I've written a code using SOL_SOCKET protocol but getting error as 10043 (error in socket).
The code is as follows:
#include <QCoreApplication>
#include<QDebug>
//#include <windows.h>
#include <winsock2.h>
#include <ws2tcpip.h>
#include <stdlib.h>
#include <stdio.h>
/****************************************/
#pragma comment (lib, "Ws2_32.lib")
#pragma comment (lib, "Mswsock.lib")
#pragma comment (lib, "AdvApi32.lib")
/****************************************/
#define DEFAULT_BUFLEN 512
int recvbuflen = DEFAULT_BUFLEN;
char recvbuf[DEFAULT_BUFLEN];
int main(int argc, char *argv[])
{
QCoreApplication a(argc, argv);
WSADATA wsaData;
int iResult;
// Initialize Winsock
iResult = WSAStartup(MAKEWORD(2,2), &wsaData);
if (iResult != 0) {
printf("WSAStartup failed with error: %d\n", iResult);
return 1;
}
struct addrinfo *result = NULL,
*ptr = NULL,
hints;
ZeroMemory( &hints, sizeof(hints) );
//hints.ai_family = AF_UNSPEC;
hints.ai_family = AF_INET;
hints.ai_socktype = SOCK_STREAM;
hints.ai_protocol = SOL_SOCKET;
//hints.ai_protocol = IPPROTO_TCP;
#define DEFAULT_PORT "10990"
// Resolve the server address and port
iResult = getaddrinfo(argv[1], DEFAULT_PORT, &hints, &result);
if (iResult != 0) {
printf("getaddrinfo failed: %d\n", iResult);
WSACleanup();
return 1;
}
SOCKET ConnectSocket = INVALID_SOCKET;
// Attempt to connect to the first address returned by
// the call to getaddrinfo
ptr=result;
// Create a SOCKET for connecting to server
ConnectSocket = socket(ptr->ai_family, ptr->ai_socktype,
ptr->ai_protocol);
if (ConnectSocket == INVALID_SOCKET) {
printf("Error at socket(): %ld\n", WSAGetLastError());
freeaddrinfo(result);
WSACleanup();
return 1;
}
int rcvbuf = 8192; /* recv buffer size */
int z = setsockopt(ConnectSocket,SOL_SOCKET,SO_RCVBUF,
(char*)&rcvbuf,sizeof(rcvbuf));
do {
iResult = recv(ConnectSocket, recvbuf, recvbuflen, 0);
if (iResult > 0)
printf("Bytes received: %d\n", iResult);
else if (iResult == 0)
printf("Connection closed\n");
else
printf("recv failed: %d\n", WSAGetLastError());
} while (iResult > 0);
return a.exec();
}
When I run it shows::
Error in socket:10043
I googled it and found that the error is because of wrong protocol for the socket type,I tried to find the correct protocol and socket type match but couldn't find.I tried every possible socket option and protocol match.
Any body facing the same problem?
You're putting the wrong value in the ai_protocol field. It needs to be one of the IPPROTO_ constants (like e.g. IPPROTO_TCP or IPPROTO_ICMP).
SOL_SOCKET is used to set socket options (like you do later in the code).
You should normally not set that member, except to zero.
