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/* (C) 2012 by Thomas Bertani <mail@thomasbertani.it>
*
* All Rights Reserved
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License along
* with this program; if not, write to the Free Software Foundation, Inc.,
* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
*
*/
#include <sys/file.h>
#include <termios.h>
#include <errno.h>
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <unistd.h>
#include <signal.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include "gsmtap.h"
static volatile int run = 1;
static int gsmtap_fd, serial_fd;
struct frame
{
unsigned char AppID, FCS, AppMsg[8192];
unsigned short AppMsgLength;
};
static void interrupt(int sign){ run = 0; }
static int serial_init(const char *serial_port)
{
struct termios t;
serial_fd = open(serial_port, O_RDWR | O_NOCTTY | O_NONBLOCK);
if (serial_fd < 0)
{
char errstr[50];
sprintf(errstr, "Failed to open serial port %s", serial_port);
perror(errstr);
return -1;
}
t.c_cflag = CBAUD | B115200 | CRTSCTS | CS8 | CREAD | CLOCAL;
t.c_cc[VMIN] = 255;
t.c_cc[VTIME] = 0;
tcsetattr(serial_fd, TCSAFLUSH, &t);
return 0;
}
static int serial_read(void *buf, size_t nbytes)
{
fd_set readfds;
FD_ZERO(&readfds);
FD_SET(serial_fd, &readfds);
struct timeval timeout = {0, 1000000};
int actual = select(serial_fd+1, &readfds, NULL, NULL, &timeout);
if(actual > 0)
{
actual = read(serial_fd, buf, nbytes);
if( actual == 0 )
{
run = 0;
return -1;
}
}
if((actual == -1) && (errno != EINTR))
{
perror("serial_read");
run = 0;
}
return actual;
}
static void gsmtap_open(const char *gsmtap_host)
{
struct sockaddr_in sin;
sin.sin_family= AF_INET;
sin.sin_port = htons(GSMTAP_UDP_PORT);
if (inet_aton(gsmtap_host, &sin.sin_addr) < 0) perror("parsing GSMTAP destination address");
gsmtap_fd = socket(AF_INET, SOCK_DGRAM, IPPROTO_UDP);
if (gsmtap_fd < 0) perror("GSMTAP socket initialization");
if (connect(gsmtap_fd, (struct sockaddr *)&sin, sizeof(sin)) < 0) perror("connecting GSMTAP socket");
}
void testgsmtap(unsigned char *AppMsg, unsigned short AppMsgLength)
{
int length = 0;
if ((AppMsg[0] == 0x03) && (AppMsg[1] < 0x04)) //trace messages except for GPRS RLC/MAC header and RATSCCH trace ones
{
int format = (AppMsg[2] >> 1 & 0b1111);
length = AppMsg[3] << 8 | AppMsg[4];
const size_t buf_len = sizeof(struct gsmtap_hdr) + length;
unsigned char buf[buf_len];
struct gsmtap_hdr *gh = (struct gsmtap_hdr *) buf;
memset(gh, 0, sizeof(*gh));
gh->version = GSMTAP_VERSION;
gh->hdr_len = sizeof(*gh)/4;
if ((AppMsg[2] & 1) == 1) gh->arfcn = htons(GSMTAP_ARFCN_F_UPLINK);
if ((format == 0) || (format == 2)) gh->type = GSMTAP_TYPE_UM_BURST;
else gh->type = GSMTAP_TYPE_UM;
gh->sub_type = GSMTAP_CHANNEL_UNKNOWN;
switch (format){
case 0: gh->sub_type = GSMTAP_BURST_NORMAL; break;
case 1: gh->sub_type = GSMTAP_CHANNEL_RACH; break;
case 2: gh->sub_type = GSMTAP_BURST_ACCESS; break;
case 3: gh->sub_type = GSMTAP_CHANNEL_BCCH; break;
case 4: gh->sub_type = GSMTAP_CHANNEL_PCH; break;
case 5: gh->sub_type = GSMTAP_CHANNEL_SDCCH; /*CBCH*/ break;
case 7: gh->sub_type = GSMTAP_CHANNEL_SDCCH; break;
case 8: gh->sub_type = GSMTAP_CHANNEL_ACCH | GSMTAP_CHANNEL_SDCCH; break;
case 9: gh->sub_type = GSMTAP_CHANNEL_TCH_F; break;
case 10: gh->sub_type = GSMTAP_CHANNEL_TCH_H; break;
case 11: gh->sub_type = GSMTAP_CHANNEL_CCCH; break;
case 12: gh->sub_type = GSMTAP_CHANNEL_AGCH; break;
default: gh->sub_type = GSMTAP_CHANNEL_UNKNOWN;
}
memcpy(buf+sizeof(*gh), AppMsg+5, length);
if (write(gsmtap_fd, buf, buf_len) < 0) perror("write gsmtap");
}
}
void req(unsigned char *msg, int length)
{
int sent = 0;
do
{
int ret = write(serial_fd, msg, length - sent);
if (ret < 0)
{
if (errno == EAGAIN)
{
usleep(1000);
continue;
}
break;
}
sent += ret;
msg += ret;
} while (sent < length);
if (sent != length) perror("Something went wrong while sending");
printf("Sent %dB frame!\n", length);
}
int main(int argc, char **argv)
{
struct stats { int packets, totalErrors, checksumErrors; } s;
struct frame f;
unsigned char actual, buf[3], fcs;
unsigned short i;
if (serial_init(argv[1]) < 0) return -1;
gsmtap_open(argv[2]);
printf("Press Ctrl+C to interrupt...\n");
signal(SIGINT, interrupt);
unsigned char myreq[] = {2, 0, 0, 6, 0, 31, 0, 0, 0, 63, 38, 3}; //LayerMessage-enable request
req(myreq, sizeof(myreq));
while (run)
{
if ((serial_read(buf, 1) == 1) && (buf[0] == 0x02))
{
s.packets++;
serial_read(buf, 3);
f.AppID = buf[0];
f.AppMsgLength = ((buf[1] & 0x1F) << 8) | buf[2];
fcs = f.AppID ^ buf[1] ^ buf[2];
if (f.AppMsgLength > 255) //FIXME: not yet implemented, actually we don't need it at all
{
s.packets--;
continue;
}
if (f.AppID != 0x00) continue; // we are just interested in parsing AppID == 0x00 (OTR) packets
serial_read(f.AppMsg, f.AppMsgLength);
for (i = 0; i < f.AppMsgLength; i++) fcs ^= f.AppMsg[i];
actual = serial_read(buf, 2);
if ((actual != 2) || (buf[1] != 0x03))
{
printf("(ERROR: ETX expected, got %d instead)\n", buf[1]);
s.totalErrors++;
continue;
}
printf("(OK %dB)", f.AppMsgLength);
f.FCS = buf[0];
if (fcs != f.FCS)
{
printf(" ~ WRONG CHECKSUM!!\n");
s.totalErrors++; s.checksumErrors++;
continue;
}
printf(" ~ AppMsg: [");
for (i = 0; i < f.AppMsgLength; i++) printf("%d ", f.AppMsg[i]);
printf("\b]\n");
testgsmtap(f.AppMsg, f.AppMsgLength);
}
}
myreq[9] = 0; myreq[10] = 25; //LayerMessage-disable request
req(myreq, sizeof(myreq));
printf("[*] Checksum errors: %d/%d | Total errors: %d/%d\n", s.checksumErrors, s.packets, s.totalErrors, s.packets);
return (s.totalErrors == 0) ? 0 : 1;
}
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