dccp: Increase the scope of variable-length htonl/ntohl functions

This extends the scope of two available functions,
encode|decode_value_var, to work up to 6 (8) bytes, to match maximum
requirements in the RFC.

These functions are going to be used both by general option processing
and feature negotiation code, hence declarations have been put into
feat.h.

Signed-off-by: Gerrit Renker <gerrit@erg.abdn.ac.uk>
Acked-by: Ian McDonald <ian.mcdonald@jandi.co.nz>
Acked-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

2 files changed, 28 insertions, 7 deletions

diff --git a/net/dccp/feat.h b/net/dccp/feat.h
index 093af1610d11..a8ab9e1e8b17 100644
--- a/net/dccp/feat.h
+++ b/net/dccp/feat.h
@@ -125,4 +125,18 @@ extern int  dccp_feat_clone(struct sock *oldsk, struct sock *newsk);
 extern int  dccp_feat_clone_list(struct list_head const *, struct list_head *);
 extern int  dccp_feat_init(struct sock *sk);
 
+/*
+ * Encoding variable-length options and their maximum length.
+ *
+ * This affects NN options (SP options are all u8) and other variable-length
+ * options (see table 3 in RFC 4340). The limit is currently given the Sequence
+ * Window NN value (sec. 7.5.2) and the NDP count (sec. 7.7) option, all other
+ * options consume less than 6 bytes (timestamps are 4 bytes).
+ * When updating this constant (e.g. due to new internet drafts / RFCs), make
+ * sure that you also update all code which refers to it.
+ */
+#define DCCP_OPTVAL_MAXLEN      6
+
+extern void dccp_encode_value_var(const u64 value, u8 *to, const u8 len);
+extern u64  dccp_decode_value_var(const u8 *bf, const u8 len);
 #endif /* _DCCP_FEAT_H */
diff --git a/net/dccp/options.c b/net/dccp/options.c
index 515ad45013ad..9cb0ff894052 100644
--- a/net/dccp/options.c
+++ b/net/dccp/options.c
@@ -29,16 +29,20 @@ int sysctl_dccp_feat_tx_ccid	      = DCCPF_INITIAL_CCID;
 int sysctl_dccp_feat_send_ack_vector = DCCPF_INITIAL_SEND_ACK_VECTOR;
 int sysctl_dccp_feat_send_ndp_count  = DCCPF_INITIAL_SEND_NDP_COUNT;
 
-static u32 dccp_decode_value_var(const unsigned char *bf, const u8 len)
+u64 dccp_decode_value_var(const u8 *bf, const u8 len)
 {
-        u32 value = 0;
+        u64 value = 0;
 
+        if (len >= DCCP_OPTVAL_MAXLEN)
+                value += ((u64)*bf++) << 40;
+        if (len > 4)
+                value += ((u64)*bf++) << 32;
         if (len > 3)
-                value += *bf++ << 24;
+                value += ((u64)*bf++) << 24;
         if (len > 2)
-                value += *bf++ << 16;
+                value += ((u64)*bf++) << 16;
         if (len > 1)
-                value += *bf++ << 8;
+                value += ((u64)*bf++) << 8;
         if (len > 0)
                 value += *bf;
 
@@ -298,9 +302,12 @@ out_invalid_option:
 
 EXPORT_SYMBOL_GPL(dccp_parse_options);
 
-static void dccp_encode_value_var(const u32 value, unsigned char *to,
-                                  const unsigned int len)
+void dccp_encode_value_var(const u64 value, u8 *to, const u8 len)
 {
+        if (len >= DCCP_OPTVAL_MAXLEN)
+                *to++ = (value & 0xFF0000000000ull) >> 40;
+        if (len > 4)
+                *to++ = (value & 0xFF00000000ull) >> 32;
         if (len > 3)
                 *to++ = (value & 0xFF000000) >> 24;
         if (len > 2)