feat: add cors support

.env.sample

@@ -1,5 +1,4 @@
 SERVER_WEBSOCKET_PORT="8080"
-SERVER_WEBSOCKET_CHECK_ORIGIN="true"
 SERVER_WEBSOCKET_MAX_CONN="30000"
 SERVER_WEBSOCKET_READ_BUFFER_SIZE="10240"
 SERVER_WEBSOCKET_WRITE_BUFFER_SIZE="10240"
@@ -8,6 +7,13 @@ SERVER_WEBSOCKET_PING_INTERVAL_MS=30000
 SERVER_WEBSOCKET_PONG_WAIT_INTERVAL_MS=60000
 SERVER_WEBSOCKET_WRITE_WAIT_INTERVAL_MS=5000
 SERVER_WEBSOCKET_PINGER_SIZE=1
+SERVER_WEBSOCKET_CHECK_ORIGIN="true"
+
+SERVER_CORS_ENABLED="true"
+SERVER_CORS_ALLOWED_ORIGIN="http://localhost:3000 http://localhost:8080"
+SERVER_CORS_ALLOWED_METHODS="GET HEAD POST OPTIONS"
+SERVER_CORS_PREFLIGHT_MAX_AGE_SECONDS=60
+SERVER_CORS_ALLOWED_HEADERS=""
 
 SERVER_GRPC_PORT=8081
 

.env.test

@@ -1,5 +1,4 @@
 SERVER_WEBSOCKET_PORT="8080"
-SERVER_WEBSOCKET_CHECK_ORIGIN="true"
 SERVER_WEBSOCKET_MAX_CONN="30000"
 SERVER_WEBSOCKET_READ_BUFFER_SIZE="10240"
 SERVER_WEBSOCKET_WRITE_BUFFER_SIZE="10240"
@@ -9,9 +8,16 @@ SERVER_WEBSOCKET_PING_INTERVAL_MS=10000
 SERVER_WEBSOCKET_PONG_WAIT_INTERVAL_MS=10000
 SERVER_WEBSOCKET_WRITE_WAIT_INTERVAL_MS=1000
 SERVER_WEBSOCKET_PINGER_SIZE=1
+SERVER_WEBSOCKET_CHECK_ORIGIN="true"
 
 SERVER_GRPC_PORT=8081
 
+
+SERVER_CORS_ENABLED="true"
+SERVER_CORS_ALLOWED_ORIGIN="http://localhost:3000 http://localhost:8080"
+SERVER_CORS_ALLOWED_METHODS="GET HEAD POST OPTIONS"
+SERVER_CORS_PREFLIGHT_MAX_AGE_SECONDS=60
+
 WORKER_BUFFER_CHANNEL_SIZE=5
 WORKER_BUFFER_FLUSH_TIMEOUT_MS=5000
 WORKER_POOL_SIZE=5

.gitignore

@@ -15,3 +15,4 @@ coverage
 *.idea/
 raccoon
 .temp
+__debug.*

config/load.go

@@ -25,6 +25,7 @@ func Load() {
 	serverConfigLoader()
 	serverWsConfigLoader()
 	serverGRPCConfigLoader()
+	serverCorsConfigLoader()
 	workerConfigLoader()
 	metricStatsdConfigLoader()
 	eventDistributionConfigLoader()

config/server.go

@@ -10,6 +10,7 @@ import (
 var Server server
 var ServerWs serverWs
 var ServerGRPC serverGRPC
+var ServerCors serverCors
 
 type server struct {
 	DedupEnabled bool
@@ -20,33 +21,79 @@ type serverWs struct {
 	ServerMaxConn     int
 	ReadBufferSize    int
 	WriteBufferSize   int
-	CheckOrigin       bool
 	PingInterval      time.Duration
 	PongWaitInterval  time.Duration
 	WriteWaitInterval time.Duration
 	PingerSize        int
 	ConnIDHeader      string
 	ConnGroupHeader   string
 	ConnGroupDefault  string
+	CheckOrigin       bool
 }
 
