nghttpx: Add --dns-lookup-timeout and --dns-max-try options

gennghttpxfun.py

@@ -150,6 +150,8 @@ OPTIONS = [
     "tls-sct-dir",
     "backend-connect-timeout",
     "dns-cache-timeout",
+    "dns-lookup-timeout",
+    "dns-max-try",
 ]
 
 LOGVARS = [

src/shrpx.cc

@@ -1491,7 +1491,9 @@ void fill_default_config(Config *config) {
   {
     auto &timeoutconf = dnsconf.timeout;
     timeoutconf.cache = 10_s;
+    timeoutconf.lookup = 5_s;
   }
+  dnsconf.max_try = 2;
 }
 
 } // namespace
@@ -2388,6 +2390,18 @@ DNS:
               that nghttpx caches the unsuccessful results as well.
               Default: )"
       << util::duration_str(config->dns.timeout.cache) << R"(
+  --dns-lookup-timeout=<DURATION>
+              Set timeout that  DNS server is given to  respond to the
+              initial  DNS  query.  For  the  2nd  and later  queries,
+              server is  given time based  on this timeout, and  it is
+              scaled linearly.
+              Default: )"
+      << util::duration_str(config->dns.timeout.lookup) << R"(
+  --dns-max-try=<N>
+              Set the number of DNS query before nghttpx gives up name
+              lookup.
+              Default: )"
+      << config->dns.max_try << R"(
 
 Debug:
   --frontend-http2-dump-request-header=<PATH>
@@ -3049,6 +3063,8 @@ int main(int argc, char **argv) {
         {SHRPX_OPT_BACKEND_CONNECT_TIMEOUT.c_str(), required_argument, &flag,
          142},
         {SHRPX_OPT_DNS_CACHE_TIMEOUT.c_str(), required_argument, &flag, 143},
+        {SHRPX_OPT_DNS_LOOKUP_TIMEOUT.c_str(), required_argument, &flag, 144},
+        {SHRPX_OPT_DNS_MAX_TRY.c_str(), required_argument, &flag, 145},
         {nullptr, 0, nullptr, 0}};
 
     int option_index = 0;
@@ -3726,6 +3742,14 @@ int main(int argc, char **argv) {
         // --dns-cache-timeout
         cmdcfgs.emplace_back(SHRPX_OPT_DNS_CACHE_TIMEOUT, StringRef{optarg});
         break;
+      case 144:
+        // --dns-lookup-timeou
+        cmdcfgs.emplace_back(SHRPX_OPT_DNS_LOOKUP_TIMEOUT, StringRef{optarg});
+        break;
+      case 145:
+        // --dns-max-try
+        cmdcfgs.emplace_back(SHRPX_OPT_DNS_MAX_TRY, StringRef{optarg});
+        break;
       default:
         break;
       }

src/shrpx_config.cc

@@ -1370,6 +1370,9 @@ int option_lookup_token(const char *name, size_t namelen) {
       }
       break;
     case 'y':
+      if (util::strieq_l("dns-max-tr", name, 10)) {
+        return SHRPX_OPTID_DNS_MAX_TRY;
+      }
       if (util::strieq_l("http2-prox", name, 10)) {
         return SHRPX_OPTID_HTTP2_PROXY;
       }
@@ -1548,6 +1551,9 @@ int option_lookup_token(const char *name, size_t namelen) {
       }
       break;
     case 't':
+      if (util::strieq_l("dns-lookup-timeou", name, 17)) {
+        return SHRPX_OPTID_DNS_LOOKUP_TIMEOUT;
+      }
       if (util::strieq_l("worker-write-burs", name, 17)) {
         return SHRPX_OPTID_WORKER_WRITE_BURST;
       }
@@ -3104,6 +3110,22 @@ int parse_config(Config *config, int optid, const StringRef &opt,
 #endif // !(!LIBRESSL_IN_USE && OPENSSL_VERSION_NUMBER >= 0x10002000L)
   case SHRPX_OPTID_DNS_CACHE_TIMEOUT:
     return parse_duration(&config->dns.timeout.cache, opt, optarg);
+  case SHRPX_OPTID_DNS_LOOKUP_TIMEOUT:
+    return parse_duration(&config->dns.timeout.lookup, opt, optarg);
+  case SHRPX_OPTID_DNS_MAX_TRY: {
+    int n;
+    if (parse_uint(&n, opt, optarg) != 0) {
+      return -1;
+    }
+
+    if (n > 5) {
+      LOG(ERROR) << opt << ": must be smaller than or equal to 5";
+      return -1;
+    }
+
+    config->dns.max_try = n;
+    return 0;
+  }
   case SHRPX_OPTID_CONF:
     LOG(WARN) << "conf: ignored";
 

src/shrpx_config.h

@@ -314,6 +314,9 @@ constexpr auto SHRPX_OPT_BACKEND_CONNECT_TIMEOUT =
     StringRef::from_lit("backend-connect-timeout");
 constexpr auto SHRPX_OPT_DNS_CACHE_TIMEOUT =
     StringRef::from_lit("dns-cache-timeout");
+constexpr auto SHRPX_OPT_DNS_LOOKUP_TIMEOUT =
+    StringRef::from_lit("dns-lookup-timeout");
+constexpr auto SHRPX_OPT_DNS_MAX_TRY = StringRef::from_lit("dns-max-try");
 
 constexpr size_t SHRPX_OBFUSCATED_NODE_LENGTH = 8;
 
@@ -785,7 +788,11 @@ struct APIConfig {
 struct DNSConfig {
   struct {
     ev_tstamp cache;
+    ev_tstamp lookup;
   } timeout;
+  // The number of tries name resolver makes before abandoning
+  // request.
+  size_t max_try;
 };
 
 struct Config {
@@ -905,6 +912,8 @@ enum {
   SHRPX_OPTID_DAEMON,
   SHRPX_OPTID_DH_PARAM_FILE,
   SHRPX_OPTID_DNS_CACHE_TIMEOUT,
+  SHRPX_OPTID_DNS_LOOKUP_TIMEOUT,
+  SHRPX_OPTID_DNS_MAX_TRY,
   SHRPX_OPTID_ECDH_CURVES,
   SHRPX_OPTID_ERROR_PAGE,
   SHRPX_OPTID_ERRORLOG_FILE,

src/shrpx_dns_resolver.cc

@@ -29,6 +29,7 @@
 
 #include "shrpx_log.h"
 #include "shrpx_connection.h"
+#include "shrpx_config.h"
 
 namespace shrpx {
 
@@ -145,11 +146,15 @@ int DNSResolver::resolve(const StringRef &name, int family) {
 
   int rv;
 
+  auto &dnsconf = get_config()->dns;
+
   ares_options opts{};
   opts.sock_state_cb = sock_state_cb;
   opts.sock_state_cb_data = this;
+  opts.timeout = static_cast<int>(dnsconf.timeout.lookup * 1000);
+  opts.tries = dnsconf.max_try;
 
-  auto optmask = ARES_OPT_SOCK_STATE_CB;
+  auto optmask = ARES_OPT_SOCK_STATE_CB | ARES_OPT_TIMEOUTMS | ARES_OPT_TRIES;
 
   ares_channel chan;
   rv = ares_init_options(&chan, &opts, optmask);