vpn: Adding support for latest pppd 2.5.0 release

The API has gone through a significant overhaul, and this change fixes any compile issues.
1) Fixes to configure.ac itself
2) Cleanup in pppd plugin itself

Adding a libppp-compat.h file to mask for any differences in the version.

3 files changed, 161 insertions, 23 deletions

diff --git a/configure.ac b/configure.ac
index ea7a2fac..e82ba469 100644
--- a/configure.ac
+++ b/configure.ac
@@ -135,14 +135,6 @@ AC_ARG_ENABLE(l2tp,
 	AC_HELP_STRING([--enable-l2tp], [enable l2tp support]),
 			[enable_l2tp=${enableval}], [enable_l2tp="no"])
 if (test "${enable_l2tp}" != "no"); then
-	if (test -z "${path_pppd}"); then
-		AC_PATH_PROG(PPPD, [pppd], [/usr/sbin/pppd], $PATH:/sbin:/usr/sbin)
-	else
-		PPPD="${path_pppd}"
-		AC_SUBST(PPPD)
-	fi
-	AC_CHECK_HEADERS(pppd/pppd.h, dummy=yes,
-			AC_MSG_ERROR(ppp header files are required))
 	if (test -z "${path_l2tp}"); then
 		AC_PATH_PROG(L2TP, [xl2tpd], [/usr/sbin/xl2tpd], $PATH:/sbin:/usr/sbin)
 	else
@@ -160,6 +152,18 @@ AC_ARG_ENABLE(pptp,
 	AC_HELP_STRING([--enable-pptp], [enable pptp support]),
 			[enable_pptp=${enableval}], [enable_pptp="no"])
 if (test "${enable_pptp}" != "no"); then
+	if (test -z "${path_pptp}"); then
+		AC_PATH_PROG(PPTP, [pptp], [/usr/sbin/pptp], $PATH:/sbin:/usr/sbin)
+	else
+		PPTP="${path_pptp}"
+		AC_SUBST(PPTP)
+	fi
+fi
+AM_CONDITIONAL(PPTP, test "${enable_pptp}" != "no")
+AM_CONDITIONAL(PPTP_BUILTIN, test "${enable_pptp}" = "builtin")
+
+if (test "${enable_pptp}" != "no" || test "${enable_l2tp}" != "no"); then
+
 	if (test -z "${path_pppd}"); then
 		AC_PATH_PROG(PPPD, [pppd], [/usr/sbin/pppd], $PATH:/sbin:/usr/sbin)
 	else
@@ -168,15 +172,23 @@ if (test "${enable_pptp}" != "no"); then
 	fi
 	AC_CHECK_HEADERS(pppd/pppd.h, dummy=yes,
 			AC_MSG_ERROR(ppp header files are required))
-	if (test -z "${path_pptp}"); then
-		AC_PATH_PROG(PPTP, [pptp], [/usr/sbin/pptp], $PATH:/sbin:/usr/sbin)
-	else
-		PPTP="${path_pptp}"
-		AC_SUBST(PPTP)
+	AC_CHECK_HEADERS([pppd/chap.h pppd/chap-new.h pppd/chap_ms.h])
+
+	PKG_CHECK_EXISTS([pppd],
+	    [AS_VAR_SET([pppd_pkgconfig_support],[yes])])
+
+	PPPD_VERSION=2.4.9
+	if test x"$pppd_pkgconfig_support" = xyes; then
+	    PPPD_VERSION=`$PKG_CONFIG --modversion pppd`
 	fi
+
+	AC_DEFINE_UNQUOTED([PPP_VERSION(x,y,z)],
+	    [((x & 0xFF) << 16 | (y & 0xFF) << 8 | (z & 0xFF) << 0)],
+	    [Macro to help determine the particular version of pppd])
+	PPP_VERSION=$(echo $PPPD_VERSION | sed -e "s/\./\,/g")
+	AC_DEFINE_UNQUOTED(WITH_PPP_VERSION, PPP_VERSION($PPP_VERSION),
+	    [The real version of pppd represented as an int])
 fi
-AM_CONDITIONAL(PPTP, test "${enable_pptp}" != "no")
-AM_CONDITIONAL(PPTP_BUILTIN, test "${enable_pptp}" = "builtin")
 
