]> The Tcpdump Group git mirrors - tcpdump/blobdiff - print-l2tp.c
Use more the EXTRACT_U_1() macro (40/n)
[tcpdump] / print-l2tp.c
index 514eb2c5f4519f5876e948761d4a1b843ad279a2..6cf0c0adfb1104c17b0d51b69071008913984bfd 100644 (file)
  * L2TP support contributed by Motonori Shindo ([email protected])
  */
 
+/* \summary: Layer Two Tunneling Protocol (L2TP) printer */
+
 #ifdef HAVE_CONFIG_H
 #include "config.h"
 #endif
 
-#include <tcpdump-stdinc.h>
+#include <netdissect-stdinc.h>
 
-#include "interface.h"
+#include "netdissect.h"
 #include "extract.h"
 
 #define L2TP_FLAG_TYPE         0x8000  /* Type (0=Data, 1=Control) */
@@ -266,7 +268,8 @@ print_string(netdissect_options *ndo, const u_char *dat, u_int length)
 {
        u_int i;
        for (i=0; i<length; i++) {
-               ND_PRINT((ndo, "%c", *dat++));
+               ND_PRINT((ndo, "%c", EXTRACT_U_1(dat)));
+               dat++;
        }
 }
 
@@ -275,32 +278,37 @@ print_octets(netdissect_options *ndo, const u_char *dat, u_int length)
 {
        u_int i;
        for (i=0; i<length; i++) {
-               ND_PRINT((ndo, "%02x", *dat++));
+               ND_PRINT((ndo, "%02x", EXTRACT_U_1(dat)));
+               dat++;
        }
 }
 
 static void
 print_16bits_val(netdissect_options *ndo, const uint16_t *dat)
 {
-       ND_PRINT((ndo, "%u", EXTRACT_16BITS(dat)));
+       ND_PRINT((ndo, "%u", EXTRACT_BE_U_2(dat)));
 }
 
 static void
 print_32bits_val(netdissect_options *ndo, const uint32_t *dat)
 {
-       ND_PRINT((ndo, "%lu", (u_long)EXTRACT_32BITS(dat)));
+       ND_PRINT((ndo, "%lu", (u_long) EXTRACT_BE_U_4(dat)));
 }
 
 /***********************************/
 /* AVP-specific print out routines */
 /***********************************/
 static void
-l2tp_msgtype_print(netdissect_options *ndo, const u_char *dat)
+l2tp_msgtype_print(netdissect_options *ndo, const u_char *dat, u_int length)
 {
        const uint16_t *ptr = (const uint16_t *)dat;
 
+       if (length < 2) {
+               ND_PRINT((ndo, "AVP too short"));
+               return;
+       }
        ND_PRINT((ndo, "%s", tok2str(l2tp_msgtype2str, "MSGTYPE-#%u",
-           EXTRACT_16BITS(ptr))));
+           EXTRACT_BE_U_2(ptr))));
 }
 
 static void
@@ -308,45 +316,74 @@ l2tp_result_code_print(netdissect_options *ndo, const u_char *dat, u_int length)
 {
        const uint16_t *ptr = (const uint16_t *)dat;
 
-       ND_PRINT((ndo, "%u", EXTRACT_16BITS(ptr))); ptr++;      /* Result Code */
-       if (length > 2) {                               /* Error Code (opt) */
-               ND_PRINT((ndo, "/%u", EXTRACT_16BITS(ptr))); ptr++;
+       /* Result Code */
+       if (length < 2) {
+               ND_PRINT((ndo, "AVP too short"));
+               return;
        }
-       if (length > 4) {                               /* Error Message (opt) */
-               ND_PRINT((ndo, " "));
-               print_string(ndo, (const u_char *)ptr, length - 4);
+       ND_PRINT((ndo, "%u", EXTRACT_BE_U_2(ptr)));
+       ptr++;
+       length -= 2;
+
+       /* Error Code (opt) */
+       if (length == 0)
+               return;
+       if (length < 2) {
+               ND_PRINT((ndo, " AVP too short"));
+               return;
        }
+       ND_PRINT((ndo, "/%u", EXTRACT_BE_U_2(ptr)));
+       ptr++;
+       length -= 2;
+
+       /* Error Message (opt) */
+       if (length == 0)
+               return;
+       ND_PRINT((ndo, " "));
+       print_string(ndo, (const u_char *)ptr, length);
 }
 
