WinHttp编程初步心得

代码都在下面了，目前这个版本实现的功能还非常的少，能实现的有：

1. GET方法。给定一个URL（可以带中文），返回http的响应数据，包括文本和二进制数据
2. 支持代理服务器，需要用户预先设定好proxy server ip, port, username, password.

不支持的有：
1. POST
2. 查询http响应的header。
3. 将返回的文本数据重新编码，变成UTF-16。这需要首先从header取出http server响应的数据是什么编码的，然后就可以使用windows的MultiByteToWideChar来进行转换。

这里总结几点开发过程中的注意点：
1. MSDN上的资料不是非常的全，所以有些参考了google得来的内容。
2. WinHttpOpen的时候，如果用AUTO PROXY，也就是让winhttp从注册表读取proxy设置的话（这个注册表的设置是proxycfg.exe生成的，和IE中的那个proxy设置是两码事）。
3. proxy的用户名和密码需要用WinHttpSetOption来进行设置, timeout设定用WinHttpSetTimeouts
4. 使用WinHttpCrackUrl可以将一个给定的url（必须以http://, https://打头）分解，设置到URL_COMPONENTS这个structure中。在这里其实就可以做url encoding（也就是将url不支持的字符转换成%xxx这样的东西），但是这样做的话需要手动给URL_COMPONENETS中的member分 配内存，比较麻烦，所以没做。
5. 使用WinHttpCreateUrl可以根据URL_COMPONENETS重新生成一个string的URL，但是这里没用到。
6. 使用WinHttpConnect的时候，一定要注意要给出hostname，不是url，所以要手动分解，只取出http server的那个部分，比如http://www.google.com/sfsdfdsf?id=xxx& user=xxxx，hostname就是www.google.com
7. 然后使用WinHttpOpenRequest的时候，就可以给出去掉了http://之后的后面所有内容了，也就是www.google.com /sfsdfdsf?id=xxx&user=xxxx这样的东西。注意最后的flag设 置：WINHTTP_FLAG_ESCAPE_PERCENT | WINHTTP_FLAG_REFRESH，这两个很有用，WINHTTP_FLAG_ESCAPE_PERCENT就是将url中不合法的内容转 成%xxx，WINHTTP_FLAG_REFRESH就是跳过proxy的cache，每次都请求全新的数据。还有需要注意的 是，WinHttpOpenRequest中，要求给出我们能接受的mimetype，这里可以参考代码，如果要文本，就给text/*，如果要二进制数 据，就可以像这里给出application/*, image/*, audio/*......
8. 最后WinHttpSendRequest的时候，也可以设定additional header和optional数据。这里的optional数据一般是用于POST的，也就是将需要post到server的数据填充在这个地方。 WinHttpSendRequest将header都发送出去之后，紧接着就会发送这个optional数据。
9. WinHttpQueryDataAvailable可以check是否还有数据需要接收。WinHttpReadData用来读取数据，注意读出来的数 据就是字节流，像前面所说，如果是文本，那么要根据response header，首先知道是什么编码和字符集，然后再用MultiByteToWideChar来转换。也要注意WinHttpReadData的最后一个 参数，给出了实际读取到的字节数，也可以根据这个信息来判断是否已经接收完了。此外特别需要注意的是，如果用的是一个固定的buffer循环接收，就像这 里一样，那么不要忘记接收完成的时候，要在尾部加上\0，分配buffer的时候也要留出\0的位置。

    /*
    * Schedule Download Http utilities, based on winhttp
    * Written by Eric Zhang <nicolas.m.zhang@gmail.com>
    */

    #include "..\include\http.h"
    #include "..\include\logger.h"
    #include "..\include\utils.h"
    #include "..\include\defs.h"
    #include "..\include\macros.h"
    #include <strsafe.h>

    // http server's hostname length
    #define HTTP_HOST_NAME_MAX      255
    #define HTTP_TEXT_MIMETYPE      1
    #define HTTP_BIN_MIMETYPE      2

    // mimetypes for WinHttpOpenRequest
    LPCWSTR text_mimetype[] = { L"text/*", L"\0" };
    LPCWSTR bin_mimetype[] = { L"application/*", L"audio/*", L"image/*", L"video/*", L"\0" };

