MINOR: quic: split transport params decoding/check

Function quic_transport_params_decode() is used for decoding received
parameters. Prior to this patch, it also contained validity checks on
some of the parameters. Finally, it also tested that mandatory
parameters were indeed found.

This patch separates this two parts. Params validity is now tested in a
new function quic_transport_params_check(), which can be called just
after decode operation.

This patch will be useful for QMux protocol, as this allows to reuse
decode operation without executing checks which are tied to the QUIC
specification, in particular for mandatory parameters.

diff --git a/src/quic_tp.c b/src/quic_tp.c
index ec2e9d5df6498adc6320f979ac6105ab6ff374b9..fd20d2c92793cbafc652a71c7b033585157f5721 100644 (file)
--- a/src/quic_tp.c
+++ b/src/quic_tp.c
@@ -267,17 +267,6 @@ quic_transport_param_decode(struct quic_transport_params *p, int server,
 
        switch (type) {
        case QUIC_TP_ORIGINAL_DESTINATION_CONNECTION_ID:
-               /* RFC 9000 18.2. Transport Parameter Definitions
-                *
-                * A client MUST NOT include any server-only transport parameter:
-                * original_destination_connection_id, preferred_address,
-                * retry_source_connection_id, or stateless_reset_token. A server MUST
-                * treat receipt of any of these transport parameters as a connection
-                * error of type TRANSPORT_PARAMETER_ERROR.
-                */
-               if (!server)
-                       return QUIC_TP_DEC_ERR_INVAL;
-
                if (len > sizeof p->original_destination_connection_id.data)
                        return QUIC_TP_DEC_ERR_TRUNC;
                if (len)
@@ -297,10 +286,6 @@ quic_transport_param_decode(struct quic_transport_params *p, int server,
                p->initial_source_connection_id_present = 1;
                break;
        case QUIC_TP_STATELESS_RESET_TOKEN:
-               /* see original_destination_connection_id RFC reference above. */
-               if (!server)
-                       return QUIC_TP_DEC_ERR_INVAL;
-
                if (len != sizeof p->stateless_reset_token)
                        return QUIC_TP_DEC_ERR_TRUNC;
                memcpy(p->stateless_reset_token, *buf, len);
@@ -308,10 +293,6 @@ quic_transport_param_decode(struct quic_transport_params *p, int server,
                p->with_stateless_reset_token = 1;
                break;
        case QUIC_TP_PREFERRED_ADDRESS:
-               /* see original_destination_connection_id RFC reference above. */
-               if (!server)
-                       return QUIC_TP_DEC_ERR_INVAL;
-
                if (!quic_transport_param_dec_pref_addr(&p->preferred_address, buf, *buf + len))
                        return QUIC_TP_DEC_ERR_TRUNC;
                p->with_preferred_address = 1;
@@ -324,15 +305,6 @@ quic_transport_param_decode(struct quic_transport_params *p, int server,
                if (!quic_dec_int(&p->max_udp_payload_size, buf, end))
                        return QUIC_TP_DEC_ERR_TRUNC;
 
-               /* RFC 9000 18.2. Transport Parameter Definitions
-                *
-                * max_udp_payload_size (0x03): [...]
-                * The default for this parameter is the maximum permitted UDP
-                * payload of 65527. Values below 1200 are invalid.
-                */
-               if (p->max_udp_payload_size < 1200)
-                       return QUIC_TP_DEC_ERR_INVAL;
-
                break;
        case QUIC_TP_INITIAL_MAX_DATA:
                if (!quic_dec_int(&p->initial_max_data, buf, end))
@@ -362,27 +334,11 @@ quic_transport_param_decode(struct quic_transport_params *p, int server,
                if (!quic_dec_int(&p->ack_delay_exponent, buf, end))
                        return QUIC_TP_DEC_ERR_TRUNC;
 
-               /* RFC 9000 18.2. Transport Parameter Definitions
-                *
-                * ack_delay_exponent (0x0a): [...]
-                * Values above 20 are invalid.
-                */
-               if (p->ack_delay_exponent > QUIC_TP_ACK_DELAY_EXPONENT_LIMIT)
-                       return QUIC_TP_DEC_ERR_INVAL;
-
                break;
        case QUIC_TP_MAX_ACK_DELAY:
                if (!quic_dec_int(&p->max_ack_delay, buf, end))
                        return QUIC_TP_DEC_ERR_TRUNC;
 
-               /* RFC 9000 18.2. Transport Parameter Definitions
-                *
-                * max_ack_delay (0x0b): [...]
-                * Values of 2^14 or greater are invalid.
-                */
-               if (p->max_ack_delay >= QUIC_TP_MAX_ACK_DELAY_LIMIT)
-                       return QUIC_TP_DEC_ERR_INVAL;
-
                break;
        case QUIC_TP_DISABLE_ACTIVE_MIGRATION:
                /* Zero-length parameter type. */
@@ -400,10 +356,6 @@ quic_transport_param_decode(struct quic_transport_params *p, int server,
                        return QUIC_TP_DEC_ERR_TRUNC;
                break;
        case QUIC_TP_RETRY_SOURCE_CONNECTION_ID:
-               /* see original_destination_connection_id RFC reference above. */
-               if (!server)
-                       return QUIC_TP_DEC_ERR_INVAL;
-
                if (len > sizeof p->retry_source_connection_id.data)
                        return QUIC_TP_DEC_ERR_TRUNC;
 