 static void
-l2tp_proto_ver_print(netdissect_options *ndo, const uint16_t *dat)
+l2tp_proto_ver_print(netdissect_options *ndo, const uint16_t *dat, u_int length)
 {
-       ND_PRINT((ndo, "%u.%u", (EXTRACT_16BITS(dat) >> 8),
-           (EXTRACT_16BITS(dat) & 0xff)));
+       if (length < 2) {
+               ND_PRINT((ndo, "AVP too short"));
+               return;
+       }
+       ND_PRINT((ndo, "%u.%u", (EXTRACT_BE_U_2(dat) >> 8),
+                 (EXTRACT_BE_U_2(dat) & 0xff)));
 }
 
 static void
-l2tp_framing_cap_print(netdissect_options *ndo, const u_char *dat)
+l2tp_framing_cap_print(netdissect_options *ndo, const u_char *dat, u_int length)
 {
        const uint32_t *ptr = (const uint32_t *)dat;
 
-       if (EXTRACT_32BITS(ptr) &  L2TP_FRAMING_CAP_ASYNC_MASK) {
+       if (length < 4) {
+               ND_PRINT((ndo, "AVP too short"));
+               return;
+       }
+       if (EXTRACT_BE_U_4(ptr) &  L2TP_FRAMING_CAP_ASYNC_MASK) {
                ND_PRINT((ndo, "A"));
        }
-       if (EXTRACT_32BITS(ptr) &  L2TP_FRAMING_CAP_SYNC_MASK) {
+       if (EXTRACT_BE_U_4(ptr) &  L2TP_FRAMING_CAP_SYNC_MASK) {
                ND_PRINT((ndo, "S"));
        }
 }
 
 static void
-l2tp_bearer_cap_print(netdissect_options *ndo, const u_char *dat)
+l2tp_bearer_cap_print(netdissect_options *ndo, const u_char *dat, u_int length)
 {
        const uint32_t *ptr = (const uint32_t *)dat;
 
-       if (EXTRACT_32BITS(ptr) &  L2TP_BEARER_CAP_ANALOG_MASK) {
+       if (length < 4) {
+               ND_PRINT((ndo, "AVP too short"));
+               return;
+       }
+       if (EXTRACT_BE_U_4(ptr) &  L2TP_BEARER_CAP_ANALOG_MASK) {
                ND_PRINT((ndo, "A"));
        }
-       if (EXTRACT_32BITS(ptr) &  L2TP_BEARER_CAP_DIGITAL_MASK) {
+       if (EXTRACT_BE_U_4(ptr) &  L2TP_BEARER_CAP_DIGITAL_MASK) {
                ND_PRINT((ndo, "D"));
        }
 }
@@ -354,36 +391,50 @@ l2tp_bearer_cap_print(netdissect_options *ndo, const u_char *dat)
 static void
 l2tp_q931_cc_print(netdissect_options *ndo, const u_char *dat, u_int length)
 {
+       if (length < 3) {
+               ND_PRINT((ndo, "AVP too short"));
+               return;
+       }
        print_16bits_val(ndo, (const uint16_t *)dat);
-       ND_PRINT((ndo, ", %02x", dat[2]));
-       if (length > 3) {
+       ND_PRINT((ndo, ", %02x", EXTRACT_U_1(dat + 2)));
+       dat += 3;
+       length -= 3;
+       if (length != 0) {
                ND_PRINT((ndo, " "));
-               print_string(ndo, dat+3, length-3);
+               print_string(ndo, dat, length);
        }
 }
 
 static void
-l2tp_bearer_type_print(netdissect_options *ndo, const u_char *dat)
+l2tp_bearer_type_print(netdissect_options *ndo, const u_char *dat, u_int length)
 {
        const uint32_t *ptr = (const uint32_t *)dat;
 
-       if (EXTRACT_32BITS(ptr) &  L2TP_BEARER_TYPE_ANALOG_MASK) {
+       if (length < 4) {
+               ND_PRINT((ndo, "AVP too short"));
+               return;
+       }
+       if (EXTRACT_BE_U_4(ptr) &  L2TP_BEARER_TYPE_ANALOG_MASK) {
                ND_PRINT((ndo, "A"));
        }
-       if (EXTRACT_32BITS(ptr) &  L2TP_BEARER_TYPE_DIGITAL_MASK) {
+       if (EXTRACT_BE_U_4(ptr) &  L2TP_BEARER_TYPE_DIGITAL_MASK) {
                ND_PRINT((ndo, "D"));
        }
 }
 
 static void
-l2tp_framing_type_print(netdissect_options *ndo, const u_char *dat)
+l2tp_framing_type_print(netdissect_options *ndo, const u_char *dat, u_int length)
 {
        const uint32_t *ptr = (const uint32_t *)dat;
 
