From 335dbd863825dd55ed19b1e6bbadc597bc28083f Mon Sep 17 00:00:00 2001
From: Dimitri Papadopoulos
 <3234522+DimitriPapadopoulos@users.noreply.github.com>
Date: Fri, 18 Dec 2020 15:59:30 +0100
Subject: [PATCH] Add patch provided by @rain2fog in #801

---
 tun.patch | 1241 +++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 1241 insertions(+)
 create mode 100644 tun.patch

diff --git a/tun.patch b/tun.patch
new file mode 100644
index 00000000..77052302
--- /dev/null
+++ b/tun.patch
@@ -0,0 +1,1241 @@
+diff --git a/src/http.c b/src/http.c
+index e2dbb24..b65f622 100644
+--- a/src/http.c
++++ b/src/http.c
+@@ -824,6 +824,11 @@ static int parse_xml_config(struct tunnel *tunnel, const char *buffer)
+ 	if (!gateway)
+ 		log_warn("No gateway address, using interface for routing\n");
+ 
++	if (tunnel->use_tun) {
++		tunnel->ipv4.ip_addr.s_addr = inet_addr(gateway);
++		tunnel->ipv4.peer_addr.s_addr = inet_addr("192.0.2.1");
++	}
++
+ 	// The dns search string
+ 	val = buffer;
+ 	while ((val = xml_find('<', "dns", val, 2))) {
+diff --git a/src/io.c b/src/io.c
+index 577623b..86600c5 100644
+--- a/src/io.c
++++ b/src/io.c
+@@ -35,6 +35,7 @@
+ #include <unistd.h>
+ #include <arpa/inet.h>
+ #include <netinet/tcp.h>
++#include <net/if_ppp.h>
+ 
+ #include <errno.h>
+ #include <signal.h>
+@@ -175,6 +176,845 @@ static os_semaphore_t sem_pppd_ready;
+ static os_semaphore_t sem_if_config;
+ static os_semaphore_t sem_stop_io;
+ 
++struct lcp_header {
++	uint8_t   code;
++#define LCP_CONF_REQUEST    1
++#define LCP_CONF_ACK        2
++#define LCP_CONF_NAK        3
++#define LCP_CONF_REJECT     4
++#define LCP_TERM_REQUEST    5
++#define LCP_TERM_ACK        6
++#define LCP_CODE_REJECT     7
++#define LCP_PROT_REJECT     8
++#define LCP_ECHO_REQUEST    9
++#define LCP_ECHO_REPLY      10
++#define LCP_DISCARD         11
++	uint8_t   id;
++	uint16_t length;
++};
++
++const char *lcp_code_name[] = {
++	"",
++	"Configure-Request",
++	"Configure-Ack",
++	"Configure-Nak",
++	"Configure-Reject",
++	"Terminate-Request",
++	"Terminate-Ack",
++	"Code-Reject",
++	"Protocol-Reject",
++	"Echo-Request",
++	"Echo-Reply",
++	"Discard-Request",
++};
++struct lcp_conf_request {
++	struct lcp_header header;
++};
++struct conf_option {
++	uint8_t   type;
++#define LCP_COPT_MRU      1
++#define LCP_COPT_ACCM     2
++#define LCP_COPT_AUTH     3
++#define LCP_COPT_QUALITY  4
++#define LCP_COPT_MAGIC    5
++#define LCP_COPT_PFC      7
++#define LCP_COPT_ACFC     8
++	uint8_t   length;
++	uint8_t   data[];
++};
++static void *co_data(struct conf_option *co)
++{
++	return co->data;
++}
++
++struct conf_option_list {
++	struct conf_option *head;
++	struct conf_option *tail;
++};
++
++struct lcp_option_conf {
++	int flag;
++#define LCP_OF_VALID   0x10000
++	int len;
++	const char *name;
++};
++int default_mru = 1534;
++const struct lcp_option_conf lcp_valid_options[256] = {
++	[0] = {           0, 0, "RESERVED",                   },
++	[1] = {LCP_OF_VALID, 4, "MRU",                        },		/* RFC 1661 */
++	[2] = {LCP_OF_VALID, 6, "Async-Control-Character-Map",},		/* RFC 1172 */
++	[3] = {LCP_OF_VALID, 4, "Auth-Protocol",              },
++	[4] = {LCP_OF_VALID, 4, "Quality-Protocol",           },
++	[5] = {LCP_OF_VALID, 6, "Magic-Num",                  },
++	[6] = {LCP_OF_VALID, 6, "Link-Quality-Monitoring",    },		/* RFC 1172 */
++	[7] = {LCP_OF_VALID, 2, "Protocol-Field-Comp",        },
++	[8] = {LCP_OF_VALID, 2, "Addr&Ctrl-Field-Comp",       },          
++};
++struct lcp_option_value {
++	int flag;
++#define LCP_OF_DEFAULT 0x20000
++#define LCP_OF_DISABLE 0x00100
++#define LCP_OF_LINK    0x000FF
++	int len;
++	union {
++		int boolean;
++		int number;
++	} u;
++	void *extra;
++};
++int magic_seed = 0x64696E67;
++/*
++struct conf_option lcp_default[256] = {
++	[1] = {LCP_OF_DEFAULT, {.number = 1500}, },
++	[2] = {LCP_OF_DEFAULT, {.number = 0xFFFFFFFF}, },
++	[3] = {LCP_OF_DEFAULT | LCP_OF_DISABLE, },
++	[4] = {LCP_OF_DEFAULT | LCP_OF_DISABLE, },
++	[5] = {LCP_OF_DEFAULT | LCP_OF_DISABLE, },
++	[6] = {LCP_OF_DEFAULT | LCP_OF_DISABLE, },
++	[7] = {LCP_OF_DEFAULT | LCP_OF_DISABLE, },
++	[8] = {LCP_OF_DEFAULT | LCP_OF_DISABLE, },
++};
++*/
++struct conf_option *lcp_self[256] = {
++	NULL,
++};
++struct conf_option *lcp_peer[256] = {
++	NULL,
++};
++
++static int lcp_id = 0;
++int conf_option_get(struct conf_option **options, int type, void *data, int len)
++{
++	struct conf_option *opt = options[type];
++	if (opt != NULL) {
