在OSI參考模型中Http與Https均屬於應用層協議。Http即Hypertext Transfer Protocol，超文本傳輸協議；而Https為Secure Hypertext Transfer Protocol安全超文本傳輸協議，它是一個安全通信通道，基於HTTP開發，用於在客戶端與服務器之間交換信息，它使用安全套接字層SSL進行信息交換，簡單來說它就是HTTP的安全版。
Http默認使用80端口，Https使用443端口。
Http的數據在網絡上是明文傳輸，而Https則是通過加密後的傳輸，因此它相比http會更加安全，但是由於需要額外加解密操作，因為Https的效率沒有那麼高。在登錄Https站點和Http站點時，可以明顯感覺到性能差異。
當前許多的web站點登錄時都是采用普通的http進行傳輸，這種方式有著極大的安全隱患。當前web開發登錄系統常用的有以下四種方式：
1) 賬號和密碼完全沒有加密，明文傳送。這種方式的安全級別是最低的，它無疑是將自己的賬號和密碼直接暴露給別人，通過抓包工具（例：WireShark）可以很容易的截獲到賬號和密碼。
2) 密碼采用MD5或其它加密方式進行加密，聲稱不可破解。其實，完全沒有必要破解，只要截獲加密後的密碼串，就可以以你的身份訪問服務器，這樣也是可以通過認證授權的。這種方式在加密程度上有了一定程度的提高，但仍是不安全的。
3) 客戶端在登錄前去服務端拿一次密鑰，通過該密鑰進行加密，而服務器端的密鑰是隨機生成的，每次訪問均會用不同的密鑰。這種方式的安全性比較高。
4) 采用“安全性最高”的HTTPS方式傳輸，客戶端與服務端會經過認證，且中間的傳輸數據全部進行加密。之所以在安全性最高上加引號，是因為它也不是絕對安全的，比如前段時間Openssl曝出安全漏洞，大名鼎鼎的“心髒出血”，黑客利用它的一個memcpy的bug，可以從溢出的內存中拿到64K的用戶數據，導致用戶信息洩露。但是這個安全性級別相對前面三個是最高的，當前服務端的證書一年收費大約3-5千，用這點錢換來相對安全，是很劃算的事情了。
無論是Http還是Https都是基於TCP進行傳輸的，因此使用SOCKET模擬HTTP訪問web站點的方式，很簡單，就是將頭部數據拼接成數據包，發送給服務端，然後接收返回再解析就可以了。
其基本流程和編寫普通SOCKET通信是一樣的。Windows下的流程為：
a. WSAStartup對Winsock服務進行初始化
b. 建立socket套接字
c. connect連接服務端
d. send發送數據
e. recv接收數據
下面，以某站點的登錄為例，利用Fiddler抓到的POST的頭部信息如下：
這樣，我們就可以構建這樣的數據包發送出去，然後接收響應了，C++實現核心代碼請見下部分。
BOOL SocketClient::ConnectToServer(const CString strServerUrl, const int nPort)
{
cstrServerUrl = strServerUrl;
nServerPort = nPort;
BOOL bRet = FALSE;
do
{
if (!InitializeContext())
{
break;
}
if(!Connect())
{
break;
}
bRet = TRUE;
} while (FALSE);
return bRet;
}
BOOL SocketClient::LoginToServer(const CString strUsername, const CString strPasswd)
{
cstrUserName = strUsername;
cstrPassWord = strPasswd;
BOOL bRet = FALSE;
do
{
if (!SendPostData())
{
break;
}
bRet = TRUE;
} while (FALSE);
return bRet;
}
BOOL SocketClient::LogoutOfServer()
{
return FALSE;
}
BOOL SocketClient::InitializeContext()
{
BOOL bRet = FALSE;
wsaData = new WSADATA;
WORD wVersion = MAKEWORD(2, 2);
do
{
if(0 != WSAStartup(wVersion, wsaData))
{
break;
}
if(LOBYTE( wsaData->wVersion ) != 2 || HIBYTE( wsaData->wVersion ) != 2 )
{
WSACleanup();
break;
}
LPHOSTENT lpHostTent;
lpHostTent = gethostbyname(cstrServerUrl);
if (NULL == lpHostTent)
{
break;
}
socketClient = socket(AF_INET, SOCK_STREAM, IPPROTO_TCP);
if (socketClient == INVALID_SOCKET)
{
WSACleanup();
break;
}
socketAddrClient = new SOCKADDR_IN;
socketAddrClient->sin_family = AF_INET;
socketAddrClient->sin_port = htons(nServerPort);
socketAddrClient->sin_addr = *((LPIN_ADDR)*lpHostTent->h_addr_list);
memset(socketAddrClient->sin_zero, 0, sizeof(socketAddrClient->sin_zero));
bRet = TRUE;
} while (FALSE);
return bRet;
}
BOOL SocketClient::Connect()
{
BOOL bRet = FALSE;
do
{
if (SOCKET_ERROR == connect(socketClient, (LPSOCKADDR)socketAddrClient, sizeof(SOCKADDR_IN)))
{
