linux下用C編寫的基於smtp的郵件發送程序【轉】

smtp協議原理：http://blog.csdn.net/woshinia/article/details/8994833

 

個人webf服務器是動態ip，所以須要檢測服務器ip的變化而後更新域名的ip，打算檢測到ip變化後自動發送郵件告知本身，因而上網搜了下編程發送郵件的方法，大部分是基於vc的，我找了個例子修改爲了linux下的程序。這個程序是基於smtp協議的，smtp是基於tcp的，有興趣的能夠先本身看看smtp協議，這樣看程序會更容易理解。

 

這個程序目前126的郵箱經測試成功發送，新浪的雖然顯示發送成功可是總也收不到，有空再慢慢實驗吧，其餘郵箱還未測試。

程序以下：

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <errno.h>
#include <unistd.h>
#include <netinet/in.h>
#include <limits.h>
#include <netdb.h>
#include <arpa/inet.h>
#include <ctype.h>

// Function prototype
void StreamClient(char *szServer, short nPort, char *szMessage);
// Helper macro for displaying errors

////////////////////////////////////////////////////////////

int main(int argc, char **argv)
{
char hostname[255];
int nRet;
short nPort;
nPort =25;
StreamClient("smtp.126.com", nPort, "AUTH LOGIN\r\n");
return 0;
}

////////////////////////////////////////////////////////////

void StreamClient(char *szServer, short nPort, char *szMessage)
{

int sockfd;
char buffer[1024];
struct sockaddr_in server_addr;
struct hostent *host;

if((host=gethostbyname(szServer))==NULL)/*取得主機IP地址*/
{
fprintf(stderr,"Gethostname error, %s\n", strerror(errno));
exit(1);
}

if((sockfd=socket(AF_INET,SOCK_STREAM,0))==-1)/*創建SOCKET鏈接*/
{
fprintf(stderr,"Socket Error:%s\a\n",strerror(errno));
exit(1);
}

/* 客戶程序填充服務端的資料 */
bzero(&server_addr,sizeof(server_addr));
server_addr.sin_family=AF_INET;
server_addr.sin_port=htons(nPort);
server_addr.sin_addr=*((struct in_addr *)host->h_addr);

/* 客戶程序發起鏈接請求 */
if(connect(sockfd,(struct sockaddr *)(&server_addr),sizeof(struct sockaddr))==-1)/*鏈接網站*/
{
fprintf(stderr,"Connect Error:%s\a\n",strerror(errno));
exit(1);
}

printf("\nStream Client connecting to server: %s on port: %d",szServer, nPort);

char szBuf[1024];
memset(szBuf,0,1024);
int nRet;
// strcpy(szBuf, "From the Client");
char buf[350]="0";
char server[250];
gethostname(server,250);
strcpy(buf, "HELO ");

strcat(buf, szServer);
strcat(buf, " \r\n");
printf("%s:::%d",buf,strlen(buf));

//
// Wait for a reply
//
nRet = recv(sockfd,szBuf,sizeof(szBuf)+1,0);  printf("\nData received OVER DATA: %s", szBuf);

nRet = send(sockfd, buf, strlen(buf), 0);printf("\nsend %s",buf);
nRet = recv(sockfd, szBuf, sizeof(szBuf), 0); printf("\nData received2: %s", szBuf);

//發送準備登錄信息
nRet = send(sockfd, "AUTH LOGIN\r\n", strlen("AUTH LOGIN\r\n"), 0);
nRet = recv(sockfd, szBuf, sizeof(szBuf), 0); printf("\nData received LOGIN: %s", szBuf);

//發送用戶名和密碼,這裏的用戶名和密碼必須用base64進行轉碼,發送轉碼之後的字符串，對於126郵箱來講用戶名是@前面的字符串
nRet = send(sockfd,"轉碼後的用戶名\r\n", strlen("轉碼後的用戶名\r\n"),0);printf("\nData Send USERNAME");
nRet = recv(sockfd, szBuf, sizeof(szBuf),0);printf("\nData received USERNAME: %s", szBuf);printf("\nData Send PASS");

//發送用戶密碼
nRet = send(sockfd,"轉碼後的密碼\r\n", strlen("轉碼後的密碼\r\n"), 0);
//printf("\nData Send PASS");
nRet = recv(sockfd, szBuf, sizeof(szBuf),0); printf("\nData received USERPASSWORD: %s", szBuf);

//發送[發送郵件]的信箱(改爲你的郵箱!），該郵箱要與用戶名一致，不然發送不成功
send(sockfd,"MAIL FROM: <server_ip_alert@126.com>\r\n",strlen("MAIL FROM: <server_ip_alert@126.com>\r\n"),0);printf("\nsend MAIL FROM\n");
nRet = recv(sockfd, szBuf, sizeof(szBuf), 0);printf("\nData received MAILFROM: %s", szBuf);

//發送[接收郵件]的郵箱
nRet= send(sockfd,"RCPT TO: <tootoogo@hotmail.com>\r\n",strlen("RCPT TO: <tootoogo@hotmail.com>\r\n"),0);printf("\nsend RCPT TO\r\n");
nRet = recv(sockfd, szBuf, sizeof(szBuf), 0);   printf("\nData received TO MAIL: %s", szBuf);
/*
nRet= send(sockfd,"RCPT TO: <server_ip_alert@hotmail.com>\r\n",strlen("RCPT TO: <server_ip_alert@hotmail.com>\r\n"),0);printf("\nsend RCPT TO\r\n");
nRet = recv(sockfd, szBuf, sizeof(szBuf), 0);   printf("\nData received TO MAIL: %s", szBuf);
*/
char MailData[] ="From: \"server_ip_alert@sina.com\"<server_ip_alert@sina.com>\r\nTo: tootoogo@hotmail.com\r\nSubject: IP Address\r\n\r\n"; //主題能夠改爲別的

