ubuntu openssl 连接gmial smtp服务

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#ubuntu #ssl #c语言 #openssl

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本文介绍如何利用OpenSSL库实现SSL加密，并通过SMTP协议发送带认证的加密邮件。具体步骤包括安装OpenSSL开发库、编写C语言程序来处理邮件信息输入、域名解析、服务器连接及SMTP交互等。

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引用我的代码片

OpenSSL 是一个安全套接字层密码库，囊括主要的密码算法、常用的密钥和证书封装管理功能及SSL协议，并提供丰富的应用程序供测试或其它目的使用

1.安装开发库

sudo apt-get install libssl-dev

2.创建c语言文件

我命名为 test.c

3.包含ssl头文件

/*openssl*/

#include <openssl/ssl.h>
#include <openssl/bio.h>

4.包含socket头文件

/*socket*/

#include <sys/socket.h>
#include <netinet/in.h>
#include <netdb.h>
#include <arpa/inet.h>

5.添加标准库

#include<stdio.h>
#include<stdlib.h>
#include<string.h>

6.添加一个结构体保存基本信息

struct email{
    char *username;      //登陆用户名
    char *password;      //登陆密码
    char *from;          //邮箱来自
    char *send;          //邮箱发送
    char *title;         //邮件标题
    char *body;          //邮件内容
}mail;



7.新建一个函数 GetEmailInfo() 用于获取基本信息


int GetEmailInfo() {
	mail.username = (char *)malloc(64 * (sizeof(char)));
	mail.password = (char *)malloc(64 * (sizeof(char)));
	mail.title = (char *)malloc(64 * (sizeof(char)));
	mail.body = (char *)malloc(64 * (sizeof(char)));
	mail.send = (char *)malloc(64 * (sizeof(char)));
	mail.from = (char *)malloc(64 * (sizeof(char)));


	printf("请输入你的邮箱地址:"); 
	scanf("%s",mail.username);
	printf("请输入你的邮箱密码:");
	scanf("%s", mail.password);
	printf("请输入收件人信息:");
	scanf("%s", mail.send);
	printf("请输入邮件的标题:");
	scanf("%s",mail.title);
	printf("请输入邮件内容:");
	scanf("%s",mail.body);
	strcpy(mail.from, mail.username);

	return 0;
}

8. 新建函数 char *GetIpAddress(const char *domain) 用于把域名转换为ip

char *GetIpAddress(const char *domain){
    const char *ip = NULL;
    struct in_addr *host_name;
    struct hostent *list =gethostbyname(domain);
    int x=0;
    for(x;list->h_addr_list[x]!=0;x++){
        host_name= list->h_addr_list[x];
        ip = inet_ntoa(*host_name);
    }
    return ip;
}

9.新建函数 ConnectServer(const char * ServerAddr)用于连接服务器

int connectToServer(const char *ServerAdd){

    int socket_fd = socket(AF_INET,SOCK_STREAM,IPPROTO_IP);
    struct sockaddr_in client;
    memset(&client,0,sizeof(client));
    client.sin_family = AF_INET;
    client.sin_port =htons(465);

    if(inet_pton(AF_INET,GetIpAddress(ServerAdd),&client.sin_addr)==1){
        connect(socket_fd,&client,sizeof(client));
    }
    return socket_fd;

}

10.base64

const char * base64char = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";

char * mybase64_encode( const unsigned char * bindata, char * base64, int binlength )
{
    int i, j;
    unsigned char current;

    for ( i = 0, j = 0 ; i < binlength ; i += 3 )
    {
        current = (bindata[i] >> 2) ;
        current &= (unsigned char)0x3F;
        base64[j++] = base64char[(int)current];

        current = ( (unsigned char)(bindata[i] << 4 ) ) & ( (unsigned char)0x30 ) ;
        if ( i + 1 >= binlength )
        {
            base64[j++] = base64char[(int)current];
            base64[j++] = '=';
            base64[j++] = '=';
            break;
        }
        current |= ( (unsigned char)(bindata[i+1] >> 4) ) & ( (unsigned char) 0x0F );
        base64[j++] = base64char[(int)current];

        current = ( (unsigned char)(bindata[i+1] << 2) ) & ( (unsigned char)0x3C ) ;
        if ( i + 2 >= binlength )
        {
            base64[j++] = base64char[(int)current];
            base64[j++] = '=';
            break;
        }
        current |= ( (unsigned char)(bindata[i+2] >> 6) ) & ( (unsigned char) 0x03 );
        base64[j++] = base64char[(int)current];

        current = ( (unsigned char)bindata[i+2] ) & ( (unsigned char)0x3F ) ;
        base64[j++] = base64char[(int)current];
    }
    base64[j] = '\0';
    return base64;
}

11.主函数

int main(void){



    GetEmailInfo();


    BIO  *obj_bio =NULL;
    BIO  *obj_out =NULL;
    const SSL_METHOD *method =NULL;
    SSL_CTX  *ctx=NULL;
    SSL *ssl;

    int connect_fd = 0;
    int ret,i;
    ret=i=0;
    OpenSSL_add_all_algorithms();
    ERR_load_BIO_strings();
    ERR_load_CRYPTO_strings();
    SSL_load_error_strings();

    obj_bio = BIO_new(BIO_s_file());
    obj_out = BIO_new_fp(stdout,BIO_NOCLOSE);

    if(SSL_library_init()<=0){
        BIO_printf(obj_out,"ssl iniliatile fail");

