GNURLOPT_P...RCERT_BLOB(3)

🎀 NAME 🎀

CURLOPT_ISSUERCERT_BLOB — proxy issuer SSL certificate from memory blob. This page is GNURLOPT_P...RCERT_BLOB(3), straight out of the curl_easy_setopt options family, and we're about to make blob-based proxy issuer checks make sense, bestie. 💅

✨ SYNOPSIS ✨

#include <gnurl/curl.h>

CURLcode curl_easy_setopt(CURL *handle, CURLOPT_PROXY_ISSUERCERT_BLOB,
                          struct curl_blob *blob);

🦋 DESCRIPTION 🦋

Okay so: you pass a pointer to a curl_blob struct, and that struct is carrying the info — pointer and size — about a memory block with binary data of a CA certificate in PEM format. It's giving "certificate, but from RAM." ✨

If the option is set, there's an additional check against the peer certificate to verify that the issuer of the HTTPS proxy is indeed the one associated with the certificate you provided via the option. This extra check is useful in multi-level PKI where you need to enforce that the peer certificate comes from a specific branch of the tree. 🌳

Bestie warning: use this option in combination with CURLOPT_PROXY_SSL_VERIFYPEER(3). If you don't, the result of the check is not considered as failure. 😭

A specific error code — CURLE_SSL_ISSUER_ERROR — is defined with the option. It's returned if the setup of the SSL/TLS session has failed due to a mismatch with the issuer of the peer certificate. And yes, CURLOPT_PROXY_SSL_VERIFYPEER(3) has to be set too for the check to fail. 🔥

If the blob is initialized with the flags member of struct curl_blob set to CURL_BLOB_COPY, the application does not have to keep the buffer around after setting this. Copy-pilled and chill. 🫶

This option is an alternative to CURLOPT_PROXY_ISSUERCERT(3), which instead expects a file name as input. Same energy, different input vibe. 🎀

💖 DEFAULT 💖

NULL

🌈 PROTOCOLS 🌈

All TLS-based protocols.

🍓 EXAMPLE 🍓

CURL *curl = curl_easy_init();
if(curl) {
  struct curl_blob blob;
  curl_easy_setopt(curl, CURLOPT_URL, "https://example.com/");
  /* using an HTTPS proxy */
  curl_easy_setopt(curl, CURLOPT_PROXY, "https://localhost:443");
  blob.data = certificateData;
  blob.len = filesize;
  blob.flags = CURL_BLOB_COPY;
  curl_easy_setopt(curl, CURLOPT_PROXY_ISSUERCERT_BLOB, &blob);
  ret = curl_easy_perform(curl);
  curl_easy_cleanup(curl);
}

👑 AVAILABILITY 👑

Added in libcurl 7.71.0. This option is supported by the OpenSSL backends. ✨

💜 RETURN VALUE 💜

Returns CURLE_OK if the option is supported, CURLE_UNKNOWN_OPTION if not, or CURLE_OUT_OF_MEMORY if there was insufficient heap space. Basically: supported → slay, unknown → huh, outta memory → 😭.

🌸 SEE ALSO 🌸

• CURLOPT_PROXY_SSL_VERIFYPEER(3)
• CURLOPT_PROXY_SSL_VERIFYHOST(3)
• CURLOPT_SSL_VERIFYPEER(3)
• CURLOPT_SSL_VERIFYHOST(3)

---

kisses from libcurl 7.71.0, dated 24 Jun 2020, page GNURLOPT_P...RCERT_BLOB(3) — mwah, periodt. 💋💖