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This question has been asked many times, but searching through and implementing some solutions that have worked for others, I still haven't been able to figure out what I'm doing wrong. I am still having issues understanding programming with sockets, so any explanations would be greatly appreciated. The function where I am getting the error is "int forwardClientReq(char* buffer, char* hostname, int clientfd)" and more specifically around this:
numBytesSent = send(serverfd, buffer, strlen(buffer), 0);
if(numBytesSent == -1)
printf("Oh dear, something went wrong with send()! %s\n", strerror(errno));
The full code is as follows:
/* Proxy application called webproxy */
// Copy past http server includes, remove unnecessary
#include <stdio.h>
#include <stdlib.h>
#include <string.h> /* for fgets */
#include <strings.h> /* for bzero, bcopy */
#include <unistd.h> /* for read, write */
#include <sys/socket.h> /* for socket use */
#include <netdb.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <pthread.h>
#include <errno.h>
#define MAXBUF 8192 /* max text line length */
#define LISTENQ 1024 /* second argument to listen() */
#define ERRBUFSIZE 1024
#define HEAPBUF 32768 // 2^15
int open_listenfd(int port);
void webProxy(int connfd);
void *thread(void *vargp);
int connect2Client(char* ip, char* port);
void sendErrResponse(char* errBUF, int connfd);
int forwardClientReq(char* buffer, char* host, int clientfd);
int main(int argc, char **argv)
{
int timeout = 0;
/* Check if the function was called correctly */
/* Store arguments provided (port number & cache timeout) */
if(argc < 2 || argc > 3){
fprintf(stderr, "Incorrect arguments, Usage: ./<executableFile> <port#> <timeout(optional)>\n");
exit(0);
}
if(argc == 3)
timeout = atoi(argv[2]);
int listenfd, *connfdp, port, clientlen=sizeof(struct sockaddr_in);
pthread_t tid;
struct sockaddr_in clientaddr;
port = atoi(argv[1]); // store the port number
listenfd = open_listenfd(port); // create persistant TCP socket for client HTTP requests
/* Create,Bind,Listen SOCKET and multithread */
while (1) {
connfdp = malloc(sizeof(int)); // pointer to pass the socket
*connfdp = accept(listenfd, (struct sockaddr*)&clientaddr, &clientlen);
if(*connfdp<0)
printf("There is an error accepting the connection with the client");
pthread_create(&tid, NULL, thread, connfdp); // call thread function with tid
}
}
/* thread routine */
void * thread(void * vargp)
{
int connfd = *((int *)vargp);
pthread_detach(pthread_self());
free(vargp);
webProxy(connfd);
close(connfd);
return NULL;
}
void webProxy(int connfd)
{
size_t n;
char buffer[MAXBUF]; // pointer to pass the socket
char errorBuf[ERRBUFSIZE];
bzero(errorBuf, ERRBUFSIZE);
bzero(buffer, MAXBUF);
char httpmsg[]="HTTP/1.1 200 Document Follows\r\nContent-Type:text/html\r\nContent-Length:32\r\n\r\n<html><h1>Hello CSCI4273 Course!</h1>";
char hostname[50];
n = read(connfd, buffer, MAXBUF); // read the requst up to maxbuf sizeof
printf("server received the following request:\n%s\n",buffer);
/* parse the request */
char requestType[50], fullPath[50];
bzero(requestType, 50);
bzero(fullPath, 50);
sscanf(buffer, "%s %s", requestType, fullPath);
printf("requestType = %s, and fullPath= %s\n", requestType, fullPath);
/* I tried a million different methods and libary suggestions but this is the only
method that I found to easily parse the information I wanted to input */
// sscanf(fullPath, "http://www.%511[^/\n]", hostname);
sscanf(fullPath, "http://%511[^/\n]", hostname);
printf("hostname is = %s\n", hostname);
/* support only GET requests */
if(strcmp(requestType, "GET") != 0)
{
printf("Proxy received a request that was not a 'GET' Request, sending 400 Bad Request response\n");
sendErrResponse(errorBuf, connfd);
}
// // /* support only HTTP/1.1 */
// else if(strcmp(Type, "HTTP/1.1") != 0)
// {
// printf("Proxy received a request that was not an HTTP/1.1 version, sending 400 Bad Request response");
// // I think the error message below is 80, but I could be wrong. Need to double check or use strlen function
