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ppp.c
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ppp.c
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/*
* OpenConnect (SSL + DTLS) VPN client
*
* Copyright © 2020-2021 David Woodhouse, Daniel Lenski
*
* Authors: David Woodhouse <[email protected]>, Daniel Lenski <[email protected]>
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public License
* version 2.1, as published by the Free Software Foundation.
*
* This program 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
* Lesser General Public License for more details.
*/
#include <config.h>
#include "openconnect-internal.h"
#include "ppp.h"
#include <errno.h>
static const uint16_t fcstab[256] = {
0x0000, 0x1189, 0x2312, 0x329b, 0x4624, 0x57ad, 0x6536, 0x74bf,
0x8c48, 0x9dc1, 0xaf5a, 0xbed3, 0xca6c, 0xdbe5, 0xe97e, 0xf8f7,
0x1081, 0x0108, 0x3393, 0x221a, 0x56a5, 0x472c, 0x75b7, 0x643e,
0x9cc9, 0x8d40, 0xbfdb, 0xae52, 0xdaed, 0xcb64, 0xf9ff, 0xe876,
0x2102, 0x308b, 0x0210, 0x1399, 0x6726, 0x76af, 0x4434, 0x55bd,
0xad4a, 0xbcc3, 0x8e58, 0x9fd1, 0xeb6e, 0xfae7, 0xc87c, 0xd9f5,
0x3183, 0x200a, 0x1291, 0x0318, 0x77a7, 0x662e, 0x54b5, 0x453c,
0xbdcb, 0xac42, 0x9ed9, 0x8f50, 0xfbef, 0xea66, 0xd8fd, 0xc974,
0x4204, 0x538d, 0x6116, 0x709f, 0x0420, 0x15a9, 0x2732, 0x36bb,
0xce4c, 0xdfc5, 0xed5e, 0xfcd7, 0x8868, 0x99e1, 0xab7a, 0xbaf3,
0x5285, 0x430c, 0x7197, 0x601e, 0x14a1, 0x0528, 0x37b3, 0x263a,
0xdecd, 0xcf44, 0xfddf, 0xec56, 0x98e9, 0x8960, 0xbbfb, 0xaa72,
0x6306, 0x728f, 0x4014, 0x519d, 0x2522, 0x34ab, 0x0630, 0x17b9,
0xef4e, 0xfec7, 0xcc5c, 0xddd5, 0xa96a, 0xb8e3, 0x8a78, 0x9bf1,
0x7387, 0x620e, 0x5095, 0x411c, 0x35a3, 0x242a, 0x16b1, 0x0738,
0xffcf, 0xee46, 0xdcdd, 0xcd54, 0xb9eb, 0xa862, 0x9af9, 0x8b70,
0x8408, 0x9581, 0xa71a, 0xb693, 0xc22c, 0xd3a5, 0xe13e, 0xf0b7,
0x0840, 0x19c9, 0x2b52, 0x3adb, 0x4e64, 0x5fed, 0x6d76, 0x7cff,
0x9489, 0x8500, 0xb79b, 0xa612, 0xd2ad, 0xc324, 0xf1bf, 0xe036,
0x18c1, 0x0948, 0x3bd3, 0x2a5a, 0x5ee5, 0x4f6c, 0x7df7, 0x6c7e,
0xa50a, 0xb483, 0x8618, 0x9791, 0xe32e, 0xf2a7, 0xc03c, 0xd1b5,
0x2942, 0x38cb, 0x0a50, 0x1bd9, 0x6f66, 0x7eef, 0x4c74, 0x5dfd,
0xb58b, 0xa402, 0x9699, 0x8710, 0xf3af, 0xe226, 0xd0bd, 0xc134,
0x39c3, 0x284a, 0x1ad1, 0x0b58, 0x7fe7, 0x6e6e, 0x5cf5, 0x4d7c,
0xc60c, 0xd785, 0xe51e, 0xf497, 0x8028, 0x91a1, 0xa33a, 0xb2b3,
0x4a44, 0x5bcd, 0x6956, 0x78df, 0x0c60, 0x1de9, 0x2f72, 0x3efb,
0xd68d, 0xc704, 0xf59f, 0xe416, 0x90a9, 0x8120, 0xb3bb, 0xa232,
0x5ac5, 0x4b4c, 0x79d7, 0x685e, 0x1ce1, 0x0d68, 0x3ff3, 0x2e7a,
0xe70e, 0xf687, 0xc41c, 0xd595, 0xa12a, 0xb0a3, 0x8238, 0x93b1,
0x6b46, 0x7acf, 0x4854, 0x59dd, 0x2d62, 0x3ceb, 0x0e70, 0x1ff9,
0xf78f, 0xe606, 0xd49d, 0xc514, 0xb1ab, 0xa022, 0x92b9, 0x8330,
0x7bc7, 0x6a4e, 0x58d5, 0x495c, 0x3de3, 0x2c6a, 0x1ef1, 0x0f78
};
#define foldfcs(fcs, c) ( ( (fcs) >> 8 ) ^ fcstab[(fcs ^ (c)) & 0xff] )
#define NEED_ESCAPE(c, map) ( (((c) < 0x20) && (map && (1UL << (c)))) || ((c) == 0x7d) || ((c) == 0x7e) )
#define HDLC_OUT(outp, c, map) do { \
if (NEED_ESCAPE((c), map)) { \
*outp++ = 0x7d; \
*outp++ = (c) ^ 0x20; \
} else \
*outp++ = (c); \
} while (0)
static struct pkt *hdlc_into_new_pkt(struct openconnect_info *vpninfo, struct pkt *old, int asyncmap)
{
int len = old->len + old->ppp.hlen;
const unsigned char *inp = old->data - old->ppp.hlen, *endp = inp + len;
unsigned char *outp;
uint16_t fcs = PPPINITFCS16;
/* Every byte in payload and 2-byte FCS potentially expands to two bytes,
