1 - I would like to log the messages that user or kernel process send to each other through the system call send, recv, sendrec and notify.
Since MINIX is a microkernel OS, I suppose that the best way is to have an TCP socket, listening in INADDR_ANY address. But, I don't know which port should I use. Can anyone help me?
2 - I've the following code:
But I get the error that, "Address family is not supported". I don't understand why?
In attachment, is the code to test IP by ARP proxy. I always use it to test a IP already existing in my cluster.
Usage:
arp_func eth0 192.168.1.1
Enviroment:
IA64, RedHat AS3.0, 2.4.21-15.EL, gcc-3.2.3-34,
"gcc -o arp_func arp_func.c"
When the code below added before... (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'm new to UNIX system calls. Can someone share your knowledge as to how exactly system calls should be executed?
Can they be typed like commands such as mkdir on the terminal itself? Also, are there any websites which will show me an example of the output to expect when a system call like... (1 Reply)
Hi all,
I am facing a problem in recv() system call i.e.. in my project i have to implement timer for sending (data) and resending purpose when there is no acknowledgement.
is there any way that recv() sys call has its own timer i.e., for ex: recv() has to wait for 10 secs.
if any... (0 Replies)
Hi,
I am having a little trouble getting notify-send to work the way I would like it to.
I am using ubuntu - karmic koala 2.6.31-19-generic #56-Ubuntu SMP
So here's the problem
run the following commands one after the other.
notify-send -i info -t 100000 -- "Hi" "world" &
notify-send -i... (3 Replies)
Hello,
how would i be able to call ps in C programming?
thanks,
---------- Post updated at 01:39 AM ---------- Previous update was at 01:31 AM ----------
here's the complete system call, ps -o pid -p %d, getpit() (2 Replies)
This isn't exactly a question. Just thought I'd share something I just wrote and found useful.
For those of you on modern linux boxen: you may be aware that there's a lovely little tool called notify-send that you can use to send notifications to the desktop. Any experienced shell-scripter could... (0 Replies)
Greetings.
I've come across a bit of a problem with notify-send syntax; and wondered if anyone out there had found a solution in the woodpile somewhere :)
Here's the snippet which is giving me trouble:notify-send 'Text to display' image_data 300, 300, , , , , /etc/image.pngOutput:Invalid... (0 Replies)
Discussion started by: LinQ
0 Replies
LEARN ABOUT LINUX
sendmmsg
SENDMMSG(2) Linux Programmer's Manual SENDMMSG(2)NAME
sendmmsg - send multiple messages on a socket
SYNOPSIS
#define _GNU_SOURCE /* See feature_test_macros(7) */
#include <sys/socket.h>
int sendmmsg(int sockfd, struct mmsghdr *msgvec, unsigned int vlen,
unsigned int flags);
DESCRIPTION
The sendmmsg() system call is an extension of sendmsg(2) that allows the caller to transmit multiple messages on a socket using a single
system call. (This has performance benefits for some applications.)
The sockfd argument is the file descriptor of the socket on which data is to be transmitted.
The msgvec argument is a pointer to an array of mmsghdr structures. The size of this array is specified in vlen.
The mmsghdr structure is defined in <sys/socket.h> as:
struct mmsghdr {
struct msghdr msg_hdr; /* Message header */
unsigned int msg_len; /* Number of bytes transmitted */
};
The msg_hdr field is a msghdr structure, as described in sendmsg(2). The msg_len field is used to return the number of bytes sent from the
message in msg_hdr (i.e., the same as the return value from a single sendmsg(2) call).
The flags argument contains flags ORed together. The flags are the same as for sendmsg(2).
A blocking sendmmsg() call blocks until vlen messages have been sent. A nonblocking call sends as many messages as possible (up to the
limit specified by vlen) and returns immediately.
On return from sendmmsg(), the msg_len fields of successive elements of msgvec are updated to contain the number of bytes transmitted from
the corresponding msg_hdr. The return value of the call indicates the number of elements of msgvec that have been updated.
RETURN VALUE
On success, sendmmsg() returns the number of messages sent from msgvec; if this is less than vlen, the caller can retry with a further
sendmmsg() call to send the remaining messages.
On error, -1 is returned, and errno is set to indicate the error.
ERRORS
Errors are as for sendmsg(2). An error is returned only if no datagrams could be sent.
VERSIONS
The sendmmsg() system call was added in Linux 3.0. Support in glibc was added in version 2.14.
CONFORMING TO
sendmmsg() is Linux-specific.
NOTES
The value specified in vlen is capped to UIO_MAXIOV(1024).
EXAMPLE
The example below uses sendmmsg() to send onetwo and three in two distinct UDP datagrams using one system call. The contents of the first
datagram originates from a pair of buffers.
#define _GNU_SOURCE
#include <netinet/ip.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/types.h>
#include <sys/socket.h>
int
main(void)
{
int sockfd;
struct sockaddr_in sa;
struct mmsghdr msg[2];
struct iovec msg1[2], msg2;
int retval;
sockfd = socket(AF_INET, SOCK_DGRAM, 0);
if (sockfd == -1) {
perror("socket()");
exit(EXIT_FAILURE);
}
sa.sin_family = AF_INET;
sa.sin_addr.s_addr = htonl(INADDR_LOOPBACK);
sa.sin_port = htons(1234);
if (connect(sockfd, (struct sockaddr *) &sa, sizeof(sa)) == -1) {
perror("connect()");
exit(EXIT_FAILURE);
}
memset(msg1, 0, sizeof(msg1));
msg1[0].iov_base = "one";
msg1[0].iov_len = 3;
msg1[1].iov_base = "two";
msg1[1].iov_len = 3;
memset(&msg2, 0, sizeof(msg2));
msg2.iov_base = "three";
msg2.iov_len = 5;
memset(msg, 0, sizeof(msg));
msg[0].msg_hdr.msg_iov = msg1;
msg[0].msg_hdr.msg_iovlen = 2;
msg[1].msg_hdr.msg_iov = &msg2;
msg[1].msg_hdr.msg_iovlen = 1;
retval = sendmmsg(sockfd, msg, 2, 0);
if (retval == -1)
perror("sendmmsg()");
else
printf("%d messages sent
", retval);
exit(0);
}
SEE ALSO recvmmsg(2), sendmsg(2), socket(2), socket(7)Linux 2014-07-08 SENDMMSG(2)