How to listen to IGMPv3 frames - c

I need to get IGMPv3 Frames for this I'm using a socket like following:
sockfd = socket(AF_INET, SOCK_RAW, IPPROTO_IGMP);
the problem is that my program is filtring IGMPv3 Frames, i don't know why !! I don't get IGMP frames although I'm getting them when using wireshark. I tried also to use :
sockfd = socket(PF_PACKET, SOCK_RAW, htons(0x0800));
but I was capable of getting only ICMP frames and not IGMP ones.
PS: I tried my program on another machine and it worked, so I think the problem is with my kernel, does anyone know if there is any configuration to do with the socket ?
Here is the whole code:
#include <arpa/inet.h>
#include <linux/if_packet.h>
#include <linux/ip.h>
#include <linux/udp.h>
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <sys/ioctl.h>
#include <sys/socket.h>
#include <net/if.h>
#include <netinet/ether.h>
#include <unistd.h>
#define DEST_MAC0 0x01
#define DEST_MAC1 0x00
#define DEST_MAC2 0x5e
#define DEST_MAC3 0x00
#define DEST_MAC4 0x00
#define DEST_MAC5 0x16
#define ETHER_TYPE 0x0800
#define DEFAULT_IF "eth1"
#define BUF_SIZ 1024
int main(int argc, char *argv[])
{
char sender[INET6_ADDRSTRLEN];
int sockfd, ret, i, counter;
int sockopt;
ssize_t numbytes;
struct ifreq ifopts; /* set promiscuous mode */
struct ifreq if_ip; /* get ip addr */
struct sockaddr_storage their_addr;
uint8_t buf[BUF_SIZ];
char ifName[IFNAMSIZ];
/* Get interface name */
if (argc > 1)
strcpy(ifName, argv[1]);
else
strcpy(ifName, DEFAULT_IF);
/* Header structures */
struct ether_header *eh = (struct ether_header *) buf;
struct iphdr *iph = (struct iphdr *) (buf + sizeof(struct ether_header));
struct udphdr *udph = (struct udphdr *) (buf + sizeof(struct iphdr) + sizeof(struct ether_header));
memset(&if_ip, 0, sizeof(struct ifreq));
/* Open PF_PACKET socket, listening for EtherType ETHER_TYPE */
// if ((sockfd = socket(PF_PACKET, SOCK_RAW, htons(ETHER_TYPE))) == -1) {
// perror("listener: socket");
// return -1;
// }
sockfd = socket(PF_PACKET, SOCK_RAW, htons(ETHER_TYPE));
if (sockfd == -1) {
perror("listener: socket");
return -1;
}
/* Set interface to promiscuous mode - do we need to do this every time? */
strncpy(ifopts.ifr_name, ifName, IFNAMSIZ-1);
ioctl(sockfd, SIOCGIFFLAGS, &ifopts);
ifopts.ifr_flags |= IFF_PROMISC;
ioctl(sockfd, SIOCSIFFLAGS, &ifopts);
/* Allow the socket to be reused - incase connection is closed prematurely */
if (setsockopt(sockfd, SOL_SOCKET, SO_REUSEADDR, &sockopt, sizeof sockopt) == -1) {
perror("setsockopt");
close(sockfd);
exit(EXIT_FAILURE);
}
/* Bind to device */
if (setsockopt(sockfd, SOL_SOCKET, SO_BINDTODEVICE, ifName, IFNAMSIZ-1) == -1) {
perror("SO_BINDTODEVICE");
close(sockfd);
exit(EXIT_FAILURE);
}
repeat: printf("listener: Waiting to recvfrom...\n");
numbytes = recvfrom(sockfd, buf, BUF_SIZ, 0, NULL, NULL);
printf("listener: got packet %lu bytes\n Frame = {",(unsigned long int) numbytes);
for( counter = 0; counter < numbytes; counter++)
printf( "%02X ", buf[counter]);
printf( "}");
/* Check the packet is for me */
if (eh->ether_dhost[0] == DEST_MAC0 &&
eh->ether_dhost[1] == DEST_MAC1 &&
eh->ether_dhost[2] == DEST_MAC2 &&
eh->ether_dhost[3] == DEST_MAC3 &&
eh->ether_dhost[4] == DEST_MAC4 &&
eh->ether_dhost[5] == DEST_MAC5) {
printf("Correct destination MAC address\n");
} else {
printf("Wrong destination MAC: %x:%x:%x:%x:%x:%x\n",
eh->ether_dhost[0],
eh->ether_dhost[1],
eh->ether_dhost[2],
eh->ether_dhost[3],
eh->ether_dhost[4],
eh->ether_dhost[5]);
ret = -1;
goto done;
}
/* Get source IP */
((struct sockaddr_in *)&their_addr)->sin_addr.s_addr = iph->saddr;
inet_ntop(AF_INET, &((struct sockaddr_in*)&their_addr)->sin_addr, sender, sizeof sender);
/* Look up my device IP addr if possible */
strncpy(if_ip.ifr_name, ifName, IFNAMSIZ-1);
if (ioctl(sockfd, SIOCGIFADDR, &if_ip) >= 0) { /* if we can't check then don't */
printf("Source IP: %s\n My IP: %s\n", sender,
inet_ntoa(((struct sockaddr_in *)&if_ip.ifr_addr)->sin_addr));
/* ignore if I sent it */
if (strcmp(sender, inet_ntoa(((struct sockaddr_in *)&if_ip.ifr_addr)->sin_addr)) == 0) {
printf("but I sent it :(\n");
ret = -1;
goto done;
}
}
/* UDP payload length */
ret = ntohs(udph->len) - sizeof(struct udphdr);
/* Print packet */
printf("\tData:");
for (i=0; i<numbytes; i++) printf("%02x:", buf[i]);
printf("\n");
done: goto repeat;
close(sockfd);
return ret;
}
Please note that the address mac that I'm initializing is the address that I get from IGMP frame on wireshark. this code actually allows me to detect only ICMP frames.
