Don't decrement an unsigned value past zero.

That also means we do one less decrement, so it's not as if testing
i-- rather than testing i and separately decrementing it is an
optimization.

Fix some types to unsigned while we're at it - and do the above change
for them, too.

diff --git a/print-snmp.c b/print-snmp.c
index 91136796b2a8b713f0cad749312178cb1a1acb54..048e6989a7ece5e6830b4304a51b517a6fd3287b 100644 (file)
--- a/print-snmp.c
+++ b/print-snmp.c
@@ -421,7 +421,7 @@ asn1_parse(netdissect_options *ndo,
            const u_char *p, u_int len, struct be *elem)
 {
        u_char form, class, id;
-       int i, hdr;
+       u_int i, hdr;
 
        elem->asnlen = 0;
        elem->type = BE_ANY;
@@ -545,7 +545,7 @@ asn1_parse(netdissect_options *ndo,
                                }
                                if (EXTRACT_U_1(p) & ASN_BIT8)  /* negative */
                                        data = -1;
-                               for (i = elem->asnlen; i-- > 0; p++)
+                               for (i = elem->asnlen; i != 0; p++, i--)
                                        data = (data << ASN_SHIFT8) | EXTRACT_U_1(p);
                                elem->data.integer = data;
                                break;
@@ -582,7 +582,7 @@ asn1_parse(netdissect_options *ndo,
                                uint32_t data;
                                elem->type = BE_UNS;
                                data = 0;
-                               for (i = elem->asnlen; i-- > 0; p++)
+                               for (i = elem->asnlen; i != 0; p++, i--)
                                        data = (data << 8) + EXTRACT_U_1(p);
                                elem->data.uns = data;
                                break;
@@ -592,7 +592,7 @@ asn1_parse(netdissect_options *ndo,
                                uint64_t data64;
                                elem->type = BE_UNS64;
                                data64 = 0;
-                               for (i = elem->asnlen; i-- > 0; p++)
+                               for (i = elem->asnlen; i != 0; p++, i--)
                                        data64 = (data64 << 8) + EXTRACT_U_1(p);
                                elem->data.uns64 = data64;
                                break;
@@ -681,7 +681,7 @@ asn1_print_octets(netdissect_options *ndo, struct be *elem)
        uint32_t i;
 
        ND_TCHECK_LEN(p, asnlen);
-       for (i = asnlen; i-- > 0; p++)
+       for (i = asnlen; i != 0; p++, i--)
                ND_PRINT("_%.2x", EXTRACT_U_1(p));
        return 0;
 
@@ -700,7 +700,7 @@ asn1_print_string(netdissect_options *ndo, struct be *elem)
 
        p = elem->data.str;
        ND_TCHECK_LEN(p, asnlen);
-       for (i = asnlen; printable && i-- > 0; p++)
+       for (i = asnlen; printable && i != 0; p++, i--)
                printable = ND_ISPRINT(EXTRACT_U_1(p));
        p = elem->data.str;
        if (printable) {
@@ -711,7 +711,7 @@ asn1_print_string(netdissect_options *ndo, struct be *elem)
                }
                ND_PRINT("\"");
        } else {
-               for (i = asnlen; i-- > 0; p++) {
+               for (i = asnlen; i != 0; p++, i--) {
                        ND_PRINT(first ? "%.2x" : "_%.2x", EXTRACT_U_1(p));
                        first = 0;
                }
@@ -769,7 +769,7 @@ asn1_print(netdissect_options *ndo,
                        }
                }
 
-               for (; i-- > 0; p++) {
+               for (; i != 0; p++, i--) {
                        ND_TCHECK_1(p);
                        o = (o << ASN_SHIFT7) + (EXTRACT_U_1(p) & ~ASN_BIT8);
                        if (EXTRACT_U_1(p) & ASN_LONGLEN)
@@ -824,7 +824,7 @@ asn1_print(netdissect_options *ndo,
                        ND_PRINT("[inetaddr len!=%d]", ASNLEN_INETADDR);
                p = (const u_char *)elem->data.raw;
                ND_TCHECK_LEN(p, asnlen);
-               for (i = asnlen; i-- != 0; p++) {
+               for (i = asnlen; i != 0; p++, i--) {
                        ND_PRINT((i == asnlen-1) ? "%u" : ".%u", EXTRACT_U_1(p));
                }
                break;
@@ -918,10 +918,11 @@ smi_decode_oid(netdissect_options *ndo,
 {
        const u_char *p = (const u_char *)elem->data.raw;
        uint32_t asnlen = elem->asnlen;
-       int o = 0, first = -1, i = asnlen;
+       uint32_t i = asnlen;
+       int o = 0, first = -1;
        unsigned int firstval;
 
-       for (*oidlen = 0; i-- > 0; p++) {
+       for (*oidlen = 0; i != 0; p++, i--) {
                ND_TCHECK_1(p);
                o = (o << ASN_SHIFT7) + (EXTRACT_U_1(p) & ~ASN_BIT8);
                if (EXTRACT_U_1(p) & ASN_LONGLEN)