tcpdump: print some more info about md5 auth in ospf

[David Gwynne]

seeing the key-id in particular helped me debug a problem here.

ok?

Index: ospf.h
===================================================================
RCS file: /cvs/src/usr.sbin/tcpdump/ospf.h,v
retrieving revision 1.10
diff -u -p -r1.10 ospf.h
--- ospf.h      4 Aug 2010 16:47:01 -0000       1.10
+++ ospf.h      10 Apr 2019 22:27:29 -0000
@@ -220,6 +220,13 @@ struct ospfhdr {
     } ospf_un ;
 } ;
 
+struct ospf_md5_authdata {
+       uint16_t        auth_md5_offset;
+       uint8_t         auth_keyid;
+       uint8_t         auth_len;
+       uint32_t        auth_seq;
+};
+
 #define        ospf_hello      ospf_un.un_hello
 #define        ospf_db         ospf_un.un_db
 #define        ospf_lsr        ospf_un.un_lsr
Index: print-ospf.c
===================================================================
RCS file: /cvs/src/usr.sbin/tcpdump/print-ospf.c,v
retrieving revision 1.20
diff -u -p -r1.20 print-ospf.c
--- print-ospf.c        16 Nov 2015 00:16:39 -0000      1.20
+++ print-ospf.c        10 Apr 2019 22:27:29 -0000
@@ -32,6 +32,7 @@
 
 #include <ctype.h>
 #include <stdio.h>
+#include <string.h>
 
 #include "interface.h"
 #include "addrtoname.h"
@@ -554,9 +555,20 @@ ospf_print(const u_char *bp, u_int lengt
                        printf("\"");
                        break;
 
-               case OSPF_AUTH_MD5:
-                       printf(" auth MD5");
+               case OSPF_AUTH_MD5: {
+                       struct ospf_md5_authdata auth;
+                       memcpy(&auth, op->ospf_authdata, sizeof(auth));
+
+                       printf(" auth MD5 key-id %u", auth.auth_keyid);
+                       if (vflag)
+                               printf(" seq %u", ntohl(auth.auth_seq));
+                       if (vflag > 1) {
+                               printf(" off %u len %u",
+                                   ntohs(auth.auth_md5_offset),
+                                   auth.auth_len);
+                       }
                        break;
+               }
 
                default:
                        printf(" ??authtype-%d??", ntohs(op->ospf_authtype));