More EXTRACT_U_1() and ND_TCHECK_n, clean up signedness, add length checks.

Add more EXTRACT_U_1() calls.

Use ND_TCHECK_n() where appropriate.

Use unsigned values wherever appropriate.

Make sure the claimed length of a control protocol packet doesn't go
past the claimed length of the on-the-wire packet.

diff --git a/print-ppp.c b/print-ppp.c
index 9bcb2f9df8063ecb1938f0f052a93dd62f557ec3..3ab4c96dc4ffe2b620d6e1c32f5d152dbd14c1d8 100644 (file)
--- a/print-ppp.c
+++ b/print-ppp.c
@@ -402,22 +402,22 @@ static const struct tok papcode_values[] = {
 #define BAP_CSIND      7
 #define BAP_CSRES      8
 
-static int print_lcp_config_options(netdissect_options *, const u_char *p, int);
-static int print_ipcp_config_options(netdissect_options *, const u_char *p, int);
-static int print_ip6cp_config_options(netdissect_options *, const u_char *p, int);
-static int print_ccp_config_options(netdissect_options *, const u_char *p, int);
-static int print_bacp_config_options(netdissect_options *, const u_char *p, int);
-static void handle_ppp(netdissect_options *, u_int proto, const u_char *p, int length);
+static u_int print_lcp_config_options(netdissect_options *, const u_char *p, u_int);
+static u_int print_ipcp_config_options(netdissect_options *, const u_char *p, u_int);
+static u_int print_ip6cp_config_options(netdissect_options *, const u_char *p, u_int);
+static u_int print_ccp_config_options(netdissect_options *, const u_char *p, u_int);
+static u_int print_bacp_config_options(netdissect_options *, const u_char *p, u_int);
+static void handle_ppp(netdissect_options *, u_int proto, const u_char *p, u_int length);
 
 /* generic Control Protocol (e.g. LCP, IPCP, CCP, etc.) handler */
 static void
 handle_ctrl_proto(netdissect_options *ndo,
-                  u_int proto, const u_char *pptr, int length)
+                  u_int proto, const u_char *pptr, u_int length)
 {
        const char *typestr;
        u_int code, len;
-       int (*pfunc)(netdissect_options *, const u_char *, int);
-       int x, j;
+       u_int (*pfunc)(netdissect_options *, const u_char *, u_int);
+       u_int x, j;
         const u_char *tptr;
 
         tptr=pptr;
@@ -442,15 +442,26 @@ handle_ctrl_proto(netdissect_options *ndo,
        if (!ndo->ndo_vflag)
                return;
 
-       if (length <= 4)
-               return;    /* there may be a NULL confreq etc. */
-
-       ND_TCHECK2(*tptr, 2);
+       ND_TCHECK_2(tptr);
        len = EXTRACT_BE_U_2(tptr);
        tptr += 2;
 
+       if (len < 4) {
+               ND_PRINT((ndo, "\n\tencoded length %u (< 4))", len));
+               return;
+       }
+
+       if (len > length) {
+               ND_PRINT((ndo, "\n\tencoded length %u (> packet length %u))", len, length));
+               return;
+       }
+       length = len;
+
        ND_PRINT((ndo, "\n\tencoded length %u (=Option(s) length %u)", len, len - 4));
 
+       if (length == 4)
+               return;    /* there may be a NULL confreq etc. */
+
        if (ndo->ndo_vflag > 1)
                print_unknown_data(ndo, pptr - 2, "\n\t", 6);
 
@@ -459,10 +470,10 @@ handle_ctrl_proto(netdissect_options *ndo,
        case CPCODES_VEXT:
                if (length < 11)
                        break;
-               ND_TCHECK2(*tptr, 4);
+               ND_TCHECK_4(tptr);
                ND_PRINT((ndo, "\n\t  Magic-Num 0x%08x", EXTRACT_BE_U_4(tptr)));
                tptr += 4;
-               ND_TCHECK2(*tptr, 3);
+               ND_TCHECK_3(tptr);
                ND_PRINT((ndo, " Vendor: %s (%u)",
                        tok2str(oui_values,"Unknown",EXTRACT_BE_U_3(tptr)),
                        EXTRACT_BE_U_3(tptr)));
@@ -506,7 +517,7 @@ handle_ctrl_proto(netdissect_options *ndo,
                                break;
                        x -= j;
                        tptr += j;
-               } while (x > 0);
+               } while (x != 0);
                break;
 