Related
A simple MPI code to catch the SIGUSR1, SIGTERM signals with signalfd unix system call
#include <assert.h>
#include <poll.h>
#include <signal.h>
#include <stdio.h>
#include <sys/signalfd.h>
#include <unistd.h>
#include <mpi.h>
/*Simple MPI Code*/
int main(int argc, char* argv[]){
MPI_Init(&argc, &argv);
int err, nbProcs, rank;
sigset_t sigset;
int fd;
MPI_Comm_size(MPI_COMM_WORLD, &nbProcs);
MPI_Comm_rank(MPI_COMM_WORLD, &rank);
****
Setup SIGALRM to be delivered via SignalFD
****
sigset_t mask;
sigemptyset(&mask);
sigaddset(&mask, SIGTERM);
sigaddset(&mask, SIGUSR1);
/* */
if (sigprocmask(SIG_BLOCK, &mask, NULL) < 0) {
printf("Failed to signalmask\n");
return -1;
}
fd = signalfd(-1, &mask, 0);
if (fd < 0)
return -1;
while (1) {
struct signalfd_siginfo si;
int ret;
ret = read(fd, &si, sizeof(si));// here the MPI process doesn't
return when I send SIGTERM or SIGUSR1
if (ret < 0)
return -1;
if (ret != sizeof(si))
return -1;
if (si.ssi_signo == SIGTERM)
printf("receive SIGTERM \\\n");
else if (si.ssi_signo == SIGUSR1)
printf("receive SIGUSR1\n");
}
MPI_Finalize();
return 0;
}
In this code, I am using signalfd to catch SIGUSR1, SIGTERM. At
ret = read(fd, &si, sizeof(si));
read() system call it doesn't return and the program dies at this point. When I use the same code without MPI simple C code it works perfect.Can anyone explain me how does signalfd works inside MPI???
I'm writing a code for extraction of peer credential by the server process connected through ipc using domain sockets to the client process. There is no error in the code but while running it I don't get the euid and gid of the peer process.
Code for server process is:
#include <stdio.h>
#include <sys/socket.h>
#include <sys/un.h>
#include <sys/types.h>
#include <unistd.h>
#include <string.h>
//#include<ucred.h>
#define SCM_CREDENTIALS
# define UNIX_PATH_MAX 100
int getpeereid(int connection_fd,uid_t euid,gid_t gid)
{
struct ucred cred;
socklen_t len = sizeof(cred);
if (getsockopt(connection_fd, SOL_SOCKET, SO_PEERCRED, &cred, &len) < 0)
return (-1);
euid =cred.uid;
gid = cred.gid;
//int passcred=1;
//setsockopt(connection_fd,SOL_SOCKET,SO_PASSCRED,(void *)&passcred,sizeof(passcred));
printf("effective user id", euid);
printf("effective group id",gid);
return 0;
}
int connection_handler(int connection_fd)
{
int nbytes;
char buffer[1024];
char msg[256];
//while(cont=recv(connection_fd,buffer,sizeof(buffer),0)>0)
//{
//write(1,buffer,cont)
nbytes = read(connection_fd, buffer, 256);
buffer[nbytes] = 0;
printf("MESSAGE FROM CLIENT: %s\n", buffer);
printf("enter the message");
scanf("%s",msg);
nbytes = snprintf(buffer, 256,msg);
write(connection_fd, buffer, nbytes);
//}
close(connection_fd);
return 0;
}
int main(void)
{
struct sockaddr_un address;
int socket_fd, connection_fd,res;
socklen_t address_length;
pid_t child;
uid_t eid;
gid_t gid;
socket_fd = socket(PF_UNIX, SOCK_STREAM, 0);
if(socket_fd < 0)
{
printf("socket() failed\n");
return 1;
}
printf("socket created\n");
unlink("./demo_socket");
/* start with a clean address structure */
memset(&address, 0, sizeof(struct sockaddr_un));
address.sun_family = AF_UNIX;
snprintf(address.sun_path, UNIX_PATH_MAX, "./demo_socket");
if(bind(socket_fd,
(struct sockaddr *) &address,
sizeof(struct sockaddr_un)) != 0)
{
printf("bind() failed\n");
return 1;
}
if(listen(socket_fd, 5) != 0)
{
printf("listen() failed\n");
return 1;
}
while((connection_fd = accept(socket_fd,
(struct sockaddr *) &address,
&address_length)) > -1)
{
// get the credentials
res=getpeereid(connection_fd,geteuid(),getgid());
