fix for -v from Juergen Kammer

[l2tpns.git] / ppp.c

diff --git a/ppp.c b/ppp.c
index 3136d30..8e93f5d 100644 (file)
--- a/ppp.c
+++ b/ppp.c
@@ -1,5 +1,6 @@
 // L2TPNS PPP Stuff
 // L2TPNS PPP Stuff

-// $Id: ppp.c,v 1.4 2004-05-24 04:26:01 fred_nerk Exp $
+
+char const *cvs_id_ppp = "$Id: ppp.c,v 1.8 2004-07-11 07:57:35 bodea Exp $";

 
 #include <stdio.h>
 #include <string.h>
 
 #include <stdio.h>
 #include <string.h>


@@ -10,14 +11,15 @@
 #include "constants.h"
 #include "plugin.h"
 #include "util.h"
 #include "constants.h"
 #include "plugin.h"
 #include "util.h"

+#include "tbf.h"
+#include "cluster.h"

 
 extern tunnelt *tunnel;
 extern sessiont *session;
 extern radiust *radius;
 
 extern tunnelt *tunnel;
 extern sessiont *session;
 extern radiust *radius;

-extern int tapfd;
-extern char hostname[1000];
-extern struct Tstats *_statistics;
-extern unsigned long eth_tx;
+extern int tunfd;
+extern char hostname[];
+extern u32 eth_tx;

 extern time_t time_now;
 extern struct configt *config;
 
 extern time_t time_now;
 extern struct configt *config;
 


@@ -27,13 +29,13 @@ void processpap(tunnelidt t, sessionidt s, u8 * p, u16 l)
        char user[129];
        char pass[129];
 
        char user[129];
        char pass[129];
 

-#ifdef STAT_CALLS
-       STAT(call_processpap);
-#endif
+
+       CSTAT(call_processpap);
+

        log_hex(5, "PAP", p, l);
        if (l < 4)
        {
        log_hex(5, "PAP", p, l);
        if (l < 4)
        {

-               log(1, 0, s, t, "Short PAP %u bytes", l);
+               log(1, 0, s, t, "Short PAP %u bytes\n", l);

                STAT(tunnel_rx_errors);
                return ;
        }
                STAT(tunnel_rx_errors);
                return ;
        }


@@ -66,7 +68,11 @@ void processpap(tunnelidt t, sessionidt s, u8 * p, u16 l)
                // respond now, either no RADIUS available or already authenticated
                u8 b[MAXCONTROL];
                u8 id = p[1];
                // respond now, either no RADIUS available or already authenticated
                u8 b[MAXCONTROL];
                u8 id = p[1];

-               u8 *p = makeppp(b, 0, 0, t, s, PPPPAP);
+               u8 *p = makeppp(b, sizeof(b), 0, 0, t, s, PPPPAP);
+               if (!p) {       // Failed to make ppp header!
+                       log(1,0,0,0, "Failed to make PPP header in process pap!\n");
+                       return;
+               }

                if (session[s].ip)
                        *p = 2;              // ACK
                else
                if (session[s].ip)
                        *p = 2;              // ACK
                else


@@ -118,14 +124,17 @@ void processchap(tunnelidt t, sessionidt s, u8 * p, u16 l)
        u16 r;
        u16 len;
 
        u16 r;
        u16 len;
 

-#ifdef STAT_CALLS
-       STAT(call_processchap);
-#endif
+
+       CSTAT(call_processchap);
+

        log_hex(5, "CHAP", p, l);
        r = session[s].radius;
        if (!r)
        {
                log(1, 0, s, t, "Unexpected CHAP message\n");
        log_hex(5, "CHAP", p, l);
        r = session[s].radius;
        if (!r)
        {
                log(1, 0, s, t, "Unexpected CHAP message\n");

+
+// FIXME: Need to drop the session here.
+

                STAT(tunnel_rx_errors);
                return;
        }
                STAT(tunnel_rx_errors);
                return;
        }