        case CPCODES_TERM_REQ:
@@ -519,7 +530,7 @@ handle_ctrl_proto(netdissect_options *ndo,
        case CPCODES_PROT_REJ:
                if (length < 6)
                        break;
-               ND_TCHECK2(*tptr, 2);
+               ND_TCHECK_2(tptr);
                ND_PRINT((ndo, "\n\t  Rejected %s Protocol (0x%04x)",
                       tok2str(ppptype2str,"unknown", EXTRACT_BE_U_2(tptr)),
                       EXTRACT_BE_U_2(tptr)));
@@ -534,7 +545,7 @@ handle_ctrl_proto(netdissect_options *ndo,
        case CPCODES_DISC_REQ:
                if (length < 8)
                        break;
-               ND_TCHECK2(*tptr, 4);
+               ND_TCHECK_4(tptr);
                ND_PRINT((ndo, "\n\t  Magic-Num 0x%08x", EXTRACT_BE_U_4(tptr)));
                /* XXX: need to decode Data? - hexdump for now */
                if (len > 8) {
@@ -546,7 +557,7 @@ handle_ctrl_proto(netdissect_options *ndo,
        case CPCODES_ID:
                if (length < 8)
                        break;
-               ND_TCHECK2(*tptr, 4);
+               ND_TCHECK_4(tptr);
                ND_PRINT((ndo, "\n\t  Magic-Num 0x%08x", EXTRACT_BE_U_4(tptr)));
                /* RFC 1661 says this is intended to be human readable */
                if (len > 8) {
@@ -558,9 +569,9 @@ handle_ctrl_proto(netdissect_options *ndo,
        case CPCODES_TIME_REM:
                if (length < 12)
                        break;
-               ND_TCHECK2(*tptr, 4);
+               ND_TCHECK_4(tptr);
                ND_PRINT((ndo, "\n\t  Magic-Num 0x%08x", EXTRACT_BE_U_4(tptr)));
-               ND_TCHECK2(*(tptr + 4), 4);
+               ND_TCHECK_4(tptr + 4);
                ND_PRINT((ndo, ", Seconds-Remaining %us", EXTRACT_BE_U_4(tptr + 4)));
                /* XXX: need to decode Message? */
                break;
@@ -579,17 +590,17 @@ trunc:
 }
 
 /* LCP config options */
-static int
+static u_int
 print_lcp_config_options(netdissect_options *ndo,
-                         const u_char *p, int length)
+                         const u_char *p, u_int length)
 {
-       int len, opt;
+       u_int opt, len;
 
        if (length < 2)
                return 0;
        ND_TCHECK2(*p, 2);
-       len = p[1];
-       opt = p[0];
+       opt = EXTRACT_U_1(p);
+       len = EXTRACT_U_1(p + 1);
        if (length < len)
                return 0;
        if (len < 2) {
@@ -618,12 +629,12 @@ print_lcp_config_options(netdissect_options *ndo,
                        tok2str(oui_values,"Unknown",EXTRACT_BE_U_3(p + 2)),
                        EXTRACT_BE_U_3(p + 2)));
 #if 0
-               ND_TCHECK(p[5]);
-               ND_PRINT((ndo, ", kind: 0x%02x", p[5]));
+               ND_TCHECK_1(p + 5);
+               ND_PRINT((ndo, ", kind: 0x%02x", EXTRACT_U_1(p + 5)));
                ND_PRINT((ndo, ", Value: 0x"));
                for (i = 0; i < len - 6; i++) {
-                       ND_TCHECK(p[6 + i]);
-                       ND_PRINT((ndo, "%02x", p[6 + i]));
+                       ND_TCHECK_1(p + 6 + i);
+                       ND_PRINT((ndo, "%02x", EXTRACT_U_1(p + 6 + i)));
                }
 #endif
                break;
@@ -653,7 +664,7 @@ print_lcp_config_options(netdissect_options *ndo,
 