    }
    else{
        method = SSLv23_client_method();
        if((ctx=SSL_CTX_new(method))==NULL){
            BIO_printf(obj_out,"open ssl  fail");
        }

        else{
            SSL_CTX_set_options(ctx,SSL_OP_NO_SSLv2);
            ssl=SSL_new(ctx);
            connect_fd = connectToServer("smtp.gmail.com");

            if(connect_fd!=0){

                BIO_printf(obj_out,"success connect\n");

                SSL_set_fd(ssl,connect_fd);


                if(SSL_connect(ssl) !=0){


                     char *rn ="\r\n";
                     char buf[4096];
                     char rbuf[4768];
                     memset(buf,0,sizeof(buf));
                     memset(rbuf,0,sizeof(rbuf));


                     SSL_read(ssl,rbuf,sizeof(rbuf));
                     BIO_printf(obj_out,rbuf);
                     memset(rbuf,0,sizeof(rbuf));


                     strcpy(&buf,"HELO SERVER");
                     strcat(buf,rn);
                     SSL_write(ssl,buf,strlen(buf));
                     BIO_printf(obj_out,buf);
                     memset(&buf,0,sizeof(buf));


                     SSL_read(ssl,rbuf,sizeof(rbuf));
                     BIO_printf(obj_out,rbuf);
                     memset(rbuf,0,sizeof(rbuf));



                     strcpy(&buf,"AUTH LOGIN");
                     strcat(buf,rn);
                     SSL_write(ssl,buf,strlen(buf));
                     BIO_printf(obj_out,buf);
                     memset(&buf,0,sizeof(buf));


                     SSL_read(ssl,rbuf,sizeof(rbuf));
                     BIO_printf(obj_out,rbuf);
                     memset(rbuf,0,sizeof(rbuf));


                     mybase64_encode(mail.username,&buf,strlen(mail.username));
                     strcat(buf,rn);
                     SSL_write(ssl,buf,strlen(buf));
                     BIO_printf(obj_out,buf);
                     memset(buf,0,sizeof(buf));



                     SSL_read(ssl,rbuf,sizeof(rbuf));
                     BIO_printf(obj_out,rbuf);
                     memset(rbuf,0,sizeof(rbuf));;



                     mybase64_encode(mail.password,&buf,strlen(mail.password));
                     strcat(buf,rn);
                     SSL_write(ssl,buf,strlen(buf));
                     BIO_printf(obj_out,buf);
                     memset(buf,0,sizeof(buf));


                     SSL_read(ssl,rbuf,sizeof(rbuf));
                     BIO_printf(obj_out,rbuf);
                     memset(rbuf,0,sizeof(rbuf));

                     strcpy(buf,"mail from:<");
                     strcat(buf,mail.from);
                     strcat(buf,">");
                     strcat(buf,rn);
                     SSL_write(ssl,buf,strlen(buf));
                     BIO_printf(obj_out,buf);
                     memset(buf,0,sizeof(buf));


                     SSL_read(ssl,rbuf,sizeof(rbuf));
                     BIO_printf(obj_out,rbuf);
                     memset(rbuf,0,sizeof(rbuf));

                     strcpy(buf,"rcpt to:<");
                     strcat(buf,mail.send);
                     strcat(buf,">");
                     strcat(buf,rn);
                     SSL_write(ssl,buf,strlen(buf));
                     BIO_printf(obj_out,buf);
                     memset(buf,0,sizeof(buf));

                     SSL_read(ssl,rbuf,sizeof(rbuf));
                     BIO_printf(obj_out,rbuf);
                     memset(rbuf,0,sizeof(rbuf));

                     strcpy(buf,"data");
                     strcat(buf,rn);
                     SSL_write(ssl,buf,strlen(buf));
                     BIO_printf(obj_out,buf);
                     memset(buf,0,sizeof(buf));

                     SSL_read(ssl,rbuf,sizeof(rbuf));
                     BIO_printf(obj_out,rbuf);
                     memset(rbuf,0,sizeof(rbuf));

                     strcpy(buf,"subject:");
                     strcat(buf,mail.title);
                     strcat(buf,rn);
                     SSL_write(ssl,buf,strlen(buf));
                     BIO_printf(obj_out,buf);
                     memset(buf,0,sizeof(buf));

                     strcat(buf,mail.body);
                     strcat(buf,rn);
                     strcat(buf,".");
                     strcat(buf,rn);
                     SSL_write(ssl,buf,strlen(buf));
                     BIO_printf(obj_out,buf);
                     memset(buf,0,sizeof(buf));

                     SSL_read(ssl,rbuf,sizeof(rbuf));
                     BIO_printf(obj_out,rbuf);
                     memset(rbuf,0,sizeof(rbuf));

                     strcpy(buf,"quit");
                     strcat(buf,rn);
                     SSL_write(ssl,buf,strlen(buf));
                     BIO_printf(obj_out,buf);
                     memset(buf,0,sizeof(buf));


                     SSL_read(ssl,rbuf,sizeof(rbuf));
                     BIO_printf(obj_out,rbuf);
                     memset(rbuf,0,sizeof(rbuf));

                 }
        }
    }
}
    return 0;
}