Objectarx uses libcurl to request WebApi

Because developing CAD requires requesting data from the server, I set up a webapi user on the server to transfer data, so I installed libcurl to use the data in objectarx.
Open VS2012 x64 Native Tools Command PromptSupplementary address:

I will quote the relevant configuration pictures here, and the application in CAD is consistent with the conventional one.
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All usage is consistent with the current case, but an error occurred here. I will record it here. In the following code, I ran the program and CAD reported an error memory leak. After locating the problem, I found that the problem was in this sentence.

CURLcode res = curl_easy_perform(curl);

I checked many articles but couldn't solve it. Later I found out that it was actually a data transfer error here, and my pointer transfer error caused the problem.
Here is the problem code snippet a>

inline BOOL webApi::DownloadFile(const char* Filepath)
{
    // ...

    curl_easy_setopt(curl, CURLOPT_URL, combinePath.c_str());
    curl_easy_setopt(curl, CURLOPT_WRITEFUNCTION, &webApi::curlWriteFunction);
    curl_easy_setopt(curl, CURLOPT_WRITEDATA, fp);
    CURLcode result = curl_easy_perform(curl);

    fclose(fp);
    curl_easy_cleanup(curl);

    curl_global_cleanup();

    return TRUE;
}

You can see that in this code I passed in a pointer

  curl_easy_setopt(curl, CURLOPT_WRITEFUNCTION, &webApi::curlWriteFunction);

The problem occurs here because what needs to be called here is the callback function pointer, but the instance function pointer is used in my code, resulting in a value transfer error, which leads to subsequent problems.
Modify here to:

webapi.h
static size_t downloadCallback(void *buffer, size_t sz, size_t nmemb, void *writer);

webapi.cpp
size_t webApi::downloadCallback(void* buffer, size_t sz, size_t nmemb, void* writer)
{
	std::string* psResponse = (std::string*)writer;
	size_t size = sz * nmemb;
	psResponse->append((char*)buffer, size);

	return sz * nmemb;
}

Then modify the original code snippet:

std::string strTmpStr;
CURL *curl = curl_easy_init();
curl_easy_setopt(curl, CURLOPT_URL, strUrl.c_str());
curl_easy_setopt(curl, CURLOPT_NOSIGNAL, 1L);
curl_easy_setopt(curl, CURLOPT_TIMEOUT, 20);
curl_easy_setopt(curl, CURLOPT_WRITEFUNCTION, downloadCallback); 
curl_easy_setopt(curl, CURLOPT_WRITEDATA, &strTmpStr);
CURLcode res = curl_easy_perform(curl);
curl_easy_cleanup(curl);
std::string strRsp;

problem solved.

Objectarx uses libcurl to request WebApi

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