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dhtest
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better handling and checking of received packets

Browse Source
changes/54/3254/1
Richard Fuchs 13 years ago
parent 8be8b11c79
commit bd8ffe3f03
3 changed files with 109 additions and 64 deletions
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1
dhtest.c
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@ -55,7 +55,6 @@ char *server_addr = "255.255.255.255";
struct dhcpv4_hdr *dhcph_g = { 0 };
u_int8_t *dhopt_pointer_g = { 0 };
u_int8_t verbose = 0;
u_int8_t dhcp_release_flag = 0;
u_int8_t padding_flag = 0;

169
functions.c
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@ -23,6 +23,7 @@ struct iphdr *iph_g = { 0 };
struct udphdr *uh_g = { 0 };
static struct arp_hdr *arp_hg;
static struct icmp_hdr *icmp_hg;
static unsigned char *dhopt_pointer_g;
/* DHCP packet, option buffer and size of option buffer */
static unsigned char dhcp_packet_send[1518];
@ -35,6 +36,15 @@ static u_char arp_icmp_packet[1514] = { 0 };
static u_char arp_icmp_reply[1514] = { 0 };
static u_int16_t icmp_len = 0;
static int have_set_promisc;
static unsigned int lease_time;
static void read_options(int len);
static int check_packet(int pkt_type, int len);
static int map_all_layer_ptr(int pkt_type);
/*
@ -264,7 +274,7 @@ int recv_packet(int pkt_type)
if (ret < 0)
return timeout_rv;
chk_pkt_state = check_packet(pkt_type);
chk_pkt_state = check_packet(pkt_type, ret);
switch (chk_pkt_state) {
case DHCP_OFFR_RCVD:
@ -627,8 +637,6 @@ int build_packet(int pkt_type)
{
bzero(arp_icmp_reply, sizeof(arp_icmp_reply));
if(pkt_type == ARP_SEND) {
map_all_layer_ptr(ARP_MAP);
struct vlan_eth_hdr *vhdr = (struct vlan_eth_hdr *)arp_icmp_reply;
memcpy(vhdr->vlan_dhost, vlan_hg->vlan_shost, ETHER_ADDR_LEN);
memcpy(vhdr->vlan_shost, dhmac, ETHER_ADDR_LEN);
@ -648,8 +656,6 @@ int build_packet(int pkt_type)
memcpy(arph->target_mac, arp_hg->sender_mac, ETHER_ADDR_LEN);
memcpy(arph->target_ip, arp_hg->sender_ip, IP_ADDR_LEN);
} else if(ICMP_SEND) {
map_all_layer_ptr(ICMP_MAP);
struct vlan_eth_hdr *vhdr = (struct vlan_eth_hdr *)arp_icmp_reply;
memcpy(vhdr->vlan_dhost, vlan_hg->vlan_shost, ETHER_ADDR_LEN);
memcpy(vhdr->vlan_shost, dhmac, ETHER_ADDR_LEN);
@ -691,54 +697,84 @@ int build_packet(int pkt_type)
* Checks whether received packet is DHCP offer/ACK/NACK/ARP/ICMP
* and retunrs the received packet type
*/
int check_packet(int pkt_type)
static int check_packet(int pkt_type, int len)
{
int ret;
if (len < 40)
return UNKNOWN_PACKET;
if(pkt_type == DHCP_MSGOFFER || pkt_type == DHCP_MSGACK) {
map_all_layer_ptr(pkt_type);
if (map_all_layer_ptr(pkt_type))
return UNKNOWN_PACKET;
if (vlan) {
if (ntohs(vlan_hg->vlan_priority_c_vid) != vlan || ntohs(vlan_hg->vlan_tpi) != ETHERTYPE_VLAN)
return UNKNOWN_PACKET;
}
if (dhopt_pointer_g > dhcp_packet_recv + len)
return UNKNOWN_PACKET;
if (iph_g->protocol != 17 || uh_g->source != htons(port) || uh_g->dest != htons(port + 1))
return UNKNOWN_PACKET;
if (htonl(dhcph_g->dhcp_xid) != dhcp_xid)
return UNKNOWN_PACKET;
if(*(dhopt_pointer_g + 2) == DHCP_MSGOFFER)
return DHCP_OFFR_RCVD;
if(*(dhopt_pointer_g + 2) == DHCP_MSGACK)
return DHCP_ACK_RCVD;
if(*(dhopt_pointer_g + 2) == DHCP_MSGNACK)
return DHCP_NAK_RCVD;
ret = DHCP_OFFR_RCVD;
else if(*(dhopt_pointer_g + 2) == DHCP_MSGACK)
ret = DHCP_ACK_RCVD;
else if(*(dhopt_pointer_g + 2) == DHCP_MSGNACK)
ret = DHCP_NAK_RCVD;
else
