = &buf[i];
break;
case NGX_RESOLVE_DNAME:
break;
default:
ngx_log_error(r->log_level, r->log, 0,
"unexpected RR type %ui in DNS response", type);
}
i += len;
}
ngx_log_debug3(NGX_LOG_DEBUG_CORE, r->log, 0,
"resolver naddrs:%ui cname:%p ttl:%uD",
naddrs, cname, rn->ttl);
if (naddrs) {
switch (qtype) {
#if (NGX_HAVE_INET6)
case NGX_RESOLVE_AAAA:
if (naddrs == 1) {
addr6 = &rn->u6.addr6;
rn->naddrs6 = 1;
} else {
addr6 = ngx_resolver_alloc(r, naddrs * sizeof(struct in6_addr));
if (addr6 == NULL) {
goto failed;
}
rn->u6.addrs6 = addr6;
rn->naddrs6 = (u_short) naddrs;
}
#if (NGX_SUPPRESS_WARN)
addr = NULL;
#endif
break;
#endif
default: /* NGX_RESOLVE_A */
if (naddrs == 1) {
addr = &rn->u.addr;
rn->naddrs = 1;
} else {
addr = ngx_resolver_alloc(r, naddrs * sizeof(in_addr_t));
if (addr == NULL) {
goto failed;
}
rn->u.addrs = addr;
rn->naddrs = (u_short) naddrs;
}
#if (NGX_HAVE_INET6 && NGX_SUPPRESS_WARN)
addr6 = NULL;
#endif
}
j = 0;
i = ans;
for (a = 0; a < nan; a++) {
for ( ;; ) {
if (buf[i] & 0xc0) {
i += 2;
break;
}
if (buf[i] == 0) {
i++;
break;
}
i += 1 + buf[i];
}
an = (ngx_resolver_an_t *) &buf[i];
type = (an->type_hi << 8) + an->type_lo;
len = (an->len_hi << 8) + an->len_lo;
i += sizeof(ngx_resolver_an_t);
if (type == NGX_RESOLVE_A) {
addr[j] = htonl((buf[i] << 24) + (buf[i + 1] << 16)
+ (buf[i + 2] << 8) + (buf[i + 3]));
if (++j == naddrs) {
#if (NGX_HAVE_INET6)
if (rn->naddrs6 == (u_short) -1) {
goto next;
}
#endif
break;
}
}
#if (NGX_HAVE_INET6)
else if (type == NGX_RESOLVE_AAAA) {
ngx_memcpy(addr6[j].s6_addr, &buf[i], 16);
if (++j == naddrs) {
if (rn->naddrs == (u_short) -1) {
goto next;
}
break;
}
}
#endif
i += len;
}
}
switch (qtype) {
#if (NGX_HAVE_INET6)
case NGX_RESOLVE_AAAA:
if (rn->naddrs6 == (u_short) -1) {
rn->naddrs6 = 0;
}
break;
#endif
default: /* NGX_RESOLVE_A */
if (rn->naddrs == (u_short) -1) {
rn->naddrs = 0;
}
}
if (rn->naddrs != (u_short) -1
#if (NGX_HAVE_INET6)
&& rn->naddrs6 != (u_short) -1
#endif
&& rn->naddrs
#if (NGX_HAVE_INET6)
+ rn->naddrs6
#endif
> 0)
{
#if (NGX_HAVE_INET6)
export:
#endif
naddrs = rn->naddrs;
#if (NGX_HAVE_INET6)
naddrs += rn->naddrs6;
#endif
if (naddrs == 1 && rn->naddrs == 1) {
addrs = NULL;
} else {
addrs = ngx_resolver_export(r, rn, 0);
if (addrs == NULL) {
goto failed;
}
}
ngx_queue_remove(&rn->queue);
rn->valid = ngx_time() + (r->valid ? r->valid : (time_t) rn->ttl);
rn->expire = ngx_time() + r->expire;
ngx_queue_insert_head(&r->name_expire_queue, &rn->queue);
next = rn->waiting;
rn->waiting = NULL;
/* unlock name mutex */
while (next) {
ctx = next;
ctx->state = NGX_OK;
ctx->valid = rn->valid;
ctx->naddrs = naddrs;
if (addrs == NULL) {
ctx->addrs = &ctx->addr;
ctx->addr.sockaddr = (struct sockaddr *) &ctx->sin;
ctx->addr.socklen = sizeof(struct sockaddr_in);
ngx_memzero(&ctx->sin, sizeof(struct sockaddr_in));
ctx->sin.sin_family = AF_INET;
ctx->sin.sin_addr.s_addr = rn->u.addr;
} else {
ctx->addrs = addrs;
}
next = ctx->next;
ctx->handler(ctx);
}
if (addrs != NULL) {
ngx_resolver_free(r, addrs->sockaddr);
ngx_resolver_free(r, addrs);
}
ngx_resolver_free(r, rn->query);
rn->query = NULL;
#if (NGX_HAVE_INET6)
