SSL certificate expiration date on Windows - c++

Question

Can anybody provide me a C++ implementation rather simple to get SSL certificate expiration date. I have been looking online for past many hours, couldn't find anything so far. Currently I am using libcpr, and it doesn't seem to have any way to get it. I tried using the "curl" command, but that also doesn't seem to have that particular information in the output on Windows OS. The same command give the "expire date" in the output if I run it in GitBash, but not in the windows command prompt. I am new to C++.
The command below and output is from GitBash.
$ curl --insecure -vvI https://www.example.com
* SSL connection using TLSv1.3 / TLS_AES_256_GCM_SHA384
* ALPN: server accepted h2
* Server certificate:
* subject: C=US; ST=California; L=Los Angeles;
O=Internet▒Corporation▒for▒Assigned▒Names▒and▒Numbers; CN=www.example.org
* start date: Mar 14 00:00:00 2022 GMT
* expire date: Mar 14 23:59:59 2023 GMT <-------- **********
* issuer: C=US; O=DigiCert Inc; CN=DigiCert TLS RSA SHA256 2020 CA1
* SSL certificate verify result: unable to get local issuer certificate (20),
continuing anyway.
* Using HTTP2, server supports multiplexing
* Copying HTTP/2 data in stream buffer to connection buffer after upgrade: len=0
* h2h3 [:method: HEAD]
* h2h3 [:path: /]
* h2h3 [:scheme: https]
* h2h3 [:authority: www.example.com]
* h2h3 [user-agent: curl/7.83.0]
* h2h3 [accept: */*]
* Using Stream ID: 1 (easy handle 0x16d9a46c1d0)
* TLSv1.3 (IN), TLS handshake, Newsession Ticket (4):
* TLSv1.3 (IN), TLS handshake, Newsession Ticket (4):
* old SSL session ID is stale, removing
* Connection #0 to host www.example.com left intact
Any help would be appriciated!!
Thanks

Answer 1

I suggest you to refer to the code in this issue:
ASN1_TIME *expires = X509_get_notAfter(cert.get());
// Construct another ASN1_TIME for the unix epoch, get the difference
// between them and use that to calculate a unix timestamp representing
// when the cert expires
ASN1_TIME_ptr epoch(ASN1_TIME_new(), ASN1_STRING_free);
ASN1_TIME_set_string(epoch.get(), "700101000000");
int days, seconds;
ASN1_TIME_diff(&days, &seconds, epoch.get(), expires);
time_t expire_timestamp = (days * 24 * 60 * 60) + seconds;
std::cout << "Expiration timestamp:" << std::endl;
std::cout << expire_timestamp << std::endl;
std::cout << std::endl;