When using:
sockfd = socket(AF_INET, SOCK_RAW, IPPROTO_IGMP);
instead of:
sockfd = socket(PF_PACKET, SOCK_RAW, htons(ETHER_TYPE);
I don't get nothing !
On wireshark I'm getting all the frames that I want including IGMP and ICMP!!

Related

UDP Sockets - One server, mulitple clients. Not sent to all clients

I am writing in windows, using Visual Studio, and am trying to have one application use UDP sockets to broadcast a message to other applications. This must be done with UDP sockets.
It works well with just one client, but it does not when I add another client, and all listen on the same port.
TX (Server)
/* Example from: http://matrixsust.blogspot.com/2011/10/udp-server-client-in-c.html */
/* Use legacy sockets */
#define _WINSOCK_DEPRECATED_NO_WARNINGS
/* Add a linker to ws2_32.lib, the Winsock2 library */
#pragma comment(lib, "ws2_32.lib")
#include <stdio.h>
#include <winsock2.h>
int main()
{
WSADATA wsaData;
int sock, sin_size;
struct sockaddr_in server_addr;
struct hostent* host;
char send_data[1024];
boolean keep_running = 1;
unsigned int cmd_no_block_arg = 1;
int SERVER_PORT;
/* Obtain a valid port */
printf("Enter a port number to connect to (i.e. 7171):\n");
scanf_s("%d", &SERVER_PORT);
if ((SERVER_PORT < 1) || (SERVER_PORT > 665534))
{
SERVER_PORT = 7171;
}
/* Initialize Winsock version 2.2 */
WSAStartup(MAKEWORD(2, 2), &wsaData);
/* CLIENT SIDE */
host = (struct hostent*) gethostbyname((char*)"127.0.0.1");
if ((sock = socket(AF_INET, SOCK_DGRAM, IPPROTO_UDP)) == -1)
{
perror("socket");
exit(1);
}
/* SETUP */
server_addr.sin_family = AF_INET;
server_addr.sin_port = htons(SERVER_PORT);
server_addr.sin_addr = *((struct in_addr*)host->h_addr);
memset(server_addr.sin_zero, 0, sizeof(server_addr.sin_zero));
sin_size = sizeof(struct sockaddr);
/* Bind the socket, then enable non-blocking semantics */
if ((ioctlsocket(sock, FIONBIO, &cmd_no_block_arg) == SOCKET_ERROR))
{
printf("Could not non-bind socket. Error Code %i\n", WSAGetLastError());
}
while (keep_running)
{
printf("Type Something (q or Q to quit):");
gets_s(send_data, sizeof(send_data));
if ((strcmp(send_data, "q") == 0) || strcmp(send_data, "Q") == 0)
{
keep_running = 0;
}
else
{
sendto(sock, send_data, strlen(send_data), 0, (struct sockaddr*) & server_addr, sizeof(struct sockaddr));
}
} // While
}
RX (Clients)
/* Example from: http://matrixsust.blogspot.com/2011/10/udp-server-client-in-c.html */
#define _WINSOCK_DEPRECATED_NO_WARNINGS
/* Add a linker to ws2_32.lib, the Winsock2 library */
#pragma comment(lib, "ws2_32.lib")
#include <stdio.h>
#include <winsock2.h>
#include <sys/types.h>
#include <stdio.h>
#include <errno.h>
#include <string.h>
#include <stdlib.h>
int main()
{
WSADATA wsaData;
int sock;
int addr_len, bytes_read;
char recv_data[1024], send_data[1024];
struct sockaddr_in server_addr, client_addr;
int sharing_flag = 1; /* Allow sharing */
unsigned int non_block_flag = 1;
unsigned int SERVER_PORT = 7171;
/* Obtain a valid port to connect to */
printf("Enter a port number to connect to (i.e. 7171):\n");
scanf_s("%d", &SERVER_PORT);
if ((SERVER_PORT < 1) || (SERVER_PORT > 65535))
{
SERVER_PORT = 7171;
}
/* Initialize Winsock version 2.2 */
WSAStartup(MAKEWORD(2, 2), &wsaData);
/* SERVER SIDE: bind(), recvfrom(), sendto() */
if ((sock = socket(AF_INET, SOCK_DGRAM, IPPROTO_UDP)) == -1) {
perror("Socket");
exit(1);
}
server_addr.sin_family = AF_INET;
server_addr.sin_port = htons(SERVER_PORT);
server_addr.sin_addr.s_addr = INADDR_ANY;
memset(server_addr.sin_zero, 0, sizeof(server_addr.sin_zero));
/* Eliminates "ERROR on binding: Address already in use" error */
if (setsockopt(sock, SOL_SOCKET, SO_REUSEADDR, (void*)&sharing_flag, sizeof(sharing_flag)) == SOCKET_ERROR)
{
printf("Error on socket opt: %i\n", WSAGetLastError());
}
if ((bind(sock, (struct sockaddr*) & server_addr, sizeof(struct sockaddr)) == SOCKET_ERROR) ||
(ioctlsocket(sock, FIONBIO, &non_block_flag) == SOCKET_ERROR))
{
printf("Error on socket bind: %i\n", WSAGetLastError());
}
addr_len = sizeof(struct sockaddr);
printf("\nUDPServer Waiting for client on port %i\n", SERVER_PORT);
while (1)
{
bytes_read = recvfrom(sock, recv_data, 1024, 0, (struct sockaddr*) & client_addr, &addr_len);
if (bytes_read >= 0)
{
recv_data[bytes_read] = '\0';
printf("\n(%s , %d) said : ", inet_ntoa(client_addr.sin_addr), ntohs(client_addr.sin_port));
printf("%s\n", recv_data);
fflush(stdout);
} /* if we read in bytes */
} /* while */
return 0;
}

SocketCAN read from socket only returns 11cobid

I am trying to read from a socketCAN and the msg is always filtered for the 11bit identifier.