rn->query6 = NULL;
#endif
return;
}
if (cname) {
/* CNAME only */
if (rn->naddrs == (u_short) -1
#if (NGX_HAVE_INET6)
|| rn->naddrs6 == (u_short) -1
#endif
)
{
goto next;
}
if (ngx_resolver_copy(r, &name, buf, cname, buf + n) != NGX_OK) {
goto failed;
}
ngx_log_debug1(NGX_LOG_DEBUG_CORE, r->log, 0,
"resolver cname:\"%V\"", &name);
ngx_queue_remove(&rn->queue);
rn->cnlen = (u_short) name.len;
rn->u.cname = name.data;
rn->valid = ngx_time() + (r->valid ? r->valid : (time_t) rn->ttl);
rn->expire = ngx_time() + r->expire;
ngx_queue_insert_head(&r->name_expire_queue, &rn->queue);
ngx_resolver_free(r, rn->query);
rn->query = NULL;
#if (NGX_HAVE_INET6)
rn->query6 = NULL;
#endif
ctx = rn->waiting;
rn->waiting = NULL;
if (ctx) {
if (ctx->recursion++ >= NGX_RESOLVER_MAX_RECURSION) {
/* unlock name mutex */
do {
ctx->state = NGX_RESOLVE_NXDOMAIN;
next = ctx->next;
ctx->handler(ctx);
ctx = next;
} while (ctx);
return;
}
for (next = ctx; next; next = next->next) {
next->node = NULL;
}
(void) ngx_resolve_name_locked(r, ctx, &name);
}
/* unlock name mutex */
return;
}
ngx_log_error(r->log_level, r->log, 0,
"no A or CNAME types in DNS response");
return;
short_response:
err = "short DNS response";
invalid:
/* unlock name mutex */
ngx_log_error(r->log_level, r->log, 0, err);
return;
failed:
next:
/* unlock name mutex */
return;
}
static void
ngx_resolver_process_srv(ngx_resolver_t *r, u_char *buf, size_t n,
ngx_uint_t ident, ngx_uint_t code, ngx_uint_t nan,
ngx_uint_t trunc, ngx_uint_t ans)
{
char *err;
u_char *cname;
size_t len;
int32_t ttl;
uint32_t hash;
ngx_str_t name;
ngx_uint_t type, qident, class, start, nsrvs, a, i, j;
ngx_resolver_an_t *an;
ngx_resolver_ctx_t *ctx, *next;
ngx_resolver_srv_t *srvs;
ngx_resolver_node_t *rn;
ngx_resolver_connection_t *rec;
if (ngx_resolver_copy(r, &name, buf,
buf + sizeof(ngx_resolver_hdr_t), buf + n)
!= NGX_OK)
{
return;
}
ngx_log_debug1(NGX_LOG_DEBUG_CORE, r->log, 0, "resolver qs:%V", &name);
hash = ngx_crc32_short(name.data, name.len);
rn = ngx_resolver_lookup_srv(r, &name, hash);
if (rn == NULL || rn->query == NULL) {
ngx_log_error(r->log_level, r->log, 0,
"unexpected DNS response for %V", &name);
ngx_resolver_free(r, name.data);
goto failed;
}
if (trunc && rn->tcp) {
ngx_resolver_free(r, name.data);
goto failed;
}
qident = (rn->query[0] << 8) + rn->query[1];
if (ident != qident) {
ngx_log_error(r->log_level, r->log, 0,
"wrong ident %ui in DNS response for %V, expect %ui",
ident, &name, qident);
ngx_resolver_free(r, name.data);
goto failed;
}
ngx_resolver_free(r, name.data);
if (trunc) {
ngx_queue_remove(&rn->queue);
if (rn->waiting == NULL) {
ngx_rbtree_delete(&r->srv_rbtree, &rn->node);
ngx_resolver_free_node(r, rn);
return;
}
rec = r->connections.elts;
rec = &rec[rn->last_connection];
rn->tcp = 1;
(void) ngx_resolver_send_tcp_query(r, rec, rn->query, rn->qlen);
rn->expire = ngx_time() + r->resend_timeout;
ngx_queue_insert_head(&r->srv_resend_queue, &rn->queue);
return;
}
if (code == 0 && rn->code) {
code = rn->code;
}
if (code == 0 && nan == 0) {
code = NGX_RESOLVE_NXDOMAIN;
}
if (code) {
next = rn->waiting;
rn->waiting = NULL;
