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#ifndef PKT_H
#define PKT_H 1
#include <stdint.h>
#ifdef WIN32
#include <winsock2.h>
typedef int socklen_t;
typedef uint32_t in_addr_t;
#define ETH_ALEN 6 /* Octets in one ethernet addr */
struct ether_header {
u_int8_t ether_dhost[ETH_ALEN]; /* destination eth addr */
u_int8_t ether_shost[ETH_ALEN]; /* source ether addr */
u_int16_t ether_type; /* packet type ID field */
};
#endif /* WIN32 */
/** Resend packets after this interval (in seconds) */
#define kResend_interval 1.5
/** ping_tunnel_pkt_t: This data structure represents the header of a ptunnel
* packet, consisting of a magic number, the tunnel's destination IP and port,
* as well as some other fields. Note that the dest IP and port is only valid
* in packets from the client to the proxy.
*/
typedef struct {
/** magic number, used to identify ptunnel packets. */
uint32_t magic;
/** destination IP and port (used by proxy to figure */
uint32_t dst_ip;
/** out where to tunnel to) */
uint32_t dst_port;
/** current connection state; see constants above. */
uint32_t state;
/** sequence number of last packet received from other end */
uint32_t ack;
/** length of data buffer */
uint32_t data_len;
/** sequence number of this packet */
uint16_t seq_no;
/** id number, used to separate different tunnels from each other */
uint16_t id_no;
/** optional data buffer */
char data[0];
} __attribute__ ((packed)) ping_tunnel_pkt_t;
/** ip_packet_t: This is basically my own definition of the IP packet, which
* of course complies with the official definition ;) See any good book on IP
* (or even the RFC) for info on the contents of this packet.
*/
typedef struct {
uint8_t vers_ihl;
uint8_t tos;
uint16_t pkt_len;
uint16_t id;
uint16_t flags_frag_offset;
uint8_t ttl;
uint8_t proto; // 1 for ICMP
uint16_t checksum;
uint32_t src_ip;
uint32_t dst_ip;
char data[0];
} __attribute__ ((packed)) ip_packet_t;
/** icmp_echo_packet_t: This is the definition of a standard ICMP header. The
* ptunnel packets are constructed as follows:
* [ ip header (20 bytes) ]
* [ icmp header (8 bytes) ]
* [ ptunnel header (28 bytes) ]
*
* We actually only create the ICMP and ptunnel headers, the IP header is
* taken care of by the OS.
*/
typedef struct {
uint8_t type;
uint8_t code;
uint16_t checksum;
uint16_t identifier;
uint16_t seq;
char data[0];
} __attribute__ ((packed)) icmp_echo_packet_t;
typedef struct forward_desc_t forward_desc_t;
typedef struct icmp_desc_t icmp_desc_t;
void handle_packet(char *buf, unsigned bytes, int is_pcap, struct sockaddr_in *addr, int icmp_sock);
void handle_data(icmp_echo_packet_t *pkt, int total_len, forward_desc_t **ring,
int *await_send, int *insert_idx, uint16_t *next_expected_seq);
void handle_ack(uint16_t seq_no, icmp_desc_t *ring, int *packets_awaiting_ack,
int one_ack_only, int insert_idx, int *first_ack,
uint16_t *remote_ack, int is_pcap);
#endif
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