if (res==0)
{
//if(res==0)
//{
child = fork();
if(child == 0)
{
/* now inside newly created connection handling process */
return connection_handler(connection_fd);
}
}
/* still inside server process */
close(connection_fd);
//}
}
close(socket_fd);
unlink("./demo_socket");
return 0;
}
the code for client
#include <stdio.h>
#include <sys/socket.h>
#include <sys/un.h>
#include <unistd.h>
#include <string.h>
#define UNIX_PATH_MAX 100
int connection_handler(int socket_fd)
{
int nbytes;
char buffer[1024];
char mesg[256];
printf("enter the message");
scanf("%s",mesg);
//printf("message is %s",mesg);
nbytes = snprintf(buffer, 256,mesg);
//fgets(buffer,256,mesg);
//i=atoi(mesg);
write(socket_fd,buffer,nbytes);
//send(socket_fd,mesg,sizeof(mesg),0);
}
//nbytes = read(socket_fd, buffer, 256);
//buffer[nbytes] = 0;
//printf("MESSAGE FROM SERVER: %s\n", buffer);
//}
int main(void)
{
struct sockaddr_un address;
int socket_fd, nbytes,i;
pid_t child;
char buffer[256];
//char mesg[100];
socket_fd = socket(PF_UNIX, SOCK_STREAM, 0);
if(socket_fd < 0)
{
printf("socket() failed\n");
return 1;
}
printf("socket created\n");
/* start with a clean address structure */
memset(&address, 0, sizeof(struct sockaddr_un));
address.sun_family = AF_UNIX;
snprintf(address.sun_path, UNIX_PATH_MAX, "./demo_socket");
if(connect(socket_fd,
(struct sockaddr *) &address,
sizeof(struct sockaddr_un)) != 0)
{
printf("connect() failed\n");
return 1;
}
child=fork();
while(child==0)
{
return connection_handler(socket_fd);
//printf("connection established\n");
//printf("enter the message");
//scanf("%s",mesg);
//printf("message is %s",mesg);
//bytes = snprintf(buffer, 256,mesg);
//fgets(buffer,256,mesg);
//i=atoi(mesg);
//write(socket_fd,buffer,nbytes);
//send(socket_fd,mesg,sizeof(mesg),0);
}
nbytes = read(socket_fd, buffer, 256);
buffer[nbytes] = 0;
printf("MESSAGE FROM SERVER: %s\n", buffer);
close(socket_fd);
return 0;
}
See http://www.thomasstover.com/uds.html for good overview.
If the server is Linux, the main problem is missing _GNU_SOURCE. Full patch below, it has a few minor changes just to get rid of gcc -Wall -Werror -pedantic -std=c99 errors and warnings.
--- server.c.orig 2014-12-06 13:23:09.138472871 +0200
+++ server.c 2014-12-06 13:21:31.962475754 +0200
## -1,3 +1,4 ##
+#define _GNU_SOURCE
#include <stdio.h>
#include <sys/socket.h>
#include <sys/un.h>
## -5,7 +6,6 ##
#include <unistd.h>
#include <string.h>
//#include<ucred.h>
-#define SCM_CREDENTIALS
# define UNIX_PATH_MAX 100
int getpeereid(int connection_fd,uid_t euid,gid_t gid)
## -20,8 +20,8 ##
//int passcred=1;
//setsockopt(connection_fd,SOL_SOCKET,SO_PASSCRED,(void *)&passcred,sizeof(passcred));
-printf("effective user id", euid);
-printf("effective group id",gid);
+printf("effective user id %d", euid);
+printf("effective group id %d",gid);
return 0;
}
## -40,7 +40,7 ##
printf("MESSAGE FROM CLIENT: %s\n", buffer);
printf("enter the message");
scanf("%s",msg);
-nbytes = snprintf(buffer, 256,msg);
+nbytes = snprintf(buffer, 256, "%s", msg);
write(connection_fd, buffer, nbytes);
//}
close(connection_fd);
## -54,8 +54,6 ##
int socket_fd, connection_fd,res;
socklen_t address_length;
pid_t child;
-uid_t eid;
-gid_t gid;
socket_fd = socket(PF_UNIX, SOCK_STREAM, 0);
if(socket_fd < 0)
I have a simple program written in C which uses termios to send a basic string to the Raspberry Pi UART and attempts to read and output the response. The Rx and Tx pins on the Raspberry Pi are connected with a jumper so whatever is sent should be immediately received.
