/**
 * @file BAddr.h
 * @author Ambroz Bizjak <ambrop7@gmail.com>
 * 
 * @section LICENSE
 * 
 * This file is part of BadVPN.
 * 
 * BadVPN is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2
 * as published by the Free Software Foundation.
 * 
 * BadVPN is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 * 
 * You should have received a copy of the GNU General Public License along
 * with this program; if not, write to the Free Software Foundation, Inc.,
 * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
 * 
 * @section DESCRIPTION
 * 
 * Network address abstractions used by {@link BSocket}.
 */

#ifndef BADVPN_SYSTEM_BADDR_H
#define BADVPN_SYSTEM_BADDR_H

#include <stdint.h>
#include <limits.h>
#include <stdlib.h>
#include <string.h>
#include <stdio.h>
#include <inttypes.h>

#ifdef BADVPN_USE_WINAPI
#include <ws2tcpip.h>
#else
#include <sys/types.h>
#include <sys/socket.h>
#include <netdb.h>
#endif

#include <misc/byteorder.h>
#include <misc/debug.h>

#define BADDR_TYPE_NONE 0
#define BADDR_TYPE_IPV4 1
#define BADDR_TYPE_IPV6 2
#ifndef BADVPN_USE_WINAPI
    #define BADDR_TYPE_UNIX 3 // only a domain number for BSocket
#endif

#define BADDR_MAX_ADDR_LEN 128

#define BIPADDR_MAX_PRINT_LEN 40
#define BADDR_MAX_PRINT_LEN 46

typedef struct {
    int type;
    union {
        uint32_t ipv4;
        uint8_t ipv6[16];
    };
} BIPAddr;

static void BIPAddr_InitInvalid (BIPAddr *addr);

static void BIPAddr_InitIPv4 (BIPAddr *addr, uint32_t ip);

static void BIPAddr_InitIPv6 (BIPAddr *addr, uint8_t *ip);

static int BIPAddr_IsRecognized (BIPAddr *addr);

static int BIPAddr_IsInvalid (BIPAddr *addr);

static int BIPAddr_Resolve (BIPAddr *addr, char *str, int noresolve) WARN_UNUSED;

static int BIPAddr_Compare (BIPAddr *addr1, BIPAddr *addr2);

/**
 * Converts an IP address to human readable form.
 *
 * @param addr IP address to convert
 * @param out destination buffer. Must be at least BIPADDR_MAX_PRINT_LEN characters long.
 */
static void BIPAddr_Print (BIPAddr *addr, char *out);

/**
 * Socket address - IP address and transport protocol port number
 */
typedef struct {
    int type;
    union {
        struct {
            uint32_t ip;
            uint16_t port;
        } ipv4;
        struct {
            uint8_t ip[16];
            uint16_t port;
        } ipv6;
    };
} BAddr;

/**
 * Initializes an invalid address.
 */
static void BAddr_InitNone (BAddr *addr);

/**
 * Initializes an IPv4 address.
 *
 * @param addr the object
 * @param ip IP address in network byte order
 * @param port port number in network byte order
 */
static void BAddr_InitIPv4 (BAddr *addr, uint32_t ip, uint16_t port);

/**
 * Initializes an IPv6 address.
 *
 * @param addr the object
 * @param ip 16-byte IP address in network byte order
 * @param port port number in network byte order
 */
static void BAddr_InitIPv6 (BAddr *addr, uint8_t *ip, uint16_t port);

/**
 * Determines whether the address is recognized.
 *
 * @param addr the object
 * @return 1 if recognized, 0 if not
 */
static int BAddr_IsRecognized (BAddr *addr);

/**
 * Determines whether the address is an invalid address.
 *
 * @param addr the object. Must be recognized according to {@link BAddr_IsRecognized}.
 * @return 1 if invalid, 0 if invalid
 **/
static int BAddr_IsInvalid (BAddr *addr);

/**
 * Returns the port number in the address.
 *
 * @param addr the object. Must be recognized according to {@link BAddr_IsRecognized},
 *             Must be an IPv4 or IPv6 address.
 * @return port number, in network byte order
 */
static uint16_t BAddr_GetPort (BAddr *addr);

/**
 * Returns the IP address in the address.
 *
 * @param addr the object. Must be recognized according to {@link BAddr_IsRecognized},
 *             Must be an IPv4 or IPv6 address.
 * @param ipaddr IP address will be returned here
 */
static void BAddr_GetIPAddr (BAddr *addr, BIPAddr *ipaddr);

