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Is it possible to use select for packet sockets? I mean whether its necessary for the socket to be connection-based in order to use select function on it properly?
I'm seeing that the behavior of a socket which I got it by the following socket function call:
int socket_fd = socket(PF_PACKET, SOCK_RAW, htons(ETH_P_ALL));
is not as I expect. For example, I see that a ping packet which is 60 bytes long when received and read into a 20 bytes length buffer, it waits about a second between each recv function call. I used recvfrom and it didn't help. For this, I ask whether it's correct to use select for a packet socket?
Update
I'm going to include the code to discuss about it:
int MakeBridge(const char *if1, const char *if2)
{
int sock[2];
sock[0] = OpenSocket(if1);
sock[1] = OpenSocket(if2);
int activity;
char buf[20];
const int numSocks = 2;
int nfds = sock[0];
for (int i = 1; i < numSocks; i++)
if (sock[i] > nfds)
nfds = sock[i];
nfds++;
while (true)
{
FD_ZERO(&readfds);
for (int i = 0; i < numSocks; i++)
FD_SET(sock[i], &readfds);
activity = select(nfds, &readfds, NULL, NULL, NULL);
if (activity == -1) // sockets closed
break;
for (int i = 0; i < numSocks; i++)
if (FD_ISSET(_sock[i], &readfds))
{
int len;
CHECK(ioctl(_sock[i], FIONREAD, &len) != -1, "%s", strerror(errno));
printf("socket %d is set\n", i);
printf("total bytes available to read: %d\n", len);
CHECK(len > 0, "");
do
{
int n = min(len, sizeof(buf));
int nbr = recvfrom(_sock[i], buf, n, 0, NULL, NULL);
printf("n %d nbr %d\n", n, nbr);
CHECK(n == nbr, "");
len -= n;
} while (len);
}
}
return 0;
}
Update 2
Not going to segment messages and using large enough buffer makes the code as follows:
// This is a program which is going to make the bridge between two interfaces. brctl is going to be replaced by this program.
#define Uses_CHECK
#define Uses_close
#define Uses_errno
#define Uses_ETH_P_ALL
#define Uses_FD_SET
#define Uses_htons
#define Uses_ifreq
#define Uses_ioctl
#define Uses_printf
#define Uses_signal
#define Uses_sockaddr_ll
#define Uses_socket
#define Uses_strerror
#include <general.dep>
int _sock[2];
int _CtrlCHandler()
{
printf(" terminating...\n");
CHECK(close(_sock[0]) != -1, "");
CHECK(close(_sock[1]) != -1, "");
printf("all sockets closed successfully.\n");
}
void CtrlCHandler(int dummy)
{
_CtrlCHandler();
}
int OpenSocket(const char *ifname)
{
// getting socket
int socket_fd = socket(PF_PACKET, SOCK_RAW/*|SOCK_NONBLOCK*/, htons(ETH_P_ALL));
CHECK(socket_fd != -1, "%s", strerror(errno));
// init interface options struct with the interface name
struct ifreq if_options;
memset(&if_options, 0, sizeof(struct ifreq));
strncpy(if_options.ifr_name, ifname, sizeof(if_options.ifr_name) - 1);
if_options.ifr_name[sizeof(if_options.ifr_name) - 1] = 0;
// enable promiscuous mode
CHECK(ioctl(socket_fd, SIOCGIFFLAGS, &if_options) != -1, "%s", strerror(errno));
if_options.ifr_flags |= IFF_PROMISC;
CHECK(ioctl(socket_fd, SIOCSIFFLAGS, &if_options) != -1, "%s", strerror(errno));
// get interface index
CHECK(ioctl(socket_fd, SIOCGIFINDEX, &if_options) != -1, "%s", strerror(errno));
// bind socket to the interface
struct sockaddr_ll my_addr;
memset(&my_addr, 0, sizeof(my_addr));
my_addr.sll_family = AF_PACKET;
my_addr.sll_ifindex = if_options.ifr_ifindex;
CHECK(bind(socket_fd, (struct sockaddr *)&my_addr, sizeof(my_addr)) != -1, "%s", strerror(errno));
// socket is ready
return socket_fd;
}
int MakeBridge(const char *if1, const char *if2)
{
_sock[0] = OpenSocket(if1);
CHECK_NO_MSG(_sock[0]);
_sock[1] = OpenSocket(if2);
CHECK_NO_MSG(_sock[1]);
printf("sockets %d and %d opened successfully\n", _sock[0], _sock[1]);
fd_set readfds, orig;
int activity;
char buf[1<<16];
signal(SIGINT, CtrlCHandler);
int packetNumber = 0;
const int numSocks = _countof(_sock);
int nfds = _sock[0];
for (int i = 1; i < numSocks; i++)
if (_sock[i] > nfds)
nfds = _sock[i];
nfds++;
FD_ZERO(&orig);
for (int i = 0; i < numSocks; i++)
FD_SET(_sock[i], &orig);
while (true)
{
readfds = orig;
activity = select(nfds, &readfds, NULL, NULL, NULL);
if (activity == -1) // sockets closed
break;
CHECK(activity > 0, "");
for (int i = 0; i < numSocks; i++)
if (FD_ISSET(_sock[i], &readfds))
{
int len = recvfrom(_sock[i], buf, sizeof(buf), MSG_TRUNC, NULL, NULL);
CHECK(len > 0, "");
CHECK(len <= sizeof(buf), "small size buffer");
printf("%10d %d %d\n", ++packetNumber, i, len);
CHECK(sendto(_sock[!i], buf, len, 0, NULL, 0) == len, "");
}
}
return 0;
}
int Usage(int argc, const char *argv[])
{
printf("Usage: %s <if1> <if2>\n", argv[0]);
printf("Bridges two interfaces with the names specified.\n");
return 0;
}
int main(int argc, const char *argv[])
{
if (argc != 3)
return Usage(argc, argv);
CHECK_NO_MSG(MakeBridge(argv[1], argv[2]));
return 0;
}
I try to read the name of a file using scanf but failed.
