Tribblix: manual page: CURLOPT_ISSUERCERT

CURLOPT_ISSUERCERT_BLOB(3) Introduction to Library Functions

NAME

CURLOPT_ISSUERCERT_BLOB - issuer SSL certificate from memory blob

SYNOPSIS

#include <curl/curl.h>

CURLcode curl_easy_setopt(CURL *handle, CURLOPT_ISSUERCERT_BLOB,
struct curl_blob *stblob);

DESCRIPTION

Pass a pointer to a curl_blob structure, which contains information
(pointer and size) about a memory block with binary data of a CA
certificate in PEM format. If the option is set, an additional check
against the peer certificate is performed to verify the issuer is
indeed the one associated with the certificate provided by the
option. This additional check is useful in multi-level PKI where one
needs to enforce that the peer certificate is from a specific branch
of the tree.

This option should be used in combination with the
CURLOPT_SSL_VERIFYPEER(3) option. Otherwise, the result of the check
is not considered as failure.

A specific error code (CURLE_SSL_ISSUER_ERROR) is defined with the
option, which is returned if the setup of the SSL/TLS session has
failed due to a mismatch with the issuer of peer certificate
(CURLOPT_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.

This option is an alternative to CURLOPT_ISSUERCERT(3) which instead
expects a filename as input.

DEFAULT

NULL

PROTOCOLS

This functionality affects all TLS based protocols: HTTPS, FTPS,
IMAPS, POP3S, SMTPS etc.

This option works only with the following TLS backends: OpenSSL

EXAMPLE

extern char *certificateData;
extern size_t filesize;

int main(void)
{
CURL *curl = curl_easy_init();
if(curl) {
CURLcode res;
struct curl_blob blob;
curl_easy_setopt(curl, CURLOPT_URL, "https://example.com/");
blob.data = certificateData;
blob.len = filesize;
blob.flags = CURL_BLOB_COPY;
curl_easy_setopt(curl, CURLOPT_ISSUERCERT_BLOB, &blob);
res = curl_easy_perform(curl);
curl_easy_cleanup(curl);
}
}

AVAILABILITY

Added in curl 7.71.0

RETURN VALUE

curl_easy_setopt(3) returns a CURLcode indicating success or error.

CURLE_OK (0) means everything was OK, non-zero means an error
occurred, see libcurl-errors(3).