    /*
    * This function used internally. It checks the proxy settings and apply
    * to the WinHttp. Return winhttp session handle if succeeded, otherwise
    * return NULL.
    */
    static HINTERNET open_winhttp()
    {
       HINTERNET session = NULL;
       TCHAR proxy_enabled[REGISTRY_VALUE_SIZE];
       TCHAR proxy_server[REGISTRY_VALUE_SIZE];
       TCHAR proxy_port[REGISTRY_VALUE_SIZE];
       TCHAR proxy_username[REGISTRY_VALUE_SIZE];
       TCHAR proxy_password[REGISTRY_VALUE_SIZE];
       DWORD errcode;
       size_t proxy_username_len = 0;
       size_t proxy_password_len = 0;

       // Check whether the proxy has enabled
       SecureZeroMemory(proxy_enabled, sizeof(proxy_enabled));
       utils_get_registry_value(SD_REGISTRY_KEY, HTTP_PROXY_ENABLED_ENTRY, proxy_enabled, sizeof(proxy_enabled));
       if (utils_is_string_empty(proxy_enabled) || _tcscmp(proxy_enabled, TEXT("Y")) != 0) {
          // proxy isn't enabled, direct connect
          session = WinHttpOpen(HTTP_AGENT_NAME, WINHTTP_ACCESS_TYPE_NO_PROXY, WINHTTP_NO_PROXY_NAME, WINHTTP_NO_PROXY_BYPASS, 0);
          if (session == NULL) {
             GET_ERROR_CODE(errcode);
             M_GTIF_WITH_LOG(FALSE, failed, LOG_LEVEL_ERROR, __SDFILE__, __LINE__, HTTP_NO_PROXY_OPEN_FAILED, utils_format_error_string(errcode));
          }
       } else {
          // proxy enabled, read server/port/user/pass next
          SecureZeroMemory(proxy_server, sizeof(proxy_server));
          SecureZeroMemory(proxy_port, sizeof(proxy_port));
          SecureZeroMemory(proxy_username, sizeof(proxy_username));
          SecureZeroMemory(proxy_password, sizeof(proxy_password));
          utils_get_registry_value(SD_REGISTRY_KEY, HTTP_PROXY_SERVER_ENTRY, proxy_server, sizeof(proxy_server));
          utils_get_registry_value(SD_REGISTRY_KEY, HTTP_PROXY_PORT_ENTRY, proxy_port, sizeof(proxy_port));
          utils_get_registry_value(SD_REGISTRY_KEY, HTTP_PROXY_USER_ENTRY, proxy_username, sizeof(proxy_username));
          utils_get_registry_value(SD_REGISTRY_KEY, HTTP_PROXY_PASS_ENTRY, proxy_password, sizeof(proxy_password));
          M_GTIF_WITH_LOG(!utils_is_string_empty(proxy_server), failed, LOG_LEVEL_ERROR, __SDFILE__, __LINE__, HTTP_PROXY_SERVER_ABSENT);
          M_GTIF_WITH_LOG(!utils_is_string_empty(proxy_port), failed, LOG_LEVEL_ERROR, __SDFILE__, __LINE__, HTTP_PROXY_PORT_ABSENT);
          M_GTIF_WITH_LOG(utils_is_string_int(proxy_port), failed, LOG_LEVEL_ERROR, __SDFILE__, __LINE__, HTTP_PROXY_PORT_ILLEGAL);
          // add port into server string
          M_GTIF_WITH_LOG(SUCCEEDED(StringCchPrintf(proxy_server, _countof(proxy_server), TEXT("%s:%s"), proxy_server, proxy_port)), failed,
             LOG_LEVEL_ERROR, __SDFILE__, __LINE__, HTTP_STRING_OPERATION_FAILED);

          // open
          session = WinHttpOpen(HTTP_AGENT_NAME, WINHTTP_ACCESS_TYPE_NAMED_PROXY, proxy_server, WINHTTP_NO_PROXY_BYPASS, 0);
          if (session == NULL) {
             GET_ERROR_CODE(errcode);
             M_GTIF_WITH_LOG(FALSE, failed, LOG_LEVEL_ERROR, __SDFILE__, __LINE__, HTTP_OPEN_WITH_PROXY_FAILED, utils_format_error_string(errcode));
          }

