Connect to cisco router with c++ via serial interface - c

Question

I want to connect to Cisco router from my c++ application.
Need it in order to get interface status.
My linux station (Ubuntu) and the router connected via serial interface.
connected from puty or minicom or Console Connections work.
for example:
root#test:/etc/minicom# cu -l /dev/ttyS0 -s 9600
Connected.
Router#show int summary
*: interface is up
IHQ: pkts in input hold queue IQD: pkts dropped from input queue
OHQ: pkts in output hold queue OQD: pkts dropped from output queue
RXBS: rx rate (bits/sec) RXPS: rx rate (pkts/sec)
TXBS: tx rate (bits/sec) TXPS: tx rate (pkts/sec)
TRTL: throttle count
Now i tried to do the same with C++ (or C) , but read hang.
My c code:
#include <stdio.h>
#include <string.h>
#include <fcntl.h>
#include <errno.h>
#include <termios.h>
#include <unistd.h>
#include <iostream>
#include<stdio.h>
#include<sys/ioctl.h>
#include<unistd.h>
#include<fcntl.h>
using namespace std;
int fd1;
int fd2;
char *buff, *buffer, *bufptr;
int wr, rd, nbytes, tries;
int configure_port(int fd) // configure the port
{
struct termios port_settings; // structure to store the port settings in
bzero(&port_settings, sizeof(port_settings));
cfsetispeed(&port_settings, B9600); // set baud rates
cfsetospeed(&port_settings, B9600);
port_settings.c_cflag &= ~PARENB; // set no parity, stop bits, data bits
port_settings.c_cflag &= ~CSTOPB;
port_settings.c_cflag &= ~CSIZE;
port_settings.c_cflag |= CS8;
tcsetattr(fd, TCSANOW, &port_settings); // apply the settings to the port
return (fd);
}
int main() {
fd1 = open("/dev/ttyS0", O_RDWR | O_NOCTTY | O_NDELAY);
if (fd1 == -1) {
perror("open_port: Unable to open /dev/ttyS0 – ");
} else {
fcntl(fd1, F_SETFL, 0);
}
printf("Port 1 has been sucessfully opened and %d is the file description\n",fd1);
configure_port(fd1);
wr = write(fd1, "\r", 1);
cout << " wr status " << wr << endl;
wr = write(fd1, "\r", 1);
cout << " wr status " << wr << endl;
wr = write(fd1, "ena\r", 4);
cout << " wr status " << wr << endl;
wr = write(fd1, "show int sum\r", 13);
cout << " wr status " << wr << endl;
rd = read(fd1, buff, 50);
cout << " rd status " << rd << endl;
cout << rd << endl;
return 0;
}

Answer 1

You aren't zeroing your port_settings struct first before modifying it. That's surely a bug, though it may not be the source of your problems. Have you tried building one of the dozens of "termios sample programs" available on the intnernet for comparison?

Answer 2

This work - probably sleep was missing.
#include <stdio.h>
#include <string.h>
#include <fcntl.h>
#include <errno.h>
#include <termios.h>
#include <unistd.h>
#include <iostream>
#include<stdio.h>
#include<sys/ioctl.h>
#include<unistd.h>
#include<fcntl.h>
using namespace std;
int set_interface_attribs(int fd, int speed, int parity) {
struct termios tty;
memset(&tty, 0, sizeof tty);
if (tcgetattr(fd, &tty) != 0) {
printf("err");//error_message("error %d from tcgetattr", errno);
return -1;
}
cfsetospeed(&tty, speed);
cfsetispeed(&tty, speed);
tty.c_cflag = (tty.c_cflag & ~CSIZE) | CS8; // 8-bit chars
// disable IGNBRK for mismatched speed tests; otherwise receive break
// as \000 chars
tty.c_iflag &= ~IGNBRK; // ignore break signal
tty.c_lflag = 0; // no signaling chars, no echo,
// no canonical processing
tty.c_oflag = 0; // no remapping, no delays
tty.c_cc[VMIN] = 0; // read doesn't block
tty.c_cc[VTIME] = 5; // 0.5 seconds read timeout
tty.c_iflag &= ~(IXON | IXOFF | IXANY); // shut off xon/xoff ctrl
tty.c_cflag |= (CLOCAL | CREAD); // ignore modem controls,
// enable reading
tty.c_cflag &= ~(PARENB | PARODD); // shut off parity
tty.c_cflag |= parity;
tty.c_cflag &= ~CSTOPB;
tty.c_cflag &= ~CRTSCTS;
if (tcsetattr(fd, TCSANOW, &tty) != 0) {
printf("err");//error_message("error %d from tcsetattr", errno);
return -1;
}
return 0;
}
void set_blocking(int fd, int should_block) {
struct termios tty;
memset(&tty, 0, sizeof tty);
if (tcgetattr(fd, &tty) != 0) {
printf("err");//error_message("error %d from tggetattr", errno);
return;
}
tty.c_cc[VMIN] = should_block ? 1 : 0;
tty.c_cc[VTIME] = 5; // 0.5 seconds read timeout
if (tcsetattr(fd, TCSANOW, &tty) != 0)
printf("err");//error_message("error %d setting term attributes", errno);
}
int main(int argc, char **argv) {
char *portname = "/dev/ttyS0";
int fd = open (portname, O_RDWR | O_NOCTTY | O_SYNC);
if (fd < 0) {
printf("err");//error_message("error %d opening %s: %s", errno, portname,strerror(errno));
return -1;
}
set_interface_attribs(fd, B9600, 0); // set speed to 115,200 bps, 8n1 (no parity)
set_blocking(fd, 0); // set no blocking
write(fd, "\r", 1); // send 7 character greeting
write(fd, "\r", 1);
usleep(100000);
char buf[1000];
write(fd, "ena\r", 4);
memset(&buf, 0, sizeof buf);
usleep(100000);
write(fd, "show int sum\r", 15);
sleep(1);
memset(&buf, 0, sizeof buf);
int n = read(fd, buf, sizeof buf); // read up to 100 characters if ready to read
cout << " n " << n << endl;
cout << " buf " << buf << endl;
close(fd);
}

Answer 3

You should use SNMP to get interface status/statistics instead of connecting to serial console.
This is exact purpose what was SNMP designed for.