curl系列sample一

curl是一個開源的網絡協議庫，主要針對http（是否提供其他應用層協議，我沒有深究，故用一個寬鬆的語句描述我對其的認識）

curl的文檔風格很贊。 讀者可以猛擊鏈接閱讀其sample的主頁。另外幾個在我印象中，文檔風格很清晰的庫是extjs、opencv、boost、tbb。

遇到一個比較特俗的需求，有一個項目，http協議的接口不明（接口提供方沒人維護，或者說，外包給其他公司做的，後面沒人管了），僅僅有一個網頁（我需要的幾個接口混雜在web的HTML和js代碼中）

好吧，上fiddle抓包。

某一接口的抓包結果如下，爲了隱去信息，抓包結果有進行修改和調整：

POST http://192.168.0.6:8080/cgi-bin/upload.cgi HTTP/1.1
Host: 192.168.0.6:8080
Connection: keep-alive
Content-Length: 3932475
Cache-Control: max-age=0
Accept: text/html,application/xhtml+xml,application/xml;q=0.9,image/webp,*/*;q=0.8
Origin: http://192.168.0.6:8080
User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/40.0.2214.115 Safari/537.36
Content-Type: multipart/form-data; boundary=----WebKitFormBoundaryMI3QTHGZw9Rwg6G5
Referer: http://192.168.0.6:8080/api/upload_result.php
Accept-Encoding: gzip, deflate
Accept-Language: zh-CN,zh;q=0.8

------WebKitFormBoundaryMI3QTHGZw9Rwg6G5
Content-Disposition: form-data; name="filename"; filename="helloworld.cpp"
Content-Type: application/octet-stream

blablabla...file data octet-stream....

------WebKitFormBoundaryMI3QTHGZw9Rwg6G5--

好吧，這個http數據包有通過表單的形式來上傳文件流。

我Google了一下關鍵詞：form post file curl，可能是我理解不對，這個關鍵詞搜的結果不是我需要的。

鑑於http本質就是用tcp做傳輸層的特定格式字符串，故我轉而對抓包的raw數據進行分析。

經過比較多次的比較和測試，最後得出如上的http請求的curl代碼如下

int flashfw(const string &url, string &responese)
{
	int retVal = 0 ;
	CURL *curl;
	CURLM *multi_handle;
	int still_running;

	struct curl_httppost *formpost=NULL;
	struct curl_httppost *lastptr=NULL;
	struct curl_slist *headerlist=NULL;

	curl_formadd(&formpost,
		&lastptr,
		CURLFORM_COPYNAME, "filename",
		CURLFORM_FILE, "mypicture.jpg",
		CURLFORM_CONTENTTYPE, "application/octet-stream",
		CURLFORM_END);

	curl = curl_easy_init();
	multi_handle = curl_multi_init();

	if(curl && multi_handle) {
 
		struct curl_slist *chunk = NULL;
		curl_easy_setopt(curl, CURLOPT_USERAGENT, "Mozilla/5.0 (Windows NT 6.1; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/40.0.2214.115 Safari/537.36"); 
		chunk = curl_slist_append(chunk, "Connection: keep-alive");
		chunk = curl_slist_append(chunk, "DNT: 1"); 
		chunk = curl_slist_append(chunk, "Accept-Encoding: gzip, deflate");
		chunk = curl_slist_append(chunk, "Accept-Language: zh-CN,zh;q=0.8");
		curl_easy_setopt(curl, CURLOPT_POST, 1);
		
		/* set our custom set of headers */ 
		curl_easy_setopt(curl, CURLOPT_HTTPHEADER, chunk);
		curl_easy_setopt(curl, CURLOPT_URL, url.c_str());
		curl_easy_setopt(curl, CURLOPT_VERBOSE, 1L);
		curl_easy_setopt(curl, CURLOPT_HTTPPOST, formpost);
	 
		int res = curl_easy_perform(curl);
                /* get http response status */
		long http_code = 0;
		curl_easy_getinfo (curl, CURLINFO_RESPONSE_CODE, &http_code);
		retVal = http_code ;

		/* always cleanup */
		curl_easy_cleanup(curl);

		/* then cleanup the formpost chain */
		curl_formfree(formpost);

		/* free slist */
		curl_slist_free_all (headerlist);

	}

	return retVal ;

}