// sprintf(errorBuf, "HTTP/1.1 400 Bad Request\r\nContent-Type:text/html\r\nContent-Length: %d\r\n\r\n",80);
// write(connfd, errorBuf, strlen(errorBuf));
// bzero(errorBuf, ERRBUFSIZE);
// }
/* parse and verify the hostname/server */
struct hostent *host = gethostbyname(hostname);
if (host == NULL) {
fprintf(stderr,"ERROR, no such host as %s\n", hostname);
sendErrResponse(errorBuf, connfd);
exit(0);
}
else{
/* Forward request to HTTP server */
forwardClientReq(buffer, hostname, connfd);
printf("buffer = %s\n", buffer);
/* Relay data from server to client */
}
}
int forwardClientReq(char* buffer, char* hostname, int clientfd)
{
char* serverResponse = malloc(HEAPBUF); // create a buffer for receiving the response from the server
bzero(serverResponse, HEAPBUF); // zeroize the buffer
/* open a socket with the server */
struct sockaddr_in serveraddr;
int serverSock, optval =1;
/* Create a socket descriptor */
if(-1 == (serverSock = socket(AF_INET, SOCK_STREAM, 0))) // yoda condition...
{
printf("Error: Unable to create socket in 'open_listenfd' function");
return -1;
}
/* Eliminates "Address already in use" error from bind. */
if (setsockopt(serverSock, SOL_SOCKET, SO_REUSEADDR, &optval , sizeof(int)) < 0){
printf("Error in setsockopt in forwardClientReq function");
return -1;
}
struct hostent* host = gethostbyname(hostname);
serveraddr.sin_family = AF_INET;
memcpy(&serveraddr.sin_addr, host->h_addr_list[0], host->h_length);
serveraddr.sin_port = htons(80); //(you should pick the correct remote port or use the default 80 port if noneis specified).
socklen_t addrlen = sizeof(serveraddr); // The addrlen argument specifies the size of serveraddr.
int serverfd = connect(serverSock, (struct sockaddr*) &serveraddr, addrlen);
if(serverfd < 0)
printf("improper connection when trying to forward client's request/n");
/* send the client message to the server */
int numBytesSent = 0;
printf("buffer before send = %s\n", buffer);
sprintf(buffer, "\r\n\r\n");
numBytesSent = send(serverfd, buffer, strlen(buffer), 0);
if(numBytesSent == -1)
printf("Oh dear, something went wrong with send()! %s\n", strerror(errno));
// printf("Sent %d to the server", numBytesSent);
// /* store the server's response */
// int numBytesRead = 0;
// numBytesRead = read(serverfd, serverResponse, HEAPBUF);
// printf("Sent %d to the server", numBytesRead);
//
// /* send the response to the client. This is a moment here the proxy can cache the page,
// inspect the data, and do all kinds of cool proxy-level things */
// numBytesSent = write(clientfd, serverResponse, strlen(serverResponse));
// printf("Sent %d to the server", numBytesSent);
free(serverResponse); // free malloc'd space
}
int open_listenfd(int port)
{
int listenfd, optval=1;
struct sockaddr_in serveraddr;
/* Create a socket descriptor */
if ((listenfd = socket(AF_INET, SOCK_STREAM, 0)) < 0)
{
printf("Error: Unable to create socket in 'open_listenfd' function");
return -1;
}
/* Eliminates "Address already in use" error from bind. */
if (setsockopt(listenfd, SOL_SOCKET, SO_REUSEADDR, &optval , sizeof(int)) < 0)
return -1;
/* listenfd will be an endpoint for all requests to port
on any IP address for this host */
bzero((char *) &serveraddr, sizeof(serveraddr));
serveraddr.sin_family = AF_INET;
serveraddr.sin_addr.s_addr = htonl(INADDR_ANY);
serveraddr.sin_port = htons((unsigned short)port);
/* bind: associate the parent socket with a port */
if (bind(listenfd, (struct sockaddr*)&serveraddr, sizeof(serveraddr)) < 0)
return -1;
/* Make it a listening socket ready to accept connection requests */
if (listen(listenfd, LISTENQ) < 0)
return -1;
return listenfd;
} /* end open_listenfd */
void sendErrResponse(char* errorBuf, int connfd)
{
// I think the error message below is 80, but I could be wrong. Need to double check or use strlen function
sprintf(errorBuf, "HTTP/1.1 400 Bad Request\r\nContent-Type:text/html\r\nContent-Length: %d\r\n\r\n",80);
write(connfd, errorBuf, strlen(errorBuf));
bzero(errorBuf, ERRBUFSIZE);
}
The return value of connect is an error code not a socket fd:
If the connection or binding succeeds, zero is returned. On error,
-1 is returned, and errno is set appropriately.