I am very bad at pointers and could not find the problem.
Is there a problem with the pointer to the array of string?
Here is my code:
int* Read_file(char* str[])
{
FILE* fp = fopen(str[1], "r");
if(fp == NULL)
{
printf("File cannot open\n");
return NULL;
}
int rows = 0;
while(!feof(fp))
{
if(fgetc(fp) == '\n')
{
rows ++;
}
}
rows ++;
int* keys = (int*)malloc(3 * rows * sizeof(int));
fseek(fp, 0L, 0);
while(!feof(fp))
{
for(int i = 0;i < rows;i ++)
{
for(int j = 0;j < 3;j ++)
{
fscanf(fp,"%d", &keys[(3 * i) + j]);
}
}
}
fclose(fp);
return keys;
}
int main()
{
char* str[20];
printf("Build_tree ");
scanf("%s",&str);
int* keys = Read_file(str);
return 0;
}
Okay, so the thing is:
You need a char array to store a string(file-name). So you should use a char array. Instead, you were using an array of char pointers.
An array is actually a series of memory blocks. The name of the array represents a pointer to the first element of the array(in this case the first char variable).
While reading a string, scanf needs a location to store it. So you need to give it the address of the first char variable of your char array, which is available in your char array itself. So you have to pass str only to scanf. In the case of normal int,float, and such fundamental data types, their names represent memory blocks and not pointers to memory blocks, and hence you had to use a &.
Then for fopen, fopen expects a char*(which points to the first character of the char array stoing the filename) and you have to provide it with a char* . So you should pass str.
I think your code should go like
int* Read_file(char str[])
{
FILE* fp = fopen(str, "r");
if(fp == NULL)
{
printf("File cannot open\n");
return NULL;
}
int rows = 0;
while(!feof(fp))
{
if(fgetc(fp) == '\n')
{
rows ++;
}
}
rows ++;
int* keys = (int*)malloc(3 * rows * sizeof(int));
fseek(fp, 0L, 0);
while(!feof(fp))
{
for(int i = 0;i < rows;i ++)
{
for(int j = 0;j < 3;j ++)
{
fscanf(fp,"%d", &keys[(3 * i) + j]);
}
}
}
fclose(fp);
return keys;
}
int main()
{
char str[20];
printf("Build_tree ");
scanf("%s",str);
int* keys = Read_file(str);
//Whatever you want to do with the keys
return 0;
}
Comment for any queries.
I am struggling with this code. It's about counting some patterns from a text file. I tried to use thread(divide and conquer) processing, but it return a wrong value. I used mutex value to synchronize critical section.. The code is below. First main argument is number of threads, second is the name of a text file I want counting patterns from, and following patterns I want to look up on the text.
please save me..
Code is below
char *buffer;
int fsize, count;
char **searchword;
int *wordcount;
int *strlength;
typedef struct _params{
int num1;
int num2;
}params;
pthread_mutex_t mutex;
void *childfunc(void *arg)
{
int size, i, j, k, t, start, end, len, flag = -1;
int result;
params *a = (params *)arg;
start = a->num1;
end = a->num2;
while(1){
if(start == 0 || start == fsize)
break;
if(buffer[start]!= ' ' && buffer[start] != '\n' && buffer[start] != '\t')
start++;
else
break;
}
while(1){
if(end == fsize)
break;
if(buffer[end] != ' ' && buffer[end] != '\n' && buffer[end] != '\t')
end++;
else
break;
}
for(i = 0; i < count; i++){
len = strlength[i];
for(j = start; j<(end - len + 1); j++){
if(buffer[j] == searchword[i][0]){
flag = 0;
for(k = j +1; k<j + len; k++){
if(buffer[k] != searchword[i][k-j])
{
flag = 1;
break;
}
}
if(flag == 0){
pthread_mutex_lock(&mutex);
wordcount[i]++;
pthread_mutex_unlock(&mutex);// mutex unlocking
sleep(1);
flag = -1;
}
}
}
}
}
int main(int argc, char **argv){
FILE *fp;
char *inputFile;
pthread_t *tid;
int *status;
int inputNumber, i, j, diff, searchstart, searchend;
int result = 0;
count = argc -3;
inputNumber = atoi(argv[1]);
inputFile = argv[2];
searchword = (char **)malloc(sizeof(char *)*count);
tid = malloc(sizeof(pthread_t)*inputNumber);
strlength = (int *)malloc(4*count);
status = (int *)malloc(4*inputNumber);
wordcount = (int *)malloc(4*count);
for(i = 0; i < count; i++)
searchword[i] = (char*)malloc(sizeof(char)*(strlen(argv[i+3]) + 1));
for(i = 3; i < argc; i++)
strcpy(searchword[i-3], argv[i]);
fp = fopen(inputFile, "r");
