TCP通信创建-粘包
什么是粘包？
粘包是指在网络中，由于 TCP 协议的特性，导致发送方发送的数据包被拆分成多个包，而接收方按照接收顺序组装成一个数据包。
从上⾯可以看出粘包主要分为两种情况:
多个完整的数据包粘在⼀起
⼀个数据包中包含另⼀个数据包的⼀部分
产⽣ tcp 粘包原因并⾮ tcp 协议本身引起的, 主要原因是 TCP 协议在底层是字节流，并不关
注, 应⽤层的消息边界, 可以是由发送⽅引起，也可以由接收⽅引起
解决粘包
⽅式⼀ : 使⽤定⻓数据包, 每次必须要读取固定⻓度的数据, 适⽤于数据⻓度是固定的
场景
⽅式⼆ : 使⽤数据⻓度 + 数据的⽅式，先接收数据⻓度，再根据⻓度接收数据, 这种⽅式适⽤于不定⻓数据场景
解决粘包使用 - 不定⻓数据
发送时，分两次发送，第⼀次发送数据⻓度，第⼆次发送数据
接收时，分两次接收，第⼀次接收数据⻓度，第⼆次接收数据
客户端代码实现
//todo tcp客户端,循环发送数据,接收回传数据,解决粘包问题,不定长的数据传输
#include <stdio.h>
#include <stdlib.h>
#include <sys/socket.h>
#include <sys/types.h>
#include <netinet/in.h>
#include <netinet/ip.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <string.h>
#include <unistd.h>
#define N 128
//初始化socket
int init_socket(char *ip,char *port){
int init_socket_fd= socket(AF_INET,SOCK_STREAM,0);
if (init_socket_fd==-1){
printf("init_socket err");
exit(EXIT_FAILURE);
}
struct sockaddr_in server_addr;
socklen_t len=sizeof(server_addr);
bzero(&server_addr,len);
server_addr.sin_family=AF_INET;
inet_aton(ip,&server_addr.sin_addr);
server_addr.sin_port= htons(atoi(port));
//连接
int ret= connect(init_socket_fd,(struct sockaddr*)&server_addr,len);
if (ret==-1){
printf("connect error,连接失败\n");
exit(EXIT_FAILURE);
}
return init_socket_fd;
}
//客户端接收数据
int Client_Receive_data(int socket_fd){
char receive_msg[N];
bzero(receive_msg,N);
int recv_len= recv(socket_fd, receive_msg,sizeof(receive_msg),0);
if (recv_len == -1) {
printf("recv error\n");
exit(EXIT_FAILURE);
}
receive_msg[recv_len] = '\0';
printf("收到客户端数据:[%s]\n",receive_msg);
}
//客户端发送数据
int Client_Send_data(int socket_fd){
char msg[N];
while (1){
bzero(&msg, sizeof (msg));
printf("请输入:\n");
fgets(msg, sizeof(msg),stdin);
msg[strlen(msg)-1]='\0';
printf("发送数据%s\n",msg);
//粘包解决
int old_msg_length= strlen(msg);
char *New_msg=(char *) malloc(old_msg_length+4);
memcpy(New_msg,&old_msg_length,4);
memcpy(New_msg+4,msg,old_msg_length);
int Send_data_len= send(socket_fd,New_msg, old_msg_length+4,0);
if (Send_data_len==-1){
printf("发送失败 send err\n");
exit(EXIT_FAILURE);
}
printf("发送了%d个字节\n",Send_data_len);
free(New_msg);
if (strncmp(msg, "exit", 4) == 0) {
printf("退出通信\n");
close(socket_fd);
break;
}
//接收
//Client_Receive_data(socket_fd);
}
return 0;
}
int main(){
//初始化连接
int socket_fd = init_socket("172.17.140.183","8081");
//发送数据
Client_Send_data(socket_fd);
return 0;
}
服务端代码实现
// todo TCP服务端程序 循环接收客户端数据,将数据回传,解决粘包问题,不定长的数据传输
#include <stdio.h>
#include <stdlib.h>
#include <sys/socket.h>
#include <sys/types.h>
#include <netinet/in.h>
#include <netinet/ip.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <string.h>
#include <unistd.h>
#define N 128
//初始化socket
int init_socket(char *ip,char *port){
int init_socket_fd= socket(AF_INET,SOCK_STREAM,0);
if (init_socket_fd==-1){
printf("init_socket err");
exit(EXIT_FAILURE);
}
struct sockaddr_in server_addr;
socklen_t len=sizeof(server_addr);
bzero(&server_addr,len);
server_addr.sin_family=AF_INET;
inet_aton(ip,&server_addr.sin_addr);
server_addr.sin_port= htons(atoi(port));
int bind_ret= bind(init_socket_fd,(struct sockaddr*)&server_addr,len);
if (bind_ret == -1) {
printf("bind error\n");
exit(EXIT_FAILURE);
}
int listen_ret= listen(init_socket_fd,10);
if (listen_ret == -1) {
printf("listen error\n");
exit(EXIT_FAILURE);
}
return init_socket_fd;
}
//客户端发送消息
int Server_Send_data(int clientFD,char* msg){
strcat(msg,"-回传");
int server_send_len=send(clientFD,msg,strlen(msg),0);
if (server_send_len == -1) {
printf("send error\n");
exit(EXIT_FAILURE);
}if (server_send_len == 0) {
printf("客户端关闭连接\n");
return -1;
}
printf("发送给客户端数据:[%s]\n",msg);
return 0;
}
//接收数据
int Server_Receive_data(int clientFD){
while (1){
//接收-使用新的文件描述符
//先接收四字节的长度
int msg_len=0;
int total_received=0;
int recv_len=recv(clientFD,&msg_len,4,0);
if (recv_len == -1) {
printf("recv error\n");
exit(EXIT_FAILURE);
}
if (recv_len == 0) {
printf("客户端关闭连接\n");
break;
}
while (1){
char recv_buf[N];
bzero(recv_buf,N);
recv_len = recv(clientFD, recv_buf+total_received, msg_len-total_received, 0);
if (recv_len == -1) {
printf("recv error\n");
exit(EXIT_FAILURE);
}
if (recv_len == 0) {
break;
}
if (strncmp(recv_buf, "exit", 4) == 0) {
printf("客户端退出通信\n");
close(clientFD);
return 0;
}
total_received+=recv_len;
printf("收到客户端消息:|%s|\n",recv_buf);
//Server_Send_data(clientFD, recv_buf);
}
}
return 0;
}
int main(){
int socket_fd = init_socket("172.17.140.183","8081");
struct sockaddr_in cli_addr;
socklen_t cli_len=sizeof(cli_addr);
//获取客户端连接
int clientFD= accept(socket_fd,(struct sockaddr*)&cli_addr,&cli_len);
if (clientFD == -1){
printf("accept error\n");
exit(EXIT_FAILURE);
}
printf("连接 ip:%s, port:%d\n",inet_ntoa(cli_addr.sin_addr),ntohs(cli_addr.sin_port));
//接收数据
Server_Receive_data(clientFD);
//关闭连接
close(clientFD);
}
