CURLOPT_SSL_CTX_*.3: tidy up the example

Use the proper code style. Don't store return codes that aren't read.
Copy the same example into CURLOPT_SSL_CTX_FUNCTION.3 as well.

Closes #7500

2 files changed, 92 insertions, 18 deletions

diff --git a/docs/libcurl/opts/CURLOPT_SSL_CTX_DATA.3 b/docs/libcurl/opts/CURLOPT_SSL_CTX_DATA.3
index 1f4b44544..5af094553 100644
--- a/docs/libcurl/opts/CURLOPT_SSL_CTX_DATA.3
+++ b/docs/libcurl/opts/CURLOPT_SSL_CTX_DATA.3
@@ -5,7 +5,7 @@
 .\" *                            | (__| |_| |  _ <| |___
 .\" *                             \___|\___/|_| \_\_____|
 .\" *
-.\" * Copyright (C) 1998 - 2019, Daniel Stenberg, <daniel@haxx.se>, et al.
+.\" * Copyright (C) 1998 - 2021, Daniel Stenberg, <daniel@haxx.se>, et al.
 .\" *
 .\" * This software is licensed as described in the file COPYING, which
 .\" * you should have received as part of this distribution. The terms
@@ -46,11 +46,11 @@ All TLS based protocols: HTTPS, FTPS, IMAPS, POP3S, SMTPS etc.
 static CURLcode sslctx_function(CURL *curl, void *sslctx, void *parm)
 {
   X509_STORE *store;
-  X509 *cert=NULL;
+  X509 *cert = NULL;
   BIO *bio;
-  char *mypem = (char *)parm;
+  char *mypem = parm;
   /* get a BIO */
-  bio=BIO_new_mem_buf(mypem, -1);
+  bio = BIO_new_mem_buf(mypem, -1);
   /* use it to read the PEM formatted certificate from memory into an
    * X509 structure that SSL can use
    */
@@ -59,10 +59,10 @@ static CURLcode sslctx_function(CURL *curl, void *sslctx, void *parm)
     printf("PEM_read_bio_X509 failed...\\n");
 
   /* get a pointer to the X509 certificate store (which may be empty) */
-  store=SSL_CTX_get_cert_store((SSL_CTX *)sslctx);
+  store = SSL_CTX_get_cert_store((SSL_CTX *)sslctx);
 
   /* add our certificate to this store */
-  if(X509_STORE_add_cert(store, cert)==0)
+  if(X509_STORE_add_cert(store, cert) == 0)
     printf("error adding certificate\\n");
 
   /* decrease reference counts */
@@ -88,20 +88,21 @@ int main(void)
     "omTxJBzcoTWcFbLUvFUufQb1nA5V9FrWk9p2rSVzTMVD\\n"
     "-----END CERTIFICATE-----\\n";
 
-  rv=curl_global_init(CURL_GLOBAL_ALL);
-  ch=curl_easy_init();
-  rv=curl_easy_setopt(ch, CURLOPT_SSLCERTTYPE, "PEM");
-  rv=curl_easy_setopt(ch, CURLOPT_SSL_VERIFYPEER, 1L);
-  rv=curl_easy_setopt(ch, CURLOPT_URL, "https://www.example.com/");
+  curl_global_init(CURL_GLOBAL_ALL);
+  ch = curl_easy_init();
+
+  curl_easy_setopt(ch, CURLOPT_SSLCERTTYPE, "PEM");
+  curl_easy_setopt(ch, CURLOPT_SSL_VERIFYPEER, 1L);
+  curl_easy_setopt(ch, CURLOPT_URL, "https://www.example.com/");
 