fseek(fp, 0, SEEK_END);
fsize = ftell(fp);
rewind(fp);
buffer = (char *)malloc(1*fsize);
fread(buffer, fsize, 1, fp);
diff = fsize / inputNumber;
if(diff == 0)
diff = 1;
for(i = 0; i < count ; i++){
strlength[i] = strlen(searchword[i]);
wordcount[i] = 0;
}
for(i = 0; i < inputNumber; i++){
searchstart = 0 + i*diff;
searchend = searchstart + diff;
if(searchstart > fsize)
searchstart = fsize;
if(searchend > fsize)
searchend = fsize;
if( i == inputNumber -1)
searchend = fsize;
params a;
a.num1 = searchstart;
a.num2 = searchend;
pthread_mutex_init(&mutex, NULL);
result = pthread_create(&tid[i], NULL, childfunc, (void *)&a);
if(result < 0){
perror("pthread_create()");
}
}
//스레드 받는 부분
for(i = 0; i < inputNumber; i++){
result = pthread_join(tid[i], (void **)status);
if(result < 0)
perror("pthread_join()");
}
pthread_mutex_destroy(&mutex); // mutex 해제
for(i = 0; i < count; i++)
printf("%s : %d \n", searchword[i], wordcount[i]);
for(i = 0; i < count; i++) //동적메모리해제
free(searchword[i]);
free(searchword);
free(buffer);
free(tid);
free(strlength);
free(wordcount);
free(status);
fclose(fp);
return 0;
}
params a; // new a for each loop, previous a no longer exists
a.num1 = searchstart;
a.num2 = searchend;
pthread_mutex_init(&mutex, NULL);
result = pthread_create(&tid[i], NULL, childfunc, (void *)&a);
if(result < 0){
perror("pthread_create()");
}
} // a goes out of scope here
You pass each thread the address of a, but then a goes out of scope immediately after you create the thread. So the thread now has the address of some random leftover junk on the stack.
You need to have some conception of ownership of any object that's accessed by more than one thread like a is here. It can be owned by the thread that called pthread_create, owned by the newly-created thread, or jointly owned. But you have to be consistent. You have neither of these, why?
Is a owned only be the thread that called pthread_create? No, because the newly-created thread has a pointer to it and accesses it through that pointer. So the thread that called pthread_create cannot destroy it.
Is a owned only be the thread created by pthread_create? No, because it's on the stack of the thread that called pthread_create and will cease to exist when the next loop comes around.
Is a jointly owned? Well, no, because the thread that called pthread_create can destroy the object before the newly-created thread accesses it.
So no sane model of multi-thread use is followed by a. It's broken.
One common solution to this problem is to allocate a new structure (using malloc or new) for each thread, fill it in, and pass the thread the address of the structure. Let the thread free (or delete) the structure when it's done with it.
so... context: I'm doing a layer 2 protocol for flexible forwarding in vehicular environment (for now my testbed is in virtual machines), this should take in consideration a different number of interfaces (for multihoming) and multihop.
So what I have:
A way of broadcasting hop-by-hop the service provider.
What I'm triyng to do:
A way to register a session all the way from the client to the provider (And here is the problem)
Problem: I have two types of packets
1st is listened correctly and data payload starts with a 1
2nd for some reason is not detected but I can see the packet is sent and correct with tcpdump
Since I have to register in the application the interface where the connection is made I used select() which seems to be part of the problem since I only guessed how it was used and I'm kind of in the dark about this.
UPDATED v3:
Okay so as soon as I removed most of the stuff about only sending on a specific interface all the stuff worked perfectly (I still need to clean this code... it's kind of messy). Here is code if someone is interested:
#define __STDC_FORMAT_MACROS
#include <inttypes.h>
#include <time.h>
#include <stdlib.h>
#include <stdio.h>
#include <stdint.h>
#include <string.h>
#include <ifaddrs.h>
#include <signal.h>
#include <unistd.h>
#include <errno.h>
#include <arpa/inet.h>
#include <linux/if_packet.h>
#include <net/ethernet.h>
#include <sys/socket.h>
#include <sys/ioctl.h>
#include <net/if.h>