This should be a problem fixable with setting the rpoper flags for the 29bit identifier but I can`t find where if anyone can help...
struct can_frame message;
struct sockaddr_can addr;
struct ifreq ifr;
int fd = -1; // file descriptor (it´s a socket)
if((fd = socket(PF_CAN, SOCK_RAW, CAN_RAW)) < 0)
{
LE_INFO("cannot open socket");
return;
}
strcpy(ifr.ifr_name, "can0");
ioctl(fd, SIOCGIFINDEX, &ifr);
addr.can_family = AF_CAN;
addr.can_ifindex = ifr.ifr_ifindex;
if(bind(fd, (struct sockaddr *)&addr, sizeof(addr)) < 0)
{
printf("cannot bind socket\n");
return;
}
uint8_t nbytes;
message.can_id |= CAN_EFF_FLAG;
while(1)
{
nbytes = read(fd, &message, sizeof(struct can_frame));
if (nbytes < 0) {
perror("can raw socket read");
return;
}
/* paranoid check ... */
if (nbytes < sizeof(struct can_frame)) {
fprintf(stderr, "read: incomplete CAN frame\n");
return;
}
printf("READ COB_ID:%x\n",message.can_id | CAN_EFF_FLAG);
}
return;
I am sending a CAN frame with idx x901 and this is what is printed:
READ COB_ID:80000101
READ COB_ID:80000101
READ COB_ID:80000101
I have troubleshooted this in many different ways and it seems that the C code is working as it should, but I suspect the problem to be with the kernel module for either mcp251x which is not correctly receiving the extended flag? Or it may be with some initialization I need to do before running the kernel module???
Thank you in advance to anyone who can help.
Your understanding of CAN flags and filtering is not correct. Take a look at extract from linux can.h:
/* special address description flags for the CAN_ID */
#define CAN_EFF_FLAG 0x80000000U /* EFF/SFF is set in the MSB */
#define CAN_RTR_FLAG 0x40000000U /* remote transmission request */
#define CAN_ERR_FLAG 0x20000000U /* error message frame */
/* valid bits in CAN ID for frame formats */
#define CAN_SFF_MASK 0x000007FFU /* standard frame format (SFF) */
#define CAN_EFF_MASK 0x1FFFFFFFU /* extended frame format (EFF) */
#define CAN_ERR_MASK 0x1FFFFFFFU /* omit EFF, RTR, ERR flags */
Here is an example that works for both SFF and EFF messages:
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <net/if.h>
#include <sys/ioctl.h>
#include <sys/socket.h>
#include <linux/can.h>
#include <linux/can/raw.h>
int main(int argc, char **argv)
{
struct can_frame message;
struct sockaddr_can addr;
struct ifreq ifr;
int fd = -1; // file descriptor (it´s a socket)
if((fd = socket(PF_CAN, SOCK_RAW, CAN_RAW)) < 0)
{
printf("cannot open socket");
return -9;
}
strcpy(ifr.ifr_name, "vcan0");
ioctl(fd, SIOCGIFINDEX, &ifr);
addr.can_family = AF_CAN;
addr.can_ifindex = ifr.ifr_ifindex;
if(bind(fd, (struct sockaddr *)&addr, sizeof(addr)) < 0)
{
printf("cannot bind socket\n");
return -1;
}
u_int8_t nbytes;
message.can_id |= CAN_EFF_FLAG | CAN_RTR_FLAG | CAN_EFF_MASK;
while(1)
{
nbytes = read(fd, &message, sizeof(struct can_frame));
if (nbytes < 0) {
perror("can raw socket read");
return -2;
}
/* paranoid check ... */
if (nbytes < sizeof(struct can_frame)) {
fprintf(stderr, "read: incomplete CAN frame\n");
return -3;
}
printf("READ COB_ID: %x\n", message.can_id & CAN_EFF_MASK);
}
return 0;
}
Now sending these messages:
cansend vcan0 00000123#FFFFFFFFFFFFFFFF
cansend vcan0 12345678#FFFFFFFFFFFFFFFF
gives correct output:
READ COB_ID: 123
READ COB_ID: 12345678

Multicasting in C: Binary does not receive when using addrinfo

I have this funny little problem in two nearly identical programs. What I am trying to do is send some data on Multicast socket and receive it. For now, I am okay if the sender receives the message (I'll set the option to not receive later).