 type serverGRPC struct {
 	Port string
 }
 
+type serverCors struct {
+	Enabled          bool
+	AllowedOrigin    []string
+	AllowedMethods   []string
+	AllowedHeaders   []string
+	AllowCredentials bool
+	MaxAge           int
+}
+
 func serverConfigLoader() {
 	viper.SetDefault("SERVER_BATCH_DEDUP_IN_CONNECTION_ENABLED", "false")
 	Server = server{
 		DedupEnabled: util.MustGetBool("SERVER_BATCH_DEDUP_IN_CONNECTION_ENABLED"),
 	}
 }
 
+func serverCorsConfigLoader() {
+	viper.SetDefault("SERVER_CORS_ENABLED", false)
+	viper.SetDefault("SERVER_CORS_ALLOWED_ORIGIN", "")
+	viper.SetDefault("SERVER_CORS_ALLOWED_METHODS", []string{"GET", "HEAD", "POST", "OPTIONS"})
+	viper.SetDefault("SERVER_CORS_ALLOWED_HEADERS", "")
+	viper.SetDefault("SERVER_CORS_ALLOW_CREDENTIALS", false)
+	viper.SetDefault("SERVER_CORS_PREFLIGHT_MAX_AGE_SECONDS", 0)
+	ServerCors = serverCors{
+		Enabled:          util.MustGetBool("SERVER_CORS_ENABLED"),
+		AllowedOrigin:    viper.GetStringSlice("SERVER_CORS_ALLOWED_ORIGIN"),
+		AllowedMethods:   viper.GetStringSlice("SERVER_CORS_ALLOWED_METHODS"),
+		AllowCredentials: util.MustGetBool("SERVER_CORS_ALLOW_CREDENTIALS"),
+		AllowedHeaders:   getAllowedHeaders(),
+		MaxAge:           util.MustGetInt("SERVER_CORS_PREFLIGHT_MAX_AGE_SECONDS"),
+	}
+}
+
+func getAllowedHeaders() []string {
+	allowedHeaders := []string{"Content-Type"}
+	allowedHeaders = setAllowedHeaders(allowedHeaders, "SERVER_WEBSOCKET_CONN_GROUP_HEADER")
+	allowedHeaders = setAllowedHeaders(allowedHeaders, "SERVER_WEBSOCKET_CONN_ID_HEADER")
+	inputHeaders := viper.GetStringSlice("SERVER_CORS_ALLOWED_HEADERS")
+	for _, input := range inputHeaders {
+		if input != "" && !util.Contains(input, allowedHeaders) {
+			allowedHeaders = append(allowedHeaders, input)
+		}
+	}
+	return allowedHeaders
+}
+
+func setAllowedHeaders(allowedHeaders []string, envKey string) []string {
+	if header := viper.GetString(envKey); header != "" {
+		allowedHeaders = append(allowedHeaders, header)
+	}
+	return allowedHeaders
+}
+
 func serverWsConfigLoader() {
+	viper.SetDefault("SERVER_WEBSOCKET_CHECK_ORIGIN", true)
 	viper.SetDefault("SERVER_WEBSOCKET_PORT", "8080")
 	viper.SetDefault("SERVER_WEBSOCKET_MAX_CONN", 30000)
 	viper.SetDefault("SERVER_WEBSOCKET_READ_BUFFER_SIZE", 10240)
 	viper.SetDefault("SERVER_WEBSOCKET_WRITE_BUFFER_SIZE", 10240)
-	viper.SetDefault("SERVER_WEBSOCKET_CHECK_ORIGIN", true)
 	viper.SetDefault("SERVER_WEBSOCKET_PING_INTERVAL_MS", "30000")
 	viper.SetDefault("SERVER_WEBSOCKET_PONG_WAIT_INTERVAL_MS", "60000") //should be more than the ping period
 	viper.SetDefault("SERVER_WEBSOCKET_WRITE_WAIT_INTERVAL_MS", "5000")
@@ -59,14 +106,14 @@ func serverWsConfigLoader() {
 		ServerMaxConn:     util.MustGetInt("SERVER_WEBSOCKET_MAX_CONN"),
 		ReadBufferSize:    util.MustGetInt("SERVER_WEBSOCKET_READ_BUFFER_SIZE"),
 		WriteBufferSize:   util.MustGetInt("SERVER_WEBSOCKET_WRITE_BUFFER_SIZE"),
-		CheckOrigin:       util.MustGetBool("SERVER_WEBSOCKET_CHECK_ORIGIN"),
 		PingInterval:      util.MustGetDuration("SERVER_WEBSOCKET_PING_INTERVAL_MS", time.Millisecond),
 		PongWaitInterval:  util.MustGetDuration("SERVER_WEBSOCKET_PONG_WAIT_INTERVAL_MS", time.Millisecond),
 		WriteWaitInterval: util.MustGetDuration("SERVER_WEBSOCKET_WRITE_WAIT_INTERVAL_MS", time.Millisecond),
 		PingerSize:        util.MustGetInt("SERVER_WEBSOCKET_PINGER_SIZE"),
 		ConnIDHeader:      util.MustGetString("SERVER_WEBSOCKET_CONN_ID_HEADER"),
 		ConnGroupHeader:   util.MustGetString("SERVER_WEBSOCKET_CONN_GROUP_HEADER"),
 		ConnGroupDefault:  util.MustGetString("SERVER_WEBSOCKET_CONN_GROUP_DEFAULT"),
+		CheckOrigin:       util.MustGetBool("SERVER_WEBSOCKET_CHECK_ORIGIN"),
 	}
 }
 

