今天做了一个简单的stmp邮件发送的客户端demo，可以支持带附件发送，希望将实现分享一下， 目前测试环境是公司的内部邮箱，
有gmail邮箱测试没有成功， 可能gmail邮箱需要ssl加密，后续再进行完善吧， 这个demo实现的非常简单的阻塞的发送发送邮件， 在后续的工作中需要
改成非阻塞的方式， 原理就是这样的。 你可以在网上stmp的原理，网上资料很多，在这里就不罗嗦了，本人水平有限， 如有问题，大家可以相互交流，共同
进步。
下面是源码：
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <errno.h>
#include <unistd.h>
#include <sys/time.h>
#include <netdb.h>
#define TEST_IMG ("test.jpg")
static char base64_table[64] =
{
'A', 'B', 'C', 'D', 'E', 'F', 'G',
'H', 'I', 'J', 'K', 'L', 'M', 'N',
'O', 'P', 'Q', 'R', 'S', 'T',
'U', 'V', 'W', 'X', 'Y', 'Z',
'a', 'b', 'c', 'd', 'e', 'f', 'g',
'h', 'i', 'j', 'k', 'l', 'm', 'n',
'o', 'p', 'q', 'r', 's', 't',
'u', 'v', 'w', 'x', 'y', 'z',
'0', '1', '2', '3', '4', '5', '6', '7', '8', '9',
'+', '/'
};
int base64_encode(unsigned char *buf, int nLen, char *pOutBuf, int nBufSize);
void sendemail(char *stmpServer, char *body);
int open_socket(struct sockaddr *addr);
int main()
{
FILE * fp = NULL;
char buf[128] = {0};
char outbuf[256] = {0};
char *body = NULL;
char email[] = "smtp.**.com";
#if 0
char body[] = "From: \"********\"<****@qq.com>\r\n"
"To: \"horst\"<>\r\n"
"Subject: Hello\r\n\r\n"
"this is a test!\n"
"good bye!"
"MIME-Version:1.0\r\n"
"Content-Type:multipart/mixed;boundary=\"---=_NextPart_000_0050_01C\"\r\n"
"Subject:=?gb2312?B?TU1NRdCt0unLtcP308q8/g==?=\r\n";
#endif
char bodyHead[] = "From: \"****\"<***@**.com>\r\n"
"To: \"**\"<**>\r\n"
"MIME-Version:1.0\r\n"
"Content-Type:multipart/mixed;boundary=\"---=_NextPart_000_0050_01C\"\r\n"
"Subject:test\r\n"
"\r\n"
"-----=_NextPart_000_0050_01C\r\n"
"Content-Type:text/plain;charset=\"gb2312\"\r\n"
"\r\n"
"hello \r\n"
"-----=_NextPart_000_0050_01C\r\n"
"\r\n\r\n"
"Content-Type:application/octet-stream;name=\"test.jpg\"\r\n"
"Content-Transfer-Encoding:base64\r\n"
"Content-Disposion:attachment;filename=\"test.jpg\""
"\r\n\r\n";
char bodyend[] = "\r\n-----=_NextPart_000_0050_01C\r\n";
body = malloc(8 * 1024 * 1024);
if(NULL == body)
{
perror("malloc(): ");
return -1;
}
memset(body, 0x0, 8*1024*1024);
sprintf(body, bodyHead);
fp = fopen(TEST_IMG, "rb");
if(fp == NULL)
{
perror("fopen(): ");
return -1;
}
memset(buf, 0x0, 128);
memset(outbuf, 0x0, 256);
int len = 0;
char *ptr = NULL;
ptr = body + strlen(body);
while((len = fread(buf, sizeof(char), 60, fp)) > 0)
{
base64_encode(buf, len, outbuf, sizeof(outbuf));
len = sprintf(outbuf, "%s\r\n", outbuf);
printf("len : %d\n", len);
sprintf(ptr, outbuf);
memset(buf, 0x0, 128);
memset(outbuf, 0x0, 256);
ptr += len;
}
sprintf(ptr, "\r\n\r\n");
ptr += strlen("\r\n\r\n");
sprintf(ptr, bodyend);
sendemail(email, body);
fclose(fp);
free(body);
return 0;
}
int base64_encode(unsigned char* pBase64, int nLen, char* pOutBuf, int nBufSize)
{
int i = 0;
int j = 0;
int nOutStrLen = 0;
/* nOutStrLen does not contain null terminator. */
nOutStrLen = nLen / 3 * 4 + (0 == (nLen % 3) ? 0 : 4);
if ( pOutBuf && nOutStrLen < nBufSize )
{
char cTmp = 0;
for ( i = 0, j = 0; i < nLen; i += 3, j += 4 )
{
/* the first character: from the first byte. */
pOutBuf[j] = base64_table[pBase64[i] >> 2];
/* the second character: from the first & second byte. */
cTmp = (char)((pBase64[i] & 0x3) << 4);
if ( i + 1 < nLen )
{
cTmp |= ((pBase64[i + 1] & 0xf0) >> 4);
}
pOutBuf[j+1] = base64_table[(int)cTmp];
/* the third character: from the second & third byte. */
cTmp = '=';
if ( i + 1 < nLen )
{
cTmp = (char)((pBase64[i + 1] & 0xf) << 2);
if ( i + 2 < nLen )