ngx_queue_remove(&rn->queue);
ngx_rbtree_delete(&r->srv_rbtree, &rn->node);
while (next) {
ctx = next;
ctx->state = code;
ctx->valid = ngx_time() + (r->valid ? r->valid : 10);
next = ctx->next;
ctx->handler(ctx);
}
ngx_resolver_free_node(r, rn);
return;
}
i = ans;
nsrvs = 0;
cname = NULL;
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 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 in DNS response", class);
goto failed;
}
if (ttl < 0) {
ttl = 0;
}
rn->ttl = ngx_min(rn->ttl, (uint32_t) ttl);
i += sizeof(ngx_resolver_an_t);
switch (type) {
case NGX_RESOLVE_SRV:
if (i + 6 > n) {
goto short_response;
}
if (ngx_resolver_copy(r, NULL, buf, &buf[i + 6], buf + n)
!= NGX_OK)
{
goto failed;
}
nsrvs++;
break;
case NGX_RESOLVE_CNAME:
cname = &buf[i];
break;
case NGX_RESOLVE_DNAME:
break;
default:
ngx_log_error(r->log_level, r->log, 0,
"unexpected RR type %ui in DNS response", type);
}
i += len;
}
ngx_log_debug3(NGX_LOG_DEBUG_CORE, r->log, 0,
"resolver nsrvs:%ui cname:%p ttl:%uD",
nsrvs, cname, rn->ttl);
if (nsrvs) {
srvs = ngx_resolver_calloc(r, nsrvs * sizeof(ngx_resolver_srv_t));
if (srvs == NULL) {
goto failed;
}
rn->u.srvs = srvs;
rn->nsrvs = (u_short) nsrvs;
j = 0;
i = ans;
for (a = 0; a < nan; a++) {
for ( ;; ) {
if (buf[i] & 0xc0) {
i += 2;
break;
}
if (buf[i] == 0) {
i++;
break;
}
i += 1 + buf[i];
}
an = (ngx_resolver_an_t *) &buf[i];
type = (an->type_hi << 8) + an->type_lo;
len = (an->len_hi << 8) + an->len_lo;
i += sizeof(ngx_resolver_an_t);
if (type == NGX_RESOLVE_SRV) {
srvs[j].priority = (buf[i] << 8) + buf[i + 1];
srvs[j].weight = (buf[i + 2] << 8) + buf[i + 3];
if (srvs[j].weight == 0) {
srvs[j].weight = 1;
}
srvs[j].port = (buf[i + 4] << 8) + buf[i + 5];
if (ngx_resolver_copy(r, &srvs[j].name, buf, &buf[i + 6],
buf + n)
!= NGX_OK)
{
goto failed;
}
j++;
}
i += len;
}
ngx_sort(srvs, nsrvs, sizeof(ngx_resolver_srv_t),
ngx_resolver_cmp_srvs);
ngx_resolver_free(r, rn->query);
rn->query = NULL;
ngx_queue_remove(&rn->queue);
rn->valid = ngx_time() + (r->valid ? r->valid : (time_t) rn->ttl);
rn->expire = ngx_time() + r->expire;
ngx_queue_insert_head(&r->srv_expire_queue, &rn->queue);
next = rn->waiting;
rn->waiting = NULL;
while (next) {
ctx = next;
next = ctx->next;
ngx_resolver_resolve_srv_names(ctx, rn);
}
return;
}
rn->nsrvs = 0;
if (cname) {
/* CNAME only */
if (ngx_resolver_copy(r, &name, buf, cname, buf + n) != NGX_OK) {
goto failed;
}
ngx_log_debug1(NGX_LOG_DEBUG_CORE, r->log, 0,
"resolver cname:\"%V\"", &name);
ngx_queue_remove(&rn->queue);
rn->cnlen = (u_short) name.len;
rn->u.cname = name.data;
rn->valid = ngx_time() + (r->valid ? r->valid : (time_t) rn->ttl);
rn->expire = ngx_time() + r->expire;
ngx_queue_insert_head(&r->srv_expire_queue, &rn->queue);
ngx_resolver_free(r, rn->query);
rn->query = NULL;
#if (NGX_HAVE_INET6)
rn->query6 = NULL;
#endif
ctx = rn->waiting;
rn->waiting = NULL;
if (ctx) {
if (ctx->recursion++ >= NGX_RESOLVER_MAX_RECURSION) {
/* unlock name mutex */
do {
ctx->state = NGX_RESOLVE_NXDOMAIN;
next = ctx->next;
ctx->handler(ctx);
ctx = next;
} while (ctx);
return;
}
for (next = ctx; next; next = next->next) {
