I've this program which runs fine on Linux 2.6.34. While porting this program to 4.14, socket creation is giving error "Error: : Protocol not supported". As per http://man7.org/linux/man-pages/man7/netlink.7.html
NETLINK_NFLOG (up to and including Linux 3.16)
Netfilter/iptables ULOG.
Do we know what is the alternative in 4.14 ?
#include <stdlib.h>
#include <stdio.h>
#include <errno.h>
#include <string.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <sys/uio.h>
#include <pthread.h>
#include <netinet/ip.h>
#include <linux/types.h>
#include <linux/netlink.h>
int main()
{
struct sockaddr_nl addr;
int mypid;
int status;
int sockfd = -1;
/* mypid = getpid(); */
mypid = pthread_self();
sockfd = socket(AF_NETLINK, SOCK_RAW, NETLINK_NFLOG);
if (sockfd <= 0) {
printf("netlink socket() failed - rc:%d, errno:%d\n",
sockfd, errno);
perror("Error: ");
return (-1);
}
/* set up socket address */
memset(&addr, 0, sizeof (addr));
addr.nl_pid = mypid;
addr.nl_family = AF_NETLINK;
/*
nl_groups is the multicast
group ID to which the ULOG
messages will be sent.It
is bitmap of hexadecimal
format
*/
addr.nl_groups = 1;
/* bind socket to listen on
* multicast group 1 */
status = bind(sockfd, (struct sockaddr *)&addr, sizeof (addr));
if (status < 0) {
perror("bind:");
close(sockfd);
return (-1);
}
printf("socket bind successful\n");
close(sockfd);
return (0);
}
I tried to browse kernel source but couldn't identify.
I've below config
CONFIG_NETFILTER=y
# CONFIG_NETFILTER_ADVANCED is not set
CONFIG_NETFILTER_INGRESS=y
CONFIG_NETFILTER_NETLINK=y
CONFIG_NETFILTER_NETLINK_LOG=y
# CONFIG_NETFILTER_NETLINK_GLUE_CT is not set
CONFIG_NETFILTER_XTABLES=y
CONFIG_NETFILTER_XT_MARK=y
CONFIG_NETFILTER_XT_TARGET_CONNSECMARK=y
CONFIG_NETFILTER_XT_TARGET_LOG=y
CONFIG_NETFILTER_XT_NAT=y
# CONFIG_NETFILTER_XT_TARGET_NETMAP is not set
CONFIG_NETFILTER_XT_TARGET_NFLOG=y
# CONFIG_NETFILTER_XT_TARGET_REDIRECT is not set
CONFIG_NETFILTER_XT_TARGET_SECMARK=y
CONFIG_NETFILTER_XT_TARGET_TCPMSS=y
CONFIG_NETFILTER_XT_MATCH_ADDRTYPE=y
CONFIG_NETFILTER_XT_MATCH_CONNTRACK=y
CONFIG_NETFILTER_XT_MATCH_POLICY=y
CONFIG_NETFILTER_XT_MATCH_STATE=y
NETLINK_NFLOG (up to and including Linux 3.16)
see worked example in libnml
Related
I try to use setsockopt with the flag IPT_SO_SET_REPLACE but i keep getting the wired error from errno Protocol not available this is my code:
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sched.h>
#include <linux/sched.h>
#include <errno.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <linux/netlink.h>
#include <unistd.h>
#include <sys/ptrace.h>
#include <netinet/in.h>
#include <net/if.h>
#include <linux/netfilter_ipv4/ip_tables.h>
#include <fcntl.h>
int main(void) {
int sock;
int ret;
void *data;
size_t size;
struct ipt_replace *repl;
sock = socket(PF_INET, SOCK_RAW, IPPROTO_RAW);
if (sock == -1) {
perror("socket");
return -1;
}
size = sizeof(struct ipt_replace);
data = malloc(size); Protocol not available
if (data == NULL) {
perror("malloc");
return -1;
}
memset(data, 0, size);
repl = (struct ipt_replace *) data;
repl->num_counters = 0x1;
repl->size = 0xffffffff;
repl->valid_hooks = 0x1;
repl->num_entries = 0x1;
ret = setsockopt(sock, SOL_IP, IPT_SO_SET_REPLACE, (void *) data, size);
printf("\ndone %d\n", ret);
perror("error: ");
return 0;
}
this is the output :
sock:3
data:
size:92
done -1
error: : Protocol not available
Looking briefly at the kernel code, this would seem to indicate that the IP tables module isn't available (i.e. the kernel wasn't built with it configured, or it can't be found or loaded).