++		int copy = opt->length - 2;
++		if (copy > len) {
++			copy = len;
++		}
++		memcpy(data, opt->data, copy);
++		return 0;
++	}
++	return -1;
++}
++int conf_option_set(struct conf_option **options, int type, int len, void *data)
++{
++	struct conf_option *opt = options[type];
++	if (len == 0) {
++		options[type] = NULL;
++		free(opt);
++		return 0;
++	}
++
++	if (opt == NULL) {
++		opt = malloc(len);
++	} else if (opt->length != len) {
++		opt = realloc(opt, len);
++	}
++	if (opt != NULL) {
++		options[type] = opt;
++		opt->type = type;
++		opt->length = len;
++		if (len > 2) {
++			memcpy(opt->data, data, len - 2);
++		}
++	}
++	return (opt == NULL) ? -1 : 0;
++}
++struct conf_option *conf_option_init(struct conf_option_list *optlist)
++{
++	int header = sizeof(struct lcp_header) + sizeof(uint16_t);
++	optlist->head = malloc(header + default_mru);
++	if (optlist->head) {
++		memset(optlist->head, 0, header + default_mru);
++		optlist->head = (struct conf_option *)(((uint8_t *)optlist->head) + header);
++		optlist->tail = optlist->head;
++	}
++	return optlist->head;
++}
++int conf_option_encode(struct conf_option_list *optlist, int type, int len, void *data)
++{
++	optlist->tail->type = type;
++	optlist->tail->length = len;
++	if (len > 2) {
++		memcpy(optlist->tail->data, data, len - 2);
++	}
++	optlist->tail = (struct conf_option *)(optlist->tail->data + len - 2);
++	return 0;
++}
++int conf_option_length(struct conf_option_list *optlist)
++{
++	int len = 0;
++	if (optlist) {
++		len = (uint8_t *)optlist->tail - (uint8_t *)optlist->head;
++	}
++	return len;
++}
++int conf_option_free(struct conf_option_list *optlist)
++{
++	if (optlist->head != NULL) {
++		int header = sizeof(struct lcp_header) + sizeof(uint16_t);
++		free((uint8_t *)optlist->head - header);
++		optlist->head = optlist->tail = NULL;
++	}
++	return 0;
++}
++int lcp_option_send(struct tunnel *tunnel, int id, int code, struct conf_option_list *optlist, int force)
++{
++	int ret = -1;
++	if (optlist && optlist->head) {
++		uint8_t *head = (uint8_t *)optlist->head;
++		struct lcp_header *header = ((struct lcp_header *)head) - 1;
++		unsigned short *ppp_type = ((unsigned short *)header) - 1;
++		int len = conf_option_length(optlist);
++		int hdrlen = sizeof(struct lcp_header) + sizeof(uint16_t);
++
++		if (len > 0 || force) {
++			ssize_t pktsize;
++			struct ppp_packet *packet = NULL;
++
++			*ppp_type = htons(PPP_LCP);
++			header->code = code;
++			header->id = id ? id : lcp_id ++;
++			header->length = htons(len + sizeof(*header));
++
++			pktsize = hdrlen + len;
++			packet = malloc(sizeof(*packet) + 6 + pktsize);
++			if (packet == NULL) {
++				goto out;
++			}
++			packet->len = pktsize;
++			memcpy(pkt_data(packet), ppp_type, pktsize);
++
++			log_debug("%s ---> gateway (%lu bytes)\n", PPP_DAEMON,
++				  packet->len);
++#if HAVE_USR_SBIN_PPPD
++			log_packet("pppd:   ", packet->len, pkt_data(packet));
++#else
++			log_packet("ppp:   ", packet->len, pkt_data(packet));
++#endif
++			pool_push(&tunnel->pty_to_ssl_pool, packet);
++		}
++		ret = 0;
++	}
++
++out:
++	return ret;
++}
++int conf_request(struct tunnel *tunnel)
++{
++	int ret = 0;
++	struct conf_option_list request;
++	uint16_t mru = htons(default_mru);
++	int magic = htonl(magic_seed);
++	conf_option_init(&request);
++	conf_option_encode(&request, LCP_COPT_MRU, 4, &mru);
++	conf_option_encode(&request, LCP_COPT_MAGIC, 6, &magic);
++	ret = lcp_option_send(tunnel, 0, LCP_CONF_REQUEST, &request, 1);
++	conf_option_free(&request);
++	return ret;
++}
++int lcp_packet(struct tunnel *tunnel, void *packet, int len)
++{
++	struct lcp_header *header = packet;
++
++	log_debug("packet %s\n", lcp_code_name[header->code]);
++	switch (header->code) {
++	case LCP_CONF_REQUEST:
++	{
++		int olen = ntohs(header->length);
++		struct conf_option *co = NULL;
++		struct conf_option_list ack;
++		struct conf_option_list nack;
++		struct conf_option_list reject;
++		conf_option_init(&ack);
++		conf_option_init(&nack);
++		conf_option_init(&reject);
++		olen -= sizeof(struct lcp_header);
++		co = (struct conf_option *)(header + 1);
++		while (olen > 0) {
++			char buff[128];
++			char *p = buff;
++			p += sprintf(p, "option %s: ", lcp_valid_options[co->type].name);
++			switch (co->type) {
++			case LCP_COPT_ACCM:
++				p += sprintf(p, "%x", ntohl(*(uint32_t *)co_data(co)));
++				conf_option_set(lcp_peer, co->type, co->length, co_data(co));
++				conf_option_encode(&ack, co->type, co->length, co_data(co));