@@ -206,21 +215,21 @@ char *ppp_lcp_types[] = {
        "DiscardRequest",
 };
 
        "DiscardRequest",
 };
 

-void dumplcp(char *p, int l)
+void dumplcp(u8 *p, int l)

 {
 {

-       signed int x = l - 3;
-       char *o = (p + 3);
+       signed int x = l - 4;
+       u8 *o = (p + 4);

 
        log_hex(5, "PPP LCP Packet", p, l);
 
        log_hex(5, "PPP LCP Packet", p, l);

-       log(4, 0, 0, 0, "PPP LCP Packet type %d (%s)\n", *p, ppp_lcp_types[(int)*p]);
+       log(4, 0, 0, 0, "PPP LCP Packet type %d (%s len %d)\n", *p, ppp_lcp_types[(int)*p], ntohs( ((u16 *) p)[1]) );

        log(4, 0, 0, 0, "Length: %d\n", l);
        if (*p != ConfigReq && *p != ConfigRej && *p != ConfigAck)
                return;
 
        while (x > 2)
        {
        log(4, 0, 0, 0, "Length: %d\n", l);
        if (*p != ConfigReq && *p != ConfigRej && *p != ConfigAck)
                return;
 
        while (x > 2)
        {

-               int type = *(u8 *)(o);
-               int length = *(u8 *)(o + 1);
+               int type = o[0];
+               int length = o[1];

                if (length == 0)
                {
                        log(4, 0, 0, 0, "       Option length is 0...\n");
                if (length == 0)
                {
                        log(4, 0, 0, 0, "       Option length is 0...\n");


@@ -245,18 +254,18 @@ void dumplcp(char *p, int l)
                                                        proto == 0xC223 ? "CHAP" : "PAP");
                                        break;
                                }
                                                        proto == 0xC223 ? "CHAP" : "PAP");
                                        break;
                                }

-                       case 5: // Magic-Number
-                               {
-                                       u32 magicno = ntohl(*(u32 *)(o + 2));
-                                       log(4, 0, 0, 0, "    %s %x\n", lcp_types[type], magicno);
-                                       break;
-                               }

                        case 4: // Quality-Protocol
                                {
                                        u32 qp = ntohl(*(u32 *)(o + 2));
                                        log(4, 0, 0, 0, "    %s %x\n", lcp_types[type], qp);
                                        break;
                                }
                        case 4: // Quality-Protocol
                                {
                                        u32 qp = ntohl(*(u32 *)(o + 2));
                                        log(4, 0, 0, 0, "    %s %x\n", lcp_types[type], qp);
                                        break;
                                }

+                       case 5: // Magic-Number
+                               {
+                                       u32 magicno = ntohl(*(u32 *)(o + 2));
+                                       log(4, 0, 0, 0, "    %s %x\n", lcp_types[type], magicno);
+                                       break;
+                               }

                        case 7: // Protocol-Field-Compression
                                {
                                        u32 pfc = ntohl(*(u32 *)(o + 2));
                        case 7: // Protocol-Field-Compression
                                {
                                        u32 pfc = ntohl(*(u32 *)(o + 2));


@@ -284,13 +293,13 @@ void processlcp(tunnelidt t, sessionidt s, u8 * p, u16 l)
        u8 b[MAXCONTROL];
        u8 *q = NULL;
 
        u8 b[MAXCONTROL];
        u8 *q = NULL;
 

-#ifdef STAT_CALLS
-       STAT(call_processlcp);
-#endif
+
+       CSTAT(call_processlcp);
+

        log_hex(5, "LCP", p, l);
        if (l < 4)
        {
        log_hex(5, "LCP", p, l);
        if (l < 4)
        {

-               log(1, session[s].ip, s, t, "Short LCP %d bytes", l);
+               log(1, session[s].ip, s, t, "Short LCP %d bytes\n", l);

                STAT(tunnel_rx_errors);
                return ;
        }
                STAT(tunnel_rx_errors);
                return ;
        }


