Skip to content

Commit

Permalink
Fix dhcpmon bugs (#9008)
Browse files Browse the repository at this point in the history 
* Exclude incrementing on aggregate device if packet received on mgmt interface

* Fix DHCPv6 header offset calculation
  • Loading branch information
@kellyyeh
kellyyeh authored Oct 19, 2021
1 parent 459d3d1 commit 14aca81
Show file tree
Hide file tree
Showing 3 changed files with 51 additions and 8 deletions.
45 changes: 37 additions & 8 deletions src/dhcpmon/src/dhcp_device.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -121,6 +121,8 @@ static struct sock_fprog dhcp_sock_bfp = {
*/
static dhcp_device_context_t aggregate_dev = {0};

static dhcp_device_context_t *mgmt_intf = NULL;

/** Monitored DHCPv4 message type */
static dhcpv4_message_type_t v4_monitored_msgs[] = {
DHCPv4_MESSAGE_TYPE_DISCOVER,
Expand Down Expand Up @@ -176,6 +178,11 @@ static void handle_dhcp_option_53(dhcp_device_context_t *context,
if ((context->giaddr_ip == giaddr && context->is_uplink && dir == DHCP_TX) ||
(!context->is_uplink && dir == DHCP_RX && iphdr->ip_dst.s_addr == INADDR_BROADCAST)) {
context->counters.v4counters[DHCP_COUNTERS_CURRENT][dir][dhcp_option[2]]++;
// If the packet recieved on the mgmt interface, we don't want to increment the aggregate device
if (context == mgmt_intf)
{
break;
}
aggregate_dev.counters.v4counters[DHCP_COUNTERS_CURRENT][dir][dhcp_option[2]]++;
}
break;
Expand All @@ -186,6 +193,11 @@ static void handle_dhcp_option_53(dhcp_device_context_t *context,
if ((context->giaddr_ip == iphdr->ip_dst.s_addr && context->is_uplink && dir == DHCP_RX) ||
(!context->is_uplink && dir == DHCP_TX)) {
context->counters.v4counters[DHCP_COUNTERS_CURRENT][dir][dhcp_option[2]]++;
// If the packet recieved on the mgmt interface, we don't want to increment the aggregate device
if (context == mgmt_intf)
{
break;
}
aggregate_dev.counters.v4counters[DHCP_COUNTERS_CURRENT][dir][dhcp_option[2]]++;
}
break;
Expand Down Expand Up @@ -224,6 +236,11 @@ static void handle_dhcpv6_option(dhcp_device_context_t *context,
case DHCPv6_MESSAGE_TYPE_RECONFIGURE:
case DHCPv6_MESSAGE_TYPE_INFORMATION_REQUEST:
context->counters.v6counters[DHCP_COUNTERS_CURRENT][dir][dhcp_option]++;
// If the packet recieved on the mgmt interface, we don't want to increment the aggregate device
if (context == mgmt_intf)
{
break;
}
aggregate_dev.counters.v6counters[DHCP_COUNTERS_CURRENT][dir][dhcp_option]++;
break;
default:
Expand Down Expand Up @@ -309,7 +326,7 @@ static void read_callback(int fd, short event, void *arg)
}
}
else if (!is_ipv4 && dhcpv6_enabled && (buffer_sz > UDPv6_START_OFFSET + sizeof(struct udphdr) + DHCPv6_TYPE_LENGTH)) {
const u_char* dhcp_option = context->buffer + dhcp_option_offset;
const u_char* dhcp_header = context->buffer + dhcp_option_offset;
dhcp_packet_direction_t dir = (ethhdr->ether_shost[0] == context->mac[0] &&
ethhdr->ether_shost[1] == context->mac[1] &&
ethhdr->ether_shost[2] == context->mac[2] &&
Expand All @@ -319,23 +336,25 @@ static void read_callback(int fd, short event, void *arg)
DHCP_TX : DHCP_RX;
int offset = 0;
uint16_t option = 0;
uint16_t current_option_len = 0;
// Get to inner DHCP header from encapsulated RELAY_FORWARD or RELAY_REPLY header
while (dhcp_option[offset] == DHCPv6_MESSAGE_TYPE_RELAY_FORWARD || dhcp_option[offset] == DHCPv6_MESSAGE_TYPE_RELAY_REPLY)
while (dhcp_header[offset] == DHCPv6_MESSAGE_TYPE_RELAY_FORWARD || dhcp_header[offset] == DHCPv6_MESSAGE_TYPE_RELAY_REPLY)
{
// Get to DHCPv6_OPTION_RELAY_MSG from all options
offset += DHCPv6_RELAY_MSG_OPTIONS_OFFSET;
option = htons(*((uint16_t*)(&(dhcp_option[offset]))));
option = htons(*((uint16_t*)(&(dhcp_header[offset]))));