++				break;
++			case LCP_COPT_AUTH:
++				switch (ntohs(*(uint16_t *)co_data(co))) {
++				case PPP_CHAP:
++				{
++					struct {
++						uint16_t chap;
++						uint8_t  algo;
++					} *payload = (typeof(*payload) *)co_data(co);
++					p += sprintf(p, "CHAP %d", payload->algo);
++					break;
++				}
++				default:
++					p += sprintf(p, "%x", ntohs(*(uint16_t *)co_data(co)));
++					break;
++				}
++				conf_option_set(lcp_peer, co->type, co->length, co_data(co));
++				conf_option_encode(&ack, co->type, co->length, co_data(co));
++				break;
++			case LCP_COPT_MAGIC:
++				p += sprintf(p, "%x", ntohl(*(uint32_t *)co_data(co)));
++				conf_option_set(lcp_peer, co->type, co->length, co_data(co));
++				conf_option_encode(&ack, co->type, co->length, co_data(co));
++				break;
++			case LCP_COPT_PFC:
++			case LCP_COPT_ACFC:
++				conf_option_set(lcp_peer, co->type, co->length, co_data(co));
++				conf_option_encode(&ack, co->type, co->length, co_data(co));
++				break;
++			default:
++				conf_option_encode(&reject, co->type, co->length, co_data(co));
++				break;
++			}
++			log_debug("%s\n", buff);
++			olen -= co->length;
++			co = (struct conf_option *)((uint8_t *)co + co->length);
++		}
++		if (header->code == LCP_CONF_REQUEST) {
++			int ret = -1;
++			ret = lcp_option_send(tunnel, header->id, LCP_CONF_ACK, &ack, 0);
++			if (ret < 0) {
++				log_error("send conf_ack failed %d: %s\n", errno, strerror(errno));
++				exit(1);
++			}
++			ret = lcp_option_send(tunnel, header->id, LCP_CONF_NAK, &nack, 0);
++			if (ret < 0) {
++				log_error("send conf_ack failed %d: %s\n", errno, strerror(errno));
++				exit(1);
++			}
++			ret = lcp_option_send(tunnel, header->id, LCP_CONF_REJECT, &reject, 0);
++			if (ret < 0) {
++				log_error("send conf_ack failed %d: %s\n", errno, strerror(errno));
++				exit(1);
++			}
++			switch (tunnel->tun_state) {
++			case TUN_PPP_LCP:
++				log_debug("\n\nmove to establishment phase\n");
++				tunnel->tun_state = TUN_PPP_IPCP;
++			default:
++				break;
++			}
++		}
++		conf_option_free(&ack);
++		conf_option_free(&nack);
++		conf_option_free(&reject);
++
++		break;
++	}
++	case LCP_CONF_ACK:
++	{
++		int olen = ntohs(header->length);
++		struct conf_option *co = NULL;
++		olen -= sizeof(struct lcp_header);
++		co = (struct conf_option *)(header + 1);
++		while (olen > 0) {
++			char buff[128];
++			char *p = buff;
++			conf_option_set(lcp_self, co->type, co->length, co_data(co));
++			p += sprintf(p, "option %s: ", lcp_valid_options[co->type].name);
++			switch (co->type) {
++			case LCP_COPT_MRU:
++				p += sprintf(p, "%d", ntohs(*(uint16_t *)co_data(co)));
++				break;
++			case LCP_COPT_ACCM:
++				p += sprintf(p, "%x", ntohl(*(uint32_t *)co_data(co)));
++				break;
++			case LCP_COPT_AUTH:
++				p += sprintf(p, "%x", ntohs(*(uint16_t *)co_data(co)));
++				break;
++			case LCP_COPT_MAGIC:
++				p += sprintf(p, "%x", ntohl(*(uint32_t *)co_data(co)));
++				break;
++			case LCP_COPT_PFC:
++			case LCP_COPT_ACFC:
++				break;
++			default:
++				break;
++			}
++			log_debug("%s\n", buff);
++			olen -= co->length;
++			co = (struct conf_option *)((uint8_t *)co + co->length);
++		}
++
++		if (tunnel->tun_state == TUN_PPP_LCP) {
++			log_debug("\n\nentering authenticate phase\n");
++			tunnel->tun_state = TUN_PPP_IPCP;
++		}
++		break;
++	}
++	case LCP_CONF_NAK:
++	{
++		int olen = ntohs(header->length);
++		struct conf_option *co = NULL;
++		olen -= sizeof(struct lcp_header);
++		co = (struct conf_option *)(header + 1);
++		while (olen > 0) {
++			char buff[128];
++			char *p = buff;
++			conf_option_set(lcp_self, co->type, 0, NULL);
++			p += sprintf(p, "option %s: ", lcp_valid_options[co->type].name);
++			switch (co->type) {
++			case LCP_COPT_MRU:
++				p += sprintf(p, "%d", ntohs(*(uint16_t *)co_data(co)));
++				break;
++			case LCP_COPT_ACCM:
++				p += sprintf(p, "%x", ntohl(*(uint32_t *)co_data(co)));
++				break;
++			case LCP_COPT_AUTH:
++				p += sprintf(p, "%x", ntohs(*(uint16_t *)co_data(co)));
++				break;
++			case LCP_COPT_MAGIC:
++				p += sprintf(p, "%x", ntohl(*(uint32_t *)co_data(co)));
++				break;
++			case LCP_COPT_PFC:
++			case LCP_COPT_ACFC:
++				break;
++			default:
++				break;
++			}
++			log_debug("%s\n", buff);
++			olen -= co->length;
++			co = (struct conf_option *)((uint8_t *)co + co->length);
++		}
++		break;
++	}
++	case LCP_CONF_REJECT:
++	{
++		int olen = ntohs(header->length);
++		struct conf_option *co = NULL;