@@ -300,15 +309,16 @@ void processlcp(tunnelidt t, sessionidt s, u8 * p, u16 l)
        }
        else if (*p == ConfigReq)
        {
        }
        else if (*p == ConfigReq)
        {

-               signed int x = l - 1;
-               char *o = (p + 1);
+               signed int x = l - 4;
+               u8 *o = (p + 4);

 
                log(3, session[s].ip, s, t, "LCP: ConfigReq (%d bytes)...\n", l);
 
                log(3, session[s].ip, s, t, "LCP: ConfigReq (%d bytes)...\n", l);

+               dumplcp(p, l);

 
                while (x > 2)
                {
 
                while (x > 2)
                {

-                       int type = *(u8 *)(o);
-                       int length = *(u8 *)(o + 1);
+                       int type = o[0];
+                       int length = o[1];

                        if (length == 0 || type == 0) break;
                        switch (type)
                        {
                        if (length == 0 || type == 0) break;
                        switch (type)
                        {


@@ -324,7 +334,11 @@ void processlcp(tunnelidt t, sessionidt s, u8 * p, u16 l)
 
                                                        if (!q)
                                                        {
 
                                                        if (!q)
                                                        {

-                                                               q = makeppp(b, p, l, t, s, PPPLCP);
+                                                               q = makeppp(b, sizeof(b), p, l, t, s, PPPLCP);
+                                                               if (!q) {
+                                                                       log(2, session[s].ip, s, t, " Failed to send packet.\n");
+                                                                       break;
+                                                               }

                                                                *q++ = ConfigNak;
                                                        }
                                                        memcpy(q, o, length);
                                                                *q++ = ConfigNak;
                                                        }
                                                        memcpy(q, o, length);


@@ -365,7 +379,11 @@ void processlcp(tunnelidt t, sessionidt s, u8 * p, u16 l)
                {
                        // Send back a ConfigAck
                        log(3, session[s].ip, s, t, "ConfigReq accepted, sending as Ack\n");
                {
                        // Send back a ConfigAck
                        log(3, session[s].ip, s, t, "ConfigReq accepted, sending as Ack\n");

-                       q = makeppp(b, p, l, t, s, PPPLCP);
+                       q = makeppp(b, sizeof(b), p, l, t, s, PPPLCP);
+                       if (!q) {
+                               log(3, session[s].ip, s, t, " failed to create packet.\n");
+                               return;
+                       }

                        *q = ConfigAck;
                        tunnelsend(b, l + (q - b), t);
                }
                        *q = ConfigAck;
                        tunnelsend(b, l + (q - b), t);
                }


@@ -376,7 +394,7 @@ void processlcp(tunnelidt t, sessionidt s, u8 * p, u16 l)
                        tunnelsend(b, l + (q - b), t);
 
                        log(3, session[s].ip, s, t, "Sending ConfigReq, requesting PAP login\n");
                        tunnelsend(b, l + (q - b), t);
 
                        log(3, session[s].ip, s, t, "Sending ConfigReq, requesting PAP login\n");

-                       q = makeppp(b, NULL, 0, t, s, PPPLCP);
+                       q = makeppp(b, sizeof(b), NULL, 0, t, s, PPPLCP);

                        *q++ = ConfigReq;
                        *(u8 *)(q++) = 3;
                        *(u8 *)(q++) = 4;
                        *q++ = ConfigReq;
                        *(u8 *)(q++) = 3;
                        *(u8 *)(q++) = 4;


@@ -393,20 +411,28 @@ void processlcp(tunnelidt t, sessionidt s, u8 * p, u16 l)
        else if (*p == TerminateReq)
        {
                *p = TerminateAck;     // close
        else if (*p == TerminateReq)
        {
                *p = TerminateAck;     // close

