Clean up the handling of the IGMP header.

Extract the major and minor versions separately, rather than stuffing
them, along with other unused information, into a 32-bit word and then
pulling that word back apart.

Don't use a global variable to store the major and minor versions, pass
them as arguments.

Note where the protocol is specified.

diff --git a/print-dvmrp.c b/print-dvmrp.c
index 60f836e8ea1d6f5a057f342729bc77a769ba8cb3..e6e87667123c07b4f1b93a9aae921c8037263fe2 100644 (file)
--- a/print-dvmrp.c
+++ b/print-dvmrp.c
@@ -32,6 +32,8 @@
 #include "addrtoname.h"
 
 /*
+ * See: RFC 1075 and draft-ietf-idmr-dvmrp-v3
+ *
  * DVMRP message types and flag values shamelessly stolen from
  * mrouted/dvmrp.h.
  */
@@ -58,19 +60,18 @@
 static int print_probe(netdissect_options *, const u_char *, const u_char *, u_int);
 static int print_report(netdissect_options *, const u_char *, const u_char *, u_int);
 static int print_neighbors(netdissect_options *, const u_char *, const u_char *, u_int);
-static int print_neighbors2(netdissect_options *, const u_char *, const u_char *, u_int);
+static int print_neighbors2(netdissect_options *, const u_char *, const u_char *, u_int, uint8_t, uint8_t);
 static int print_prune(netdissect_options *, const u_char *);
 static int print_graft(netdissect_options *, const u_char *);
 static int print_graft_ack(netdissect_options *, const u_char *);
 
-static uint32_t target_level;
-
 void
 dvmrp_print(netdissect_options *ndo,
             register const u_char *bp, register u_int len)
 {
        register const u_char *ep;
        register u_char type;
+       uint8_t major_version, minor_version;
 
        ep = (const u_char *)ndo->ndo_snapend;
        if (bp >= ep)
@@ -118,15 +119,15 @@ dvmrp_print(netdissect_options *ndo,
        case DVMRP_NEIGHBORS2:
                ND_PRINT((ndo, " Neighbors2"));
                /*
-                * extract version and capabilities from IGMP group
-                * address field
+                * extract version from IGMP group address field
                 */
                bp -= 4;
                ND_TCHECK2(bp[0], 4);
-               target_level = (bp[0] << 24) | (bp[1] << 16) |
-                   (bp[2] << 8) | bp[3];
+               major_version = *(bp + 3);
+               minor_version = *(bp + 2);
                bp += 4;
-               if (print_neighbors2(ndo, bp, ep, len) < 0)
+               if (print_neighbors2(ndo, bp, ep, len, major_version,
+                   minor_version) < 0)
                        goto trunc;
                break;
 
@@ -283,15 +284,14 @@ trunc:
 static int
 print_neighbors2(netdissect_options *ndo,
                  register const u_char *bp, register const u_char *ep,
-                 register u_int len)
+                 register u_int len, uint8_t major_version,
+                 uint8_t minor_version)
 {
        const u_char *laddr;
        register u_char metric, thresh, flags;
        register int ncount;
 
-       ND_PRINT((ndo, " (v %d.%d):",
-              (int)target_level & 0xff,
-              (int)(target_level >> 8) & 0xff));
+       ND_PRINT((ndo, " (v %d.%d):", major_version, minor_version));
 
        while (len > 0 && bp < ep) {
                ND_TCHECK2(bp[0], 8);