[DCCP]: Miscellaneous code tidy-ups

This patch does not change code; it performs some trivial clean/tidy-ups:

  * removal of a `debug_prefix' string in favour of the
    already existing dccp_role(sk)

  * add documentation of structures and constants

  * separated out the cases for invalid packets (step 1
    of the packet validation)

  * removing duplicate statements

  * combining declaration & initialisation

Signed-off-by: Gerrit Renker <gerrit@erg.abdn.ac.uk>
Signed-off-by: Arnaldo Carvalho de Melo <acme@mandriva.com>

1 files changed, 19 insertions, 20 deletions

diff --git a/net/dccp/ipv4.c b/net/dccp/ipv4.c
index 61c09014dade..34d6d197c3b2 100644
--- a/net/dccp/ipv4.c
+++ b/net/dccp/ipv4.c
@@ -518,7 +518,7 @@ static void dccp_v4_ctl_send_reset(struct sk_buff *rxskb)
                                        sizeof(struct dccp_hdr_reset);
         struct sk_buff *skb;
         struct dst_entry *dst;
-        u64 seqno;
+        u64 seqno = 0;
 
         /* Never send a reset in response to a reset. */
         if (rxdh->dccph_type == DCCP_PKT_RESET)
@@ -552,13 +552,11 @@ static void dccp_v4_ctl_send_reset(struct sk_buff *rxskb)
                                 DCCP_SKB_CB(rxskb)->dccpd_reset_code;
 
         /* See "8.3.1. Abnormal Termination" in RFC 4340 */
-        seqno = 0;
         if (DCCP_SKB_CB(rxskb)->dccpd_ack_seq != DCCP_PKT_WITHOUT_ACK_SEQ)
                 dccp_set_seqno(&seqno, DCCP_SKB_CB(rxskb)->dccpd_ack_seq + 1);
 
         dccp_hdr_set_seq(dh, seqno);
-        dccp_hdr_set_ack(dccp_hdr_ack_bits(skb),
-                         DCCP_SKB_CB(rxskb)->dccpd_seq);
+        dccp_hdr_set_ack(dccp_hdr_ack_bits(skb), DCCP_SKB_CB(rxskb)->dccpd_seq);
 
         dccp_csum_outgoing(skb);
         dh->dccph_checksum = dccp_v4_csum_finish(skb, rxskb->nh.iph->saddr,
@@ -734,6 +732,11 @@ discard:
 
 EXPORT_SYMBOL_GPL(dccp_v4_do_rcv);
 
+/**
+ *      dccp_invalid_packet  -  check for malformed packets
+ *      Implements RFC 4340, 8.5:  Step 1: Check header basics
+ *      Packets that fail these checks are ignored and do not receive Resets.
+ */
 int dccp_invalid_packet(struct sk_buff *skb)
 {
         const struct dccp_hdr *dh;
@@ -742,6 +745,7 @@ int dccp_invalid_packet(struct sk_buff *skb)
         if (skb->pkt_type != PACKET_HOST)
                 return 1;
 
+        /* If the packet is shorter than 12 bytes, drop packet and return */
         if (!pskb_may_pull(skb, sizeof(struct dccp_hdr))) {
                 LIMIT_NETDEBUG(KERN_WARNING "DCCP: pskb_may_pull failed\n");
                 return 1;
@@ -749,42 +753,37 @@ int dccp_invalid_packet(struct sk_buff *skb)
 
         dh = dccp_hdr(skb);
 
-        /* If the packet type is not understood, drop packet and return */
+        /* If P.type is not understood, drop packet and return */
         if (dh->dccph_type >= DCCP_PKT_INVALID) {
                 LIMIT_NETDEBUG(KERN_WARNING "DCCP: invalid packet type\n");
                 return 1;
         }
 
         /*
-         * If P.Data Offset is too small for packet type, or too large for
-         * packet, drop packet and return
+         * If P.Data Offset is too small for packet type, drop packet and return
          */
         if (dh->dccph_doff < dccp_hdr_len(skb) / sizeof(u32)) {
                 LIMIT_NETDEBUG(KERN_WARNING "DCCP: P.Data Offset(%u) "
-                                            "too small 1\n",
-                               dh->dccph_doff);
+                                            "too small\n", dh->dccph_doff);
                 return 1;
         }
-
+        /*
+         * If P.Data Offset is too too large for packet, drop packet and return
+         */
         if (!pskb_may_pull(skb, dh->dccph_doff * sizeof(u32))) {
                 LIMIT_NETDEBUG(KERN_WARNING "DCCP: P.Data Offset(%u) "
-                                            "too small 2\n",
-                               dh->dccph_doff);
+                                            "too large\n", dh->dccph_doff);
                 return 1;
         }
 
-        dh = dccp_hdr(skb);
-
         /*
          * If P.type is not Data, Ack, or DataAck and P.X == 0 (the packet
          * has short sequence numbers), drop packet and return
          */
-        if (dh->dccph_x == 0 &&
-            dh->dccph_type != DCCP_PKT_DATA &&
-            dh->dccph_type != DCCP_PKT_ACK &&
-            dh->dccph_type != DCCP_PKT_DATAACK) {
-                LIMIT_NETDEBUG(KERN_WARNING "DCCP: P.type (%s) not Data, Ack "
-                                            "nor DataAck and P.X == 0\n",
+        if (dh->dccph_type >= DCCP_PKT_DATA    &&
+            dh->dccph_type <= DCCP_PKT_DATAACK && dh->dccph_x == 0)  {
+                LIMIT_NETDEBUG(KERN_WARNING "DCCP: P.type (%s) not Data||Ack||"
+                                            "DataAck, while P.X == 0\n",
                                dccp_packet_name(dh->dccph_type));
                 return 1;
         }