It appears to me that for a socket of the kind you created, the code flow is:
enter raw_setsockopt: level != SOL_RAW so...
call ip_setsockopt: level == SOL_IP but option isn't any of the IP_xxx options so...
call nf_setsockopt: Search loaded netfilter modules for one that has registered IPT_SO_SET_REPLACE.
I think the last must have failed, so you get ENOPROTOOPT back (== Protocol not available)
I'm learning Unix Network Programming in Chapter5, wait and waitpid functions. I test function wait. I run the server application firstly and then the client(repeat ./a.out several times). But the server can only accept the request one time and terminated. Errno is 4.
/* server.c
*
* gcc server.c -o server
* ./server & (run in background)
*/
#include <stdio.h>
#include <stdlib.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <strings.h>
#include <signal.h>
void sig_chld(int signum) // SIGCHLD handler
{
int stat;
pid_t pid;
pid = wait(&stat);
}
int main(void)
{
int listenfd;
int connfd;
struct sigaction act;
struct sockaddr_in addr;
socklen_t addrlen;
pid_t pid;
act.sa_handler = sig_chld; // register SIGCHLD handler
sigemptyset(&act.sa_mask);
act.sa_flags = 0;
sigaction(SIGCHLD, &act, NULL);
addrlen = sizeof(addr);
bzero(&addr, addrlen); // fill server address
addr.sin_family = AF_INET;
addr.sin_port = htons(8080);
inet_pton(AF_INET, "192.168.0.10", &addr.sin_addr.s_addr);
listenfd = socket(AF_INET, SOCK_STREAM, 0);
bind(listenfd, (struct sockaddr *)&addr, addrlen);
listen(listenfd, 5);
while (1) { // waiting for client request
connfd = accept(listenfd, (struct sockaddr *)&addr, &addrlen);
if (connfd < 0) {
printf("connect\n");
break;
}
pid = fork();
if (pid < 0) {
exit(-1);
} else if (pid == 0) { // child
close(listenfd);
write(connfd, "hello\n", 7);
exit(0);
}
else { // parent
close(connfd);
}
}
return 0;
}
/* client.c
*
* gcc client.c
* ./a.out (repeat several times)
*/
#include <stdio.h>
#include <stdlib.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <strings.h>
#include <errno.h>
#define MAXLINE 4096
int main(void)
{
char buf[1024];
int cliefd;
struct sockaddr_in servaddr;
socklen_t addrlen;
addrlen = sizeof(servaddr);
bzero(&servaddr, addrlen); // fill server address
servaddr.sin_family = AF_INET;
servaddr.sin_port = htons(8080);
inet_pton(AF_INET, "192.168.0.10", &servaddr.sin_addr.s_addr);
cliefd = socket(AF_INET, SOCK_STREAM, 0);
if (connect(cliefd, (struct sockaddr *)&servaddr, addrlen) < 0) {
printf("error: %d\n", errno);
exit(-1);
}
read(cliefd, buf, MAXLINE);
fputs(buf, stdout);
return 0;
}
errno value 4 is EINTR. This indicates that a system call was interrupted. In this case, the SIGCHLD is interrupting the accept system call. Keep reading further in that chapter. Below is a quote from it which specifically points that out for this particular example code:
Since the signal was caught by the parent while the parent was blocked in a slow system call (accept), the kernel causes accept to return an error of EINTR (interrupted system call). The parent does not handle this error so it aborts.
