Hello everyone!I would appreciate any help you could give me,I have to make a program of an atm machine using client server sockets and semaphores.I know how to construct an ATM in c++ but don't know anything about unix c.The problem is that Don't know what to do and how to link the two programs together.
I have written a socket program in C under RedHat Linux 6.2. This program is using SOCK_STREAM (TCP) to connect to any ip address at port # 23. The program is hosted on the linux machine and works well with Cisco routers. But when I am trying to connect to the same linux machine, it does not return... (4 Replies)
We just recently upgraded our T1 wan link to a 10Mbit ATM link.
Windows pc's seem fine and get great speed, however we have 2 Sco unix box's that seem really slow at FTPing now.
both Sco box's are
SCO OpenServer Enterprise System (ver 5.0.5m)
compaq ML530's
I'm not really sure what to... (4 Replies)
Hi, yes i belong to that duummies group of people so here is the question that i need someone to explain it to me and posiblly to answere it to me in a plain english.
This is the question:
Describe the concept of “client-server” software. Discuss what each side
of the equation... (2 Replies)
Hi all,
i am having a doubt regarding how to get the acknowledgement(reply) from client to server & how to recieve at the server....imagine there r 8 frames...we have to send first 4frames at a time and after tat we have to receive and ack and only after receiving an ack we have to send... (1 Reply)
Hi,
I have installed the vmware server on my debian os and has several clients connected to it. Is there any script that enable the server to restart the client automatically??
Can anyone help.
Thanks in advance (3 Replies)
Problem
- Linux Client/Server Socket Application: Preventing Client from quitting on server crash
Hi,
I am writing a Linux socket Server and Client using TCP protocol on Ubuntu 9.04 x64.
I am having problem trying to implement a scenario where the client should keep running even when the... (2 Replies)
Hi All,
I need your expertise in finding a way to solve my problem.Please excuse if this is not the right forum to ask this question and guide me to the correct forum,if possible.
I am a DBA and on a daily basis i have to ftp huge dump files from my company server to my laptop and then... (3 Replies)
Hello,
Please I would create a client and a server in C that communicate frequently. The client sends "hello message" to the server, the server waits a few minutes and sends a "hello message" to the client, the client sends again "hello server ".. etc up to 15 minutes
Can you guide me... (3 Replies)
Hello,
Please, is there on unix.com the source code of a client C and server C: as shown in following figure:
File:InternetSocketBasicDiagram zhtw.png - Wikipedia, the free encyclopedia
Thank you so much for help (1 Reply)
hi, i am new to unix,
cuold u send some sftp acripts to send files to dev server to clint server, (1 Reply)
Discussion started by: Koti.annam
1 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)