#include <netinet/in.h>
#define ETH_P_CUSTOM 0x0801 /* EtherType of Current Used Protocol*/
#define BUF_SIZE 1024
typedef enum {
false, true
} Bool; /* Boolean Definition*/
typedef struct Stat {
uint8_t maxSocket; /*Number of sockets to use in receive*/
uint8_t nInterfaces; /*Number of interfaces owned by this machine*/
uint8_t nSession; /*Number of Sessions Known in the linked list*/
uint8_t upMac[ETH_ALEN]; /*MAC of this host upstream parent*/
uint8_t nHops; /*Hops to Provider*/
char ifName[IF_NAMESIZE + 1]; /*Interface to Provider*/
} Stat;
typedef struct Node {
uint64_t session; /*Client Session*/
uint8_t nextHop[ETH_ALEN]; /*Next-Hop to Client*/
char ifName[IF_NAMESIZE + 1]; /*Outgoing Interface that connects to Next-Hop*/
struct Node * next; /*Next Session*/
} Node;
typedef struct ifNode {
uint8_t ifIndex; /*Interface index*/
uint8_t sock; /*Index in array of sockets*/
uint8_t mac[ETH_ALEN]; /*Interface MAC*/
char ifName[IF_NAMESIZE + 1]; /*Interface Name*/
struct ifNode * next; /*Next Session*/
} ifNode;
Stat * op; /* Variable which tracks status of certain structures/variables*/
Node * first = NULL, *last = NULL; /* Edges of linked list */
ifNode * iffirst = NULL, *iflast = NULL; /* Edges of interface linked list */
int cargc;
char **cargv;
int receiveP();
int broadServ();
int announceSelf();
Node* create(uint64_t sess, uint8_t n[ETH_ALEN], char interface[IF_NAMESIZE]);
void insert_node(Node * p);
Node* search(uint64_t session);
void update(uint64_t session, Node * p);
ifNode* createif(uint8_t idx, uint8_t sock, uint8_t ifmac[ETH_ALEN],
char interface[IF_NAMESIZE]);
void insert_ifnode(ifNode * p);
ifNode* searchif(uint8_t idx, uint8_t mode);
void updateif(uint8_t idx, ifNode * p);
void display();
void displayif();
void ctrlcoverride(int sig) {
printf("\nCtrl-C - Signal Caught - Exiting\n\n");
printf(
"Current Upstream MAC: %02x:%02x:%02x:%02x:%02x:%02x - NHops : %u - At Interface %s\n\n",
op->upMac[0], op->upMac[1], op->upMac[2], op->upMac[3],
op->upMac[4], op->upMac[5], op->nHops, op->ifName);
display();
exit(EXIT_SUCCESS);
}
Node* create(uint64_t sess, uint8_t n[ETH_ALEN], char interface[IF_NAMESIZE]) {
Node * new = (Node *) malloc(sizeof(Node));
if (new == NULL) {
printf("Could not create new node\n");
return NULL;
} else {
strcpy(new->ifName, interface);
new->session = sess;
int i;
for (i = 0; i < ETH_ALEN; i++)
new->nextHop[i] = n[i];
new->next = NULL;
return new;
}
}
ifNode* createif(uint8_t idx, uint8_t sock, uint8_t ifmac[ETH_ALEN],
char interface[IF_NAMESIZE]) {
ifNode * new = (ifNode *) malloc(sizeof(ifNode));
if (new == NULL) {
printf("Could not create new interface node\n");
return NULL;
} else {
new->ifIndex = idx;
new->sock = sock;
strcpy(new->ifName, interface);
int i;
for (i = 0; i < ETH_ALEN; i++)
new->mac[i] = ifmac[i];
new->next = NULL;
return new;
}
}
void insert_node(Node * p) {
if (first == last && last == NULL) {
first = last = p;
first->next = NULL;
last->next = NULL;
} else {
last->next = p;
last = last->next;
last->next = NULL;
}
}
void insert_ifnode(ifNode * p) {
if (iffirst == iflast && iflast == NULL) {
iffirst = iflast = p;
iffirst->next = NULL;
iflast->next = NULL;
} else {
iflast->next = p;
iflast = iflast->next;
iflast->next = NULL;
}
}
Node* search(uint64_t session) {
if (first == last && last == NULL) {
return NULL;
} else {
Node * temp;
for (temp = first; temp != NULL; temp = temp->next) {
if (temp->session == session) {
return temp;
}
}
return NULL;
}
}
ifNode* searchif(uint8_t idx, uint8_t mode) {
if (iffirst == iflast && iflast == NULL) {
return NULL;
} else {
ifNode * temp;
for (temp = iffirst; temp != NULL; temp = temp->next) {
if (temp->ifIndex == idx && mode == 0) {
return temp;
} else if (temp->sock == idx && mode == 1) {
return temp;
}
}
return NULL;
}
}
void update(uint64_t session, Node * p) {
if (first == last && last == NULL) {
return;
} else {
Node * temp;
for (temp = first; temp != NULL; temp = temp->next) {
if (temp->session == session) {
strcpy(temp->ifName, p->ifName);
temp->next = p->next;
int i;
for (i = 0; i < ETH_ALEN; i++)
temp->nextHop[i] = p->nextHop[i];
return;
}
}
}
}
void updateif(uint8_t idx, ifNode * p) {