/**
 * Sets the port number in the address.
 *
 * @param addr the object. Must be recognized according to {@link BAddr_IsRecognized},
 *             Must be an IPv4 or IPv6 address.
 * @param port port number, in network byte order
 */
static void BAddr_SetPort (BAddr *addr, uint16_t port);

/**
 * Converts an IP address to human readable form.
 *
 * @param addr address to convert
 * @param out destination buffer. Must be at least BADDR_MAX_PRINT_LEN characters long.
 */
static void BAddr_Print (BAddr *addr, char *out);

/**
 * Resolves an address string.
 * Format is "addr:port" for IPv4, "[addr]:port" for IPv6.
 * addr is be a numeric address or a name.
 * port is a numeric port number.
 *
 * @param addr output address
 * @param name if not NULL, the name portion of the address will be
 *             stored here
 * @param name_len if name is not NULL, the size of the name buffer
 * @param noresolve only accept numeric addresses. Avoids blocking the caller.
 * @return 1 on success, 0 on parse error
 */
static int BAddr_Parse2 (BAddr *addr, char *str, char *name, int name_len, int noresolve) WARN_UNUSED;

/**
 * Resolves an address string.
 * IPv4 input format is "a.b.c.d:p", where a.b.c.d is the IP address
 * and d is the port number.
 * IPv6 input format is "[addr]:p", where addr is an IPv6 addres in
 * standard notation and p is the port number.
 *
 * @param addr output address
 * @param name if not NULL, the name portion of the address will be
 *             stored here
 * @param name_len if name is not NULL, the size of the name buffer
 * @return 1 on success, 0 on parse error
 */
static int BAddr_Parse (BAddr *addr, char *str, char *name, int name_len) WARN_UNUSED;

void BIPAddr_InitInvalid (BIPAddr *addr)
{
    addr->type = BADDR_TYPE_NONE;
}

void BIPAddr_InitIPv4 (BIPAddr *addr, uint32_t ip)
{
    addr->type = BADDR_TYPE_IPV4;
    addr->ipv4 = ip;
}

void BIPAddr_InitIPv6 (BIPAddr *addr, uint8_t *ip)
{
    addr->type = BADDR_TYPE_IPV6;
    memcpy(addr->ipv6, ip, 16);
}

int BIPAddr_IsRecognized (BIPAddr *addr)
{
    switch (addr->type) {
        case BADDR_TYPE_NONE:
        case BADDR_TYPE_IPV4:
        case BADDR_TYPE_IPV6:
            return 1;
        default:
            return 0;
    }
}

int BIPAddr_IsInvalid (BIPAddr *addr)
{
    ASSERT(BIPAddr_IsRecognized(addr))
    
    return (addr->type == BADDR_TYPE_NONE);
}

int BIPAddr_Resolve (BIPAddr *addr, char *str, int noresolve)
{
    int len = strlen(str);
    
    char *addr_start;
    int addr_len;
    
    // determine address type
    if (len >= 1 && str[0] == '[' && str[len - 1] == ']') {
        addr->type = BADDR_TYPE_IPV6;
        addr_start = str + 1;
        addr_len = len - 2;
    } else {
        addr->type = BADDR_TYPE_IPV4;
        addr_start = str;
        addr_len = len;
    }
    
    // copy
    char addr_str[BADDR_MAX_ADDR_LEN + 1];
    if (addr_len > BADDR_MAX_ADDR_LEN) {
        return 0;
    }
    memcpy(addr_str, addr_start, addr_len);
    addr_str[addr_len] = '\0';
    
    // initialize hints
    struct addrinfo hints;
    memset(&hints, 0, sizeof(hints));
    switch (addr->type) {
        case BADDR_TYPE_IPV6:
            hints.ai_family = AF_INET6;
            break;
        case BADDR_TYPE_IPV4:
            hints.ai_family = AF_INET;
            break;
    }
    if (noresolve) {
        hints.ai_flags |= AI_NUMERICHOST;
    }
    
    // call getaddrinfo
    struct addrinfo *addrs;
    int res;
    if ((res = getaddrinfo(addr_str, NULL, &hints, &addrs)) != 0) {
        return 0;
    }
    