Despite the program outputting that it successfully sent and received 5 characters for the chosen string ('Hello'), trying to print the contents of the buffer just produces one or two garbage characters.
The program:
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <fcntl.h>
#include <termios.h>
int main(int argc, char* argv[]) {
struct termios serial;
char* str = "Hello";
char buffer[10];
if (argc == 1) {
printf("Usage: %s [device]\n\n", argv[0]);
return -1;
}
printf("Opening %s\n", argv[1]);
int fd = open(argv[1], O_RDWR | O_NOCTTY | O_NDELAY);
if (fd == -1) {
perror(argv[1]);
return -1;
}
if (tcgetattr(fd, &serial) < 0) {
perror("Getting configuration");
return -1;
}
// Set up Serial Configuration
serial.c_iflag = 0;
serial.c_oflag = 0;
serial.c_lflag = 0;
serial.c_cflag = 0;
serial.c_cc[VMIN] = 0;
serial.c_cc[VTIME] = 0;
serial.c_cflag = B115200 | CS8 | CREAD;
tcsetattr(fd, TCSANOW, &serial); // Apply configuration
// Attempt to send and receive
printf("Sending: %s\n", str);
int wcount = write(fd, &str, strlen(str));
if (wcount < 0) {
perror("Write");
return -1;
}
else {
printf("Sent %d characters\n", wcount);
}
int rcount = read(fd, &buffer, sizeof(buffer));
if (rcount < 0) {
perror("Read");
return -1;
}
else {
printf("Received %d characters\n", rcount);
}
buffer[rcount] = '\0';
printf("Received: %s\n", buffer);
close(fd);
}
Outputs:
Opening /dev/ttyAMA0
Sending: Hello
Sent 5 characters
Received 5 characters
Received: [garbage]
I can't see any major problem with the code myself, but I might be wrong. I can successfully send and receive characters using PuTTY connected with the same settings, so it can't really be a hardware problem. Although I haven't tried it in PuTTY, trying to connect with anything less than 115200 baud with this program will result in nothing being received.
Where am I going wrong?
int wcount = write(fd, &str, strlen(str));
int rcount = read(fd, &buffer, sizeof(buffer));
In these lines, buffer/str are already pointers. You are passing a pointer to a pointer.
The lines should be:
int wcount = write(fd, str, strlen(str));
int rcount = read(fd, buffer, sizeof(buffer));
I need some serious help here. I have to make a TCP Server Client. When the Client connects to server using a three stage handshake. Afterwards, while the Client is running in the terminal, the user enters Linux shell commands like xinput list, ls -1, etc — something that uses standard output. The server accepts the commands and uses system() (in a fork() in an infinite loop) to run the commands and the standard output is redirected to the client, where the client prints out each line.
Afterward the server sends a completion signal of "\377\n". In which the client goes back to the command prompt asking for a new command and closes its connection and exit()'s when inputting "quit".