config/util/key.go

@@ -37,3 +37,14 @@ func mustHave(key string) {
 		panic(fmt.Sprintf("key %s is not set", key))
 	}
 }
+
+func Contains(key string, slice []string) bool {
+	for _, v := range slice {
+		if v == key {
+			return true
+		}
+	}
+
+	return false
+
+}

docs/docs/reference/configurations.md

@@ -97,6 +97,48 @@ Toggle CORS check function. Set `true` to check each request origin. Set `false`
 - Type: `Optional`
 - Default value: `true`
 
+### `SERVER_CORS_ENABLED`
+
+The config decides whether to enable the cors middleware and thus allow CORS requests. This config only enables CORS for rest services. For websocket, refer `SERVER_WEBSOCKET_CHECK_ORIGIN`
+
+- Type `Optional`
+- Default value: `false`
+
+### `SERVER_CORS_ALLOWED_ORIGIN`
+
+The server decides which origin to allow. The configuration is expected to space separated. Multiple values are supported. The value requies `SERVER_CORS_ENABLED` to be true to take effect. If you want to allow all host headers. You can pass `*` as the value.
+
+- Type `Optional`
+- Default Value ``
+
+### `SERVER_CORS_ALLOWED_METHODS`
+
+The http methods allowed when it's a cross origin request. The http methods are expected to be space separated. 
+
+- Type `Optional`
+- Default Value `GET HEAD POST OPTIONS`
+
+### `SERVER_CORS_ALLOWED_HEADERS`
+
+The http request headers which are allowed when request is cross origin. The input expects to add any additional headers which is going to be sent by the client ex: `Authorization`. Headers which are essential for the functioning of Raccoon like Content-Type, Connection-Id & Group headers are added by default and need not be passed as configuration.
+
+- Type `Optional`
+- Default Value ``
+
+### `SERVER_CORS_ALLOW_CREDENTIALS`
+
+AllowCredentials can be used to specify that the user agent may pass authentication details along with the request. 
+
+- Type `Optional`
+- Default Value `false`
+
+### `SERVER_CORS_PREFLIGHT_MAX_AGE_SECONDS`
+
+Replies with a header for clients on how long to cache the response of the preflight request. It's not enforceable. The max value is 600s
+
+- Type `Optional`
+- Default Value `0`
+
 ### `SERVER_BATCH_DEDUP_IN_CONNECTION_ENABLED`
 