@@ -700,6 +652,18 @@ quic_transport_params_decode(struct quic_transport_params *p, int server,
                        return err;
        }
 
+       return QUIC_TP_DEC_ERR_NONE;
+}
+
+/* Check validity of decoded <p> transport parameters. The boolean argument
+ * <server> must be set according to the origin of the parameters.
+ *
+ * Returns 1 if params are valid, else 0 if TRANSPORT_PARAMETER_ERROR must be
+ * emitted.
+ */
+static enum quic_tp_dec_err
+quic_transport_params_check(const struct quic_transport_params *p, int server)
+{
        /* RFC 9000 7.3. Authenticating Connection IDs
         *
         * An endpoint MUST treat the absence of the
@@ -713,6 +677,45 @@ quic_transport_params_decode(struct quic_transport_params *p, int server,
                return QUIC_TP_DEC_ERR_INVAL;
        }
 
+       /* RFC 9000 18.2. Transport Parameter Definitions
+        *
+        * A client MUST NOT include any server-only transport parameter:
+        * original_destination_connection_id, preferred_address,
+        * retry_source_connection_id, or stateless_reset_token.
+        */
+       if (!server &&
+           (p->original_destination_connection_id_present ||
+            p->retry_source_connection_id.len ||
+            p->with_stateless_reset_token ||
+            p->with_preferred_address)) {
+               return QUIC_TP_DEC_ERR_INVAL;
+       }
+
+       /* RFC 9000 18.2. Transport Parameter Definitions
+        *
+        * max_udp_payload_size (0x03): [...]
+        * The default for this parameter is the maximum permitted UDP
+        * payload of 65527. Values below 1200 are invalid.
+        */
+       if (p->max_udp_payload_size < 1200)
+               return QUIC_TP_DEC_ERR_INVAL;
+
+       /* RFC 9000 18.2. Transport Parameter Definitions
+        *
+        * ack_delay_exponent (0x0a): [...]
+        * Values above 20 are invalid.
+        */
+       if (p->ack_delay_exponent > QUIC_TP_ACK_DELAY_EXPONENT_LIMIT)
+               return QUIC_TP_DEC_ERR_INVAL;
+
+       /* RFC 9000 18.2. Transport Parameter Definitions
+        *
+        * max_ack_delay (0x0b): [...]
+        * Values of 2^14 or greater are invalid.
+        */
+       if (p->max_ack_delay >= QUIC_TP_MAX_ACK_DELAY_LIMIT)
+               return QUIC_TP_DEC_ERR_INVAL;
+
        /* RFC 9000 18.2. Transport Parameter Definitions
         *
         * active_connection_id_limit (0x0e):
@@ -722,7 +725,7 @@ quic_transport_params_decode(struct quic_transport_params *p, int server,
         * connection with an error of type TRANSPORT_PARAMETER_ERROR.
         */
        if (p->active_connection_id_limit < QUIC_TP_DFLT_ACTIVE_CONNECTION_ID_LIMIT)
-               return QUIC_TP_DEC_ERR_INVAL;
+                return QUIC_TP_DEC_ERR_INVAL;
 
        return QUIC_TP_DEC_ERR_NONE;
 }
@@ -761,15 +764,17 @@ int quic_transport_params_store(struct quic_conn *qc, int server,
        quic_dflt_transport_params_cpy(tx_params);
 
        err = quic_transport_params_decode(tx_params, server, buf, end);
-       if (err == QUIC_TP_DEC_ERR_INVAL) {
+       if (err != QUIC_TP_DEC_ERR_NONE) {
+               TRACE_ERROR("error on transport parameters decoding", QUIC_EV_TRANSP_PARAMS, qc);
+               return 0;
+       }
+
+       err = quic_transport_params_check(tx_params, server);
+       if (err != QUIC_TP_DEC_ERR_NONE) {
                TRACE_ERROR("invalid transport parameter value", QUIC_EV_TRANSP_PARAMS, qc);
                quic_set_connection_close(qc, quic_err_transport(QC_ERR_TRANSPORT_PARAMETER_ERROR));
                return 1;
        }
-       else if (err == QUIC_TP_DEC_ERR_TRUNC) {
-               TRACE_ERROR("error on transport parameters decoding", QUIC_EV_TRANSP_PARAMS, qc);
-               return 0;
-       }
 
        if (edata_accepted && !qc_early_tranport_params_validate(qc, tx_params, &etps)) {
                TRACE_ERROR("could not validate early transport parameters", QUIC_EV_TRANSP_PARAMS, qc);