          // set proxy username & password
          if (!utils_is_string_empty(proxy_username) && !utils_is_string_empty(proxy_password)) {
             M_GTIF_WITH_LOG(SUCCEEDED(StringCchLength(proxy_username, _countof(proxy_username), &proxy_username_len)), failed,
                LOG_LEVEL_ERROR, __SDFILE__, __LINE__, HTTP_STRING_OPERATION_FAILED);
             M_GTIF_WITH_LOG(SUCCEEDED(StringCchLength(proxy_password, _countof(proxy_password), &proxy_password_len)), failed,
                LOG_LEVEL_ERROR, __SDFILE__, __LINE__, HTTP_STRING_OPERATION_FAILED);
             if (!WinHttpSetOption(session, WINHTTP_OPTION_PROXY_USERNAME, proxy_username, proxy_username_len)) {
                GET_ERROR_CODE(errcode);
                M_GTIF_WITH_LOG(FALSE, failed, LOG_LEVEL_ERROR, __SDFILE__, __LINE__, HTTP_SET_PROXY_USER_FAILED, utils_format_error_string(errcode));
             }
             if (!WinHttpSetOption(session, WINHTTP_OPTION_PROXY_PASSWORD, proxy_password, proxy_password_len)) {
                GET_ERROR_CODE(errcode);
                M_GTIF_WITH_LOG(FALSE, failed, LOG_LEVEL_ERROR, __SDFILE__, __LINE__, HTTP_SET_PROXY_PASS_FAILED, utils_format_error_string(errcode));
             }
          }
       }

       // set timeouts
       if (!WinHttpSetTimeouts(session, HTTP_RESOLVE_TO, HTTP_CONNECT_TO, HTTP_SEND_TO, HTTP_RECV_TO)) {
          GET_ERROR_CODE(errcode);
          M_GTIF_WITH_LOG(FALSE, failed, LOG_LEVEL_ERROR, __SDFILE__, __LINE__, HTTP_SET_TIMEOUTS_FAILED, utils_format_error_string(errcode));
       }

       return session;
    failed:
       if (session != NULL) WinHttpCloseHandle(session);
       return NULL;
    }

    static BOOL http_get(PCTSTR url, HINTERNET *sess, HINTERNET *conn, HINTERNET *req, DWORD mimetype)
    {
       HINTERNET session = NULL, connect = NULL, request = NULL;
       BOOL result = FALSE;
       DWORD errcode;
       URL_COMPONENTS url_comp;
       size_t url_len_input;
       TCHAR http_host_name[HTTP_HOST_NAME_MAX];
       int hostname_index;

       M_RETURN_VAL_IF_FAIL(url != NULL, FALSE);
       M_RETURN_VAL_IF_FAIL(sess != NULL, FALSE);
       M_RETURN_VAL_IF_FAIL(conn != NULL, FALSE);
       M_RETURN_VAL_IF_FAIL(req != NULL, FALSE);
       M_RETURN_VAL_IF_FAIL(logger_is_enabled(), FALSE);

       session = open_winhttp();
       M_RETURN_VAL_IF_FAIL(session != NULL, FALSE);  // log has been done in open_winhttp function

       // crack url input
       // Initialize the URL_COMPONENTS structure.
        SecureZeroMemory(&url_comp, sizeof(url_comp));
        url_comp.dwStructSize = sizeof(url_comp);

        // Set required component lengths to non-zero
        // so that they are cracked.
        url_comp.dwSchemeLength    = -1;
        url_comp.dwHostNameLength  = -1;
        url_comp.dwUrlPathLength   = -1;
        url_comp.dwExtraInfoLength = -1;

       M_GTIF_WITH_LOG(SUCCEEDED(StringCchLength(url, STRSAFE_MAX_CCH, &url_len_input)), failed, LOG_LEVEL_ERROR,
          __SDFILE__, __LINE__, HTTP_STRING_OPERATION_FAILED);
       result = WinHttpCrackUrl(url, url_len_input, 0, &url_comp);
       if (!result) {
          GET_ERROR_CODE(errcode);
          M_GTIF_WITH_LOG(FALSE, failed, LOG_LEVEL_ERROR, __SDFILE__, __LINE__, HTTP_CRACK_URL_FAILED, utils_format_error_string(errcode));
       }