* plus 2 for flag (0x7e) at start and end. We know that we will output
* at least 4 bytes so we can stash those in the header. */
struct pkt *p = alloc_pkt(vpninfo, len*2 + 2);
if (!p)
return NULL;
outp = p->data - 4;
*outp++ = 0x7e;
for (; inp < endp; inp++) {
fcs = foldfcs(fcs, *inp);
HDLC_OUT(outp, *inp, asyncmap);
}
/* Append FCS, escaped, little-endian */
fcs ^= 0xffff;
HDLC_OUT(outp, fcs & 0xff, asyncmap);
HDLC_OUT(outp, fcs >> 8, asyncmap);
*outp++ = 0x7e;
p->ppp.hlen = 4;
p->len = outp - p->data;
return p;
}
static int unhdlc_in_place(struct openconnect_info *vpninfo, unsigned char *bytes, int len, unsigned char **next)
{
unsigned char *inp = bytes, *endp = bytes + len;
unsigned char *outp = bytes;
int escape = 0;
uint16_t fcs = PPPINITFCS16;
if (*inp == 0x7e)
inp++;
else
vpn_progress(vpninfo, PRG_TRACE,
_("HDLC initial flag sequence (0x7e) is missing\n"));
while (inp < endp) {
unsigned char c = *inp++;
if (c == 0x7e)
goto done;
else if (escape) {
c ^= 0x20;
escape = 0;
} else if (c == 0x7d) {
escape = 1;
continue;
}
fcs = foldfcs(fcs, c);
*outp++ = c;
}
vpn_progress(vpninfo, PRG_ERR,
_("HDLC buffer ended without FCS and flag sequence (0x7e)\n"));
return -EINVAL;
done:
if (outp < bytes + 2) {
vpn_progress(vpninfo, PRG_ERR,
_("HDLC frame too short (%d bytes)\n"),
(int)(outp - bytes));
return -EINVAL;
}
outp -= 2; /* FCS */
if (next)
*next = inp; /* Pointing at the byte AFTER final 0x7e */
if (fcs != PPPGOODFCS16) {
vpn_progress(vpninfo, PRG_INFO,
_("Bad HDLC packet FCS %04x\n"), fcs);
dump_buf_hex(vpninfo, PRG_INFO, '<', bytes, len);
return -EINVAL;
} else {
vpn_progress(vpninfo, PRG_TRACE,
_("Un-HDLC'ed packet (%ld bytes -> %ld), FCS=0x%04x\n"),
(long)(inp - bytes), (long)(outp - bytes), fcs);
return outp - bytes;
}
}
static const char * const ppps_names[] = {
"DEAD",
"ESTABLISH",
"OPENED",
"AUTHENTICATE",
"NETWORK",
"TERMINATE"
};
static const char * const encap_names[PPP_ENCAP_MAX+1] = {
NULL,
"RFC1661",
"RFC1662 HDLC",
"F5",
"F5 HDLC",
"FORTINET",
};
static const char * const lcp_names[] = {
NULL,
"Configure-Request",
"Configure-Ack",
"Configure-Nak",
"Configure-Reject",
"Terminate-Request",
"Terminate-Ack",
"Code-Reject",
"Protocol-Reject",
"Echo-Request",
"Echo-Reply",
"Discard-Request",
};
static inline const char *proto_names(uint16_t proto)
{
static char unknown[21];
switch (proto) {
case PPP_LCP: return "LCP";
case PPP_IPCP: return "IPCP";
case PPP_IP6CP: return "IP6CP";
case PPP_CCP: return "CCP";
case PPP_IP: return "IPv4";
case PPP_IP6: return "IPv6";
default:
snprintf(unknown, 21, "unknown proto 0x%04x", proto);
return unknown;
}
}
int openconnect_ppp_new(struct openconnect_info *vpninfo,
int encap, int want_ipv4, int want_ipv6)
{
free(vpninfo->ppp);
struct oc_ppp *ppp = vpninfo->ppp = calloc(1, sizeof(*ppp));
if (!ppp)
return -ENOMEM;
/* Delay tunnel setup during PPP negotiation */
vpninfo->delay_tunnel_reason = "PPP negotiation";
/* Outgoing IPv4 address and IPv6 interface identifier bits,
* if already configured via another mechanism */
if (vpninfo->ip_info.addr)
ppp->out_ipv4_addr.s_addr = inet_addr(vpninfo->ip_info.addr);
if (vpninfo->ip_info.netmask6) {
char *slash = strchr(vpninfo->ip_info.netmask6, '/');
if (slash) *slash=0;
inet_pton(AF_INET6, vpninfo->ip_info.netmask6, &ppp->out_ipv6_addr);
if (slash) *slash='/';
} else if (vpninfo->ip_info.addr6) {
inet_pton(AF_INET6, vpninfo->ip_info.addr6, &ppp->out_ipv6_addr);
}
/* Nameservers to request from peer