    // set address
    switch (addr->type) {
        case BADDR_TYPE_IPV6:
            memcpy(addr->ipv6, ((struct sockaddr_in6 *)addrs->ai_addr)->sin6_addr.s6_addr, sizeof(addr->ipv6));
            break;
        case BADDR_TYPE_IPV4:
            addr->ipv4 = ((struct sockaddr_in *)addrs->ai_addr)->sin_addr.s_addr;
            break;
    }
    
    freeaddrinfo(addrs);
    
    return 1;
}

int BIPAddr_Compare (BIPAddr *addr1, BIPAddr *addr2)
{
    ASSERT(BIPAddr_IsRecognized(addr1))
    ASSERT(BIPAddr_IsRecognized(addr2))
    
    if (addr1->type != addr2->type) {
        return 0;
    }
    
    switch (addr1->type) {
        case BADDR_TYPE_NONE:
            return 0;
        case BADDR_TYPE_IPV4:
            return (addr1->ipv4 == addr2->ipv4);
        case BADDR_TYPE_IPV6:
            return (!memcmp(addr1->ipv6, addr2->ipv6, sizeof(addr1->ipv6)));
        default:
            ASSERT(0)
            return 0;
    }
}

uint16_t BAddr_GetPort (BAddr *addr)
{
    ASSERT(BAddr_IsRecognized(addr))
    ASSERT(addr->type == BADDR_TYPE_IPV4 || addr->type == BADDR_TYPE_IPV6)
    
    switch (addr->type) {
        case BADDR_TYPE_IPV4:
            return addr->ipv4.port;
        case BADDR_TYPE_IPV6:
            return addr->ipv6.port;
        default:
            ASSERT(0)
            return 0;
    }
}

void BAddr_GetIPAddr (BAddr *addr, BIPAddr *ipaddr)
{
    ASSERT(BAddr_IsRecognized(addr))
    ASSERT(addr->type == BADDR_TYPE_IPV4 || addr->type == BADDR_TYPE_IPV6)
    
    switch (addr->type) {
        case BADDR_TYPE_IPV4:
            BIPAddr_InitIPv4(ipaddr, addr->ipv4.ip);
            return;
        case BADDR_TYPE_IPV6:
            BIPAddr_InitIPv6(ipaddr, addr->ipv6.ip);
            return;
        default:
            ASSERT(0);
    }
}

void BAddr_SetPort (BAddr *addr, uint16_t port)
{
    ASSERT(BAddr_IsRecognized(addr))
    ASSERT(addr->type == BADDR_TYPE_IPV4 || addr->type == BADDR_TYPE_IPV6)
    
    switch (addr->type) {
        case BADDR_TYPE_IPV4:
            addr->ipv4.port = port;
            break;
        case BADDR_TYPE_IPV6:
            addr->ipv6.port = port;
            break;
        default:
            ASSERT(0);
    }
}

struct _BAddr_ipv6_addr
{
    uint16_t addr[8];
} __attribute__((packed));

void BIPAddr_Print (BIPAddr *addr, char *out)
{
    switch (addr->type) {
        case BADDR_TYPE_NONE:
            sprintf(out, "(none)");
            break;
        case BADDR_TYPE_IPV4:
            sprintf(out, "%"PRIu8".%"PRIu8".%"PRIu8".%"PRIu8,
                *((uint8_t *)&addr->ipv4 + 0),
                *((uint8_t *)&addr->ipv4 + 1),
                *((uint8_t *)&addr->ipv4 + 2),
                *((uint8_t *)&addr->ipv4 + 3)
            );
            break;
        case BADDR_TYPE_IPV6: {
            struct _BAddr_ipv6_addr *s = (struct _BAddr_ipv6_addr *)addr->ipv6;
            sprintf(out,
                "%"PRIx16":%"PRIx16":%"PRIx16":%"PRIx16":"
                "%"PRIx16":%"PRIx16":%"PRIx16":%"PRIx16,
                ntoh16(s->addr[0]),
                ntoh16(s->addr[1]),
                ntoh16(s->addr[2]),
                ntoh16(s->addr[3]),
                ntoh16(s->addr[4]),
                ntoh16(s->addr[5]),
                ntoh16(s->addr[6]),
                ntoh16(s->addr[7])
            );
        } break;
        default:
            ASSERT(0);
    }
}

void BAddr_InitNone (BAddr *addr)
{
    addr->type = BADDR_TYPE_NONE;
}

void BAddr_InitIPv4 (BAddr *addr, uint32_t ip, uint16_t port)
{
    addr->type = BADDR_TYPE_IPV4;
    addr->ipv4.ip = ip;
    addr->ipv4.port = port;
}

void BAddr_InitIPv6 (BAddr *addr, uint8_t *ip, uint16_t port)
{
    addr->type = BADDR_TYPE_IPV6;
    memcpy(addr->ipv6.ip, ip, 16);
    addr->ipv6.port = port;
}

int BAddr_IsRecognized (BAddr *addr)
{
    switch (addr->type) {
        case BADDR_TYPE_NONE:
        case BADDR_TYPE_IPV4:
        case BADDR_TYPE_IPV6:
            return 1;
        default:
            return 0;
    }
}

int BAddr_IsInvalid (BAddr *addr)
{
    ASSERT(BAddr_IsRecognized(addr))
    
    return (addr->type == BADDR_TYPE_NONE);
}

void BAddr_Print (BAddr *addr, char *out)
{
    ASSERT(BAddr_IsRecognized(addr))
    