-       if (EXTRACT_32BITS(ptr) &  L2TP_FRAMING_TYPE_ASYNC_MASK) {
+       if (length < 4) {
+               ND_PRINT((ndo, "AVP too short"));
+               return;
+       }
+       if (EXTRACT_BE_U_4(ptr) &  L2TP_FRAMING_TYPE_ASYNC_MASK) {
                ND_PRINT((ndo, "A"));
        }
-       if (EXTRACT_32BITS(ptr) &  L2TP_FRAMING_TYPE_SYNC_MASK) {
+       if (EXTRACT_BE_U_4(ptr) &  L2TP_FRAMING_TYPE_SYNC_MASK) {
                ND_PRINT((ndo, "S"));
        }
 }
@@ -395,69 +446,119 @@ l2tp_packet_proc_delay_print(netdissect_options *ndo)
 }
 
 static void
-l2tp_proxy_auth_type_print(netdissect_options *ndo, const u_char *dat)
+l2tp_proxy_auth_type_print(netdissect_options *ndo, const u_char *dat, u_int length)
 {
        const uint16_t *ptr = (const uint16_t *)dat;
 
+       if (length < 2) {
+               ND_PRINT((ndo, "AVP too short"));
+               return;
+       }
        ND_PRINT((ndo, "%s", tok2str(l2tp_authentype2str,
-                            "AuthType-#%u", EXTRACT_16BITS(ptr))));
+                            "AuthType-#%u", EXTRACT_BE_U_2(ptr))));
 }
 
 static void
-l2tp_proxy_auth_id_print(netdissect_options *ndo, const u_char *dat)
+l2tp_proxy_auth_id_print(netdissect_options *ndo, const u_char *dat, u_int length)
 {
        const uint16_t *ptr = (const uint16_t *)dat;
 
-       ND_PRINT((ndo, "%u", EXTRACT_16BITS(ptr) & L2TP_PROXY_AUTH_ID_MASK));
+       if (length < 2) {
+               ND_PRINT((ndo, "AVP too short"));
+               return;
+       }
+       ND_PRINT((ndo, "%u", EXTRACT_BE_U_2(ptr) & L2TP_PROXY_AUTH_ID_MASK));
 }
 
 static void
-l2tp_call_errors_print(netdissect_options *ndo, const u_char *dat)
+l2tp_call_errors_print(netdissect_options *ndo, const u_char *dat, u_int length)
 {
        const uint16_t *ptr = (const uint16_t *)dat;
        uint16_t val_h, val_l;
 
+       if (length < 2) {
+               ND_PRINT((ndo, "AVP too short"));
+               return;
+       }
        ptr++;          /* skip "Reserved" */
+       length -= 2;
 
-       val_h = EXTRACT_16BITS(ptr); ptr++;
-       val_l = EXTRACT_16BITS(ptr); ptr++;
+       if (length < 4) {
+               ND_PRINT((ndo, "AVP too short"));
+               return;
+       }
+       val_h = EXTRACT_BE_U_2(ptr); ptr++; length -= 2;
+       val_l = EXTRACT_BE_U_2(ptr); ptr++; length -= 2;
        ND_PRINT((ndo, "CRCErr=%u ", (val_h<<16) + val_l));
 
-       val_h = EXTRACT_16BITS(ptr); ptr++;
-       val_l = EXTRACT_16BITS(ptr); ptr++;
+       if (length < 4) {
+               ND_PRINT((ndo, "AVP too short"));
+               return;
+       }
+       val_h = EXTRACT_BE_U_2(ptr); ptr++; length -= 2;
+       val_l = EXTRACT_BE_U_2(ptr); ptr++; length -= 2;
        ND_PRINT((ndo, "FrameErr=%u ", (val_h<<16) + val_l));
 
-       val_h = EXTRACT_16BITS(ptr); ptr++;
-       val_l = EXTRACT_16BITS(ptr); ptr++;
+       if (length < 4) {
+               ND_PRINT((ndo, "AVP too short"));
+               return;
+       }
+       val_h = EXTRACT_BE_U_2(ptr); ptr++; length -= 2;
+       val_l = EXTRACT_BE_U_2(ptr); ptr++; length -= 2;
        ND_PRINT((ndo, "HardOver=%u ", (val_h<<16) + val_l));
 