I have two implementation cases. In the first approach, I am using the traditional way of initializing a sockaddr structure and then binding to, and also joining a multicast group on the same socket. This, however, is IPv4/IPv6 dependent and to circumvent that, I tried to use addrinfo structures in the second variant of the program. Both programs are given below.
The problem is, the messages are being received in the first use case, where I am using the regular sockaddr while, there is no message being received/socket descriptor being set in the second case. Could somebody help me out and explain why is this happening?
Variant 1 (with sockaddr)
#include<stdio.h>
#include <stdlib.h>
#include <sys/socket.h>
#include <stdio.h>
#include <string.h>
#include <arpa/inet.h>
#include <netinet/in.h>
#include <sys/param.h>
#include <unistd.h>
#include <errno.h>
#include <time.h>
#include <fcntl.h> /* for nonblocking */
#include <netinet/tcp.h>
fd_set hm_tprt_conn_set;
main()
{
struct ip_mreq mreq;
struct sockaddr_in mc_addr;
int sock_fd ;
int val;
int reuse = 1;
struct sockaddr_in ip;
struct sockaddr_in src_addr;
int total_bytes_rcvd=0;
unsigned int length;
unsigned char buf[50];
int op_complete = 0;
int os_error;
struct timeval select_timeout;
fd_set read_set;
int32_t nready; //Number of ready descriptors
time_t time_val;
length = sizeof (src_addr);
sock_fd = socket(AF_INET, SOCK_DGRAM,0);
if(sock_fd == -1)
{
printf("\n Error Opening UDP MCAST socket");
perror("\n Cause is ");
exit(0);
}
printf("\n Setting the socket to non-blocking mode");
val = fcntl(sock_fd, F_GETFL , 0);
val = fcntl(sock_fd, F_SETFL, val | O_NONBLOCK);
if (val == -1)
{
printf("\n Error while setting socket to non-blocking mode");
perror("Cause is ");
sock_fd = -1;
exit(0);
} //end if val == -1
if (setsockopt(sock_fd,SOL_SOCKET,SO_REUSEADDR, &reuse, sizeof(reuse)) == -1)
{
fprintf(stderr, "setsockopt: %d\n", errno);
perror("Cause is ");
exit(0);
}
FD_SET(sock_fd, &hm_tprt_conn_set);
printf("\n Construct a mcast address structure");
/* construct a multicast address structure */
memset(&mc_addr, 0, sizeof(mc_addr));
mc_addr.sin_family = AF_INET;
mc_addr.sin_addr.s_addr = htonl(INADDR_ANY);
mc_addr.sin_port = htons(4936);
memset(&ip, 0, sizeof(ip));
ip.sin_family = AF_INET;
ip.sin_addr.s_addr = inet_addr("224.0.0.203")/*htonl(INADDR_ANY)*/;
ip.sin_port = htons(4936);
printf("\n Bind the multicast address structure and port to the recieving socket ");
if (bind( sock_fd, (struct sockaddr*) &mc_addr, sizeof(mc_addr)) == -1)
{
fprintf(stderr, "bind: %d\n", errno);
perror("\n Cause is ");
exit(0);
}
mreq.imr_multiaddr.s_addr = inet_addr("224.0.0.203");
mreq.imr_interface.s_addr = htonl(INADDR_ANY);
if(setsockopt(sock_fd, IPPROTO_IP, IP_ADD_MEMBERSHIP,&mreq, sizeof(mreq)) == -1)
{
fprintf(stderr, "setsockopt: %d\n", errno);
perror("\n Cause is ");
exit(0);
}
printf("\nCreated Recv Socket: %d", sock_fd);
fflush(stdout);
memset(&src_addr, 0, sizeof(mc_addr));
while(1){
/* Send a multicast */
time_val = time(NULL);
snprintf(buf, sizeof(buf), "Hello: %s", ctime(&time_val));
total_bytes_rcvd = sendto(sock_fd,
buf,
sizeof(buf),
0,
(struct sockaddr *)&ip,
length );
printf("\n%d bytes sent.", total_bytes_rcvd);
/* perform select */
select_timeout.tv_sec = 0;
select_timeout.tv_usec = 5000000;
read_set = hm_tprt_conn_set;
nready = select(sock_fd+1, &read_set, NULL, NULL, &select_timeout);
if(nready == 0)
{
/***************************************************************************/
/* No descriptors are ready */
/***************************************************************************/
continue;
}
else if(nready == -1)
{
perror("Error Occurred on select() call.");
continue;
}
if(FD_ISSET(sock_fd, &read_set))
{
printf("\n Recv the data");
total_bytes_rcvd = recvfrom(sock_fd,
buf,
sizeof(buf),
0,
(struct sockaddr *)&src_addr,
&length );
printf("%s: message = \" %s \"\n", inet_ntoa(src_addr.sin_addr), buf);
printf("\n total byte recieved %d", total_bytes_rcvd);
/***************************************************************************/
/* If select returned 1, and it was a listen socket, it makes sense to poll*/
/* again by breaking out and use select again. */
/***************************************************************************/