-               q = makeppp(b, p, l, t, s, PPPLCP);
+               q = makeppp(b, sizeof(b),  p, l, t, s, PPPLCP);
+               if (!q) {
+                       log(3, session[s].ip, s, t, "Failed to create PPP packet in processlcp.\n");
+                       return;
+               }

                log(3, session[s].ip, s, t, "LCP: Received TerminateReq. Sending TerminateAck\n");
                sessionshutdown(s, "Remote end closed connection.");
                tunnelsend(b, l + (q - b), t); // send it
        }
                log(3, session[s].ip, s, t, "LCP: Received TerminateReq. Sending TerminateAck\n");
                sessionshutdown(s, "Remote end closed connection.");
                tunnelsend(b, l + (q - b), t); // send it
        }

-       else if (*p == TerminateReq)
+       else if (*p == TerminateAck)

        {
        {

-               sessionshutdown(s, "Remote end closed connection.");
+               sessionshutdown(s, "Connection closed.");

        }
        else if (*p == EchoReq)
        {
                *p = EchoReply;      // reply
                *(u32 *) (p + 4) = htonl(session[s].magic); // our magic number
        }
        else if (*p == EchoReq)
        {
                *p = EchoReply;      // reply
                *(u32 *) (p + 4) = htonl(session[s].magic); // our magic number

-               q = makeppp(b, p, l, t, s, PPPLCP);
+               q = makeppp(b, sizeof(b), p, l, t, s, PPPLCP);
+               if (!q) {
+                       log(3, session[s].ip, s, t, " failed to send EchoReply.\n");
+                       return;
+               }

                log(5, session[s].ip, s, t, "LCP: Received EchoReq. Sending EchoReply\n");
                tunnelsend(b, l + (q - b), t); // send it
        }
                log(5, session[s].ip, s, t, "LCP: Received EchoReq. Sending EchoReply\n");
                tunnelsend(b, l + (q - b), t); // send it
        }


@@ -425,24 +451,27 @@ void processlcp(tunnelidt t, sessionidt s, u8 * p, u16 l)
 // Process IPCP messages
 void processipcp(tunnelidt t, sessionidt s, u8 * p, u16 l)
 {
 // Process IPCP messages
 void processipcp(tunnelidt t, sessionidt s, u8 * p, u16 l)
 {

-#ifdef STAT_CALLS
-       STAT(call_processipcp);
-#endif
+
+       CSTAT(call_processipcp);
+

        log_hex(5, "IPCP", p, l);
        if (l < 5)
        {
        log_hex(5, "IPCP", p, l);
        if (l < 5)
        {

-               log(1, 0, s, t, "Short IPCP %d bytes", l);
+               log(1, 0, s, t, "Short IPCP %d bytes\n", l);

                STAT(tunnel_rx_errors);
                return ;
        }
        if (*p == ConfigAck)
        {                          // happy with our IPCP
                u16 r = session[s].radius;
                STAT(tunnel_rx_errors);
                return ;
        }
        if (*p == ConfigAck)
        {                          // happy with our IPCP
                u16 r = session[s].radius;

-               if ((!r || radius[r].state == RADIUSIPCP) && !session[s].walled_garden)
+               if ((!r || radius[r].state == RADIUSIPCP) && !session[s].walled_garden) {

                        if (!r)
                                r = radiusnew(s);
                        if (r)
                                radiussend(r, RADIUSSTART); // send radius start, having got IPCP at last
                        if (!r)
                                r = radiusnew(s);
                        if (r)
                                radiussend(r, RADIUSSTART); // send radius start, having got IPCP at last

+               }
+               session[s].flags |= SF_IPCP_ACKED;
+

                return ;                 // done
        }
        if (*p != ConfigReq)
                return ;                 // done
        }
        if (*p != ConfigReq)


@@ -460,7 +489,7 @@ void processipcp(tunnelidt t, sessionidt s, u8 * p, u16 l)
        if (!session[s].ip)
        {
                log(3, 0, s, t, "Waiting on radius reply\n");
        if (!session[s].ip)
        {
                log(3, 0, s, t, "Waiting on radius reply\n");

-               return ;                   // have to wait on RADIUS eply
+               return ;                   // have to wait on RADIUS reply