-       val_h = EXTRACT_16BITS(ptr); ptr++;
-       val_l = EXTRACT_16BITS(ptr); ptr++;
+       if (length < 4) {
+               ND_PRINT((ndo, "AVP too short"));
+               return;
+       }
+       val_h = EXTRACT_BE_U_2(ptr); ptr++; length -= 2;
+       val_l = EXTRACT_BE_U_2(ptr); ptr++; length -= 2;
        ND_PRINT((ndo, "BufOver=%u ", (val_h<<16) + val_l));
 
-       val_h = EXTRACT_16BITS(ptr); ptr++;
-       val_l = EXTRACT_16BITS(ptr); ptr++;
+       if (length < 4) {
+               ND_PRINT((ndo, "AVP too short"));
+               return;
+       }
+       val_h = EXTRACT_BE_U_2(ptr); ptr++; length -= 2;
+       val_l = EXTRACT_BE_U_2(ptr); ptr++; length -= 2;
        ND_PRINT((ndo, "Timeout=%u ", (val_h<<16) + val_l));
 
-       val_h = EXTRACT_16BITS(ptr); ptr++;
-       val_l = EXTRACT_16BITS(ptr); ptr++;
+       if (length < 4) {
+               ND_PRINT((ndo, "AVP too short"));
+               return;
+       }
+       val_h = EXTRACT_BE_U_2(ptr); ptr++;
+       val_l = EXTRACT_BE_U_2(ptr); ptr++;
        ND_PRINT((ndo, "AlignErr=%u ", (val_h<<16) + val_l));
 }
 
 static void
-l2tp_accm_print(netdissect_options *ndo, const u_char *dat)
+l2tp_accm_print(netdissect_options *ndo, const u_char *dat, u_int length)
 {
        const uint16_t *ptr = (const uint16_t *)dat;
        uint16_t val_h, val_l;
 
+       if (length < 2) {
+               ND_PRINT((ndo, "AVP too short"));
+               return;
+       }
        ptr++;          /* skip "Reserved" */
+       length -= 2;
 
-       val_h = EXTRACT_16BITS(ptr); ptr++;
-       val_l = EXTRACT_16BITS(ptr); ptr++;
+       if (length < 4) {
+               ND_PRINT((ndo, "AVP too short"));
+               return;
+       }
+       val_h = EXTRACT_BE_U_2(ptr); ptr++; length -= 2;
+       val_l = EXTRACT_BE_U_2(ptr); ptr++; length -= 2;
        ND_PRINT((ndo, "send=%08x ", (val_h<<16) + val_l));
 
-       val_h = EXTRACT_16BITS(ptr); ptr++;
-       val_l = EXTRACT_16BITS(ptr); ptr++;
+       if (length < 4) {
+               ND_PRINT((ndo, "AVP too short"));
+               return;
+       }
+       val_h = EXTRACT_BE_U_2(ptr); ptr++;
+       val_l = EXTRACT_BE_U_2(ptr); ptr++;
        ND_PRINT((ndo, "recv=%08x ", (val_h<<16) + val_l));
 }
 
@@ -466,14 +567,27 @@ l2tp_ppp_discon_cc_print(netdissect_options *ndo, const u_char *dat, u_int lengt
 {
        const uint16_t *ptr = (const uint16_t *)dat;
 
-       ND_PRINT((ndo, "%04x, ", EXTRACT_16BITS(ptr))); ptr++;  /* Disconnect Code */
-       ND_PRINT((ndo, "%04x ",  EXTRACT_16BITS(ptr))); ptr++;  /* Control Protocol Number */
+       if (length < 5) {
+               ND_PRINT((ndo, "AVP too short"));
+               return;
+       }
+       /* Disconnect Code */
+       ND_PRINT((ndo, "%04x, ", EXTRACT_BE_U_2(dat)));
+       dat += 2;
+       length -= 2;
+       /* Control Protocol Number */
+       ND_PRINT((ndo, "%04x ",  EXTRACT_BE_U_2(dat)));
+       dat += 2;
+       length -= 2;
+       /* Direction */
        ND_PRINT((ndo, "%s", tok2str(l2tp_cc_direction2str,
-                            "Direction-#%u", *((const u_char *)ptr++))));
+                            "Direction-#%u", EXTRACT_U_1(ptr))));
+       ptr++;
+       length--;
 