I know that you have to dup2() both the STDOUT_FILENO and STDERR_FILENO to the client's file descriptor {dup2(client_FD, STDOUT_FILENO). Everything works except when it comes for the client to retrieve system()'s stdout and printing it out... all I get is a blank line with a blinking cursor (client waiting on stdin). I tried all kinds of different routes to no avail... If anyone can help out I would greatly appreciate it
TCP SERVER CODE
#include <sys/types.h>
#include <sys/socket.h>
#include <stdio.h>
#include <string.h>
#include <netinet/in.h>
#include <signal.h>
#include <unistd.h>
#include <stdlib.h>
#include <errno.h>
//Prototype
void handle_client(int connect_fd);
int main()
{
int server_sockfd, client_sockfd;
socklen_t server_len, client_len;
struct sockaddr_in server_address;
struct sockaddr_in client_address;
server_sockfd = socket(AF_INET, SOCK_STREAM, 0);
server_address.sin_family = AF_INET;
server_address.sin_addr.s_addr = htonl(INADDR_ANY);
server_address.sin_port = htons(9734);
server_len = sizeof(server_address);
bind(server_sockfd, (struct sockaddr *)&server_address, server_len);
/* Create a connection queue, ignore child exit details and wait for clients. */
listen(server_sockfd, 10);
signal(SIGCHLD, SIG_IGN);
while(1) {
printf("server waiting\n");
client_len = sizeof(client_address);
client_sockfd = accept(server_sockfd,
(struct sockaddr *)&client_address, &client_len);
if(fork() == 0)
handle_client(client_sockfd);
else
close(client_sockfd);
}
}
void handle_client(int connect_fd) {
const char* remsh = "<remsh>\n";
const char* ready = "<ready>\n";
const char* ok = "<ok>\n";
const char* command = "<command>\n";
const char* complete = "<\377\n";
const char* shared_secret = "<shapoopi>\n";
static char server_msg[201];
static char client_msg[201];
static char commands[201];
int sys_return;
//memset client_msg, server_msg, commands
memset(&client_msg, 0, sizeof(client_msg));
memset(&server_msg, 0, sizeof(client_msg));
memset(&commands, 0, sizeof(commands));
//read remsh from client
read(connect_fd, &client_msg, 200);
//check remsh validity from client
if(strcmp(client_msg, remsh) != 0) {
errno++;
perror("Error Establishing Handshake");
close(connect_fd);
exit(1);
}
//memset client_msg
memset(&client_msg, 0, sizeof(client_msg));
//write remsh to client
write(connect_fd, remsh, strlen(remsh));
//read shared_secret from client
read(connect_fd, &client_msg, 200);
//check shared_secret validity from client
if(strcmp(client_msg, shared_secret) != 0) {
errno++;
perror("Invalid Security Passphrase");
write(connect_fd, "no", 2);
close(connect_fd);
exit(1);
}
//memset client_msg
memset(&client_msg, 0, sizeof(client_msg));
//write ok to client
write(connect_fd, ok, strlen(ok));
// dup2 STDOUT_FILENO <= client fd, STDERR_FILENO <= client fd
dup2(connect_fd, STDOUT_FILENO);
dup2(connect_fd, STDERR_FILENO);
//begin while... while read (client_msg) from server and >0
while(read(connect_fd, &client_msg, 200) > 0) {
//check command validity from client
if(strcmp(client_msg, command) != 0) {
errno++;
perror("Error, unable to retrieve data");
close(connect_fd);
exit(1);
}
//memset client_msg
memset(&client_msg, 0, sizeof(client_msg));
//write ready to client
write(connect_fd, ready, strlen(ready));
//read commands from client
read(connect_fd, &commands, 200);
//run commands using system( )
sys_return = system(commands);
//check success of system( )
if(sys_return < 0) {
perror("Invalid Commands");
errno++;
}
//memset commands
memset(commands, 0, sizeof(commands));
//write complete to client
write(connect_fd, complete, sizeof(complete));
}
}
TCP CLIENT CODE
#include <sys/types.h>
#include <sys/socket.h>
#include <stdio.h>
#include <string.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <unistd.h>
#include <stdlib.h>
#include <errno.h>
#include "readline.c"
int main(int argc, char *argv[])
{
int sockfd;
int len;
struct sockaddr_in address;
int result;
const char* remsh = "<remsh>\n";
const char* ready = "<ready>\n";
const char* ok = "<ok>\n";
const char* command = "<command>\n";
const char* complete = "<\377\n";
const char* shared_secret = "<shapoopi>\n";
static char server_msg[201];
static char client_msg[201];
memset(&client_msg, 0, sizeof(client_msg));
memset(&server_msg, 0, sizeof(server_msg));
/* Create a socket for the client. */
sockfd = socket(AF_INET, SOCK_STREAM, 0);
/* Name the socket, as agreed with the server. */
memset(&address, 0, sizeof(address));
address.sin_family = AF_INET;
address.sin_addr.s_addr = inet_addr(argv[1]);
address.sin_port = htons(9734);
len = sizeof(address);
/* Now connect our socket to the server's socket. */
result = connect(sockfd, (struct sockaddr *)&address, len);
if(result == -1) {
perror("ACCESS DENIED");
exit(1);
}
//write remsh to server
write(sockfd, remsh, strlen(remsh));
//read remsh from server
read(sockfd, &server_msg, 200);
//check remsh validity from server
if(strcmp(server_msg, remsh) != 0) {
errno++;
perror("Error Establishing Initial Handshake");
close(sockfd);
exit(1);
}
//memset server_msg
memset(&server_msg, 0, sizeof(server_msg));
//write shared secret text to server
write(sockfd, shared_secret, strlen(shared_secret));
//read ok from server
read(sockfd, &server_msg, 200);
//check ok velidity from server
if(strcmp(server_msg, ok) != 0 ) {
errno++;
perror("Incorrect security phrase");
close(sockfd);
exit(1);
}
//? dup2 STDIN_FILENO = server socket fd?