* (see https://tools.ietf.org/html/rfc1877#section-1) */
if (!vpninfo->ip_info.dns[0] && !vpninfo->ip_info.nbns[0])
ppp->solicit_peerns = IPCP_DNS0|IPCP_DNS1|IPCP_NBNS0|IPCP_NBNS1;
ppp->encap = encap;
ppp->want_ipv4 = want_ipv4;
ppp->want_ipv6 = want_ipv6 && !vpninfo->disable_ipv6;
return ppp_reset(vpninfo);
}
int ppp_reset(struct openconnect_info *vpninfo)
{
struct oc_ppp *ppp = vpninfo->ppp;
if (!ppp)
return -EINVAL;
memset(&ppp->lcp, 0, sizeof(ppp->lcp));
memset(&ppp->ipcp, 0, sizeof(ppp->ipcp));
memset(&ppp->ip6cp, 0, sizeof(ppp->ip6cp));
ppp->ppp_state = PPPS_DEAD;
ppp->out_asyncmap = 0;
ppp->out_lcp_opts = BIT_MRU | BIT_MAGIC | BIT_PFCOMP | BIT_ACCOMP | BIT_MRU_COAX;
ppp->check_http_response = 0;
switch (ppp->encap) {
case PPP_ENCAP_F5:
ppp->encap_len = 4;
break;
case PPP_ENCAP_FORTINET:
/* XX: Fortinet server rejects asyncmap and header compression. Don't blame me. */
ppp->out_lcp_opts &= ~(BIT_PFCOMP | BIT_ACCOMP);
ppp->encap_len = 6;
break;
case PPP_ENCAP_F5_HDLC:
case PPP_ENCAP_RFC1662_HDLC:
ppp->encap_len = 0;
ppp->hdlc = 1;
break;
case PPP_ENCAP_RFC1661:
ppp->encap_len = 0;
break;
default:
free(ppp);
return -EINVAL;
}
if (ppp->hdlc) ppp->out_lcp_opts |= BIT_ASYNCMAP;
ppp->exp_ppp_hdr_size = 4; /* Address(1), Control(1), Proto(2) */
return 0;
}
static void print_ppp_state(struct openconnect_info *vpninfo, int level)
{
struct oc_ppp *ppp = vpninfo->ppp;
char buf4[20];
char buf6[40];
if (ppp->want_ipv4)
inet_ntop(AF_INET, &ppp->in_ipv4_addr, buf4, sizeof(buf4));
else
snprintf(buf4, sizeof(buf4), "none");
if (ppp->want_ipv6)
inet_ntop(AF_INET6, &ppp->in_ipv6_addr, buf6, sizeof(buf6));
else
snprintf(buf6, sizeof(buf6), "none");
vpn_progress(vpninfo, level, _("Current PPP state: %s (encap %s):\n"),
ppps_names[ppp->ppp_state], encap_names[ppp->encap]);
vpn_progress(vpninfo, level, _(" in: asyncmap=0x%08x, lcp_opts=%d, lcp_magic=0x%08x, ipv4=%s, ipv6=%s\n"),
ppp->in_asyncmap, ppp->in_lcp_opts, (unsigned)ntohl(ppp->in_lcp_magic),
buf4, buf6);
if (ppp->want_ipv4)
inet_ntop(AF_INET, &ppp->out_ipv4_addr, buf4, sizeof(buf4));
if (ppp->want_ipv6)
inet_ntop(AF_INET6, &ppp->out_ipv6_addr, buf6, sizeof(buf6));
vpn_progress(vpninfo, level, _(" out: asyncmap=0x%08x, lcp_opts=%d, lcp_magic=0x%08x, ipv4=%s, ipv6=%s, solicit_peerns=%d, got_peerns=%d\n"),
ppp->out_asyncmap, ppp->out_lcp_opts, (unsigned)ntohl(ppp->out_lcp_magic),
buf4, buf6, ppp->solicit_peerns, ppp->got_peerns);
}
static int buf_append_ppp_tlv(struct oc_text_buf *buf, int tag, int len, const void *data)
{
unsigned char b[2];
b[0] = tag;
b[1] = len + 2;
buf_append_bytes(buf, b, 2);
if (len)
buf_append_bytes(buf, data, len);
return b[1];
}
static int buf_append_ppp_tlv_be16(struct oc_text_buf *buf, int tag, uint16_t value)
{
uint16_t val_be;
store_be16(&val_be, value);
return buf_append_ppp_tlv(buf, tag, 2, &val_be);
}
static int buf_append_ppp_tlv_be32(struct oc_text_buf *buf, int tag, uint32_t value)
{
uint32_t val_be;
store_be32(&val_be, value);
return buf_append_ppp_tlv(buf, tag, 4, &val_be);
}
static int queue_config_packet(struct openconnect_info *vpninfo, uint16_t proto,
int id, int code, int len, const void *payload)
{
struct pkt *p = alloc_pkt(vpninfo, len + 4);
if (!p)
return -ENOMEM;
p->ppp.proto = proto;
p->data[0] = code;
p->data[1] = id;
p->len = 4 + len; /* payload length includes code, id, own 2 bytes */
store_be16(p->data + 2, p->len);
if (len)
memcpy(p->data + 4, payload, len);
queue_packet(&vpninfo->tcp_control_queue, p);
return 0;