-       if (length > 5) {
+       if (length != 0) {
                ND_PRINT((ndo, " "));
-               print_string(ndo, (const u_char *)ptr, length-5);
+               print_string(ndo, (const u_char *)ptr, length);
        }
 }
 
@@ -492,7 +606,7 @@ l2tp_avp_print(netdissect_options *ndo, const u_char *dat, int length)
        ND_PRINT((ndo, " "));
 
        ND_TCHECK(*ptr);        /* Flags & Length */
-       len = EXTRACT_16BITS(ptr) & L2TP_AVP_HDR_LEN_MASK;
+       len = EXTRACT_BE_U_2(ptr) & L2TP_AVP_HDR_LEN_MASK;
 
        /* If it is not long enough to contain the header, we'll give up. */
        if (len < 6)
@@ -506,28 +620,33 @@ l2tp_avp_print(netdissect_options *ndo, const u_char *dat, int length)
        /* If it goes past the end of the remaining length of the captured
           data, we'll give up. */
        ND_TCHECK2(*ptr, len);
-       /* After this point, no need to worry about truncation */
 
-       if (EXTRACT_16BITS(ptr) & L2TP_AVP_HDR_FLAG_MANDATORY) {
+       /*
+        * After this point, we don't need to check whether we go past
+        * the length of the captured data; however, we *do* need to
+        * check whether we go past the end of the AVP.
+        */
+
+       if (EXTRACT_BE_U_2(ptr) & L2TP_AVP_HDR_FLAG_MANDATORY) {
                ND_PRINT((ndo, "*"));
        }
-       if (EXTRACT_16BITS(ptr) & L2TP_AVP_HDR_FLAG_HIDDEN) {
+       if (EXTRACT_BE_U_2(ptr) & L2TP_AVP_HDR_FLAG_HIDDEN) {
                hidden = TRUE;
                ND_PRINT((ndo, "?"));
        }
        ptr++;
 
