MEDIUM: ssl: implements 'default-crt' keyword for bind Lines

The 'default-crt' bind keyword allows to specify multiples
default/fallback certificates, allowing one to have an RSA as well as an
ECDSA default.

doc/configuration.txt

@@ -15474,11 +15474,12 @@ crt <cert>
   This means that when loading certificates from a directory, it is highly
   recommended to load the default one first as a file or to ensure that it will
   always be the first one in the directory. In order to chose multiple default
-  certificates (1 rsa and 1 ecdsa), there are 2 options:
+  certificates (1 rsa and 1 ecdsa), there are 3 options:
   - A multi-cert bundle can be configured as the first certificate
     (`crt foobar.pem` in the configuration where the existing files
     are `foobar.pem.ecdsa` and `foobar.pem.rsa`.
   - Or a '*' filter for each certificate in a crt-list line.
+  - The 'default-crt' keyword can be used.
 
   Note that the same cert may be loaded multiple times without side effects.
 
@@ -15585,6 +15586,23 @@ crt-list <file>
         default.pem.rsa *
         default.pem.ecdsa *
 
+default-crt <cert>
+  This option does the same as the "crt" option, with the difference that this
+  certificate will be used as a default one. It is possible to add multiple
+  default certificates to have an ECDSA and an RSA one, having more is not
+  really useful.
+
+  A default certificate is used when no "strict-sni" option is used on the bind
+  line. A default certificate is provided when the servername extension was not
+  used by the client, or when the servername does not match any configured
+  certificate.
+
+  Example:
+
+     bind *:443 default-crt foobar.pem.rsa default-crt foobar.pem.ecdsa crt website.pem.rsa
+
+  See also the "crt" keyword.
+
 defer-accept
   Is an optional keyword which is supported only on certain Linux kernels. It
   states that a connection will only be accepted once some data arrive on it,

include/haproxy/ssl_sock.h

@@ -123,7 +123,7 @@ void ssl_async_fd_free(int fd);
 #endif
 struct issuer_chain* ssl_get0_issuer_chain(X509 *cert);
 int ssl_load_global_issuer_from_BIO(BIO *in, char *fp, char **err);
-int ssl_sock_load_cert(char *path, struct bind_conf *bind_conf, char **err);
+int ssl_sock_load_cert(char *path, struct bind_conf *bind_conf, int is_default, char **err);
 int ssl_sock_load_srv_cert(char *path, struct server *server, int create_if_none, char **err);
 void ssl_free_global_issuers(void);
 int ssl_initialize_random(void);

src/cfgparse-ssl.c

@@ -777,6 +777,7 @@ static int bind_parse_ciphersuites(char **args, int cur_arg, struct proxy *px, s
 static int bind_parse_crt(char **args, int cur_arg, struct proxy *px, struct bind_conf *conf, char **err)
 {
 	char path[MAXPATHLEN];
+	int default_crt = *args[cur_arg] == 'd' ? 1 : 0;
 
 	if (!*args[cur_arg + 1]) {
 		memprintf(err, "'%s' : missing certificate location", args[cur_arg]);
@@ -789,10 +790,10 @@ static int bind_parse_crt(char **args, int cur_arg, struct proxy *px, struct bin
 			memprintf(err, "'%s' : path too long", args[cur_arg]);
 			return ERR_ALERT | ERR_FATAL;
 		}
-		return ssl_sock_load_cert(path, conf, err);
+		return ssl_sock_load_cert(path, conf, default_crt, err);
 	}
 
-	return ssl_sock_load_cert(args[cur_arg + 1], conf, err);
+	return ssl_sock_load_cert(args[cur_arg + 1], conf, default_crt, err);
 }
 
 /* parse the "crt-list" bind keyword. Returns a set of ERR_* flags possibly with an error in <err>. */
@@ -2240,6 +2241,7 @@ static struct bind_kw_list bind_kws = { "SSL", { }, {
 	{ "crt-ignore-err",        bind_parse_ignore_err,         1 }, /* set error IDs to ignore on verify depth == 0 */
 	{ "crt-list",              bind_parse_crt_list,           1 }, /* load a list of crt from this location */
 	{ "curves",                bind_parse_curves,             1 }, /* set SSL curve suite */
+	{ "default-crt",           bind_parse_crt,                1 }, /* load SSL certificates from this location */
 	{ "ecdhe",                 bind_parse_ecdhe,              1 }, /* defines named curve for elliptic curve Diffie-Hellman */
 	{ "force-sslv3",           bind_parse_tls_method_options, 0 }, /* force SSLv3 */
 	{ "force-tlsv10",          bind_parse_tls_method_options, 0 }, /* force TLSv10 */

src/ssl_sock.c

@@ -3760,19 +3760,20 @@ int ssl_sock_load_cert_list_file(char *file, int dir, struct bind_conf *bind_con
 }
 
 /* Returns a set of ERR_* flags possibly with an error in <err>. */
-int ssl_sock_load_cert(char *path, struct bind_conf *bind_conf, char **err)
+int ssl_sock_load_cert(char *path, struct bind_conf *bind_conf, int is_default, char **err)
 {
 	struct stat buf;
 	int cfgerr = 0;
 	struct ckch_store *ckchs;
 	struct ckch_inst *ckch_inst = NULL;
 	int found = 0; /* did we found a file to load ? */
-	int is_default = 0;
 
 	/* if the SNI trees were empty the first "crt" become a default certificate,
 	 * it can be applied on multiple certificates if it's a bundle */
+	if (is_default == 0) {
 		if (eb_is_empty(&bind_conf->sni_ctx) && eb_is_empty(&bind_conf->sni_w_ctx))
 			is_default = 1;
+	}
 
 	if ((ckchs = ckchs_lookup(path))) {
 		/* we found the ckchs in the tree, we can use it directly */