ppp: remove more unnecessary kernel checks

The ppp package can support all features since Linux 4.7.0 kernel.
Therefore, most kernel version checks can pass unconditionally on
OpenWrt v18.06 and later version. This patch can reduce the size
of ppp package by approximately 2.5 KB.

Signed-off-by: Shiji Yang <[email protected]>
Link: https://github.com/openwrt/openwrt/pull/16695
Signed-off-by: Christian Marangi <[email protected]>
(cherry picked from commit 3dbe730080e70e96990a5e89cbe2035adcca8d4b)
Link: https://github.com/openwrt/openwrt/pull/17097
Signed-off-by: Petr Štetiar <[email protected]>

package/network/services/ppp/patches/400-simplify_kernel_checks.patch

@@ -10,7 +10,14 @@ Signed-off-by: Jo-Philipp Wich <[email protected]>
 
 --- a/pppd/sys-linux.c
 +++ b/pppd/sys-linux.c
-@@ -231,7 +231,7 @@ static int driver_is_old       = 0;
+@@ -224,14 +224,10 @@ static fd_set in_fds;		/* set of fds tha
+ static int max_in_fd;		/* highest fd set in in_fds */
+ 
+ static int has_proxy_arp       = 0;
+-static int driver_version      = 0;
+-static int driver_modification = 0;
+-static int driver_patch        = 0;
+-static int driver_is_old       = 0;
  static int restore_term        = 0;	/* 1 => we've munged the terminal */
  static struct termios inittermios;	/* Initial TTY termios */
  
@@ -19,17 +26,18 @@ Signed-off-by: Jo-Philipp Wich <[email protected]>
  
  static char loop_name[20];
  static unsigned char inbuf[512]; /* buffer for chars read from loopback */
-@@ -250,8 +250,8 @@ static int	looped;			/* 1 if using loop
+@@ -249,9 +245,8 @@ static int	dynaddr_set;		/* 1 if ip_dyna
+ static int	looped;			/* 1 if using loop */
  static int	link_mtu;		/* mtu for the link (not bundle) */
  
- static struct utsname utsname;	/* for the kernel version */
+-static struct utsname utsname;	/* for the kernel version */
 -static int kernel_version;
  #define KVERSION(j,n,p)	((j)*1000000 + (n)*1000 + (p))
-+static const int kernel_version = KVERSION(2,6,37);
++static const int kernel_version = KVERSION(4,9,0);
  
  #define MAX_IFS		100
  
-@@ -1970,11 +1970,12 @@ int ccp_fatal_error (int unit)
+@@ -1970,11 +1965,12 @@ int ccp_fatal_error (int unit)
   *
   * path_to_procfs - find the path to the proc file system mount point
   */
@@ -44,7 +52,7 @@ Signed-off-by: Jo-Philipp Wich <[email protected]>
      struct mntent *mntent;
      FILE *fp;
  
-@@ -1996,6 +1997,7 @@ static char *path_to_procfs(const char *
+@@ -1996,6 +1992,7 @@ static char *path_to_procfs(const char *
  	    fclose (fp);
  	}
      }
@@ -52,35 +60,24 @@ Signed-off-by: Jo-Philipp Wich <[email protected]>
  
      strlcpy(proc_path + proc_path_len, tail,
  	    sizeof(proc_path) - proc_path_len);
-@@ -2895,15 +2897,19 @@ int ppp_check_kernel_support(void)
-     int    my_version, my_modification, my_patch;
-     int osmaj, osmin, ospatch;
+@@ -2889,6 +2886,8 @@ ppp_registered(void)
  
+ int ppp_check_kernel_support(void)
+ {
++    return 1; /* OpenWrt support ppp device "/dev/ppp" by default */
 +#if 0
-     /* get the kernel version now, since we are called before sys_init */
-     uname(&utsname);
-     osmaj = osmin = ospatch = 0;
-     sscanf(utsname.release, "%d.%d.%d", &osmaj, &osmin, &ospatch);
-     kernel_version = KVERSION(osmaj, osmin, ospatch);
-+#endif
- 
-     fd = open("/dev/ppp", O_RDWR);
-     if (fd >= 0) {
-+#if 0
- 	new_style_driver = 1;
+     int s, ok, fd;
+     struct ifreq ifr;
+     int    size;
+@@ -3016,6 +3015,7 @@ int ppp_check_kernel_support(void)
+     }
+     close(s);
+     return ok;
 +#endif
+ }
  