-       if (EXTRACT_16BITS(ptr)) {
+       if (EXTRACT_BE_U_2(ptr)) {
                /* Vendor Specific Attribute */
-               ND_PRINT((ndo, "VENDOR%04x:", EXTRACT_16BITS(ptr))); ptr++;
-               ND_PRINT((ndo, "ATTR%04x", EXTRACT_16BITS(ptr))); ptr++;
+               ND_PRINT((ndo, "VENDOR%04x:", EXTRACT_BE_U_2(ptr))); ptr++;
+               ND_PRINT((ndo, "ATTR%04x", EXTRACT_BE_U_2(ptr))); ptr++;
                ND_PRINT((ndo, "("));
                print_octets(ndo, (const u_char *)ptr, len-6);
                ND_PRINT((ndo, ")"));
        } else {
                /* IETF-defined Attributes */
                ptr++;
-               attr_type = EXTRACT_16BITS(ptr); ptr++;
+               attr_type = EXTRACT_BE_U_2(ptr); ptr++;
                ND_PRINT((ndo, "%s", tok2str(l2tp_avp2str, "AVP-#%u", attr_type)));
                ND_PRINT((ndo, "("));
                if (hidden) {
@@ -535,27 +654,35 @@ l2tp_avp_print(netdissect_options *ndo, const u_char *dat, int length)
                } else {
                        switch (attr_type) {
                        case L2TP_AVP_MSGTYPE:
-                               l2tp_msgtype_print(ndo, (const u_char *)ptr);
+                               l2tp_msgtype_print(ndo, (const u_char *)ptr, len-6);
                                break;
                        case L2TP_AVP_RESULT_CODE:
                                l2tp_result_code_print(ndo, (const u_char *)ptr, len-6);
                                break;
                        case L2TP_AVP_PROTO_VER:
-                               l2tp_proto_ver_print(ndo, ptr);
+                               l2tp_proto_ver_print(ndo, ptr, len-6);
                                break;
                        case L2TP_AVP_FRAMING_CAP:
-                               l2tp_framing_cap_print(ndo, (const u_char *)ptr);
+                               l2tp_framing_cap_print(ndo, (const u_char *)ptr, len-6);
                                break;
                        case L2TP_AVP_BEARER_CAP:
-                               l2tp_bearer_cap_print(ndo, (const u_char *)ptr);
+                               l2tp_bearer_cap_print(ndo, (const u_char *)ptr, len-6);
                                break;
                        case L2TP_AVP_TIE_BREAKER:
+                               if (len-6 < 8) {
+                                       ND_PRINT((ndo, "AVP too short"));
+                                       break;
+                               }
                                print_octets(ndo, (const u_char *)ptr, 8);
                                break;
                        case L2TP_AVP_FIRM_VER:
                        case L2TP_AVP_ASSND_TUN_ID:
                        case L2TP_AVP_RECV_WIN_SIZE:
                        case L2TP_AVP_ASSND_SESS_ID:
+                               if (len-6 < 2) {
+                                       ND_PRINT((ndo, "AVP too short"));
+                                       break;
+                               }
                                print_16bits_val(ndo, ptr);
                                break;
                        case L2TP_AVP_HOST_NAME:
@@ -580,6 +707,10 @@ l2tp_avp_print(netdissect_options *ndo, const u_char *dat, int length)
                                l2tp_q931_cc_print(ndo, (const u_char *)ptr, len-6);
                                break;
                        case L2TP_AVP_CHALLENGE_RESP:
+                               if (len-6 < 16) {
+                                       ND_PRINT((ndo, "AVP too short"));
+                                       break;
+                               }
                                print_octets(ndo, (const u_char *)ptr, 16);
                                break;
                        case L2TP_AVP_CALL_SER_NUM:
@@ -588,28 +719,32 @@ l2tp_avp_print(netdissect_options *ndo, const u_char *dat, int length)
                        case L2TP_AVP_TX_CONN_SPEED:
                        case L2TP_AVP_PHY_CHANNEL_ID:
                        case L2TP_AVP_RX_CONN_SPEED:
+                               if (len-6 < 4) {
+                                       ND_PRINT((ndo, "AVP too short"));
+                                       break;
+                               }
                                print_32bits_val(ndo, (const uint32_t *)ptr);
                                break;
                        case L2TP_AVP_BEARER_TYPE:
-                               l2tp_bearer_type_print(ndo, (const u_char *)ptr);
+                               l2tp_bearer_type_print(ndo, (const u_char *)ptr, len-6);
                                break;
                        case L2TP_AVP_FRAMING_TYPE:
-                               l2tp_framing_type_print(ndo, (const u_char *)ptr);
+                               l2tp_framing_type_print(ndo, (const u_char *)ptr, len-6);
                                break;
                        case L2TP_AVP_PACKET_PROC_DELAY:
                                l2tp_packet_proc_delay_print(ndo);
                                break;
                        case L2TP_AVP_PROXY_AUTH_TYPE:
-                               l2tp_proxy_auth_type_print(ndo, (const u_char *)ptr);
+                               l2tp_proxy_auth_type_print(ndo, (const u_char *)ptr, len-6);
                                break;
                        case L2TP_AVP_PROXY_AUTH_ID:
-                               l2tp_proxy_auth_id_print(ndo, (const u_char *)ptr);
+                               l2tp_proxy_auth_id_print(ndo, (const u_char *)ptr, len-6);
                                break;
                        case L2TP_AVP_CALL_ERRORS:
-                               l2tp_call_errors_print(ndo, (const u_char *)ptr);
+                               l2tp_call_errors_print(ndo, (const u_char *)ptr, len-6);
                                break;
                        case L2TP_AVP_ACCM:
-                               l2tp_accm_print(ndo, (const u_char *)ptr);
+                               l2tp_accm_print(ndo, (const u_char *)ptr, len-6);
                                break;
                        case L2TP_AVP_SEQ_REQUIRED:
                                break;  /* No Attribute Value */
@@ -642,10 +777,10 @@ l2tp_print(netdissect_options *ndo, const u_char *dat, u_int length)
 
        flag_t = flag_l = flag_s = flag_o = FALSE;
 
-       ND_TCHECK2(*ptr, 2);    /* Flags & Version */
-       if ((EXTRACT_16BITS(ptr) & L2TP_VERSION_MASK) == L2TP_VERSION_L2TP) {
+       ND_TCHECK_2(ptr);       /* Flags & Version */
+       if ((EXTRACT_BE_U_2(ptr) & L2TP_VERSION_MASK) == L2TP_VERSION_L2TP) {
                ND_PRINT((ndo, " l2tp:"));
-       } else if ((EXTRACT_16BITS(ptr) & L2TP_VERSION_MASK) == L2TP_VERSION_L2F) {
+       } else if ((EXTRACT_BE_U_2(ptr) & L2TP_VERSION_MASK) == L2TP_VERSION_L2F) {
                ND_PRINT((ndo, " l2f:"));
                return;         /* nothing to do */
        } else {
@@ -654,23 +789,23 @@ l2tp_print(netdissect_options *ndo, const u_char *dat, u_int length)
        }
 