if (iffirst == iflast && iflast == NULL) {
return;
} else {
ifNode * temp;
for (temp = iffirst; temp != NULL; temp = temp->next) {
if (temp->ifIndex == idx) {
strcpy(temp->ifName, p->ifName);
temp->sock = p->sock;
temp->next = p->next;
int i;
for (i = 0; i < ETH_ALEN; i++)
temp->mac[i] = p->mac[i];
return;
}
}
}
}
void display() {
Node * temp = first;
while (temp != NULL) {
printf("Session %" PRIu64 " Through %s - NextHop at ", temp->session,
temp->ifName);
int i;
for (i = 0; i < ETH_ALEN; i++)
printf("%02x ", temp->nextHop[i]);
printf("\n");
temp = temp->next;
}
}
void displayif() {
ifNode * temp = iffirst;
while (temp != NULL) {
printf("Interface Index %u Socket Number %u - Name %s with MAC: ",
temp->ifIndex, temp->sock, temp->ifName);
int i;
for (i = 0; i < ETH_ALEN; i++)
printf("%02x ", temp->mac[i]);
printf("\n");
temp = temp->next;
}
}
uint8_t counter() {
Node * temp = first;
uint8_t counter = 0;
while (temp != NULL) {
counter++;
temp = temp->next;
}
return counter;
}
fd_set rfds;
int rec;
int main(int argc, char **argv) {
setbuf(stdout, NULL);
signal(SIGINT, ctrlcoverride);
cargc = argc;
cargv = argv;
/*Setting Base Variables to Initial Values*/
op = (Stat*) malloc(sizeof(Stat));
op->nSession = 0;
memset(op->ifName, 0, IF_NAMESIZE);
op->maxSocket = 0;
op->nHops = UINT8_MAX - 1;
int i;
for (i = 0; i < ETH_ALEN; i++) {
op->upMac[i] = 0x00;
}
memset(&rfds, 0, sizeof(fd_set));
FD_ZERO(&rfds);
if (argc != 2) {
printf("USAGE: sudo %s {provider|node|nodekey}\n", cargv[0]);
exit(EXIT_FAILURE);
} else if (!(strcmp(cargv[1], "provider") == 0
|| strcmp(cargv[1], "node") == 0 || strcmp(cargv[1], "nodekey") == 0)) {
printf("USAGE: sudo %s {provider|node|nodekey}\n", cargv[0]);
exit(EXIT_FAILURE);
}
if (strcmp(cargv[1], "nodekey") == 0) {
srand(time(NULL));
uint8_t myArray[6] = { 0x00, 0x00, 0x00, 0x00, 0x00, 0x00 };
insert_node(
create((uint64_t) (100 * ((float) rand() / RAND_MAX)), myArray,
"SOURCE"));
}
struct ifaddrs *ifaddr, *ifa;
if (getifaddrs(&ifaddr) == -1) {
perror("getifaddrs");
exit(EXIT_FAILURE);
}
for (ifa = ifaddr, op->nInterfaces = 0; ifa != NULL; ifa = ifa->ifa_next) {
if (ifa->ifa_addr == NULL)
continue;
if (ifa->ifa_addr->sa_family == AF_PACKET
&& strncmp(ifa->ifa_name, "lo", strlen("lo")) != 0
&& strncmp(ifa->ifa_name, "tap", strlen("tap")) != 0) {
op->nInterfaces++;
}
}
rec = socket(AF_PACKET, SOCK_RAW, htons(ETH_P_CUSTOM));
int sockopt;
char ifName[IFNAMSIZ];
struct ifreq ifr;
for (i = 1, ifa = ifaddr; ifa != NULL;
ifa = ifa->ifa_next, i++) {
if (ifa->ifa_addr == NULL)
continue;
if (ifa->ifa_addr->sa_family == AF_PACKET
&& strncmp(ifa->ifa_name, "lo", strlen("lo")) != 0
&& strncmp(ifa->ifa_name, "tap", strlen("tap")) != 0) {
uint8_t sock;
if ((sock = socket(AF_PACKET, SOCK_RAW, htons(ETH_P_CUSTOM)))
== -1) {
printf("socket() error: %u - %s\n", errno, strerror(errno));
return EXIT_FAILURE;
}
if (setsockopt(sock, SOL_SOCKET, SO_REUSEADDR, &sockopt,
sizeof sockopt) == -1) {
printf("SO_REUSEADDR error: %u - %s\n", errno, strerror(errno));
close(sock);
return EXIT_FAILURE;
}
memset(&ifr, 0, sizeof(struct ifreq));
ifr.ifr_ifindex = i;
strcpy(ifr.ifr_name, ifa->ifa_name);
if (setsockopt(sock, SOL_SOCKET, SO_BINDTODEVICE, ifa->ifa_name,
IF_NAMESIZE) == -1) {
printf("SO_BINDTODEVICE error: %u - %s\n", errno,
strerror(errno));
close(sock);
return EXIT_FAILURE;
}
struct sockaddr_ll sll;
sll.sll_family = AF_PACKET;
sll.sll_ifindex = i;
sll.sll_protocol = htons(ETH_P_CUSTOM);
if ((bind(sock, (struct sockaddr *) &sll, sizeof(sll))) == -1) {
perror("Error binding raw socket to interface\n");
exit(-1);
}
if ((ioctl(sock, SIOCGIFHWADDR, &ifr)) != 0) {
printf("SIOCGIFHWADDR error: %u - %s\n", errno,
strerror(errno));
return EXIT_FAILURE;
}
int j;
uint8_t ifmac[ETH_ALEN];
for (j = 0; j < ETH_ALEN; j++) {
ifmac[j] = (uint8_t) (ifr.ifr_hwaddr.sa_data)[j];
}
FD_SET(sock, &rfds);
op->maxSocket = (op->maxSocket < sock) ? sock : op->maxSocket;
insert_ifnode(createif(i, sock, ifmac, ifr.ifr_name));
}
}
displayif();
if (strcmp(cargv[1], "provider") == 0) {
struct ifreq if_mac; // interface
char * interface = "eth1";
int sockfd;
if ((sockfd = socket(AF_PACKET, SOCK_RAW, htons(ETH_P_CUSTOM))) == -1) {
