Greetings!
I wrote a ping library for Linux using raw sockets to use in my application (piping ping is not an option) and it is working fine if I use it without threads.
However if I try to ping multiple hosts (each host in a separate thread) I get mixed responses in both threads, e.g. thread 1 pinging 192.168.1.100 and thread 2 pinging 192.168.1.200: sometimes the answers are: "ping to 192.168.1.100: reply from 192.168.1.200", etc. Is there any way to prevent raw sockets from capturing packets that are't sent through them ?
This is my code:
ping.h
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#ifndef PING_H
#define PING_H
#include <stdio.h>
#include <unistd.h>
#include <stdlib.h>
#include <string.h>
#include <errno.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <sys/timex.h>
#include <arpa/inet.h>
#include <netdb.h>
#include <netinet/in.h>
#include <netinet/ip.h>
#include <netinet/ip_icmp.h>
typedef struct PingReply PingReply;
struct PingReply {
char *DAddr, *RAddr;
unsigned short icmp_type, icmp_code;
double msec;
char *error;
};
class Ping
{
public:
Ping(char *destination, unsigned int size, unsigned int timeout);
PingReply Send();
private:
unsigned int id, seq, size, timeout;
char *destination;
unsigned short ip_checksum(void* vdata,size_t length);
};
#endif // PING_H
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Ping.cpp
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#include "ping.h"
static int difference_micro(struct ntptimeval *bBefore,
struct ntptimeval *aAfter)
{
return (signed long long) aAfter->time.tv_sec * 1000000ll +
(signed long long) aAfter->time.tv_usec -
(signed long long) bBefore->time.tv_sec * 1000000ll -
(signed long long) bBefore->time.tv_usec;
}
Ping::Ping(char *destination, unsigned int size, unsigned int timeout)
{
this->destination = destination;
this->size = size;
this->timeout = timeout;
this->id = getpid();
this->seq = 0;
}
PingReply Ping::Send()
{
PingReply result;
result.DAddr = destination;
result.error = "";
struct ntptimeval start;
ntp_gettime(&start);
int sock = socket(AF_INET, SOCK_RAW, IPPROTO_ICMP);
if (sock==-1)
{
result.error = strerror(errno);
return result;
}
timeval tv_timeout;
tv_timeout.tv_sec = 0;
tv_timeout.tv_usec = timeout*1000;
int rc = setsockopt(sock, SOL_SOCKET, SO_RCVTIMEO, &tv_timeout, sizeof(timeval));
if (rc==-1)
{
result.error = strerror(errno);
close(sock);
return result;
}
seq++;
char *send_buffer = (char*)malloc(size);
if (!send_buffer)
{
result.error = "(ping.cpp:29: malloc() failed. Unable to allocate memory.";
close(sock);
return result;
}
memset(send_buffer,0,size);
struct icmphdr IcmpHeader;
IcmpHeader.type = ICMP_ECHO;
IcmpHeader.code = 0;
IcmpHeader.checksum = 0;
IcmpHeader.un.echo.id = htons(id);
IcmpHeader.un.echo.sequence = htons(seq);
IcmpHeader.checksum = this->ip_checksum(&IcmpHeader, sizeof(struct icmphdr));
memcpy(send_buffer, &IcmpHeader, sizeof(struct icmphdr));
struct sockaddr_in sa_dest;
sa_dest.sin_family = AF_INET;
sa_dest.sin_addr.s_addr = inet_addr(result.DAddr);
rc = sendto(sock, send_buffer, size, 0, (struct sockaddr*)&sa_dest, sizeof(struct sockaddr_in));
if (rc==-1)
{
result.error = strerror(errno);
free(send_buffer);
close(sock);
return result;
}
char *recv_buffer = (char*)malloc(size);
if (!recv_buffer)
{
free(send_buffer);
close(sock);
return result;
}
struct sockaddr_in sa_reply;
socklen_t sa_size = sizeof(struct sockaddr_in);
rc = recvfrom(sock, recv_buffer, size, 0, (struct sockaddr*)&sa_reply, &sa_size);
struct ntptimeval elapsed;
ntp_gettime(&elapsed);
if (rc==-1)
{
result.error = "Request timed out";
free(recv_buffer);
free(send_buffer);
close(sock);
return result;
}
result.RAddr = inet_ntoa(sa_reply.sin_addr);
struct icmphdr *IcmpReplyHeader = (struct icmphdr*)(recv_buffer+20); // ICMP header is after the IP Header which is 20 bytes long
if (IcmpHeader.un.echo.id != IcmpReplyHeader->un.echo.id) { result.error = "Request timed out"; } // If we capture an ICMP echo reply that's not for our PID, discard it
if (IcmpHeader.un.echo.sequence != IcmpReplyHeader->un.echo.sequence) { result.error = "Request timed out"; } // If we capture an old ICMP echo reply, discard it
result.icmp_type = IcmpReplyHeader->type;
result.icmp_code = IcmpReplyHeader->code;
result.msec = difference_micro(&start,&elapsed)*0.001;
free(recv_buffer); free(send_buffer); close(sock);
return result;
}
unsigned short Ping::ip_checksum(void* vdata,size_t length) {
// Cast the data pointer to one that can be indexed.
char* data=(char*)vdata;
// Initialise the accumulator.
uint32_t acc=0xffff;
// Handle complete 16-bit blocks.
size_t i;
for (i=0;i+1<length;i+=2) {
uint16_t word;
memcpy(&word,data+i,2);
acc+=ntohs(word);
if (acc>0xffff) {
acc-=0xffff;
}
}
// Handle any partial block at the end of the data.
if (length&1) {
uint16_t word=0;
memcpy(&word,data+length-1,1);
acc+=ntohs(word);
if (acc>0xffff) {
acc-=0xffff;
}
}
// Return the checksum in network byte order.
return htons(~acc);
}
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thread.h
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#include <QThread>
#include "ping.h"
class Thread : public QThread
{
public:
void run();
void setParams(char *ip, int size, int timeout);
private:
Ping *p;
PingReply pr;
};
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thread.cpp
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#include "threads.h"
void Thread::run()
{
printf("Spawning thread...\n");
for (int i=0;i<7;i++) {
pr = p->Send();
if (strlen(pr.error)) { printf("%s\n",pr.error); }
else {
printf("Ping %s: Reply from %s;Response type: %d;Response code: %d;Delay: %.2f\n",
pr.DAddr, pr.RAddr, pr.icmp_type, pr.icmp_code, pr.msec);
}
}
printf("Thread finished...\n");
exec();
}
void Thread::setParams(char *ip, int size, int timeout)
{
p = new Ping(ip,size,timeout);
}
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and
main.cpp
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#include "threads.h"
int main(int argc, char **argv)
{
if (argc < 3) { printf("Usage: %s <size> <timeout> <IP1> [IP2]...\n",argv[0]); }
for (int i=3;i<argc;i++) {
Thread *t = new Thread;
printf("Thread at %p\n", t);
t->setParams(argv[i],atoi(argv[1]),atoi(argv[2]));
t->start();
}
sleep(5);
return 0;
}
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