if(--nready <=0)
{
printf("\nNo more incoming requests.");
continue;
}
}//end select on listenfd
}
}
Variant 2 (with addrinfo)
#include<stdio.h>
#include <stdlib.h>
#include <sys/socket.h>
#include <stdio.h>
#include <string.h>
#include <arpa/inet.h>
#include <netinet/in.h>
#include <sys/param.h>
#include <unistd.h>
#include <errno.h>
#include <time.h>
#include <fcntl.h> /* for nonblocking */
#include <netinet/tcp.h>
#include <netdb.h> /* AI_PASSIVE and other Macros for getaddrinfo() */
fd_set hm_tprt_conn_set;
main()
{
struct addrinfo hints, *res, *ressave;
char target[128] = "127.0.0.1";
char service[128] = "4936";
struct ip_mreq mreq;
int sock_fd ;
int val;
int reuse = 1;
struct sockaddr_in ip;
struct sockaddr_in src_addr;
int total_bytes_rcvd=0;
unsigned int length;
unsigned char buf[50];
int op_complete = 0;
int os_error;
struct timeval select_timeout;
fd_set read_set;
int32_t nready; //Number of ready descriptors
time_t time_val;
length = sizeof (src_addr);
sock_fd = socket(AF_INET, SOCK_DGRAM,0);
if(sock_fd == -1)
{
printf("\n Error Opening UDP MCAST socket");
perror("\n Cause is ");
exit(0);
}
printf("\n Setting the socket to non-blocking mode");
val = fcntl(sock_fd, F_GETFL , 0);
val = fcntl(sock_fd, F_SETFL, val | O_NONBLOCK);
if (val == -1)
{
printf("\n Error while setting socket to non-blocking mode");
perror("Cause is ");
sock_fd = -1;
exit(0);
} //end if val == -1
if (setsockopt(sock_fd,SOL_SOCKET,SO_REUSEADDR, &reuse, sizeof(reuse)) == -1)
{
fprintf(stderr, "setsockopt: %d\n", errno);
perror("Cause is ");
exit(0);
}
FD_SET(sock_fd, &hm_tprt_conn_set);
printf("\n Construct a mcast address structure");
/* construct a multicast address structure */
hints.ai_family = AF_INET;
hints.ai_socktype = SOCK_DGRAM;
hints.ai_protocol = IPPROTO_UDP;
if((os_error = getaddrinfo(target, service, &hints, &res)) !=0)
{
printf("\n%s",gai_strerror(os_error));
exit(0);
}
ressave = res;
if(bind(sock_fd, res->ai_addr, res->ai_addrlen) != 0)
{
perror("Error binding to port");
close(sock_fd);
sock_fd = -1;
}
mreq.imr_multiaddr.s_addr = inet_addr("224.0.0.203");
mreq.imr_interface.s_addr = htonl(INADDR_ANY);
if(setsockopt(sock_fd, IPPROTO_IP, IP_ADD_MEMBERSHIP,&mreq, sizeof(mreq)) == -1)
{
fprintf(stderr, "setsockopt: %d\n", errno);
perror("Cause is ");
exit(0);
}
/* Set Destination address */
memset(&ip, 0, sizeof(ip));
ip.sin_family = AF_INET;
ip.sin_addr.s_addr = inet_addr("224.0.0.203")/*htonl(INADDR_ANY)*/;
ip.sin_port = htons(4936);
/* Set to zero address where addresses of sender will be received */
memset(&src_addr, 0, sizeof(src_addr));
while(1){
/* Send a multicast */
time_val = time(NULL);
snprintf(buf, sizeof(buf), "Hello: %s", ctime(&time_val));
total_bytes_rcvd = sendto(sock_fd,
buf,
sizeof(buf),
0,
(struct sockaddr *)&ip,
length );
printf("\n%d bytes sent.", total_bytes_rcvd);
/* perform select */
select_timeout.tv_sec = 0;
select_timeout.tv_usec = 5000000;
read_set = hm_tprt_conn_set;
nready = select(sock_fd+1, &read_set, NULL, NULL, &select_timeout);
if(nready == 0)
{
/***************************************************************************/
/* No descriptors are ready */
/***************************************************************************/
continue;
}
else if(nready == -1)
{
perror("Error Occurred on select() call.");
continue;
}
if(FD_ISSET(sock_fd, &read_set))
{
printf("\n Recv the data");
total_bytes_rcvd = recvfrom(sock_fd,
buf,
sizeof(buf),
0,
(struct sockaddr *)&src_addr,
&length );
printf("%s: message = \" %s \"\n", inet_ntoa(src_addr.sin_addr), buf);
printf("\n total byte recieved %d", total_bytes_rcvd);
/***************************************************************************/
/* If select returned 1, and it was a listen socket, it makes sense to poll*/
/* again by breaking out and use select again. */
/***************************************************************************/
if(--nready <=0)
{
printf("\nNo more incoming requests.");
continue;
}
}//end select on listenfd
}
}
The difference is that in the first variant you're binding to INADDR_ANY, while in the second variant you're binding to 127.0.0.1. Failing to bind to INADDR_ANY means you won't receive any multicast data.
