ICMP: Fix printing the Interface Name Sub-Object

RFC 5837 - 4.3.  Interface Name Sub-Object
"The Interface Name Sub-Object MUST have a length that is a multiple
 of 4 octets and MUST NOT exceed 64 octets.

 The Length field represents the length of the Interface Name Sub-
 Object, including the length and the interface name in octets."

The length of the interface name to print is: (Length field) - 1.
The offset is only: Length field

Add sanity checks: Multiple of 4 octets, <= 64 octets.

Fix the icmp-rfc5837.pcap test.
The interface name length in octets is 63, thus the length field must be 64.
Update also the ICMP Multi-Part Extensions checksum.

Keep an invalid length field in icmp-cksum-oobr-2.pcap.

Update the output of two tests accordingly.

diff --git a/print-icmp.c b/print-icmp.c
index 4e66a3cff96c8928c47cfa4475720ddde70fee09..74f327fc251f690cc3a6b414150daabdfca005b2 100644 (file)
--- a/print-icmp.c
+++ b/print-icmp.c
@@ -853,11 +853,23 @@ icmp_print(netdissect_options *ndo, const u_char *bp, u_int plen, const u_char *
 
                         ifname_subobj = (const struct icmp_interface_identification_ifname_subobject_t *) offset;
                         inft_name_length_field = GET_U_1(ifname_subobj->length);
-                        ND_PRINT("\n\t\t Interface Name, length %u: %.*s",
-                                 inft_name_length_field,
-                                 inft_name_length_field,
+                        ND_PRINT("\n\t\t Interface Name");
+                        if (inft_name_length_field % 4 != 0) {
+                            ND_PRINT(" [length %u != N x 4]", inft_name_length_field);
+                            nd_print_invalid(ndo);
+                            offset += inft_name_length_field;
+                            break;
+                        }
+                        if (inft_name_length_field > 64) {
+                            ND_PRINT(" [length %u > 64]", inft_name_length_field);
+                            nd_print_invalid(ndo);
+                            offset += inft_name_length_field;
+                            break;
+                        }
+                        ND_PRINT(", length %u", inft_name_length_field);
+                        ND_PRINT(": %.*s", inft_name_length_field - 1,
                                  ifname_subobj->if_name);
-                        offset += 1 + inft_name_length_field;
+                        offset += inft_name_length_field;
                     }
                     if (mtu_flag) {
                         ND_PRINT("\n\t\t MTU: %u", GET_BE_U_4(offset));

diff --git a/tests/icmp-cksum-oobr-2.out b/tests/icmp-cksum-oobr-2.out
index fd2a22eba514cba79751862bc7f71a016a6c15ba..79089e5d0be130680e5ac4edf354364700f284a6 100644 (file)
--- a/tests/icmp-cksum-oobr-2.out
+++ b/tests/icmp-cksum-oobr-2.out
@@ -7,4 +7,4 @@
                 This object describes the IP interface upon which a datagram arrived
                 Interface Index: 15
                 IP Address sub-object: 10.10.10.10
-                Interface Name, length 63: This-is-the-name-of-the-Interface-that-we-are-looking-for-[:-)] [|icmp]
+                Interface Name [length 63 != N x 4] (invalid) [|icmp]

diff --git a/tests/icmp-rfc5837.out b/tests/icmp-rfc5837.out
index e5342bc513a8688e2a0922652cab4871c01a9552..a65f3b7bc2f775db04d0934c96adf033def1e8cc 100644 (file)
--- a/tests/icmp-rfc5837.out
+++ b/tests/icmp-rfc5837.out
@@ -2,9 +2,9 @@
     10.4.0.2 > 12.4.4.4: ICMP time exceeded in-transit, length 220
        IP (tos 0x0, ttl 1, id 42321, offset 0, flags [none], proto UDP (17), length 40)
     12.4.4.4.42315 > 12.1.1.1.33440: UDP, length 12
-       ICMP Multi-Part extension v2, checksum 0x256c (correct), length 84
+       ICMP Multi-Part extension v2, checksum 0x246c (correct), length 84
          Interface Identification Object (2), Class-Type: 14, length 80
                 This object describes the IP interface upon which a datagram arrived
                 Interface Index: 15
                 IP Address sub-object: 10.10.10.10
-                Interface Name, length 63: This-is-the-name-of-the-Interface-that-we-are-looking-for-[:-)]
+                Interface Name, length 64: This-is-the-name-of-the-Interface-that-we-are-looking-for-[:-)]

diff --git a/tests/icmp-rfc5837.pcap b/tests/icmp-rfc5837.pcap
index 5daa8e5ac782954384f1ecb5bced7e6c0279a4fb..c600bf8326e41837133a27a724065eb082720b37 100644 (file)
Binary files a/tests/icmp-rfc5837.pcap and b/tests/icmp-rfc5837.pcap differ