}
#define PROTO_TAG_LEN(p, t, l) ((((uint32_t)(p)) << 16) | ((t) << 8) | (l))
static int handle_config_request(struct openconnect_info *vpninfo,
int proto, int id, unsigned char *payload, int len)
{
struct oc_ppp *ppp = vpninfo->ppp;
struct oc_text_buf *rejbuf = NULL, *nakbuf = NULL;
int ret;
struct oc_ncp *ncp;
unsigned char *p;
char abuf[MAX(INET_ADDRSTRLEN, INET6_ADDRSTRLEN)];
switch (proto) {
case PPP_LCP: ncp = &ppp->lcp; break;
case PPP_IPCP: ncp = &ppp->ipcp; break;
case PPP_IP6CP: ncp = &ppp->ip6cp; break;
default: return -EINVAL;
}
for (p = payload ; p+1 < payload+len && p+p[1] <= payload+len; p += p[1]) {
unsigned char t = p[0], l = p[1];
switch (PROTO_TAG_LEN(proto, t, l-2)) {
case PROTO_TAG_LEN(PPP_LCP, LCP_MRU, 2): {
int mru = load_be16(p + 2);
if ((ppp->out_lcp_opts & BIT_MRU_COAX) && mru < vpninfo->ip_info.mtu) {
/* XX: nak-offer our (larger) MTU to the server, but only try this once */
store_be16(p + 2, vpninfo->ip_info.mtu);
ppp->out_lcp_opts &= ~BIT_MRU_COAX;
vpn_progress(vpninfo, PRG_DEBUG,
_("Received MRU %d from server. Nak-offering larger MRU of %d (our MTU)\n"),
mru, vpninfo->ip_info.mtu);
goto nak;
} else {
vpninfo->ip_info.mtu = mru;
vpn_progress(vpninfo, PRG_DEBUG,
_("Received MRU %d from server. Setting our MTU to match.\n"),
mru);
}
break;
}
case PROTO_TAG_LEN(PPP_LCP, LCP_ASYNCMAP, 4):
ppp->in_asyncmap = load_be32(p+2);
vpn_progress(vpninfo, PRG_DEBUG,
_("Received asyncmap of 0x%08x from server\n"),
ppp->in_asyncmap);
break;
case PROTO_TAG_LEN(PPP_LCP, LCP_MAGIC, 4):
memcpy(&ppp->in_lcp_magic, p+2, 4);
vpn_progress(vpninfo, PRG_DEBUG,
_("Received magic number of 0x%08x from server\n"),
(unsigned)ntohl(ppp->in_lcp_magic));
break;
case PROTO_TAG_LEN(PPP_LCP, LCP_PFCOMP, 0):
vpn_progress(vpninfo, PRG_DEBUG,
_("Received protocol field compression from server\n"));
ppp->in_lcp_opts |= BIT_PFCOMP;
break;
case PROTO_TAG_LEN(PPP_LCP, LCP_ACCOMP, 0):
vpn_progress(vpninfo, PRG_DEBUG,
_("Received address and control field compression from server\n"));
ppp->in_lcp_opts |= BIT_ACCOMP;
break;
case PROTO_TAG_LEN(PPP_IPCP, IPCP_IPADDRS, 8):
/* XX: Ancient and deprecated. We're supposed to ignore it if we receive it, unless
* we've been Nak'ed. https://tools.ietf.org/html/rfc1332#section-3.1 */
vpn_progress(vpninfo, PRG_DEBUG,
_("Received deprecated IP-Addresses from server, ignoring\n"));
break;
case PROTO_TAG_LEN(PPP_IPCP, IPCP_IPCOMP, 4):
if (load_be16(p+2) == 0x002d) {
/* Van Jacobson TCP/IP compression. Includes an
* additional 2 payload bytes (Max-Slot-Id, Comp-Slot-Id) */
vpn_progress(vpninfo, PRG_DEBUG,
_("Received Van Jacobson TCP/IP compression from server\n"));
/* No. Just no. */
goto reject;
}
goto unknown;
case PROTO_TAG_LEN(PPP_IPCP, IPCP_IPADDR, 4):
memcpy(&ppp->in_ipv4_addr, p+2, 4);
vpn_progress(vpninfo, PRG_DEBUG,
_("Received peer IPv4 address %s from server\n"),
inet_ntop(AF_INET, &ppp->in_ipv4_addr, abuf, sizeof(abuf)));
break;
case PROTO_TAG_LEN(PPP_IP6CP, IP6CP_INT_ID, 8): {
unsigned char ipv6_ll[16] = {0xfe, 0x80, 0, 0, 0, 0, 0, 0};
/* XX: The server has allegedly sent us its link-local IPv6 address.
* However, on the only server I have access to which supports IPv6,
* this is just a random/garbage value, and `ping6 -I $TUNDEV $THIS_LL_ADDRESS`
* returns an "unreachable" result from the server's actual LL address,
* which is not sent over PPP configuration. This is probably just an
* ignorable vestige of before the days of IPv6 address autoconfiguration.
