1---
2c: Copyright (C) Daniel Stenberg, <daniel@haxx.se>, et al.
3SPDX-License-Identifier: curl
4Title: CURLOPT_ISSUERCERT_BLOB
5Section: 3
6Source: libcurl
7See-also:
8  - CURLOPT_CRLFILE (3)
9  - CURLOPT_ISSUERCERT (3)
10  - CURLOPT_SSL_VERIFYHOST (3)
11  - CURLOPT_SSL_VERIFYPEER (3)
12Protocol:
13  - TLS
14TLS-backend:
15  - OpenSSL
16Added-in: 7.71.0
17---
18
19# NAME
20
21CURLOPT_ISSUERCERT_BLOB - issuer SSL certificate from memory blob
22
23# SYNOPSIS
24
25~~~c
26#include <curl/curl.h>
27
28CURLcode curl_easy_setopt(CURL *handle, CURLOPT_ISSUERCERT_BLOB,
29                          struct curl_blob *stblob);
30~~~
31
32# DESCRIPTION
33
34Pass a pointer to a curl_blob structure, which contains information (pointer
35and size) about a memory block with binary data of a CA certificate in PEM
36format. If the option is set, an additional check against the peer certificate
37is performed to verify the issuer is indeed the one associated with the
38certificate provided by the option. This additional check is useful in
39multi-level PKI where one needs to enforce that the peer certificate is from a
40specific branch of the tree.
41
42This option should be used in combination with the
43CURLOPT_SSL_VERIFYPEER(3) option. Otherwise, the result of the check is
44not considered as failure.
45
46A specific error code (CURLE_SSL_ISSUER_ERROR) is defined with the option,
47which is returned if the setup of the SSL/TLS session has failed due to a
48mismatch with the issuer of peer certificate (CURLOPT_SSL_VERIFYPEER(3)
49has to be set too for the check to fail).
50
51If the blob is initialized with the flags member of struct curl_blob set to
52CURL_BLOB_COPY, the application does not have to keep the buffer around after
53setting this.
54
55This option is an alternative to CURLOPT_ISSUERCERT(3) which instead
56expects a filename as input.
57
58# DEFAULT
59
60NULL
61
62# %PROTOCOLS%
63
64# EXAMPLE
65
66~~~c
67
68extern char *certificateData;
69extern size_t filesize;
70
71int main(void)
72{
73  CURL *curl = curl_easy_init();
74  if(curl) {
75    CURLcode res;
76    struct curl_blob blob;
77    curl_easy_setopt(curl, CURLOPT_URL, "https://example.com/");
78    blob.data = certificateData;
79    blob.len = filesize;
80    blob.flags = CURL_BLOB_COPY;
81    curl_easy_setopt(curl, CURLOPT_ISSUERCERT_BLOB, &blob);
82    res = curl_easy_perform(curl);
83    curl_easy_cleanup(curl);
84  }
85}
86~~~
87
88# %AVAILABILITY%
89
90# RETURN VALUE
91
92Returns CURLE_OK if the option is supported, CURLE_UNKNOWN_OPTION if not, or
93CURLE_OUT_OF_MEMORY if there was insufficient heap space.
94