#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#ifndef USE_NETLIB
#include <net/ethernet.h>
#include <netinet/in.h>
#ifdef __linux__
#include <netinet/ether.h>
#endif
#include <arpa/inet.h>
#else
#include <netlib.h>
#endif
#include "pktlib.h"
#include "pktbuf.h"
struct dhcp {
 unsigned char message_type;
 unsigned char hardware_type;
 unsigned char hardware_addrlen;
 unsigned char hops;
 unsigned int transaction_id;
 unsigned short seconds_elapsed;
 unsigned short flags;
 unsigned int client_ip_address;
 unsigned int your_ip_address;
 unsigned int next_server_ip_address;
 unsigned int relay_agent_ip_address;
 char client_mac_address[6];
 unsigned char padding[10];
 unsigned char server_host_name[64];
 unsigned char boot_file_name[128];
 unsigned int magic_cookie;
#define DHCP_MAGIC_COOKIE_DHCP 0x63825363
 unsigned char option[0];
};
struct dhcp_option {
 unsigned char type;
#define DHCP_OPTION_TYPE_SUBNET_MASK 0x01
#define DHCP_OPTION_TYPE_HOST_NAME 0x0c
#define DHCP_OPTION_TYPE_DOMAIN_NAME 0x0f
#define DHCP_OPTION_TYPE_REQ_IP_ADDR 0x32
#define DHCP_OPTION_TYPE_IP_LEASE_TIME 0x33
#define DHCP_OPTION_TYPE_MESSAGE_TYPE 0x35
#define DHCP_OPTION_TYPE_SERVER_ID 0x36
#define DHCP_OPTION_TYPE_PARAM_REQLIST 0x37
#define DHCP_OPTION_TYPE_CLIENT_ID 0x3d
#define DHCP_OPTION_TYPE_END 0xff
 unsigned char length;
 unsigned char data[0];
};
struct dhcp_params {
 struct ether_addr src_macaddr;
 struct ether_addr client_macaddr;
 unsigned int server_ipaddr;
 unsigned int transaction_id;
 unsigned int your_ip_address;
 unsigned int subnet_mask;
};
#define DHCP_TRANSACTION_ID 0x12345678
static char *macaddr_s(char macaddr[])
{
 return ether_ntoa((struct ether_addr *)macaddr);
}
static char *ipaddr_s(unsigned int ipaddr)
{
 struct in_addr in;
 in.s_addr = htonl(ipaddr);
 return inet_ntoa(in);
}
static int send_dhcp_offer(pktif_t pktif, struct header_param *paramp,
			 struct dhcp_params *dhcpparams)
{
 pktbuf_t pktbuf;
 struct header_param param;
 struct dhcp *dhcphdr;
 struct dhcp_option *dhcpopt;
 unsigned int val4;
 memcpy(param.ethernet.src_macaddr, &dhcpparams->src_macaddr, ETHER_ADDR_LEN);
 memcpy(param.ethernet.dst_macaddr, &paramp->ethernet.src_macaddr, ETHER_ADDR_LEN);
 param.ethernet.type = ETHERTYPE_IP;
 param.ip.id = 0x1234;
 param.ip.ttl = 64;
 param.ip.protocol = IPPROTO_UDP;
 param.ip.src_ipaddr = dhcpparams->server_ipaddr;
 param.ip.dst_ipaddr = dhcpparams->your_ip_address;
 param.udp.src_port = 67;
 param.udp.dst_port = 68;
 pktbuf = pktbuf_create(-1);
 dhcphdr = (struct dhcp *)pktbuf_add_header(pktbuf, sizeof(*dhcphdr) + 64);
 memset(dhcphdr, 0, sizeof(*dhcphdr));
 dhcphdr->message_type = 2; /* Boot Reply */
 dhcphdr->hardware_type = 1; /* Ethernet */
 dhcphdr->hardware_addrlen = ETHER_ADDR_LEN;
 dhcphdr->transaction_id = htonl(dhcpparams->transaction_id);
 dhcphdr->your_ip_address = htonl(dhcpparams->your_ip_address);
 memcpy(dhcphdr->client_mac_address, &dhcpparams->client_macaddr, ETHER_ADDR_LEN);
