You want to program at the kernel level and filter below the packet level but don't know how to open a file? You have ambitions.
Code:
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
int main(void)
{
ssize_t bytes;
char buf[512];
int fd=open("path/to/file", O_RDONLY);
if(fd < 0)
{
perror("Couldn't open file");
return(1);
}
bytes=read(fd, buf, 512);
if(bytes <= 0)
{
perror("Couldn't read");
close(fd);
return(2);
}
close(file);
// You now have 'bytes' bytes of data read into the buffer 'buf'.
// Do other stuff here
return(0);
}
Hi,
If some one was to suggest, "increase your kernal tunables related to UDP, in particular the UDP send/recieve buffer size".... then what would they mean? :confused:
How can I find out what this current value is?
Thousand many thanks.
Neil (3 Replies)
Hi All,
I encountered a stange problem while doing a perl script to use socket. i need to transfer a file from client to sever. but error came as argument missing in send function.........Plz tell me the wt r the arguments in send and recv functions....... (0 Replies)
Hi,
Am very new to socket programming.
When we use UDP sockets to communicate between two processess,
will both the client/server socket be able to send/recv ?
meaning can sendto()/ recvfrom() be used on both server and client?
It could be useful even if anybody provide some link on socket... (1 Reply)
Hi,
I was porting ipv4 application to ipv6; i was done with TCP transports. Now i am facing problem with SCTp transport at runtime.
To test SCTP transport I am using following server and client socket programs. Server program runs fine, but client program fails giving Invalid Arguments for... (0 Replies)
I have set the receive buffer size of socket to max.
setsockopt(sd,SOL_SOCKET, SO_RCVBUF,&max,optval);
Am reading data from the socket in a loop(say max 100 bytes per recv)
while(1)
{
int rlen=recv(sd,(void *)buf, 100 , 0);
//err handle and processing
}
Assume my process is slow... (2 Replies)
char name;
printf ("Welcome to the server \n");
printf ("Enter user name: \n");
scanf ("%c", &name);
how can client send name to server:what should be the code?
int send ( int sid , const char ∗buffer Ptr , int len , int f l a g )
how can client receive ack from... (1 Reply)
Hello everybody,
Years ago i left in stand-by a project of mine where the main program was supposed to send thousands ARP frames over the socket as fast as it could; but because of a programming issue i couldn't continue it.
2 days ago I decided to solve that issue.
The thing is, when the... (4 Replies)
Discussion started by: Zykl0n-B
4 Replies
LEARN ABOUT MINIX
read
READ(2) System Calls Manual READ(2)NAME
read - read input
SYNOPSIS
#include <sys/types.h>
#include <unistd.h>
ssize_t read(int d, void *buf, size_t nbytes)
DESCRIPTION
Read attempts to read nbytes of data from the object referenced by the descriptor d into the buffer pointed to by buf.
On objects capable of seeking, the read starts at a position given by the pointer associated with d (see lseek(2)). Upon return from read,
the pointer is incremented by the number of bytes actually read.
Objects that are not capable of seeking always read from the current position. The value of the pointer associated with such an object is
undefined.
Upon successful completion, read return the number of bytes actually read and placed in the buffer. The system guarantees to read the num-
ber of bytes requested if the descriptor references a normal file that has that many bytes left before the end-of-file, but in no other
case.
If the returned value is 0, then end-of-file has been reached.
RETURN VALUE
If successful, the number of bytes actually read is returned. Otherwise, a -1 is returned and the global variable errno is set to indicate
the error.
ERRORS
Read will fail if one or more of the following are true:
[EBADF] D is not a valid descriptor open for reading.
[EFAULT] Buf points outside the allocated address space.
[EIO] An I/O error occurred while reading from the file system.
[EINTR] A read from a slow device was interrupted before any data arrived by the delivery of a signal.
[EAGAIN] The file was marked for non-blocking I/O, and no data were ready to be read.
SEE ALSO dup(2), fcntl(2), open(2), pipe(2), write(2).
4th Berkeley Distribution May 23, 1986 READ(2)
08-25-2009
