socket 套接字

网络:交换机,路由器,网线

交换机:分配..

路由器:找寻网络线路

网络架构: 应用层 ---> 表示层 ---> 会话层 ---> 传输层 ---> 网络层 ---> 数据链路层 ----> 物理层

TCP/IP 商用: 应用层 ---> 传输层 ---> 网络层 ---> 物理+数据链路

socket 在传输层和应用层之间

TCP/IP 传输流程:

　　


一次连接三次握手:客服端访问服务器端,服务器端响应,服务器访问客户端,客户端响应

套接字之间的连接过程可以分为三个步骤：服务器监听，客户端请求，连接确认。

//服务器端

#import "AppDelegate.h"
#include <sys/socket.h>
#include <sys/types.h>
#include <arpa/inet.h>
#include <netinet/in.h>

@interface AppDelegate (){

//服务器标志

int server_flag;

//客户端标志

int client_flag;

//地址
struct sockaddr_in addr;

}

@end

@implementation AppDelegate

- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions {

// 错误
int error = -1;

#pragma mark --- 服务器端设置 ---

//创建服务器端 (IP类型,通信协议, )
server_flag = socket(AF_INET, SOCK_STREAM, 0);

//将服务器绑定到一个具体的计算机
//端口
addr.sin_port = htons(9006);
//计算机
addr.sin_addr.s_addr = INADDR_ANY;
//IPV4
addr.sin_family = AF_INET;

//server_flag 绑定

error = bind(server_flag, (struct sockaddr*)&addr, sizeof(addr));

//最大连接数
error = listen(server_flag, 100);

printf("服务器启动成功!\n");

//等待

while (YES) {
//等待接收
client_flag = accept(server_flag, NULL, NULL);

//保存接收数据
//字符数组
char buff[1024] = {0};

//接收数据长度
long length = 0;

length = recv(client_flag, buff, 1024, 0);

buff[length] = '\0';
printf("client asy : %s \n",buff);

//发送数据
send(client_flag, "hello world", 80, 0);

close(server_flag);

}

return YES;
}

//客户端

#import "AppDelegate.h"
#include <sys/socket.h>
#include <sys/types.h>
#include <arpa/inet.h>
#include <netinet/in.h>

@interface AppDelegate ()
{
int client_flag ;

struct sockaddr_in server;

}

@end

@implementation AppDelegate

- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions {

int error = -1;

client_flag = socket(AF_INET, SOCK_STREAM, 0);

server.sin_family = AF_INET;
server.sin_port = htons(9006);
server.sin_addr.s_addr = inet_addr("172.18.16.158");

error = connect(client_flag, (struct sockaddr*)&server, sizeof(server));
send(client_flag, "鲁二蛋", 1024, 0);

char buff[1024] = {0};

long length = 0;

length = recv(client_flag, buff, 1024, 0);

buff[length] = '\0';
printf("server say : %s\n",buff);

// close(client_flag);

return YES;
}