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Diffstat (limited to 'src/pdesc.h')
| -rw-r--r-- | src/pdesc.h | 136 |
1 files changed, 136 insertions, 0 deletions
diff --git a/src/pdesc.h b/src/pdesc.h new file mode 100644 index 0000000..18751b7 --- /dev/null +++ b/src/pdesc.h @@ -0,0 +1,136 @@ +#ifndef PDESC_H +#define PDESC_H 1 + +#include <stdint.h> +#include <sys/socket.h> +#include <netinet/in.h> +#include <arpa/inet.h> + +#include "pkt.h" +#include "challenge.h" +#include "pconfig.h" + +/** forward_desc_t: Describes a piece of that needs to be forwarded. This + * structure is used for receiving data from the network, and for subsequent + * forwarding over TCP: + * + * 1. Client sends data to proxy over ICMP + * 2. Proxy receives the data, and puts it into a forward_desc_t + * 3. The proxy starts send()-ing the data over the TCP socket to the destination, + * decreasing forward_desc_t->remaining with the number of bytes transferred. + * 4. Once remaining reaches 0, the forward_desc_t is removed from the receive + * ring. + * + * The same procedure is followed in proxy-to-client communication. Just replace + * proxy with client and vice versa in the list above. + */ +typedef struct forward_desc_t { + /** ping_tunnel_pkt_t seq_no */ + int seq_no; + /** length of data */ + int length; + /** amount of data not yet transferred */ + int remaining; + char data[0]; +} forward_desc_t; + +/** icmp_desc_t: This structure is used to track the ICMP packets sent by either + * the client or proxy. The last_resend variable is used to prevent resending + * the packet too often. Once the packet is acknowledged by the remote end, + * it will be removed from the send-ring, freeing up space for more outgoing + * ICMP packets. + */ +typedef struct icmp_desc_t { + /** total length of ICMP packet, including ICMP header and ptunnel data. */ + int pkt_len; + double last_resend; + int resend_count; + uint16_t seq_no; + uint16_t icmp_id; + icmp_echo_packet_t *pkt; +} icmp_desc_t; + +/** xfer_stats_t: Various transfer statistics, such as bytes sent and received, + * number of ping packets sent/received, etc. + */ +typedef struct xfer_stats_t { + double bytes_in; + double bytes_out; + uint32_t icmp_in; + uint32_t icmp_out; + uint32_t icmp_resent; + uint32_t icmp_ack_out; +} xfer_stats_t; + +/** proxy_desc_t: This massive structure describes a tunnel instance. + */ +typedef struct proxy_desc_t { + /** ICMP or UDP socket */ + int sock; + /** number of bytes in receive buffer */ + int bytes; + /** set to true once this instance should be removed */ + int should_remove; + /** data buffer, used to receive ping and pong packets */ + char *buf; + uint16_t id_no; + uint16_t my_seq; + uint16_t ping_seq; + uint16_t next_remote_seq; + uint16_t pkt_type; + uint16_t remote_ack_val; + uint16_t icmp_id; + /** first available slot in recv ring */ + int recv_idx; + /** current slot in recv ring being transferred */ + int recv_xfer_idx; + /** first available slot in send ring */ + int send_idx; + /** first packet in send ring not yet acked */ + int send_first_ack; + /** number of items in recv ring awaiting send */ + int recv_wait_send; + /** number of items in send ring awaiting ack */ + int send_wait_ack; + int next_resend_start; + int authenticated; + /** Contains the challenge, if used. */ + challenge_t *challenge; + /** Protocol state */ + uint32_t state; + /** Either kProxy_flag or kUser_flag */ + uint32_t type_flag; + /** IP and port to which data should be forwarded. */ + uint32_t dst_ip; + uint32_t dst_port; + /** Same as above */ + struct sockaddr_in dest_addr; + /** Time when last ack packet was sent. */ + double last_ack; + /** Time when a packet was last received. */ + double last_activity; + icmp_desc_t send_ring[kPing_window_size]; + forward_desc_t *recv_ring[kPing_window_size]; + xfer_stats_t xfer; + struct proxy_desc_t *next; +} proxy_desc_t; + + +proxy_desc_t* create_and_insert_proxy_desc(uint16_t id_no, uint16_t icmp_id, + int sock, struct sockaddr_in *addr, + uint32_t dst_ip, uint32_t dst_port, + uint32_t init_state, uint32_t type); + +void remove_proxy_desc(proxy_desc_t *cur, proxy_desc_t *prev); + +forward_desc_t* create_fwd_desc(uint16_t seq_no, uint32_t data_len, char *data); + +int queue_packet(int icmp_sock, uint8_t type, char *buf, int num_bytes, + uint16_t id_no, uint16_t icmp_id, uint16_t *seq, icmp_desc_t ring[], + int *insert_idx, int *await_send, uint32_t ip, uint32_t port, + uint32_t state, struct sockaddr_in *dest_addr, uint16_t next_expected_seq, + int *first_ack, uint16_t *ping_seq); + +uint32_t send_packets(forward_desc_t *ring[], int *xfer_idx, int *await_send, int *sock); + +#endif |