*/
memcpy(ipv6_ll + 8, p+2, 8);
memcpy(&ppp->in_ipv6_addr, ipv6_ll, 16);
vpn_progress(vpninfo, PRG_DEBUG,
_("Received peer IPv6 link-local address %s from server\n"),
inet_ntop(AF_INET6, &ppp->in_ipv6_addr, abuf, sizeof(abuf)));
break;
}
default:
unknown:
vpn_progress(vpninfo, PRG_DEBUG,
_("Received unknown %s TLV (tag %d, len %d+2) from server:\n"),
proto_names(proto), t, l-2);
dump_buf_hex(vpninfo, PRG_DEBUG, '<', p, (int)p[1]);
reject:
if (!rejbuf)
rejbuf = buf_alloc();
if (!rejbuf) {
ret = -ENOMEM;
goto out;
}
buf_append_bytes(rejbuf, p, l);
break;
nak:
if (!nakbuf)
nakbuf = buf_alloc();
if (!nakbuf) {
ret = -ENOMEM;
goto out;
}
buf_append_bytes(nakbuf, p, l);
}
}
ncp->state |= NCP_CONF_REQ_RECEIVED;
if (p != payload+len) {
vpn_progress(vpninfo, PRG_DEBUG,
_("Received %ld extra bytes at end of Config-Request:\n"), (long)(payload + len - p));
dump_buf_hex(vpninfo, PRG_DEBUG, '<', p, payload + len - p);
}
if (rejbuf) {
if ((ret = buf_error(rejbuf)))
goto out;
vpn_progress(vpninfo, PRG_DEBUG, _("Reject %s/id %d config from server\n"), proto_names(proto), id);
if ((ret = queue_config_packet(vpninfo, proto, id, CONFREJ, rejbuf->pos, rejbuf->data)) >= 0) {
ret = 0;
}
}
if (nakbuf) {
if ((ret = buf_error(nakbuf)))
goto out;
vpn_progress(vpninfo, PRG_DEBUG, _("Nak %s/id %d config from server\n"), proto_names(proto), id);
if ((ret = queue_config_packet(vpninfo, proto, id, CONFNAK, nakbuf->pos, nakbuf->data)) >= 0) {
ret = 0;
}
}
if (!rejbuf && !nakbuf) {
vpn_progress(vpninfo, PRG_DEBUG, _("Ack %s/id %d config from server\n"), proto_names(proto), id);
if ((ret = queue_config_packet(vpninfo, proto, id, CONFACK, len, payload)) >= 0) {
ncp->state |= NCP_CONF_ACK_SENT;
ret = 0;
}
}
out:
buf_free(rejbuf);
buf_free(nakbuf);
return ret;
}
static int queue_config_request(struct openconnect_info *vpninfo, int proto)
{
struct oc_ppp *ppp = vpninfo->ppp;
const uint32_t zero = 0;
int ret, id, b;
struct oc_ncp *ncp;
struct oc_text_buf *buf;
buf = buf_alloc();
ret = buf_ensure_space(buf, 64);
if (ret)
goto out;
switch (proto) {
case PPP_LCP:
ncp = &ppp->lcp;
if (!vpninfo->ip_info.mtu) {
int overhead = TLS_OVERHEAD + ppp->encap_len /* TLS and encapsulation overhead */
+ (ppp->hdlc ? 4 : 0) /* HDLC framing and FCS */
+ (ppp->out_lcp_opts & BIT_ACCOMP ? 0 : 2) /* PPP header AC fields */
+ (ppp->out_lcp_opts & BIT_PFCOMP ? 1 : 2); /* PPP header protocol field */
vpninfo->ip_info.mtu = calculate_mtu(vpninfo, 0 /* not UDP */, overhead, 0 /* no footer */, 1 /* no block padding */);
/* XX: HDLC fudge factor (average overhead on random payload is 1/128, we'll use 4x that) */
if (ppp->hdlc)
vpninfo->ip_info.mtu -= vpninfo->ip_info.mtu >> 5;
vpn_progress(vpninfo, PRG_INFO,
_("Requesting calculated MTU of %d\n"), vpninfo->ip_info.mtu);
}
if (ppp->out_lcp_opts & BIT_MRU)
buf_append_ppp_tlv_be16(buf, LCP_MRU, vpninfo->ip_info.mtu);
if (ppp->out_lcp_opts & BIT_ASYNCMAP)
buf_append_ppp_tlv_be32(buf, LCP_ASYNCMAP, ppp->out_asyncmap);
if (ppp->out_lcp_opts & BIT_MAGIC) {
ret = openconnect_random(&ppp->out_lcp_magic, sizeof(ppp->out_lcp_magic));
if (ret)
goto out;
buf_append_ppp_tlv(buf, LCP_MAGIC, 4, &ppp->out_lcp_magic);
}
if (ppp->out_lcp_opts & BIT_PFCOMP)
buf_append_ppp_tlv(buf, LCP_PFCOMP, 0, NULL);
if (ppp->out_lcp_opts & BIT_ACCOMP)
buf_append_ppp_tlv(buf, LCP_ACCOMP, 0, NULL);
break;
case PPP_IPCP:
ncp = &ppp->ipcp;
/* XX: send zero for IPv4/DNS/NBNS to request via NAK */
buf_append_ppp_tlv(buf, IPCP_IPADDR, 4, &ppp->out_ipv4_addr.s_addr);
/* XX: See ppp.h for why bitfields work here */
for (b=0; b<4; b++)
if (ppp->solicit_peerns & (1<<b))
buf_append_ppp_tlv(buf, IPCP_xNS_BASE + b, 4, &zero);
break;
case PPP_IP6CP:
ncp = &ppp->ip6cp;
/* Send zero here if we need a link-local IPv6 address, because
* we don't yet have a global IPv6 address. Otherwise, just send
* the interface bits of our global IPv6 address, to avoid getting
* a CONFREQ/CONFNAK/re-CONFREQ round trip */
