From 83c2de652b2b53a23b9e87d6eb3cb4085fe797c2 Mon Sep 17 00:00:00 2001
From: Mike Frysinger <vapier@gentoo.org>
Date: Fri, 3 Jan 2020 12:56:45 +0100
Subject: [PATCH 04/14] smarter killaddr

---
 pppd/options.c   |  8 ++++++++
 pppd/pppd.h      |  3 +++
 pppd/sys-linux.c | 42 +++++++++++++++++++++++++++++++++++++++---
 3 files changed, 50 insertions(+), 3 deletions(-)

diff --git a/pppd/options.c b/pppd/options.c
index f8d6c00..12d12fd 100644
--- a/pppd/options.c
+++ b/pppd/options.c
@@ -102,6 +102,9 @@ int	maxconnect = 0;		/* Maximum connect time */
 char	user[MAXNAMELEN];	/* Username for PAP */
 char	passwd[MAXSECRETLEN];	/* Password for PAP */
 bool	persist = 0;		/* Reopen link after it goes down */
+bool	killoldaddr = 0;	/* If our IP is reassigned on
+				   reconnect, kill active TCP
+				   connections using the old IP. */
 char	our_name[MAXNAMELEN];	/* Our name for authentication purposes */
 bool	demand = 0;		/* do dial-on-demand */
 char	*ipparam = NULL;	/* Extra parameter for ip up/down scripts */
@@ -252,6 +255,11 @@ option_t general_options[] = {
     { "demand", o_bool, &demand,
       "Dial on demand", OPT_INITONLY | 1, &persist },
 
+    { "killoldaddr", o_bool, &killoldaddr,
+      "Kill connections from an old source address", 1},
+    { "nokilloldaddr", o_bool,&killoldaddr,
+      "Don't kill connections from an old source address" },
+
     { "--version", o_special_noarg, (void *)showversion,
       "Show version number" },
     { "--help", o_special_noarg, (void *)showhelp,
diff --git a/pppd/pppd.h b/pppd/pppd.h
index 612902f..bdb8778 100644
--- a/pppd/pppd.h
+++ b/pppd/pppd.h
@@ -310,6 +310,9 @@ extern char	our_name[MAXNAMELEN];/* Our name for authentication purposes */
 extern char	remote_name[MAXNAMELEN]; /* Peer's name for authentication */
 extern bool	explicit_remote;/* remote_name specified with remotename opt */
 extern bool	demand;		/* Do dial-on-demand */
+extern bool	killoldaddr;	/* If our IP is reassigned on
+				   reconnect, kill active TCP
+				   connections using the old IP. */
 extern char	*ipparam;	/* Extra parameter for ip up/down scripts */
 extern bool	cryptpap;	/* Others' PAP passwords are encrypted */
 extern int	idle_time_limit;/* Shut down link if idle for this long */
diff --git a/pppd/sys-linux.c b/pppd/sys-linux.c
index 85b1512..95f5a72 100644
--- a/pppd/sys-linux.c
+++ b/pppd/sys-linux.c
@@ -172,6 +172,10 @@ struct in6_ifreq {
 static const eui64_t nulleui64;
 #endif /* INET6 */
 
+#ifndef SIOCKILLADDR
+#define SIOCKILLADDR	0x8939
+#endif
+
 /* We can get an EIO error on an ioctl if the modem has hung up */
 #define ok_error(num) ((num)==EIO)
 
@@ -220,6 +224,7 @@ static int	default_rt_repl_rest;	/* replace and restore old default rt */
 static u_int32_t proxy_arp_addr;	/* Addr for proxy arp entry added */
 static char proxy_arp_dev[16];		/* Device for proxy arp entry */
 static u_int32_t our_old_addr;		/* for detecting address changes */
+static u_int32_t our_current_addr;
 static int	dynaddr_set;		/* 1 if ip_dynaddr set */
 static int	looped;			/* 1 if using loop */
 static int	link_mtu;		/* mtu for the link (not bundle) */
@@ -566,6 +571,27 @@ int generic_establish_ppp (int fd)
     return -1;
 }
 
+static void do_killaddr(u_int32_t oldaddr)
+{
+    struct ifreq	ifr;
+
+    memset(&ifr,0,sizeof ifr);
+
+    SET_SA_FAMILY (ifr.ifr_addr,    AF_INET);
+    SET_SA_FAMILY (ifr.ifr_dstaddr, AF_INET);
+    SET_SA_FAMILY (ifr.ifr_netmask, AF_INET);
+
+    SIN_ADDR(ifr.ifr_addr) = oldaddr;
+
+    strlcpy(ifr.ifr_name, ifname, sizeof (ifr.ifr_name));
+
+    if(ioctl(sock_fd,SIOCKILLADDR,&ifr) < 0) {
+      if (!ok_error (errno))
+       error("ioctl(SIOCKILLADDR): %m(%d)", errno);
+      return;
+    }
+}
+
 /********************************************************************
  *
  * tty_disestablish_ppp - Restore the serial port to normal operation.
@@ -2747,9 +2773,14 @@ int sifaddr (int unit, u_int32_t our_adr, u_int32_t his_adr,
 	}
     }
 
-    /* set ip_dynaddr in demand mode if address changes */
-    if (demand && tune_kernel && !dynaddr_set
-	&& our_old_addr && our_old_addr != our_adr) {
+    if(persist && our_old_addr && our_old_addr != our_adr) {
+
+      if(killoldaddr)
+       do_killaddr(our_old_addr);
+
+
+      /* set ip_dynaddr in demand mode if address changes */
+      if (tune_kernel && !dynaddr_set) {
 	/* set ip_dynaddr if possible */
 	char *path;
 	int fd;
@@ -2761,7 +2792,10 @@ int sifaddr (int unit, u_int32_t our_adr, u_int32_t his_adr,
 	    close(fd);
 	}
 	dynaddr_set = 1;	/* only 1 attempt */
+      }
     }
+
+    our_current_addr = our_adr;
     our_old_addr = 0;
 
     return 1;
@@ -2818,6 +2852,8 @@ int cifaddr (int unit, u_int32_t our_adr, u_int32_t his_adr)
 
     our_old_addr = our_adr;
 
+    our_current_addr = 0;
+
     return 1;
 }
 
-- 
2.30.0