        }
        // form a config reply quoting the IP in the session
        {
        }
        // form a config reply quoting the IP in the session
        {


@@ -480,7 +509,11 @@ void processipcp(tunnelidt t, sessionidt s, u8 * p, u16 l)
                {                       // reject
                        u16 n = 4;
                        i = p + l;
                {                       // reject
                        u16 n = 4;
                        i = p + l;

-                       q = makeppp(b, p, l, t, s, PPPIPCP);
+                       q = makeppp(b, sizeof(b), p, l, t, s, PPPIPCP);
+                       if (!q) {
+                               log(2, 0, s, t, "Failed to send IPCP.\n");
+                               return;
+                       }

                        *q = ConfigRej;
                        p += 4;
                        while (p < i && p[1])
                        *q = ConfigRej;
                        p += 4;
                        while (p < i && p[1])


@@ -529,60 +562,115 @@ void processipcp(tunnelidt t, sessionidt s, u8 * p, u16 l)
                                *(u32 *) (i + 2) = htonl(session[s].ip);
                                *p = ConfigNak;
                        }
                                *(u32 *) (i + 2) = htonl(session[s].ip);
                                *p = ConfigNak;
                        }

-                       q = makeppp(b, p, l, t, s, PPPIPCP);
+                       q = makeppp(b, sizeof(b), p, l, t, s, PPPIPCP);
+                       if (!q) {
+                               log(2, 0, s, t, " Failed to send IPCP packet.\n");
+                               return;
+                       }

                        tunnelsend(b, l + (q - b), t); // send it
                }
        }
 }
 
 // process IP packet received
                        tunnelsend(b, l + (q - b), t); // send it
                }
        }
 }
 
 // process IP packet received

+//
+// This MUST be called with at least 4 byte behind 'p'.
+// (i.e. this routine writes to p[-4]).

 void processipin(tunnelidt t, sessionidt s, u8 * p, u16 l)
 {
 void processipin(tunnelidt t, sessionidt s, u8 * p, u16 l)
 {

-#ifdef STAT_CALLS
-       STAT(call_processipin);
-#endif
+       ipt ip;
+
+
+       CSTAT(call_processipin);
+

        log_hex(5, "IP", p, l);
 
        log_hex(5, "IP", p, l);
 

+       ip = ntohl(*(u32 *)(p + 12));
+

        if (l > MAXETHER)
        {
        if (l > MAXETHER)
        {

-               log(1, *(u32 *)(p + 12), s, t, "IP packet too long %d\n", l);
+               log(1, ip, s, t, "IP packet too long %d\n", l);

                STAT(tunnel_rx_errors);
                return ;
        }
 
                STAT(tunnel_rx_errors);
                return ;
        }
 

-       session[s].cin += l;
-       session[s].total_cin += l;
-       session[s].pin++;
-       eth_tx += l;
+       // no spoof (do sessionbyip to handled statically routed subnets)
+       if (ip != session[s].ip && sessionbyip(htonl(ip)) != s)
+       {
+               log(5, ip, s, t, "Dropping packet with spoofed IP %s\n", inet_toa(htonl(ip)));
+               return;
+       }

 
        // Add on the tun header
        p -= 4;
        *(u32 *)p = htonl(0x00000800);
        l += 4;
 
 
        // Add on the tun header
        p -= 4;
        *(u32 *)p = htonl(0x00000800);
        l += 4;
 

+       if (session[s].tbf_in && !config->cluster_iam_master) { // Are we throttled and a slave?
+               master_throttle_packet(session[s].tbf_in, p, l); // Pass it to the master for handling.
+               return;
+       }
+
+       session[s].cin += l - 4;
+       session[s].total_cin += l - 4;
+       sess_count[s].cin += l - 4;
+
+       session[s].pin++;
+       eth_tx += l - 4;
+
+       if (session[s].snoop_ip && session[s].snoop_port)
+       {
+               // Snooping this session, send it to ASIO
+               snoop_send_packet(p, l, session[s].snoop_ip, session[s].snoop_port);
+       }
+       STAT(tun_tx_packets);
+       INC_STAT(tun_tx_bytes, l);
+
+       if (session[s].tbf_in && config->cluster_iam_master) { // Are we throttled and a master?? actually handle the throttled packets.
+               tbf_queue_packet(session[s].tbf_in, p, l);
+               return;
+       }
+