buf_append_ppp_tlv(buf, IP6CP_INT_ID, 8, ppp->out_ipv6_addr.s6_addr + 8);
break;
default:
ret = -EINVAL;
goto out;
}
if ((ret = buf_error(buf)) != 0)
goto out;
id = ++ncp->id;
vpn_progress(vpninfo, PRG_DEBUG, _("Sending our %s/id %d config request to server\n"),
proto_names(proto), id);
if ((ret = queue_config_packet(vpninfo, proto, id, CONFREQ, buf->pos, buf->data)) >= 0) {
ncp->state |= NCP_CONF_REQ_SENT;
ret = 0;
}
out:
buf_free(buf);
return ret;
}
static int handle_config_rejnak(struct openconnect_info *vpninfo,
int proto, int id, int code, unsigned char *payload, int len)
{
struct oc_ppp *ppp = vpninfo->ppp;
struct oc_ncp *ncp;
unsigned char *p;
char abuf[MAX(INET_ADDRSTRLEN, INET6_ADDRSTRLEN)];
switch (proto) {
case PPP_LCP: ncp = &ppp->lcp; break;
case PPP_IPCP: ncp = &ppp->ipcp; break;
case PPP_IP6CP: ncp = &ppp->ip6cp; break;
default: return -EINVAL;
}
/* If it isn't a response to our latest ConfReq, we don't care */
if (id != ncp->id)
return 0;
for (p = payload ; p+1 < payload+len && p+p[1] <= payload+len; p += p[1]) {
unsigned char t = p[0], l = p[1];
switch (PROTO_TAG_LEN(proto, t, l-2)) {
case PROTO_TAG_LEN(PPP_LCP, LCP_MRU, 2):
/* XX: If this happens, should we try a smaller MRU? */
vpn_progress(vpninfo, PRG_DEBUG,
_("Server rejected/nak'ed LCP MRU option\n"));
ppp->out_lcp_opts &= ~BIT_MRU;
break;
case PROTO_TAG_LEN(PPP_LCP, LCP_ASYNCMAP, 4):
vpn_progress(vpninfo, PRG_DEBUG,
_("Server rejected/nak'ed LCP asyncmap option\n"));
ppp->out_asyncmap = ASYNCMAP_LCP;
ppp->out_lcp_opts &= ~BIT_ASYNCMAP;
break;
case PROTO_TAG_LEN(PPP_LCP, LCP_MAGIC, 4):
if (code == CONFNAK) {
/* XX: If this happens, we are will select a new magic number in
* our next CONFREQ, in case it's 1984 and our RS-232 nullmodem is
* looped back. (https://tools.ietf.org/html/rfc1661#section-6.4) */
} else {
vpn_progress(vpninfo, PRG_DEBUG,
_("Server rejected LCP magic option\n"));
ppp->out_lcp_opts &= ~BIT_MAGIC;
}
break;
case PROTO_TAG_LEN(PPP_LCP, LCP_PFCOMP, 0):
vpn_progress(vpninfo, PRG_DEBUG,
_("Server rejected/nak'ed LCP PFCOMP option\n"));
ppp->out_lcp_opts &= ~BIT_PFCOMP;
break;
case PROTO_TAG_LEN(PPP_LCP, LCP_ACCOMP, 0):
vpn_progress(vpninfo, PRG_DEBUG,
_("Server rejected/nak'ed LCP ACCOMP option\n"));
ppp->out_lcp_opts &= ~BIT_ACCOMP;
break;
case PROTO_TAG_LEN(PPP_IPCP, IPCP_IPADDR, 4): {
struct in_addr *a = (void *)(p + 2);
inet_ntop(AF_INET, a, abuf, sizeof(abuf));
if (code == CONFNAK && a->s_addr) {
vpn_progress(vpninfo, PRG_DEBUG,
_("Server nak-offered IPv4 address: %s\n"), abuf);
ppp->out_ipv4_addr = *a;
if (vpninfo->ip_info.addr) {
vpn_progress(vpninfo, PRG_ERR,
_("Server rejected Legacy IP address %s\n"),
vpninfo->ip_info.addr);
ppp->want_ipv4 = 0;
}
} else {
vpn_progress(vpninfo, PRG_DEBUG,
_("Server rejected/nak'ed our IPv4 address or request: %s\n"), abuf);
return -EINVAL;
}
break;
}
case PROTO_TAG_LEN(PPP_IPCP, IPCP_xNS_BASE + 0, 4):
case PROTO_TAG_LEN(PPP_IPCP, IPCP_xNS_BASE + 1, 4):
case PROTO_TAG_LEN(PPP_IPCP, IPCP_xNS_BASE + 2, 4):
case PROTO_TAG_LEN(PPP_IPCP, IPCP_xNS_BASE + 3, 4): {
struct in_addr *a = (void *)(p + 2);
/* XX: see ppp.h for why bitfields work here */
int is_dns = t&1;
int entry = (t&2)>>1;
inet_ntop(AF_INET, a, abuf, sizeof(abuf));
if (code == CONFNAK && a->s_addr) {
vpn_progress(vpninfo, PRG_DEBUG,
_("Server nak-offered IPCP request for %s[%d] server: %s\n"),
is_dns ? "DNS" : "NBNS", entry, abuf);
ppp->nameservers[t & 3] = *a;
ppp->got_peerns |= (1<<(t-IPCP_xNS_BASE));
} else {
vpn_progress(vpninfo, PRG_DEBUG,
_("Server rejected/nak'ed IPCP request for %s[%d] server\n"),
is_dns ? "DNS" : "NBNS", entry);
}
/* Stop soliciting */
ppp->solicit_peerns &= ~(1<<(t-IPCP_xNS_BASE));
break;
}
case PROTO_TAG_LEN(PPP_IP6CP, IP6CP_INT_ID, 8): {
uint64_t *val = (void *)(p + 2);
if (code == CONFNAK && *val != 0) {
unsigned char ipv6_ll[16] = {0xfe, 0x80, 0, 0, 0, 0, 0, 0};
memcpy(ipv6_ll + 8, val, 8);
inet_ntop(AF_INET6, ipv6_ll, abuf, sizeof(abuf));
vpn_progress(vpninfo, PRG_DEBUG,