printf("socket() error: %u - %s\n", errno, strerror(errno));
return EXIT_FAILURE;
}
memset(&if_mac, 0, sizeof(struct ifreq));
strncpy(if_mac.ifr_name, interface, IFNAMSIZ - 1);
if ((ioctl(sockfd, SIOCGIFHWADDR, &if_mac)) != 0) {
printf("SIOCGIFHWADDR error: %u - %s\n", errno, strerror(errno));
return EXIT_FAILURE;
}
int i;
for (i = 0; i < ETH_ALEN; i++)
op->upMac[i] = ((uint8_t *) &if_mac.ifr_hwaddr.sa_data)[i];
op->nHops = 0;
close(sockfd);
}
freeifaddrs(ifaddr);
int stat = 0;
while (1) {
if (strcmp(cargv[1], "provider") == 0) {
if ((stat = receiveP()) != 0)
return stat;
if ((stat = broadServ()) != 0)
return stat;
display();
usleep(100000);
} else if (strcmp(cargv[1], "node") == 0
|| strcmp(cargv[1], "nodekey") == 0) {
if ((stat = receiveP()) != 0)
return stat;
if ((stat = announceSelf()) != 0){
return stat;
}
if ((stat = broadServ()) != 0)
return stat;
display();
usleep(100000);
}
}
ifNode * temp = iffirst;
while (temp != NULL) {
close(temp->sock);
temp = temp->next;
}
exit(stat);
}
int receiveP() {
int stat = 0;
struct ifreq ifr;
struct sockaddr saddr;
long unsigned int numbytes = 0;
char buf[BUF_SIZE];
memset(buf, 0, BUF_SIZE);
struct ether_header *eh = (struct ether_header *) buf;
unsigned int saddr_size = sizeof saddr;
struct timeval tv;
tv.tv_sec = 3; /* 3 Secs Timeout */
tv.tv_usec = 0;
setsockopt(rec, SOL_SOCKET, SO_RCVTIMEO, (char *) &tv,
sizeof(struct timeval));
numbytes = recvfrom(rec, buf, BUF_SIZE, 0, &saddr, &saddr_size);
int len;
int ntable;
switch (buf[sizeof(struct ether_header)]) {
case 1:
if (buf[sizeof(struct ether_header) + 1] < op->nHops) {
op->upMac[0] = eh->ether_shost[0];
op->upMac[1] = eh->ether_shost[1];
op->upMac[2] = eh->ether_shost[2];
op->upMac[3] = eh->ether_shost[3];
op->upMac[4] = eh->ether_shost[4];
op->upMac[5] = eh->ether_shost[5];
op->nHops = buf[sizeof(struct ether_header) + 1] + 1;
memset(&ifr, 0, sizeof(struct ifreq));
memset(&ifr.ifr_name, 0, IF_NAMESIZE);
printf(
"Server %u Hops Away - Through %02x:%02x:%02x:%02x:%02x:%02x At Interface %s\n",
op->nHops, eh->ether_shost[0], eh->ether_shost[1],
eh->ether_shost[2], eh->ether_shost[3], eh->ether_shost[4],
eh->ether_shost[5], op->ifName);
printf("\n\n");
}
break;
case 2:
len = sizeof(struct ether_header) + 1;
ntable = buf[len++];
int j;
for (j = 0; j < ntable; j++, len++) {
if (search(buf[len]) == NULL) {
insert_node(create(buf[len], eh->ether_shost, ""));
}
}
break;
}
return stat;
}
int broadServ() {
int stat = 0;
int tx_len = 0;
char sendbuf[BUF_SIZE];
char ifName[IF_NAMESIZE - 1];
struct ether_header *eh = (struct ether_header *) sendbuf;
struct sockaddr_ll socket_address;
int i;
struct ifreq ifr, if_mac;
ifNode * temp = iffirst;
while (temp != NULL) {
/* Get the index of the interface to send on */
memset(&ifr, 0, sizeof(struct ifreq));
ifr.ifr_ifindex = temp->ifIndex;
if (ioctl(temp->sock, SIOCGIFNAME, &ifr) < 0)
perror("SIOCGIFINDEX");
memset(ifName, 0, IF_NAMESIZE - 1);
strncpy(ifName, ifr.ifr_name, IF_NAMESIZE - 1);
/* Get the MAC address of the interface to send on */
memset(&if_mac, 0, sizeof(struct ifreq));
strncpy(if_mac.ifr_name, ifName, IFNAMSIZ - 1);
if (ioctl(temp->sock, SIOCGIFHWADDR, &if_mac) < 0)
perror("SIOCGIFHWADDR");
if (((uint8_t *) &if_mac.ifr_hwaddr.sa_data)[0] == 0x00
&& ((uint8_t *) &if_mac.ifr_hwaddr.sa_data)[1] == 0x00
&& ((uint8_t *) &if_mac.ifr_hwaddr.sa_data)[2] == 0x00
&& ((uint8_t *) &if_mac.ifr_hwaddr.sa_data)[3] == 0x00
&& ((uint8_t *) &if_mac.ifr_hwaddr.sa_data)[4] == 0x00
&& ((uint8_t *) &if_mac.ifr_hwaddr.sa_data)[5] == 0x00)
continue;
memset(sendbuf, 0, BUF_SIZE);
/* Ethernet header */
eh->ether_shost[0] = ((uint8_t *) &if_mac.ifr_hwaddr.sa_data)[0];
eh->ether_shost[1] = ((uint8_t *) &if_mac.ifr_hwaddr.sa_data)[1];
eh->ether_shost[2] = ((uint8_t *) &if_mac.ifr_hwaddr.sa_data)[2];
eh->ether_shost[3] = ((uint8_t *) &if_mac.ifr_hwaddr.sa_data)[3];
eh->ether_shost[4] = ((uint8_t *) &if_mac.ifr_hwaddr.sa_data)[4];
eh->ether_shost[5] = ((uint8_t *) &if_mac.ifr_hwaddr.sa_data)[5];
eh->ether_dhost[0] = 0xff;
eh->ether_dhost[1] = 0xff;
eh->ether_dhost[2] = 0xff;
eh->ether_dhost[3] = 0xff;
eh->ether_dhost[4] = 0xff;
eh->ether_dhost[5] = 0xff;
/* Ethertype field */