        // send to ethernet
        // send to ethernet

-       if (write(tapfd, p, l) < 0)
+       if (tun_write(p, l) < 0)

        {
        {

-               STAT(tap_tx_errors);
-               log(0, 0, s, t, "Error writing %d bytes to TAP device: %s (tapfd=%d, p=%p)\n",
-                       l, strerror(errno), tapfd, p);
+               STAT(tun_tx_errors);
+               log(0, 0, s, t, "Error writing %d bytes to TUN device: %s (tunfd=%d, p=%p)\n",
+                       l, strerror(errno), tunfd, p);

        }
 
        }
 

-       if (session[s].snoop)
+}
+
+//
+// Helper routine for the TBF filters.
+// Used to send queued data in from the user.
+//
+void send_ipin(sessionidt s, u8 *buf, int len)
+{
+       log_hex(5, "IP in throttled", buf, len);
+       if (write(tunfd, buf, len) < 0)

        {
        {

-               // Snooping this session, send it to ASIO
-               snoop_send_packet(p, l);
+               STAT(tun_tx_errors);
+               log(0, 0, 0, 0, "Error writing %d bytes to TUN device: %s (tunfd=%d, p=%p)\n",
+                       len, strerror(errno), tunfd, buf);

        }
        }

-       STAT(tap_tx_packets);
-       INC_STAT(tap_tx_bytes, l);
+
+       // Increment packet counters
+       session[s].cin += len - 4;
+       session[s].total_cin += len - 4;
+       sess_count[s].cin += len - 4;
+
+       session[s].pin++;
+       eth_tx += len - 4;

 }
 
 }
 

+

 // Process LCP messages
 void processccp(tunnelidt t, sessionidt s, u8 * p, u16 l)
 {
 // Process LCP messages
 void processccp(tunnelidt t, sessionidt s, u8 * p, u16 l)
 {

-#ifdef STAT_CALLS
-       STAT(call_processccp);
-#endif
+
+       CSTAT(call_processccp);
+

        log_hex(5, "CCP", p, l);
        if (l < 2 || (*p != ConfigReq && *p != TerminateReq))
        {
        log_hex(5, "CCP", p, l);
        if (l < 2 || (*p != ConfigReq && *p != TerminateReq))
        {


@@ -607,7 +695,11 @@ void processccp(tunnelidt t, sessionidt s, u8 * p, u16 l)
                }
                else
                        *p = TerminateAck;     // close
                }
                else
                        *p = TerminateAck;     // close

-               q = makeppp(b, p, l, t, s, PPPCCP);
+               q = makeppp(b, sizeof(b), p, l, t, s, PPPCCP);
+               if (!q) {
+                       log(1,0,0,0, "Failed to send CCP packet.\n");   
+                       return;
+               }

                tunnelsend(b, l + (q - b), t); // send it
        }
 }
                tunnelsend(b, l + (q - b), t); // send it
        }
 }


@@ -618,9 +710,9 @@ void sendchap(tunnelidt t, sessionidt s)
        u8 b[MAXCONTROL];
        u16 r = session[s].radius;
        u8 *q;
        u8 b[MAXCONTROL];
        u16 r = session[s].radius;
        u8 *q;

-#ifdef STAT_CALLS
-       STAT(call_sendchap);
-#endif
+
+       CSTAT(call_sendchap);
+

        if (!r)
        {
                log(1, 0, s, t, "No RADIUS to send challenge\n");
        if (!r)
        {
                log(1, 0, s, t, "No RADIUS to send challenge\n");


