add domain whois/dns support, refactor codebase

internal/server/utils.go

@@ -0,0 +1,43 @@
+package server
+
+import (
+	"net"
+	"net/http"
+	"strings"
+
+	"ipinfo/internal/common"
+)
+
+// fieldMap maps request fields to their corresponding data struct fields.
+var fieldMap = map[string]func(*common.DataStruct) *string{
+	"ip":       func(d *common.DataStruct) *string { return d.IP },
+	"hostname": func(d *common.DataStruct) *string { return d.Hostname },
+	"org":      func(d *common.DataStruct) *string { return d.Org },
+	"city":     func(d *common.DataStruct) *string { return d.City },
+	"region":   func(d *common.DataStruct) *string { return d.Region },
+	"country":  func(d *common.DataStruct) *string { return d.Country },
+	"timezone": func(d *common.DataStruct) *string { return d.Timezone },
+	"loc":      func(d *common.DataStruct) *string { return d.Loc },
+}
+
+// getField retrieves the value of a specific field from the data struct.
+func getField(data *common.DataStruct, field string) *string {
+	if f, ok := fieldMap[field]; ok {
+		return f(data)
+	}
+	return nil
+}
+
+// GetRealIP extracts the client's real IP address from request headers.
+func GetRealIP(r *http.Request) string {
+	for _, header := range []string{"CF-Connecting-IP", "X-Real-IP", "X-Forwarded-For"} {
+		if ip := r.Header.Get(header); ip != "" {
+			return strings.TrimSpace(strings.Split(ip, ",")[0])
+		}
+	}
+	host, _, err := net.SplitHostPort(r.RemoteAddr)
+	if err != nil {
+		return r.RemoteAddr
+	}
+	return host
+}