static ngx_int_t
ngx_resolve_name_locked(ngx_resolver_t *r, ngx_resolver_ctx_t *ctx)
{
uint32_t hash;
in_addr_t addr, *addrs;
ngx_int_t rc;
ngx_uint_t naddrs;
ngx_resolver_ctx_t *next;
ngx_resolver_node_t *rn;
hash = ngx_crc32_short(ctx->name.data, ctx->name.len);
rn = ngx_resolver_lookup_name(r, &ctx->name, hash);
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(&r->name_expire_queue, &rn->queue);
naddrs = rn->naddrs;
if (naddrs) {
/* NGX_RESOLVE_A answer */
if (naddrs != 1) {
addr = 0;
addrs = ngx_resolver_dup(r, rn->u.addrs,
naddrs * sizeof(in_addr_t));
if (addrs == NULL) {
return NGX_ERROR;
}
} else {
addr = rn->u.addr;
addrs = NULL;
}
ctx->next = rn->waiting;
rn->waiting = NULL;
/* unlock name mutex */
do {
ctx->state = NGX_OK;
ctx->naddrs = naddrs;
ctx->addrs = (naddrs == 1) ? &ctx->addr : addrs;
ctx->addr = addr;
next = ctx->next;
ctx->handler(ctx);
ctx = next;
} while (ctx);
if (addrs) {
ngx_resolver_free(r, addrs);
}
return NGX_OK;
}
/* NGX_RESOLVE_CNAME */
if (ctx->recursion++ < NGX_RESOLVER_MAX_RECURSION) {
ctx->name.len = rn->cnlen;
ctx->name.data = rn->u.cname;
return ngx_resolve_name_locked(r, ctx);
}
ctx->next = rn->waiting;
rn->waiting = NULL;
/* unlock name mutex */
do {
ctx->state = NGX_RESOLVE_NXDOMAIN;
next = ctx->next;
ctx->handler(ctx);
ctx = next;
} while (ctx);
return NGX_OK;
}
if (rn->waiting) {
ctx->next = rn->waiting;
rn->waiting = ctx;
ctx->state = NGX_AGAIN;
return NGX_AGAIN;
}
ngx_queue_remove(&rn->queue);
/* lock alloc mutex */
ngx_resolver_free_locked(r, rn->query);
rn->query = NULL;
if (rn->cnlen) {
ngx_resolver_free_locked(r, rn->u.cname);
}
if (rn->naddrs > 1) {
ngx_resolver_free_locked(r, rn->u.addrs);
}
/* 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, ctx->name.data, ctx->name.len);
if (rn->name == NULL) {
ngx_resolver_free(r, rn);
return NGX_ERROR;
}
rn->node.key = hash;
rn->nlen = (u_short) ctx->name.len;
rn->query = NULL;
ngx_rbtree_insert(&r->name_rbtree, &rn->node);
}
rc = ngx_resolver_create_name_query(rn, ctx);
if (rc == NGX_ERROR) {
goto failed;
}
if (rc == NGX_DECLINED) {
ngx_rbtree_delete(&r->name_rbtree, &rn->node);
ngx_resolver_free(r, rn->query);
ngx_resolver_free(r, rn->name);
ngx_resolver_free(r, rn);
ctx->state = NGX_RESOLVE_NXDOMAIN;
ctx->handler(ctx);
return NGX_OK;
}
if (ngx_resolver_send_query(r, rn) != NGX_OK) {
goto failed;
}
if (ctx->event == NULL) {
ctx->event = ngx_resolver_calloc(r, sizeof(ngx_event_t));
if (ctx->event == NULL) {
goto failed;
}
ctx->event->handler = ngx_resolver_timeout_handler;
ctx->event->data = ctx;
ctx->event->log = r->log;
ctx->ident = -1;
ngx_add_timer(ctx->event, ctx->timeout);
}
if (ngx_queue_empty(&r->name_resend_queue)) {
ngx_add_timer(r->event, (ngx_msec_t) (r->resend_timeout * 1000));
}
rn->expire = ngx_time() + r->resend_timeout;
ngx_queue_insert_head(&r->name_resend_queue, &rn->queue);
rn->cnlen = 0;
rn->naddrs = 0;
rn->valid = 0;
rn->waiting = ctx;
ctx->state = NGX_AGAIN;
return NGX_AGAIN;
failed:
ngx_rbtree_delete(&r->name_rbtree, &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;
}
static void
ngx_resolver_process_a(ngx_resolver_t *r, u_char *buf, size_t last,
ngx_uint_t ident, ngx_uint_t code, ngx_uint_t nan, ngx_uint_t ans)
