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-rw-r--r--mactelnet.h3
-rw-r--r--main.c107
2 files changed, 77 insertions, 33 deletions
diff --git a/mactelnet.h b/mactelnet.h
index 6176fa4..2a62353 100644
--- a/mactelnet.h
+++ b/mactelnet.h
@@ -19,6 +19,9 @@
#ifndef _MACTELNET_H
#define _MACTELNET_H 1
+#define MT_HEADER_LEN 22
+#define MT_CPHEADER_LEN 9
+
/* Packet type */
#define MT_PTYPE_SESSIONSTART 0
#define MT_PTYPE_DATA 1
diff --git a/main.c b/main.c
index e39df51..884cd3b 100644
--- a/main.c
+++ b/main.c
@@ -19,6 +19,7 @@
#include <stdlib.h>
#include <stdio.h>
#include <unistd.h>
+#include <errno.h>
#include <fcntl.h>
#include <signal.h>
#include <arpa/inet.h>
@@ -73,15 +74,18 @@ void sendAuthData(unsigned char *username, unsigned char *password) {
int databytes;
MD5_CTX c;
+ /* Concat string of 0 + password + encryptionkey */
md5data[0] = 0;
strncpy(md5data + 1, password, 82);
memcpy(md5data + 1 + strlen(password), encryptionkey, 16);
+ /* Generate md5 sum of md5data with a leading 0 */
MD5_Init(&c);
MD5_Update(&c, md5data, strlen(password) + 17);
MD5_Final(md5sum + 1, &c);
md5sum[0] = 0;
+ /* Send combined packet to server */
plen = initPacket(data, MT_PTYPE_DATA, srcmac, dstmac, sessionkey, outcounter);
databytes = plen;
plen += addControlPacket(data + plen, MT_CPTYPE_PASSWORD, md5sum, 17);
@@ -95,6 +99,7 @@ void sendAuthData(unsigned char *username, unsigned char *password) {
outcounter += plen - databytes;
+ /* TODO: handle result */
result = sendUDP(data, plen);
}
@@ -103,6 +108,7 @@ void sig_winch(int sig) {
unsigned char data[1500];
int result,plen,databytes;
+ /* terminal height/width has changed, inform server */
if (getTerminalSize(&width, &height) > 0) {
plen = initPacket(data, MT_PTYPE_DATA, srcmac, dstmac, sessionkey, outcounter);
databytes = plen;
@@ -112,6 +118,8 @@ void sig_winch(int sig) {
result = sendUDP(data, plen);
}
+
+ /* reinstate signal handler */
signal(SIGWINCH, sig_winch);
}
@@ -128,13 +136,15 @@ void handlePacket(unsigned char *data, int data_len) {
return;
}
+ /* Handle data packets */
if (pkthdr.ptype == MT_PTYPE_DATA) {
- char odata[200];
+ unsigned char odata[200];
int plen=0,result=0;
int rest = 0;
unsigned char *p = data;
- plen = initPacket(odata, MT_PTYPE_ACK, srcmac, dstmac, sessionkey, pkthdr.counter + (data_len - 22));
+ /* Always transmit ACKNOWLEDGE packets in response to DATA packets */
+ plen = initPacket(odata, MT_PTYPE_ACK, srcmac, dstmac, sessionkey, pkthdr.counter + (data_len - MT_HEADER_LEN));
result = sendUDP(odata, plen);
if (DEBUG)
@@ -142,22 +152,27 @@ void handlePacket(unsigned char *data, int data_len) {
/* Accept first packet, and all packets greater than incounter, and if counter has
wrapped around. */
- if (incounter == 0 || pkthdr.counter > incounter || incounter - pkthdr.counter > 32768)
+ if (incounter == 0 || pkthdr.counter > incounter || incounter - pkthdr.counter > 32768) {
incounter = pkthdr.counter;
- else {
+ } else {
/* Ignore double or old packets */
return;
}
- rest = data_len - 22;
- p += 22;
+ /* Calculate how much more there is in the packet */
+ rest = data_len - MT_HEADER_LEN;
+ p += MT_HEADER_LEN;
+
while (rest > 0) {
int read = 0;
struct mt_mactelnet_control_hdr cpkt;
+
+ /* Parse controlpacket data */
read = parseControlPacket(p, rest, &cpkt);
p += read;
rest -= read;
+ /* If we receive encryptionkey, transmit auth data back */
if (cpkt.cptype == MT_CPTYPE_ENCRYPTIONKEY) {
memcpy(encryptionkey, cpkt.data, cpkt.length);
sendAuthData(username, password);
@@ -165,14 +180,25 @@ void handlePacket(unsigned char *data, int data_len) {
printf("Received encryption key of %d characters\n", cpkt.length);
}
-
+
+ /* If the (remaining) data did not have a control-packet magic byte sequence,
+ the data is raw terminal data to be outputted to the terminal. */
else if (cpkt.cptype == MT_CPTYPE_PLAINDATA) {
cpkt.data[cpkt.length] = 0;
printf("%s", cpkt.data);
}
+ /* END_AUTH means that the user/password negotiation is done, and after this point
+ terminal data may arrive, so we set up the terminal to raw mode. */
else if (cpkt.cptype == MT_CPTYPE_END_AUTH) {
+ /* stop input buffering at all levels. Give full control of terminal to RouterOS */
+ rawTerm();
+ setvbuf(stdin, (char*)NULL, _IONBF, 0);
+
+ /* we have entered "terminal mode" */
terminalMode = 1;
+
+ /* Add resize signal handler */
