Ethereum: libcurl returns error code 77 when CURLOPT_SSL_VERIFYPEER is not disabled

libcurl Error Evaluation: CURLOPT_SSL_VERIFYPEER is not disabled

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When using libcurl, it is not uncommon to encounter errors that can interrupt your progress. In this article, we will explore why you receive error code 77 when trying to make a GET request with CURLOPT_SSL_VERIFYPEER disabled.

What is CURLOPT_SSL_VERIFYPEER?

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In libcurl, CURLOPT_SSL_VERIFYPEER is a flag used to verify the SSL/TLS certificate sent by the server. If this flag is not enabled, libcurl will only connect to the server if its SSL/TLS certificate matches what it sends back.

Why does this cause an error?

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When you do not enable CURLOPT_SSL_VERIFYPEER, libcurl’s connection attempt may fail due to problems with your server’s SSL/TLS certificate. If the server certificate does not match the certificate sent by libcurl, the connection will only be established if the match is successful.

Sample code:

#include 
#include 
int main() {
curl *curl;
CURL code res;
curl_global_init(cURL_GLOBAL_DEFAULT);
curl = curl_easy_init();
if (curl) {
std::string url = "
curl_easy_setopt(curl, CURLOPT_URL, url.c_str());
curl_easy_setopt(curl, CURLOPT_SSL_VERIFYPEER, 0L); // Disable verification
res = curl_easy_perform(curl);
if (res == CURLE_OK && res == CURLE_NO_ERROR) {
std::cout << "Connection established." << std::endl;
} else(res == CURLE_OK) {
std::cerr << "Error creating connection: " << curl_easy_strerror(res) << std::endl;
}
curl_easy_cleanup(curl);
}
curl_global_cleanup();
return 0;
}

In this example, we disableCURLOPT_SSL_VERIFYPEERto allow libcurl to establish a connection even when the server's SSL/TLS certificate does not match. Note that we still test the connection usingCURLE_OKandCURLE_NO_ERROR, which allow us to detect whether the connection was successfully established.

• Check the curl documentation

  : TheCURLOPT_SSL_VERIFYPEERflag in libcurl contains more detailed information about its usage and potential issues.

• Test with different URLs: Try using a different URL that requires authentication, such as

By understanding the cause of the CURLOPT_SSL_VERIFYPEER not being disabled error, you should be able to resolve this issue and successfully execute your GET request using libcurl.

Example Use Case:

Let’s say you are building a RESTful API server that returns JSON data. In this case, you can use a GET request with CURLOPT_SSL_VERIFYPEER set to 0L (disabled) to test the connection without verifying the SSL/TLS certificate sent by the client.

“`cpp

#include

#include

int main() {

curl *curl;

CURL code res;

curl_global_init(cURL_GLOBAL_DEFAULT);

curl = curl_easy_init();

if (curl) {

std::string url = “

curl_easy_setopt(curl, CURLOPT_URL, url.c_str());

res = curl_easy_perform(curl);

if (res == CURLE_OK && res == CURLE_NO_ERROR) {

std::cout << "API server connected.

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