電子郵件傳送的原理以及簡易實現
阿新 • • 發佈：2019-01-08
在程式碼開始之前，我們先手工模擬一遍傳送電子郵件的過程，那麼接下來的程式碼你就容易懂多了！
下面以163郵箱為例！
先鍵入telnet命令，然後連線到網易的smtp伺服器,使用25號埠.
接著看下圖:
<<<<<<
從現在開始，我們可以模擬傳送信件的過程了!
傳送命令：EHLO hello (hello可以任意替換)
然後我們請求登陸！
傳送命令: AUTH LOGIN
然後傳送自己賬戶的使用者名稱的base64編碼(不要@XXX.com)過去!我用的一個測試郵箱 [email protected],it_is_just_a_test的base64編碼是aXRfaXNfanVzdF9hX3Rlc3Q=
然後將自己的密碼的base64編碼發過去！我的密碼的base64編碼是MTk5MzA3MTRseWg=
伺服器告訴你認證成功了！我們現在就可以傳送郵件了!
先發送郵件說明:MAIL FROM: <[email protected]>
然後傳送目的郵箱說明:RCPT TO: <[email protected]>
然後請求傳送郵件:DATA
然後傳送郵件頭和郵件體，傳送資料：
From: [email protected]
Subject: 測試一下
MIME-Version: 1.0
這是一封測試郵件!!! .
(在正文輸入結束時回車輸入一個 . （英文輸入法下的句號）然後再回車，表示正文部分的結束。這時將顯示郵件成功傳送的資訊。)<CR><LF>表示的是回車
當信件傳送完成了之後，我們可以利用quit命令關閉與伺服器的連線！
基本原理就是這樣了：然後我們來看程式碼吧！(利用程式傳送的時候無非就是把回車換成"\r\n"!)
#include <iostream>
#include <WinSock2.h>
#include <windows.h>
#include <string.h>
using namespace std;
#pragma comment(lib, "ws2_32.lib") /*連結ws2_32.lib動態連結庫*/
const int MAXSIZE = 1024;
int srvPort = 25;
char srvDomain[256] = "smtp.163.com";
char userName[256] = "[email protected]"; //自己的郵箱名稱
char password[256] = "19930714lyh"; //自己郵箱的密碼
char targetEmail[256] = "[email protected]"; //要傳送的郵件地址
char emailTitle[256] = "你好！我是李樹花開！"; //郵件主題
char content[256] = "這是一封測試郵件！很高興我的第一個郵件客戶端製作成功了！";//郵件正文
SOCKET CreateConn(char* pWebsite,int port)
{
//為建立socket物件做準備，初始化環境
SOCKET sockClient = socket(AF_INET,SOCK_STREAM,0); //建立socket物件
SOCKADDR_IN addrSrv;
HOSTENT* pHostent;
pHostent = gethostbyname(pWebsite); //得到有關於域名的資訊
addrSrv.sin_addr.S_un.S_addr = *((DWORD *)pHostent->h_addr_list[0]); //得到smtp伺服器的網路位元組序的ip地址
addrSrv.sin_family=AF_INET;
addrSrv.sin_port=htons(port);
int tf = connect(sockClient,(SOCKADDR*)&addrSrv,sizeof(SOCKADDR)); //向伺服器傳送請求
if(tf!=0)
{
return 0;
//printf("連結失敗\n");
}
return sockClient;
}
//int DoWhat是否接受資料
void SendAndRecvMsg(
SOCKET sockClient, //客戶端的套接字
char* pMessage, //要傳送的訊息
int Messagelen, //訊息的長度
int DoWhat, //造作的型別
char* recvBuf, //接收的緩衝區
int recvBufLen //緩衝區長度
)
{
char lpMessage[256] = {0};
memcpy(lpMessage, pMessage, Messagelen);
printf("\n\n%s \n", lpMessage);
if (DoWhat == 0)
{
send(sockClient, lpMessage, Messagelen, 0);
memset(recvBuf , 0, recvBufLen);
DWORD num = recv(sockClient, recvBuf, recvBufLen, 0); //接收資料
printf("%s \n", recvBuf);
int i = 0;
while(i != num)
{
printf("%02X ", recvBuf[i++]);
if((i)%16 == 0)
{
printf("\n");
}
}
printf("\n");
}
else if (DoWhat == 1)
{
send(sockClient, lpMessage, Messagelen, 0);
}
else if (DoWhat == 2) //僅僅是接收資料
{
memset(recvBuf, 0, recvBufLen);
DWORD num=recv(sockClient,recvBuf,recvBufLen,0); //接收資料
cout << recvBuf << endl;
int i = 0;
while(i < num)
{
printf("%02X ", (byte)recvBuf[i++]);
if((i)%16 == 0)
{
printf("\n");
}
}
printf("\n");
}
}
int GetStrLen(char* pString) //得到字串的長度
{
int i = 0;
while(pString[i++] != 0);
return i-1;
}
void StringToBase64(const char *src,char *dst)
{/*將字串變為base64編碼*/
int i = 0;
char *p = dst;
int d= strlen(src) - 3;
static const char Base64[] =
"ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
//for(i=0;i<strlen(src)-3;i+=3) ;if (strlen(src)-3)<0 there is a buf