                switch (EXTRACT_BE_U_2(p + 2)) {
                case PPP_CHAP:
-                       ND_TCHECK(p[4]);
+                       ND_TCHECK_1(p + 4);
                        ND_PRINT((ndo, ", %s", tok2str(authalg_values, "Unknown Auth Alg %u", EXTRACT_U_1(p + 4))));
                        break;
                case PPP_PAP: /* fall through */
@@ -702,10 +713,10 @@ print_lcp_config_options(netdissect_options *ndo,
                        return 0;
                }
                ND_PRINT((ndo, ": "));
-               ND_TCHECK(p[2]);
+               ND_TCHECK_1(p + 2);
                ND_PRINT((ndo, ": Callback Operation %s (%u)",
                        tok2str(ppp_callback_values, "Unknown", EXTRACT_U_1(p + 2)),
-                       p[2]));
+                       EXTRACT_U_1(p + 2)));
                break;
        case LCPOPT_MLMRRU:
                if (len != 4) {
@@ -720,8 +731,8 @@ print_lcp_config_options(netdissect_options *ndo,
                        ND_PRINT((ndo, " (length bogus, should be >= 3)"));
                        return 0;
                }
-               ND_TCHECK(p[2]);
-               switch (p[2]) {         /* class */
+               ND_TCHECK_1(p + 2);
+               switch (EXTRACT_U_1(p + 2)) {           /* class */
                case MEDCLASS_NULL:
                        ND_PRINT((ndo, ": Null"));
                        break;
@@ -751,7 +762,7 @@ print_lcp_config_options(netdissect_options *ndo,
                        ND_PRINT((ndo, ": PSNDN")); /* XXX */
                        break;
                default:
-                       ND_PRINT((ndo, ": Unknown class %u", p[2]));
+                       ND_PRINT((ndo, ": Unknown class %u", EXTRACT_U_1(p + 2)));
                        break;
                }
                break;
@@ -785,12 +796,12 @@ print_lcp_config_options(netdissect_options *ndo,
                 * not going to do so below.
                 */
                if (ndo->ndo_vflag < 2)
-                       print_unknown_data(ndo, &p[2], "\n\t    ", len - 2);
+                       print_unknown_data(ndo, p + 2, "\n\t    ", len - 2);
                break;
        }
 
        if (ndo->ndo_vflag > 1)
-               print_unknown_data(ndo, &p[2], "\n\t    ", len - 2); /* exclude TLV header */
+               print_unknown_data(ndo, p + 2, "\n\t    ", len - 2); /* exclude TLV header */
 
        return len;
 
@@ -808,7 +819,7 @@ static const struct tok ppp_ml_flag_values[] = {
 
 static void
 handle_mlppp(netdissect_options *ndo,
-             const u_char *p, int length)
+             const u_char *p, u_int length)
 {
     if (!ndo->ndo_eflag)
         ND_PRINT((ndo, "MLPPP, "));
@@ -831,35 +842,35 @@ handle_mlppp(netdissect_options *ndo,
 /* CHAP */
 static void
 handle_chap(netdissect_options *ndo,
-            const u_char *p, int length)
+            const u_char *p, u_int length)
 {
        u_int code, len;
-       int val_size, name_size, msg_size;
+       u_int val_size, name_size, msg_size;
        const u_char *p0;
-       int i;
+       u_int i;
 
        p0 = p;
        if (length < 1) {
                ND_PRINT((ndo, "[|chap]"));
                return;
        } else if (length < 4) {
-               ND_TCHECK(*p);
-               ND_PRINT((ndo, "[|chap 0x%02x]", *p));
+               ND_TCHECK_1(p);
+               ND_PRINT((ndo, "[|chap 0x%02x]", EXTRACT_U_1(p)));
                return;
        }
 
-       ND_TCHECK(*p);
-       code = *p;
+       ND_TCHECK_1(p);
+       code = EXTRACT_U_1(p);
        ND_PRINT((ndo, "CHAP, %s (0x%02x)",
                tok2str(chapcode_values,"unknown",code),
                code));
        p++;
 
-       ND_TCHECK(*p);
-       ND_PRINT((ndo, ", id %u", *p));         /* ID */
+       ND_TCHECK_1(p);
+       ND_PRINT((ndo, ", id %u", EXTRACT_U_1(p)));     /* ID */
        p++;
 
-       ND_TCHECK2(*p, 2);
+       ND_TCHECK_2(p);
        len = EXTRACT_BE_U_2(p);
        p += 2;
 
@@ -875,21 +886,21 @@ handle_chap(netdissect_options *ndo,
        case CHAP_RESP:
                if (length - (p - p0) < 1)
                        return;
-               ND_TCHECK(*p);
-               val_size = *p;          /* value size */
+               ND_TCHECK_1(p);
+               val_size = EXTRACT_U_1(p);      /* value size */
                p++;
                if (length - (p - p0) < val_size)
                        return;
                ND_PRINT((ndo, ", Value "));
                for (i = 0; i < val_size; i++) {
-                       ND_TCHECK(*p);
+                       ND_TCHECK_1(p);
                        ND_PRINT((ndo, "%02x", EXTRACT_U_1(p)));
                        p++;
                }
                name_size = len - (p - p0);
                ND_PRINT((ndo, ", Name "));
                for (i = 0; i < name_size; i++) {
-                       ND_TCHECK(*p);
+                       ND_TCHECK_1(p);
                        safeputchar(ndo, EXTRACT_U_1(p));
                        p++;
                }
@@ -899,7 +910,7 @@ handle_chap(netdissect_options *ndo,
                msg_size = len - (p - p0);
                ND_PRINT((ndo, ", Msg "));
                for (i = 0; i< msg_size; i++) {
-                       ND_TCHECK(*p);
+                       ND_TCHECK_1(p);
                        safeputchar(ndo, EXTRACT_U_1(p));
                        p++;
                }
@@ -914,39 +925,39 @@ trunc:
 /* PAP (see RFC 1334) */
 static void
 handle_pap(netdissect_options *ndo,
-           const u_char *p, int length)
+           const u_char *p, u_int length)
 {
        u_int code, len;
-       int peerid_len, passwd_len, msg_len;
+       u_int peerid_len, passwd_len, msg_len;
        const u_char *p0;
-       int i;
+       u_int i;
 