//dup2(sockfd, STDIN_FILENO);
//begin while(1)///////////////////////////////////////
while(1){
//memset both msg arrays
memset(&client_msg, 0, sizeof(client_msg));
memset(&server_msg, 0, sizeof(server_msg));
//print Enter Command, scan input, fflush to stdout
printf("<<Enter Command>> ");
scanf("%s", client_msg);
fflush(stdout);
//check quit input, if true close and exit successfully
if(strcmp(client_msg, "quit") == 0) {
printf("Exiting\n");
close(sockfd);
exit(EXIT_SUCCESS);
}
//write command to server
write(sockfd, command, strlen(command));
//read ready from server
read(sockfd, &server_msg, 200);
//check ready validity from server
if(strcmp(server_msg, ready) != 0) {
errno++;
perror("Failed Server Communications");
close(sockfd);
exit(1);
}
//memset server_msg
memset(&server_msg, 0, sizeof(server_msg));
//begin looping and retrieving from stdin,
//break loop at EOF or complete
while((read(sockfd, server_msg, 200) != 0) && (strcmp(server_msg, complete) != 0)) {
//while((fgets(server_msg, 4096, stdin) != EOF) || (strcmp(server_msg, complete) == 0)) {
printf("%s", server_msg);
memset(&server_msg, 0, sizeof(server_msg));
}
}
}
The output of subprocess, spawned by system(), is not connected to the calling parent process.
Try popen().
In the server, the error exits from handle_client() carefully call close(connect_fd); but the ordinary exit does not. This means that the server does not close the connection to the client, so the client waits for the server to disconnect. This is why you see the code hanging.
So I've looked around and noticed some others having a similar problem to mine. However I have yet to find a solution. I've created a client and server in Unix (Cygwin) using UDP. When I try to use sendto() in order to send a message to the server from the client, the server doesn't seem to be receiving the the packet. I've done error checking and it seems like the client isn't having a problem sending the packet, yet still the server cannot receive it correctly. The server just seems to be dead for the most part. I'm using my machine to host the client and the server and I'm attempting to connect to the server on my home address (127.0.0.1) and a random port. Any suggestions at this point would be much appreciated.
