/*
  Copyright (c) 2012, Matthias Schiffer <mschiffer@universe-factory.net>
  All rights reserved.

  Redistribution and use in source and binary forms, with or without
  modification, are permitted provided that the following conditions are met:

    1. Redistributions of source code must retain the above copyright notice,
       this list of conditions and the following disclaimer.
    2. Redistributions in binary form must reproduce the above copyright notice,
       this list of conditions and the following disclaimer in the documentation
       and/or other materials provided with the distribution.

  THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
  AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
  DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
  FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
  SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
  CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
  OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
  OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/


#ifndef _FASTD_FASTD_H_
#define _FASTD_FASTD_H_

#include "types.h"
#include "queue.h"

#include <errno.h>
#include <linux/if_ether.h>
#include <netinet/in.h>
#include <stdarg.h>
#include <stdbool.h>
#include <stddef.h>
#include <stdio.h>
#include <stdint.h>
#include <stdlib.h>
#include <string.h>
#include <syslog.h>
#include <sys/uio.h>
#include <sys/socket.h>
#include <time.h>
#include <unistd.h>


#define FASTD_VERSION "6+"


/* This must be adjusted when new methods are added */
#define MAX_METHODS 3


struct fastd_buffer {
	void *base;
	size_t base_len;

	void *data;
	size_t len;
};

struct fastd_eth_addr {
	uint8_t data[ETH_ALEN];
};

struct fastd_protocol {
	const char *name;

	fastd_protocol_config_t* (*init)(fastd_context_t *ctx);
	void (*peer_configure)(fastd_context_t *ctx, fastd_peer_config_t *peer_conf);

	void (*handshake_init)(fastd_context_t *ctx, const fastd_socket_t *sock, const fastd_peer_address_t *address, const fastd_peer_config_t *peer_conf);
	void (*handshake_handle)(fastd_context_t *ctx, fastd_socket_t *sock, const fastd_peer_address_t *address, const fastd_peer_config_t *peer_conf, const fastd_handshake_t *handshake, const fastd_method_t *method);

	void (*handle_recv)(fastd_context_t *ctx, fastd_peer_t *peer, fastd_buffer_t buffer);
	void (*send)(fastd_context_t *ctx, fastd_peer_t *peer, fastd_buffer_t buffer);

	void (*init_peer_state)(fastd_context_t *ctx, fastd_peer_t *peer);
	void (*reset_peer_state)(fastd_context_t *ctx, fastd_peer_t *peer);
	void (*free_peer_state)(fastd_context_t *ctx, fastd_peer_t *peer);

	void (*generate_key)(fastd_context_t *ctx);
	void (*show_key)(fastd_context_t *ctx);
};

struct fastd_method {
	const char *name;

	size_t (*max_packet_size)(fastd_context_t *ctx);
	size_t (*min_encrypt_head_space)(fastd_context_t *ctx);
	size_t (*min_decrypt_head_space)(fastd_context_t *ctx);
	size_t (*min_encrypt_tail_space)(fastd_context_t *ctx);
	size_t (*min_decrypt_tail_space)(fastd_context_t *ctx);

	fastd_method_session_state_t* (*session_init)(fastd_context_t *ctx, uint8_t *secret, size_t length, bool initiator);
	bool (*session_is_valid)(fastd_context_t *ctx, fastd_method_session_state_t *session);
	bool (*session_is_initiator)(fastd_context_t *ctx, fastd_method_session_state_t *session);
	bool (*session_want_refresh)(fastd_context_t *ctx, fastd_method_session_state_t *session);
	void (*session_free)(fastd_context_t *ctx, fastd_method_session_state_t *session);

	bool (*encrypt)(fastd_context_t *ctx, fastd_peer_t *peer, fastd_method_session_state_t *session, fastd_buffer_t *out, fastd_buffer_t in);
	bool (*decrypt)(fastd_context_t *ctx, fastd_peer_t *peer, fastd_method_session_state_t *session, fastd_buffer_t *out, fastd_buffer_t in);
};

union fastd_peer_address {
	struct sockaddr sa;
	struct sockaddr_in in;
	struct sockaddr_in6 in6;
};