The purpose of this example is to show that when writing network programs that catch signals, we must be cognizant of interrupted system calls, and we must handle them.
It goes on further to explain how the signal can be set up to automatically restart interrupted system calls. In summary, set the SA_RESTART flag in the act.sa_flags field:
act.sa_flags |= SA_RESTART;
According to http://man7.org/linux/man-pages/man7/packet.7.html, there is a new option
PACKET_QDISC_BYPASS since linux 3.14. This has the potential of sending and receiving packets a lot faster.
Saw a sample code: https://github.com/netoptimizer/network-testing/blob/master/src/raw_packet_send.c, but unfortunately it doesn't have the code on sending packets.
I added some code to send packets but it has a problem with sendto.
# ./raw_packet_send p6p1 64
Lame RAW/PF_PACKET socket TX test program
Enabled kernel qdisc bypass
error sendto : Invalid argument
Not sure why. Here is the code (original raw_packet_send.c with my silly code). Please let me know how could make it work or point me to some good simple sample code. Thanks.
#include <stdio.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <stdlib.h>
#include <unistd.h>
#include <linux/if_packet.h>
#include <errno.h>
#include <sys/ioctl.h>
#include <net/if.h>
#include <netinet/in.h>
//#include <stdio.h>
//#include <sys/types.h>
//#include <sys/stat.h>
//#include <sys/socket.h>
//#include <sys/mman.h>
//#include <linux/filter.h>
//#include <ctype.h>
//#include <fcntl.h>
//#include <unistd.h>
//#include <bits/wordsize.h>
//#include <net/ethernet.h>
//#include <netinet/ip.h>
//#include <arpa/inet.h>
//#include <stdint.h>
//#include <string.h>
//#include <assert.h>
//#include <net/if.h>
//#include <inttypes.h>
//#include <poll.h>
//#include <unistd.h>
#ifndef PACKET_QDISC_BYPASS
#define PACKET_QDISC_BYPASS 20
#endif
#include "common_socket.h"
char pkt[2000] = {0x00, 1,2,3,4,0, 0,1,2,3,4,1, 8, 0};;
int len = 96;
char intfName[100] = "em1";
/* Avail in kernel >= 3.14
* in commit d346a3fae3 (packet: introduce PACKET_QDISC_BYPASS socket option)
*/
void set_sock_qdisc_bypass(int fd, int verbose)
{
int ret, val = 1;
ret = setsockopt(fd, SOL_PACKET, PACKET_QDISC_BYPASS, &val, sizeof(val));
if (ret < 0) {
printf("[DEBUG] %s(): err:%d errno:%d\n", __func__, ret, errno);
if (errno == ENOPROTOOPT) {
if (verbose)
printf("No kernel support for PACKET_QDISC_BYPASS"
" (kernel < 3.14?)\n");
} else {
perror("Cannot set PACKET_QDISC_BYPASS");
}
} else
if (verbose) printf("Enabled kernel qdisc bypass\n");
}
int pf_tx_socket(int ver)
{
int ret, val = 1;
/* Don't use proto htons(ETH_P_ALL) as we only want to transmit */
int sock = socket(PF_PACKET, SOCK_RAW, 0);
//int sock = socket(AF_INET,SOCK_PACKET,htons(3));
if (sock == -1) {
perror("Creation of RAW PF_SOCKET failed!\n");
exit(1);
}
ret = Setsockopt(sock, SOL_PACKET, PACKET_VERSION, &ver, sizeof(ver));
return sock;
}
void mybind(int sock, char *intf) {
struct ifreq ifr;
int rc;
memset((char*)&ifr, 0, sizeof(ifr));
snprintf(ifr.ifr_name, sizeof(ifr.ifr_name), intf);
if ((rc = setsockopt(sock, SOL_SOCKET, SO_BINDTODEVICE, (void *)&ifr, sizeof(ifr))) < 0)
{
perror("Server-setsockopt() error for SO_BINDTODEVICE");
