Add SourceAddr support (#32)

* Add RemoteAddr support

* use SourceAddr

handler/api/api.go

@@ -121,6 +121,9 @@ type Request interface {
 	// Headers allows access to any incoming request headers.
 	Headers() Header
 
+	// GetSourceAddr returns client SourceAddr.
+	GetSourceAddr() string
+
 	// Body allows access to any incoming request body. To read this without
 	// preventing the Next from reading it, enable FeatureBufferRequest.
 	Body() Body

handler/internal/imports/host.go

@@ -178,3 +178,7 @@ func GetStatusCode() uint32 {
 func SetStatusCode(statusCode uint32) {
 	setStatusCode(statusCode)
 }
+
+func GetSourceAddr(ptr uint32, limit BufLimit) (len uint32) {
+	return getSourceAddr(ptr, limit)
+}

handler/internal/imports/imports.go

@@ -57,3 +57,6 @@ func getStatusCode() uint32
 
 //go:wasmimport http_handler set_status_code
 func setStatusCode(statusCode uint32)
+
+//go:wasmimport http_handler get_source_addr
+func getSourceAddr(ptr uint32, limit BufLimit) (len uint32)

handler/internal/imports/imports_stub.go

@@ -77,3 +77,8 @@ func getStatusCode() uint32 {
 
 // setStatusCode is stubbed for compilation outside TinyGo.
 func setStatusCode(statusCode uint32) {}
+
+// getSourceAddr is stubbed for compilation outside TinyGo.
+func getSourceAddr(ptr uint32, limit BufLimit) (len uint32) {
+	return 0
+}

handler/request.go

@@ -57,3 +57,8 @@ func (wasmRequest) Body() api.Body {
 func (wasmRequest) Trailers() api.Header {
 	return wasmRequestTrailers
 }
+
+// GetSourceAddr implements the same method as documented on api.Request.
+func (wasmRequest) GetSourceAddr() string {
+	return mem.GetString(imports.GetSourceAddr)
+}