   /* Retrieve page using cacerts' certificate -> will succeed
    * load the certificate by installing a function doing the necessary
    * "modifications" to the SSL CONTEXT just before link init
    */
-  rv=curl_easy_setopt(ch, CURLOPT_SSL_CTX_FUNCTION, *sslctx_function);
-  rv=curl_easy_setopt(ch, CURLOPT_SSL_CTX_DATA, mypem);
-  rv=curl_easy_perform(ch);
-  if(rv==CURLE_OK)
+  curl_easy_setopt(ch, CURLOPT_SSL_CTX_FUNCTION, *sslctx_function);
+  curl_easy_setopt(ch, CURLOPT_SSL_CTX_DATA, mypem);
+  rv = curl_easy_perform(ch);
+  if(!rv)
     printf("*** transfer succeeded ***\\n");
   else
     printf("*** transfer failed ***\\n");
diff --git a/docs/libcurl/opts/CURLOPT_SSL_CTX_FUNCTION.3 b/docs/libcurl/opts/CURLOPT_SSL_CTX_FUNCTION.3
index afc299b08..5a1353395 100644
--- a/docs/libcurl/opts/CURLOPT_SSL_CTX_FUNCTION.3
+++ b/docs/libcurl/opts/CURLOPT_SSL_CTX_FUNCTION.3
@@ -5,7 +5,7 @@
 .\" *                            | (__| |_| |  _ <| |___
 .\" *                             \___|\___/|_| \_\_____|
 .\" *
-.\" * Copyright (C) 1998 - 2019, Daniel Stenberg, <daniel@haxx.se>, et al.
+.\" * Copyright (C) 1998 - 2021, Daniel Stenberg, <daniel@haxx.se>, et al.
 .\" *
 .\" * This software is licensed as described in the file COPYING, which
 .\" * you should have received as part of this distribution. The terms
@@ -75,9 +75,82 @@ NULL
 .SH PROTOCOLS
 All TLS based protocols: HTTPS, FTPS, IMAPS, POP3S, SMTPS etc.
 .SH EXAMPLE
-See cacertinmem.c in docs/examples directory for usage example.
+.nf
+/* OpenSSL specific */
+
+#include <openssl/ssl.h>
+#include <curl/curl.h>
+#include <stdio.h>
+
+static CURLcode sslctx_function(CURL *curl, void *sslctx, void *parm)
+{
+  X509_STORE *store;
+  X509 *cert = NULL;
+  BIO *bio;
+  char *mypem = parm;
+  /* get a BIO */
+  bio = BIO_new_mem_buf(mypem, -1);
+  /* use it to read the PEM formatted certificate from memory into an
+   * X509 structure that SSL can use
+   */
+  PEM_read_bio_X509(bio, &cert, 0, NULL);
+  if(cert == NULL)
+    printf("PEM_read_bio_X509 failed...\\n");
+
+  /* get a pointer to the X509 certificate store (which may be empty) */
+  store = SSL_CTX_get_cert_store((SSL_CTX *)sslctx);
+
+  /* add our certificate to this store */
+  if(X509_STORE_add_cert(store, cert) == 0)
+    printf("error adding certificate\\n");
+
+  /* decrease reference counts */
+  X509_free(cert);
+  BIO_free(bio);
+
+  /* all set to go */
+  return CURLE_OK;
+}
+
+int main(void)
+{
+  CURL * ch;
+  CURLcode rv;
+  char *mypem = /* example CA cert PEM - shortened */
+    "-----BEGIN CERTIFICATE-----\\n"
+    "MIIHPTCCBSWgAwIBAgIBADANBgkqhkiG9w0BAQQFADB5MRAwDgYDVQQKEwdSb290\\n"
+    "IENBMR4wHAYDVQQLExVodHRwOi8vd3d3LmNhY2VydC5vcmcxIjAgBgNVBAMTGUNB\\n"
+    "IENlcnQgU2lnbmluZyBBdXRob3JpdHkxITAfBgkqhkiG9w0BCQEWEnN1cHBvcnRA\\n"
+    "Y2FjZXJ0Lm9yZzAeFw0wMzAzMzAxMjI5NDlaFw0zMzAzMjkxMjI5NDlaMHkxEDAO\\n"
+    "GCSNe9FINSkYQKyTYOGWhlC0elnYjyELn8+CkcY7v2vcB5G5l1YjqrZslMZIBjzk\\n"
+    "zk6q5PYvCdxTby78dOs6Y5nCpqyJvKeyRKANihDjbPIky/qbn3BHLt4Ui9SyIAmW\\n"
+    "omTxJBzcoTWcFbLUvFUufQb1nA5V9FrWk9p2rSVzTMVD\\n"
+    "-----END CERTIFICATE-----\\n";
+
+  curl_global_init(CURL_GLOBAL_ALL);
+  ch = curl_easy_init();
+
+  curl_easy_setopt(ch, CURLOPT_SSLCERTTYPE, "PEM");
+  curl_easy_setopt(ch, CURLOPT_SSL_VERIFYPEER, 1L);
+  curl_easy_setopt(ch, CURLOPT_URL, "https://www.example.com/");
+
+  /* Retrieve page using cacerts' certificate -> will succeed
+   * load the certificate by installing a function doing the necessary
+   * "modifications" to the SSL CONTEXT just before link init
+   */
+  curl_easy_setopt(ch, CURLOPT_SSL_CTX_FUNCTION, *sslctx_function);
+  curl_easy_setopt(ch, CURLOPT_SSL_CTX_DATA, mypem);
+  rv = curl_easy_perform(ch);
+  if(!rv)
+    printf("*** transfer succeeded ***\\n");
+  else
+    printf("*** transfer failed ***\\n");
 
-https://curl.se/libcurl/c/cacertinmem.html
+  curl_easy_cleanup(ch);
+  curl_global_cleanup();
+  return rv;
+}
+.fi
 .SH AVAILABILITY
 Added in 7.11.0 for OpenSSL, in 7.42.0 for wolfSSL and in 7.54.0 for
 mbedTLS. Other SSL backends are not supported.