You can fix this with the following:
hints.ai_family = AF_INET;
hints.ai_socktype = SOCK_DGRAM;
hints.ai_protocol = IPPROTO_UDP;
hints.ai_flags = AI_PASSIVE | AI_NUMERICSERV;
if((os_error = getaddrinfo(NULL, service, &hints, &res)) !=0)
{
printf("\n%s",gai_strerror(os_error));
exit(0);
}
From the man page for getaddrinfo regarding AI_PASSIVE:
If node is NULL, the network address in each socket structure is initialized according to the AI_PASSIVE flag, which is set in
hints.ai_flags. The network address in each socket structure will be
left unspecified if AI_PASSIVE flag is set. This is used by server
applications, which intend to accept client connections on any network
address. The network address will be set to the loopback interface
address if the AI_PASSIVE flag is not set. This is used by client
applications, which intend to connect to a server running on the same
network host.
While in this case you are sending to the same host, multicast data does not go out on the localhost interface by default. You would need to call setsockopt with the IP_MULTICAST_IF option to set the outgoing multicast interface.
With this change, I was able to send and receive with the second variant.
Before you can bind() you need to have a working socket. You will need to cycle through all the results. Here's what's missing on your code.
ressave = res;
sock = socket(ressave->ai_family, ressave->ai_socktype, ressave->ai_protocol);
while(ressave != NULL && (sock < 0 || connect(sock, ressave->ai_addr, ressave->ai_addrlen) < 0)) {
close(sock);
if((ressave = ressave->ai_next) != NULL)
sock = socket(ressave->ai_family, ressave->ai_socktype, ressave->ai_protocol);
}
At this point you have either found a working socket sock or not. When ressave is not NULL then the value of socket sock is valid.

Multicasting on Ubuntu

My situation is as follows:
I have a windows machine running a UDP Multicast server that is broadcasting packets. I wrote a window client that is able to capture these packets without a problem on a separate windows machine that is connected to the network. I ran into a few firewall problems on the windows machines, but worked that out.
Now, I have an ubuntu 12.04 version of the client; however, my program isn't finding these packets. I ran through all the suggestions provided by other stack overflow posts and some google threads:
when I am running my client, netstat -g shows the IP address of the multicast network
I set the rp_filter to 0 using sysctl
I can see the packets when using tcpdump -i wlan0
Added a route (sudo route add -net 224.0.0.0 netmask 224.0.0.0 wlan0)
For step four, this is a wireless connection established over wlan0, so I add the route on wlan0. Similarly, wlan0's rp_filter=0.
Now, for the code. From the print statements and error checking. I am seeing that I am successfully binding, joining the multicast group, creating the buffer, etc... Then it just blocks at the recvfrom() function call.
#include <sys/types.h>
#include <sys/socket.h>
#include <arpa/inet.h>
#include <netinet/in.h>
#include <netdb.h>
#include <stdio.h>
#include <stdlib.h>
#include <cstring>
#include <unistd.h>
#include <pthread.h>
#include <fstream>
#pragma warning( disable : 4996 )
#define MAX_PACKETSIZE 100000 // max size of packet (actual packet size is dynamic)
bool IPAddress_StringToAddr(char *szNameOrAddress, struct in_addr *Address);
void Unpack(char* pData);
#define MULTICAST_ADDRESS "239.255.42.99" // IANA, local network
#define PORT_COMMAND 1510
#define PORT_DATA 1511
#define SOCKET_ERROR -1
#define INVALID_SOCKET -1
typedef int SOCKET;
SOCKET DataSocket;
int main(int argc, char* argv[])
{
int retval;
char szMyIPAddress[128] = "";
in_addr MyAddress, MultiCastAddress;
int optval = 0x100000;
int optval_size = 4;
// client address
if(argc>1)
{
strcpy(szMyIPAddress, argv[1]); // specified on command line
IPAddress_StringToAddr(szMyIPAddress, &MyAddress);
}
else
{ printf("usage: ./client [local_ip_address]\n"); return 0; }
MultiCastAddress.s_addr = inet_addr(MULTICAST_ADDRESS);
printf("Client: %s\n", szMyIPAddress);
printf("Multicast Group: %s\n", MULTICAST_ADDRESS);
// create a "Data" socket
printf("Create Socket.\n");
DataSocket = socket(AF_INET, SOCK_DGRAM, 0);
// allow multiple clients on same machine to use address/port
int value = 1;
printf("Set SO_REUSEADDR sockopt.\n");
retval = setsockopt(DataSocket, SOL_SOCKET, SO_REUSEADDR, (char*)&value, sizeof(value));
if (retval == SOCKET_ERROR)
{
close(DataSocket);
return -1;
}
//bind
struct sockaddr_in MySocketAddr;
memset(&MySocketAddr, 0, sizeof(MySocketAddr));
MySocketAddr.sin_family = AF_INET;
MySocketAddr.sin_port = htons(PORT_DATA);
MySocketAddr.sin_addr = MyAddress;
printf("Bind Socket.\n");
if (bind(DataSocket, (struct sockaddr *)&MySocketAddr, sizeof(struct sockaddr)) == SOCKET_ERROR)
