使用C发送电子邮件

Question

我刚刚开始学习socket编程并了解了winsock并取得了一些进展.我的问题基本上是:我想发送电子邮件,我该怎么办？

要点:

1. 我学会了初始化winsock.SMTP端口(25).成功创建和连接套接字.我现在应该怎么做？!!!(我被困在这里)
2. 我不想要一个准备工作的代码.我想学.因此,需要任何书籍,文档,教程或文章建议.
3. 我知道C本身对网络一无所知,这是否意味着我必须下载一些库？(我使用的是VS2010,Windows 7)

这是我到目前为止阅读的页面的链接:

基本winsock指南:http://msdn.microsoft.com/en-us/library/windows/desktop/ms737629( v = vs.85).aspx

我已经阅读了beej guide的前14页(无法发布链接,新用户最多只能发布两个超链接)

我已经了解了类型(WSADATA,addrinfo structure,sockaddr,SOCKET)和功能(WSAStartup(),WSACleanup(),getaddrinfo(),Shutdown(),WSAGetLastError(),socket(),...)

我刚刚开始阅读这篇关于http://www.faqs.org/rfcs/rfc821.html的文章SMTP

这是我到现在所写的:

#include <stdio.h>
#include <WinSock2.h>
#include <WS2tcpip.h>

#pragma comment(lib, "Ws2_32.lib") // Applications that use Winsock must be linked with the Ws2_32.lib library file.

#define HTTP_PORT "80"
#define SMTP_PORT "25"
#define HOSTNAME_PORT "101"

/*
All ports and web services names ( which are string aliases of the ports

 can be found here:
 %WINDIR%\system32\drivers\etc\services

 */

int main(void)
{
    WSADATA wsdata;
    int iresult, retval; //iresult : instant result
    SOCKET connect_socket;
    struct addrinfo *result, *ptr, hints;

    iresult = WSAStartup(MAKEWORD(2, 2), &wsdata);
    if(iresult != 0) printf("Initiation of Winsock succeeded.\n");
    else
    {
        printf("WinSock initialization failed..\n");
        WSACleanup();
        return 0;
    }

    if(LOBYTE(wsdata.wVersion) == 2 && HIBYTE(wsdata.wVersion) == 2) printf("winsock.dll is found.\n");
    else
    {
        printf("Can not find the required winsock.dll file.\n");
        WSACleanup();
        return 0;
    }

    ZeroMemory(&hints, sizeof(hints));
    hints.ai_family = AF_UNSPEC; // IPv4 or IPv6
    hints.ai_protocol = IPPROTO_TCP; // TCP connection ( full duplex )
    hints.ai_socktype = SOCK_STREAM; // Provides sequenced, reliable, two-way, connection-based byte streams

    connect_socket = socket(hints.ai_family, hints.ai_socktype, hints.ai_protocol);
    if(connect_socket == INVALID_SOCKET)
    {
        printf("Socket Creation failed..\n");
        WSACleanup();
        return 0;
    }
    else printf("Socket Creation Succeeded ..\n");
    WSACleanup();
    return 1;
}

我离开了吗？

Answer 1

您应该通过 telnet查看一些有关 smtp 的示例：)

基本上，您需要以纯文本形式输入如下内容：

HELO local.domain.name 
MAIL FROM: mail@domain.ext
RCPT TO: mail@otherdomain.ext
DATA
...

根据这个例子编辑，你的代码应该是：

// Not sure about this one, maybe just "\n"
#define  SEPARATOR "\n\r"

int sendData( Socket *socket, const char *data) {
    int iResult;
    iResult = send(socket, data, (int) strlen(data), 0);
    if(iResult == SOCKET_ERROR){
      // Do error handling as you like
    }
    return iResult;
}

sendData( socket, "HELO local.doman.name" SEPARATOR);
sendData( socket, "MAIL FROM: mail@domain.ext" SEPARATOR);
sendData( socket, "RCPT TO: mail@otherdomain.ext" SEPARATOR);
sendData( socket, "DATA" SEPARATOR);
sendData( socket, "This is subject of my mail" SEPARATOR SEPARATOR);
sendData( socket, "And this is text" SEPARATOR);
sendData( socket, "." SEPARATOR); // Send mail