       /* No need to create url because No winhttp functions accept a whole escaped url
       // get new url length, allocate it
       WinHttpCreateUrl(&url_comp, 0, NULL, &url_len_cracked);
       M_GTIF_WITH_LOG(url_len_cracked > 0, failed, LOG_LEVEL_ERROR, __SDFILE__, __LINE__, HTTP_CREATE_URL_GET_LEN_FAILED);
       // the length WinHttpCreateUrl generated is wide character numbers
       url_cracked = (TCHAR *)HeapAlloc(sdc_heap, HEAP_ZERO_MEMORY, url_len_cracked * sizeof(WCHAR));
       M_GTIF_WITH_LOG(url_cracked != NULL, failed, LOG_LEVEL_ERROR, __SDFILE__, __LINE__, HTTP_HEAP_ALLOC_FAILED);
       // call create url again, this time get result url
       result = WinHttpCreateUrl(&url_comp, 0, url_cracked, &url_len_cracked);
       if (!result) {
          GET_ERROR_CODE(errcode);
          M_GTIF_WITH_LOG(FALSE, failed, LOG_LEVEL_ERROR, __SDFILE__, __LINE__, HTTP_CREATE_URL_FAILED, utils_format_error_string(errcode));
       } */

       // url OK, connect. Notice here WinHttpConnect needs Host/Server name, not the whole URL
       // Request file and parameters should be set in WinHttpOpenRequest function
       // get hostname
       hostname_index = utils_find_char(url_comp.lpszHostName, (TCHAR)'/');
       if (hostname_index < 0) {
          // not found or error occurs, use the original hostname
          connect = WinHttpConnect(session, url_comp.lpszHostName, INTERNET_DEFAULT_HTTP_PORT, 0);
       } else {
          // found "/"
          memcpy_s(http_host_name, sizeof(http_host_name), url_comp.lpszHostName, hostname_index * sizeof(TCHAR));
          http_host_name[hostname_index] = (TCHAR)'\0';
          connect = WinHttpConnect(session, http_host_name, INTERNET_DEFAULT_HTTP_PORT, 0);
       }
       if (connect == NULL) {
          GET_ERROR_CODE(errcode);
          M_GTIF_WITH_LOG(FALSE, failed, LOG_LEVEL_ERROR, __SDFILE__, __LINE__, HTTP_CONNECT_FAILED, utils_format_error_string(errcode));
       }

       if (mimetype == HTTP_TEXT_MIMETYPE) {
          request = WinHttpOpenRequest(connect, TEXT("GET"), url_comp.lpszUrlPath, NULL, WINHTTP_NO_REFERER,
                      text_mimetype, WINHTTP_FLAG_ESCAPE_PERCENT | WINHTTP_FLAG_REFRESH);
       } else {
          request = WinHttpOpenRequest(connect, TEXT("GET"), url_comp.lpszUrlPath, NULL, WINHTTP_NO_REFERER,
                      bin_mimetype, WINHTTP_FLAG_ESCAPE_PERCENT | WINHTTP_FLAG_REFRESH);
       }
       if (request == NULL) {
          GET_ERROR_CODE(errcode);
          M_GTIF_WITH_LOG(FALSE, failed, LOG_LEVEL_ERROR, __SDFILE__, __LINE__, HTTP_OPEN_REQUEST_FAILED, utils_format_error_string(errcode));
       }

        // Send the request
        result = WinHttpSendRequest(request, WINHTTP_NO_ADDITIONAL_HEADERS, 0, WINHTTP_NO_REQUEST_DATA, 0, 0, 0 );
       if (!result) {
          GET_ERROR_CODE(errcode);
          M_GTIF_WITH_LOG(FALSE, failed, LOG_LEVEL_ERROR, __SDFILE__, __LINE__, HTTP_SEND_REQUEST_FAILED, utils_format_error_string(errcode));
       }

       // Start receiving
       result = WinHttpReceiveResponse(request, NULL);
       if (!result) {
          GET_ERROR_CODE(errcode);
          M_GTIF_WITH_LOG(FALSE, failed, LOG_LEVEL_ERROR, __SDFILE__, __LINE__, HTTP_RECV_RESPONSE_FAILED, utils_format_error_string(errcode));
       }

