ppp, adding support for compiling against pppd-2.5.0

This change does the following
* Adding in nm-pppd-compat.h to mask details regarding different
  versions of pppd.
* Fix the nm-pppd-plugin.c regarding differences in API between
  2.4.9 (current) and latet pppd 2.5.0 in master branch
* Additional fixes to the configure.ac to appropriately set defines used
  for compilation

6 files changed, 157 insertions, 23 deletions

diff --git a/Makefile.am b/Makefile.am
index cd30c7201e..4ff3ce2b26 100644
--- a/Makefile.am
+++ b/Makefile.am
@@ -3302,6 +3302,7 @@ src_core_ppp_nm_pppd_plugin_la_CPPFLAGS = \
 src_core_ppp_nm_pppd_plugin_la_SOURCES = \
 	src/core/ppp/nm-pppd-plugin.c \
 	src/core/ppp/nm-pppd-plugin.h \
+	src/core/ppp/nm-pppd-compat.h \
 	src/core/ppp/nm-ppp-status.h
 
 src_core_ppp_nm_pppd_plugin_la_LDFLAGS = \
diff --git a/config.h.meson b/config.h.meson
index 7337165082..a9fd32475a 100644
--- a/config.h.meson
+++ b/config.h.meson
@@ -236,6 +236,9 @@
 /* Define if you have PPP support */
 #mesondefine WITH_PPP
 
+/* Define if you have a more recent version of pppd */
+#mesondefine WITH_PPP_VERSION_2_5_OR_NEWER
+
 /* Define to path of pppd binary */
 #mesondefine PPPD_PATH
 
diff --git a/configure.ac b/configure.ac
index 1057b4e933..aa68cdc609 100644
--- a/configure.ac
+++ b/configure.ac
@@ -790,6 +790,11 @@ fi
 AC_DEFINE_UNQUOTED(PPPD_PATH, "$PPPD_PATH", [Define to path of pppd binary])
 AC_SUBST(PPPD_PATH)
 
+AC_CHECK_HEADERS(pppd/chap.h)
+if test "x$ac_cv_header_pppd_chap_h" = xyes; then
+	AC_DEFINE(WITH_PPP_VERSION_2_5_OR_NEWER, 1, "Defined if one has a recent version of pppd headers installed")
+fi
+
 # ModemManager1 with libmm-glib
 AC_ARG_WITH(modem-manager-1,
             AS_HELP_STRING([--with-modem-manager-1],
diff --git a/meson.build b/meson.build
index bed0702a1c..b967ccae5a 100644
--- a/meson.build
+++ b/meson.build
@@ -583,6 +583,10 @@ if enable_ppp
   if pppd_plugin_dir == ''
     pppd_plugin_dir = join_paths(nm_libdir, 'pppd', pppd_version)
   endif
+
+  if (pppd_dep.found())
+    config_h.set10('WITH_PPP_VERSION_2_5_OR_NEWER', 1)
+  endif
 endif
 config_h.set10('WITH_PPP', enable_ppp)
 
diff --git a/src/core/ppp/nm-pppd-compat.h b/src/core/ppp/nm-pppd-compat.h
new file mode 100644
index 0000000000..08bdedfab9
--- /dev/null
+++ b/src/core/ppp/nm-pppd-compat.h
@@ -0,0 +1,122 @@
+/* SPDX-License-Identifier: LGPL-2.1-or-later */
+/*
+ * Copyright (C) Eivind Næss, eivnaes@yahoo.com
+ */
+
+#ifndef __NM_PPPD_COMPAT_H__
+#define __NM_PPPD_COMPAT_H__
+
+/* 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/eui64.h>
+#include <pppd/ipcp.h>
+#include <pppd/ipv6cp.h>
+#include <pppd/upap.h>
+
+#ifdef WITH_PPP_VERSION_2_5_OR_NEWER
+#include <pppd/chap.h>
+#else
+#include <pppd/chap-new.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
+
+#ifndef WITH_PPP_VERSION_2_5_OR_NEWER
+
+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);
+}
+
+static inline void
+ppp_set_ifname(const char *new_name)
+{
+    g_strlcpy(ifname, new_name, IF_NAMESIZE);
+}
+
+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)
+{
+    static 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 /* #ifndef WITH_PPP_VERSION_2_5_OR_NEWER */
+#endif /* #ifdef __NM_PPPD_COMPAT_H__ */
diff --git a/src/core/ppp/nm-pppd-plugin.c b/src/core/ppp/nm-pppd-plugin.c
index e2e34d2aaf..59a2dcc94b 100644
--- a/src/core/ppp/nm-pppd-plugin.c
+++ b/src/core/ppp/nm-pppd-plugin.c
@@ -7,29 +7,23 @@
 #include <config.h>
 #define ___CONFIG_H__
 
-#include <pppd/pppd.h>
-#include <pppd/fsm.h>
-#include <pppd/ipcp.h>
 #include <sys/socket.h>
 #include <netinet/in.h>
 #include <net/if.h>
 #include <arpa/inet.h>
 #include <dlfcn.h>
+#include <glib.h>
 