 dhcphdr->magic_cookie = htonl(DHCP_MAGIC_COOKIE_DHCP);
 dhcpopt = (struct dhcp_option *)dhcphdr->option;
 dhcpopt->type = DHCP_OPTION_TYPE_MESSAGE_TYPE;
 dhcpopt->length = 1;
 dhcpopt->data[0] = 2; /* Offer */
 dhcpopt = (struct dhcp_option *)((char *)dhcpopt + 2 + dhcpopt->length);
 dhcpopt->type = DHCP_OPTION_TYPE_SERVER_ID;
 dhcpopt->length = 4;
 val4 = htonl(dhcpparams->server_ipaddr);
 memcpy(dhcpopt->data, &val4, sizeof(val4));
 dhcpopt = (struct dhcp_option *)((char *)dhcpopt + 2 + dhcpopt->length);
 dhcpopt->type = DHCP_OPTION_TYPE_IP_LEASE_TIME;
 dhcpopt->length = 4;
 val4 = htonl(600);
 memcpy(dhcpopt->data, &val4, sizeof(val4));
 dhcpopt = (struct dhcp_option *)((char *)dhcpopt + 2 + dhcpopt->length);
 dhcpopt->type = DHCP_OPTION_TYPE_SUBNET_MASK;
 dhcpopt->length = 4;
 val4 = htonl(dhcpparams->subnet_mask);
 memcpy(dhcpopt->data, &val4, sizeof(val4));
 dhcpopt = (struct dhcp_option *)((char *)dhcpopt + 2 + dhcpopt->length);
 dhcpopt->type = DHCP_OPTION_TYPE_DOMAIN_NAME;
 dhcpopt->length = 11;
 memcpy(dhcpopt->data, "example.org", 11);
 dhcpopt = (struct dhcp_option *)((char *)dhcpopt + 2 + dhcpopt->length);
 dhcpopt->type = DHCP_OPTION_TYPE_END;
 dhcpopt = (struct dhcp_option *)((char *)dhcpopt + 1);
 pktbuf_set_size(pktbuf, (char *)dhcpopt - (char *)dhcphdr);
 pktbuf = pktbuf_make_udp(pktbuf, &param);
 pktbuf = pktbuf_make_ip(pktbuf, &param);
 pktbuf = pktbuf_checksum_correct_ip(pktbuf);
 pktbuf = pktbuf_make_ethernet(pktbuf, &param);
 pktbuf = pktbuf_send(pktif, pktbuf);
 if (pktbuf) {
 pktbuf_destroy(pktbuf);
 return 0;
 }
 return 1;
}
static int send_dhcp_ack(pktif_t pktif, struct header_param *paramp,
			 struct dhcp_params *dhcpparams)
{
 pktbuf_t pktbuf;
 struct header_param param;
 struct dhcp *dhcphdr;
 struct dhcp_option *dhcpopt;
 unsigned int val4;
 memcpy(param.ethernet.src_macaddr, &dhcpparams->src_macaddr, ETHER_ADDR_LEN);
 memcpy(param.ethernet.dst_macaddr, &paramp->ethernet.src_macaddr, ETHER_ADDR_LEN);
 param.ethernet.type = ETHERTYPE_IP;
 param.ip.id = 0x1234;
 param.ip.ttl = 64;
 param.ip.protocol = IPPROTO_UDP;
 param.ip.src_ipaddr = dhcpparams->server_ipaddr;
 param.ip.dst_ipaddr = dhcpparams->your_ip_address;
 param.udp.src_port = 67;
 param.udp.dst_port = 68;
 pktbuf = pktbuf_create(-1);
 dhcphdr = (struct dhcp *)pktbuf_add_header(pktbuf, sizeof(*dhcphdr) + 64);
 memset(dhcphdr, 0, sizeof(*dhcphdr));
 dhcphdr->message_type = 2; /* Boot Reply */
 dhcphdr->hardware_type = 1; /* Ethernet */
 dhcphdr->hardware_addrlen = ETHER_ADDR_LEN;
 dhcphdr->transaction_id = htonl(dhcpparams->transaction_id);
 dhcphdr->your_ip_address = htonl(dhcpparams->your_ip_address);
 memcpy(dhcphdr->client_mac_address, &dhcpparams->client_macaddr, ETHER_ADDR_LEN);
 dhcphdr->magic_cookie = htonl(DHCP_MAGIC_COOKIE_DHCP);
 dhcpopt = (struct dhcp_option *)dhcphdr->option;
 dhcpopt->type = DHCP_OPTION_TYPE_MESSAGE_TYPE;
 dhcpopt->length = 1;
 dhcpopt->data[0] = 5; /* ACK */
 dhcpopt = (struct dhcp_option *)((char *)dhcpopt + 2 + dhcpopt->length);