eh->ether_type = htons(ETH_P_CUSTOM);
tx_len = sizeof(struct ether_header);
/* Packet data */
sendbuf[tx_len++] = 1;
sendbuf[tx_len++] = op->nHops; //+1;
/* Index of the network device */
socket_address.sll_ifindex = temp->ifIndex;
/* Address length*/
socket_address.sll_halen = ETH_ALEN;
/* Destination MAC */
socket_address.sll_addr[0] = 0xff;
socket_address.sll_addr[1] = 0xff;
socket_address.sll_addr[2] = 0xff;
socket_address.sll_addr[3] = 0xff;
socket_address.sll_addr[4] = 0xff;
socket_address.sll_addr[5] = 0xff;
/* Send packet */
if (sendto(temp->sock, sendbuf, tx_len, 0,
(struct sockaddr*) &socket_address, sizeof(struct sockaddr_ll))
< 0)
printf("Send failed\n");
temp = temp->next;
}
return stat;
}
int announceSelf() {
if (op->upMac[0] == 0x00 && op->upMac[1] == 0x00 && op->upMac[2] == 0x00
&& op->upMac[3] == 0x00 && op->upMac[4] == 0x00
&& op->upMac[5] == 0x00)
return EXIT_SUCCESS;
int stat = 0;
int tx_len = 0;
char sendbuf[BUF_SIZE];
char ifName[IF_NAMESIZE - 1];
struct ether_header *eh = (struct ether_header *) sendbuf;
struct sockaddr_ll socket_address;
int i;
struct ifreq ifr, if_mac;
ifNode * temp = iffirst;
while (temp != NULL) {
memset(&ifr, 0, sizeof(struct ifreq));
ifr.ifr_ifindex = temp->ifIndex;
if (ioctl(temp->sock, SIOCGIFNAME, &ifr) < 0)
perror("SIOCGIFINDEX");
memset(ifName, 0, IF_NAMESIZE - 1);
strncpy(ifName, ifr.ifr_name, IF_NAMESIZE - 1);
/* Get the MAC address of the interface to send on */
memset(&if_mac, 0, sizeof(struct ifreq));
strncpy(if_mac.ifr_name, ifName, IFNAMSIZ - 1);
if (ioctl(temp->sock, SIOCGIFHWADDR, &if_mac) < 0)
perror("SIOCGIFHWADDR");
if (((uint8_t *) &if_mac.ifr_hwaddr.sa_data)[0] == 0x00
&& ((uint8_t *) &if_mac.ifr_hwaddr.sa_data)[1] == 0x00
&& ((uint8_t *) &if_mac.ifr_hwaddr.sa_data)[2] == 0x00
&& ((uint8_t *) &if_mac.ifr_hwaddr.sa_data)[3] == 0x00
&& ((uint8_t *) &if_mac.ifr_hwaddr.sa_data)[4] == 0x00
&& ((uint8_t *) &if_mac.ifr_hwaddr.sa_data)[5] == 0x00)
continue;
memset(sendbuf, 0, BUF_SIZE);
/* Ethernet header */
eh->ether_shost[0] = ((uint8_t *) &if_mac.ifr_hwaddr.sa_data)[0];
eh->ether_shost[1] = ((uint8_t *) &if_mac.ifr_hwaddr.sa_data)[1];
eh->ether_shost[2] = ((uint8_t *) &if_mac.ifr_hwaddr.sa_data)[2];
eh->ether_shost[3] = ((uint8_t *) &if_mac.ifr_hwaddr.sa_data)[3];
eh->ether_shost[4] = ((uint8_t *) &if_mac.ifr_hwaddr.sa_data)[4];
eh->ether_shost[5] = ((uint8_t *) &if_mac.ifr_hwaddr.sa_data)[5];
eh->ether_dhost[0] = op->upMac[0];
eh->ether_dhost[1] = op->upMac[1];
eh->ether_dhost[2] = op->upMac[2];
eh->ether_dhost[3] = op->upMac[3];
eh->ether_dhost[4] = op->upMac[4];
eh->ether_dhost[5] = op->upMac[5];
/* Ethertype field */
eh->ether_type = htons(ETH_P_CUSTOM);
tx_len = sizeof(struct ether_header);
/* Packet data */
sendbuf[tx_len++] = 2;
sendbuf[tx_len++] = counter();
Node *temp1 = first;
for (; temp1 != NULL; temp1 = temp1->next) {
sendbuf[tx_len++] = temp1->session;
}
socket_address.sll_ifindex = temp->ifIndex;
/* Address length*/
socket_address.sll_halen = ETH_ALEN;
/* Destination MAC */
socket_address.sll_addr[0] = op->upMac[0];
socket_address.sll_addr[1] = op->upMac[1];
socket_address.sll_addr[2] = op->upMac[2];
socket_address.sll_addr[3] = op->upMac[3];
socket_address.sll_addr[4] = op->upMac[4];
socket_address.sll_addr[5] = op->upMac[5];
/* Send packet */
if (sendto(temp->sock, sendbuf, tx_len, 0,
(struct sockaddr*) &socket_address, sizeof(struct sockaddr_ll))
< 0)
printf("Send failed\n");
temp = temp->next;
}
return stat;
}
So to test this you can have VM with linux connected like this (for example):
Provider ----- Node ----- Node ----- Nodekey
I still had a problem when creating multiple sessions, i wasn't incrementing the buffer when reading and I was reading multiple times the same position. Now it's working good
OK, let's begin with the easiest recommendations but I'm not sure this is going to resolve the problem at once. I did a system like this many years ago for different boards with different processor architectures communicating with each other. All the boards were running within a telecommunication switch. It's a very nice problem and you are facing it in the proper way with a peer-to-peer distributed solution.