++		olen -= sizeof(struct lcp_header);
++		co = (struct conf_option *)(header + 1);
++		while (olen > 0) {
++			char buff[128];
++			char *p = buff;
++			conf_option_set(lcp_self, co->type, 0, NULL);
++			p += sprintf(p, "option %s: ", lcp_valid_options[co->type].name);
++			switch (co->type) {
++			case LCP_COPT_MRU:
++				p += sprintf(p, "%d", ntohs(*(uint16_t *)co_data(co)));
++				break;
++			case LCP_COPT_ACCM:
++				p += sprintf(p, "%x", ntohl(*(uint32_t *)co_data(co)));
++				break;
++			case LCP_COPT_AUTH:
++				p += sprintf(p, "%x", ntohs(*(uint16_t *)co_data(co)));
++				break;
++			case LCP_COPT_MAGIC:
++				p += sprintf(p, "%x", ntohl(*(uint32_t *)co_data(co)));
++				break;
++			case LCP_COPT_PFC:
++			case LCP_COPT_ACFC:
++				break;
++			default:
++				break;
++			}
++			log_debug("%s\n", buff);
++			olen -= co->length;
++			co = (struct conf_option *)((uint8_t *)co + co->length);
++		}
++		break;
++	}
++	case LCP_TERM_REQUEST:
++		break;
++	case LCP_TERM_ACK:
++		break;
++	case LCP_CODE_REJECT:
++		break;
++	case LCP_PROT_REJECT:
++		break;
++	case LCP_ECHO_REQUEST:
++		break;
++	case LCP_ECHO_REPLY:
++		break;
++	case LCP_DISCARD:
++		break;
++	default:
++		/* ignore */
++		break;
++	}
++
++	return 0;
++}
++
++struct ipcp_header {
++	uint8_t   code;
++#define IPCP_CONF_REQUEST    1
++#define IPCP_CONF_ACK        2
++#define IPCP_CONF_NAK        3
++#define IPCP_CONF_REJECT     4
++#define IPCP_TERM_REQUEST    5
++#define IPCP_TERM_ACK        6
++#define IPCP_CODE_REJECT     7
++	uint8_t   id;
++	uint16_t length;
++};
++
++#define IPCP_COPT_ADDRESSES      1
++#define IPCP_COPT_COMPRESS       2
++#define IPCP_COPT_ADDRESS        3
++#define IPCP_COPT_PRIMARY_DNS    129
++#define IPCP_COPT_SECONDARY_DNS  131
++const char *ipcp_valid_options[256] = {
++	[0] = "",
++	[1] = "IPCP Option addresses",
++	[2] = "IPCP Option compress",
++	[3] = "IPCP Option address",
++	[129] = "IPCP Option primary dns",
++	[131] = "IPCP Option secondary dns",
++};
++
++const char *ipcp_code_name[] = {
++	"",
++	"IPCP Configure-Request",
++	"IPCP Configure-Ack",
++	"IPCP Configure-Nak",
++	"IPCP Configure-Reject",
++	"IPCP Terminate-Request",
++	"IPCP Terminate-Ack",
++	"IPCP Code-Reject",
++};
++
++int nroutes = 0;
++char **routes = NULL;
++
++uint32_t ip_address = 0;
++uint32_t peer_address = 0;
++uint32_t primary_dns = 0;
++uint32_t secondary_dns = 0;
++
++int ipcp_add_route(struct tunnel *tunnel, uint32_t dst, uint32_t mask, uint32_t gw)
++{
++	int ret = 0;
++	struct rtentry rt;
++	struct sockaddr_in *sin = NULL;
++
++	memset(&rt, 0, sizeof(rt));
++	rt.rt_dev = tunnel->tun_iface;
++	rt.rt_flags = RTF_GATEWAY;
++
++	sin = (struct sockaddr_in *)&rt.rt_dst;
++	sin->sin_family = AF_INET;
++	sin->sin_port = 0;
++	sin->sin_addr.s_addr = dst & htonl(mask);
++
++	sin = (struct sockaddr_in *)&rt.rt_gateway;
++	sin->sin_family = AF_INET;
++	sin->sin_port = 0;
++	sin->sin_addr.s_addr = gw;
++
++	sin = (struct sockaddr_in *)&rt.rt_genmask;
++	sin->sin_family = AF_INET;
++	sin->sin_port = 0;
++	sin->sin_addr.s_addr = htonl(mask);
++
++	int sd = socket(AF_INET, SOCK_DGRAM, 0);
++	ret = ioctl(sd, SIOCADDRT, &rt);
++	if (ret == 0) {
++		log_debug("route add success\n");
++	} else {
++		log_error("route add failed %d: %s\n", errno, strerror(errno));
++	}
++	close(sd);
++
++	return ret;
++}
++int ipcp_option_send(struct tunnel *tunnel, int id, int code, struct conf_option_list *optlist, int force)
++{
++	int ret = -1;
++	if (optlist && optlist->head) {
++		uint8_t *packet = (uint8_t *)optlist->head;
++		struct ipcp_header *header = ((struct ipcp_header *)packet) - 1;
++		unsigned short *ppp_type = ((unsigned short *)header) - 1;
++		int len = conf_option_length(optlist);
++		int hdrlen = sizeof(struct ipcp_header) + sizeof(uint16_t);
++
++		if (len > 0 || force) {
++			ssize_t pktsize;
++			struct ppp_packet *packet = NULL;
++
++			*ppp_type = htons(PPP_IPCP);
++			header->code = code;
++			header->id = id ? id : lcp_id ++;
++			header->length = htons(len + sizeof(*header));
++			log_debug("send ipcp %d\n", len);
++
++			pktsize = hdrlen + len;
++			packet = malloc(sizeof(*packet) + 6 + pktsize);
++			if (packet == NULL) {
++				goto out;
++			}
++			packet->len = pktsize;
++			memcpy(pkt_data(packet), ppp_type, pktsize);
++
++			log_debug("%s ---> gateway (%lu bytes)\n", PPP_DAEMON,
++				  packet->len);
++#if HAVE_USR_SBIN_PPPD
++			log_packet("pppd:   ", packet->len, pkt_data(packet));
++#else
