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tunnelkit/Sources/CTunnelKitCore/RoutingTableEntry.m

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//
// RoutingTableEntry.m
// TunnelKit
//
// Created by Davide De Rosa on 4/30/19.
// Copyright (c) 2022 Davide De Rosa. All rights reserved.
//
// https://github.com/passepartoutvpn
//
// This file is part of TunnelKit.
//
// TunnelKit is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// TunnelKit 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 TunnelKit. If not, see <http://www.gnu.org/licenses/>.
//
#import <arpa/inet.h>
#import <netdb.h>
#import <net/if.h>
#import "route.h"
#import "RoutingTableEntry.h"
#define ASSERT_PRINTF(r) NSCAssert(r >= 0, @"*printf() failed")
#define ASSERT_GETNAMEINFO(r) NSCAssert(r == 0, @"getnameinfo() failed")
// adapted from: https://github.com/jianpx/ios-cabin
#define ROUNDUP(a) ((a) > 0 ? (1 + (((a) - 1) | (sizeof(uint32_t) - 1))) : sizeof(uint32_t))
typedef union {
uint32_t dummy;
struct sockaddr u_sa;
u_short u_data[128];
} sa_u;
static uint32_t RoutingTableEntryAddress4(NSString *string);
static NSData *RoutingTableEntryAddress6(NSString *string);
static NSString *RoutingTableEntryName(struct sockaddr *sa, struct sockaddr *mask, int flags);
#pragma mark -
@interface RoutingTableEntry ()
@property (nonatomic, assign) BOOL isIPv6;
@property (nonatomic, copy) NSString *network;
@property (nonatomic, assign) NSInteger prefix;
@property (nonatomic, copy) NSString *gateway;
@property (nonatomic, copy) NSString *networkInterface;
@end
@implementation RoutingTableEntry
- (instancetype)initWithNetwork:(NSString *)network prefix:(NSInteger)prefix gateway:(NSString *)gateway networkInterface:(NSString *)networkInterface
{
if (!(self = [super init])) {
return nil;
}
self.network = network;
self.prefix = prefix;
self.gateway = gateway;
self.networkInterface = networkInterface;
return self;
}
- (instancetype)initWithIPv4Network:(NSString *)network gateway:(NSString *)gateway networkInterface:(NSString *)networkInterface
{
NSInteger prefix = 0;
NSArray<NSString *> *networkComps = [network componentsSeparatedByString:@"/"];
network = networkComps.firstObject;
if (networkComps.count == 2) {
prefix = [networkComps.lastObject integerValue];
NSAssert(prefix >= 0 && prefix <= 32, @"IPv4 prefix must lie in [0..32]");
} else {
prefix = 32;
}
NSMutableArray<NSString *> *groups = [[network componentsSeparatedByString:@"."] mutableCopy];
if (![network isEqualToString:@"default"]) {
if (prefix == 32) {
prefix = 8 * groups.count;
}
for (NSInteger i = groups.count; i < 4; ++i) {
[groups addObject:@"0"];
}
network = [groups componentsJoinedByString:@"."];
}
if (!(self = [self initWithNetwork:network prefix:prefix gateway:gateway networkInterface:networkInterface])) {
return nil;
}
self.isIPv6 = NO;
return self;
}
- (instancetype)initWithIPv6Network:(NSString *)network gateway:(NSString *)gateway networkInterface:(NSString *)networkInterface
{
NSInteger prefix = 0;
NSArray<NSString *> *networkComps = [network componentsSeparatedByString:@"/"];
network = networkComps.firstObject;
if (networkComps.count == 2) {