signal(SIGWINCH, sig_winch);
}
}
@@ -180,12 +206,18 @@ void handlePacket(unsigned char *data, int data_len) {
else if (pkthdr.ptype == MT_PTYPE_ACK) {
/* TODO: If we were resubmitting lost messages, stop resubmitting here if received counter is correct. */
}
+
+ /* The server wants to terminate the connection, we have to oblige */
else if (pkthdr.ptype == MT_PTYPE_END) {
- char odata[200];
+ unsigned char odata[200];
int plen=0,result=0;
+
+ /* Acknowledge the disconnection by sending a END packet in return */
plen = initPacket(odata, MT_PTYPE_END, srcmac, dstmac, pkthdr.seskey, 0);
result = sendUDP(odata, plen);
+
fprintf(stderr, "Connection closed.\n");
+
/* exit */
running = 0;
} else {
@@ -199,9 +231,9 @@ void handlePacket(unsigned char *data, int data_len) {
int main (int argc, char **argv) {
int insockfd;
int result;
- char data[1500];
+ unsigned char data[1500];
struct sockaddr_in si_me;
- char buff[1500];
+ unsigned char buff[1500];
int plen = 0;
struct timeval timeout;
int keepalive_counter = 0;
@@ -228,17 +260,35 @@ int main (int argc, char **argv) {
strncpy(password, argv[4], 254);
}
+ /* Convert mac address string to ether_addr struct */
ether_aton_r(argv[2], (struct ether_addr *)dstmac);
+
+ /* Save username */
strncpy(username, argv[3], 254);
+ /* Seed randomizer */
srand(time(NULL));
+ if (geteuid() != 0) {
+ fprintf(stderr, "You need to have superuser abilities to use %s.\n", argv[0]);
+ return 1;
+ }
+
/* Transmit raw packets with this socket */
sockfd = socket(AF_PACKET, SOCK_RAW, htons(ETH_P_ALL));
+ if (sockfd < 0) {
+ perror("sockfd");
+ return 1;
+ }
/* Receive regular udp packets with this socket */
insockfd = socket(AF_INET, SOCK_DGRAM, IPPROTO_UDP);
+ if (insockfd < 0) {
+ perror("insockfd");
+ return 1;
+ }
+ /* Find device index number for specified interface */
deviceIndex = getDeviceIndex(sockfd, argv[1]);
if (deviceIndex < 0) {
fprintf(stderr, "Device %s not found.\n", argv[1]);
@@ -262,7 +312,7 @@ int main (int argc, char **argv) {
return 1;
}
- /* Set source port */
+ /* Set random source port */
sourceport = 1024 + (rand() % 1024);
/* Set up global info about the connection */
@@ -276,7 +326,7 @@ int main (int argc, char **argv) {
/* Bind to udp port */
if (bind(insockfd, (struct sockaddr *)&si_me, sizeof(si_me))==-1) {
- fprintf(stderr, "Error binding to %s:%d\n", inet_ntoa(si_me.sin_addr), sourceport);
+ fprintf(stderr, "Error binding to %s:%d, %s\n", inet_ntoa(si_me.sin_addr), sourceport, strerror(errno));
return 1;
}
@@ -290,11 +340,8 @@ int main (int argc, char **argv) {
plen = initPacket(data, MT_PTYPE_SESSIONSTART, srcmac, dstmac, sessionkey, 0);
result = sendUDP(data, plen);
- if (DEBUG)
- printf("Plen = %d, Send result: %d\n", plen, result);
- if (DEBUG)
- printf("Sessionkey: %d\n", sessionkey);
+ /* Try to connect with a timeout */
FD_ZERO(&read_fds);
FD_SET(insockfd, &read_fds);
timeout.tv_sec = 5;
@@ -307,8 +354,13 @@ int main (int argc, char **argv) {
}
result = recvfrom(insockfd, buff, 1400, 0, 0, 0);
+ if (result < 1) {
+ fprintf(stderr, "Connection failed.\n");
+ return 1;
+ }
printf("done\n");
+ /* Handle first received packet */
handlePacket(buff, result);
/*
@@ -317,23 +369,10 @@ int main (int argc, char **argv) {
*/
plen = initPacket(data, MT_PTYPE_DATA, srcmac, dstmac, sessionkey, 0);
plen += addControlPacket(data + plen, MT_CPTYPE_BEGINAUTH, NULL, 0);
- outcounter += 9;
+ outcounter += plen - MT_HEADER_LEN;
+ /* TODO: handle result of sendUDP */
result = sendUDP(data, plen);
- if (DEBUG)
- printf("Plen = %d, Send result: %d\n", plen, result);
-
- memset(buff, 0, 1500);
- result = recvfrom(insockfd, buff, 1500, 0, 0, 0);
- if (result < 1) {
- fprintf(stderr, "Connection failed.\n");
- return 1;
- }
- handlePacket(buff, result);
-
- /* stop input buffering at all levels. Give full control of terminal to RouterOS */
- rawTerm();
- setvbuf(stdin, (char*)NULL, _IONBF, 0);
while (running) {
int reads;
@@ -364,14 +403,16 @@ int main (int argc, char **argv) {
} else {
/* keepalive */
if ((keepalive_counter++ % 10) == 0) {
- char odata[22];
+ char odata[MT_HEADER_LEN];
int plen=0,result=0;
plen = initPacket(odata, MT_PTYPE_ACK, srcmac, dstmac, sessionkey, 0);
result = sendUDP(odata, plen);
}
}
}
- resetTerm();
+ if (terminalMode) {
+ resetTerm();
+ }
close(sockfd);
close(insockfd);
generated by cgit v1.2.3 (git 2.39.1) at 2025-03-04 09:19:15 +0000