printf("%s\n", strerror(errno));
close(sock);
exit(-1);
}
}
int flood (int sock) {
struct sockaddr intfAddrs;
char cmd[100];
int tmp;
memset((char*)&intfAddrs, 0, sizeof (struct sockaddr));
intfAddrs.sa_family = PF_PACKET;
strcpy((char*)(intfAddrs.sa_data), intfName);
sprintf(cmd, "ifconfig %s promisc", intfName); system(cmd);
while (1) {
while (1) {
tmp = sendto(sock, pkt, len, 0, &intfAddrs, sizeof(intfAddrs));
if (tmp != len) {perror("error sendto "); exit(0); }
}
}
}
int main(int argc, char **argv)
{
if (argc > 1) { strcpy(intfName, argv[1]); }
if (argc > 2) { len = atoi(argv[2]); }
printf("Lame RAW/PF_PACKET socket TX test program\n");
int sock = pf_tx_socket(0);
set_sock_qdisc_bypass(sock, 1);
mybind(sock, intfName);
flood(sock);
return 0;
}
I think you need to change from PF_PACKET to AF_PACKET (although it looks like PF_PACKET is an alias to AF_PACKET) but I don't have any success when using PF_PACKET.
This code works for me:
// Create a raw socket
sock_fd = socket(AF_PACKET, SOCK_RAW, htons(ETH_P_ALL));
if (sock_fd == -1) {
perror("Can't create AF_PACKET socket");
return EXIT_FAILURE;
}
// Check kernel version
static const int32_t sock_qdisc_bypass = 1;
int32_t sock_qdisc_ret = setsockopt(thd_opt->sock_fd, SOL_PACKET, PACKET_QDISC_BYPASS, &sock_qdisc_bypass, sizeof(sock_qdisc_bypass));
if (sock_qdisc_ret == -1) {
perror("Can't enable QDISC bypass on socket");
return EXIT_FAILURE;
}
This is from setup_socket_mmap() here
I have a small network consisting of 2 hosts (OS X and linux) with a switch between them. When I run the following pair of programs, the receiver (linux) doesn't see any multicast packets. However, when I run
tcpdump -i eth0 -s 512 udp
on the linux box, everything starts to work. Can someone tell me why running tcpdump enables this to work?
Note that both machines have IPv6 enabled (if that matters). The host addresses in the code are the IPv4 addresses of the local interfaces.
On the OS X machine, I run:
#include <time.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <arpa/inet.h>
#include <netinet/in.h>
#define BUFLEN 256
int s;
int count;
struct in_addr local_address;
struct sockaddr_in multicast_address;
char buffer[BUFLEN];
int
main (int argc, char *argv[]) {
int port = 12345;
int retval = 0;
char *host_ip = "192.168.1.31";
char *multicast_ip = "224.0.0.251";
count = (int)time(NULL);
s = socket(AF_INET, SOCK_DGRAM, 0);
printf("s=%d\n", s);
local_address.s_addr = inet_addr(host_ip);
retval = setsockopt(s, IPPROTO_IP, IP_MULTICAST_IF, (char *)&local_address, sizeof(local_address));
printf("setsockopt=%d\n", retval);
memset((char *)&multicast_address, 0, sizeof(multicast_address));
multicast_address.sin_family = AF_INET;
multicast_address.sin_addr.s_addr = inet_addr(multicast_ip);
multicast_address.sin_port = htons(port);
while (1) {
sprintf(buffer, "Message number %d", count);
count++;
retval = sendto(s, buffer, BUFLEN, 0, (struct sockaddr*)&multicast_address, sizeof(multicast_address));
printf("sendto=%d\n", retval);
sleep(3);
}
return 0;
}
On the linux box, I run:
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <arpa/inet.h>
#include <netinet/in.h>
#define BUFLEN 256
int s;