@@ -645,7 +737,11 @@ void sendchap(tunnelidt t, sessionidt s)
                STAT(tunnel_tx_errors);
                return ;
        }
                STAT(tunnel_tx_errors);
                return ;
        }

-       q = makeppp(b, 0, 0, t, s, PPPCHAP);
+       q = makeppp(b, sizeof(b), 0, 0, t, s, PPPCHAP);
+       if (!q) {
+               log(1, 0, s, t, "failed to send CHAP challenge.\n");
+               return;
+       }

        *q = 1;                      // challenhe
        q[1] = radius[r].id;         // ID
        q[4] = 16;                   // length
        *q = 1;                      // challenhe
        q[1] = radius[r].id;         // ID
        q[4] = 16;                   // length


@@ -658,24 +754,33 @@ void sendchap(tunnelidt t, sessionidt s)
 // fill in a L2TP message with a PPP frame,
 // copies existing PPP message and changes magic number if seen
 // returns start of PPP frame
 // fill in a L2TP message with a PPP frame,
 // copies existing PPP message and changes magic number if seen
 // returns start of PPP frame

-u8 *makeppp(u8 * b, u8 * p, int l, tunnelidt t, sessionidt s, u16 mtype)
+u8 *makeppp(u8 * b, int size, u8 * p, int l, tunnelidt t, sessionidt s, u16 mtype)

 {
 {

+
+       if (size < 12)
+               return NULL;    // Need more space than this!!
+

        *(u16 *) (b + 0) = htons(0x0002); // L2TP with no options
        *(u16 *) (b + 2) = htons(tunnel[t].far); // tunnel
        *(u16 *) (b + 4) = htons(session[s].far); // session
        b += 6;
        *(u16 *) (b + 0) = htons(0x0002); // L2TP with no options
        *(u16 *) (b + 2) = htons(tunnel[t].far); // tunnel
        *(u16 *) (b + 4) = htons(session[s].far); // session
        b += 6;

-       if (mtype != PPPLCP && !(session[s].flags & SESSIONACFC))
+       if (mtype != PPPLCP && !(session[s].l2tp_flags & SESSIONACFC))

        {
                *(u16 *) b = htons(0xFF03); // HDLC header
                b += 2;
        }
        {
                *(u16 *) b = htons(0xFF03); // HDLC header
                b += 2;
        }

-       if (mtype < 0x100 && session[s].flags & SESSIONPFC)
+       if (mtype < 0x100 && session[s].l2tp_flags & SESSIONPFC)

                *b++ = mtype;
        else
        {
                *(u16 *) b = htons(mtype);
                b += 2;
        }
                *b++ = mtype;
        else
        {
                *(u16 *) b = htons(mtype);
                b += 2;
        }

+
+       if (l + 12 > size) {
+               log(3,0,0,0, "Would have overflowed the buffer in makeppp: size %d, len %d.\n", size, l);
+               return NULL;    // Run out of room to hold the packet!
+       }

        if (p && l)
                memcpy(b, p, l);
        return b;
        if (p && l)
                memcpy(b, p, l);
        return b;


@@ -706,7 +811,11 @@ void initlcp(tunnelidt t, sessionidt s)
 {
        char b[500] = {0}, *q;
 
 {
        char b[500] = {0}, *q;
 

-       q = makeppp(b, NULL, 0, t, s, PPPLCP);
+       q = makeppp(b, sizeof(b), NULL, 0, t, s, PPPLCP);
+       if (!q) {
+               log(1, 0, s, t, "Failed to send LCP ConfigReq.\n");
+               return;
+       }

        log(4, 0, s, t, "Sending LCP ConfigReq for PAP\n");
        *q = ConfigReq;
        *(u8 *)(q + 1) = (time_now % 255) + 1; // ID
        log(4, 0, s, t, "Sending LCP ConfigReq for PAP\n");
        *q = ConfigReq;
        *(u8 *)(q + 1) = (time_now % 255) + 1; // ID