    BIPAddr ipaddr;
    
    switch (addr->type) {
        case BADDR_TYPE_NONE:
            sprintf(out, "(none)");
            break;
        case BADDR_TYPE_IPV4:
            BIPAddr_InitIPv4(&ipaddr, addr->ipv4.ip);
            BIPAddr_Print(&ipaddr, out);
            sprintf(out + strlen(out), ":%"PRIu16, ntoh16(addr->ipv4.port));
            break;
        case BADDR_TYPE_IPV6:
            BIPAddr_InitIPv6(&ipaddr, addr->ipv6.ip);
            BIPAddr_Print(&ipaddr, out);
            sprintf(out + strlen(out), ":%"PRIu16, ntoh16(addr->ipv6.port));
            break;
        default:
            ASSERT(0);
    }
}

int BAddr_Parse2 (BAddr *addr, char *str, char *name, int name_len, int noresolve)
{
    BAddr result;
    
    int len = strlen(str);
    if (len < 1 || len > 1000) {
        return 0;
    }
    
    int addr_start;
    int addr_len;
    int port_start;
    int port_len;
    
    // leading '[' indicates an IPv6 address
    if (str[0] == '[') {
        addr->type = BADDR_TYPE_IPV6;
        // find ']'
        int i=1;
        while (i < len && str[i] != ']') i++;
        if (i >= len) {
            return 0;
        }
        addr_start = 1;
        addr_len = i - addr_start;
        // follows ':' and port number
        if (i + 1 >= len || str[i + 1] != ':') {
            return 0;
        }
        port_start = i + 2;
        port_len = len - port_start;
    }
    // otherwise it's an IPv4 address
    else {
        addr->type = BADDR_TYPE_IPV4;
        // find ':'
        int i=0;
        while (i < len && str[i] != ':') i++;
        if (i >= len) {
            return 0;
        }
        addr_start = 0;
        addr_len = i - addr_start;
        port_start = i + 1;
        port_len = len - port_start;
    }
    
    // copy address and port to zero-terminated buffers
    
    char addr_str[128];
    if (addr_len >= sizeof(addr_str)) {
        return 0;
    }
    memcpy(addr_str, str + addr_start, addr_len);
    addr_str[addr_len] = '\0';
    
    char port_str[6];
    if (port_len >= sizeof(port_str)) {
        return 0;
    }
    memcpy(port_str, str + port_start, port_len);
    port_str[port_len] = '\0';
    
    // parse port
    char *err;
    long int conv_res = strtol(port_str, &err, 10);
    if (port_str[0] == '\0' || *err != '\0') {
        return 0;
    }
    if (conv_res < 0 || conv_res > UINT16_MAX) {
        return 0;
    }
    uint16_t port = conv_res;
    port = hton16(port);
    
    // initialize hints
    struct addrinfo hints;
    memset(&hints, 0, sizeof(hints));
    switch (addr->type) {
        case BADDR_TYPE_IPV6:
            hints.ai_family = AF_INET6;
            break;
        case BADDR_TYPE_IPV4:
            hints.ai_family = AF_INET;
            break;
    }
    if (noresolve) {
        hints.ai_flags |= AI_NUMERICHOST;
    }
    
    // call getaddrinfo
    struct addrinfo *addrs;
    int res;
    if ((res = getaddrinfo(addr_str, NULL, &hints, &addrs)) != 0) {
        return 0;
    }
    
    // set address
    switch (addr->type) {
        case BADDR_TYPE_IPV6:
            memcpy(addr->ipv6.ip, ((struct sockaddr_in6 *)addrs->ai_addr)->sin6_addr.s6_addr, sizeof(addr->ipv6.ip));
            addr->ipv6.port = port;
            break;
        case BADDR_TYPE_IPV4:
            addr->ipv4.ip = ((struct sockaddr_in *)addrs->ai_addr)->sin_addr.s_addr;
            addr->ipv4.port = port;
            break;
    }
    
    freeaddrinfo(addrs);
    
    if (name) {
        snprintf(name, name_len, "%s", addr_str);
    }
    
    return 1;
}

int BAddr_Parse (BAddr *addr, char *str, char *name, int name_len)
{
    return BAddr_Parse2(addr, str, name, name_len, 0);
}

#endif