prefix = [networkComps.lastObject integerValue];
NSAssert(prefix >= 0 && prefix <= 128, @"IPv6 prefix must lie in [0..128]");
} else {
prefix = 128;
}
network = [[network componentsSeparatedByString:@"%"] firstObject];
gateway = [[gateway componentsSeparatedByString:@"%"] firstObject];
if (!(self = [self initWithNetwork:network prefix:prefix gateway:gateway networkInterface:networkInterface])) {
return nil;
}
self.isIPv6 = YES;
return self;
}
- (instancetype)initWithRTM:(const struct rt_msghdr2 *)rtm
{
NSParameterAssert(rtm);
NSString *network;
NSString *gateway;
NSString *networkInterface;
struct sockaddr *rti_info[RTAX_MAX];
struct sockaddr *sa = (struct sockaddr *)(rtm + 1);
for (int i = 0; i < RTAX_MAX; ++i) {
if (rtm->rtm_addrs & (1 << i)) {
rti_info[i] = sa;
sa = (struct sockaddr *)(ROUNDUP(sa->sa_len) + (char *)sa);
} else {
rti_info[i] = NULL;
}
}
// network
sa_u destinationStruct, destinationNetmask;
bzero(&destinationStruct, sizeof(destinationStruct));
if (rtm->rtm_addrs & RTA_DST) {
bcopy(rti_info[RTAX_DST], &destinationStruct, rti_info[RTAX_DST]->sa_len);
}
bzero(&destinationNetmask, sizeof(destinationNetmask));
if (rtm->rtm_addrs & RTA_NETMASK) {
bcopy(rti_info[RTAX_NETMASK], &destinationNetmask, rti_info[RTAX_NETMASK]->sa_len);
}
network = RoutingTableEntryName(&destinationStruct.u_sa, &destinationNetmask.u_sa, rtm->rtm_flags);
// gateway
sa_u gatewayStruct;
bzero(&gatewayStruct, sizeof(gatewayStruct));
if (rtm->rtm_addrs & RTA_GATEWAY) {
bcopy(rti_info[RTAX_GATEWAY], &gatewayStruct, rti_info[RTAX_GATEWAY]->sa_len);
}
gateway = RoutingTableEntryName(rti_info[RTAX_GATEWAY], NULL, RTF_HOST);
// network interface
char networkInterfaceStr[IF_NAMESIZE];
const char *networkInterfaceName = if_indextoname(rtm->rtm_index, networkInterfaceStr);
if (networkInterfaceName) {
networkInterface = [NSString stringWithCString:networkInterfaceName encoding:NSASCIIStringEncoding];
}
if (rti_info[RTAX_DST]->sa_family == AF_INET6) {
return [self initWithIPv6Network:network gateway:gateway networkInterface:networkInterface];
} else {
return [self initWithIPv4Network:network gateway:gateway networkInterface:networkInterface];
}
}
- (NSString *)networkMask
{
struct in_addr mask;
mask.s_addr = htonl(~((1 << (32 - self.prefix)) - 1));
const char *address = inet_ntoa(mask);
return [NSString stringWithCString:address encoding:NSASCIIStringEncoding];
}
- (BOOL)isDefault
{
return [self.network isEqualToString:@"default"];
}
- (BOOL)matchesDestination:(NSString *)destination
{
NSParameterAssert(destination);
if ([self isDefault]) {
return YES;
}
if (self.isIPv6) {
NSData *networkAddress = RoutingTableEntryAddress6(self.network);
NSData *destinationAddress = RoutingTableEntryAddress6(destination);
if (!networkAddress || !destinationAddress) {
return NO;
}
// NSLog(@"network: %@ = %@", networkAddress, self.network);
// NSLog(@"destination: %@ = %@", destinationAddress, destination);
const uint8_t *networkPtr = networkAddress.bytes;
const uint8_t *destinationPtr = destinationAddress.bytes;
NSInteger leftBits = self.prefix;
// NSLog(@"\tprefix = %u", (int)self.prefix);
for (NSInteger i = 0; leftBits > 0; ++i) {
uint8_t networkMask;