int nErrorCode = WSAGetLastError();
closesocket(socketClient);
break;
}
bRet = TRUE;
} while (FALSE);
return bRet;
}
BOOL SocketClient::SendPostData()
{
CString cstrSendData;
CString cstrSendParam = redirect=&username=+cstrUserName+&password=+cstrPassWord+&auto_login=checked&submit=%E7%99%BB%E5%BD%95;
BOOL bRet = FALSE;
CString cstrSendParamLen;
cstrSendParamLen.Format(%d, cstrSendParam.GetLength());
cstrSendData = POST http://account.vsochina.com/user/login HTTP/1.1
;
cstrSendData += Host: account.vsochina.com
;
cstrSendData += User-Agent: Mozilla/5.0 (Windows NT 6.3; WOW64; rv:35.0) Gecko/20100101 Firefox/35.0
;
cstrSendData += Accept: text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8
;
cstrSendData += Accept-Language: zh-cn,zh;q=0.8,en-us;q=0.5,en;q=0.3
;
cstrSendData += Accept-Encoding: gzip, deflate
;
cstrSendData += DNT: 1
;
cstrSendData += Referer: http://account.vsochina.com/user/login
;
cstrSendData += Connection: keep-alive
;
cstrSendData += Content-Type: application/x-www-form-urlencoded
;
cstrSendData += Content-Length: + cstrSendParamLen +
;
cstrSendData +=
;
cstrSendData += cstrSendParam;
CString cstrRecvData;
do
{
if (-1 == send(socketClient, cstrSendData.GetBuffer(), cstrSendData.GetLength(), 0))
{
break;
}
char recvData[1000] = {0};
int nRecvLen;
while((nRecvLen = recv(socketClient, recvData, sizeof(recvData), 0)) > 0)
{
cstrRecvData += recvData;
}
if (cstrRecvData.GetLength() == 0)
{
break;
}
ParseCookieFromRecvData(cstrRecvData);
//!判斷返回的COOKIE信息中，UID是否存在
if (cstrCookieUid.IsEmpty())
{
break;
}
bRet = TRUE;
} while (FALSE);
return bRet;
}
void SocketClient::ParseCookieFromRecvData(const CString cstrRecvData)
{
list lstCookiesLine; //!存放Set-Cookie的一行，例：Set-Cookie: vso_uname=houqd_1111;
CString cstrFind = Set-Cookie:; //!查找標記
CString cstrSeperator =
; //!以
分割號來分割字符串
int nPos = 0;
int nStart = cstrRecvData.Find(cstrSeperator);
while(nStart != -1)
{
CString cstrSessionLine = cstrRecvData.Mid(nPos, nStart - nPos + 1);
if (cstrSessionLine.Find(cstrFind) != -1)
{
CString cstrRealRecord = cstrSessionLine.Right(cstrSessionLine.GetLength() - cstrFind.GetLength() - 3);
list::iterator it = find(lstCookiesLine.begin(), lstCookiesLine.end(), cstrRealRecord);
if (it == lstCookiesLine.end())
{
lstCookiesLine.push_back(cstrRealRecord);
}
}
nPos = nStart;
nStart = cstrRecvData.Find(cstrSeperator, nPos + 2);
}
//!根據每行獲取的cookie值，解析為key-value的形式
vector vecCookieSet;
for (list::iterator it = lstCookiesLine.begin(); it != lstCookiesLine.end(); it++)
{
CString cstrCookies = *it;
CString cstrSeperator = ;;
StaticUtility::StringSplit(cstrCookies, cstrSeperator, vecCookieSet);
}
vector vecTemp;
for (vector::iterator it = vecCookieSet.begin(); it != vecCookieSet.end(); it++)
{