        p0 = p;
        if (length < 1) {
                ND_PRINT((ndo, "[|pap]"));
                return;
        } else if (length < 4) {
-               ND_TCHECK(*p);
-               ND_PRINT((ndo, "[|pap 0x%02x]", *p));
+               ND_TCHECK_1(p);
+               ND_PRINT((ndo, "[|pap 0x%02x]", EXTRACT_U_1(p)));
                return;
        }
 
-       ND_TCHECK(*p);
-       code = *p;
+       ND_TCHECK_1(p);
+       code = EXTRACT_U_1(p);
        ND_PRINT((ndo, "PAP, %s (0x%02x)",
                  tok2str(papcode_values, "unknown", code),
                  code));
        p++;
 
-       ND_TCHECK(*p);
-       ND_PRINT((ndo, ", id %u", *p));         /* ID */
+       ND_TCHECK_1(p);
+       ND_PRINT((ndo, ", id %u", EXTRACT_U_1(p)));     /* ID */
        p++;
 
-       ND_TCHECK2(*p, 2);
+       ND_TCHECK_2(p);
        len = EXTRACT_BE_U_2(p);
        p += 2;
 
-       if ((int)len > length) {
+       if (len > length) {
                ND_PRINT((ndo, ", length %u > packet size", len));
                return;
        }
@@ -963,28 +974,28 @@ handle_pap(netdissect_options *ndo,
                        goto trunc;
                if (length - (p - p0) < 1)
                        return;
-               ND_TCHECK(*p);
-               peerid_len = *p;        /* Peer-ID Length */
+               ND_TCHECK_1(p);
+               peerid_len = EXTRACT_U_1(p);    /* Peer-ID Length */
                p++;
                if (length - (p - p0) < peerid_len)
                        return;
                ND_PRINT((ndo, ", Peer "));
                for (i = 0; i < peerid_len; i++) {
-                       ND_TCHECK(*p);
+                       ND_TCHECK_1(p);
                        safeputchar(ndo, EXTRACT_U_1(p));
                        p++;
                }
 
                if (length - (p - p0) < 1)
                        return;
-               ND_TCHECK(*p);
-               passwd_len = *p;        /* Password Length */
+               ND_TCHECK_1(p);
+               passwd_len = EXTRACT_U_1(p);    /* Password Length */
                p++;
                if (length - (p - p0) < passwd_len)
                        return;
                ND_PRINT((ndo, ", Name "));
                for (i = 0; i < passwd_len; i++) {
-                       ND_TCHECK(*p);
+                       ND_TCHECK_1(p);
                        safeputchar(ndo, EXTRACT_U_1(p));
                        p++;
                }
@@ -1000,14 +1011,14 @@ handle_pap(netdissect_options *ndo,
                        goto trunc;
                if (length - (p - p0) < 1)
                        return;
-               ND_TCHECK(*p);
-               msg_len = *p;           /* Msg-Length */
+               ND_TCHECK_1(p);
+               msg_len = EXTRACT_U_1(p);       /* Msg-Length */
                p++;
                if (length - (p - p0) < msg_len)
                        return;
                ND_PRINT((ndo, ", Msg "));
                for (i = 0; i< msg_len; i++) {
-                       ND_TCHECK(*p);
+                       ND_TCHECK_1(p);
                        safeputchar(ndo, EXTRACT_U_1(p));
                        p++;
                }
@@ -1022,25 +1033,25 @@ trunc:
 /* BAP */
 static void
 handle_bap(netdissect_options *ndo _U_,
-           const u_char *p _U_, int length _U_)
+           const u_char *p _U_, u_int length _U_)
 {
        /* XXX: to be supported!! */
 }
 
