用C写邮件收发程序

刚刚抄来的，呵呵

#include
#include
#include
#include
#pragma comment (lib,"ws2_32.lib")
//Global variable
char server[40],to[40],from[40],subject[40],data[1024],szSend[7][2048];
int times;
struct sockaddr_in sa;
void usage(char *name)
{
printf("\n%s by eyas"
　 "\n2001/2/28"
　 "\nUsage:%s "
　 "\nExample:%s 202.104.32.230 [email protected] [email protected] hello haha 100\n",
　 name,name,name);
return;
}
DWORD WINAPI SendMail(PVOID p)
{
WSADATA wsd;
int net,ret,i,j;
char szBuffer[2048];
if(WSAStartup(MAKEWORD(1,1),&wsd)!=0)
{
　printf("\nFailed to load Winsock library!ErrorCode:%d.",GetLastError());
　ExitProcess(1);
}
net=socket(AF_INET,SOCK_STREAM,IPPROTO_TCP);
if(net==INVALID_SOCKET)
{
　printf("\nsocket() failed.ErrorCode:%d.",GetLastError());
　WSACleanup();
　ExitProcess(1);
}
ret=connect(net, (struct sockaddr *) &sa, sizeof sa);
if(ret!=0)
{
　printf("\nconnect() failed.ErrorCode:%d.",GetLastError());
　closesocket(net);
　WSACleanup();
　ExitProcess(1);
}

for(j=0;j<8;j++)
{
　//receive data
　ret=recv(net,szBuffer,2048,0);
　if((ret==0) || (ret==SOCKET_ERROR))
　{
　 printf("\nrecv() failed.ErrorCode:%d.",WSAGetLastError());
　 break;
　}
　
　if(j==7)
　 break;
　echo send data
　printf("%s",szSend[j]);
　send data
　ret=send(net,szSend[j],strlen(szSend[j]),0);
　if((ret==0) || (ret==SOCKET_ERROR))
　{
　 printf("\nsend() failed.ErrorCode:%d.",WSAGetLastError());
　 break;
　}
}
//free resource
closesocket(net);
WSACleanup();
return 0;
}
int main(int argc,char **argv)
{
HANDLE hThread;
DWORD dwThreadId;
int i;
if(argc!=7)
{
　usage(argv[0]);
　return 1;
}
//gets user input
strncpy(server,argv[1],sizeof(server));
strncpy(to,argv[2],sizeof(to));
strncpy(from,argv[3],sizeof(from));
strncpy(subject,argv[4],sizeof(subject));
strncpy(data,argv[5],sizeof(data));
times=atoi(argv[6]);
strncpy((char *)&sa, "", sizeof sa);
//fill the struct
sa.sin_family=AF_INET;
sa.sin_port=htons(25);
sa.sin_addr.s_addr=inet_addr(server);
///built send data
strcpy(szSend[0],"HELO\n");
strcpy(szSend[1],"MAIL FROM:<");
strncat(szSend[1],from,sizeof(from));
strcat(szSend[1],">\n");
strcpy(szSend[2],"RCPT TO:<");
strncat(szSend[2],to,sizeof(to));
strcat(szSend[2],">\n");
strcpy(szSend[3],"DATA\n");
strcpy(szSend[4],"Subject:");
strncat(szSend[4],subject,sizeof(subject));
strcat(szSend[4],"\nFrom:");
strncat(szSend[4],from,sizeof(from));
strcat(szSend[4],"\n\n");
strncat(szSend[4],data,sizeof(data));
strcat(szSend[4],"\n.\n");
strcpy(szSend[5],"SEND\n");
strcpy(szSend[6],"QUIT\n");
for(i=0;i {
　hThread=CreateThread(NULL,0,SendMail,(PVOID)NULL,0,&dwThreadId);
　if(hThread==NULL)
　{
　 printf("\nCreate thread error.");
　 break;
　}
　Sleep(20);
　CloseHandle(hThread);
　printf("\nHave been send %d Email.",i+1);
}
printf("\nWait 5 seconds to exit.");
Sleep(5000);
printf("\nComplete.");
return 0;
}