[nginx] SSL: support for per-certificate chains.

[Maxim Dounin]

details:   http://hg.nginx.org/nginx/rev/d3302eb87a0c
branches:  
changeset: 6549:d3302eb87a0c
user:      Maxim Dounin <mdounin at mdounin.ru>
date:      Thu May 19 14:46:32 2016 +0300
description:
SSL: support for per-certificate chains.

The SSL_CTX_add0_chain_cert() function as introduced in OpenSSL 1.0.2 now
used instead of SSL_CTX_add_extra_chain_cert().

SSL_CTX_add_extra_chain_cert() adds extra certs for all certificates
in the context, while SSL_CTX_add0_chain_cert() only to a particular
certificate.  There is no difference unless multiple certificates are used,
though it is important when using multiple certificates.

Additionally, SSL_CTX_select_current_cert() is now called before using
a chain to make sure correct chain will be returned.

diffstat:

 src/event/ngx_event_openssl.c          |  19 +++++++++++++++++++
 src/event/ngx_event_openssl_stapling.c |  16 ++++++++++++++--
 2 files changed, 33 insertions(+), 2 deletions(-)

diffs (69 lines):

diff --git a/src/event/ngx_event_openssl.c b/src/event/ngx_event_openssl.c
--- a/src/event/ngx_event_openssl.c
+++ b/src/event/ngx_event_openssl.c
@@ -408,6 +408,24 @@ ngx_ssl_certificate(ngx_conf_t *cf, ngx_
             return NGX_ERROR;
         }
 
+#ifdef SSL_CTRL_CHAIN_CERT
+
+        /*
+         * SSL_CTX_add0_chain_cert() is needed to add chain to
+         * a particular certificate when multiple certificates are used;
+         * only available in OpenSSL 1.0.2+
+         */
+
+        if (SSL_CTX_add0_chain_cert(ssl->ctx, x509) == 0) {
+            ngx_ssl_error(NGX_LOG_EMERG, ssl->log, 0,
+                          "SSL_CTX_add0_chain_cert(\"%s\") failed",
+                          cert->data);
+            X509_free(x509);
+            BIO_free(bio);
+            return NGX_ERROR;
+        }
+
+#else
         if (SSL_CTX_add_extra_chain_cert(ssl->ctx, x509) == 0) {
             ngx_ssl_error(NGX_LOG_EMERG, ssl->log, 0,
                           "SSL_CTX_add_extra_chain_cert(\"%s\") failed",
@@ -416,6 +434,7 @@ ngx_ssl_certificate(ngx_conf_t *cf, ngx_
             BIO_free(bio);
             return NGX_ERROR;
         }
+#endif
     }
 
     BIO_free(bio);
diff --git a/src/event/ngx_event_openssl_stapling.c b/src/event/ngx_event_openssl_stapling.c
--- a/src/event/ngx_event_openssl_stapling.c
+++ b/src/event/ngx_event_openssl_stapling.c
@@ -287,7 +287,13 @@ ngx_ssl_stapling_issuer(ngx_conf_t *cf, 
 
     cert = staple->cert;
 
-#if OPENSSL_VERSION_NUMBER >= 0x10001000L
+#ifdef SSL_CTRL_SELECT_CURRENT_CERT
+    /* OpenSSL 1.0.2+ */
+    SSL_CTX_select_current_cert(ssl->ctx, cert);
+#endif
+
+#ifdef SSL_CTRL_GET_EXTRA_CHAIN_CERTS
+    /* OpenSSL 1.0.1+ */
     SSL_CTX_get_extra_chain_certs(ssl->ctx, &chain);
 #else
     chain = ssl->ctx->extra_certs;
@@ -621,7 +627,13 @@ ngx_ssl_stapling_ocsp_handler(ngx_ssl_oc
         goto error;
     }
 
-#if OPENSSL_VERSION_NUMBER >= 0x10001000L
+#ifdef SSL_CTRL_SELECT_CURRENT_CERT
+    /* OpenSSL 1.0.2+ */
+    SSL_CTX_select_current_cert(staple->ssl_ctx, ctx->cert);
+#endif
+
+#ifdef SSL_CTRL_GET_EXTRA_CHAIN_CERTS
+    /* OpenSSL 1.0.1+ */
     SSL_CTX_get_extra_chain_certs(staple->ssl_ctx, &chain);
 #else
     chain = staple->ssl_ctx->extra_certs;