for(i=0;i<=d;i+=3)
{
*p++ = Base64[((*(src + i)) >> 2) & 0x3f];
*p++ = Base64[(((*(src + i)) & 0x3) << 4) + ((*(src + i + 1)) >> 4)];
*p++ = Base64[((*(src + i + 1) & 0xf) << 2) + ((*(src + i + 2)) >> 6)];
*p++ = Base64[(*(src + i + 2)) & 0x3f];
}
if((strlen(src) - i) == 1)
{
*p++ = Base64[((*(src + i)) >> 2) & 0x3f];
*p++ = Base64[((*(src + i)) & 0x3) << 4];
*p++ = '=';
*p++ = '=';
}
if((strlen(src) - i) == 2)
{
*p++ = Base64[((*(src + i)) >> 2) & 0x3f];
*p++ = Base64[(((*(src + i)) & 0x3) << 4) + ((*(src + i + 1)) >> 4)];
*p++ = Base64[((*(src + i + 1) & 0xf) << 2)];
*p++ = '=';
}
*p = '\0';
}
bool FormatEmail(char* pFrom, char* pTo, char* pSubject, char* pMessage, char* Email)
{/*格式化要傳送的內容*/
lstrcat(Email, "From: ");
lstrcat(Email, pFrom);
lstrcat(Email, "\r\n");
lstrcat(Email, "To: ");
lstrcat(Email, pTo);
lstrcat(Email, "\r\n");
lstrcat(Email, "Subject: ");
lstrcat(Email, pSubject);
lstrcat(Email, "\r\n");
lstrcat(Email, "MIME-Version: 1.0");
lstrcat(Email, "\r\n");
lstrcat(Email, "\r\n");
lstrcat(Email, pMessage);
lstrcat(Email, "\r\n.\r\n");
return TRUE;
}
void main()
{
WORD wVersionRequested;
WSADATA wsaData;
int err;
wVersionRequested = MAKEWORD(2, 1);
err = WSAStartup(wVersionRequested, &wsaData);
SOCKET sockClient = CreateConn(srvDomain, srvPort); //網易smtp郵箱，25號埠
char buff[MAXSIZE];
memset(buff, 0, sizeof(char) * MAXSIZE); //清零
SendAndRecvMsg(sockClient, 0, 0, 2, buff, MAXSIZE); //接收資料
char UserNameToSendEmail[256] = {0};
sprintf(UserNameToSendEmail, "EHLO %s", "[email protected]");
lstrcat(UserNameToSendEmail, "\r\n\0");
SendAndRecvMsg(sockClient, UserNameToSendEmail, GetStrLen(UserNameToSendEmail), 0, buff, MAXSIZE); //既接收也傳送
SendAndRecvMsg(sockClient, "AUTH LOGIN\r\n", strlen("AUTH LOGIN\r\n"), 0, buff, MAXSIZE); //請求登陸
char pUerName[256] = {0};
//strstr函式搜尋一個字串在另一個字串中的第一次出現，並返回第一次出現位置的指標
DWORD p = strstr(userName,"@") - userName;
memcpy(pUerName, userName, p); //得到使用者名稱,如從"[email protected]"得到"13203200199"
char base[256];
StringToBase64(pUerName, base); //得到使用者名稱的base64編碼
char str[MAXSIZE];
memset(str, 0, MAXSIZE);
sprintf(str, "%s\r\n", base/*"MTMyMDMyMDAxOTk="*/);
SendAndRecvMsg(sockClient, str, lstrlen(str), 0, buff, MAXSIZE); //傳送使用者名稱，並接收伺服器的返回
StringToBase64(password, base);
memset(str, 0, 1024);
sprintf(str, "%s\r\n", base);
SendAndRecvMsg(sockClient, str, lstrlen(str),0, buff, MAXSIZE); //傳送使用者密碼，並接收伺服器的返回
char MailFrom[256] = {0};
sprintf(MailFrom, "MAIL FROM: <%s>\r\n", userName);
SendAndRecvMsg(sockClient, MailFrom, lstrlen(MailFrom), 0, buff, MAXSIZE);
char RcptTo[256] = {0};
sprintf(RcptTo, "RCPT TO: <%s>\r\n", targetEmail);
SendAndRecvMsg(sockClient, RcptTo, lstrlen(RcptTo), 0, buff, MAXSIZE);
SendAndRecvMsg(sockClient, "DATA\r\n", lstrlen("DATA\r\n"), 0, buff, MAXSIZE);
char Email[1024] = {0};
FormatEmail(userName, targetEmail, emailTitle, content, Email);
SendAndRecvMsg(sockClient,Email,lstrlen(Email), 0, buff, MAXSIZE);
SendAndRecvMsg(sockClient,"QUIT\r\n", lstrlen("QUIT\r\n"), 0, buff, MAXSIZE);
closesocket(sockClient);
WSACleanup();
}