vecTemp.clear();
CString cstrOneCookies = *it;
CString cstrSeperator = =;
StaticUtility::StringSplit(cstrOneCookies, cstrSeperator, vecTemp);
CString cstrKey = vecTemp[0];
CString cstrVal = vecTemp[1];
if(cstrKey.Compare(vso_uid) == 0)
{
cstrCookieUid = cstrVal;
break;
}
}
}
通過接收來的頭部信息中，將cookie信息解析出來，就可以判斷是否登錄成功了。然後，如果有或許的操作，在請求中掛上這些cookie信息，就可以獲取想要的數據，完成想要的操作了。
HTTPS=HTTP + SSL，因此利用OpenSSL發送請求給HTTPS站點和第二章的SOCKET發送HTTP是非常相似的，只不過要在原生的套接字上套上SSL層，基本流程如下：
a. WSAStartup對Winsock服務進行初始化
b. 建立socket套接字
c. connect連接服務端
d. 建立SSL上下文
e. 建立SSL
f. 將SSL與前面建立的socket套接字綁定
g. SSL_write()發送數據
h. SSL_read()接收數據
下面以小米官網站點的登錄為例，來展示利用OpenSSL如何訪問HTTPS站點，模擬登陸，核心代碼，見下一章節。
#pragma comment( lib, libeay32.lib )
#pragma comment( lib, ssleay32.lib )
HttpsClient::HttpsClient(void):
wsaData(NULL),
socketAddrClient(NULL),
ssl(NULL),
sslCtx(NULL),
sslMethod(NULL),
serverCertification(NULL)
{
SSL_load_error_strings();
SSLeay_add_ssl_algorithms();
}
HttpsClient::~HttpsClient(void)
{
//!清理打開的句柄
if (NULL != ssl)
{
SSL_shutdown(ssl);
closesocket(socketClient);
SSL_free(ssl);
ssl = NULL;
}
if (NULL != sslCtx)
{
SSL_CTX_free(sslCtx);
}
WSACleanup();
}
BOOL HttpsClient::ConnectToServer(const CString strServerUrl, const int nPort)
{
cstrServerUrl = strServerUrl;
nServerPort = nPort;
BOOL bRet = FALSE;
do
{
if (!InitializeSocketContext())
{
break;
}
if (!SocketConnect())
{
break;
}
if (!InitializeSslContext())
{
break;
}
if (!SslConnect())
{
break;
}
bRet = TRUE;
} while (FALSE);
return bRet;
}
BOOL HttpsClient::LoginToServer(const CString strUsername, const CString strPasswd)
{
cstrUserName = strUsername;
cstrPassWord = strPasswd;
BOOL bRet = FALSE;
do
{
if (!SendLoginPostData())
{
break;
}
CString cstrRecvData;
RecvLoginPostData(cstrRecvData);
if (cstrRecvData.GetLength() == 0)
{
break;
}
ParseCookieFromRecvData(cstrRecvData);
if (cstrCookieUid.IsEmpty() || cstrCookieUid.Compare(EXPIRED) == 0)
{
break;
}
bRet = TRUE;
} while (FALSE);
return bRet;
}
BOOL HttpsClient::LogoutOfServer()
{
return FALSE;
}
BOOL HttpsClient::InitializeSocketContext()
{
//!初始化winSocket環境
BOOL bRet = FALSE;
wsaData = new WSADATA;
WORD wVersion = MAKEWORD(2, 2);
do
{
if(0 != WSAStartup(wVersion, wsaData))
{
break;
}
if(LOBYTE( wsaData->wVersion ) != 2 || HIBYTE( wsaData->wVersion ) != 2 )
{
WSACleanup();
break;
}
LPHOSTENT lpHostTent;
lpHostTent = gethostbyname(cstrServerUrl);
if (NULL == lpHostTent)
{
break;
}
socketClient = socket(AF_INET, SOCK_STREAM, IPPROTO_TCP);
if (socketClient == INVALID_SOCKET)
{
WSACleanup();
break;
}
socketAddrClient = new SOCKADDR_IN;
socketAddrClient->sin_family = AF_INET;
socketAddrClient->sin_port = htons(nServerPort);
socketAddrClient->sin_addr = *((LPIN_ADDR)*lpHostTent->h_addr_list);