 
 /* IPCP config options */
-static int
+static u_int
 print_ipcp_config_options(netdissect_options *ndo,
-                          const u_char *p, int length)
+                          const u_char *p, u_int length)
 {
-       int len, opt;
+       u_int opt, len;
         u_int compproto, ipcomp_subopttotallen, ipcomp_subopt, ipcomp_suboptlen;
 
        if (length < 2)
                return 0;
        ND_TCHECK2(*p, 2);
-       len = p[1];
-       opt = p[0];
+       opt = EXTRACT_U_1(p);
+       len = EXTRACT_U_1(p + 1);
        if (length < len)
                return 0;
        if (len < 2) {
@@ -1108,7 +1119,7 @@ print_ipcp_config_options(netdissect_options *ndo,
 
                                 while (ipcomp_subopttotallen >= 2) {
                                         ND_TCHECK2(*p, 2);
-                                        ipcomp_subopt = *p;
+                                        ipcomp_subopt = EXTRACT_U_1(p);
                                         ipcomp_suboptlen = EXTRACT_U_1(p + 1);
 
                                         /* sanity check */
@@ -1153,11 +1164,11 @@ print_ipcp_config_options(netdissect_options *ndo,
                 * not going to do so below.
                 */
                if (ndo->ndo_vflag < 2)
-                       print_unknown_data(ndo, &p[2], "\n\t    ", len - 2);
+                       print_unknown_data(ndo, p + 2, "\n\t    ", len - 2);
                break;
        }
        if (ndo->ndo_vflag > 1)
-               print_unknown_data(ndo, &p[2], "\n\t    ", len - 2); /* exclude TLV header */
+               print_unknown_data(ndo, p + 2, "\n\t    ", len - 2); /* exclude TLV header */
        return len;
 
 trunc:
@@ -1166,17 +1177,17 @@ trunc:
 }
 
 /* IP6CP config options */
-static int
+static u_int
 print_ip6cp_config_options(netdissect_options *ndo,
-                           const u_char *p, int length)
+                           const u_char *p, u_int length)
 {
-       int len, opt;
+       u_int opt, len;
 
        if (length < 2)
                return 0;
        ND_TCHECK2(*p, 2);
-       len = p[1];
-       opt = p[0];
+       opt = EXTRACT_U_1(p);
+       len = EXTRACT_U_1(p + 1);
        if (length < len)
                return 0;
        if (len < 2) {
@@ -1211,11 +1222,11 @@ print_ip6cp_config_options(netdissect_options *ndo,
                 * not going to do so below.
                 */
                if (ndo->ndo_vflag < 2)
-                       print_unknown_data(ndo, &p[2], "\n\t    ", len - 2);
+                       print_unknown_data(ndo, p + 2, "\n\t    ", len - 2);
                break;
        }
        if (ndo->ndo_vflag > 1)
-               print_unknown_data(ndo, &p[2], "\n\t    ", len - 2); /* exclude TLV header */
+               print_unknown_data(ndo, p + 2, "\n\t    ", len - 2); /* exclude TLV header */
 
        return len;
 
@@ -1226,17 +1237,17 @@ trunc:
 
 
 /* CCP config options */
-static int
+static u_int
 print_ccp_config_options(netdissect_options *ndo,
-                         const u_char *p, int length)
+                         const u_char *p, u_int length)
 {
-       int len, opt;
+       u_int opt, len;
 