return UNKNOWN_PACKET;
return UNKNOWN_PACKET;
read_options(len);
return ret;
} else if(pkt_type == ARP_ICMP_RCV) {
map_all_layer_ptr(ARP_MAP);
if(!vlan) {
if (map_all_layer_ptr(ARP_MAP))
return UNKNOWN_PACKET;
if((ntohs(arp_hg->ar_op)) == ARPOP_REQUEST && htonl(ip_address) == arp_hg->target_ip32) {
return ARP_RCVD;
}
} else if(vlan && ntohs(vlan) == vlan_hg->vlan_priority_c_vid) {
if((ntohs(arp_hg->ar_op)) == ARPOP_REQUEST && htonl(ip_address) == arp_hg->target_ip32) {
if (!quiet)
printf("Arp request received\n");
return ARP_RCVD;
}
}
map_all_layer_ptr(ICMP_MAP);
if(!vlan) {
if((ntohs(vlan_hg->vlan_tpi)) == ETHERTYPE_IP && iph_g->protocol == 1 && ip_address == ntohl(iph_g->daddr) && icmp_hg->icmp_type == ICMP_ECHO) {
return ICMP_RCVD;
}
} else if(vlan && ntohs(vlan) == vlan_hg->vlan_priority_c_vid) {
if((ntohs(vlan_hg->vlan_len)) == ETHERTYPE_IP && iph_g->protocol == 1 && ip_address == ntohl(iph_g->daddr) && icmp_hg->icmp_type == ICMP_ECHO) {
return ICMP_RCVD;
}
if(!vlan && vlan_hg->vlan_tpi != htons(ETHERTYPE_ARP))
goto not_arp;
if (vlan && (ntohs(vlan_hg->vlan_priority_c_vid) != vlan
|| vlan_hg->vlan_len != htons(ETHERTYPE_ARP)))
goto not_arp;
if ((unsigned char *) arp_hg + sizeof(*arp_hg) > arp_icmp_packet + len)
return UNKNOWN_PACKET;
if((ntohs(arp_hg->ar_op)) == ARPOP_REQUEST && htonl(ip_address) == arp_hg->target_ip32) {
if (!quiet)
printf("Arp request received\n");
return ARP_RCVD;
}
return UNKNOWN_PACKET;
not_arp:
if (map_all_layer_ptr(ICMP_MAP))
return UNKNOWN_PACKET;
if(!vlan && vlan_hg->vlan_tpi != htons(ETHERTYPE_IP))
goto not_icmp;
if (vlan && (ntohs(vlan_hg->vlan_priority_c_vid) != vlan
|| vlan_hg->vlan_len != htons(ETHERTYPE_IP)))
goto not_icmp;
if ((unsigned char *) icmp_hg + sizeof(*icmp_hg) > arp_icmp_packet + len)
return -1;
if (iph_g->protocol != 1)
goto not_icmp;
if(ip_address == ntohl(iph_g->daddr) && icmp_hg->icmp_type == ICMP_ECHO)
return ICMP_RCVD;
not_icmp:
return UNKNOWN_PACKET;
}
return 0;
}
@ -749,17 +785,31 @@ int check_packet(int pkt_type)
*/
int set_serv_id_opt50()
{
map_all_layer_ptr(DHCP_MSGOFFER);
option50_ip = dhcph_g->dhcp_yip;
while(*(dhopt_pointer_g) != DHCP_END) {
if(*(dhopt_pointer_g) == DHCP_SERVIDENT) {
memcpy(&server_id, (u_int32_t *)(dhopt_pointer_g + 2), 4);
return 0;
}
static void read_options(int len) {
unsigned char *p = dhopt_pointer_g,
*end = dhcp_packet_recv + len;
while(*(p) != DHCP_END && p < end) {
if ((p + *(p + 1) + 2) > end)
break;
switch(*(p)) {
case DHCP_SERVIDENT:
server_id = *(u_int32_t *)(p + 2);
break;
case DHCP_LEASETIME:
lease_time = ntohl(*(u_int32_t *)(p + 2));
break;
}
dhopt_pointer_g = dhopt_pointer_g + *(dhopt_pointer_g + 1) + 2;
p = p + *(p + 1) + 2;
}
return 0;
}
/*
@ -768,9 +818,9 @@ int set_serv_id_opt50()
int print_dhinfo(int pkt_type)
{
u_int16_t tmp;
if(pkt_type == DHCP_MSGOFFER) {
map_all_layer_ptr(DHCP_MSGOFFER);
unsigned char *p;
if(pkt_type == DHCP_MSGOFFER) {
printf("\nDHCP offer details\n");
printf("----------------------------------------------------------\n");
printf("DHCP offered IP from server - %s\n", get_ip_str(dhcph_g->dhcp_yip));
@ -780,8 +830,6 @@ int print_dhinfo(int pkt_type)
printf("DHCP Relay agent IP - %s\n", get_ip_str(dhcph_g->dhcp_gip));
}
} else if( pkt_type == DHCP_MSGACK) {
map_all_layer_ptr(DHCP_MSGACK);
printf("\nDHCP ack details\n");
printf("----------------------------------------------------------\n");
printf("DHCP offered IP from server - %s\n", get_ip_str(dhcph_g->dhcp_yip));