_("Server nak-offered IPv6 link-local address %s\n"), abuf);
/* If we don't already have a valid global IPv6 address, then we are
* supposed to use this one to create a valid link-local IPv6
* address to allow autoconfiguration (https://tools.ietf.org/html/rfc5072)
*/
memcpy(&ppp->out_ipv6_addr, ipv6_ll, 16);
} else {
vpn_progress(vpninfo, PRG_INFO,
_("Server rejected/nak'ed our IPv6 interface identifier\n"));
ppp->want_ipv6 = 0;
return 0;
}
break;
}
default:
vpn_progress(vpninfo, PRG_DEBUG,
_("Server rejected/nak'ed %s TLV (tag %d, len %d+2)\n"),
proto_names(proto), t, l-2);
dump_buf_hex(vpninfo, PRG_DEBUG, '<', p, (int)p[1]);
/* XX: Should abort negotiation */
return -EINVAL;
}
}
if (p != payload+len) {
vpn_progress(vpninfo, PRG_DEBUG,
_("Received %ld extra bytes at end of Config-Reject:\n"), (long)(payload + len - p));
dump_buf_hex(vpninfo, PRG_DEBUG, '<', p, payload + len - p);
}
return queue_config_request(vpninfo, proto);
}
static int handle_config_packet(struct openconnect_info *vpninfo,
uint16_t proto, unsigned char *p, int len)
{
struct oc_ppp *ppp = vpninfo->ppp;
int code = p[0], id = p[1];
int ret = 0, add_state = 0;
/* XX: The NCP header consist of 4 bytes: u8 code, u8 id, u16 length (length includes this header) */
if (load_be16(p + 2) > len) {
vpn_progress(vpninfo, PRG_ERR, "PPP config packet too short (header says %d bytes, received %d)\n", load_be16(p+2), len);
dump_buf_hex(vpninfo, PRG_ERR, '<', p, len);
return -EINVAL;
} else if (load_be16(p + 2) < len) {
vpn_progress(vpninfo, PRG_DEBUG, "PPP config packet has junk at end (header says %d bytes, received %d)\n", load_be16(p+2), len);
len = load_be16(p + 2);
}
if (code > 0 && code <= 11)
vpn_progress(vpninfo, PRG_TRACE, _("Received %s/id %d %s from server\n"), proto_names(proto), id, lcp_names[code]);
switch (code) {
case CONFREQ:
ret = handle_config_request(vpninfo, proto, id, p + 4, len - 4);
break;
case CONFACK:
/* XX: we could verify that the ack/reply bytes match the request bytes,
* and the ID is the expected one, but it isn't 1992, so let's not.
*/
add_state = NCP_CONF_ACK_RECEIVED;
break;
case ECHOREQ:
if (ppp->ppp_state >= PPPS_OPENED)
ret = queue_config_packet(vpninfo, proto, id, ECHOREP, 4, &ppp->out_lcp_magic);
break;
case TERMREQ:
add_state = NCP_TERM_REQ_RECEIVED;
ret = queue_config_packet(vpninfo, proto, id, TERMACK, 0, NULL);
if (ret >= 0)
add_state = NCP_TERM_ACK_SENT;
goto set_quit_reason;
case TERMACK:
add_state = NCP_TERM_ACK_RECEIVED;
set_quit_reason:
if (!vpninfo->quit_reason && len > 4) {
vpninfo->quit_reason = strndup((char *)(p + 4), len - 4);
vpn_progress(vpninfo, PRG_ERR,
_("Server terminates with reason: %s\n"),
vpninfo->quit_reason);
}
ppp->ppp_state = PPPS_TERMINATE;
vpninfo->delay_close = NO_DELAY_CLOSE;
break;
case ECHOREP:
case DISCREQ:
break;
case CONFREJ:
case CONFNAK:
ret = handle_config_rejnak(vpninfo, proto, id, code, p + 4, len - 4);
break;
case PROTREJ:
/* Only handle rejection of IPCP or IP6CP */
if (proto != PPP_LCP || len < 6)
goto unknown;
proto = load_be16(p + 4);
if (proto == PPP_IPCP) ppp->want_ipv4 = 0;
else if (proto == PPP_IP6CP) ppp->want_ipv6 = 0;
else goto unknown;
vpn_progress(vpninfo, PRG_DEBUG,
_("Server rejected our request to configure IPv%d\n"),
proto == PPP_IP6CP ? 6 : 4);
break;
case CODEREJ:
default:
unknown:
ret = -EINVAL;
}
switch (proto) {
case PPP_LCP: ppp->lcp.state |= add_state; break;
case PPP_IPCP: ppp->ipcp.state |= add_state; break;
case PPP_IP6CP: ppp->ip6cp.state |= add_state; break;
default: return -EINVAL;
}
return ret;
}
static int handle_state_transition(struct openconnect_info *vpninfo, int dtls,
struct keepalive_info *kai, int *timeout)
{
struct oc_ppp *ppp = vpninfo->ppp;
time_t now = time(NULL);
int last_state = ppp->ppp_state, network, ret = 0;
switch (ppp->ppp_state) {
case PPPS_DEAD:
/* Prevent race conditions after recovering dead peer connection */
kai->last_rx = kai->last_tx = now;
/* Drop any failed outgoing packet from previous connection;