 dhcpopt->type = DHCP_OPTION_TYPE_SERVER_ID;
 dhcpopt->length = 4;
 val4 = htonl(dhcpparams->server_ipaddr);
 memcpy(dhcpopt->data, &val4, sizeof(val4));
 dhcpopt = (struct dhcp_option *)((char *)dhcpopt + 2 + dhcpopt->length);
 dhcpopt->type = DHCP_OPTION_TYPE_IP_LEASE_TIME;
 dhcpopt->length = 4;
 val4 = htonl(600);
 memcpy(dhcpopt->data, &val4, sizeof(val4));
 dhcpopt = (struct dhcp_option *)((char *)dhcpopt + 2 + dhcpopt->length);
 dhcpopt->type = DHCP_OPTION_TYPE_SUBNET_MASK;
 dhcpopt->length = 4;
 val4 = htonl(dhcpparams->subnet_mask);
 memcpy(dhcpopt->data, &val4, sizeof(val4));
 dhcpopt = (struct dhcp_option *)((char *)dhcpopt + 2 + dhcpopt->length);
 dhcpopt->type = DHCP_OPTION_TYPE_DOMAIN_NAME;
 dhcpopt->length = 11;
 memcpy(dhcpopt->data, "example.org", 11);
 dhcpopt = (struct dhcp_option *)((char *)dhcpopt + 2 + dhcpopt->length);
 dhcpopt->type = DHCP_OPTION_TYPE_END;
 dhcpopt = (struct dhcp_option *)((char *)dhcpopt + 1);
 pktbuf_set_size(pktbuf, (char *)dhcpopt - (char *)dhcphdr);
 pktbuf = pktbuf_make_udp(pktbuf, &param);
 pktbuf = pktbuf_make_ip(pktbuf, &param);
 pktbuf = pktbuf_checksum_correct_ip(pktbuf);
 pktbuf = pktbuf_make_ethernet(pktbuf, &param);
 pktbuf = pktbuf_send(pktif, pktbuf);
 if (pktbuf) {
 pktbuf_destroy(pktbuf);
 return 0;
 }
 return 1;
}
static int analyze_dhcp_discover_or_request(struct dhcp *dhcphdr,
					 struct dhcp_params *dhcpparams)
{
 struct dhcp_option *dhcpopt;
 unsigned int ipaddr;
 if (dhcphdr->message_type != 1) /* Boot Request */
 return 0;
 if (dhcphdr->hardware_type != 1) /* Ethernet */
 return 0;
 if (dhcphdr->hardware_addrlen != ETHER_ADDR_LEN)
 return 0;
 if (ntohl(dhcphdr->magic_cookie) != DHCP_MAGIC_COOKIE_DHCP)
 return 0;
 dhcpparams->transaction_id = ntohl(dhcphdr->transaction_id);
 memcpy(&dhcpparams->client_macaddr, dhcphdr->client_mac_address, ETHER_ADDR_LEN);
 printf("Client MAC Address : %s\n", macaddr_s(dhcphdr->client_mac_address));
 dhcpopt = (struct dhcp_option *)dhcphdr->option;
 while (1) {
 if (dhcpopt->type == DHCP_OPTION_TYPE_END)
 break;
 if (dhcpopt->type == DHCP_OPTION_TYPE_SERVER_ID) {
 ipaddr = htonl(dhcpparams->server_ipaddr);
 if (memcmp(&ipaddr, dhcpopt->data, sizeof(ipaddr)))
	return 0;
 memcpy(&ipaddr, dhcpopt->data, sizeof(ipaddr));
 ipaddr = ntohl(ipaddr);
 printf("Server ID : %s\n", ipaddr_s(ipaddr));
 }
 if (dhcpopt->type == DHCP_OPTION_TYPE_REQ_IP_ADDR) {
 ipaddr = htonl(dhcpparams->your_ip_address);
 if (memcmp(&ipaddr, dhcpopt->data, sizeof(ipaddr)))
	return 0;
 memcpy(&ipaddr, dhcpopt->data, sizeof(ipaddr));
 ipaddr = ntohl(ipaddr);
 printf("Requested IP Address: %s\n", ipaddr_s(ipaddr));
 }
 dhcpopt = (struct dhcp_option *)((char *)dhcpopt + 2 + dhcpopt->length);
 }
 return 1;
}
static int analyze_dhcp(struct dhcp *dhcphdr,
			struct dhcp_params *dhcpparams)
{
 struct dhcp_option *dhcpopt;
 int type;
 dhcpopt = (struct dhcp_option *)dhcphdr->option;
 while (1) {
 if (dhcpopt->type == DHCP_OPTION_TYPE_END)
