dccp: Add packet type information to CCID-specific option parsing

This patch ...
 1. adds packet type information to ccid_hc_{rx,tx}_parse_options(). This is 
    necessary, since table 3 in RFC 4340, 5.8 leaves it to the CCIDs to state
    which options may (not) appear on what packet type.
 
 2. adds such a check for CCID-3's {Loss Event, Receive} Rate as specified in
    RFC 4340 8.3 ("Receive Rate options MUST NOT be sent on DCCP-Data packets")
    and 8.5 ("Loss Event Rate options MUST NOT be sent on DCCP-Data packets").

 3. removes an unused argument `idx' from ccid_hc_{rx,tx}_parse_options(). This
    is also no longer necessary, since the CCID-specific option-parsing routines
    are passed every single parameter of the type-length-value option encoding.

Also added documentation and made argument naming scheme consistent.

Signed-off-by: Gerrit Renker <gerrit@erg.abdn.ac.uk>

1 files changed, 8 insertions, 6 deletions

diff --git a/net/dccp/ccids/ccid3.c b/net/dccp/ccids/ccid3.c
index 12b601f11bfd..4c422fb2189f 100644
--- a/net/dccp/ccids/ccid3.c
+++ b/net/dccp/ccids/ccid3.c
@@ -483,9 +483,8 @@ done_computing_x:
                            jiffies + usecs_to_jiffies(t_nfb));
 }
 
-static int ccid3_hc_tx_parse_options(struct sock *sk, unsigned char option,
-                                     unsigned char len, u16 idx,
-                                     unsigned char *value)
+static int ccid3_hc_tx_parse_options(struct sock *sk, u8 packet_type,
+                                     u8 option, u8 *optval, u8 optlen)
 {
         struct ccid3_hc_tx_sock *hctx = ccid3_hc_tx_sk(sk);
         struct ccid3_options_received *opt_recv = &hctx->options_received;
@@ -494,12 +493,15 @@ static int ccid3_hc_tx_parse_options(struct sock *sk, unsigned char option,
         switch (option) {
         case TFRC_OPT_RECEIVE_RATE:
         case TFRC_OPT_LOSS_EVENT_RATE:
-                if (unlikely(len != 4)) {
+                /* Must be ignored on Data packets, cf. RFC 4342 8.3 and 8.5 */
+                if (packet_type == DCCP_PKT_DATA)
+                        break;
+                if (unlikely(optlen != 4)) {
                         DCCP_WARN("%s(%p), invalid len %d for %u\n",
-                                  dccp_role(sk), sk, len, option);
+                                  dccp_role(sk), sk, optlen, option);
                         return -EINVAL;
                 }
-                opt_val = ntohl(get_unaligned((__be32 *)value));
+                opt_val = ntohl(get_unaligned((__be32 *)optval));
 
                 if (option == TFRC_OPT_RECEIVE_RATE) {
                         opt_recv->ccid3or_receive_rate = opt_val;