next->node = NULL;
}
(void) ngx_resolve_name_locked(r, ctx, &name);
}
/* unlock name mutex */
return;
}
ngx_log_error(r->log_level, r->log, 0, "no SRV type in DNS response");
return;
short_response:
err = "short DNS response";
invalid:
/* unlock name mutex */
ngx_log_error(r->log_level, r->log, 0, err);
return;
failed:
/* unlock name mutex */
return;
}
static void
ngx_resolver_resolve_srv_names(ngx_resolver_ctx_t *ctx, ngx_resolver_node_t *rn)
{
ngx_uint_t i;
ngx_resolver_t *r;
ngx_resolver_ctx_t *cctx;
ngx_resolver_srv_name_t *srvs;
r = ctx->resolver;
ctx->node = NULL;
ctx->state = NGX_OK;
ctx->valid = rn->valid;
ctx->count = rn->nsrvs;
srvs = ngx_resolver_calloc(r, rn->nsrvs * sizeof(ngx_resolver_srv_name_t));
if (srvs == NULL) {
goto failed;
}
ctx->srvs = srvs;
ctx->nsrvs = rn->nsrvs;
if (ctx->event && ctx->event->timer_set) {
ngx_del_timer(ctx->event);
}
for (i = 0; i < (ngx_uint_t) rn->nsrvs; i++) {
srvs[i].name.data = ngx_resolver_alloc(r, rn->u.srvs[i].name.len);
if (srvs[i].name.data == NULL) {
goto failed;
}
srvs[i].name.len = rn->u.srvs[i].name.len;
ngx_memcpy(srvs[i].name.data, rn->u.srvs[i].name.data,
srvs[i].name.len);
cctx = ngx_resolve_start(r, NULL);
if (cctx == NULL) {
goto failed;
}
cctx->name = srvs[i].name;
cctx->handler = ngx_resolver_srv_names_handler;
cctx->data = ctx;
cctx->srvs = &srvs[i];
cctx->timeout = ctx->timeout;
srvs[i].priority = rn->u.srvs[i].priority;
srvs[i].weight = rn->u.srvs[i].weight;
srvs[i].port = rn->u.srvs[i].port;
srvs[i].ctx = cctx;
if (ngx_resolve_name(cctx) == NGX_ERROR) {
srvs[i].ctx = NULL;
goto failed;
}
}
return;
failed:
ctx->state = NGX_ERROR;
ctx->valid = ngx_time() + (r->valid ? r->valid : 10);
ctx->handler(ctx);
}
static void
ngx_resolver_srv_names_handler(ngx_resolver_ctx_t *cctx)
{
ngx_uint_t i;
ngx_addr_t *addrs;
ngx_resolver_t *r;
ngx_sockaddr_t *sockaddr;
ngx_resolver_ctx_t *ctx;
ngx_resolver_srv_name_t *srv;
r = cctx->resolver;
ctx = cctx->data;
srv = cctx->srvs;
ctx->count--;
ctx->async |= cctx->async;
srv->ctx = NULL;
srv->state = cctx->state;
if (cctx->naddrs) {
ctx->valid = ngx_min(ctx->valid, cctx->valid);
addrs = ngx_resolver_calloc(r, cctx->naddrs * sizeof(ngx_addr_t));
if (addrs == NULL) {
srv->state = NGX_ERROR;
goto done;
}
sockaddr = ngx_resolver_alloc(r, cctx->naddrs * sizeof(ngx_sockaddr_t));
if (sockaddr == NULL) {
ngx_resolver_free(r, addrs);
srv->state = NGX_ERROR;
goto done;
}
for (i = 0; i < cctx->naddrs; i++) {
addrs[i].sockaddr = &sockaddr[i].sockaddr;
addrs[i].socklen = cctx->addrs[i].socklen;
ngx_memcpy(&sockaddr[i], cctx->addrs[i].sockaddr,
addrs[i].socklen);
ngx_inet_set_port(addrs[i].sockaddr, srv->port);
}
srv->addrs = addrs;
srv->naddrs = cctx->naddrs;
}
done:
ngx_resolve_name_done(cctx);
if (ctx->count == 0) {
ngx_resolver_report_srv(r, ctx);
}
}
static void
ngx_resolver_process_ptr(ngx_resolver_t *r, u_char *buf, size_t n,
ngx_uint_t ident, ngx_uint_t code, ngx_uint_t nan)
{
char *err;
size_t len;
in_addr_t addr;
int32_t ttl;
ngx_int_t octet;
ngx_str_t name;
ngx_uint_t mask, type, class, qident, a, i, start;
ngx_queue_t *expire_queue;
ngx_rbtree_t *tree;
ngx_resolver_an_t *