        if (length < 2)
                return 0;
        ND_TCHECK2(*p, 2);
-       len = p[1];
-       opt = p[0];
+       opt = EXTRACT_U_1(p);
+       len = EXTRACT_U_1(p + 1);
        if (length < len)
                return 0;
        if (len < 2) {
@@ -1258,31 +1269,35 @@ print_ccp_config_options(netdissect_options *ndo,
                        ND_PRINT((ndo, " (length bogus, should be >= 3)"));
                        return len;
                }
-               ND_TCHECK(p[2]);
+               ND_TCHECK_1(p + 2);
                ND_PRINT((ndo, ": Version: %u, Dictionary Bits: %u",
-                       p[2] >> 5, p[2] & 0x1f));
+                       EXTRACT_U_1(p + 2) >> 5,
+                       EXTRACT_U_1(p + 2) & 0x1f));
                break;
        case CCPOPT_MVRCA:
                if (len < 4) {
                        ND_PRINT((ndo, " (length bogus, should be >= 4)"));
                        return len;
                }
-               ND_TCHECK(p[3]);
+               ND_TCHECK_1(p + 3);
                ND_PRINT((ndo, ": Features: %u, PxP: %s, History: %u, #CTX-ID: %u",
-                               (p[2] & 0xc0) >> 6,
-                               (p[2] & 0x20) ? "Enabled" : "Disabled",
-                               p[2] & 0x1f, p[3]));
+                               (EXTRACT_U_1(p + 2) & 0xc0) >> 6,
+                               (EXTRACT_U_1(p + 2) & 0x20) ? "Enabled" : "Disabled",
+                               EXTRACT_U_1(p + 2) & 0x1f,
+                               EXTRACT_U_1(p + 3)));
                break;
        case CCPOPT_DEFLATE:
                if (len < 4) {
                        ND_PRINT((ndo, " (length bogus, should be >= 4)"));
                        return len;
                }
-               ND_TCHECK(p[3]);
+               ND_TCHECK_1(p + 3);
                ND_PRINT((ndo, ": Window: %uK, Method: %s (0x%x), MBZ: %u, CHK: %u",
-                       (p[2] & 0xf0) >> 4,
-                       ((p[2] & 0x0f) == 8) ? "zlib" : "unknown",
-                       p[2] & 0x0f, (p[3] & 0xfc) >> 2, p[3] & 0x03));
+                       (EXTRACT_U_1(p + 2) & 0xf0) >> 4,
+                       ((EXTRACT_U_1(p + 2) & 0x0f) == 8) ? "zlib" : "unknown",
+                       EXTRACT_U_1(p + 2) & 0x0f,
+                       (EXTRACT_U_1(p + 3) & 0xfc) >> 2,
+                       EXTRACT_U_1(p + 3) & 0x03));
                break;
 
 /* XXX: to be supported */
@@ -1307,11 +1322,11 @@ print_ccp_config_options(netdissect_options *ndo,
                 * not going to do so below.
                 */
                if (ndo->ndo_vflag < 2)
-                       print_unknown_data(ndo, &p[2], "\n\t    ", len - 2);
+                       print_unknown_data(ndo, p + 2, "\n\t    ", len - 2);
                break;
        }
        if (ndo->ndo_vflag > 1)
-               print_unknown_data(ndo, &p[2], "\n\t    ", len - 2); /* exclude TLV header */
+               print_unknown_data(ndo, p + 2, "\n\t    ", len - 2); /* exclude TLV header */
 
        return len;
 
@@ -1321,17 +1336,17 @@ trunc:
 }
 
 /* BACP config options */
-static int
+static u_int
 print_bacp_config_options(netdissect_options *ndo,
-                          const u_char *p, int length)
+                          const u_char *p, u_int length)
 {
-       int len, opt;
+       u_int opt, len;
 
        if (length < 2)
                return 0;
        ND_TCHECK2(*p, 2);
-       len = p[1];
-       opt = p[0];
+       opt = EXTRACT_U_1(p);
+       len = EXTRACT_U_1(p + 1);
        if (length < len)
                return 0;
        if (len < 2) {
@@ -1362,11 +1377,11 @@ print_bacp_config_options(netdissect_options *ndo,
                 * not going to do so below.
                 */
                if (ndo->ndo_vflag < 2)
-                       print_unknown_data(ndo, &p[2], "\n\t    ", len - 2);
+                       print_unknown_data(ndo, p + 2, "\n\t    ", len - 2);
                break;
        }
        if (ndo->ndo_vflag > 1)
-               print_unknown_data(ndo, &p[2], "\n\t    ", len - 2); /* exclude TLV header */
+               print_unknown_data(ndo, p + 2, "\n\t    ", len - 2); /* exclude TLV header */
 
        return len;
 
@@ -1377,14 +1392,14 @@ trunc:
 
 static void
 ppp_hdlc(netdissect_options *ndo,
-         const u_char *p, int length)
+         const u_char *p, u_int length)
 {
        u_char *b, *t, c;
        const u_char *s;
-       int i, proto;
+       u_int i, proto;
        const void *se;
 
-        if (length <= 0)
+        if (length == 0)
                 return;
 
        b = (u_char *)malloc(length);
@@ -1396,11 +1411,11 @@ ppp_hdlc(netdissect_options *ndo,
         * Do this so that we dont overwrite the original packet
         * contents.
         */
-       for (s = p, t = b, i = length; i > 0 && ND_TTEST(*s); i--) {
+       for (s = p, t = b, i = length; i != 0 && ND_TTEST(*s); i--) {
                c = EXTRACT_U_1(s);
                s++;
                if (c == 0x7d) {
-                       if (i <= 1 || !ND_TTEST(*s))
+                       if (i <= 1 || !ND_TTEST_1(s))
                                break;
                        i--;
                        c = EXTRACT_U_1(s) ^ 0x20;
@@ -1409,6 +1424,9 @@ ppp_hdlc(netdissect_options *ndo,
                *t++ = c;
        }
 
