Add SSL_use_certificate_chain_file function

Add SSL_use_certiicate_chain file functions: this is works the same
way as SSL_CTX_use_certificate_chain_file but for an SSL structure.

Update SSL_CONF code to use the new function.
Update docs.
Update ordinals.

Reviewed-by: Rich Salz <rsalz@openssl.org>
diff --git a/ssl/ssl_rsa.c b/ssl/ssl_rsa.c
index 305b185..31ce9bd 100644
--- a/ssl/ssl_rsa.c
+++ b/ssl/ssl_rsa.c
@@ -641,7 +641,7 @@
  * followed by a sequence of CA certificates that should be sent to the peer
  * in the Certificate message.
  */
-int SSL_CTX_use_certificate_chain_file(SSL_CTX *ctx, const char *file)
+static int use_certificate_chain_file(SSL_CTX *ctx, SSL *ssl, const char *file)
 {
     BIO *in;
     int ret = 0;
@@ -652,23 +652,26 @@
 
     in = BIO_new(BIO_s_file_internal());
     if (in == NULL) {
-        SSLerr(SSL_F_SSL_CTX_USE_CERTIFICATE_CHAIN_FILE, ERR_R_BUF_LIB);
+        SSLerr(SSL_F_USE_CERTIFICATE_CHAIN_FILE, ERR_R_BUF_LIB);
         goto end;
     }
 
     if (BIO_read_filename(in, file) <= 0) {
-        SSLerr(SSL_F_SSL_CTX_USE_CERTIFICATE_CHAIN_FILE, ERR_R_SYS_LIB);
+        SSLerr(SSL_F_USE_CERTIFICATE_CHAIN_FILE, ERR_R_SYS_LIB);
         goto end;
     }
 
     x = PEM_read_bio_X509_AUX(in, NULL, ctx->default_passwd_callback,
                               ctx->default_passwd_callback_userdata);
     if (x == NULL) {
-        SSLerr(SSL_F_SSL_CTX_USE_CERTIFICATE_CHAIN_FILE, ERR_R_PEM_LIB);
+        SSLerr(SSL_F_USE_CERTIFICATE_CHAIN_FILE, ERR_R_PEM_LIB);
         goto end;
     }
 
-    ret = SSL_CTX_use_certificate(ctx, x);
+    if (ctx)
+        ret = SSL_CTX_use_certificate(ctx, x);
+    else
+        ret = SSL_use_certificate(ssl, x);
 
     if (ERR_peek_error() != 0)
         ret = 0;                /* Key/certificate mismatch doesn't imply
@@ -682,7 +685,12 @@
         int r;
         unsigned long err;
 
-        if (!SSL_CTX_clear_chain_certs(ctx)) {
+        if (ctx)
+            r = SSL_CTX_clear_chain_certs(ctx);
+        else
+            r = SSL_clear_chain_certs(ssl);
+
+        if (r == 0) {
             ret = 0;
             goto end;
         }
@@ -691,17 +699,20 @@
                                        ctx->default_passwd_callback,
                                        ctx->default_passwd_callback_userdata))
                != NULL) {
-            r = SSL_CTX_add0_chain_cert(ctx, ca);
+            if (ctx)
+                r = SSL_CTX_add0_chain_cert(ctx, ca);
+            else
+                r = SSL_add0_chain_cert(ssl, ca);
+            /*
+             * Note that we must not free ca if it was successfully added to
+             * the chain (while we must free the main certificate, since its
+             * reference count is increased by SSL_CTX_use_certificate).
+             */
             if (!r) {
                 X509_free(ca);
                 ret = 0;
                 goto end;
             }
-            /*
-             * Note that we must not free r if it was successfully added to
-             * the chain (while we must free the main certificate, since its
-             * reference count is increased by SSL_CTX_use_certificate).
-             */
         }
         /* When the while loop ends, it's usually just EOF. */
         err = ERR_peek_last_error();
@@ -717,6 +728,16 @@
     BIO_free(in);
     return (ret);
 }
+
+int SSL_CTX_use_certificate_chain_file(SSL_CTX *ctx, const char *file)
+{
+    return use_certificate_chain_file(ctx, NULL, file);
+}
+
+int SSL_use_certificate_chain_file(SSL *ssl, const char *file)
+{
+    return use_certificate_chain_file(NULL, ssl, file);
+}
 #endif
 
 #ifndef OPENSSL_NO_TLSEXT