if (leftBits >= 8) {
networkMask = 0xff;
} else {
networkMask = ~((1 << (8 - leftBits)) - 1);
}
// NSLog(@"\tnetworkMask[%u] = %x", (int)i, networkMask);
if (((networkPtr[i] ^ destinationPtr[i]) & networkMask) != 0) {
return NO;
}
leftBits -= 8;
}
// NSLog(@"\tMATCH");
return YES;
}
else {
const uint32_t networkAddress = RoutingTableEntryAddress4(self.network);
const uint32_t destinationAddress = RoutingTableEntryAddress4(destination);
if ((networkAddress == UINT32_MAX) || (destinationAddress == UINT32_MAX)) {
return NO;
}
const uint32_t networkMask = ~((1 << (32 - self.prefix)) - 1);
// NSLog(@"network: %x = %@", networkAddress, self.network);
// NSLog(@"destination: %x = %@", destinationAddress, destination);
// NSLog(@"mask: %x", networkMask);
return ((networkAddress ^ destinationAddress) & networkMask) == 0;
}
}
- (nullable NSArray<RoutingTableEntry *> *)partitioned
{
NSMutableArray<RoutingTableEntry *> *segments = [[NSMutableArray alloc] init];
const int halfPrefix = (int)(self.prefix + 1);
if (self.isIPv6) {
if (self.prefix == 128) {
NSLog(@"Can't partition single IPv6");
return @[self, self];
}
struct in6_addr saddr1, saddr2;
char addr[INET6_ADDRSTRLEN];
NSData *addressData = RoutingTableEntryAddress6(self.network);
if (!addressData) {
return nil;
}
memcpy(&saddr1, addressData.bytes, addressData.length);
NSMutableData *addressData2 = [addressData mutableCopy];
uint8_t *addressBytes2 = (uint8_t *)addressData2.bytes;
const uint8_t mask2 = 1 << ((8 - halfPrefix % 8) % 8);
addressBytes2[(halfPrefix - 1) / 8] |= mask2;
memcpy(&saddr2, addressData2.bytes, addressData2.length);
inet_ntop(AF_INET6, &saddr1, addr, INET6_ADDRSTRLEN);
NSString *network1 = [NSString stringWithFormat:@"%s/%d", addr, halfPrefix];
inet_ntop(AF_INET6, &saddr2, addr, INET6_ADDRSTRLEN);
NSString *network2 = [NSString stringWithFormat:@"%s/%d", addr, halfPrefix];
[segments addObject:[[RoutingTableEntry alloc] initWithIPv6Network:network1 gateway:self.gateway networkInterface:self.networkInterface]];
[segments addObject:[[RoutingTableEntry alloc] initWithIPv6Network:network2 gateway:self.gateway networkInterface:self.networkInterface]];
} else {
if (self.prefix == 32) {
NSLog(@"Can't partition single IPv4");
return @[self, self];
}
struct in_addr saddr1, saddr2;
const uint32_t address = RoutingTableEntryAddress4(self.network);
if (address == UINT32_MAX) {
return nil;
}
saddr1.s_addr = htonl(address);
saddr2.s_addr = htonl(address | (1 << (32 - halfPrefix)));
// XXX: inet_ntoa returns pointer to static variable, copy before next call
const char *address1 = inet_ntoa(saddr1);
NSString *network1 = [NSString stringWithFormat:@"%s/%d", address1, halfPrefix];
const char *address2 = inet_ntoa(saddr2);
NSString *network2 = [NSString stringWithFormat:@"%s/%d", address2, halfPrefix];
[segments addObject:[[RoutingTableEntry alloc] initWithIPv4Network:network1 gateway:self.gateway networkInterface:self.networkInterface]];
[segments addObject:[[RoutingTableEntry alloc] initWithIPv4Network:network2 gateway:self.gateway networkInterface:self.networkInterface]];
}
return segments;
}
- (NSString *)description
{