++			log_packet("ppp:   ", packet->len, pkt_data(packet));
++#endif
++			pool_push(&tunnel->pty_to_ssl_pool, packet);
++		}
++		ret = 0;
++	}
++
++out:
++	return ret;
++}
++int ipcp_packet(struct tunnel *tunnel, void *packet, int len)
++{
++	int ret = 0;
++	struct ipcp_header *header = packet;
++
++	log_debug("packet %s\n", ipcp_code_name[header->code]);
++	switch (header->code) {
++	case IPCP_CONF_REQUEST:
++	{
++		int olen = ntohs(header->length);
++		struct conf_option *co = NULL;
++		struct conf_option_list ack;
++		struct conf_option_list nack;
++		struct conf_option_list reject;
++		struct conf_option_list request;
++		conf_option_init(&ack);
++		conf_option_init(&nack);
++		conf_option_init(&reject);
++		conf_option_init(&request);
++		olen -= sizeof(struct ipcp_header);
++		co = (struct conf_option *)(header + 1);
++		while (olen > 0) {
++			char buff[128];
++			char *p = buff;
++			p += sprintf(p, "option %s: ", ipcp_valid_options[co->type]);
++			switch (co->type) {
++			case IPCP_COPT_ADDRESSES:
++				p += sprintf(p, "%x", ntohl(*(uint32_t *)co_data(co)));
++				conf_option_encode(&ack, co->type, co->length, co_data(co));
++				break;
++			case IPCP_COPT_COMPRESS:
++				conf_option_encode(&ack, co->type, co->length, co_data(co));
++				break;
++			case IPCP_COPT_ADDRESS:
++				p += sprintf(p, "%x", ntohl(*(uint32_t *)co_data(co)));
++				conf_option_encode(&ack, co->type, co->length, co_data(co));
++				peer_address = *(uint32_t *)co_data(co);
++				break;
++			default:
++				break;
++			}
++			log_debug("%s\n", buff);
++			olen -= co->length;
++			co = (struct conf_option *)((uint8_t *)co + co->length);
++		}
++		if (header->code == IPCP_CONF_REQUEST) {
++			int ret = -1;
++			ret = ipcp_option_send(tunnel, header->id, IPCP_CONF_ACK, &ack, 0);
++			if (ret < 0) {
++				log_debug("send conf_ack failed %d: %s\n", errno, strerror(errno));
++				exit(1);
++			}
++			ret = ipcp_option_send(tunnel, header->id, IPCP_CONF_NAK, &nack, 0);
++			if (ret < 0) {
++				log_debug("send conf_ack failed %d: %s\n", errno, strerror(errno));
++				exit(1);
++			}
++			ret = ipcp_option_send(tunnel, header->id, IPCP_CONF_REJECT, &reject, 0);
++			if (ret < 0) {
++				log_debug("send conf_ack failed %d: %s\n", errno, strerror(errno));
++				exit(1);
++			}
++
++			do {
++				uint32_t compress = htonl(0x002d0f01);
++				conf_option_encode(&request, IPCP_COPT_ADDRESS, 6, &ip_address);
++				conf_option_encode(&request, IPCP_COPT_COMPRESS, 6, &compress);
++				// conf_option_encode(&request, IPCP_COPT_PRIMARY_DNS, 6, &primary_dns);
++				// conf_option_encode(&request, IPCP_COPT_SECONDARY_DNS, 6, &secondary_dns);
++				ret = ipcp_option_send(tunnel, 0, IPCP_CONF_REQUEST, &request, 0);
++				if (ret < 0) {
++					log_debug("send conf_ack failed %d: %s\n", errno, strerror(errno));
++					exit(1);
++				}
++			} while (0);
++		}
++		conf_option_free(&ack);
++		conf_option_free(&nack);
++		conf_option_free(&reject);
++		conf_option_free(&request);
++
++		break;
++	}
++	case IPCP_CONF_ACK:
++	{
++		int olen = ntohs(header->length);
++		struct conf_option *co = NULL;
++		olen -= sizeof(struct lcp_header);
++		co = (struct conf_option *)(header + 1);
++		while (olen > 0) {
++			char buff[128];
++			char *p = buff;
++			p += sprintf(p, "option %s: ", ipcp_valid_options[co->type]);
++			switch (co->type) {
++			case IPCP_COPT_ADDRESSES:
++				p += sprintf(p, "%x", ntohl(*(uint32_t *)co_data(co)));
++				break;
++			case IPCP_COPT_COMPRESS:
++				break;
++			case IPCP_COPT_ADDRESS:
++				p += sprintf(p, "%x", ntohl(*(uint32_t *)co_data(co)));
++				ip_address = *(uint32_t *)co_data(co);
++				break;
++			case IPCP_COPT_PRIMARY_DNS:
++				p += sprintf(p, "%x", ntohl(*(uint32_t *)co_data(co)));
++				primary_dns = *(uint32_t *)co_data(co);
++				break;
++			case IPCP_COPT_SECONDARY_DNS:
++				p += sprintf(p, "%x", ntohl(*(uint32_t *)co_data(co)));
++				secondary_dns = *(uint32_t *)co_data(co);
++				break;
++			default:
++				break;
++			}
++			log_debug("%s\n", buff);
++			olen -= co->length;
++			co = (struct conf_option *)((uint8_t *)co + co->length);
++		}
++
++		int tun_ifup(char *ifname, uint32_t ip_addr, uint32_t peer_addr);
++		tun_ifup(tunnel->tun_iface, ip_address, peer_address);
++		ipv4_set_tunnel_routes(tunnel);
++		break;
++	}
++	case IPCP_CONF_NAK:
++	{
++		int send_request = 0;
++		int olen = ntohs(header->length);
++		struct conf_option *co = NULL;
++		olen -= sizeof(struct lcp_header);