- 	/* XXX should get from driver */
- 	driver_version = 2;
-@@ -2963,6 +2969,7 @@ int ppp_check_kernel_support(void)
- 
-     if (ok && ((ifr.ifr_hwaddr.sa_family & ~0xFF) != ARPHRD_PPP))
- 	ok = 0;
-+	return ok;
- 
- /*
-  *  This is the PPP device. Validate the version of the driver at this
-@@ -3577,6 +3584,7 @@ get_pty(int *master_fdp, int *slave_fdp,
+ #ifndef HAVE_LOGWTMP
+@@ -3577,6 +3577,7 @@ get_pty(int *master_fdp, int *slave_fdp,
      }
  #endif /* TIOCGPTN */
  
@@ -88,7 +85,7 @@ Signed-off-by: Jo-Philipp Wich <[email protected]>
      if (sfd < 0) {
  	/* the old way - scan through the pty name space */
  	for (i = 0; i < 64; ++i) {
-@@ -3601,6 +3609,7 @@ get_pty(int *master_fdp, int *slave_fdp,
+@@ -3601,6 +3602,7 @@ get_pty(int *master_fdp, int *slave_fdp,
  	    }
  	}
      }
@@ -96,23 +93,35 @@ Signed-off-by: Jo-Philipp Wich <[email protected]>
  
      if (sfd < 0)
  	return 0;
+@@ -3716,6 +3718,7 @@ get_host_seed(void)
+ int
+ sys_check_options(void)
+ {
++#if 0
+     if (demand && driver_is_old) {
+ 	ppp_option_error("demand dialling is not supported by kernel driver "
+ 		     "version %d.%d.%d", driver_version, driver_modification,
+@@ -3726,6 +3729,7 @@ sys_check_options(void)
+ 	warn("Warning: multilink is not supported by the kernel driver");
+ 	multilink = 0;
+     }
++#endif
+     return 1;
+ }
+ 
 --- a/pppd/plugins/pppoatm/pppoatm.c
 +++ b/pppd/plugins/pppoatm/pppoatm.c
-@@ -179,14 +179,6 @@ static void disconnect_pppoatm(void)
- 
+@@ -180,10 +180,6 @@ static void disconnect_pppoatm(void)
  void plugin_init(void)
  {
--#ifdef linux
+ #ifdef linux
 -	extern int new_style_driver;	/* From sys-linux.c */
 -	if (!ppp_check_kernel_support() && !new_style_driver)
 -		fatal("Kernel doesn't support ppp_generic - "
 -		    "needed for PPPoATM");
--#else
--	fatal("No PPPoATM support on this OS");
--#endif
- 	ppp_add_options(pppoa_options);
- }
- 
+ #else
+ 	fatal("No PPPoATM support on this OS");
+ #endif
 --- a/pppd/plugins/pppoe/plugin.c
 +++ b/pppd/plugins/pppoe/plugin.c
 @@ -57,9 +57,6 @@ static char const RCSID[] =
@@ -138,17 +147,14 @@ Signed-off-by: Jo-Philipp Wich <[email protected]>
      info("PPPoE plugin from pppd %s", PPPD_VERSION);
 --- a/pppd/plugins/pppol2tp/pppol2tp.c
 +++ b/pppd/plugins/pppol2tp/pppol2tp.c
-@@ -500,12 +500,7 @@ static void pppol2tp_cleanup(void)
- 
+@@ -501,10 +501,6 @@ static void pppol2tp_cleanup(void)
  void plugin_init(void)
  {
--#if defined(__linux__)
+ #if defined(__linux__)
 -	extern int new_style_driver;	/* From sys-linux.c */
 -	if (!ppp_check_kernel_support() && !new_style_driver)
 -		fatal("Kernel doesn't support ppp_generic - "
 -		    "needed for PPPoL2TP");
--#else
-+#if !defined(__linux__)
+ #else
  	fatal("No PPPoL2TP support on this OS");
  #endif
- 	ppp_add_options(pppol2tp_options);