return [NSString stringWithFormat:@"{%@/%ld -> %@ via %@}", self.network, self.prefix, self.gateway ?: @"nil", self.networkInterface];
}
@end
#pragma mark -
static char *netname(uint32_t in, uint32_t mask);
static char *netname6(struct sockaddr_in6 *sa6, struct sockaddr *sam);
static char *routename(uint32_t in);
static char *routename6(struct sockaddr_in6 *sa6);
static uint32_t forgemask(uint32_t a);
static void domask(char *dst, size_t dstsize, uint32_t addr, uint32_t mask);
static void trimdomain(char *cp);
static inline uint32_t RoutingTableEntryAddress4(NSString *string)
{
struct in_addr addr;
if (inet_pton(AF_INET, [string cStringUsingEncoding:NSASCIIStringEncoding], &addr) <= 0) {
return UINT32_MAX;
}
return CFSwapInt32BigToHost(addr.s_addr);
}
static inline NSData *RoutingTableEntryAddress6(NSString *string)
{
struct in6_addr addr;
if (inet_pton(AF_INET6, [string cStringUsingEncoding:NSASCIIStringEncoding], &addr) <= 0) {
return nil;
}
NSMutableData *data = [[NSMutableData alloc] initWithLength:16];
memcpy(data.mutableBytes, (void *)&addr, data.length);
return data;
}
static NSString *RoutingTableEntryName(struct sockaddr *sa, struct sockaddr *mask, int flags)
{
char *cp = NULL;
switch (sa->sa_family) {
case AF_INET: {
struct sockaddr_in *sin = (struct sockaddr_in *)sa;
if ((sin->sin_addr.s_addr == INADDR_ANY) && mask && (ntohl(((struct sockaddr_in *)mask)->sin_addr.s_addr) == 0L || mask->sa_len == 0)) {
cp = "default";
} else if (flags & RTF_HOST) {
cp = routename(sin->sin_addr.s_addr);
} else if (mask) {
cp = netname(sin->sin_addr.s_addr, ntohl(((struct sockaddr_in *)mask)->sin_addr.s_addr));
} else {
cp = netname(sin->sin_addr.s_addr, 0L);
}
break;
}
case AF_INET6: {
struct sockaddr_in6 *sa6 = (struct sockaddr_in6 *)sa;
struct in6_addr *in6 = &sa6->sin6_addr;
/*
* XXX: This is a special workaround for KAME kernels.
* sin6_scope_id field of SA should be set in the future.
*/
if (IN6_IS_ADDR_LINKLOCAL(in6) ||
IN6_IS_ADDR_MC_NODELOCAL(in6) ||
IN6_IS_ADDR_MC_LINKLOCAL(in6)) {
/* XXX: override is ok? */
sa6->sin6_scope_id = (u_int32_t)ntohs(*(u_short *)&in6->s6_addr[2]);
*(u_short *)&in6->s6_addr[2] = 0;
}
if (flags & RTF_HOST) {
cp = routename6(sa6);
} else if (mask) {
cp = netname6(sa6, mask);
} else {
cp = netname6(sa6, NULL);
}
break;
}
default:
break;
}
if (!cp) {
return nil;
}
return [NSString stringWithCString:cp encoding:NSASCIIStringEncoding];
}
char *routename(uint32_t in)
{
static char line[MAXHOSTNAMELEN];
#define C(x) ((x) & 0xff)
in = ntohl(in);
ASSERT_PRINTF(snprintf(line, sizeof(line), "%u.%u.%u.%u", C(in >> 24), C(in >> 16), C(in >> 8), C(in)));
return (line);
}
char *routename6(struct sockaddr_in6 *sa6)
{
static char line[MAXHOSTNAMELEN];
int flag = NI_NUMERICHOST;
/* use local variable for safety */
struct sockaddr_in6 sa6_local = {sizeof(sa6_local), AF_INET6, };
sa6_local.sin6_addr = sa6->sin6_addr;
sa6_local.sin6_scope_id = sa6->sin6_scope_id;
ASSERT_GETNAMEINFO(getnameinfo((struct sockaddr *)&sa6_local, sa6_local.sin6_len, line, sizeof(line), NULL, 0, flag));
return line;
}
/*
* Return the name of the network whose address is given.
* The address is assumed to be that of a net or subnet, not a host.