{
char *err;
u_char *cname;
size_t len;
int32_t ttl;
uint32_t hash;
in_addr_t addr, *addrs;
ngx_str_t name;
ngx_uint_t qtype, qident, naddrs, a, i, n, start;
ngx_resolver_an_t *an;
ngx_resolver_ctx_t *ctx, *next;
ngx_resolver_node_t *rn;
if (ngx_resolver_copy(r, &name, buf, &buf[12], &buf[last]) != 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 || rn->query == NULL) {
ngx_log_error(r->log_level, r->log, 0,
"unexpected response for %V", &name);
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 response for %V, expect %ui",
ident, &name, qident);
goto failed;
}
ngx_resolver_free(r, name.data);
if (code == 0 && nan == 0) {
code = 3; /* NXDOMAIN */
}
if (code) {
next = rn->waiting;
rn->waiting = NULL;
ngx_queue_remove(&rn->queue);
ngx_rbtree_delete(&r->name_rbtree, &rn->node);
ngx_resolver_free_node(r, rn);
/* unlock name mutex */
while (next) {
ctx = next;
ctx->state = code;
next = ctx->next;
ctx->handler(ctx);
}
return;
}
i = ans;
naddrs = 0;
addr = 0;
addrs = NULL;
cname = NULL;
qtype = 0;
ttl = 0;
for (a = 0; a < nan; a++) {
start = i;
while (i < last) {
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) >= last) {
goto short_response;
}
an = (ngx_resolver_an_t *) &buf[i];
qtype = (an->type_hi << 8) + an->type_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 (ttl < 0) {
ttl = 0;
}
if (qtype == NGX_RESOLVE_A) {
i += sizeof(ngx_resolver_an_t);
if (i + len > last) {
goto short_response;
}
addr = htonl((buf[i] << 24) + (buf[i + 1] << 16)
+ (buf[i + 2] << 8) + (buf[i + 3]));
naddrs++;
i += len;
} else if (qtype == NGX_RESOLVE_CNAME) {
cname = &buf[i] + sizeof(ngx_resolver_an_t);
i += sizeof(ngx_resolver_an_t) + len;
} else if (qtype == NGX_RESOLVE_DNAME) {
i += sizeof(ngx_resolver_an_t) + len;
} else {
ngx_log_error(r->log_level, r->log, 0,
"unexpected qtype %ui", qtype);
}
}
ngx_log_debug3(NGX_LOG_DEBUG_CORE, r->log, 0,
"resolver naddrs:%ui cname:%p ttl:%d",
naddrs, cname, ttl);
if (naddrs) {
if (naddrs == 1) {
rn->u.addr = addr;
} else {
addrs = ngx_resolver_alloc(r, naddrs * sizeof(in_addr_t));
if (addrs == NULL) {
return;
}
n = 0;
i = ans;
for (a = 0; a < nan; a++) {
for ( ;; ) {
if (buf[i] & 0xc0) {
i += 2;
goto ok;
}
if (buf[i] == 0) {
i++;
goto ok;
}
i += 1 + buf[i];
}
ok:
an = (ngx_resolver_an_t *) &buf[i];
qtype = (an->type_hi << 8) + an->type_lo;
len = (an->len_hi << 8) + an->len_lo;
i += sizeof(ngx_resolver_an_t);
if (qtype == NGX_RESOLVE_A) {
addrs[n++] = htonl((buf[i] << 24) + (buf[i + 1] << 16)
+ (buf[i + 2] << 8) + (buf[i + 3]));
if (n == naddrs) {
break;
}
}
i += len;
}
rn->u.addrs = addrs;
addrs = ngx_resolver_dup(r, rn->u.addrs,
naddrs * sizeof(in_addr_t));
if (addrs == NULL) {
return;
}
}
rn->naddrs = (u_short) naddrs;
ngx_queue_remove(&rn->queue);
rn->valid = ngx_time() + (r->valid ? r->valid : 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->naddrs = naddrs;
ctx->addrs = (naddrs == 1) ? &ctx->addr : addrs;
ctx->addr = addr;
next = ctx->next;
ctx->handler(ctx);
}
if (naddrs > 1) {
ngx_resolver_free(r, addrs);
}
return;
} else if (cname) {
/* CNAME only */
if (ngx_resolver_copy(r, &name, buf, cname, &buf[last]) != NGX_OK) {
return;
}