 break;
 if (dhcpopt->type == DHCP_OPTION_TYPE_MESSAGE_TYPE) {
 type = dhcpopt->data[0];
 switch (type) {
 case 1: /* Discover */
 case 3: /* Request */
	switch (type) {
	case 1: printf("DHCP DISCOVER:\n"); break;
	case 3: printf("DHCP REQUEST:\n"); break;
	default: break;
	}
	if (analyze_dhcp_discover_or_request(dhcphdr, dhcpparams)> 0)
	 return type;
	break;
 case 2: /* Offer */
 case 5: /* ACK */
 default: /* Unknown */
	break;
 }
 }
 dhcpopt = (struct dhcp_option *)((char *)dhcpopt + 2 + dhcpopt->length);
 }
 return 0;
}
static int recv_dhcp(pktif_t pktif, struct header_param *paramp,
		 struct dhcp_params *dhcpparams)
{
 pktbuf_t pktbuf;
 int r = 0, next, payload = 0;
 struct header_param param;
 pktbuf = pktbuf_recv(pktif, 0);
 if (pktbuf)
 pktbuf_destroy(pktbuf);
 next = pktif_get_linktype(pktif);
 switch (next) {
 case DLT_EN10MB:
 r = pktbuf_analyze_ethernet(pktbuf, &param);
 break;
 default:
 break;
 }
 if (r> 0) {
 switch (next) {
 case DLT_EN10MB:
 printf("Ethernet:\n");
 printf("\tsrc macaddr: %s\n", macaddr_s(param.ethernet.src_macaddr));
 printf("\tdst macaddr: %s\n", macaddr_s(param.ethernet.dst_macaddr));
 printf("\ttype : %04x\n", param.ethernet.type);
 payload += param.ethernet.header_size;
 next = param.ethernet.type;
 break;
 default:
 next = -1;
 break;
 }
 }
 if (r> 1) {
 switch (next) {
 case ETHERTYPE_IP:
 printf("IP:\n");
 printf("\tid : %04x\n", param.ip.id);
 printf("\tttl : %04x\n", param.ip.ttl);
 printf("\tprotocol : %d\n", param.ip.protocol);
 printf("\tsrc ipaddr: %s\n", ipaddr_s(param.ip.src_ipaddr));
 printf("\tdst ipaddr: %s\n", ipaddr_s(param.ip.dst_ipaddr));
 payload += param.ip.header_size;
 next = param.ip.protocol;
 break;
 default:
 next = -1;
 break;
 }
 }
 if (r> 2) {
 switch (next) {
 case IPPROTO_UDP:
 printf("UDP:\n");
 printf("\tsrc port: %d\n", param.udp.src_port);
 printf("\tdst port: %d\n", param.udp.dst_port);
 payload += param.udp.header_size;
 if ((param.udp.src_port == 68) && (param.udp.dst_port == 67)) {
	if (paramp)
	 memcpy(paramp, &param, sizeof(*paramp));
	return analyze_dhcp((struct dhcp *)(pktbuf_get_header(pktbuf) + payload), dhcpparams);
 }
 break;
 default:
 break;
 }
 }
 return 0;
}
int main(int argc, char *argv[])
{
 pktif_t pktif;
 struct header_param param;
 struct dhcp_params dhcpparams;
 argc--;
 argv++;
 pktif = pktif_open(argv[0], PKTIF_OPEN_FLAG_RECV_NOTSENT, 0);
 memcpy(&dhcpparams.src_macaddr, ether_aton(argv[1]), ETHER_ADDR_LEN);
 dhcpparams.server_ipaddr = (unsigned int)ntohl(inet_addr(argv[2]));
 dhcpparams.your_ip_address = (unsigned int)ntohl(inet_addr(argv[3]));
 dhcpparams.subnet_mask = (unsigned int)ntohl(inet_addr(argv[4]));
 while (recv_dhcp(pktif, &param, &dhcpparams) != 1) /* Discover */
 ;
 send_dhcp_offer(pktif, &param, &dhcpparams);
 while (recv_dhcp(pktif, &param, &dhcpparams) != 3) /* Request */
 ;
 send_dhcp_ack(pktif, &param, &dhcpparams);
 return 0;
}
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