Don't directly fetch multi-byte integers from packets.

[tcpdump] / print-ether.c

diff --git a/print-ether.c b/print-ether.c
index 20a2a65fb868eff1acb5c563bd89c8629983062d..581d688207e8e47162ea550ad05af6067805553f 100644 (file)
--- a/print-ether.c
+++ b/print-ether.c
@@ -33,6 +33,7 @@ static const char rcsid[] _U_ =
 #include <pcap.h>
 
 #include "interface.h"
+#include "extract.h"
 #include "addrtoname.h"
 #include "ethertype.h"
 
@@ -86,24 +87,27 @@ static inline void
 ether_hdr_print(register const u_char *bp, u_int length)
 {
        register const struct ether_header *ep;
+       u_int16_t ether_type;
+
        ep = (const struct ether_header *)bp;
 
        (void)printf("%s > %s",
                     etheraddr_string(ESRC(ep)),
                     etheraddr_string(EDST(ep)));
 
+       ether_type = EXTRACT_16BITS(&ep->ether_type);
        if (!qflag) {
-               if (ntohs(ep->ether_type) <= ETHERMTU)
+               if (ether_type <= ETHERMTU)
                          (void)printf(", 802.3");
                 else 
                          (void)printf(", ethertype %s (0x%04x)",
-                                      tok2str(ethertype_values,"Unknown", ntohs(ep->ether_type)),
-                                       ntohs(ep->ether_type));       
+                                      tok2str(ethertype_values,"Unknown", ether_type),
+                                       ether_type);
         } else {
-                if (ntohs(ep->ether_type) <= ETHERMTU)
+                if (ether_type <= ETHERMTU)
                           (void)printf(", 802.3");
                 else 
-                          (void)printf(", %s", tok2str(ethertype_values,"Unknown Ethertype (0x%04x)", ntohs(ep->ether_type)));  
+                          (void)printf(", %s", tok2str(ethertype_values,"Unknown Ethertype (0x%04x)", ether_type));
         }
 
        (void)printf(", length %u: ", length);
@@ -129,7 +133,7 @@ ether_print(const u_char *p, u_int length, u_int caplen)
        ep = (struct ether_header *)p;
        p += ETHER_HDRLEN;
 
-       ether_type = ntohs(ep->ether_type);
+       ether_type = EXTRACT_16BITS(&ep->ether_type);
 
        /*
         * Is it (gag) an 802.3 encapsulation?
@@ -226,13 +230,16 @@ ether_encap_print(u_short ether_type, const u_char *p,
                return (1);
 
        case ETHERTYPE_8021Q:
-               if (eflag)
-                   printf("vlan %u, p %u%s, ",
-                          ntohs(*(u_int16_t *)p) & 0xfff,
-                          ntohs(*(u_int16_t *)p) >> 13,
-                          (ntohs(*(u_int16_t *)p) & 0x1000) ? ", CFI" : "");
+               if (eflag) {
+                       u_int16_t tag = EXTRACT_16BITS(p);
+
+                       printf("vlan %u, p %u%s, ",
+                           tag & 0xfff,
+                           tag >> 13,
+                           (tag & 0x1000) ? ", CFI" : "");
+               }
 
-               ether_type = ntohs(*(u_int16_t *)(p + 2));
+               ether_type = EXTRACT_16BITS(p + 2);
                p += 4;
                length -= 4;
                caplen -= 4;
@@ -259,7 +266,7 @@ ether_encap_print(u_short ether_type, const u_char *p,
                return (1);
 
         case ETHERTYPE_JUMBO:
-                ether_type = ntohs(*(u_int16_t *)(p));
+                ether_type = EXTRACT_16BITS(p);
                 p += 2;
                 length -= 2;      
                 caplen -= 2;