/**
 * gcc server.c -lcrypto -o server
 */

#include <stdlib.h>
#include <unistd.h>
#include <stdio.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <string.h>
#include <errno.h>
#include <openssl/md5.h>
#include <string
 
.h>
#include <stdio.h>

void gen_md5(char *data, char *md5)
{
    unsigned char md[16] = {0};
    int i = 0;
    char tmp[3] = {'\0'};

    MD5((const unsigned char *)data, strlen((char *)data), md);

    for (i = 0; i < 16; i++)
    {
        sprintf(tmp, "%02X", md[i]);
        strcat(md5, tmp);
    }
}

 
void print_package(char *package)
{
    char package_md5[33] = {0};
    char package_data[100] = {0};
    char cal_md5[33] = {'\0'};
    memcpy(package_md5, &package[1], 32);
    memcpy(package_data, &package[33], strlen(package) - 33);
    printf("資料包的長度 【%d】 \n", package[0]);
    printf("資料包md5    【%s】 \n
 
", package_md5);
    printf("資料包字串 【%s】 \n", package_data);

    gen_md5(package_data, cal_md5);
    if (strcmp(package_md5, cal_md5) == 0)
    {
        puts("md5校驗通過");
    }
    else
    {
        printf("md5校驗未通過package_md5 %s和cal_md5 %s不匹配", package_md5, cal_md5);
    }
}

int main()
{
    int listenfd, connfd;
    struct sockaddr_in servaddr;
    char package[129];

    bzero(&servaddr, sizeof(servaddr));
    servaddr.sin_family = AF_INET;
    servaddr.sin_port = htons(5000);
    servaddr.sin_addr.s_addr = htonl(INADDR_ANY);

    listenfd = socket(AF_INET, SOCK_STREAM, 0);
    bind(listenfd, (struct sockaddr *)&servaddr, sizeof(servaddr));

    listen(listenfd, 5);

    for (;;)
    {
        connfd = accept(listenfd, (struct sockaddr *)NULL, NULL);
        puts("***********************************");
        memset(package, 0, sizeof(package));
        recv(connfd, package, 129, 0);
        puts("接收資料ok");
        print_package(package);
        write(connfd, "ok", 3);
        close(connfd);
        puts("關閉連線");
        puts("***********************************");
    }
}

/**
 * gcc client.c -lcrypto -o client
 */

#include <stdlib.h>
#include <unistd.h>
#include <stdio.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <string.h>
#include <errno.h>
#include <openssl/md5.h>
#include <string.h>
#include <stdio.h>


void gen_md5(char *data, char *md5)
{
    unsigned char md[16] = {0};
    int i = 0;
    char tmp[3] = {'\0'};

    MD5((const unsigned char *)data, strlen((char *)data), md);

    for (i = 0; i < 16; i++)
    {
        sprintf(tmp, "%02X", md[i]);
        strcat(md5, tmp);
    }
}

void build_package(char *data, char *package)
{
    char md5[33] = {'\0'};
    int length;
    gen_md5(data, md5);

    length = strlen((char *)md5) + strlen((char *)data);
    memset(package, '\0', sizeof(package));
    package[0] = length;
    strcpy(&package[1], (char *)md5);
    strcpy(&package[33], (char *)data);
    // strcpy(&package[33], "helle world");
}

int main(void)
{
    int sockfd, n;
    struct sockaddr_in servaddr;
    char server_reply[1024]={0};
    bzero(&servaddr, sizeof(servaddr));
    servaddr.sin_family = AF_INET;
    servaddr.sin_port = htons(5000);
    inet_pton(AF_INET, "127.0.0.1", &servaddr.sin_addr);

    sockfd = socket(AF_INET, SOCK_STREAM, 0);

    connect(sockfd, (struct sockaddr *)&servaddr, sizeof(servaddr));
    char data[] = "hello world";
    char package[129] = {0};
    
    build_package(data, package);
    send(sockfd, package, strlen(package), 0);
    puts("傳送資料ok");
    
    recv(sockfd, server_reply, 1024, 0);
    puts("接收資料ok");
    puts(server_reply);
    close(sockfd);
    return 0;
}