--- title: "HTTPS Client" order: 6 --- In the previous chapter, you set up OpenSSL. Now let's put it to use with an HTTPS client. You can use the same `httplib::Client` from Chapter 2. Just pass a URL with the `https://` scheme to the constructor. ## GET Request Let's try accessing a real HTTPS site. ```cpp #define CPPHTTPLIB_OPENSSL_SUPPORT #include "httplib.h" #include int main() { httplib::Client cli("https://nghttp2.org"); auto res = cli.Get("/"); if (res) { std::cout << res->status << std::endl; // 200 std::cout << res->body.substr(0, 100) << std::endl; // First 100 chars of the HTML } else { std::cout << "Error: " << httplib::to_string(res.error()) << std::endl; } } ``` In Chapter 2, you wrote `httplib::Client cli("http://localhost:8080")`. All you need to change is the scheme to `https://`. Every API you learned in Chapter 2 -- `Get()`, `Post()`, and so on -- works exactly the same way. ```sh curl https://nghttp2.org/ ``` ## Specifying a Port The default port for HTTPS is 443. If you need a different port, include it in the URL. ```cpp httplib::Client cli("https://localhost:8443"); ``` ## CA Certificate Verification When connecting over HTTPS, `httplib::Client` verifies the server certificate by default. It only connects to servers whose certificate was issued by a trusted CA (Certificate Authority). CA certificates are loaded automatically from the Keychain on macOS, the system CA certificate store on Linux, and the Windows certificate store on Windows. In most cases, no extra configuration is needed. ### Specifying a CA Certificate File On some environments, the system CA certificates may not be found. In that case, use `set_ca_cert_path()` to specify the path directly. ```cpp httplib::Client cli("https://nghttp2.org"); cli.set_ca_cert_path("/etc/ssl/certs/ca-certificates.crt"); auto res = cli.Get("/"); ``` ```sh curl --cacert /etc/ssl/certs/ca-certificates.crt https://nghttp2.org/ ``` ### Disabling Certificate Verification During development, you might want to connect to a server with a self-signed certificate. You can disable verification for that. ```cpp httplib::Client cli("https://localhost:8443"); cli.enable_server_certificate_verification(false); auto res = cli.Get("/"); ``` ```sh curl -k https://localhost:8443/ ``` Never disable this in production. It opens you up to man-in-the-middle attacks. ## Following Redirects When accessing HTTPS sites, you'll often encounter redirects. For example, `http://` to `https://`, or a bare domain to `www`. By default, redirects are not followed. You can check the redirect target in the `Location` header. ```cpp httplib::Client cli("https://nghttp2.org"); auto res = cli.Get("/httpbin/redirect/3"); if (res) { std::cout << res->status << std::endl; // 302 std::cout << res->get_header_value("Location") << std::endl; } ``` ```sh curl https://nghttp2.org/httpbin/redirect/3 ``` Call `set_follow_location(true)` to automatically follow redirects and get the final response. ```cpp httplib::Client cli("https://nghttp2.org"); cli.set_follow_location(true); auto res = cli.Get("/httpbin/redirect/3"); if (res) { std::cout << res->status << std::endl; // 200 (the final response) } ``` ```sh curl -L https://nghttp2.org/httpbin/redirect/3 ``` ## Next Steps Now you know how to use the HTTPS client. Next, let's set up your own HTTPS server. We'll start with creating a self-signed certificate. **Next:** [HTTPS Server](../07-https-server)