feat(core): 添加IP地址检测服务核心功能

- 实现配置文件加载和解析功能，支持服务器、MMDB数据库和日志配置
- 集成GeoLite2城市数据库查询，提供IP地理位置信息查询服务
- 添加私有IP地址检测逻辑，过滤本地网络地址段
- 构建HTTP路由处理器，返回JSON格式的IP位置信息
- 配置默认启动参数和错误处理机制
- 集成日志系统，记录请求处理过程和错误信息

internal/app/router.go

@@ -0,0 +1,52 @@
+package app
+
+import (
+	"net/http"
+
+	"checkIP/internal/mmdb"
+	"checkIP/internal/network"
+
+	"github.com/gin-gonic/gin"
+	"github.com/sirupsen/logrus"
+)
+
+func NewRouter(reader *mmdb.Reader) *gin.Engine {
+	router := gin.New()
+	router.Use(gin.Recovery())
+	router.Use(gin.LoggerWithWriter(logrus.StandardLogger().Out))
+
+	router.GET("/", func(c *gin.Context) {
+		ip := c.ClientIP()
+		if ip == "" {
+			c.String(http.StatusBadRequest, "Invalid IP")
+			return
+		}
+
+		ipInfo := network.GetIPInformation(ip)
+		fields := logrus.Fields{
+			"ip":         ipInfo.IP,
+			"is_private": ipInfo.IsPrivate,
+		}
+		if ipInfo.IsPrivate {
+			fields["private_cidr"] = ipInfo.PrivateCIDR
+		}
+		logrus.WithFields(fields).Info("ip check")
+
+		if ipInfo.IsPrivate {
+			c.String(http.StatusBadRequest, "Invalid IP")
+			return
+		}
+
+		ipLocation, err := reader.QueryIP(ipInfo.IP)
+		if err != nil {
+			logrus.WithError(err).Error("mmdb lookup failed")
+			c.Status(http.StatusInternalServerError)
+			return
+		}
+
+		logrus.WithField("ip_info", ipLocation).Info("mmdb lookup")
+		c.JSON(http.StatusOK, ipLocation)
+	})
+
+	return router
+}