I didn't go through all code but it seems each node is discovering the neighbour nodes in the network and everyone is creating a tree.
In select, the first argument should not be FD_SETSIZE but the highest-numbered file descriptor in any of the three sets (in this case the read set), plus 1.
The infinite loop is calling receiveSession which is creating all sockets again and then it reads. If a frame with your specific layer-2 protocol arrives in the middle and there is no socket listening for it, it will be discarded. Maybe your problem could be here.
When you send Ethernet frames directly, the hardware will complete the frame to the minimum Ethernet size: 64 octets (so you might receive padding data up to 46 octets - Octets not Bytes)
Please read here:
http://en.wikipedia.org/wiki/Ethernet_frame
It is good you chose an EtherType ETH_P_CUSTOM higher than 1536 that is not already in use but maybe you want to use a much higher number in order to minimize possibilities of collision with other protocols.
Something important. Your testbed now is with VM's which are usually x86 architectures, 64 bits. When you run your software in real devices with different processors, that might not be the situation. This is very important because you might have different architectures with different endianship and different integer size. That will affect the integer numbers you send, especially in ether_header, and the size of your structures. You have to use the the macros ntohs, ntohl, htons, htonl to change between host and network endianship (session is uint64_t). You should send data in network endianship. This is not solving your very current problem but you might have this problem in the future.
I would like to have a dns-parser. I have found this code:
https://github.com/uvic-sdo/DNS-Packet-Parser
Which is quite useful and understandable. It prints DNS answer (Resource Records) using RR structure:
typedef struct {
uint16_t type;
uint16_t clas;
uint32_t ttl;
uint16_t rdlength;
} static_RR;
The answer is than derived from packet:
static_RR* RRd = (static_RR*) ((void*) pd->data + sizeofUrl(pd->data));
I have two questions:
1) How to get a name of the dns answer?
2) How can I derive a dns query. By creating a separate structure, perhaps?
rfc1035: 4.1.3. Resource record format
code example rfc1035: DNS client
typedef __declare_packed_struct s_dns_rr
{
uint16_t name;
uint16_t type;
uint16_t class;
int32_t ttl;
uint16_t rdlength;
} s_dns_rr;
int
parse_rr(uint8_t *res, uint8_t **offset)
{
s_dns_rr *rr;
uint16_t rdlength = 0;
size_t qname_len = 0;
uint8_t qname[DNS_QNAME_MAX_LEN] = {0};
rr = (s_dns_rr *) *offset;
if (DNS_PTR_NAME == dns_ptr_type(rr->name))
{
parse_label(res, res + dns_ptr_offset(rr->name), qname, &qname_len);
}
rdlength = ntohs(rr->rdlength);
*offset += sizeof(*rr);
fprintf(stdout, " -> %s %s %s %u %u", qname,
tr_dns_str(dns_type_str, rr->type, uint16_t, ntohs),
tr_dns_str(dns_class_str, rr->class, uint16_t, ntohs),
ntohl(rr->ttl), rdlength);
if (0 == rdlength)
{
fprintf(stdout, "\n");
return 0;
}
fprintf(stdout, " ");
switch (ntohs(rr->type))
{
case DNS_TYPE_CNAME:
qname_len = 0;
qname[0] = 0;
parse_label(res, (uint8_t *) &rr->name, qname, &qname_len);
if (qname_len == 0)
{
qname[0] = 0;
}
fprintf(stdout, "%s", (const char *) qname);
break;
case DNS_TYPE_A:
fprintf(stdout, "%u.%u.%u.%u", (*offset)[0], (*offset)[1], (*offset)[2],
(*offset)[3]);
break;
default:
break;
}
fprintf(stdout, "\n");
*offset += rdlength;
return (int) rdlength;
}