struct fastd_resolve_return {
	char *hostname;
	fastd_peer_address_t constraints;

	fastd_peer_address_t addr;
};

struct fastd_log_file {
	fastd_log_file_t *next;

	int level;
	char *filename;
};

struct fastd_log_fd {
	fastd_log_fd_t *next;

	fastd_log_file_t *config;
	int fd;
};

struct fastd_bind_address {
	fastd_bind_address_t *next;
	fastd_peer_address_t addr;
	char *bindtodev;
};

struct fastd_socket {
	int fd;
	const fastd_bind_address_t *addr;
	fastd_peer_t *peer;
};

struct fastd_peer_group_config {
	fastd_peer_group_config_t *next;
	fastd_peer_group_config_t *parent;
	fastd_peer_group_config_t *children;

	char *name;
	fastd_string_stack_t *peer_dirs;

	/* contraints */
	unsigned max_connections;
};

struct fastd_peer_group {
	fastd_peer_group_t *next;
	fastd_peer_group_t *parent;
	fastd_peer_group_t *children;

	const fastd_peer_group_config_t *conf;

	unsigned n_connections;
};

struct fastd_config {
	int log_stderr_level;
	int log_syslog_level;
	char *log_syslog_ident;
	fastd_log_file_t *log_files;

	unsigned keepalive_interval;
	unsigned peer_stale_time;
	unsigned eth_addr_stale_time;

	unsigned reorder_count;
	unsigned reorder_time;

	unsigned min_handshake_interval;
	unsigned min_resolve_interval;

	char *ifname;

	unsigned n_bind_addrs;
	fastd_bind_address_t *bind_addrs;

	fastd_bind_address_t *bind_addr_default_v4;
	fastd_bind_address_t *bind_addr_default_v6;

	uint16_t mtu;
	fastd_mode_t mode;

	bool forward;

	fastd_drop_caps_t drop_caps;

	char *user;
	char *group;

	uid_t uid;
	gid_t gid;
	size_t n_groups;
	gid_t *groups;

	const fastd_protocol_t *protocol;
	const fastd_method_t *methods[MAX_METHODS];
	const fastd_method_t *method_default;
	char *secret;
	unsigned key_valid;
	unsigned key_refresh;

#ifdef USE_CRYPTO_AES128CTR
	const fastd_crypto_aes128ctr_t *crypto_aes128ctr;
#endif
#ifdef USE_CRYPTO_GHASH
	const fastd_crypto_ghash_t *crypto_ghash;
#endif

	fastd_peer_group_config_t *peer_group;
	fastd_peer_config_t *peers;

	unsigned n_floating;
	unsigned n_v4;
	unsigned n_v6;
	unsigned n_dynamic;
	unsigned n_dynamic_v4;
	unsigned n_dynamic_v6;

	fastd_protocol_config_t *protocol_config;

	char *on_up;
	char *on_up_dir;

	char *on_down;
	char *on_down_dir;

	char *on_establish;
	char *on_establish_dir;

	char *on_disestablish;
	char *on_disestablish_dir;

	bool daemon;
	char *pid_file;

	bool machine_readable;
	bool generate_key;
	bool show_key;
};

struct fastd_context {
	const fastd_config_t *conf;

	fastd_log_fd_t *log_files;

	char *ifname;

	struct timespec now;

	unsigned n_peers;
	fastd_peer_group_t *peer_group;
	fastd_peer_t *peers;
	fastd_queue_t task_queue;

	int resolverfd;
	int resolvewfd;

	int tunfd;

	unsigned n_socks;
	fastd_socket_t *socks;

	fastd_socket_t *sock_default_v4;
	fastd_socket_t *sock_default_v6;

