hi...
i have made this client server prog with UDP sockets but im not getting the output. the client sends the message but the server just keeps on waiting. Im running the prog an a solaris 10 box...
hi all, newbie here, i'm working on mac os x and i'm trying to stream some info using udp from the terminal to another app that listens for osc messages on the same machine. but the man page on udp is pretty cryptic. my question is whether anyone has a recommendation for a good tutorial covering... (0 Replies)
Just like concurrent tcp server, anyone know how to design the concurrent udp server with the thread? it's best to give some basic examples,thanks (0 Replies)
Hi there,
Does anyone know of a place that will give details for each of the following UDP parms? I've found documentation on there size limits but not what they will do or affect if changed.
udp_xmit_hiwat
udp_xmit_lowat
udp_recv_hiwat
udp_max_buf ... (1 Reply)
Dear guys,
I am facing the most weird problem I have ever encountered!
Ok here is the situation:
From my dns query.log file - it is generated using usual bind9 logging:
logging {
channel query.log {
file "/var/log/bind9/query.log" versions 10 size 2m;
severity debug 2;... (0 Replies)
Hi,
I can see "udpInOverflows" errors when I execute 'netstat -s' on my Solaris box.
The number of errors are small - about 40.
e.g.
$ netstat -s|grep udp
UDP udpInDatagrams =1249190732 udpInErrors = 0
udpOutDatagrams =31663030 udpOutErrors = 0... (1 Reply)
Hello,
I would like to ask you for a help. I need to program in C print server which is based on connectionless protocol UDP. The problem is that I am not experienced in programming network applications, I can help myself with some other answered questions on this forum about network apps in C,... (1 Reply)
Hi,
I know tcp port tunneling can be done using ssh/putty. how about udp?
I have a scenario where a license server handsout licenses to machines in that network ONLY. I have a windows machine in a different subnet and even though the client software can see license server, while using the... (6 Replies)
Performing UDP tunneling through an SSH connection
Found this while looking for a way to temporarily forward SNMP requests across otherwise disconnected networks. Might be useful for someone else, too. (1 Reply)
hi guys
My linux server have SNMP configure port by default is 161 (UDP)
now my monitor team - who are using Nagios - say the server are not being monitor
so check netstat -lnu and I see all is OK and snmp service is running fine
what else should I check about this port 161? to see if it is... (0 Replies)
Discussion started by: karlochacon
0 Replies
LEARN ABOUT MOJAVE
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,
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. See also BUGS.
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).
BUGS
If an error occurs after at least one message has been sent, the call succeeds, and returns the number of messages sent. The error code is
lost. The caller can retry the transmission, starting at the first failed message, but there is no guarantee that, if an error is
returned, it will be the same as the one that was lost on the previous call.
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 addr;
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);
}
addr.sin_family = AF_INET;
addr.sin_addr.s_addr = htonl(INADDR_LOOPBACK);
addr.sin_port = htons(1234);
if (connect(sockfd, (struct sockaddr *) &addr, sizeof(addr)) == -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)COLOPHON
This page is part of release 4.15 of the Linux man-pages project. A description of the project, information about reporting bugs, and the
latest version of this page, can be found at https://www.kernel.org/doc/man-pages/.
Linux 2018-02-02 SENDMMSG(2)