Server Code:
#include <stdio.h> /* standard C i/o facilities */
#include <stdlib.h> /* needed for atoi() / atof() */
#include <unistd.h> /* Unix System Calls */
#include <sys/types.h> /* system data type definitions */
#include <sys/socket.h> /* socket specific definitions */
#include <netinet/in.h> /* INET constants and stuff */
#include <arpa/inet.h> /* IP address conversion stuff */
#include <string.h> /* String manipulation */
#include <time.h> /* Used to to measure process execution time */
/* Server main routine - this is an iterative server
1. create a socket
2. bind the socket and print out the port number assigned
3. do forever
get next connection
handle the connection
enddo
*/
int main(int argc, char **argv)
{
int sockfd;
struct sockaddr_in servaddr, cliaddr;
int n;
//Create UDP socket
if( (sockfd = socket(AF_INET, SOCK_STREAM, 0)) < 0)
{
perror("Problem creating socket\n");
exit(1);
}
//Setup the UDP server
bzero(&servaddr, sizeof(servaddr));
servaddr.sin_family = AF_INET;
servaddr.sin_addr.s_addr = htonl(INADDR_ANY);
servaddr.sin_port = htons(0);
//Bind the UDP to the socket
if (bind(sockfd, (struct sockaddr *) &servaddr, sizeof(servaddr))<0)
{
perror("Error bind\n");
exit(1);
}
//Print the port for the UDP server
int length = sizeof( servaddr );
if (getsockname(sockfd, (struct sockaddr *) &servaddr, &length) < 0)
{
perror("Error getsockname\n");
exit(1);
}
printf("The Server passive socket port number is %d\n",ntohs(servaddr.sin_port));
//Send/Recv from client
char msg[100];
for(;;)
{
socklen_t len = sizeof(cliaddr);
if( recvfrom(sockfd, msg, 100, 0, (struct sockaddr*) &cliaddr, &len) < 0)
{
perror("Error on recv\n");
exit(1);
}
printf("Msg: %s\n", msg);
//read(sockfd, msg, 10);
//sendto(sockfd, msg, n, 0, (struct sockaddr*) &cliaddr, len);
}
close(sockfd);
return 0;
}
Client Code:
#include <stdio.h> /* standard C i/o facilities */
#include <stdlib.h> /* needed for atoi() */
#include <unistd.h> /* Unix System Calls */
#include <sys/types.h> /* system data type definitions */
#include <sys/socket.h> /* socket specific definitions */
#include <netinet/in.h> /* INET constants and stuff */
#include <arpa/inet.h> /* IP address conversion stuff */
#include <string.h>
/* client program:
The following must passed in on the command line:
name of the server (argv[1])
port number of the server (argv[2])
*/
int main( int argc, char **argv )
{
int sockfd;
struct sockaddr_in servaddr;
int n;
//Ensure we have full args
if (argc != 3)
{
printf("Usage: client <server name> <server port>\n");
exit(1);
}
//Setup the port number
bzero(&servaddr, sizeof(servaddr));
servaddr.sin_family = AF_INET;
servaddr.sin_port = htons(atoi(argv[2]));
//Setup the client IP
//inet_pton(AF_INET, argv[1], &servaddr.sin_addr)) <= 0
if( inet_aton(argv[1], &servaddr.sin_addr) == 0)
{
perror("Error with server IP\n");
exit(1);
}
//Create socket
if( (sockfd = socket(AF_INET, SOCK_DGRAM, 0)) < 0)
{
perror("Error on socket\n");
exit(1);
}
/*if (connect(sockfd,(struct sockaddr *) &servaddr, sizeof(servaddr)) < 0 )
{
printf("Problem connecting socket\n");
exit(1);
}*/
//Send msg
char msg[10] = "123456789";
for(;;)
{
socklen_t len = sizeof(servaddr);
if( (sendto(sockfd, msg, strlen(msg), 0, (struct sockaddr*) &servaddr, len)) < 0 )
{
perror("Error on sendto():\n");
exit(1);
}
//write(sockfd, msg, strlen(msg));
//n = recvfrom(sockfd, msg2, 10, 0, NULL, NULL);
//printf("Msg: %s\n", msg2);
}
close(sockfd);
return 0;
}
First, your sender just sends data as fast as it possibly can, whether or not anyone or anything is listening. That's not a good thing to do.
Second, your receiver passes msg through to a %s printf specifier. But %s is only for C-style strings, and msg is not a C-style string (nothing puts a zero byte on the end of it). You also throw the return value of recvfrom away, so you can't convert it into a string because you have no idea how many of its bytes are valid.
Third, your server is creating a SOCK_STREAM socket!