{
printf("[PacketClient] bind failed.\n");
return 0;
}
// join multicast group
struct ip_mreq Mreq;
Mreq.imr_multiaddr = MultiCastAddress;
Mreq.imr_interface = MyAddress;
printf("Join multicast group.\n");
retval = setsockopt(DataSocket, IPPROTO_IP, IP_ADD_MEMBERSHIP, (char *)&Mreq, sizeof(Mreq));
if (retval == SOCKET_ERROR)
{
printf("[PacketClient] join failed.\n");
return -1;
}
// create a 1MB buffer
printf("Create 1MB Buffer.\n");
setsockopt(DataSocket, SOL_SOCKET, SO_RCVBUF, (char *)&optval, 4);
getsockopt(DataSocket, SOL_SOCKET, SO_RCVBUF, (char *)&optval, (socklen_t*)&optval_size);
if (optval != 0x100000)
{
printf("[PacketClient] ReceiveBuffer size = %d\n", optval);
}
//listening
printf("Listening...\n");
char szData[20000];
int addr_len = sizeof(struct sockaddr);
sockaddr_in TheirAddress;
while (1)
{
// Block until we receive a datagram from the network (from anyone including ourselves)
int nDataBytesReceived = recvfrom(DataSocket, szData, sizeof(szData), 0, (sockaddr *)&TheirAddress, (socklen_t*)&addr_len);
Unpack(szData);
}
return 0;
}
// convert ipp address string to addr
bool IPAddress_StringToAddr(char *szNameOrAddress, struct in_addr *Address)
{
int retVal;
struct sockaddr_in saGNI;
char hostName[256];
char servInfo[256];
u_short port;
port = 0;
// Set up sockaddr_in structure which is passed to the getnameinfo function
saGNI.sin_family = AF_INET;
saGNI.sin_addr.s_addr = inet_addr(szNameOrAddress);
saGNI.sin_port = htons(port);
// getnameinfo
if ((retVal = getnameinfo((sockaddr *)&saGNI, sizeof(sockaddr), hostName, 256, servInfo, 256, NI_NUMERICSERV)) != 0)
{
printf("[PacketClient] GetHostByAddr failed.\n");
return false;
}
Address->s_addr = saGNI.sin_addr.s_addr;
return true;
}
void Unpack(char* pData)
{
printf("Begin Packet\n-------\n");
}
Any suggestions are appreciated. Here is the question I used as a reference when trying to fix this problem: UDP socket (multicast) not receiving data (Ubuntu)
I paste my answer here instead writing it in comments.
As I understood you have windows machines on both sides, successfully broadcasting udp packets and now you want to replace them with ubuntu machines. And the machines are receiving the packets, but your client isn't notified.
Maybe this will help
SOL_SOCKET is for the socket layer, IPPROTO_IP for the IP layer, etc... For multicast programming, level will always be IPPROTO_IP
Here is the working code for simplified RIPv2 protocol that sends and reives multicast traffic without an problem.
int setup_sender_connection(struct in_addr interface_addr){
//create socket
int sock = socket(AF_INET, SOCK_DGRAM, 0);
if(sock<0){
die("Creating Socket");
}
//set outgoing interface
if(setsockopt(sock, IPPROTO_IP, IP_MULTICAST_IF, &interface_addr, sizeof(interface_addr))<0){
die("Setting outgoing interface");
}
//disable loopback
u_char loop = 0;
if(setsockopt(sock, IPPROTO_IP, IP_MULTICAST_LOOP, &loop, sizeof(loop))<0){
die("Disabling loopback");
}
//allow reusing of port
int reuse = 1;
if(setsockopt(sock, SOL_SOCKET, SO_REUSEADDR, (char *)&reuse, sizeof(reuse)) < 0){
die("Allowing reuse");
}
//bind to this port
struct sockaddr_in saddr;
bzero(&saddr, sizeof(struct sockaddr_in));
saddr.sin_family = AF_INET;
saddr.sin_port = htons(520);
saddr.sin_addr = interface_addr;
if(bind(sock, (struct sockaddr *)&saddr, sizeof(struct sockaddr_in))<0){
die("Binding");
}
return sock;
}
void join_group(int sock, struct in_addr interface_addr){
//join gorup
struct ip_mreq mreq;
bzero(&mreq, sizeof(struct ip_mreq));
mreq.imr_multiaddr.s_addr = inet_addr(MULTICAST_IP); /* IP multicast address of group */
mreq.imr_interface = interface_addr; /* local IP address of interface */
if(setsockopt(sock, IPPROTO_IP, IP_ADD_MEMBERSHIP, &mreq, sizeof(mreq))<0){
die("Joining group");
}
}
void die(char *error){
perror(error);
exit(1);
}

Raw socket with device bind using setsockopt() system is not working in Fedora core 6(2.6.18-1.2798.fc6)

Please any one could help on this issue. Please
In the below sample code,we had bind raw sock with eth0. but while running the program
the recvfrom of raw sock is receiving packets from eth0 & eth1 on same machine(xx_86).
It is not clear to me why,could help one on this issue.
I hope the setsockopt is not working properly
OS: Fedora core 6(2.6.18-1.2798.fc6)
Sampe code:
#include <stdio.h>
#include <stdlib.h>
#include <errno.h>
#include <unistd.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <linux/if_ether.h>
#include <net/if.h>
#include <linux/filter.h>
#include <sys/ioctl.h>
#include <string.h>
#include <arpa/inet.h>
int main(int argc, char **argv) {
int sock, i;
unsigned char buffer[2048];
unsigned char tbuff[2048];
unsigned char *iphead, *ethhead,*phead;
struct ifreq ethreq;
// NOTE: use TCPDUMP to build the filter array.