struct ip_mreq multicast_group;
struct sockaddr_in localSock;
char buffer[BUFLEN];
int
main(int argc, char *argv[]) {
int reuse = 1;
int retval = 0;
int port = 12345;
char *host_ip = "192.168.1.131";
char *multicast_ip = "224.0.0.251";
s = socket(AF_INET, SOCK_DGRAM, 0);
printf("s = %d\n", s);
setsockopt(s, SOL_SOCKET, SO_REUSEADDR, (char *)&reuse, sizeof(reuse));
printf("REUSEADDR = %d\n", retval);
memset((char *) &localSock, 0, sizeof(localSock));
localSock.sin_family = AF_INET;
localSock.sin_port = htons(port);
localSock.sin_addr.s_addr = INADDR_ANY;
retval = bind(s, (struct sockaddr*)&localSock, sizeof(localSock));
printf("bind = %d\n", retval);
multicast_group.imr_multiaddr.s_addr = inet_addr(multicast_ip);
multicast_group.imr_interface.s_addr = inet_addr(host_ip);
retval = setsockopt(s, IPPROTO_IP, IP_ADD_MEMBERSHIP, (char *)&multicast_group, sizeof(multicast_group));
printf("ADD_MEMBERSHIP = %d\n", retval);
while (1) {
retval = read(s, buffer, BUFLEN);
printf("%d => [%s]\n", retval, buffer);
}
return 0;
}
Thanks.
I am trying to communicate with TCP between a Qt program and a regular linux program. I have an existing linux client server program and I am trying to replace the server program with a Qt application. Here is the linux client code
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <netdb.h>
#include <unistd.h>
int main(int argc, char *argv[])
{
int sockfd, portno, n;
struct sockaddr_in serv_addr;
struct hostent *server;
char buffer[256];
portno = 9876;
sockfd = socket(AF_INET, SOCK_STREAM, 0);
if (sockfd < 0)
{
printf("ERROR opening socket");
return -1;
}
server = gethostbyname("localhost");
if (server == NULL)
{
printf("ERROR, no such host\n");
return -1;
}
memset((char *) &serv_addr,0,sizeof(serv_addr));
serv_addr.sin_family = AF_INET;
bcopy((char *)server->h_addr,
(char *)&serv_addr.sin_addr.s_addr,
server->h_length);
serv_addr.sin_port = htons(portno);
connect(sockfd,(sockaddr*)&serv_addr,sizeof(serv_addr));
sprintf(buffer,"This is a test\n");
n = write(sockfd,buffer,256);
return 0;
}
Here is the qt code
#include <Qt>
#include <QApplication>
#include <QTcpServer>
#include <QMessageBox>
#include <QTcpSocket>
#include <QtNetwork>
#include "qtserver.h"
Server::Server()
{
tcp = new QTcpServer(this);
tcp->listen(QHostAddress::Any,9876);
QObject::connect(tcp,SIGNAL(newConnection()),this,SLOT(printline()));
}
void Server::printline()
{
QTcpSocket *client = tcp->nextPendingConnection();
QObject::connect(client,SIGNAL(disconnected()),
client,SLOT(deleteLater()));
QDataStream in(client);
in.setVersion(QDataStream::Qt_4_0);
QString data;
in >> data;
printf("String = %s\n",(char*)data.data());
}
int main(int argc,char** argv)
{
QApplication a(argc,argv);
Server* server = new Server();
return a.exec();
}
When i try to run both of them I just get "String = " instead of the string outputting. Any idea what I'm doing wrong?
QString::data() returns QChar*, you can't just cast it to char* and hope that it would always work. For debugging QString, use qPrintable instead.
Also, QTcpSocket is very easy to use. Still, instead of writing the code from scratch, why not start by checkout out the examples, e.g. Fortune Server example.