++		co = (struct conf_option *)(header + 1);
++		while (olen > 0) {
++			char buff[128];
++			char *p = buff;
++			p += sprintf(p, "option %s: ", ipcp_valid_options[co->type]);
++			switch (co->type) {
++			case IPCP_COPT_ADDRESSES:
++				p += sprintf(p, "%x", ntohl(*(uint32_t *)co_data(co)));
++				break;
++			case IPCP_COPT_COMPRESS:
++				break;
++			case IPCP_COPT_ADDRESS:
++				p += sprintf(p, "%x", ntohl(*(uint32_t *)co_data(co)));
++				if (ip_address != *(uint32_t *)co_data(co)) {
++					ip_address = *(uint32_t *)co_data(co);
++					send_request = 1;
++				}
++				break;
++			case IPCP_COPT_PRIMARY_DNS:
++				p += sprintf(p, "%x", ntohl(*(uint32_t *)co_data(co)));
++				if (primary_dns != *(uint32_t *)co_data(co)) {
++					primary_dns = *(uint32_t *)co_data(co);
++					send_request = 1;
++				}
++				break;
++			case IPCP_COPT_SECONDARY_DNS:
++				p += sprintf(p, "%x", ntohl(*(uint32_t *)co_data(co)));
++				if (secondary_dns != *(uint32_t *)co_data(co)) {
++					secondary_dns = *(uint32_t *)co_data(co);
++					send_request = 1;
++				}
++				break;
++			default:
++				break;
++			}
++			log_debug("%s\n", buff);
++			olen -= co->length;
++			co = (struct conf_option *)((uint8_t *)co + co->length);
++		}
++
++		if (send_request) {
++			struct conf_option_list request;
++			conf_option_init(&request);
++			conf_option_encode(&request, IPCP_COPT_ADDRESS, 6, &ip_address);
++			// conf_option_encode(&request, IPCP_COPT_PRIMARY_DNS, 6, &primary_dns);
++			// conf_option_encode(&request, IPCP_COPT_SECONDARY_DNS, 6, &secondary_dns);
++			ret = ipcp_option_send(tunnel, 0, IPCP_CONF_REQUEST, &request, 0);
++			if (ret < 0) {
++				log_debug("send conf_ack failed %d: %s\n", errno, strerror(errno));
++				exit(1);
++			}
++			conf_option_free(&request);
++		}
++		break;
++	}
++	case IPCP_CONF_REJECT:
++	{
++		int olen = ntohs(header->length);
++		struct conf_option *co = NULL;
++		olen -= sizeof(struct lcp_header);
++		co = (struct conf_option *)(header + 1);
++		while (olen > 0) {
++			char buff[128];
++			char *p = buff;
++			p += sprintf(p, "option %s: ", ipcp_valid_options[co->type]);
++			switch (co->type) {
++			case IPCP_COPT_ADDRESSES:
++				p += sprintf(p, "%x", ntohl(*(uint32_t *)co_data(co)));
++				break;
++			case IPCP_COPT_COMPRESS:
++				break;
++			case IPCP_COPT_ADDRESS:
++				p += sprintf(p, "%x", ntohl(*(uint32_t *)co_data(co)));
++				break;
++			case IPCP_COPT_PRIMARY_DNS:
++				p += sprintf(p, "%x", ntohl(*(uint32_t *)co_data(co)));
++				break;
++			case IPCP_COPT_SECONDARY_DNS:
++				p += sprintf(p, "%x", ntohl(*(uint32_t *)co_data(co)));
++				break;
++			default:
++				break;
++			}
++			log_debug("%s\n", buff);
++			olen -= co->length;
++			co = (struct conf_option *)((uint8_t *)co + co->length);
++		}
++
++		do {
++			struct conf_option_list request;
++			conf_option_init(&request);
++			conf_option_encode(&request, IPCP_COPT_ADDRESS, 6, &ip_address);
++			// conf_option_encode(&request, IPCP_COPT_PRIMARY_DNS, 6, &primary_dns);
++			// conf_option_encode(&request, IPCP_COPT_SECONDARY_DNS, 6, &secondary_dns);
++			ret = ipcp_option_send(tunnel, 0, IPCP_CONF_REQUEST, &request, 0);
++			if (ret < 0) {
++				log_debug("send conf_ack failed %d: %s\n", errno, strerror(errno));
++				exit(1);
++			}
++		} while (0);
++		break;
++	}
++	case IPCP_TERM_REQUEST:
++		break;
++	case IPCP_TERM_ACK:
++		break;
++	case IPCP_CODE_REJECT:
++		break;
++	default:
++		/* ignore */
++		break;
++	}
++
++	return 0;
++}
++
++
+ /*
+  * Thread to read bytes from the pppd pty, convert them to ppp packets and add
+  * them to the 'pty_to_ssl' pool.
+@@ -192,6 +1032,17 @@ static void *pppd_read(void *arg)
+ 
+ 	log_debug("%s thread\n", __func__);
+ 
++	if (tunnel->use_tun) {
++		switch (tunnel->tun_state) {
++		case TUN_PPP_LCP:
++			conf_request(tunnel);
++			break;
++		case TUN_PPP_IPCP:
++		case TUN_PPP_SESSION:
++			break;
++		}
++	}
++
+ 	// Wait for pppd to be ready
+ 	off_w = 0;
+ 	while (1) {
+@@ -218,6 +1069,31 @@ static void *pppd_read(void *arg)
+ 			SEM_POST(&sem_pppd_ready);
+ 			first_time = 0;
+ 		}
++		if (tunnel->use_tun) {
++			ssize_t pktsize;
++			struct ppp_packet *packet = NULL;
++
++			pktsize = n + 2;
++			packet = malloc(sizeof(*packet) + 6 + pktsize);
++			if (packet == NULL) {
++				goto exit;
++			}
++			packet->len = pktsize;
++			pkt_data(packet)[0] = 0x00;
++			pkt_data(packet)[1] = 0x21;
++			memcpy(pkt_data(packet) + 2, buf, n);
++
++			log_debug("%s ---> gateway (%lu bytes)\n", PPP_DAEMON,