@ -792,52 +840,53 @@ int print_dhinfo(int pkt_type)
}
}
while(*(dhopt_pointer_g) != DHCP_END) {
p = dhopt_pointer_g;
while(*(p) != DHCP_END) {
switch(*(dhopt_pointer_g)) {
switch(*(p)) {
case DHCP_SERVIDENT:
printf("DHCP server - %s\n", get_ip_str(*(u_int32_t *)(dhopt_pointer_g + 2)));
printf("DHCP server - %s\n", get_ip_str(*(u_int32_t *)(p + 2)));
break;
case DHCP_LEASETIME:
printf("Lease time - %d Days %d Hours %d Minutes\n", \
(ntohl(*(u_int32_t *)(dhopt_pointer_g + 2))) / (3600 * 24), \
((ntohl(*(u_int32_t *)(dhopt_pointer_g + 2))) % (3600 * 24)) / 3600, \
(((ntohl(*(u_int32_t *)(dhopt_pointer_g + 2))) % (3600 * 24)) % 3600) / 60);
(ntohl(*(u_int32_t *)(p + 2))) / (3600 * 24), \
((ntohl(*(u_int32_t *)(p + 2))) % (3600 * 24)) / 3600, \
(((ntohl(*(u_int32_t *)(p + 2))) % (3600 * 24)) % 3600) / 60);
break;
case DHCP_SUBNETMASK:
printf("Subnet mask - %s\n", get_ip_str(*(u_int32_t *)(dhopt_pointer_g + 2)));
printf("Subnet mask - %s\n", get_ip_str(*(u_int32_t *)(p + 2)));
break;
case DHCP_ROUTER:
for(tmp = 0; tmp < (*(dhopt_pointer_g + 1) / 4); tmp++) {
printf("Router/gateway - %s\n", get_ip_str(*(u_int32_t *)(dhopt_pointer_g + 2 + (tmp * 4))));
for(tmp = 0; tmp < (*(p + 1) / 4); tmp++) {
printf("Router/gateway - %s\n", get_ip_str(*(u_int32_t *)(p + 2 + (tmp * 4))));
}
break;
case DHCP_DNS:
for(tmp = 0; tmp < ((*(dhopt_pointer_g + 1)) / 4); tmp++) {
printf("DNS server - %s\n", get_ip_str(*(u_int32_t *)(dhopt_pointer_g + 2 + (tmp * 4))));
for(tmp = 0; tmp < ((*(p + 1)) / 4); tmp++) {
printf("DNS server - %s\n", get_ip_str(*(u_int32_t *)(p + 2 + (tmp * 4))));
}
break;
case DHCP_FQDN:
{
/* Minus 3 beacause 3 bytes are used to flags, rcode1 and rcode2 */
u_int32_t size = (u_int32_t)*(dhopt_pointer_g + 1) - 3;
u_int32_t size = (u_int32_t)*(p + 1) - 3;
/* Plus 2 to add string terminator */
u_char fqdn_client_name[size + 1];
/* Plus 5 to reach the beginning of the string */
memcpy(fqdn_client_name, dhopt_pointer_g + 5, size);
memcpy(fqdn_client_name, p + 5, size);
fqdn_client_name[size] = '\0';
printf("FQDN Client name - %s\n", fqdn_client_name);
}
}
dhopt_pointer_g = dhopt_pointer_g + *(dhopt_pointer_g + 1) + 2;
p = p + *(p + 1) + 2;
}
printf("----------------------------------------------------------\n\n");
@ -847,7 +896,7 @@ int print_dhinfo(int pkt_type)
/*
* Function maps all pointers on OFFER/ACK/ARP/ICMP packet
*/
int map_all_layer_ptr(int pkt_type)
static int map_all_layer_ptr(int pkt_type)
{
switch (pkt_type) {
case DHCP_MSGOFFER:

3
headers.h
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@ -39,8 +39,6 @@ int build_optioneof(void); /* End of option */
int build_dhpacket(int pkt_type); /* Build DHCP disc, req packets */
int build_packet(int pkt_type); /* Builds ARP and ICMP reply packets */
int print_buff(u_int8_t *buff, int size);/* Debug routine */
int map_all_layer_ptr(int pkt_type); /* maps all layer pointer on DHCP packet */
int check_packet(int pkt_type); /* Checks the packet for DHCP offer & ack */
int print_dhinfo(int pkt_type); /* Prints DHCP offer & ack informations */
int log_dhinfo(void); /* Logs DHCP IP info to log file */
int get_dhinfo(void); /* Reads log file for mac, ip, serv_ip info */
@ -331,7 +329,6 @@ extern char *giaddr;
extern char *server_addr;
extern struct dhcpv4_hdr *dhcph_g;
extern u_int8_t *dhopt_pointer_g;
extern u_char dhmac[ETHER_ADDR_LEN];
extern u_char dmac[ETHER_ADDR_LEN];

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