Config max request header size

config/config.go

@@ -95,6 +95,7 @@ func setConfigDefaults(v *viper.Viper) {
 	v.SetDefault("request_limits.max_size_bytes", utils.REQUEST_MAX_SIZE_BYTES)
 	v.SetDefault("request_limits.max_num_values", utils.REQUEST_MAX_NUM_VALUES)
 	v.SetDefault("request_limits.max_ttl_seconds", utils.REQUEST_MAX_TTL_SECONDS)
+	v.SetDefault("request_limits.max_header_size_bytes", 0)
 	v.SetDefault("routes.allow_public_write", true)
 }
 
@@ -179,6 +180,7 @@ type RequestLimits struct {
 	MaxNumValues     int  `mapstructure:"max_num_values"`
 	MaxTTLSeconds    int  `mapstructure:"max_ttl_seconds"`
 	AllowSettingKeys bool `mapstructure:"allow_setting_keys"`
+	MaxHeaderSize    int  `mapstructure:"max_header_size_bytes"`
 }
 
 func (cfg *RequestLimits) validateAndLog() {
@@ -201,6 +203,12 @@ func (cfg *RequestLimits) validateAndLog() {
 	} else {
 		log.Fatalf("invalid config.request_limits.max_num_values: %d. Value cannot be negative.", cfg.MaxNumValues)
 	}
+
+	if cfg.MaxHeaderSize >= 0 {
+		log.Infof("config.request_limits.max_header_size_bytes: %d", cfg.MaxHeaderSize)
+	} else {
+		log.Fatalf("invalid config.request_limits.max_header_size_bytes: %d. Value cannot be negative.", cfg.MaxHeaderSize)
+	}
 }
 
 type Compression struct {

config/config_test.go

@@ -867,6 +867,18 @@ func TestRequestLimitsValidateAndLog(t *testing.T) {
 			},
 			expectFatal: true,
 		},
+		{
+			description:        "Negative max_num_values, expect fatal level log and early exit",
+			inRequestLimitsCfg: &RequestLimits{MaxHeaderSize: -1},
+			expectedLogInfo: []logComponents{
+				{msg: `config.request_limits.allow_setting_keys: false`, lvl: logrus.InfoLevel},
+				{msg: `config.request_limits.max_ttl_seconds: 0`, lvl: logrus.InfoLevel},
+				{msg: `config.request_limits.max_size_bytes: 0`, lvl: logrus.InfoLevel},
+				{msg: `config.request_limits.max_num_values: 0`, lvl: logrus.InfoLevel},
+				{msg: `invalid config.request_limits.max_header_size_bytes: -1. Value cannot be negative.`, lvl: logrus.FatalLevel},
+			},
+			expectFatal: true,
+		},
 	}
 
 	//substitute logger exit function so execution doesn't get interrupted
@@ -1078,6 +1090,7 @@ func TestConfigurationValidateAndLog(t *testing.T) {
 		{msg: fmt.Sprintf("config.request_limits.max_ttl_seconds: %d", expectedConfig.RequestLimits.MaxTTLSeconds), lvl: logrus.InfoLevel},
 		{msg: fmt.Sprintf("config.request_limits.max_size_bytes: %d", expectedConfig.RequestLimits.MaxSize), lvl: logrus.InfoLevel},
 		{msg: fmt.Sprintf("config.request_limits.max_num_values: %d", expectedConfig.RequestLimits.MaxNumValues), lvl: logrus.InfoLevel},
+		{msg: fmt.Sprintf("config.request_limits.max_header_size_bytes: %d", expectedConfig.RequestLimits.MaxHeaderSize), lvl: logrus.InfoLevel},
 		{msg: fmt.Sprintf("config.backend.type: %s", expectedConfig.Backend.Type), lvl: logrus.InfoLevel},
 		{msg: fmt.Sprintf("config.compression.type: %s", expectedConfig.Compression.Type), lvl: logrus.InfoLevel},
 		{msg: fmt.Sprintf("Prebid Cache will run without metrics"), lvl: logrus.InfoLevel},
@@ -1244,6 +1257,7 @@ func getExpectedFullConfigForTestFile() Configuration {
 			MaxNumValues:     10,
 			MaxTTLSeconds:    5000,
 			AllowSettingKeys: true,
+			MaxHeaderSize:    16384, //16KiB
 		},
 		Backend: Backend{
 			Type: BackendMemory,

config/configtest/sample_full_config.yaml

@@ -11,6 +11,7 @@ request_limits:
   max_num_values: 10
   max_ttl_seconds: 5000
   allow_setting_keys: true
+  max_header_size_bytes: 16384
 backend:
   type: "memory"
   aerospike:

server/server.go

@@ -74,20 +74,37 @@ func Listen(cfg config.Configuration, publicHandler http.Handler, adminHandler h
 	return
 }
 
+// newAdminServer returns an http.Server with the AdminPort and RequestLimits.MaxHeaderBytes
+// from Prebid Cache's config files or environment variables. If RequestLimits.MaxHeaderBytes
+// is zero or was not specified, the http library's DefaultMaxHeaderBytes value of 1 MB
+// is set instead.
 func newAdminServer(cfg config.Configuration, handler http.Handler) *http.Server {
-	return &http.Server{
+	server := &http.Server{
 		Addr:    ":" + strconv.Itoa(cfg.AdminPort),
 		Handler: handler,
 	}
+	if cfg.RequestLimits.MaxHeaderSize > 0 {
+		server.MaxHeaderBytes = cfg.RequestLimits.MaxHeaderSize
+	}
+	return server
 }
 
+// newMainServer returns an http.Server with the configured Port and
+// RequestLimits.MaxHeaderBytes values specified in Prebid Cache's config files
+// or environment variables. If RequestLimits.MaxHeaderBytes is zero or was not
+// specified, 1 MB, which is the value of the http library's DefaultMaxHeaderBytes,
+// is set instead.
 func newMainServer(cfg config.Configuration, handler http.Handler) *http.Server {
-	return &http.Server{
+	server := &http.Server{
 		Addr:         ":" + strconv.Itoa(cfg.Port),
 		Handler:      handler,
 		ReadTimeout:  15 * time.Second,
 		WriteTimeout: 15 * time.Second,
 	}
+	if cfg.RequestLimits.MaxHeaderSize > 0 {
+		server.MaxHeaderBytes = cfg.RequestLimits.MaxHeaderSize
+	}
+	return server
 }
 
 func runServer(server *http.Server, name string, listener net.Listener) {