++				  packet->len);
++#if HAVE_USR_SBIN_PPPD
++			log_packet("pppd:   ", packet->len, pkt_data(packet));
++#else
++			log_packet("ppp:   ", packet->len, pkt_data(packet));
++#endif
++			pool_push(&tunnel->pty_to_ssl_pool, packet);
++			continue;
++		}
++
+ 		off_w += n;
+ 
+ 		// We have data in the buffer, there may be zero, one or many
+@@ -308,17 +1184,44 @@ static void *pppd_write(void *arg)
+ 		// This waits until a packet has arrived from the gateway
+ 		packet = pool_pop(&tunnel->ssl_to_pty_pool);
+ 
+-		hdlc_bufsize = estimated_encoded_size(packet->len);
+-		hdlc_buffer = malloc(hdlc_bufsize);
+-		if (hdlc_buffer == NULL) {
+-			log_error("malloc: %s\n", strerror(errno));
+-			break;
+-		}
+-		len = hdlc_encode(hdlc_buffer, hdlc_bufsize,
+-		                  pkt_data(packet), packet->len);
+-		if (len < 0) {
+-			log_error("Failed to encode PPP packet into HDLC frame.\n");
+-			goto err_free_buf;
++		if (tunnel->use_tun) {
++			void *pkt_type = pkt_data(packet);
++
++			hdlc_bufsize = len = packet->len;
++			switch (ntohs(*(uint16_t *)pkt_type)) {
++			case PPP_LCP:
++				lcp_packet(tunnel, pkt_data(packet) + 2, len - 2);
++				continue;
++			case PPP_IPCP:
++				ipcp_packet(tunnel, pkt_data(packet) + 2, len - 2);
++				continue;
++			case PPP_IP:
++			case PPP_IPV6:
++				break;
++			default:
++				goto out_free_packet;
++			}
++
++			hdlc_buffer = malloc(packet->len);
++			if (hdlc_buffer == NULL) {
++				log_error("malloc: %s\n", strerror(errno));
++				break;
++			}
++
++			memcpy(hdlc_buffer, pkt_data(packet) + 2, packet->len - 2);
++		} else {
++			hdlc_bufsize = estimated_encoded_size(packet->len);
++			hdlc_buffer = malloc(hdlc_bufsize);
++			if (hdlc_buffer == NULL) {
++				log_error("malloc: %s\n", strerror(errno));
++				break;
++			}
++			len = hdlc_encode(hdlc_buffer, hdlc_bufsize,
++					  pkt_data(packet), packet->len);
++			if (len < 0) {
++				log_error("Failed to encode PPP packet into HDLC frame.\n");
++				goto err_free_buf;
++			}
+ 		}
+ 
+ 		written = 0;
+@@ -349,6 +1252,7 @@ static void *pppd_write(void *arg)
+ 		}
+ 
+ 		free(hdlc_buffer);
++out_free_packet:
+ 		free(packet);
+ 		continue;
+ err_free_buf:
+@@ -497,6 +1401,11 @@ static void *ssl_read(void *arg)
+ 				char line[ARRAY_SIZE("[xxx.xxx.xxx.xxx], ns [xxx.xxx.xxx.xxx, xxx.xxx.xxx.xxx], ns_suffix []") + MAX_DOMAIN_LENGTH];
+ 
+ 				set_tunnel_ips(tunnel, packet);
++
++				if (tunnel->use_tun) {
++					int tun_ifup(char *ifname, uint32_t ip_addr, uint32_t peer_addr);
++					tun_ifup(tunnel->tun_iface, tunnel->ipv4.ip_addr.s_addr, 0);
++				}
+ 				strcpy(line, "[");
+ 				strncat(line, inet_ntoa(tunnel->ipv4.ip_addr), 15);
+ 				strcat(line, "], ns [");
+diff --git a/src/ipv4.h b/src/ipv4.h
+index fc1406b..7fd492e 100644
+--- a/src/ipv4.h
++++ b/src/ipv4.h
+@@ -57,6 +57,7 @@ struct rtentry {
+ 
+ struct ipv4_config {
+ 	struct in_addr	ip_addr;
++	struct in_addr	peer_addr;
+ 
+ 	struct in_addr	ns1_addr;
+ 	struct in_addr	ns2_addr;
+diff --git a/src/tunnel.c b/src/tunnel.c
+index 32a5e39..a0e7bd7 100644
+--- a/src/tunnel.c
++++ b/src/tunnel.c
+@@ -64,6 +64,7 @@
+ #include <errno.h>
+ #include <signal.h>
+ #include <string.h>
++#include <linux/if_tun.h>
+ 
+ 
+ struct ofv_varr {
+@@ -154,7 +155,127 @@ static int on_ppp_if_down(struct tunnel *tunnel)
+ 	return 0;
+ }
+ 
+-static int pppd_run(struct tunnel *tunnel)
++#define TUN_PATH "/dev/net/tun"
++
++#define TUN_ASSERT(cond, fmt, ...) do {                      \
++		if (! (cond)) {                              \
++			log_info(fmt "\n", ##__VA_ARGS__);   \
++			exit(1);                             \
++		}                                            \
++	} while (0)
++
++static int
++tun_open(struct ifreq *ifr)
++{
++	int ret = 0;
++	int fd = -1;
++
++	fd = open(TUN_PATH, O_RDWR, 0);
++	if (fd >= 0) {
++		ret = ioctl(fd, TUNSETIFF, (unsigned long)ifr);
++		if (ret < 0) {
++			log_error("ioctl: %s\n", strerror(errno));
++			close(fd);
++			return ret;
++		}
++		log_info("interface <%s> created\n", ifr->ifr_name);
++	} else {
++		log_error("fcntl: %s\n", strerror(errno));
++	}
++
++	return fd;
++}
++
++static int
++__attribute__((unused))
++tun_close(int fd)
++{
++	return close(fd);
++}
++
++int
++tun_ifup(char *ifname, uint32_t ip_addr, uint32_t peer_addr)
++{
++	struct ifreq ifreq = {
++		.ifr_flags = IFF_UP,
++	};
++	struct sockaddr_in *sin = NULL;
++	int fd = -1;
++	int ret = -1;
++
++	fd = socket(AF_INET, SOCK_DGRAM, 0);
++	if (fd < 0) {