So
numBytesSent = send(serverfd, buffer, strlen(buffer), 0);
Should be
numBytesSent = send(serverSock, buffer, strlen(buffer), 0);
I have written a code to create and set the properties of VLAN interface. I am able to set the IP address, however the I am facing problem in setting the gateway address and reading the device flags. Please have a look at code and suggest what could be wrong.
I am getting error in the function generic_ioctrlcall.
/**
* Create socket function
*/
int create_socket()
{
int sockfd = 0;
sockfd = socket(AF_INET, SOCK_DGRAM, 0);
if(sockfd == -1){
fprintf(stderr, "Could not get socket.\n");
return -1;
}
return sockfd;
}
/**
* Generic ioctrlcall to reduce code size
*/
int generic_ioctrlcall(int sockfd, u_long *flags, struct ifreq *ifr) {
if (ioctl(sockfd, (long unsigned int)flags, &ifr) < 0) {
fprintf(stderr, "ioctl: %s\n", (char *)flags);
return -1;
}
return 1;
}
/**
* Set route with metric 100
*/
int set_route(int sockfd, char *gateway_addr, struct sockaddr_in *addr) {
struct rtentry route;
int err = 0;
memset(&route, 0, sizeof(route));
addr = (struct sockaddr_in*) &route.rt_gateway;
addr->sin_family = AF_INET;
addr->sin_addr.s_addr = inet_addr(gateway_addr);
addr = (struct sockaddr_in*) &route.rt_dst;
addr->sin_family = AF_INET;
addr->sin_addr.s_addr = inet_addr("0.0.0.0");
addr = (struct sockaddr_in*) &route.rt_genmask;
addr->sin_family = AF_INET;
addr->sin_addr.s_addr = inet_addr("0.0.0.0");
route.rt_flags = RTF_UP | RTF_GATEWAY;
route.rt_metric = 100;
if ((err = ioctl(sockfd, SIOCADDRT, &route)) < 0) {
fprintf(stderr, "ioctl: %s\n", (char *)flags);
return -1;
}
return 1;
}
/**
* Set ip function
*/
int set_ip(char *iface_name, char *ip_addr, char *gateway_addr)
{
if(!iface_name)
return -1;
struct ifreq ifr;
struct sockaddr_in sin;
int sockfd = create_socket();
sin.sin_family = AF_INET;
// Convert IP from numbers and dots to binary notation
inet_aton(ip_addr,&sin.sin_addr.s_addr);
/* get interface name */
strncpy(ifr.ifr_name, iface_name, IFNAMSIZ);
/* Read interface flags */
generic_ioctrlcall(sockfd, (u_long *)"SIOCGIFFLAGS", &ifr);
/*
* Expected in <net/if.h> according to
* "UNIX Network Programming".
*/
#ifdef ifr_flags
# define IRFFLAGS ifr_flags
#else /* Present on kFreeBSD */
# define IRFFLAGS ifr_flagshigh
#endif
// If interface is down, bring it up
if (ifr.IRFFLAGS | ~(IFF_UP)) {
ifr.IRFFLAGS |= IFF_UP;
generic_ioctrlcall(sockfd, (u_long *)"SIOCSIFFLAGS", &ifr);
}
// Set route
set_route(sockfd, gateway_addr, &sin);
memcpy(&ifr.ifr_addr, &sin, sizeof(struct sockaddr));
// Set interface address
if (ioctl(sockfd, SIOCSIFADDR, &ifr) < 0) {
fprintf(stderr, "Cannot set IP address. ");
perror(ifr.ifr_name);
return -1;
}
#undef IRFFLAGS
return 0;
}
Many problems here. The proximate cause of your difficulty is that the second argument to ioctl is a long integer, not a pointer to a character string.
generic_ioctrlcall(sockfd, (u_long *)"SIOCGIFFLAGS", &ifr);
does not create a pointer to the integer value of SIOCGIFFLAGS which is presumably what you intended. Other issues:
(1) Since ioctl takes a long integer as the second argument, why did you want to pass a pointer to an integer? Just pass the integer as argument.