        ND_PRINT((ndo, "["));
-       if (EXTRACT_16BITS(ptr) & L2TP_FLAG_TYPE) {
+       if (EXTRACT_BE_U_2(ptr) & L2TP_FLAG_TYPE) {
                flag_t = TRUE;
                ND_PRINT((ndo, "T"));
        }
-       if (EXTRACT_16BITS(ptr) & L2TP_FLAG_LENGTH) {
+       if (EXTRACT_BE_U_2(ptr) & L2TP_FLAG_LENGTH) {
                flag_l = TRUE;
                ND_PRINT((ndo, "L"));
        }
-       if (EXTRACT_16BITS(ptr) & L2TP_FLAG_SEQUENCE) {
+       if (EXTRACT_BE_U_2(ptr) & L2TP_FLAG_SEQUENCE) {
                flag_s = TRUE;
                ND_PRINT((ndo, "S"));
        }
-       if (EXTRACT_16BITS(ptr) & L2TP_FLAG_OFFSET) {
+       if (EXTRACT_BE_U_2(ptr) & L2TP_FLAG_OFFSET) {
                flag_o = TRUE;
                ND_PRINT((ndo, "O"));
        }
-       if (EXTRACT_16BITS(ptr) & L2TP_FLAG_PRIORITY)
+       if (EXTRACT_BE_U_2(ptr) & L2TP_FLAG_PRIORITY)
                ND_PRINT((ndo, "P"));
        ND_PRINT((ndo, "]"));
 
@@ -678,37 +813,37 @@ l2tp_print(netdissect_options *ndo, const u_char *dat, u_int length)
        cnt += 2;
 
        if (flag_l) {
-               ND_TCHECK2(*ptr, 2);    /* Length */
-               l2tp_len = EXTRACT_16BITS(ptr);
+               ND_TCHECK_2(ptr);       /* Length */
+               l2tp_len = EXTRACT_BE_U_2(ptr);
                ptr += 2;
                cnt += 2;
        } else {
                l2tp_len = 0;
        }
 
-       ND_TCHECK2(*ptr, 2);            /* Tunnel ID */
-       ND_PRINT((ndo, "(%u/", EXTRACT_16BITS(ptr)));
+       ND_TCHECK_2(ptr);               /* Tunnel ID */
+       ND_PRINT((ndo, "(%u/", EXTRACT_BE_U_2(ptr)));
        ptr += 2;
        cnt += 2;
-       ND_TCHECK2(*ptr, 2);            /* Session ID */
-       ND_PRINT((ndo, "%u)",  EXTRACT_16BITS(ptr)));
+       ND_TCHECK_2(ptr);               /* Session ID */
+       ND_PRINT((ndo, "%u)",  EXTRACT_BE_U_2(ptr)));
        ptr += 2;
        cnt += 2;
 
        if (flag_s) {
-               ND_TCHECK2(*ptr, 2);    /* Ns */
-               ND_PRINT((ndo, "Ns=%u,", EXTRACT_16BITS(ptr)));
+               ND_TCHECK_2(ptr);       /* Ns */
+               ND_PRINT((ndo, "Ns=%u,", EXTRACT_BE_U_2(ptr)));
                ptr += 2;
                cnt += 2;
-               ND_TCHECK2(*ptr, 2);    /* Nr */
-               ND_PRINT((ndo, "Nr=%u",  EXTRACT_16BITS(ptr)));
+               ND_TCHECK_2(ptr);       /* Nr */
+               ND_PRINT((ndo, "Nr=%u",  EXTRACT_BE_U_2(ptr)));
                ptr += 2;
                cnt += 2;
        }
 
        if (flag_o) {
-               ND_TCHECK2(*ptr, 2);    /* Offset Size */
-               pad =  EXTRACT_16BITS(ptr);
+               ND_TCHECK_2(ptr);       /* Offset Size */
+               pad =  EXTRACT_BE_U_2(ptr);
                ptr += (2 + pad);
                cnt += (2 + pad);
        }