New ctrl to set current certificate.

New ctrl sets current certificate based on certain criteria. Currently
two options: set the first valid certificate as current and set the
next valid certificate as current. Using these an application can
iterate over all certificates in an SSL_CTX or SSL structure.
(cherry picked from commit 0f78819c8c)

demos/bio/server-arg.c

@@ -82,7 +82,24 @@ int main(int argc, char *argv[])
 		ERR_print_errors_fp(stderr);
 		goto err;
 		}
-
+#if 0
+	/* Demo of how to iterate over all certificates in an SSL_CTX
+	 * structure.
+	 */
+	{
+	X509 *x;
+	int rv;
+	rv = SSL_CTX_set_current_cert(ctx, SSL_CERT_SET_FIRST);
+	while (rv)
+		{
+		X509 *x = SSL_CTX_get0_certificate(ctx);
+		X509_NAME_print_ex_fp(stdout, X509_get_subject_name(x), 0, XN_FLAG_ONELINE);
+		printf("\n");
+		rv = SSL_CTX_set_current_cert(ctx, SSL_CERT_SET_NEXT);
+		}
+	fflush(stdout);
+	}
+#endif
 	/* Setup server side SSL bio */
 	ssl_bio=BIO_new_ssl(ctx,0);
 

doc/ssl/SSL_CTX_add1_chain_cert.pod

@@ -7,7 +7,8 @@ SSL_CTX_add1_chain_cert, SSL_CTX_get0_chain_certs, SSL_CTX_clear_chain_certs,
 SSL_set0_chain, SSL_set1_chain, SSL_add0_chain_cert, SSL_add1_chain_cert,
 SSL_get0_chain_certs, SSL_clear_chain_certs, SSL_CTX_build_cert_chain,
 SSL_build_cert_chain, SSL_CTX_select_current_cert,
-SSL_select_current_cert - extra chain certificate processing
+SSL_select_current_cert, SSL_CTX_set_current_cert, SSL_set_current_cert - extra
+chain certificate processing
 
 =head1 SYNOPSIS
 
@@ -32,6 +33,8 @@ SSL_select_current_cert - extra chain certificate processing
 
  int SSL_CTX_select_current_cert(SSL_CTX *ctx, X509 *x509);
  int SSL_select_current_cert(SSL *ssl, X509 *x509);
+ int SSL_CTX_set_current_cert(SSL_CTX *ctx, long op);
+ int SSL_set_current_cert(SSL *ssl, long op);
 
 =head1 DESCRIPTION
 
@@ -65,8 +68,14 @@ function such as SSL_CTX_use_certificate().
 
 SSL_set0_chain(), SSL_set1_chain(), SSL_add0_chain_cert(),
 SSL_add1_chain_cert(), SSL_get0_chain_certs(), SSL_clear_chain_certs(),
-SSL_build_cert_chain() and SSL_select_current_cert() are similar except they
-apply to SSL structure B<ssl>.
+SSL_build_cert_chain(), SSL_select_current_cert() and SSL_set_current_cert()
+are similar except they apply to SSL structure B<ssl>.
+
+SSL_CTX_set_current_cert() changes the current certificate to a value based
+on the B<op> argument. Currently B<op> can be B<SSL_CERT_SET_FIRST> to use
+the first valid certificate or B<SSL_CERT_SET_NEXT> to set the next valid
+certificate after the current certificate. These two operations can be
+used to iterate over all certificates in an B<SSL_CTX> structure.
 
 All these functions are implemented as macros. Those containing a B<1>
 increment the reference count of the supplied certificate or chain so it must

ssl/s3_lib.c

@@ -3438,6 +3438,9 @@ long ssl3_ctrl(SSL *s, int cmd, long larg, void *parg)
 	case SSL_CTRL_SELECT_CURRENT_CERT:
 		return ssl_cert_select_current(s->cert, (X509 *)parg);
 
+	case SSL_CTRL_SET_CURRENT_CERT:
+		return ssl_cert_set_current(s->cert, larg);
+
 #ifndef OPENSSL_NO_EC
 	case SSL_CTRL_GET_CURVES:
 		{
@@ -3943,6 +3946,9 @@ long ssl3_ctx_ctrl(SSL_CTX *ctx, int cmd, long larg, void *parg)
 	case SSL_CTRL_SELECT_CURRENT_CERT:
 		return ssl_cert_select_current(ctx->cert, (X509 *)parg);
 
