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Account for VLAN header in pcap packets if needed.

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This commit is contained in:
dmiller
2025-04-10 19:00:50 +00:00
parent 210d6c0847
commit 5f6bc69983
4 changed files with 32 additions and 17 deletions
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24
libnetutil/netutil.cc
View File

@@ -4202,9 +4202,22 @@ int read_reply_pcap(pcap_t *pd, long to_usec,
netutil_fatal("Error from pcap_next_ex: %s\n", pcap_geterr(pd)); netutil_fatal("Error from pcap_next_ex: %s\n", pcap_geterr(pd));
} }
if (pcap_status == 1 && *p != NULL && accept_callback(*p, *head, *datalink, *offset)) { if (pcap_status == 1 && *p != NULL) {
/* Offset may be different in the case of 802.1q */
if (*datalink == DLT_EN10MB
&& (*head)->caplen >= sizeof(struct eth_hdr)
&& 0 == memcmp((*p) + offsetof(struct eth_hdr, eth_type), "\x81\x00", 2)) {
*offset += 4;
}
if (accept_callback(*p, *head, *datalink, *offset)) {
break; break;
} else if (pcap_status == 0 || *p == NULL) { } else {
/* We'll be a bit patient if we're getting actual packets back, but
not indefinitely so */
if (badcounter++ > 50)
timedout = 1;
}
} else {
/* Should we timeout? */ /* Should we timeout? */
if (to_usec == 0) { if (to_usec == 0) {
timedout = 1; timedout = 1;
@@ -4214,11 +4227,6 @@ int read_reply_pcap(pcap_t *pd, long to_usec,
timedout = 1; timedout = 1;
} }
} }
} else {
/* We'll be a bit patient if we're getting actual packets back, but
not indefinitely so */
if (badcounter++ > 50)
timedout = 1;
} }
} while (!timedout); } while (!timedout);
@@ -4258,7 +4266,7 @@ static bool accept_arp(const unsigned char *p, const struct pcap_pkthdr *head,
return false; return false;
if (datalink == DLT_EN10MB) { if (datalink == DLT_EN10MB) {
return ntohs(*((u16 *) (p + 12))) == ETH_TYPE_ARP; return ntohs(*((u16 *) (p + offset - 2))) == ETH_TYPE_ARP;
} else if (datalink == DLT_LINUX_SLL) { } else if (datalink == DLT_LINUX_SLL) {
return ntohs(*((u16 *) (p + 2))) == ARPHRD_ETHER && /* sll_hatype */ return ntohs(*((u16 *) (p + 2))) == ARPHRD_ETHER && /* sll_hatype */
ntohs(*((u16 *) (p + 4))) == 6 && /* sll_halen */ ntohs(*((u16 *) (p + 4))) == 6 && /* sll_halen */

10
nping/ProbeMode.cc
View File

@@ -1565,7 +1565,7 @@ void ProbeMode::probe_nping_event_handler(nsock_pool nsp, nsock_event nse, void
const unsigned char *link=NULL; const unsigned char *link=NULL;
size_t linklen=0; size_t linklen=0;
size_t packetlen=0; size_t packetlen=0;
u16 *ethtype=NULL; u16 ethtype=0;
u8 buffer[512+1]; u8 buffer[512+1];
size_t link_offset=0; size_t link_offset=0;
static struct timeval pcaptime; static struct timeval pcaptime;
@@ -1632,9 +1632,9 @@ void ProbeMode::probe_nping_event_handler(nsock_pool nsp, nsock_event nse, void
/* If we are on a Ethernet network, extract the next packet protocol /* If we are on a Ethernet network, extract the next packet protocol
* from the Ethernet frame. */ * from the Ethernet frame. */
if( nsock_iod_linktype(nsi) == DLT_EN10MB ){ if( nsock_iod_linktype(nsi) == DLT_EN10MB ){
ethtype=(u16*)(link+12); ethtype=*(u16*)(link + linklen - 2);
*ethtype=ntohs(*ethtype); ethtype=ntohs(ethtype);
switch(*ethtype){ switch(ethtype){
case ETHTYPE_IPV4: case ETHTYPE_IPV4:
case ETHTYPE_IPV6: case ETHTYPE_IPV6:
ip=true; ip=true;
@@ -1644,7 +1644,7 @@ void ProbeMode::probe_nping_event_handler(nsock_pool nsp, nsock_event nse, void
ip=false; ip=false;
break; break;
default: default:
nping_warning(QT_1, "RCVD (%.4fs) Unsupported protocol (Ethernet type %02X)", o.stats.elapsedRuntime(t), *ethtype); nping_warning(QT_1, "RCVD (%.4fs) Unsupported protocol (Ethernet type %02X)", o.stats.elapsedRuntime(t), ethtype);
print_hexdump(VB_3, packet, packetlen); print_hexdump(VB_3, packet, packetlen);
return; return;
break; break;

11
nsock/src/nsock_pcap.c
View File

@@ -476,8 +476,15 @@ void nse_readpcap(nsock_event nsev, const unsigned char **l2_data, size_t *l2_le
return; return;
} }
l2l = MIN(mp->l3_offset, n->caplen); l2l = mp->l3_offset;
l3l = MAX(0, n->caplen-mp->l3_offset); if (mp->datalink == DLT_EN10MB
&& n->caplen >= sizeof(struct eth_hdr)
&& 0 == memcmp(n->packet + offsetof(struct eth_hdr, eth_type), "\x81\x00", 2))
l2l += 4;
}
if (l2l > n->caplen)
l2l = n->caplen;
l3l = MAX(0, n->caplen - l2l);
if (l2_data) if (l2_data)
*l2_data = n->packet; *l2_data = n->packet;

2
tcpip.cc
View File

@@ -1610,7 +1610,7 @@ int setTargetMACIfAvailable(Target *target, struct link_header *linkhdr,
if (!linkhdr || !target || !src) if (!linkhdr || !target || !src)
return 1; return 1;
if (linkhdr->datalinktype != DLT_EN10MB || linkhdr->headerlen != 14) if (linkhdr->datalinktype != DLT_EN10MB || linkhdr->headerlen < 14)
return 2; return 2;
if (!overwrite && target->MACAddress()) if (!overwrite && target->MACAddress())