while (option != DHCPv6_OPTION_RELAY_MSG)
{
offset += DHCPv6_OPTION_LENGTH;
// Add to offset the option length and get the next option ID
offset += htons(*((uint16_t*)(&(dhcp_option[offset]))));
option = htons(*((uint16_t*)(&(dhcp_option[offset]))));
current_option_len = htons(*((uint16_t*)(&(dhcp_header[offset + DHCPv6_OPTION_LENGTH]))));
offset += DHCPv6_OPTION_LENGTH + DHCPv6_OPTION_LEN_LENGTH + current_option_len;
option = htons(*((uint16_t*)(&(dhcp_header[offset]))));
}
// Set the offset to DHCP-relay-message data
offset += DHCPv6_OPTION_LENGTH + DHCPv6_OPTION_LEN_LENGTH;
}
handle_dhcpv6_option(context, dhcp_option[offset], dir);
handle_dhcpv6_option(context, dhcp_header[offset], dir);
} else {
syslog(LOG_WARNING, "read_callback(%s): read length (%ld) is too small to capture DHCP options",
context->intf, buffer_sz);
Expand Down Expand Up @@ -554,7 +573,7 @@ static dhcp_mon_status_t dhcp_device_check_health(dhcp_mon_check_t check_type,
{
dhcp_mon_status_t rv = DHCP_MON_STATUS_HEALTHY;

if (dhcp_device_is_dhcp_inactive(aggregate_dev.counters.v4counters, aggregate_dev.counters.v6counters, type)) {
if (dhcp_device_is_dhcp_inactive(v4counters, v6counters, type)) {
rv = DHCP_MON_STATUS_INDETERMINATE;
} else if (check_type == DHCP_MON_CHECK_POSITIVE) {
rv = dhcp_device_check_positive_health(v4counters, v6counters, type);
Expand Down Expand Up @@ -948,3 +967,13 @@ void dhcp_device_active_types(bool dhcpv4, bool dhcpv6)
dhcpv4_enabled = dhcpv4;
dhcpv6_enabled = dhcpv6;
}

/**
* @code dhcp_device_init_mgmt_intf(mgmt_intf_context);
*
* @brief assign context address of mgmt interface
*/
void dhcp_device_init_mgmt_intf(dhcp_device_context_t *mgmt_intf_context)
{
mgmt_intf = mgmt_intf_context;
}
11 changes: 11 additions & 0 deletions src/dhcpmon/src/dhcp_device.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -255,4 +255,15 @@ void dhcp_device_print_status(dhcp_device_context_t *context, dhcp_counters_type
* @return none
*/
void dhcp_device_active_types(bool dhcpv4, bool dhcpv6);

/**
* @code dhcp_device_init_mgmt_intf(mgmt_intf_context);
*
* @brief assign context address of mgmt interface
*
* @param mgmt_intf_context MGMT interface context struct address
*
* @return none
*/
void dhcp_device_init_mgmt_intf(dhcp_device_context_t *mgmt_intf_context);
#endif /* DHCP_DEVICE_H_ */
3 changes: 3 additions & 0 deletions src/dhcpmon/src/dhcp_devman.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -148,6 +148,9 @@ int dhcp_devman_add_intf(const char *name, char intf_type)
strncpy(agg_dev->intf + sizeof(AGG_DEV_PREFIX) - 1, name, sizeof(agg_dev->intf) - sizeof(AGG_DEV_PREFIX));
agg_dev->intf[sizeof(agg_dev->intf) - 1] = '\0';
}
else if (rv == 0 && intf_type == 'm') {
dhcp_device_init_mgmt_intf(dev->dev_context);
}

LIST_INSERT_HEAD(&intfs, dev, entry);
}
Expand Down

0 comments on commit 14aca81

Please sign in to comment.