+       /*
+        * Change the end pointer, so bounds checks work.
+        */
        se = ndo->ndo_snapend;
        ndo->ndo_snapend = t;
        length = t - b;
@@ -1416,7 +1434,7 @@ ppp_hdlc(netdissect_options *ndo,
         /* now lets guess about the payload codepoint format */
         if (length < 1)
                 goto trunc;
-        proto = *b; /* start with a one-octet codepoint guess */
+        proto = EXTRACT_U_1(b); /* start with a one-octet codepoint guess */
 
         switch (proto) {
         case PPP_IP:
@@ -1460,7 +1478,7 @@ trunc:
 /* PPP */
 static void
 handle_ppp(netdissect_options *ndo,
-           u_int proto, const u_char *p, int length)
+           u_int proto, const u_char *p, u_int length)
 {
        if ((proto & 0xff00) == 0x7e00) { /* is this an escape code ? */
                ppp_hdlc(ndo, p - 1, length);
@@ -1534,7 +1552,7 @@ ppp_print(netdissect_options *ndo,
         */
        if (length < 2)
                goto trunc;
-       ND_TCHECK2(*p, 2);
+       ND_TCHECK_2(p);
         ppp_header = EXTRACT_BE_U_2(p);
 
         switch(ppp_header) {
@@ -1562,14 +1580,14 @@ ppp_print(netdissect_options *ndo,
 
        if (length < 2)
                goto trunc;
-       ND_TCHECK(*p);
-       if (*p % 2) {
-               proto = *p;             /* PFC is used */
+       ND_TCHECK_1(p);
+       if (EXTRACT_U_1(p) % 2) {
+               proto = EXTRACT_U_1(p); /* PFC is used */
                p++;
                length--;
                hdr_len++;
        } else {
-               ND_TCHECK2(*p, 2);
+               ND_TCHECK_2(p);
                proto = EXTRACT_BE_U_2(p);
                p += 2;
                length -= 2;
@@ -1641,7 +1659,8 @@ ppp_if_print(netdissect_options *ndo,
         * BSD/OS, is?)
         */
        if (ndo->ndo_eflag)
-               ND_PRINT((ndo, "%c %4d %02x ", p[0] ? 'O' : 'I', length, p[1]));
+               ND_PRINT((ndo, "%c %4d %02x ", EXTRACT_U_1(p) ? 'O' : 'I',
+                   length, EXTRACT_U_1(p + 1)));
 #endif
 
        ppp_print(ndo, p, length);
@@ -1672,16 +1691,17 @@ ppp_hdlc_if_print(netdissect_options *ndo,
                return (caplen);
        }
 
-       switch (p[0]) {
+       switch (EXTRACT_U_1(p)) {
 
        case PPP_ADDRESS:
-               if (caplen < 4) {
+               if (caplen < 4 || length < 4) {
                        ND_PRINT((ndo, "[|ppp]"));
                        return (caplen);
                }
 
                if (ndo->ndo_eflag)
-                       ND_PRINT((ndo, "%02x %02x %d ", p[0], p[1], length));
+                       ND_PRINT((ndo, "%02x %02x %u ", EXTRACT_U_1(p),
+                           EXTRACT_U_1(p + 1), length));
                p += 2;
                length -= 2;
                hdrlen += 2;
@@ -1706,7 +1726,8 @@ ppp_hdlc_if_print(netdissect_options *ndo,
                }
 
                if (ndo->ndo_eflag)
-                       ND_PRINT((ndo, "%02x %02x %d ", p[0], p[1], length));
+                       ND_PRINT((ndo, "%02x %02x %d ", EXTRACT_U_1(p),
+                           EXTRACT_U_1(p + 1), length));
                p += 2;
                hdrlen += 2;
 
@@ -1715,7 +1736,8 @@ ppp_hdlc_if_print(netdissect_options *ndo,
                 * the next two octets as an Ethernet type; does that
                 * ever happen?
                 */
-               ND_PRINT((ndo, "unknown addr %02x; ctrl %02x", p[0], p[1]));
+               ND_PRINT((ndo, "unknown addr %02x; ctrl %02x", EXTRACT_U_1(p),
+                   EXTRACT_U_1(p + 1)));
                break;
        }
 