++		return fd;
++	}
++	strncpy(ifreq.ifr_name, ifname, IFNAMSIZ);
++	ret = ioctl(fd, SIOCGIFFLAGS, (unsigned long)&ifreq);
++	TUN_ASSERT(ret == 0, "ioctl get ifflags", 0);
++	if (ret == 0) {
++		ifreq.ifr_flags |= IFF_UP;
++		ret = ioctl(fd, SIOCSIFFLAGS, (unsigned long)&ifreq);
++		TUN_ASSERT(ret == 0, "ioctl set ifflags", 0);
++	}
++
++	if (ip_addr != 0) {
++		sin = (struct sockaddr_in *)&ifreq.ifr_addr;
++		sin->sin_family = AF_INET;
++		sin->sin_port = 0;
++		sin->sin_addr.s_addr = ip_addr;
++		ret = ioctl(fd, SIOCSIFADDR, (unsigned long)&ifreq);
++		TUN_ASSERT(ret == 0, "ioctl set ifaddr err: %s", strerror(errno));
++		log_info("setup <%s> ip addr to %s\n", ifname, inet_ntoa(sin->sin_addr));
++	}
++
++	if (peer_addr != 0) {
++		sin = (struct sockaddr_in *)&ifreq.ifr_addr;
++		sin->sin_family = AF_INET;
++		sin->sin_port = 0;
++		sin->sin_addr.s_addr = peer_addr;
++		ret = ioctl(fd, SIOCSIFDSTADDR, (unsigned long)&ifreq);
++		TUN_ASSERT(ret == 0, "ioctl set dst ifaddr", 0);
++	}
++
++	close(fd);
++
++	return ret;
++}
++
++static int
++__attribute__((unused))
++tun_setup(struct tunnel *tunnel)
++{
++	int flags = 0;
++	int tun_fd = -1;
++        struct ifreq ifreq = {
++                .ifr_flags = IFF_TUN | IFF_NO_PI,
++        };
++
++        tun_fd = tun_open(&ifreq);
++	if (tun_fd < 0) {
++		log_error("tun_open failed: %s\n", strerror(errno));
++		return 1;
++	}
++
++	flags = fcntl(tun_fd, F_GETFL, 0);
++	if (flags == -1)
++		flags = 0;
++	if (fcntl(tun_fd, F_SETFL, flags | O_NONBLOCK) == -1) {
++		log_error("fcntl failed: %s\n", strerror(errno));
++		return 1;
++	}
++
++	strcpy(tunnel->tun_iface, ifreq.ifr_name);
++	tun_ifup(tunnel->tun_iface, 0, 0);
++
++	tunnel->pppd_pid = -1;
++	tunnel->pppd_pty = tun_fd;
++
++	return 0;
++}
++
++static int
++__attribute__((unused))
++pppd_run(struct tunnel *tunnel)
+ {
+ 	pid_t pid;
+ 	int amaster;
+@@ -232,7 +353,7 @@ static int pppd_run(struct tunnel *tunnel)
+ 			static const char *const v[] = {
+ 				ppp_path,
+ 				"115200", // speed
+-				":192.0.2.1", // <local_IP_address>:<remote_IP_address>
++				":10.168.1.71", // <local_IP_address>:<remote_IP_address>
+ 				"noipdefault",
+ 				"noaccomp",
+ 				"noauth",
+@@ -464,6 +585,7 @@ int ppp_interface_is_up(struct tunnel *tunnel)
+ 		             && strstr(ifa->ifa_name, tunnel->config->pppd_ifname)
+ 		             != NULL)
+ 		            || strstr(ifa->ifa_name, "ppp") != NULL
++		            || strstr(ifa->ifa_name, "tun") != NULL
+ #endif
+ #if HAVE_USR_SBIN_PPP
+ 		            strstr(ifa->ifa_name, "tun") != NULL
+@@ -1128,7 +1250,8 @@ int run_tunnel(struct vpn_config *config)
+ 		goto err_tunnel;
+ 
+ 	// Step 3: get configuration
+-	log_debug("Retrieving configuration\n");
++	tunnel.use_tun = 1;
++	log_info("Retrieving configuration\n");
+ 	ret = auth_get_config(&tunnel);
+ 	if (ret != 1) {
+ 		log_error("Could not get VPN configuration (%s).\n",
+@@ -1138,13 +1261,17 @@ int run_tunnel(struct vpn_config *config)
+ 	}
+ 
+ 	// Step 4: run a pppd process
+-	log_debug("Establishing the tunnel\n");
+-	ret = pppd_run(&tunnel);
++	log_info("Establishing the tunnel\n");
++	if (tunnel.use_tun) {
++		ret = tun_setup(&tunnel);
++	} else {
++		ret = pppd_run(&tunnel);
++	}
+ 	if (ret)
+ 		goto err_tunnel;
+ 
+ 	// Step 5: ask gateway to start tunneling
+-	log_debug("Switch to tunneling mode\n");
++	log_info("Switch to tunneling mode\n");
+ 	ret = http_send(&tunnel,
+ 	                "GET /remote/sslvpn-tunnel HTTP/1.1\r\n"
+ 	                "Host: sslvpn\r\n"
+@@ -1160,7 +1287,7 @@ int run_tunnel(struct vpn_config *config)
+ 	ret = 0;
+ 
+ 	// Step 6: perform io between pppd and the gateway, while tunnel is up
+-	log_debug("Starting IO through the tunnel\n");
++	log_info("Starting IO through the tunnel\n");
+ 	io_loop(&tunnel);
+ 
+ 	log_debug("disconnecting\n");
+diff --git a/src/tunnel.h b/src/tunnel.h
+index 31eb045..af4d64e 100644
+--- a/src/tunnel.h
++++ b/src/tunnel.h
+@@ -54,10 +54,17 @@ enum tunnel_state {
+ 	STATE_DISCONNECTING
+ };
+ 
++enum tun_ppp_state {
++	TUN_PPP_LCP,
++	TUN_PPP_IPCP,
++	TUN_PPP_SESSION,
++};
++
+ struct tunnel {
+ 	struct vpn_config *config;
+ 
+ 	enum tunnel_state state;
++	enum tun_ppp_state tun_state;
+ 	char cookie[COOKIE_SIZE + 1];
+ 
+ 	struct ppp_packet_pool ssl_to_pty_pool;
+@@ -65,6 +72,8 @@ struct tunnel {
+ 
+ 	pid_t	pppd_pid;
+ 	pid_t	pppd_pty;
++	int	use_tun;
++	char	tun_iface[ROUTE_IFACE_LEN];
+ 	char	ppp_iface[ROUTE_IFACE_LEN];
+ 
+ 	int	ssl_socket;