#ifdef USE_CRYPTO_AES128CTR
	fastd_crypto_aes128ctr_context_t *crypto_aes128ctr;
#endif
#ifdef USE_CRYPTO_GHASH
	fastd_crypto_ghash_context_t *crypto_ghash;
#endif

	size_t eth_addr_size;
	size_t n_eth_addr;
	fastd_peer_eth_addr_t *eth_addr;

	unsigned int randseed;

	fastd_protocol_state_t *protocol_state;
};

struct fastd_string_stack {
	fastd_string_stack_t *next;
	char str[];
};


void fastd_send(fastd_context_t *ctx, const fastd_socket_t *sock, const fastd_peer_address_t *address, fastd_buffer_t buffer);
void fastd_send_handshake(fastd_context_t *ctx, const fastd_socket_t *sock, const fastd_peer_address_t *address, fastd_buffer_t buffer);
void fastd_handle_receive(fastd_context_t *ctx, fastd_peer_t *peer, fastd_buffer_t buffer);

fastd_socket_t* fastd_socket_open(fastd_context_t *ctx, fastd_peer_t *peer, int af);

void fastd_setfd(const fastd_context_t *ctx, int fd, int set, int unset);
void fastd_setfl(const fastd_context_t *ctx, int fd, int set, int unset);

void fastd_resolve_peer(fastd_context_t *ctx, fastd_peer_t *peer);

int fastd_vsnprintf(const fastd_context_t *ctx, char *buffer, size_t size, const char *format, va_list ap);
void fastd_logf(const fastd_context_t *ctx, int level, const char *format, ...);

void fastd_read_peer_dir(fastd_context_t *ctx, fastd_config_t *conf, const char *dir);
bool fastd_read_config(fastd_context_t *ctx, fastd_config_t *conf, const char *filename, bool peer_config, int depth);

bool fastd_config_protocol(fastd_context_t *ctx, fastd_config_t *conf, const char *name);
bool fastd_config_method(fastd_context_t *ctx, fastd_config_t *conf, const char *name);
bool fastd_config_crypto(fastd_context_t *ctx, fastd_config_t *conf, const char *alg, const char *impl);
bool fastd_config_add_log_file(fastd_context_t *ctx, fastd_config_t *conf, const char *name, int level);
void fastd_config_bind_address(fastd_context_t *ctx, fastd_config_t *conf, const fastd_peer_address_t *address, const char *bindtodev, bool default_v4, bool default_v6);
void fastd_config_peer_group_push(fastd_context_t *ctx, fastd_config_t *conf, const char *name);
void fastd_config_peer_group_pop(fastd_context_t *ctx, fastd_config_t *conf);
void fastd_config_release(fastd_context_t *ctx, fastd_config_t *conf);
void fastd_configure(fastd_context_t *ctx, fastd_config_t *conf, int argc, char *const argv[]);
void fastd_reconfigure(fastd_context_t *ctx, fastd_config_t *conf);

void fastd_cap_init(fastd_context_t *ctx);
void fastd_cap_drop(fastd_context_t *ctx);

void fastd_random_bytes(fastd_context_t *ctx, void *buffer, size_t len, bool secure);

static inline int fastd_rand(fastd_context_t *ctx, int min, int max) {
	unsigned int r = (unsigned int)rand_r(&ctx->randseed);
	return (r%(max-min) + min);
}


#define FASTD_DEFAULT_LOG_LEVEL	LOG_INFO


#define pr_fatal(ctx, args...) fastd_logf(ctx, LOG_CRIT, args)
#define pr_error(ctx, args...) fastd_logf(ctx, LOG_ERR, args)
#define pr_warn(ctx, args...) fastd_logf(ctx, LOG_WARNING, args)
#define pr_info(ctx, args...) fastd_logf(ctx, LOG_NOTICE, args)
#define pr_verbose(ctx, args...) fastd_logf(ctx, LOG_INFO, args)
#define pr_debug(ctx, args...) fastd_logf(ctx, LOG_DEBUG, args)

#define pr_error_errno(ctx, message) pr_error(ctx, "%s: %s", message, strerror(errno))
#define pr_warn_errno(ctx, message) pr_warn(ctx, "%s: %s", message, strerror(errno))
#define pr_debug_errno(ctx, message) pr_debug(ctx, "%s: %s", message, strerror(errno))