{
cTmp |= (pBase64[i + 2] >> 6);
}
cTmp = base64_table[(int)cTmp];
}
pOutBuf[j + 2] = cTmp;
/* the fourth character: from the third byte. */
cTmp = '=';
if ( i + 2 < nLen )
{
cTmp = base64_table[pBase64[i + 2] & 0x3f];
}
pOutBuf[j + 3] = cTmp;
}
pOutBuf[j] = '\0';
}
return nOutStrLen + 1;
}
/**
* @func sendemail
* @brief send email in blocking-mode
* @param smtpServer
* @param body
*/
void sendemail(char *smtpServer, char *body)
{
int sockfd = 0;
struct sockaddr_in their_addr = {0};
char buf[1500] = {0};
char rbuf[1500] = {0};
char login[128] = {0};
char pass[128] = {0};
struct hostent *host = NULL;
if((host = gethostbyname(smtpServer))==NULL)/*取得主机IP地址*/
{
fprintf(stderr,"Gethostname error, %s\n", strerror(errno));
exit(1);
}
memset(&their_addr, 0, sizeof(their_addr));
their_addr.sin_family = AF_INET;
their_addr.sin_port = htons(25);
their_addr.sin_addr = *((struct in_addr *)host->h_addr);
sockfd = open_socket((struct sockaddr *)&their_addr);
memset(rbuf, 0, 1500);
while(recv(sockfd, rbuf, 1500, 0) == 0)
{
printf("reconnect..\n");
close(sockfd);
sleep(2);
sockfd = open_socket((struct sockaddr *)&their_addr);
memset(rbuf, 0, 1500);
}
printf("%s\n", rbuf);
/* EHLO */
memset(buf, 0, 1500);
sprintf(buf, "EHLO abcdefg-PC\r\n");
send(sockfd, buf, strlen(buf), 0);
memset(rbuf, 0, 1500);
recv(sockfd, rbuf, 1500, 0);
printf("%s\n", rbuf);
/*AUTH LOGIN */
memset(buf, 0, 1500);
sprintf(buf, "AUTH LOGIN\r\n");
send(sockfd, buf, strlen(buf), 0);
printf("%s\n", buf);
memset(rbuf, 0, 1500);
recv(sockfd, rbuf, 1500, 0);
printf("%s\n", rbuf);
/* USER */
memset(buf, 0, 1500);
sprintf(buf, "********");
memset(login, 0, 128);
base64_encode(buf, strlen(buf), login, 128); /* base64 */
sprintf(buf, "%s\r\n", login);
send(sockfd, buf, strlen(buf), 0);
printf("%s\n", buf);
memset(rbuf, 0, 1500);
recv(sockfd, rbuf, 1500, 0);
printf("%s\n", rbuf);
/* PASSWORD */
memset(buf, 0, 1500);
sprintf(buf, "******");
memset(pass, 0, 128);
base64_encode(buf, strlen(buf), pass, 128);
memset(buf, 0, 1500);
sprintf(buf, "%s\r\n", pass);
send(sockfd, buf, strlen(buf), 0);
printf("%s, %d\n", buf, __LINE__);
memset(rbuf, 0, 1500);
recv(sockfd, rbuf, 1500, 0);
printf("%s, %d\n", rbuf, __LINE__);
/* MAIL FROM */
memset(buf, 0, 1500);
sprintf(buf, "MAIL FROM: <****@**.com>\r\n");
send(sockfd, buf, strlen(buf), 0);
memset(rbuf, 0, 1500);
recv(sockfd, rbuf, 1500, 0);
printf("%s\n", rbuf);
/* rcpt to 第一个收件人 */
sprintf(buf, "RCPT TO:<***@***.com>\r\n");
send(sockfd, buf, strlen(buf), 0);
memset(rbuf, 0, 1500);
recv(sockfd, rbuf, 1500, 0);
printf("%s\n", rbuf);
/* DATA email connext ready */
sprintf(buf, "DATA\r\n");
send(sockfd, buf, strlen(buf), 0);
memset(rbuf, 0, 1500);
recv(sockfd, rbuf, 1500, 0);
printf("%s\n", rbuf);
/* send email connext \r\n.\r\n end*/
sprintf(buf, "%s\r\n.\r\n", body);
send(sockfd, buf, strlen(buf), 0);
memset(rbuf, 0, 1500);
recv(sockfd, rbuf, 1500, 0);
printf("%s\n", rbuf);
/* QUIT */
sprintf(buf, "QUIT\r\n");
send(sockfd, buf, strlen(buf), 0);
memset(rbuf, 0, 1500);
recv(sockfd, rbuf, 1500, 0);
printf("%s\n", rbuf);
return ;
}
int open_socket(struct sockaddr *addr)
{
int sockfd = 0;
sockfd = socket(PF_INET, SOCK_STREAM, 0);
if(sockfd < 0)
{
fprintf(stderr, "Open sockfd(TCP ) error!\n");
exit(-1);
}
if(connect(sockfd, addr, sizeof(struct sockaddr)) < 0)
{
close(sockfd);
fprintf(stderr, "Connect sockfd(TCP ) error!\n");
exit(-1);
}
return sockfd;
}