memset(socketAddrClient->sin_zero, 0, sizeof(socketAddrClient->sin_zero));
bRet = TRUE;
} while (FALSE);
return bRet;
}
BOOL HttpsClient::SocketConnect()
{
//!原生socket連接
BOOL bRet = FALSE;
do
{
if (SOCKET_ERROR == connect(socketClient, (LPSOCKADDR)socketAddrClient, sizeof(SOCKADDR_IN)))
{
int nErrorCode = WSAGetLastError();
closesocket(socketClient);
break;
}
bRet = TRUE;
} while (FALSE);
return bRet;
}
BOOL HttpsClient::InitializeSslContext()
{
//!SSL通信初始化
BOOL bRet = FALSE;
do
{
sslMethod = SSLv23_client_method();
if(NULL == sslMethod)
{
break;
}
sslCtx = SSL_CTX_new(sslMethod);
if (NULL == sslCtx)
{
break;
}
ssl = SSL_new(sslCtx);
if (NULL == ssl)
{
break;
}
bRet = TRUE;
} while (FALSE);
return bRet;
}
BOOL HttpsClient::SslConnect()
{
//!SSL綁定原生socket,並連接服務器
BOOL bRet = FALSE;
do
{
SSL_set_fd(ssl, socketClient);
int nRet = SSL_connect(ssl);
if (-1 == nRet)
{
break;
}
bRet = TRUE;
} while (FALSE);
return bRet;
}
BOOL HttpsClient::SslGetCipherAndCertification()
{
BOOL bRet = FALSE;
do
{
cstrSslCipher = SSL_get_cipher(ssl);
serverCertification = SSL_get_certificate(ssl);
if (NULL == serverCertification)
{
break;
}
cstrSslSubject = X509_NAME_oneline(X509_get_subject_name(serverCertification), 0, 0);
cstrSslIssuer = X509_NAME_oneline(X509_get_issuer_name(serverCertification), 0, 0);
X509_free(serverCertification);
bRet = TRUE;
} while (FALSE);
return bRet;
}
BOOL HttpsClient::SendLoginPostData()
{
CString cstrSendData;
//CString cstrSendParam = redirect=&username=+cstrUserName+&password=+cstrPassWord+&auto_login=checked&submit=%E7%99%BB%E5%BD%95;
CString cstrSendParam = user=+cstrUserName+&_json=true&pwd=+cstrPassWord+&callback=http%3A%2F%2Forder.mi.com%2Flogin%2Fcallback%3Ffollowup%3Dhttp%253A%252F%252Fwww.mi.com%252F%26sign%3DNWU4MzRmNjBhZmU4MDRmNmZkYzVjMTZhMGVlMGFmMTllMGY0ZTNhZQ%2C%2C&sid=mi_eshop&qs=%253Fcallback%253Dhttp%25253A%25252F%25252Forder.mi.com%25252Flogin%25252Fcallback%25253Ffollowup%25253Dhttp%2525253A%2525252F%2525252Fwww.mi.com%2525252F%252526sign%25253DNWU4MzRmNjBhZmU4MDRmNmZkYzVjMTZhMGVlMGFmMTllMGY0ZTNhZQ%25252C%25252C%2526sid%253Dmi_eshop&hidden=&_sign=%2Bw73Dr7cAfRlMfOR6fW%2BF0QG4jE%3D&serviceParam=%7B%22checkSafePhone%22%3Afalse%7D&captCode=;
BOOL bRet = FALSE;
CString cstrSendParamLen;
cstrSendParamLen.Format(%d, cstrSendParam.GetLength());
cstrSendData = POST https://account.xiaomi.com/pass/serviceLoginAuth2 HTTP/1.1
;
cstrSendData += Host: account.xiaomi.com
;
cstrSendData += User-Agent: Mozilla/5.0 (Windows NT 6.3; WOW64; rv:35.0) Gecko/20100101 Firefox/35.0
;
cstrSendData += Accept: text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8
;
cstrSendData += Accept-Language: zh-cn,zh;q=0.8,en-us;q=0.5,en;q=0.3
;
cstrSendData += Accept-Encoding: gzip, deflate