(2) If you do wish to pass a pointer to an integer, you would need to do something like this:
u_long ioctl_arg = SIOCGIFFLAGS;
generic_ioctrlcall(sockfd, &ioctl_arg, &ifr);
(3) You cannot convert a pointed-to integer to an integer simply by casting it. You need to dereference the pointer. That is:
Change:
if (ioctl(sockfd, (long unsigned int)flags, &ifr) < 0) {
to:
if (ioctl(sockfd, *flags, &ifr) < 0) {
(4) on an ioctl failure, you should be printing out errno (or, better yet, its text translation) after the failure in order to figure out what went wrong:
if (ioctl(sockfd, *flags, &ifr) < 0) {
fprintf(stderr, "ioctl: flags %ld errno %d/%s\n", *flags, errno, strerror(errno));
And by the way, it seems unlikely that the errno from any of your generic_ioctl calls would be ENODEV (No such device) -- as your title implies. It seems much more likely that the errno would be EINVAL since the chances of your pointer-to-character-string forming a valid ioctl integer argument are very slim.
I have a C script that connects to a remote server with a socket and writes a command.
I have to do this as fast as possible and i need to switch from source ip addressess. The problem is, when i switch from ip addresses, the bind slows down for seconds.
I can not find a solution.
the code:
#include <sys/socket.h>
#include <sys/types.h>
#include <netinet/in.h>
#include <netdb.h>
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <unistd.h>
#include <errno.h>
#include <arpa/inet.h>
int main()
{
struct sockaddr_in source, destination = {}; //two sockets declared as previously
int sock = 0;
int n = 0;
int datalen = 0;
int pkt = 0;
char* ips[3] = {"10.0.0.1", "10.0.0.2", "10.0.0.3"};
uint8_t *send_buffer;
char recv_buffer[11];
struct sockaddr_storage fromAddr; // same as the previous entity struct sockaddr_storage serverStorage;
unsigned int addrlen; //in the previous example socklen_t addr_size;
struct timeval tv;
tv.tv_sec = 3; /* 3 Seconds Time-out */
tv.tv_usec = 0;
/*Inititalize source to zero*/
memset(&source, 0, sizeof(source)); //source is an instance of sockaddr_in. Initialization to zero
/*Inititalize destinaton to zero*/
memset(&destination, 0, sizeof(destination));
/* setting the destination, i.e our OWN IP ADDRESS AND PORT */
destination.sin_family = AF_INET;
// destination.sin_addr.s_addr = inet_addr("123.456.789.123");
destination.sin_port = htons(43);
/*---- Configure settings of the source address struct, WHERE THE PACKET IS COMING FROM ----*/
/* Address family = Internet */
source.sin_family = AF_INET;
/* Set IP address to localhost */
// source.sin_addr.s_addr = INADDR_ANY;
/* Set port number, using htons function to use proper byte order */
source.sin_port = htons(43);
/* Set all bits of the padding field to 0 */
memset(source.sin_zero, '\0', sizeof source.sin_zero); //optional
int i;
for (i=0; i<60; i++) {
/* creating the socket */
if ((sock = socket(AF_INET, SOCK_STREAM, 0)) < 0)
printf("Failed to create socket\n");
/*set the socket options*/
setsockopt(sock, SOL_SOCKET, SO_RCVTIMEO, (char *)&tv, sizeof(struct timeval));
if(inet_pton(AF_INET, ips[i%3], &source.sin_addr)<=0) //this is where is switch the ip addresses
{
printf("\n inet_pton error occured\n");
return 1;
}
/*bind socket to the source WHERE THE PACKET IS COMING FROM*/
if (bind(sock, (struct sockaddr *) &source, sizeof(source)) < 0)
printf("Failed to bind socket");
if(inet_pton(AF_INET, "94.198.154.139", &destination.sin_addr)<=0)
{
printf("\n inet_pton error occured\n");
return 1;
}
if(connect(sock, (struct sockaddr *)&destination, sizeof(destination)) < 0)
{
printf("\n Error : Connect Failed \n");
return 1;
}
printf("check\n");
n = write(sock,"is liveresults.nl\r\n",21);
if (n < 0) error("ERROR writing to socket");
while ( (n = read(sock, recv_buffer, sizeof(recv_buffer)-1)) > 0)
{
recv_buffer[n] = 0;
if(fputs(recv_buffer, stdout) == EOF)
{
printf("\n Error : Fputs error\n");
}
}
if(n < 0)
{
printf("\n Read error \n");
}
close(sock);
}
return 0;
}
edit: i must notice that it slows down afther the first loops for every ip. Because i have 3 ip addresses. After the first round, it slow down for seconds per bind.