//各訴郵件服務器，準備發送郵件內容

send(sockfd,"DATA\r\n", strlen("DATA\r\n"),0);printf("\nsend DATA\n");
//  nRet = recv(sockfd, szBuf, sizeof(szBuf)+1, 0); printf("\nData receivedSEND DATA: %s", szBuf);
//發送郵件標題
send(sockfd,MailData, strlen(MailData),0);
//發送郵件內容
send(sockfd,"test!!!!\r\n", strlen("abcdefg\r\n"),0);//我隨便寫了幾個字符進行測試
//發送郵件結束
send(sockfd,"\r\n.\r\n", strlen("\r\n.\r\n"),0);
//接收郵件服務器返回信息
nRet = recv(sockfd,szBuf,sizeof(szBuf),0);  printf("\nData received OVER DATA: %s", szBuf);
send(sockfd,"QUIT\r\n", strlen("QUIT\r\n"),0);
nRet = recv(sockfd,szBuf,sizeof(szBuf),0);  printf("\nData received QUIT: %s", szBuf);

//
// Display the received data
//
//printf("\nData received3: %s", szBuf);

close(sockfd);
return;
}

其餘方法：（基於libesmtp庫）

一、安裝庫libesmtp-devel

yum install libesmtp-devel
或
apt-get install libesmtp-devel

若是無法用命令安裝，就上http://www.stafford.uklinux.net/libesmtp/本身下載包安裝。

二、不認證便可發信息

#define _XOPEN_SOURCE
#include <stdio.h>
#include <stdlib.h>
#include <ctype.h>
#include <unistd.h>
#include <getopt.h>
#include <string.h>
#include <fcntl.h>
#include <signal.h>
#include <errno.h>
#include <stdarg.h>
#include <libesmtp.h>

int main() {
    smtp_session_t session;
    smtp_message_t message;
    struct sigaction sa;
    const smtp_status_t *status;
    char buf[128];
    FILE *fp;
    /* This program sends only one message at a time. Create an SMTP
       session and add a message to it. */
    if( (session = smtp_create_session ()) == NULL){
        fprintf (stderr, "smtp_create_session problem %s\n",
                smtp_strerror (smtp_errno (), buf, sizeof buf));
        return 1;
    }
    if((message = smtp_add_message (session)) == NULL){
        fprintf (stderr, "smtp_add_message problem %s\n",
                smtp_strerror (smtp_errno (), buf, sizeof buf));
        return 1;
    }
    /* NB. libESMTP sets timeouts as it progresses through the protocol.
       In addition the remote server might close its socket on a timeout.
       Consequently libESMTP may sometimes try to write to a socket with
       no reader. Ignore SIGPIPE, then the program doesn't get killed
       if/when this happens. */
    sa.sa_handler = SIG_IGN;
    sigemptyset (&sa.sa_mask);
    sa.sa_flags = 0;
    sigaction (SIGPIPE, &sa, NULL); 
    /* Set the host running the SMTP server. LibESMTP has a default port
       number of 587, however this is not widely deployed so the port
       is specified as 25 along with the default MTA host. */
    smtp_set_server (session, "127.0.0.1:25");
    /* Set the reverse path for the mail envelope. (NULL is ok)
     */
    smtp_set_reverse_path (message, "test@test.com");
    /* RFC 2822 doesn't require recipient headers but a To: header would
     * be nice to have if not present. */
    smtp_set_header (message, "To", NULL, NULL);
    smtp_set_header (message, "Subject", " test mail");
    smtp_set_header_option (message, "Subject", Hdr_OVERRIDE, 1);
    fprintf(stderr,"%s\n","smtp_set_server.");
    if ((fp = fopen ("test-mail.eml", "r")) == NULL) {
        fprintf (stderr, "can't open mail file: %s\n", strerror (errno));
        return (1);
    }
    smtp_set_message_fp (message, fp);
    smtp_add_recipient (message,"yourQQ@qq.com");
    /* Initiate a connection to the SMTP server and transfer the
       message. */
    if (!smtp_start_session (session)){
        fprintf (stderr, "SMTP server problem %s\n",
                smtp_strerror (smtp_errno (), buf, sizeof buf));
    }
    else{
        /* Report on the success or otherwise of the mail transfer.
        */
        status = smtp_message_transfer_status (message);
        printf ("%d %s", status->code,
                (status->text != NULL) ? status->text : "\n");
    }
    /* Free resources consumed by the program.
    */
    smtp_destroy_session (session);
    if(fp != NULL){
        fclose(fp);
    }

    return 0;
}

三、把上面的代碼寫入sendmail.c，並把裏面的"yourQQ@qq.com"替換成你本身的QQ郵箱地址或者其它郵箱地址，而後用下面命令編譯

gcc -std=c99 -Wall `libesmtp-config --cflags`   -o sendmail sendmail.c -lesmtp

四、同目錄下新建test-mail.eml文件，裏面內容隨便本身填。

五、運行

./sendmail