;
cstrSendData += DNT: 1
;
cstrSendData += Content-Type: application/x-www-form-urlencoded; charset=UTF-8
;
cstrSendData += Referer: https://account.xiaomi.com/pass/serviceLogin?callback=http%3A%2F%2Forder.mi.com%2Flogin%2Fcallback%3Ffollowup%3Dhttp%253A%252F%252Fwww.mi.com%252Findex.html%26sign%3DNDRhYjQwYmNlZTg2ZGJhZjI0MTJjY2ZiMTNiZWExODMwYjkwNzg2ZQ%2C%2C&sid=mi_eshop
;
cstrSendData += Content-Length: + cstrSendParamLen +
;
cstrSendData += Connection: keep-alive
;
cstrSendData +=
;
cstrSendData += cstrSendParam;
CString cstrRecvData;
do
{
int nRet = SSL_write(ssl, cstrSendData, cstrSendData.GetLength());
if(-1 == nRet)
{
break;
}
bRet = TRUE;
} while (FALSE);
return bRet;
}
void HttpsClient::RecvLoginPostData(CString &cstrRecvData)
{
BOOL bRet = FALSE;
do
{
TIMEVAL tval;
tval.tv_sec = 20;
tval.tv_usec = 0;
while(TRUE)
{
FD_SET fds;
FD_ZERO(&fds);
FD_SET(socketClient, &fds);
char recvData[1000] = {0};
int nRecvLen;
//int nSelect = select(FD_SETSIZE, &fds, NULL, NULL, &tval);
//if (1 != nSelect)
//{
// break;
//}
int nErr = SSL_read(ssl, recvData, sizeof(recvData));
if (nErr <= 0)
{
break;
}
cstrRecvData += recvData;
}
if (cstrRecvData.GetLength() == 0)
{
break;
}
bRet = TRUE;
} while (FALSE);
}
void HttpsClient::ParseCookieFromRecvData(const CString cstrRecvData)
{
list lstCookiesLine; //!存放Set-Cookie的一行，例：Set-Cookie: vso_uname=houqd_1111;
CString cstrFind = Set-Cookie:; //!查找標記
CString cstrSeperator =
; //!以
分割號來分割字符串
int nPos = 0;
int nStart = cstrRecvData.Find(cstrSeperator);
while(nStart != -1)
{
CString cstrSessionLine = cstrRecvData.Mid(nPos, nStart - nPos + 1);
if (cstrSessionLine.Find(cstrFind) != -1)
{
CString cstrRealRecord = cstrSessionLine.Right(cstrSessionLine.GetLength() - cstrFind.GetLength() - 3);
list::iterator it = find(lstCookiesLine.begin(), lstCookiesLine.end(), cstrRealRecord);
if (it == lstCookiesLine.end())
{
lstCookiesLine.push_back(cstrRealRecord);
}
}
nPos = nStart;
nStart = cstrRecvData.Find(cstrSeperator, nPos + 2);
}
//!根據每行獲取的cookie值，解析為key-value的形式
vector vecCookieSet;
for (list::iterator it = lstCookiesLine.begin(); it != lstCookiesLine.end(); it++)
{
CString cstrCookies = *it;
CString cstrSeperator = ;;
StaticUtility::StringSplit(cstrCookies, cstrSeperator, vecCookieSet);
}
vector vecTemp;
for (vector::iterator it = vecCookieSet.begin(); it != vecCookieSet.end(); it++)
{
vecTemp.clear();
CString cstrOneCookies = *it;
CString cstrSeperator = =;
StaticUtility::StringSplit(cstrOneCookies, cstrSeperator, vecTemp);
CString cstrKey;
CString cstrVal;
if (vecTemp.size() == 2)
{
cstrKey = vecTemp[0];
cstrVal = vecTemp[1];
}
if(cstrKey.Compare(userId) == 0)
{
cstrCookieUid = cstrVal;
break;
}
}
}
同理，判斷登錄也是在返回的信息中拿cookie信息，再進行下一步操作。
