一、思维导图

二、给代码添加链表

        【server.c】

#include <stdio.h>
#include <sys/socket.h>
#include <sys/types.h>
#include <fcntl.h>
#include <arpa/inet.h>
#include <unistd.h>
#include <stdlib.h>
#include <string.h>typedef struct sockaddr_in addr_in_t;
typedef struct sockaddr addr_t;enum Type{TYPE_REGIST,TYPE_LOGIN
};typedef struct Pack{int size;enum Type type;char buf[2048];int count;
}pack_t;/*
typedef struct user_info{union Data{struct user_info* tail;char ui[20];}data;struct user_info* next;struct user_info* prev;
}UserInfo;UserInfo* create_node(){UserInfo* node = malloc(sizeof(UserInfo));node->next = NULL;node->prev = NULL;node->data.tail = node;return node;
}
*///从pack协议包中解析数据
void read_pack(pack_t* pack)
{char* buf = pack->buf;//记录buf已经读取的字节个数，方便定位到最靠前的未读取的位置int readed_size = 0;while(1){//将buf中最靠前未读取的2个字节，当作short读取，并赋值给data_sizeshort data_size = *(short*)(buf + readed_size);if(data_size == 0){printf("数据解析完毕\n");break;}//因为已经读取了2个字节，readed_size要自增2字节readed_size += 2;//准备一个大小为data_size+1的字符数组，用来接收数据char temp[data_size + 1];//初始化该数组memset(temp, 0, data_size+1);memcpy(temp, buf + readed_size, data_size);readed_size += data_size;printf("temp = %s\n", temp);}
}int main(int argc, const char* argv[])
{if(argc != 2){printf("请输入端口号！\n");return 1;}//将字符串转换成int类型portint port = atoi(argv[1]);//创建服务器套接字int server = socket(AF_INET, SOCK_STREAM, 0);//准备网络地址结构体： struct sockaddr_inaddr_in_t addr = {0};addr.sin_family = AF_INET;addr.sin_port = htons(port);addr.sin_addr.s_addr = inet_addr("0.0.0.0");//为套接字绑定ip和portif(bind(server, (addr_t*)&addr, sizeof(addr)) == -1){perror("bind()");return 1;}//监听listen(server, 10);//接收客户端的连接addr_in_t client_addr = {0};int client_addr_len = sizeof(client_addr);int client = accept(server, (addr_t*)&client_addr, &client_addr_len);if(client != -1){printf("=== 客户端连接 ===\n");}//读取客户端发来的消息while(1){int pack_size = 0;int res = read(client, &pack_size, 4);if(res == 0){printf("=== 客户端断开连接 === \n");return 0;}//当前的 pack_size = 4(pack.size大小) + 4(pack.type大小) + buf大小pack_t pack = {0};read(client, (char*)&pack+4, pack_size-4);pack.size = pack_size;//解析协议包的所有数据read_pack(&pack);}return 0;
}

        【client.c】

#include <stdio.h>
#include <sys/socket.h>
#include <sys/types.h>
#include <fcntl.h>
#include <arpa/inet.h>
#include <unistd.h>
#include <stdlib.h>
#include <string.h>typedef struct sockaddr_in addr_in_t;
typedef struct sockaddr addr_t;enum Type{TYPE_REGIST,TYPE_LOGIN
};typedef struct Pack{int size; //记录整个协议包实际大小(定长部分，占4个字节)enum Type type; //定长部分，占4个字节char buf[2048]; //变长部分，占count个字节int count; //记录指针偏移量，即buf使用了多少个字节
}pack_t;/*
typedef struct user_info{union Data{struct user_info* tail;char ui[20];}data;struct user_info* next;struct user_info* prev;
}UserInfo;UserInfo* create_node(){UserInfo* node = malloc(sizeof(UserInfo));node->next = NULL;node->prev = NULL;node->data.tail = node;return node;
}
*/void append(pack_t* pack, const char* data)
{char* buf = pack->buf;int len = strlen(data);//将buf的前2个字节当作short来存储数据len*(short*)(buf + pack->count) = len;pack->count += 2;memcpy(buf + pack->count, data, len);pack->count += len;pack->size = pack->count + 8;
}int main(int argc, const char* argv[])
{if(argc != 2){printf("请输入端口号！\n");return 1;}//将字符串转换成int类型portint port = atoi(argv[1]);int client = socket(AF_INET, SOCK_STREAM, 0);addr_in_t addr = {0};addr.sin_family = AF_INET;addr.sin_port = htons(port);addr.sin_addr.s_addr = inet_addr("192.168.126.155");if(connect(client, (addr_t*)&addr, sizeof(addr)) == -1){perror("connect()");return 1;}while(1){pack_t pack = {0};pack.type=TYPE_LOGIN;char name[20] = "";char pwd[20] = "";printf("请输入账号：");scanf("%20s", name);while(getchar() != 10);printf("请输入密码：");scanf("%20s", pwd);while(getchar() != 10);//前2个字节记录数据长度n，紧接着的n个字节记录数据本身//将name和pwd存入pack.buf中（即将name和pwd按照既定格式添加进协议包））append(&pack, name);append(&pack, pwd);//协议包总共占据 pack.count + 4 字节//pack.count 的长度，根据name和pwd的长度动态决定write(client, &pack, pack.size);}return 0;
}