@@ -1729,13 +1751,14 @@ u_int
 ppp_bsdos_if_print(netdissect_options *ndo _U_,
                    const struct pcap_pkthdr *h _U_, register const u_char *p _U_)
 {
-       register int hdrlength;
+       register u_int hdrlength;
 #ifdef __bsdi__
        register u_int length = h->len;
        register u_int caplen = h->caplen;
        uint16_t ptype;
+       uint8_t llhl;
        const u_char *q;
-       int i;
+       u_int i;
 
        if (caplen < PPP_BSDI_HDRLEN) {
                ND_PRINT((ndo, "[|ppp]"));
@@ -1745,9 +1768,11 @@ ppp_bsdos_if_print(netdissect_options *ndo _U_,
        hdrlength = 0;
 
 #if 0
-       if (p[0] == PPP_ADDRESS && p[1] == PPP_CONTROL) {
+       if (EXTRACT_U_1(p) == PPP_ADDRESS &&
+           EXTRACT_U_1(p + 1) == PPP_CONTROL) {
                if (ndo->ndo_eflag)
-                       ND_PRINT((ndo, "%02x %02x ", p[0], p[1]));
+                       ND_PRINT((ndo, "%02x %02x ", EXTRACT_U_1(p),
+                           EXTRACT_U_1(p + 1)));
                p += 2;
                hdrlength = 2;
        }
@@ -1755,9 +1780,9 @@ ppp_bsdos_if_print(netdissect_options *ndo _U_,
        if (ndo->ndo_eflag)
                ND_PRINT((ndo, "%d ", length));
        /* Retrieve the protocol type */
-       if (*p & 01) {
+       if (EXTRACT_U_1(p) & 01) {
                /* Compressed protocol field */
-               ptype = *p;
+               ptype = EXTRACT_U_1(p);
                if (ndo->ndo_eflag)
                        ND_PRINT((ndo, "%02x ", ptype));
                p++;
@@ -1773,8 +1798,9 @@ ppp_bsdos_if_print(netdissect_options *ndo _U_,
 #else
        ptype = 0;      /*XXX*/
        if (ndo->ndo_eflag)
-               ND_PRINT((ndo, "%c ", p[SLC_DIR] ? 'O' : 'I'));
-       if (p[SLC_LLHL]) {
+               ND_PRINT((ndo, "%c ", EXTRACT_U_1(p + SLC_DIR) ? 'O' : 'I'));
+       llhl = EXTRACT_U_1(p + SLC_LLHL);
+       if (llhl) {
                /* link level header */
                struct ppp_header *ph;
 
@@ -1783,7 +1809,8 @@ ppp_bsdos_if_print(netdissect_options *ndo _U_,
                if (ph->phdr_addr == PPP_ADDRESS
                 && ph->phdr_ctl == PPP_CONTROL) {
                        if (ndo->ndo_eflag)
-                               ND_PRINT((ndo, "%02x %02x ", q[0], q[1]));
+                               ND_PRINT((ndo, "%02x %02x ", EXTRACT_U_1(q),
+                                   EXTRACT_U_1(q + 1)));
                        ptype = EXTRACT_BE_U_2(&ph->phdr_type);
                        if (ndo->ndo_eflag && (ptype == PPP_VJC || ptype == PPP_VJNC)) {
                                ND_PRINT((ndo, "%s ", tok2str(ppptype2str,
@@ -1792,16 +1819,16 @@ ppp_bsdos_if_print(netdissect_options *ndo _U_,
                } else {
                        if (ndo->ndo_eflag) {
                                ND_PRINT((ndo, "LLH=["));
-                               for (i = 0; i < p[SLC_LLHL]; i++)
-                                       ND_PRINT((ndo, "%02x", q[i]));
+                               for (i = 0; i < llhl; i++)
+                                       ND_PRINT((ndo, "%02x", EXTRACT_U_1(q + i)));
                                ND_PRINT((ndo, "] "));
                        }
                }
        }
        if (ndo->ndo_eflag)
                ND_PRINT((ndo, "%d ", length));
-       if (p[SLC_CHL]) {
-               q = p + SLC_BPFHDRLEN + p[SLC_LLHL];
+       if (EXTRACT_U_1(p + SLC_CHL)) {
+               q = p + SLC_BPFHDRLEN + llhl;
 
                switch (ptype) {
                case PPP_VJC:
@@ -1841,8 +1868,9 @@ ppp_bsdos_if_print(netdissect_options *ndo _U_,
                default:
                        if (ndo->ndo_eflag) {
                                ND_PRINT((ndo, "CH=["));
-                               for (i = 0; i < p[SLC_LLHL]; i++)
-                                       ND_PRINT((ndo, "%02x", q[i]));
+                               for (i = 0; i < llhl; i++)
+                                       ND_PRINT((ndo, "%02x",
+                                           EXTRACT_U_1(q + i)));
                                ND_PRINT((ndo, "] "));
                        }
                        break;