1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
|
--- a/pppd/demand.c
+++ b/pppd/demand.c
@@ -36,6 +36,8 @@
#include <errno.h>
#include <fcntl.h>
#include <netdb.h>
+#include <unistd.h>
+#include <syslog.h>
#include <sys/param.h>
#include <sys/types.h>
#include <sys/wait.h>
@@ -43,6 +45,8 @@
#include <sys/resource.h>
#include <sys/stat.h>
#include <sys/socket.h>
+#include <netinet/in.h>
+#include <arpa/inet.h>
#ifdef PPP_FILTER
#include <pcap-bpf.h>
#endif
@@ -221,6 +225,14 @@ loop_chars(p, n)
int c, rv;
rv = 0;
+
+/* check for synchronous connection... */
+
+ if ( (p[0] == 0xFF) && (p[1] == 0x03) ) {
+ rv = loop_frame(p,n);
+ return rv;
+ }
+
for (; n > 0; --n) {
c = *p++;
if (c == PPP_FLAG) {
@@ -299,17 +311,102 @@ loop_frame(frame, len)
* loopback, now that the real serial link is up.
*/
void
-demand_rexmit(proto)
+demand_rexmit(proto, newip)
int proto;
+ u_int32_t newip;
{
struct packet *pkt, *prev, *nextpkt;
+ unsigned short checksum;
+ unsigned short pkt_checksum = 0;
+ unsigned iphdr;
+ struct timeval tv;
+ char cv = 0;
+ char ipstr[16];
prev = NULL;
pkt = pend_q;
pend_q = NULL;
+ tv.tv_sec = 1;
+ tv.tv_usec = 0;
+ select(0,NULL,NULL,NULL,&tv); /* Sleep for 1 Seconds */
for (; pkt != NULL; pkt = nextpkt) {
nextpkt = pkt->next;
if (PPP_PROTOCOL(pkt->data) == proto) {
+ if ( (proto == PPP_IP) && newip ) {
+ /* Get old checksum */
+
+ iphdr = (pkt->data[4] & 15) << 2;
+ checksum = *((unsigned short *) (pkt->data+14));
+ if (checksum == 0xFFFF) {
+ checksum = 0;
+ }
+
+
+ if (pkt->data[13] == 17) {
+ pkt_checksum = *((unsigned short *) (pkt->data+10+iphdr));
+ if (pkt_checksum) {
+ cv = 1;
+ if (pkt_checksum == 0xFFFF) {
+ pkt_checksum = 0;
+ }
+ }
+ else {
+ cv = 0;
+ }
+ }
+
+ if (pkt->data[13] == 6) {
+ pkt_checksum = *((unsigned short *) (pkt->data+20+iphdr));
+ cv = 1;
+ if (pkt_checksum == 0xFFFF) {
+ pkt_checksum = 0;
+ }
+ }
+
+ /* Delete old Source-IP-Address */
+ checksum -= *((unsigned short *) (pkt->data+16)) ^ 0xFFFF;
+ checksum -= *((unsigned short *) (pkt->data+18)) ^ 0xFFFF;
+
+ pkt_checksum -= *((unsigned short *) (pkt->data+16)) ^ 0xFFFF;
+ pkt_checksum -= *((unsigned short *) (pkt->data+18)) ^ 0xFFFF;
+
+ /* Change Source-IP-Address */
+ * ((u_int32_t *) (pkt->data + 16)) = newip;
+
+ /* Add new Source-IP-Address */
+ checksum += *((unsigned short *) (pkt->data+16)) ^ 0xFFFF;
+ checksum += *((unsigned short *) (pkt->data+18)) ^ 0xFFFF;
+
+ pkt_checksum += *((unsigned short *) (pkt->data+16)) ^ 0xFFFF;
+ pkt_checksum += *((unsigned short *) (pkt->data+18)) ^ 0xFFFF;
+
+ /* Write new checksum */
+ if (!checksum) {
+ checksum = 0xFFFF;
+ }
+ *((unsigned short *) (pkt->data+14)) = checksum;
+ if (pkt->data[13] == 6) {
+ *((unsigned short *) (pkt->data+20+iphdr)) = pkt_checksum;
+ }
+ if (cv && (pkt->data[13] == 17) ) {
+ *((unsigned short *) (pkt->data+10+iphdr)) = pkt_checksum;
+ }
+
+ /* Log Packet */
+ strcpy(ipstr,inet_ntoa(*( (struct in_addr *) (pkt->data+16))));
+ if (pkt->data[13] == 1) {
+ syslog(LOG_INFO,"Open ICMP %s -> %s\n",
+ ipstr,
+ inet_ntoa(*( (struct in_addr *) (pkt->data+20))));
+ } else {
+ syslog(LOG_INFO,"Open %s %s:%d -> %s:%d\n",
+ pkt->data[13] == 6 ? "TCP" : "UDP",
+ ipstr,
+ ntohs(*( (short *) (pkt->data+iphdr+4))),
+ inet_ntoa(*( (struct in_addr *) (pkt->data+20))),
+ ntohs(*( (short *) (pkt->data+iphdr+6))));
+ }
+ }
output(0, pkt->data, pkt->length);
free(pkt);
} else {
--- a/pppd/ipcp.c
+++ b/pppd/ipcp.c
@@ -1864,7 +1864,7 @@ ipcp_up(f)
proxy_arp_set[f->unit] = 1;
}
- demand_rexmit(PPP_IP);
+ demand_rexmit(PPP_IP,go->ouraddr);
sifnpmode(f->unit, PPP_IP, NPMODE_PASS);
} else {
--- a/pppd/ipv6cp.c
+++ b/pppd/ipv6cp.c
@@ -1232,7 +1232,7 @@ ipv6cp_up(f)
}
}
- demand_rexmit(PPP_IPV6);
+ demand_rexmit(PPP_IPV6,0);
sifnpmode(f->unit, PPP_IPV6, NPMODE_PASS);
} else {
--- a/pppd/pppd.h
+++ b/pppd/pppd.h
@@ -566,7 +566,7 @@ void demand_conf __P((void)); /* config
void demand_block __P((void)); /* set all NPs to queue up packets */
void demand_unblock __P((void)); /* set all NPs to pass packets */
void demand_discard __P((void)); /* set all NPs to discard packets */
-void demand_rexmit __P((int)); /* retransmit saved frames for an NP */
+void demand_rexmit __P((int, u_int32_t)); /* retransmit saved frames for an NP*/
int loop_chars __P((unsigned char *, int)); /* process chars from loopback */
int loop_frame __P((unsigned char *, int)); /* should we bring link up? */
|