 AC_CHECK_HEADERS(resolv.h, dummy=yes,
 	AC_MSG_ERROR(resolver header files are required))
diff --git a/scripts/libppp-compat.h b/scripts/libppp-compat.h
new file mode 100644
index 00000000..eee1d09d
--- /dev/null
+++ b/scripts/libppp-compat.h
@@ -0,0 +1,127 @@
+/* Copyright (C) Eivind Naess, eivnaes@yahoo.com */
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+
+#ifndef __LIBPPP_COMPAT_H__
+#define __LIBPPP_COMPAT_H__
+
+/* Define USE_EAPTLS compile with EAP TLS support against older pppd headers,
+ * pppd >= 2.5.0 use PPP_WITH_EAPTLS and is defined in pppdconf.h */
+#define USE_EAPTLS 1
+
+/* Define INET6 to compile with IPv6 support against older pppd headers,
+ * pppd >= 2.5.0 use PPP_WITH_IPV6CP and is defined in pppdconf.h */
+#define INET6 1
+
+/* PPP < 2.5.0 defines and exports VERSION which overlaps with current package VERSION define.
+ * this silly macro magic is to work around that. */
+#undef VERSION
+#include <pppd/pppd.h>
+
+#ifndef PPPD_VERSION
+#define PPPD_VERSION VERSION
+#endif
+
+#include <pppd/fsm.h>
+#include <pppd/ccp.h>
+#include <pppd/eui64.h>
+#include <pppd/ipcp.h>
+#include <pppd/ipv6cp.h>
+#include <pppd/eap.h>
+#include <pppd/upap.h>
+
+#ifdef HAVE_PPPD_CHAP_H
+#include <pppd/chap.h>
+#endif
+
+#ifdef HAVE_PPPD_CHAP_NEW_H
+#include <pppd/chap-new.h>
+#endif
+
+#ifdef HAVE_PPPD_CHAP_MS_H
+#include <pppd/chap_ms.h>
+#endif
+
+#ifndef PPP_PROTO_CHAP
+#define PPP_PROTO_CHAP 0xc223
+#endif 
+
+#ifndef PPP_PROTO_EAP
+#define PPP_PROTO_EAP  0xc227
+#endif
+
+
+#if WITH_PPP_VERSION < PPP_VERSION(2,5,0)
+
+static inline bool
+debug_on (void)
+{
+	return debug;
+}
+
+static inline const char
+*ppp_ipparam (void)
+{
+	return ipparam;
+}
+
+static inline int
+ppp_ifunit (void)
+{
+	return ifunit;
+}
+
+static inline const char *
+ppp_ifname (void)
+{
+	return ifname;
+}
+
+static inline int
+ppp_get_mtu (int idx)
+{
+	return netif_get_mtu(idx);
+}
+
+typedef enum ppp_notify
+{
+    NF_PID_CHANGE,
+    NF_PHASE_CHANGE,
+    NF_EXIT,
+    NF_SIGNALED,
+    NF_IP_UP,
+    NF_IP_DOWN,
+    NF_IPV6_UP,
+    NF_IPV6_DOWN,
+    NF_AUTH_UP,
+    NF_LINK_DOWN,
+    NF_FORK,
+    NF_MAX_NOTIFY
+} ppp_notify_t;
+
+typedef void (ppp_notify_fn) (void *ctx, int arg);
+
+static inline void
+ppp_add_notify (ppp_notify_t type, ppp_notify_fn *func, void *ctx)
+{
+	struct notifier **list[NF_MAX_NOTIFY] = {
+		[NF_PID_CHANGE  ] = &pidchange,
+		[NF_PHASE_CHANGE] = &phasechange,
+		[NF_EXIT        ] = &exitnotify,
+		[NF_SIGNALED    ] = &sigreceived,
+		[NF_IP_UP       ] = &ip_up_notifier,
+		[NF_IP_DOWN     ] = &ip_down_notifier,
+		[NF_IPV6_UP     ] = &ipv6_up_notifier,
+		[NF_IPV6_DOWN   ] = &ipv6_down_notifier,
+		[NF_AUTH_UP     ] = &auth_up_notifier,
+		[NF_LINK_DOWN   ] = &link_down_notifier,
+		[NF_FORK        ] = &fork_notifier,
+	};
+
+	struct notifier **notify = list[type];
+	if (notify) {
+		add_notifier(notify, func, ctx);
+	}
+}
+
+#endif /* #if WITH_PPP_VERSION < PPP_VERSION(2,5,0) */
+#endif /* #if__LIBPPP_COMPAT_H__ */
diff --git a/scripts/libppp-plugin.c b/scripts/libppp-plugin.c
index 0dd8b471..61641b5b 100644
--- a/scripts/libppp-plugin.c
+++ b/scripts/libppp-plugin.c
@@ -29,14 +29,13 @@
 #include <sys/types.h>
 #include <sys/stat.h>
 #include <fcntl.h>
-#include <pppd/pppd.h>
-#include <pppd/fsm.h>
-#include <pppd/ipcp.h>
 #include <netinet/in.h>
 #include <arpa/inet.h>
 
 #include <dbus/dbus.h>
 
+#include "libppp-compat.h"
+
 #define INET_ADDRES_LEN (INET_ADDRSTRLEN + 5)
 #define INET_DNS_LEN	(2*INET_ADDRSTRLEN + 9)
 
@@ -47,7 +46,7 @@ static char *path;
 static DBusConnection *connection;
 static int prev_phase;
 
-char pppd_version[] = VERSION;
+char pppd_version[] = PPPD_VERSION;
 
 int plugin_init(void);
 
@@ -170,7 +169,7 @@ static void ppp_up(void *data, int arg)
 			DBUS_TYPE_STRING_AS_STRING DBUS_TYPE_STRING_AS_STRING
 			DBUS_DICT_ENTRY_END_CHAR_AS_STRING, &dict);
 
-	append(&dict, "INTERNAL_IFNAME", ifname);
+	append(&dict, "INTERNAL_IFNAME", ppp_ifname());
 
 	inet_ntop(AF_INET, &ipcp_gotoptions[0].ouraddr, buf, INET_ADDRSTRLEN);
 	append(&dict, "INTERNAL_IP4_ADDRESS", buf);
@@ -309,9 +308,9 @@ int plugin_init(void)
 	chap_check_hook = ppp_have_secret;
 	pap_check_hook = ppp_have_secret;
 
-	add_notifier(&ip_up_notifier, ppp_up, NULL);
-	add_notifier(&phasechange, ppp_phase_change, NULL);
-	add_notifier(&exitnotify, ppp_exit, connection);
+	ppp_add_notify(NF_IP_UP, ppp_up, NULL);
+	ppp_add_notify(NF_PHASE_CHANGE, ppp_phase_change, NULL);
+	ppp_add_notify(NF_EXIT, ppp_exit, connection);
 
 	return 0;
 }