I have to bind the local port to 0 instead of the same port as the outgoing port.
As i already asked similar questions but didn't get a solution. Hence i put this problem again with the whole code. Please tell me how can i acheive this goal
1) i have a client which sends to mainserver (127.0.0.1) a message and main server forwards it to server2 (127.0.0.2)
2) Server2 sends a message to the mainserver and mainserver forwards it to client.
Problem 1) : Although i receive the datas from client but they are not sent to server2.
Problem 2) :I dont receive any data from server2
//SERVER
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <stdio.h>
#include <unistd.h>
#include <errno.h>
#include <string.h>
#include <stdlib.h>
#include <sys/select.h>//use select() for multiplexing
#include <sys/fcntl.h> // for non-blocking
#define MAX_LENGTH 100000
#define PORT 1901
/* Select() params
* int select(int n, fd_set *readfds, fd_set *writefds, fd_set *exceptfds, struct timeval *timeout);
* FD_SET(int fd, fd_set *set);
* FD_CLR(int fd, fd_set *set);
* FD_ISSET(int fd, fd_set *set);
* FD_ZERO(fd_set *set);
*/
void error(char *message)
{
perror(message);
exit(1);
}
int main()
{
// select parameters declared
fd_set original_socket;
fd_set original_stdin;
fd_set readfds;
fd_set writefds;
struct timeval tv;
int numfd, numfd2;
// socket parameters declared
int socket_fd_ob, socket_fd_hm;
int bytes_read, bytes_sent;
char address_length, address_length2;
char recieve_data[MAX_LENGTH];
char send_data[MAX_LENGTH];
struct sockaddr_in server_address_ob, server_address_hm, client_address;
int z = 0;
//Socket creation done separately for both OBCU and HM communications
if ((socket_fd_ob = socket(AF_INET, SOCK_DGRAM, 0)) == -1)
{
error("socket()");
}
if ((socket_fd_hm = socket(AF_INET, SOCK_DGRAM, 0)) == -1)
{
error("socket()");
}
fcntl(socket_fd_ob, F_SETFL, O_NONBLOCK); //set socket to non-blocking
fcntl(socket_fd_hm, F_SETFL, O_NONBLOCK); //set socket to non-blocking
// clear the set ahead of time
FD_ZERO(&original_socket);
FD_ZERO(&original_stdin);
FD_ZERO(&readfds);
FD_ZERO(&writefds);
// add our descriptors to the set (0 - stands for STDIN)
FD_SET(socket_fd_ob, &original_socket);//instead of 0 put socket_fd_ob
FD_SET(socket_fd_ob, &readfds);
FD_SET(0,&original_stdin);
FD_SET(0, &writefds);
// the n param in select()
numfd = socket_fd_ob + 1;
numfd2 = socket_fd_hm + 1;
// wait until either socket has data ready to be recv()d (timeout 10.5 secs)
tv.tv_sec = 0.7;
tv.tv_usec = 500000;
server_address_ob.sin_family = AF_INET;
server_address_ob.sin_port = htons(1901);
server_address_ob.sin_addr.s_addr = inet_addr("127.0.0.1");
bzero(&(server_address_ob.sin_zero),sizeof(server_address_ob));
server_address_hm.sin_family = AF_INET;
server_address_hm.sin_port = htons(1901);
server_address_hm.sin_addr.s_addr = inet_addr("127.0.0.2");
bzero(&(server_address_ob.sin_zero),sizeof(server_address_hm));
// Bind socket to the particular addresses
if (bind(socket_fd_ob,(struct sockaddr *)&server_address_ob, sizeof(struct sockaddr)) == -1)