-#define INET6
-#include <pppd/eui64.h>
-#include <pppd/ipv6cp.h>
+#include "nm-pppd-plugin.h"
+#include "nm-pppd-compat.h"
+#include "nm-ppp-status.h"
 
 #include "libnm-glib-aux/nm-default-glib.h"
-
 #include "nm-dbus-interface.h"
 
-#include "nm-pppd-plugin.h"
-#include "nm-ppp-status.h"
-
 int plugin_init(void);
 
-char pppd_version[] = VERSION;
+char pppd_version[] = PPPD_VERSION;
 
 static struct {
     GDBusConnection *dbus_connection;
@@ -125,7 +119,7 @@ nm_phasechange(int arg)
         char                       new_name[IF_NAMESIZE];
         int                        ifindex;
 
-        ifindex = if_nametoindex(ifname);
+        ifindex = if_nametoindex(ppp_ifname());
 
         /* Make a sync call to ensure that when the call
          * terminates the interface already has its final
@@ -143,9 +137,11 @@ nm_phasechange(int arg)
                                           NULL);
 
         /* Update the name in pppd if NM changed it */
-        if (if_indextoname(ifindex, new_name) && !nm_streq0(ifname, new_name)) {
-            g_message("nm-ppp-plugin: interface name changed from '%s' to '%s'", ifname, new_name);
-            g_strlcpy(ifname, new_name, IF_NAMESIZE);
+        if (if_indextoname(ifindex, new_name) && !nm_streq0(ppp_ifname(), new_name)) {
+            g_message("nm-ppp-plugin: interface name changed from '%s' to '%s'",
+                      ppp_ifname(),
+                      new_name);
+            ppp_set_ifname(new_name);
         }
     }
 }
@@ -166,7 +162,7 @@ nm_ip_up(void *data, int arg)
     ipcp_options    opts      = ipcp_gotoptions[0];
     ipcp_options    peer_opts = ipcp_hisoptions[0];
     GVariantBuilder builder;
-    guint32         pppd_made_up_address = htonl(0x0a404040 + ifunit);
+    guint32         pppd_made_up_address = htonl(0x0a404040 + ppp_ifunit());
 
     g_return_if_fail(G_IS_DBUS_CONNECTION(gl.dbus_connection));
 
@@ -186,7 +182,7 @@ nm_ip_up(void *data, int arg)
     g_variant_builder_add(&builder,
                           "{sv}",
                           NM_PPP_IP4_CONFIG_INTERFACE,
-                          g_variant_new_string(ifname));
+                          g_variant_new_string(ppp_ifname()));
 
     g_variant_builder_add(&builder,
                           "{sv}",
@@ -292,7 +288,7 @@ nm_ip6_up(void *data, int arg)
     g_variant_builder_add(&builder,
                           "{sv}",
                           NM_PPP_IP6_CONFIG_INTERFACE,
-                          g_variant_new_string(ifname));
+                          g_variant_new_string(ppp_ifname()));
     g_variant_builder_add(&builder, "{sv}", NM_PPP_IP6_CONFIG_OUR_IID, eui64_to_variant(go->ourid));
     g_variant_builder_add(&builder,
                           "{sv}",
@@ -393,6 +389,7 @@ nm_exit_notify(void *data, int arg)
 static void
 add_ip6_notifier(void)
 {
+#if WITH_PPP_VERSION < PPP_VERSION(2, 5, 0)
     static struct notifier **notifier  = NULL;
     static gsize             load_once = 0;
 
@@ -409,6 +406,9 @@ add_ip6_notifier(void)
         add_notifier(notifier, nm_ip6_up, NULL);
     else
         g_message("nm-ppp-plugin: no IPV6CP notifier support; IPv6 not available");
+#else
+    ppp_add_notify(NF_IPV6_UP, nm_ip6_up, NULL);
+#endif
 }
 
 int
@@ -427,17 +427,16 @@ plugin_init(void)
         return -1;
     }
 
-    gl.ipparam = g_strdup(ipparam);
+    gl.ipparam = g_strdup(ppp_ipparam());
 
     chap_passwd_hook = get_credentials;
     chap_check_hook  = get_chap_check;
     pap_passwd_hook  = get_credentials;
     pap_check_hook   = get_pap_check;
 
-    add_notifier(&phasechange, nm_phasechange_hook, NULL);
-    add_notifier(&ip_up_notifier, nm_ip_up, NULL);
-    add_notifier(&exitnotify, nm_exit_notify, NULL);
+    ppp_add_notify(NF_PHASE_CHANGE, nm_phasechange_hook, NULL);
+    ppp_add_notify(NF_IP_UP, nm_ip_up, NULL);
+    ppp_add_notify(NF_EXIT, nm_exit_notify, NULL);
     add_ip6_notifier();
-
     return 0;
 }