* we need to reconfigure before we can send data packets. */
free_pkt(vpninfo, vpninfo->current_ssl_pkt);
vpninfo->current_ssl_pkt = NULL;
vpninfo->partial_rec_size = 0;
ppp->ppp_state = PPPS_ESTABLISH;
/* fall through */
case PPPS_ESTABLISH:
if ((ppp->lcp.state & NCP_CONF_ACK_RECEIVED) && (ppp->lcp.state & NCP_CONF_ACK_SENT))
ppp->ppp_state = PPPS_OPENED;
else {
if (ka_check_deadline(timeout, now, ppp->lcp.last_req + 3)) {
ppp->lcp.last_req = now;
if ((ret = queue_config_request(vpninfo, PPP_LCP)) < 0)
goto out;
}
break;
}
/* fall through */
case PPPS_OPENED:
network = 1;
if (!ppp->want_ipv4 && !ppp->want_ipv6) {
vpninfo->quit_reason = "No network protocols configured";
return -EINVAL;
}
if (ppp->want_ipv4) {
if (!(ppp->ipcp.state & NCP_CONF_ACK_SENT) || !(ppp->ipcp.state & NCP_CONF_ACK_RECEIVED)) {
network = 0;
if (ka_check_deadline(timeout, now, ppp->ipcp.last_req + 3)) {
ppp->ipcp.last_req = now;
if ((ret = queue_config_request(vpninfo, PPP_IPCP)) < 0)
goto out;
}
}
}
if (ppp->want_ipv6) {
if (!(ppp->ip6cp.state & NCP_CONF_ACK_SENT) || !(ppp->ip6cp.state & NCP_CONF_ACK_RECEIVED)) {
network = 0;
if (ka_check_deadline(timeout, now, ppp->ip6cp.last_req + 3)) {
ppp->ip6cp.last_req = now;
if ((ret = queue_config_request(vpninfo, PPP_IP6CP)) < 0)
goto out;
}
}
}
if (!network)
break;
ppp->ppp_state = PPPS_NETWORK;
/* Ensure that we use the addresses we configured on PPP */
if (ppp->want_ipv4 && !vpninfo->ip_info.addr) {
vpninfo->ip_info.addr = add_option_ipaddr(&vpninfo->cstp_options, "ppp_ipv4",
AF_INET, &ppp->out_ipv4_addr);
}
/* Ensure that we use the addresses we configured on PPP */
if (ppp->want_ipv6 && !vpninfo->ip_info.addr6 && !vpninfo->ip_info.netmask6) {
vpninfo->ip_info.addr6 = add_option_ipaddr(&vpninfo->cstp_options, "ppp_ipv6",
AF_INET6, &ppp->out_ipv6_addr);
}
if (ppp->got_peerns & IPCP_NBNS0)
vpninfo->ip_info.nbns[0] = add_option_ipaddr(&vpninfo->cstp_options, "ppp_nbns0",
AF_INET, &ppp->nameservers[0]);
if (ppp->got_peerns & IPCP_DNS0)
vpninfo->ip_info.dns[0] = add_option_ipaddr(&vpninfo->cstp_options, "ppp_dns0",
AF_INET, &ppp->nameservers[1]);
if (ppp->got_peerns & IPCP_NBNS1)
vpninfo->ip_info.nbns[1] = add_option_ipaddr(&vpninfo->cstp_options, "ppp_nbns1",
AF_INET, &ppp->nameservers[2]);
if (ppp->got_peerns & IPCP_DNS1)
vpninfo->ip_info.dns[1] = add_option_ipaddr(&vpninfo->cstp_options, "ppp_dns1",
AF_INET, &ppp->nameservers[3]);
/* on close, we will need to send TERMREQ, then receive TERMACK */
vpninfo->delay_close = DELAY_CLOSE_IMMEDIATE_CALLBACK;
break;
case PPPS_NETWORK:
/* XX: When we pause and reconnect, we expect the auth cookie/session (external to the
* PPP layer) to remain valid, and to negotiate the same IP addresses on reconnection.
*
* However, most servers cancel our session or cancel our IP address allocation if we
* TERMINATE at the PPP layer, so we shouldn't do it when pausing.
*/
if (vpninfo->got_cancel_cmd ||
(vpninfo->got_pause_cmd && ppp->terminate_on_pause))
ppp->ppp_state = PPPS_TERMINATE;
else
break;
/* fall through */
case PPPS_TERMINATE:
/* XX: If server terminated, we already ACK'ed it */
if (ppp->lcp.state & NCP_TERM_REQ_RECEIVED)
return -EPIPE;
else if (!(ppp->lcp.state & NCP_TERM_ACK_RECEIVED)) {
/* We need to send a TERMREQ and wait for a TERMACK, but not keep
* retrying for ever if it fails. For TLS, which ought to be
* lossless, we send TERMREQ just once, wait for a second, and
* give up. For DTLS we try three times (with a second between
* them and give up if none of them elicit a TERMACK. */
if (!(ppp->lcp.state & NCP_TERM_REQ_SENT)) {
ppp->lcp.state |= NCP_TERM_REQ_SENT;
ppp->lcp.termreqs_sent = 1;
ppp->lcp.last_req = now;
(void) queue_config_packet(vpninfo, PPP_LCP, ++ppp->lcp.id, TERMREQ, 0, NULL);
vpninfo->delay_close = DELAY_CLOSE_WAIT; /* Wait 1s for TERMACK */
} else if (!ka_check_deadline(timeout, now, ppp->lcp.last_req + 1)) {
vpninfo->delay_close = DELAY_CLOSE_WAIT; /* Still waiting */