SSL: RFC2253 compliant $ssl_client_s_dn and $ssl_client_i_dn.

Originally, the variables kept a result of X509_NAME_oneline(),
which is, according to the official documentation, a legacy
function.  It produces a non standard output form and has
various quirks and inconsistencies.

The RFC2253 compliant behavior is introduced for these variables.
The original variables are available through $ssl_client_s_dn_legacy
and $ssl_client_i_dn_legacy.

src/event/ngx_event_openssl.c

@@ -3437,6 +3437,109 @@ ngx_ssl_get_certificate(ngx_connection_t *c, ngx_pool_t *pool, ngx_str_t *s)
 
 ngx_int_t
 ngx_ssl_get_subject_dn(ngx_connection_t *c, ngx_pool_t *pool, ngx_str_t *s)
+{
+    BIO        *bio;
+    X509       *cert;
+    X509_NAME  *name;
+
+    s->len = 0;
+
+    cert = SSL_get_peer_certificate(c->ssl->connection);
+    if (cert == NULL) {
+        return NGX_OK;
+    }
+
+    name = X509_get_subject_name(cert);
+    if (name == NULL) {
+        return NGX_ERROR;
+    }
+
+    bio = BIO_new(BIO_s_mem());
+    if (bio == NULL) {
+        X509_free(cert);
+        return NGX_ERROR;
+    }
+
+    if (X509_NAME_print_ex(bio, name, 0, XN_FLAG_RFC2253) < 0) {
+        goto failed;
+    }
+
+    s->len = BIO_pending(bio);
+    s->data = ngx_pnalloc(pool, s->len);
+    if (s->data == NULL) {
+        goto failed;
+    }
+
+    BIO_read(bio, s->data, s->len);
+
+    BIO_free(bio);
+    X509_free(cert);
+
+    return NGX_OK;
+
+failed:
+
+    BIO_free(bio);
+    X509_free(cert);
+
+    return NGX_ERROR;
+}
+
+
+ngx_int_t
+ngx_ssl_get_issuer_dn(ngx_connection_t *c, ngx_pool_t *pool, ngx_str_t *s)
+{
+    BIO        *bio;
+    X509       *cert;
+    X509_NAME  *name;
+
+    s->len = 0;
+
+    cert = SSL_get_peer_certificate(c->ssl->connection);
+    if (cert == NULL) {
+        return NGX_OK;
+    }
+
+    name = X509_get_issuer_name(cert);
+    if (name == NULL) {
+        return NGX_ERROR;
+    }
+
+    bio = BIO_new(BIO_s_mem());
+    if (bio == NULL) {
+        X509_free(cert);
+        return NGX_ERROR;
+    }
+
+    if (X509_NAME_print_ex(bio, name, 0, XN_FLAG_RFC2253) < 0) {
+        goto failed;
+    }
+
+    s->len = BIO_pending(bio);
+    s->data = ngx_pnalloc(pool, s->len);
+    if (s->data == NULL) {
+        goto failed;
+    }
+
+    BIO_read(bio, s->data, s->len);
+
+    BIO_free(bio);
+    X509_free(cert);
+
+    return NGX_OK;
+
+failed:
+
+    BIO_free(bio);
+    X509_free(cert);
+
+    return NGX_ERROR;
+}
+
+
+ngx_int_t
+ngx_ssl_get_subject_dn_legacy(ngx_connection_t *c, ngx_pool_t *pool,
+    ngx_str_t *s)
 {
     char       *p;
     size_t      len;
@@ -3478,7 +3581,8 @@ ngx_ssl_get_subject_dn(ngx_connection_t *c, ngx_pool_t *pool, ngx_str_t *s)
 
 
 ngx_int_t
-ngx_ssl_get_issuer_dn(ngx_connection_t *c, ngx_pool_t *pool, ngx_str_t *s)
+ngx_ssl_get_issuer_dn_legacy(ngx_connection_t *c, ngx_pool_t *pool,
+    ngx_str_t *s)
 {
     char       *p;
     size_t      len;

src/event/ngx_event_openssl.h

@@ -205,6 +205,10 @@ ngx_int_t ngx_ssl_get_subject_dn(ngx_connection_t *c, ngx_pool_t *pool,
     ngx_str_t *s);
 ngx_int_t ngx_ssl_get_issuer_dn(ngx_connection_t *c, ngx_pool_t *pool,
     ngx_str_t *s);
+ngx_int_t ngx_ssl_get_subject_dn_legacy(ngx_connection_t *c, ngx_pool_t *pool,
+    ngx_str_t *s);
+ngx_int_t ngx_ssl_get_issuer_dn_legacy(ngx_connection_t *c, ngx_pool_t *pool,
+    ngx_str_t *s);
 ngx_int_t ngx_ssl_get_serial_number(ngx_connection_t *c, ngx_pool_t *pool,
     ngx_str_t *s);
 ngx_int_t ngx_ssl_get_fingerprint(ngx_connection_t *c, ngx_pool_t *pool,

src/http/modules/ngx_http_ssl_module.c

@@ -298,6 +298,12 @@ static ngx_http_variable_t  ngx_http_ssl_vars[] = {
     { ngx_string("ssl_client_i_dn"), NULL, ngx_http_ssl_variable,
       (uintptr_t) ngx_ssl_get_issuer_dn, NGX_HTTP_VAR_CHANGEABLE, 0 },
 
+    { ngx_string("ssl_client_s_dn_legacy"), NULL, ngx_http_ssl_variable,
+      (uintptr_t) ngx_ssl_get_subject_dn_legacy, NGX_HTTP_VAR_CHANGEABLE, 0 },
+
+    { ngx_string("ssl_client_i_dn_legacy"), NULL, ngx_http_ssl_variable,
+      (uintptr_t) ngx_ssl_get_issuer_dn_legacy, NGX_HTTP_VAR_CHANGEABLE, 0 },
+
     { ngx_string("ssl_client_serial"), NULL, ngx_http_ssl_variable,
       (uintptr_t) ngx_ssl_get_serial_number, NGX_HTTP_VAR_CHANGEABLE, 0 },