+	case SSL_CTRL_SET_CURRENT_CERT:
+		return ssl_cert_set_current(ctx->cert, larg);
+
 	default:
 		return(0);
 		}

ssl/ssl.h

@@ -1870,6 +1870,10 @@ DECLARE_PEM_rw(SSL_SESSION, SSL_SESSION)
 
 #define SSL_CTRL_GET_CHAIN_CERTS		115
 #define SSL_CTRL_SELECT_CURRENT_CERT		116
+#define SSL_CTRL_SET_CURRENT_CERT		117
+
+#define SSL_CERT_SET_FIRST			1
+#define SSL_CERT_SET_NEXT			2
 
 #define DTLSv1_get_timeout(ssl, arg) \
 	SSL_ctrl(ssl,DTLS_CTRL_GET_TIMEOUT,0, (void *)arg)
@@ -1929,6 +1933,9 @@ DECLARE_PEM_rw(SSL_SESSION, SSL_SESSION)
 #define SSL_CTX_select_current_cert(ctx,x509) \
 	SSL_CTX_ctrl(ctx,SSL_CTRL_SELECT_CURRENT_CERT,0,(char *)x509)
 
+#define SSL_CTX_set_current_cert(ctx, op) \
+	SSL_CTX_ctrl(ctx,SSL_CTRL_SET_CURRENT_CERT, op, NULL)
+
 #define SSL_CTX_set0_verify_cert_store(ctx,st) \
 	SSL_CTX_ctrl(ctx,SSL_CTRL_SET_VERIFY_CERT_STORE,0,(char *)st)
 #define SSL_CTX_set1_verify_cert_store(ctx,st) \
@@ -1954,6 +1961,8 @@ DECLARE_PEM_rw(SSL_SESSION, SSL_SESSION)
 	SSL_ctrl(s,SSL_CTRL_BUILD_CERT_CHAIN, flags, NULL)
 #define SSL_select_current_cert(ctx,x509) \
 	SSL_ctrl(ctx,SSL_CTRL_SELECT_CURRENT_CERT,0,(char *)x509)
+#define SSL_set_current_cert(ctx,op) \
+	SSL_ctrl(ctx,SSL_CTRL_SET_CURRENT_CERT, op, NULL)
 
 #define SSL_set0_verify_cert_store(s,st) \
 	SSL_ctrl(s,SSL_CTRL_SET_VERIFY_CERT_STORE,0,(char *)st)

ssl/ssl_cert.c

@@ -646,6 +646,32 @@ int ssl_cert_select_current(CERT *c, X509 *x)
 	return 0;
 	}
 
+int ssl_cert_set_current(CERT *c, long op)
+	{
+	int i, idx;
+	if (!c)
+		return 0;
+	if (op == SSL_CERT_SET_FIRST)
+		idx = 0;
+	else if (op == SSL_CERT_SET_NEXT)
+		{
+		idx = (int)(c->key - c->pkeys + 1);
+		if (idx >= SSL_PKEY_NUM)
+			return 0;
+		}
+	else
+		return 0;
+	for (i = idx; i < SSL_PKEY_NUM; i++)
+		{
+		if (c->pkeys[i].x509)
+			{
+			c->key = &c->pkeys[i];
+			return 1;
+			}
+		}
+	return 0;
+	}
+
 void ssl_cert_set_cert_cb(CERT *c, int (*cb)(SSL *ssl, void *arg), void *arg)
 	{
 	c->cert_cb = cb;

ssl/ssl_locl.h

@@ -1001,6 +1001,8 @@ int ssl_cert_set1_chain(CERT *c, STACK_OF(X509) *chain);
 int ssl_cert_add0_chain_cert(CERT *c, X509 *x);
 int ssl_cert_add1_chain_cert(CERT *c, X509 *x);
 int ssl_cert_select_current(CERT *c, X509 *x);
+int ssl_cert_set_current(CERT *c, long arg);
+X509 *ssl_cert_get0_next_certificate(CERT *c, int first);
 void ssl_cert_set_cert_cb(CERT *c, int (*cb)(SSL *ssl, void *arg), void *arg);
 
 int ssl_verify_cert_chain(SSL *s,STACK_OF(X509) *sk);