#define exit_fatal(ctx, args...) do { pr_fatal(ctx, args); abort(); } while(0)
#define exit_bug(ctx, message) exit_fatal(ctx, "BUG: %s", message)
#define exit_error(ctx, args...) do { pr_error(ctx, args); exit(1); } while(0)
#define exit_errno(ctx, message) exit_error(ctx, "%s: %s", message, strerror(errno))


#define container_of(ptr, type, member) ({                      \
        const typeof( ((type *)0)->member ) *__mptr = (ptr);    \
        (type *)( (char *)__mptr - offsetof(type,member) );})


static inline size_t alignto(size_t l, size_t a) {
	return ((l+a-1)/a)*a;
}

static inline fastd_buffer_t fastd_buffer_alloc(size_t len, size_t head_space, size_t tail_space) {
	size_t base_len = head_space+len+tail_space;
	void *ptr;
	if (posix_memalign(&ptr, 16, base_len))
		return (fastd_buffer_t){ .base = NULL, .base_len = 0, .data = NULL, .len = 0 };

	return (fastd_buffer_t){ .base = ptr, .base_len = base_len, .data = ptr+head_space, .len = len };
}

static inline void fastd_buffer_free(fastd_buffer_t buffer) {
	free(buffer.base);
}

static inline void fastd_buffer_pull_head(fastd_buffer_t *buffer, size_t len) {
	buffer->data -= len;
	buffer->len += len;

	if (buffer->data < buffer->base)
		abort();
}

static inline void fastd_buffer_push_head(fastd_buffer_t *buffer, size_t len) {
	if (buffer->len < len)
		abort();

	buffer->data += len;
	buffer->len -= len;
}

static inline size_t fastd_max_packet_size(const fastd_context_t *ctx) {
	switch (ctx->conf->mode) {
	case MODE_TAP:
		return ctx->conf->mtu+ETH_HLEN;
	case MODE_TUN:
		return ctx->conf->mtu;
	default:
		exit_bug(ctx, "invalid mode");
	}
}

static inline fastd_string_stack_t* fastd_string_stack_dup(const char *str) {
	fastd_string_stack_t *ret = malloc(sizeof(fastd_string_stack_t) + strlen(str) + 1);
	ret->next = NULL;
	strcpy(ret->str, str);

	return ret;
}

static inline fastd_string_stack_t* fastd_string_stack_dupn(const char *str, size_t len) {
	size_t str_len = strnlen(str, len);
	fastd_string_stack_t *ret = malloc(sizeof(fastd_string_stack_t) + str_len + 1);
	ret->next = NULL;
	strncpy(ret->str, str, str_len);
	ret->str[str_len] = 0;

	return ret;
}

static inline fastd_string_stack_t* fastd_string_stack_push(fastd_string_stack_t *stack, const char *str) {
	fastd_string_stack_t *ret = malloc(sizeof(fastd_string_stack_t) + strlen(str) + 1);
	ret->next = stack;
	strcpy(ret->str, str);

	return ret;
}

static inline void fastd_string_stack_free(fastd_string_stack_t *str) {
	while(str) {
		fastd_string_stack_t *next = str->next;
		free(str);
		str = next;
	}
}

static inline void fastd_socket_close(fastd_context_t *ctx, fastd_socket_t *sock) {
	if (sock->fd >= 0) {
		if(close(sock->fd))
			pr_error_errno(ctx, "closing socket: close");

		sock->fd = -2;
	}
}

static inline bool timespec_after(const struct timespec *tp1, const struct timespec *tp2) {
	return (tp1->tv_sec > tp2->tv_sec ||
		(tp1->tv_sec == tp2->tv_sec && tp1->tv_nsec > tp2->tv_nsec));
}

/* returns (tp1 - tp2) in milliseconds  */
static inline int timespec_diff(const struct timespec *tp1, const struct timespec *tp2) {
	return ((tp1->tv_sec - tp2->tv_sec))*1000 + (tp1->tv_nsec - tp2->tv_nsec)/1e6;
}

static inline bool strequal(const char *str1, const char *str2) {
	if (str1 && str2)
		return (!strcmp(str1, str2));
	else
		return (str1 == str2);
}

#endif /* _FASTD_FASTD_H_ */