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 : ttl);
rn->expire = ngx_time() + r->expire;
ngx_queue_insert_head(&r->name_expire_queue, &rn->queue);
ctx = rn->waiting;
rn->waiting = NULL;
if (ctx) {
ctx->name = name;
(void) ngx_resolve_name_locked(r, ctx);
}
return;
}
ngx_log_error(r->log_level, r->log, 0,
"no A or CNAME types in DNS responses, unknown query type: %ui",
qtype);
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 */
ngx_resolver_free(r, name.data);
return;
}
void
ngx_resolve_name_done(ngx_resolver_ctx_t *ctx)
{
uint32_t hash;
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->state == NGX_AGAIN || ctx->state == NGX_RESOLVE_TIMEDOUT) {
hash = ngx_crc32_short(ctx->name.data, ctx->name.len);
rn = ngx_resolver_lookup_name(r, &ctx->name, hash);
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:
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 */
}
static void ngx_http_upstream_dynamic_server_resolve_handler(ngx_resolver_ctx_t *ctx) {
ngx_http_upstream_dynamic_server_main_conf_t *udsmcf = ngx_http_cycle_get_module_main_conf(ngx_cycle, ngx_http_upstream_dynamic_servers_module);
ngx_http_upstream_dynamic_server_conf_t *dynamic_server;
ngx_conf_t cf;
uint32_t hash;
ngx_resolver_node_t *rn;
ngx_pool_t *new_pool;
ngx_addr_t *addrs;
dynamic_server = ctx->data;
ngx_log_debug(NGX_LOG_DEBUG_CORE, ctx->resolver->log, 0, "upstream-dynamic-servers: Finished resolving '%V'", &ctx->name);
if (ctx->state) {
ngx_log_error(NGX_LOG_ERR, ctx->resolver->log, 0, "upstream-dynamic-servers: '%V' could not be resolved (%i: %s)", &ctx->name, ctx->state, ngx_resolver_strerror(ctx->state));
ngx_url_t u;
ngx_memzero(&u, sizeof(ngx_url_t));
// If the domain fails to resolve on start up, assign a static IP that
// should never route (we'll also mark it as down in the upstream later
// on). This is to account for various things inside nginx that seem to
// expect a server to always have at least 1 IP.
u.url = ngx_http_upstream_dynamic_server_null_route;
u.default_port = 80;
u.no_resolve = 1;
if (ngx_parse_url(ngx_cycle->pool, &u) != NGX_OK) {
if (u.err) {
ngx_log_error(NGX_LOG_ERR, ctx->resolver->log, 0,
"%s in upstream \"%V\"", u.err, &u.url);
}
goto end;
}
ctx->addr.sockaddr = u.addrs[0].sockaddr;
ctx->addr.socklen = u.addrs[0].socklen;
ctx->addr.name = u.addrs[0].name;
ctx->addrs = &ctx->addr;
ctx->naddrs = u.naddrs;
}
if (ctx->naddrs != dynamic_server->server->naddrs) {
goto reinit_upstream;
}
ngx_uint_t i, j, founded;
ngx_addr_t *existing_addr;
for (i = 0; i < ctx->naddrs; i++) {
founded = 0;
for (j = 0; j < ctx->naddrs; j++) {
existing_addr = &dynamic_server->server->addrs[j];
if (ngx_cmp_sockaddr(existing_addr->sockaddr, existing_addr->socklen, ctx->addrs[i].sockaddr, ctx->addrs[i].socklen, 0) == NGX_OK) {
founded = 1;
break;
}
}
if (!founded) {
goto reinit_upstream;
}
}
ngx_log_debug(NGX_LOG_DEBUG_CORE, ctx->resolver->log, 0, "upstream-dynamic-servers: No DNS changes for '%V' - keeping existing upstream configuration", &ctx->name);
goto end;
reinit_upstream:
new_pool = ngx_create_pool(NGX_DEFAULT_POOL_SIZE, ctx->resolver->log);
if (new_pool == NULL) {
ngx_log_error(NGX_LOG_ERR, ctx->resolver->log, 0, "upstream-dynamic-servers: Could not create new pool");