*/
char *netname(uint32_t in, uint32_t mask)
{
char *cp = 0;
static char line[MAXHOSTNAMELEN];
struct netent *np = 0;
uint32_t net, omask, dmask;
uint32_t i;
i = ntohl(in);
dmask = forgemask(i);
omask = mask;
// if (!nflag && i) {
if (i) {
net = i & dmask;
if (!(np = getnetbyaddr(i, AF_INET)) && net != i)
np = getnetbyaddr(net, AF_INET);
if (np) {
cp = np->n_name;
trimdomain(cp);
}
}
if (cp) {
strncpy(line, cp, sizeof(line) - 1);
} else {
switch (dmask) {
case IN_CLASSA_NET:
if ((i & IN_CLASSA_HOST) == 0) {
ASSERT_PRINTF(snprintf(line, sizeof(line), "%u", C(i >> 24)));
break;
}
/* FALLTHROUGH */
case IN_CLASSB_NET:
if ((i & IN_CLASSB_HOST) == 0) {
ASSERT_PRINTF(snprintf(line, sizeof(line), "%u.%u", C(i >> 24), C(i >> 16)));
break;
}
/* FALLTHROUGH */
case IN_CLASSC_NET:
if ((i & IN_CLASSC_HOST) == 0) {
ASSERT_PRINTF(snprintf(line, sizeof(line), "%u.%u.%u", C(i >> 24), C(i >> 16), C(i >> 8)));
break;
}
/* FALLTHROUGH */
default:
ASSERT_PRINTF(snprintf(line, sizeof(line), "%u.%u.%u.%u", C(i >> 24), C(i >> 16), C(i >> 8), C(i)));
break;
}
}
domask(line + strlen(line), sizeof(line) - strlen(line), i, omask);
return (line);
}
char *netname6(struct sockaddr_in6 *sa6, struct sockaddr *sam)
{
char host[MAXHOSTNAMELEN];
static char line[MAXHOSTNAMELEN + 10];
u_char *lim;
int masklen, illegal = 0, flag = NI_NUMERICHOST;
struct in6_addr *mask = sam ? &((struct sockaddr_in6 *)sam)->sin6_addr : 0;
if (sam && sam->sa_len == 0) {
masklen = 0;
} else if (mask) {
u_char *p = (u_char *)mask;
for (masklen = 0, lim = p + 16; p < lim; p++) {
switch (*p) {
case 0xff:
masklen += 8;
break;
case 0xfe:
masklen += 7;
break;
case 0xfc:
masklen += 6;
break;
case 0xf8:
masklen += 5;
break;
case 0xf0:
masklen += 4;
break;
case 0xe0:
masklen += 3;
break;
case 0xc0:
masklen += 2;
break;
case 0x80:
masklen += 1;
break;
case 0x00:
break;
default:
illegal ++;
break;
}
}
if (illegal)
fprintf(stderr, "illegal prefixlen\n");
} else {
masklen = 128;
}
if (masklen == 0 && IN6_IS_ADDR_UNSPECIFIED(&sa6->sin6_addr)) {
return("default");
}
ASSERT_GETNAMEINFO(getnameinfo((struct sockaddr *)sa6, sa6->sin6_len, host, sizeof(host), NULL, 0, flag));
if (masklen > 0) {
ASSERT_PRINTF(sprintf(line, "%s/%u", host, masklen));
} else {
ASSERT_PRINTF(sprintf(line, "%s", host));
}
return line;
}
uint32_t forgemask(uint32_t a)
{
uint32_t m;
if (IN_CLASSA(a))
m = IN_CLASSA_NET;
else if (IN_CLASSB(a))
m = IN_CLASSB_NET;
else
m = IN_CLASSC_NET;
return (m);
}
void domask(char *dst, size_t dstsize, uint32_t addr, uint32_t mask)
{
int b, i;
if (!mask || (forgemask(addr) == mask)) {
*dst = '\0';
return;
}
i = 0;
for (b = 0; b < 32; b++) {
if (mask & (1 << b)) {
int bb;
i = b;
for (bb = b+1; bb < 32; bb++)
if (!(mask & (1 << bb))) {
i = -1; /* noncontig */
break;
}
break;
}
}
if (i == -1) {
ASSERT_PRINTF(snprintf(dst, dstsize, "&0x%x", mask));
} else {
ASSERT_PRINTF(snprintf(dst, dstsize, "/%d", 32-i));
}
}
void trimdomain(char *cp)
{
static char domain[MAXHOSTNAMELEN + 1];
static int first = 1;
char *s;
if (first) {
first = 0;
if (gethostname(domain, MAXHOSTNAMELEN) == 0 &&
(s = strchr(domain, '.')))
(void) strcpy(domain, s + 1);
else
domain[0] = 0;
}
if (domain[0]) {
while ((cp = strchr(cp, '.'))) {
if (!strcasecmp(cp + 1, domain)) {
*cp = 0; /* hit it */
break;
} else {
cp++;
}
}
}
}
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