// set filter to sniff only port 443
// $ sudo tcpdump -dd port 443
// raw for recvfrom eth0
if ((sock = socket(PF_PACKET, SOCK_RAW, htons(ETH_P_IP))) == -1) {
perror("socket");
exit(1);
}
// set network card to promiscuos
strncpy(ethreq.ifr_name, "eth0", IFNAMSIZ);
if (ioctl(sock,SIOCGIFFLAGS, &ethreq) == -1) {
perror("ioctl");
close(sock);
exit(1);
}
ethreq.ifr_flags |= IFF_PROMISC;
if (ioctl(sock, SIOCSIFFLAGS, &ethreq) == -1) {
perror("ioctl");
close(sock);
exit(1);
}
//bind to sock with eth0
struct ifreq Interface;
memset(&Interface, 0, sizeof(Interface));
strncpy(Interface.ifr_ifrn.ifrn_name, "eth0", IFNAMSIZ);
if (setsockopt(sock, SOL_SOCKET, SO_BINDTODEVICE, &Interface, sizeof(Interface)) < 0) { close(sock); }
//open the RAW socket for sendto
int s = socket (PF_INET, SOCK_RAW, IPPROTO_RAW);
struct sockaddr_in sin;
memset(&sin,0,sizeof(sin));
sin.sin_family = AF_INET;
sin.sin_port = htons(0);
sin.sin_addr.s_addr = inet_addr ("10.3.161.104");
// inform kernal don't fill IP and Transport header
int one = 1;
const int *val = &one;
if (setsockopt (s, IPPROTO_IP, IP_HDRINCL, val, sizeof (one)) < 0)
printf ("Warning: Cannot set HDRINCL!\n");
//bind the sock descriptor with eth0
struct ifreq Interface1;
memset(&Interface1, 0, sizeof(Interface1));
strncpy(Interface1.ifr_ifrn.ifrn_name, "eth0", IFNAMSIZ);
if (setsockopt(s, SOL_SOCKET, SO_BINDTODEVICE, &Interface1, sizeof(Interface1)) < 0) { close(s); }
while (1) {
printf("----------------------\n");
i = recvfrom(sock, buffer, sizeof(buffer), 0, NULL, NULL);
printf("%d bytes read\n", i);
// check header size: Ethernet = 14, IP = 20, TCP = 8 (sum = 42)
if (i < 42) {
perror("recvfrom():");
printf("Incomplete packet (errno is %d)\n", errno);
close(sock);
exit(0);
}
phead = buffer + 14; // (skip ethernet header)
memcpy(tbuff,phead,i-14);
iphead=tbuff;
if (*iphead == 0x45) {
int ptrindex= iphead[9];
switch(ptrindex){
case 1:
printf("The transport protocl is:ICMP\n");
break;
case 2:
printf("The transport protol is:IGMP\n");
break;
case 6:
printf("The transport protocol is:TCP\n");
break;
case 17:
printf("The transport protocol is:UDP\n");
break;
case 103:
printf("The transport protocol is:PIM\n");
break;
default:
printf("The transport protocol is:%d\n",iphead[9]);
}
//printf("%d",*ptrindex);
// printf("\n The transport protocol is :%u\n",iphead[9]);
printf("Source Address: %d.%d.%d.%d, Port: %d\n",
iphead[12], iphead[13], iphead[14], iphead[15], (iphead[20] << 8) + iphead[21]);
printf("Dest Address: %d.%d.%d.%d, Port: %d\n",
iphead[16], iphead[17], iphead[18], iphead[19], (iphead[22] << 8) + iphead[23]);
if(sendto(s,tbuff,i-14,0,(struct sockaddr *)&sin,sizeof(sin))<0)
printf("error\n");
else{printf("\nThe received packet is send\n");}
memset(buffer,0,sizeof(buffer));
memset(tbuff,0,sizeof(tbuff));
}
else{ printf("The non ip had received");}
}
close(sock);
}
In the linux man page (http://linux.die.net/man/7/socket) :
SO_BINDTODEVICE
Bind this socket to a particular device like "eth0", as specified in the passed interface name. If the name is an empty string or the option length is zero, the socket device binding is removed. The passed option is a variable-length null-terminated interface name string with the maximum size of IFNAMSIZ. If a socket is bound to an interface, only packets received from that particular interface are processed by the socket. Note that this only works for some socket types, particularly AF_INET sockets. It is not supported for packet sockets (use normal bind(2) there).
So, try the bind instead.
Thanks all,thanks you very much for valuable time. it is worked with bind approach
The code segments had helped me.
setsockopt() is bug in the fedora 2.6.18
alternative approach is below.
void BindToInterface(int raw , char *device , int protocol) {
struct sockaddr_ll sll;
struct ifreq ifr; bzero(&sll , sizeof(sll));
bzero(&ifr , sizeof(ifr));
strncpy((char *)ifr.ifr_name ,device , IFNAMSIZ);
//copy device name to ifr
if((ioctl(raw , SIOCGIFINDEX , &ifr)) == -1)
{
perror("Unable to find interface index");
exit(-1);
}
sll.sll_family = AF_PACKET;
sll.sll_ifindex = ifr.ifr_ifindex;
sll.sll_protocol = htons(protocol);
if((bind(raw , (struct sockaddr *)&sll , sizeof(sll))) ==-1)
{
perror("bind: ");
exit(-1);
}
return 0;
}

Resources