       // OK, return
       *sess = session;
       *conn = connect;
       *req = request;
       return TRUE;

    failed:
        // Close any open handles
        if (request) WinHttpCloseHandle(request);
        if (connect) WinHttpCloseHandle(connect);
        if (session) WinHttpCloseHandle(session);
       return FALSE;
    }

    BOOL http_get_text(PCTSTR url, HINTERNET *sess, HINTERNET *conn, HINTERNET *req)
    {
       return http_get(url, sess, conn, req, HTTP_TEXT_MIMETYPE);
    }

    BOOL http_get_bin(PCTSTR url, HINTERNET *sess, HINTERNET *conn, HINTERNET *req)
    {
       return http_get(url, sess, conn, req, HTTP_BIN_MIMETYPE);
    }

    BOOL http_check_data_len(HINTERNET request, DWORD *len)
    {
       DWORD data_size = 0;
       BOOL result = FALSE;
       DWORD errcode;

       M_RETURN_VAL_IF_FAIL(request != NULL, FALSE);
       M_RETURN_VAL_IF_FAIL(len != NULL, FALSE);
       M_RETURN_VAL_IF_FAIL(logger_is_enabled(), FALSE);

       // Check the data length
       result = WinHttpQueryDataAvailable(request, &data_size);
       if (!result) {
          GET_ERROR_CODE(errcode);
          M_RVIF_WITH_LOG(FALSE, FALSE, LOG_LEVEL_ERROR, __SDFILE__, __LINE__, HTTP_QUERY_DATA_FAILED, utils_format_error_string(errcode));
       }

       M_RVIF_WITH_LOG(data_size > 0, FALSE, LOG_LEVEL_ERROR, __SDFILE__, __LINE__, HTTP_DATA_LENGTH_ILLEGAL, data_size);

       *len = data_size;
       return TRUE;
    }

    BOOL http_recv(HINTERNET request, LPVOID buffer, DWORD buffer_len, DWORD *bytes_read)
    {
       BOOL result = FALSE;
       DWORD errcode;

       M_RETURN_VAL_IF_FAIL(request != NULL, FALSE);
       M_RETURN_VAL_IF_FAIL(buffer != NULL, FALSE);
       M_RETURN_VAL_IF_FAIL(buffer_len > 0, FALSE);
       M_RETURN_VAL_IF_FAIL(bytes_read != NULL, FALSE);
       M_RETURN_VAL_IF_FAIL(logger_is_enabled(), FALSE);

       // Read the Data.
        SecureZeroMemory(buffer, buffer_len);
        result = WinHttpReadData(request, buffer, buffer_len, bytes_read);
       if (!result) {
          GET_ERROR_CODE(errcode);
          M_RVIF_WITH_LOG(FALSE, FALSE, LOG_LEVEL_ERROR, __SDFILE__, __LINE__, HTTP_READ_DATA_FAILED, utils_format_error_string(errcode));
       }

       return TRUE;
    }

    void http_close(HINTERNET *session, HINTERNET *connect, HINTERNET *request)
    {
       if (*request) WinHttpCloseHandle(*request);
       if (*connect) WinHttpCloseHandle(*connect);
       if (*session) WinHttpCloseHandle(*session);

       *session = NULL;
       *connect = NULL;
       *request = NULL;

       return;
    }

    BOOL http_check_internet(PCTSTR url)
    {
       HINTERNET session = NULL, connect = NULL, request = NULL;
       BOOL result = FALSE;
       DWORD data_len = 0;

       M_RETURN_VAL_IF_FAIL(url != NULL, FALSE);
       M_RETURN_VAL_IF_FAIL(logger_is_enabled(), FALSE);

       result = http_get_text(url, &session, &connect, &request);
       M_RETURN_VAL_IF_FAIL(result, FALSE); // logger has been done in http_send

       result = http_check_data_len(request, &data_len);
       M_RETURN_VAL_IF_FAIL(result, FALSE);

       // internet is OK, no need to receive actual data
       http_close(&session, &connect, &request);

       return TRUE;
    }