{
error("bind()");
}
if (bind(socket_fd_hm,(struct sockaddr *)&server_address_hm, sizeof(struct sockaddr)) == -1)
{
error("bind()");
}
address_length = sizeof(struct sockaddr);
address_length2 = sizeof(struct sockaddr);
printf("\nMain server waiting for client to respond...\n");
fflush(stdout);
while (1)
{
readfds = original_socket;
writefds = original_stdin;//problem
int recieve = select(numfd, &readfds, &writefds,/*NULL,*/ NULL, &tv);
int sent = select(numfd2, &readfds, &writefds,/*NULL,*/ NULL, &tv);
if (recieve == -1 || sent == -1)
{
perror("select"); // error occurred in select()
}
else if (recieve == 0 || sent == 0)
{
printf("Timeout occurred! No data after 1.5 seconds.\n");
}
else
{
// one or both of the descriptors have data
if (FD_ISSET(socket_fd_ob, &readfds)) //if set to read
{
FD_CLR(socket_fd_ob, &readfds);
if (bytes_read = recvfrom(socket_fd_ob,recieve_data,MAX_LENGTH,0,(struct sockaddr *)&server_address_ob, &address_length)>0)
{
for (z = 0; z < bytes_read; ++z) {
FD_ISSET(socket_fd_hm, &writefds);
FD_CLR(socket_fd_hm, &writefds);
//recvfrom speech recognition client and decide what to send to HM accordingly..
send_data[bytes_read] = recieve_data[bytes_read];
//block call, will wait till client enters something, before proceeding
//send the corresponding to HM
bytes_sent = sendto(socket_fd_hm,send_data,strlen(send_data)+1,0,(struct sockaddr *)&server_address_hm, &address_length2);
fflush(stdout);
}
// 02x, #x,X
printf("\n(%s , %d) rcvd: %s\n",inet_ntoa(server_address_ob.sin_addr),ntohs(server_address_ob.sin_port),recieve_data);
printf("\n(%s , %d) sent: %s\n",inet_ntoa(server_address_hm.sin_addr),ntohs(server_address_hm.sin_port),send_data);
recieve_data[bytes_read] = '\0'; //add null to the end of the buffer
send_data[bytes_read] = '\0'; //add null to the end of the buffer
}
else if (bytes_read = recvfrom(socket_fd_hm,recieve_data,MAX_LENGTH,0,(struct sockaddr *)&server_address_hm, &address_length)>0)
{
for (z = 0; z < bytes_read; ++z) {
FD_ISSET(socket_fd_ob, &writefds);
FD_CLR(socket_fd_ob, &writefds);
send_data[bytes_read] = recieve_data[bytes_read];
//block call, will wait till client enters something, before proceeding
//send the corresponding to HM
bytes_sent = sendto(socket_fd_ob,send_data,strlen(send_data)+1,0,(struct sockaddr *)&server_address_ob, &address_length2);
fflush(stdout);
}
// 02x, #x,X
printf("\n(%s , %d) rcvd: %s\n",inet_ntoa(server_address_hm.sin_addr),ntohs(server_address_hm.sin_port),recieve_data);
printf("\n(%s , %d) sent: %s\n",inet_ntoa(server_address_ob.sin_addr),ntohs(server_address_ob.sin_port),send_data);
recieve_data[bytes_read] = '\0'; //add null to the end of the buffer
send_data[bytes_read] = '\0'; //add null to the end of the buffer
}
else
{
printf("error noted");
}
} //end if set to read
} //end else
}//end while
close (socket_fd_ob);
close (socket_fd_hm);
return 0;
}
Please suggest me with code samples. i am new to this topic and didn't have a broad view yet.