 The server decides whether or not to handle duplicate batches for the active connection. If a batch is sent with a duplicate ReqGUID, the server uses best attempts to discard the duplicate batches. Set `true` to enable the setting.

go.mod

@@ -4,6 +4,7 @@ go 1.14
 
 require (
 	github.com/confluentinc/confluent-kafka-go v1.9.3-RC3
+	github.com/gorilla/handlers v1.5.1
 	github.com/gorilla/mux v1.7.4
 	github.com/gorilla/websocket v1.4.2
 	github.com/sirupsen/logrus v1.6.0

go.sum

@@ -62,6 +62,8 @@ github.com/envoyproxy/go-control-plane v0.9.9-0.20210217033140-668b12f5399d/go.m
 github.com/envoyproxy/go-control-plane v0.10.2-0.20220325020618-49ff273808a1/go.mod h1:KJwIaB5Mv44NWtYuAOFCVOjcI94vtpEz2JU/D2v6IjE=
 github.com/envoyproxy/protoc-gen-validate v0.1.0/go.mod h1:iSmxcyjqTsJpI2R4NaDN7+kN2VEUnK/pcBlmesArF7c=
 github.com/fatih/color v1.7.0/go.mod h1:Zm6kSWBoL9eyXnKyktHP6abPY2pDugNf5KwzbycvMj4=
+github.com/felixge/httpsnoop v1.0.1 h1:lvB5Jl89CsZtGIWuTcDM1E/vkVs49/Ml7JJe07l8SPQ=
+github.com/felixge/httpsnoop v1.0.1/go.mod h1:m8KPJKqk1gH5J9DgRY2ASl2lWCfGKXixSwevea8zH2U=
 github.com/frankban/quicktest v1.2.2/go.mod h1:Qh/WofXFeiAFII1aEBu529AtJo6Zg2VHscnEsbBnJ20=
 github.com/frankban/quicktest v1.7.2/go.mod h1:jaStnuzAqU1AJdCO0l53JDCJrVDKcS03DbaAcR7Ks/o=
 github.com/frankban/quicktest v1.10.0/go.mod h1:ui7WezCLWMWxVWr1GETZY3smRy0G4KWq9vcPtJmFl7Y=
@@ -122,6 +124,8 @@ github.com/googleapis/gax-go/v2 v2.0.4/go.mod h1:0Wqv26UfaUD9n4G6kQubkQ+KchISgw+
 github.com/googleapis/gax-go/v2 v2.0.5/go.mod h1:DWXyrwAJ9X0FpwwEdw+IPEYBICEFu5mhpdKc/us6bOk=
 github.com/gopherjs/gopherjs v0.0.0-20181017120253-0766667cb4d1 h1:EGx4pi6eqNxGaHF6qqu48+N2wcFQ5qg5FXgOdqsJ5d8=
 github.com/gopherjs/gopherjs v0.0.0-20181017120253-0766667cb4d1/go.mod h1:wJfORRmW1u3UXTncJ5qlYoELFm8eSnnEO6hX4iZ3EWY=
+github.com/gorilla/handlers v1.5.1 h1:9lRY6j8DEeeBT10CvO9hGW0gmky0BprnvDI5vfhUHH4=
+github.com/gorilla/handlers v1.5.1/go.mod h1:t8XrUpc4KVXb7HGyJ4/cEnwQiaxrX/hz1Zv/4g96P1Q=
 github.com/gorilla/mux v1.7.4 h1:VuZ8uybHlWmqV03+zRzdwKL4tUnIp1MAQtp1mIFE1bc=
 github.com/gorilla/mux v1.7.4/go.mod h1:DVbg23sWSpFRCP0SfiEN6jmj59UnW/n46BH5rLB71So=
 github.com/gorilla/websocket v1.4.2 h1:+/TMaTYc4QFitKJxsQ7Yye35DkWvkdLcvGKqM+x0Ufc=