goto end;
}
ngx_log_debug(NGX_LOG_DEBUG_CORE, ctx->resolver->log, 0, "upstream-dynamic-servers: DNS changes for '%V' detected - reinitializing upstream configuration", &ctx->name);
ngx_memzero(&cf, sizeof(ngx_conf_t));
cf.name = "dynamic_server_init_upstream";
cf.cycle = (ngx_cycle_t *) ngx_cycle;
cf.pool = new_pool;
cf.module_type = NGX_HTTP_MODULE;
cf.cmd_type = NGX_HTTP_MAIN_CONF;
cf.log = ngx_cycle->log;
cf.ctx = udsmcf->conf_ctx;
addrs = ngx_pcalloc(new_pool, ctx->naddrs * sizeof(ngx_addr_t));
ngx_memcpy(addrs, ctx->addrs, ctx->naddrs * sizeof(ngx_addr_t));
struct sockaddr *sockaddr;
ngx_addr_t *addr;
socklen_t socklen;
for (i = 0; i < ctx->naddrs; i++) {
addr = &addrs[i];
socklen = ctx->addrs[i].socklen;
sockaddr = ngx_palloc(new_pool, socklen);
ngx_memcpy(sockaddr, ctx->addrs[i].sockaddr, socklen);
switch(sockaddr->sa_family) {
case AF_INET6:
((struct sockaddr_in6 *)sockaddr)->sin6_port = htons((u_short) dynamic_server->port);
break;
default:
((struct sockaddr_in *)sockaddr)->sin_port = htons((u_short) dynamic_server->port);
}
addr->sockaddr = sockaddr;
addr->socklen = socklen;
u_char *p;
size_t len;
p = ngx_pnalloc(new_pool, NGX_SOCKADDR_STRLEN);
if (p == NULL) {
ngx_log_error(NGX_LOG_ERR, ctx->resolver->log, 0, "upstream-dynamic-servers: Error initializing sockaddr");
ngx_destroy_pool(new_pool);
goto end;
}
len = ngx_sock_ntop(sockaddr, socklen, p, NGX_SOCKADDR_STRLEN, 1);
addr->name.len = len;
addr->name.data = p;
ngx_log_debug(NGX_LOG_DEBUG_CORE, ctx->resolver->log, 0, "upstream-dynamic-servers: '%V' was resolved to '%V'", &ctx->name, &addr->name);
}
// If the domain failed to resolve, mark this server as down.
dynamic_server->server->down = ctx->state ? 1 : 0;
dynamic_server->server->addrs = addrs;
dynamic_server->server->naddrs = ctx->naddrs;
ngx_http_upstream_init_pt init;
init = dynamic_server->upstream_conf->peer.init_upstream ? dynamic_server->upstream_conf->peer.init_upstream : ngx_http_upstream_init_round_robin;
if (init(&cf, dynamic_server->upstream_conf) != NGX_OK) {
ngx_log_error(NGX_LOG_ERR, ctx->resolver->log, 0, "upstream-dynamic-servers: Error re-initializing upstream after DNS changes");
}
if (dynamic_server->previous_pool != NULL) {
ngx_destroy_pool(dynamic_server->previous_pool);
dynamic_server->previous_pool = NULL;
}
dynamic_server->previous_pool = dynamic_server->pool;
dynamic_server->pool = new_pool;
end:
if (ctx->resolver->log->log_level & NGX_LOG_DEBUG_CORE) {
hash = ngx_crc32_short(ctx->name.data, ctx->name.len);
rn = ngx_resolver_lookup_name(ctx->resolver, &ctx->name, hash);
uint32_t refresh_in;
if (rn != NULL && rn->ttl) {
refresh_in = (rn->valid - ngx_time()) * 1000;
if (!refresh_in || refresh_in < 1000) {
refresh_in = 1000;
}
} else {
refresh_in = 1000;
}
ngx_log_debug(NGX_LOG_DEBUG_CORE, ctx->resolver->log, 0, "upstream-dynamic-servers: Refreshing DNS of '%V' in %ims", &ctx->name, refresh_in);
}
ngx_resolve_name_done(ctx);
if (ngx_exiting) {
ngx_log_debug(NGX_LOG_DEBUG_CORE, ngx_cycle->log, 0, "upstream-dynamic-servers: worker is about to exit, do not set the timer again");
return;
}
ngx_add_timer(&dynamic_server->timer, 1000);
}