Thanks
I received the error: `connect failed: connection refused` from the following code. Server side code runs fine, but when I run the client side I get the connect failed error. I am using Ubuntu.
server side run: `./server.out 1234`
client side run: `.client.out 127.0.0.1 input.txt 1234`
Client code:
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
//#include "Practical.h"
// check error
void DieWithError(char *errorMessage)
{
perror(errorMessage);
exit(1);
}
void DieWithUserMessage(const char *msg, const char *detail) {
fputs(msg, stderr);
fputs(": ", stderr);
fputs(detail, stderr);
fputc('\n', stderr);
exit(1);
}
void DieWithSystemMessage(const char *msg) {
perror(msg);
exit(1);
}
//define buffer size
enum sizeConstants {
MAXSTRINGLENGTH = 128,
BUFSIZE = 512,
};
int main(int argc, char *argv[]) {
char buffer[BUFSIZE];
//FILE *fp,*fpOut; // declare file pointer
if (argc < 3 || argc > 4) // Test for correct number of arguments
DieWithUserMessage("Parameter(s)","<Server Address> <Echo Word> [<Server Port>]");
char *servIP = argv[1]; // First arg: server IP address (dotted quad)
char *echoString = argv[2]; // Second arg: string to echo
// Third arg (optional): server port (numeric). 7 is well-known echo port
in_port_t servPort = (argc == 4) ? atoi(argv[3]) : 7;
// Create a reliable, stream socket using TCP
int sock = socket(AF_INET, SOCK_STREAM, IPPROTO_TCP);
if (sock < 0)
DieWithSystemMessage("socket() failed");
// Construct the server address structure
struct sockaddr_in servAddr; // Server address
memset(&servAddr, 0, sizeof(servAddr)); // Zero out structure
servAddr.sin_family = AF_INET; // IPv4 address family
// Convert address
int rtnVal = inet_pton(AF_INET, servIP, &servAddr.sin_addr.s_addr);
if (rtnVal == 0)
DieWithUserMessage("inet_pton() failed", "invalid address string");
else if (rtnVal < 0)
DieWithSystemMessage("inet_pton() failed");
servAddr.sin_port = htons(servPort); // Server port
// Establish the connection to the echo server
if (connect(sock, (struct sockaddr *) &servAddr, sizeof(servAddr)) < 0)
DieWithSystemMessage("connect() failed");
/*
//start reading file input from computer
char buf[1000];
fp =fopen("input.txt","r");//open the file
if (!fp){
printf("it failed!\n");
return 1;
}
while(fgets (buf, 1000, fp)!=NULL) { // take the file input value in buf char array
//printf("The input value in program.txt file: %s",buf);
printf("Received Message from server: ");
*/
size_t echoStringLen = strlen(echoString); // Determine input length
// Send the string to the server
ssize_t numBytes = send(sock, echoString, echoStringLen, 0);
if (numBytes < 0)
DieWithSystemMessage("send() failed");
else if (numBytes != echoStringLen)
DieWithUserMessage("send()", "sent unexpected number of bytes");
// Receive the same string back from the server
unsigned int totalBytesRcvd = 0; // Count of total bytes received
// Setup to print the echoed string
while (totalBytesRcvd < echoStringLen) {
// I/O buffer
/* Receive up to the buffer size (minus 1 to leave space for
a null terminator) bytes from the sender */
numBytes = recv(sock, buffer, BUFSIZE - 1, 0);
if (numBytes < 0)
DieWithSystemMessage("recv() failed");
else if (numBytes == 0)
DieWithUserMessage("recv()", "connection closed prematurely");
totalBytesRcvd += numBytes; // Keep tally of total bytes
buffer[numBytes] = '\0'; // Terminate the string!
