Add support for compressed certificates (RFC8879)

[openssl.git] / ssl / statem / extensions.c

diff --git a/ssl/statem/extensions.c b/ssl/statem/extensions.c
index 880189d9989fef8c6f6b68ceab94baff9001dd65..2cfc9f2b7ded651d68d8a0e08f9f37410821df42 100644 (file)
--- a/ssl/statem/extensions.c
+++ b/ssl/statem/extensions.c
@@ -62,6 +62,13 @@ static int final_maxfragmentlen(SSL_CONNECTION *s, unsigned int context,
                                 int sent);
 static int init_post_handshake_auth(SSL_CONNECTION *s, unsigned int context);
 static int final_psk(SSL_CONNECTION *s, unsigned int context, int sent);
+static int tls_init_compress_certificate(SSL_CONNECTION *sc, unsigned int context);
+static EXT_RETURN tls_construct_compress_certificate(SSL_CONNECTION *sc, WPACKET *pkt,
+                                                     unsigned int context,
+                                                     X509 *x, size_t chainidx);
+static int tls_parse_compress_certificate(SSL_CONNECTION *sc, PACKET *pkt,
+                                          unsigned int context,
+                                          X509 *x, size_t chainidx);
 
 /* Structure to define a built-in extension */
 typedef struct extensions_definition_st {
@@ -358,6 +365,15 @@ static const EXTENSION_DEFINITION ext_defs[] = {
         | SSL_EXT_TLS1_2_AND_BELOW_ONLY,
         NULL, NULL, NULL, tls_construct_stoc_cryptopro_bug, NULL, NULL
     },
+    {
+        TLSEXT_TYPE_compress_certificate,
+        SSL_EXT_CLIENT_HELLO | SSL_EXT_TLS1_3_CERTIFICATE_REQUEST
+        | SSL_EXT_TLS_IMPLEMENTATION_ONLY | SSL_EXT_TLS1_3_ONLY,
+        tls_init_compress_certificate,
+        tls_parse_compress_certificate, tls_parse_compress_certificate,
+        tls_construct_compress_certificate, tls_construct_compress_certificate,
+        NULL
+    },
     {
         TLSEXT_TYPE_early_data,
         SSL_EXT_CLIENT_HELLO | SSL_EXT_TLS1_3_ENCRYPTED_EXTENSIONS
@@ -1746,3 +1762,112 @@ static int final_psk(SSL_CONNECTION *s, unsigned int context, int sent)
 
     return 1;
 }
+
+static int tls_init_compress_certificate(SSL_CONNECTION *sc, unsigned int context)
+{
+    memset(sc->ext.compress_certificate_from_peer, 0,
+           sizeof(sc->ext.compress_certificate_from_peer));
+    return 1;
+}
+
+/* The order these are put into the packet imply a preference order: [brotli, zlib, zstd] */
+static EXT_RETURN tls_construct_compress_certificate(SSL_CONNECTION *sc, WPACKET *pkt,
+                                                     unsigned int context,
+                                                     X509 *x, size_t chainidx)
+{
+#ifndef OPENSSL_NO_COMP_ALG
+    int i;
+
+    if (!ossl_comp_has_alg(0))
+        return EXT_RETURN_NOT_SENT;
+
+    /* Do not indicate we support receiving compressed certificates */
+    if ((sc->options & SSL_OP_NO_RX_CERTIFICATE_COMPRESSION) != 0)
+        return EXT_RETURN_NOT_SENT;
+
+    if (sc->cert_comp_prefs[0] == TLSEXT_comp_cert_none)
+        return EXT_RETURN_NOT_SENT;
+
+    if (!WPACKET_put_bytes_u16(pkt, TLSEXT_TYPE_compress_certificate)
+            || !WPACKET_start_sub_packet_u16(pkt)
+            || !WPACKET_start_sub_packet_u8(pkt))
+        goto err;
+
+    for (i = 0; sc->cert_comp_prefs[i] != TLSEXT_comp_cert_none; i++) {
+        if (!WPACKET_put_bytes_u16(pkt, sc->cert_comp_prefs[i]))
+            goto err;
+    }
+    if (!WPACKET_close(pkt) || !WPACKET_close(pkt))
+        goto err;
+
+    sc->ext.compress_certificate_sent = 1;
+    return EXT_RETURN_SENT;
+ err:
+    SSLfatal(sc, SSL_AD_INTERNAL_ERROR, ERR_R_INTERNAL_ERROR);
+    return EXT_RETURN_FAIL;
+#else
+    return EXT_RETURN_NOT_SENT;
+#endif
+}
+
+#ifndef OPENSSL_NO_COMP_ALG
+static int tls_comp_in_pref(SSL_CONNECTION *sc, int alg)
+{
+    int i;
+
+    /* ossl_comp_has_alg() considers 0 as "any" */
+    if (alg == 0)
+        return 0;
+    /* Make sure algorithm is enabled */
+    if (!ossl_comp_has_alg(alg))
+        return 0;
+    /* If no preferences are set, it's ok */
+    if (sc->cert_comp_prefs[0] == TLSEXT_comp_cert_none)
+        return 1;
+    /* Find the algorithm */
+    for (i = 0; i < TLSEXT_comp_cert_limit; i++)
+        if (sc->cert_comp_prefs[i] == alg)
+            return 1;
+    return 0;
+}
+#endif
+
+int tls_parse_compress_certificate(SSL_CONNECTION *sc, PACKET *pkt, unsigned int context,
+                                   X509 *x, size_t chainidx)
+{
+#ifndef OPENSSL_NO_COMP_ALG
+    PACKET supported_comp_algs;
+    unsigned int comp;
+    int already_set[TLSEXT_comp_cert_limit];
+    int j = 0;
+
+    /* If no algorithms are available, ignore the extension */
+    if (!ossl_comp_has_alg(0))
+        return 1;
+
+    /* Ignore the extension and don't send compressed certificates */
+    if ((sc->options & SSL_OP_NO_TX_CERTIFICATE_COMPRESSION) != 0)
+        return 1;
+
+    if (!PACKET_as_length_prefixed_1(pkt, &supported_comp_algs)
+            || PACKET_remaining(&supported_comp_algs) == 0) {
+        SSLfatal(sc, SSL_AD_DECODE_ERROR, SSL_R_BAD_EXTENSION);
+        return 0;
+    }
+
+    memset(already_set, 0, sizeof(already_set));
+    /*
+     * The preference array has real values, so take a look at each
+     * value coming in, and make sure it's in our preference list
+     * The array is 0 (i.e. "none") terminated
+     * The preference list only contains supported algorithms
+     */
+    while (PACKET_get_1(&supported_comp_algs, &comp)) {
+        if (tls_comp_in_pref(sc, comp) && !already_set[comp]) {
+            sc->ext.compress_certificate_from_peer[j++] = comp;
+            already_set[comp] = 1;
+        }
+    }
+#endif
+    return 1;
+}