printf("%s",buffer);
//fputs(buffer, stdout); // Print the echo buffer
}
//fpOut = fopen("gcd.txt","w"); // open the gcd txt file in write mode
//fprintf(fpOut,"%s",buffer );// write the gcd value in gcd text file
//fputc('\n', stdout);
//fclose(fpOut);
//fclose(fp);
return 0;
close(sock);
exit(0);
}
Server code:
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
//#include "Practical.h"
void DieWithError(char *errorMessage)
{
perror(errorMessage);
exit(1);
}
void DieWithUserMessage(const char *msg, const char *detail) {
fputs(msg, stderr);
fputs(": ", stderr);
fputs(detail, stderr);
fputc('\n', stderr);
exit(1);
}
void DieWithSystemMessage(const char *msg) {
perror(msg);
exit(1);
}
static const int MAXPENDING = 5; // Maximum outstanding connection requests
int main(int argc, char *argv[]) {
if (argc != 2) // Test for correct number of arguments
DieWithUserMessage("Parameter(s)", "<Server Port>");
in_port_t servPort = atoi(argv[1]); // First arg: local port
// Create socket for incoming connections
int servSock; // Socket descriptor for server
if ((servSock = socket(AF_INET, SOCK_STREAM, IPPROTO_TCP)) < 0)
DieWithSystemMessage("socket() failed");
// Construct local address structure
struct sockaddr_in servAddr; // Local address
memset(&servAddr, 0, sizeof(servAddr)); // Zero out structure
servAddr.sin_family = AF_INET; // IPv4 address family
servAddr.sin_addr.s_addr = htonl(INADDR_ANY); // Any incoming interface
servAddr.sin_port = htons(servPort); // Local port
// Bind to the local address
if (bind(servSock, (struct sockaddr*) &servAddr, sizeof(servAddr)) < 0)
DieWithSystemMessage("bind() failed");
// Mark the socket so it will listen for incoming connections
if (listen(servSock, MAXPENDING) < 0)
DieWithSystemMessage("listen() failed");
for (;;) { // Run forever
struct sockaddr_in clntAddr; // Client address
// Set length of client address structure (in-out parameter)
socklen_t clntAddrLen = sizeof(clntAddr);
printf("\nIam here\n");
// Wait for a client to connect
int clntSock = accept(servSock, (struct sockaddr *) &clntAddr, &clntAddrLen);
if (clntSock < 0)
DieWithSystemMessage("accept() failed");
// clntSock is connected to a client!
char clntName[INET_ADDRSTRLEN]; // String to contain client address
if (inet_ntop(AF_INET, &clntAddr.sin_addr.s_addr, clntName,sizeof(clntName)) != NULL)
printf("Got response from client: %s/%d\n", clntName, ntohs(clntAddr.sin_port));
else
puts("Unable to get client address");
HandleTCPClient(clntSock);
}
// NOT REACHED
}
HandleTCPClient:`#define RCVBUFSIZE 1024 /* Size of receive buffer */
void DieWithError(char errorMessage); / Error handling function */
void HandleTCPClient(int clntSocket) {
FILE *fp;
char echoBuffer[RCVBUFSIZE]; /* Buffer for echo string */
int recvMsgSize; /* Size of received message */
/* Receive message from client */
if ((recvMsgSize = recv(clntSocket, echoBuffer, RCVBUFSIZE, 0)) < 0)
DieWithError("recv() failed");
printf("Server asked file name from Client side:: %s", echoBuffer);
fp =fopen("echoBuffer","r");//open the file
if (!fp){
printf("it failed!\n");
//return 1;
}
//int i,j;
//sscanf(echoBuffer, "%d %d", &i,&j);// take the two number from client and convert string to integer.
//sprintf(echoBuffer,"%d",gcd(i,j)); // call the gcd method.
/* Send received string and receive again until end of transmission */
while (recvMsgSize > 0){ /* zero indicates end of transmission */
/* Echo message back to client */
if (send(clntSocket, echoBuffer, recvMsgSize, 0) != recvMsgSize)
DieWithError("send() failed");
/* See if there is more data to receive */
if ((recvMsgSize = recv(clntSocket, echoBuffer, RCVBUFSIZE, 0)) < 0)
DieWithError("recv() failed");
}
fclose(fp);
close(clntSocket); /* Close client socket */
}
HandleTCPclient received command from client like input.txt and check that file and send back to the client but i got segmentation fault(core dumped). here input.txt contain just one text file
enter code here
Your code is not using your supplied port, but it trying to connect to 7, you may not have a echo server running. Try changing to
in_port_t servPort = (argc ==4) ? atoi(argv[3]) : 7;