Programming :: Server Socket Assigned By Children Processes ?
Aug 27, 2010
I am currently programming a suite of daemons in c++ on CentOS 64. More or less all those daemons are SOAP servers, with the SOAP part handled by gSOAP.
One of the daemons is a monitor sitting on a certain server and more or less just checking if the other daemons are up and running - but also offering a SOAP interface to get the 'current situation' on the machine.
Whenever the detected situation does not correspond to the defined (i.E. a process which should be is not running) it is started up.
This part, I implemented via a system() call that starts the other process.
I was a little confused when lately often this monitoring process would not start because it could not bind its server port - the one the SOAP server is listening on.
And confusion got bigger when netstat told me that the port is assigned to one of the processes that were before started by the monitor..?
Even better: if I then kill the process of which netstat tells me it holds the port, the next netstat shows the next monitor-started process as the one listening on the port..
Only if I kill all the processes that were started by the monitor, the port is released and I am able to launch the monitor again.
Now I wonder: why does this port get 'reassigned' to the children - and most of all: how can I prevent this from happening?
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May 20, 2011
What I need is, given a process id, list all his children without any clutter (table header, other columns than the pid) What I have is :
ps h --ppid $PID Which gives me:
26277 pts/13 S+ 0:10 cmd1
26280 pts/13 S+ 0:10 cmd2
Using h allow me to hide the table header. Is there a way to tell ps to not print the pts/13 S+ 0:10 cmd part in order to get a list of children process ids separated by carriage return?
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Mar 8, 2011
iam just trying to connect to server which accepts one client and server will read(blocking operation) infinitely, but After closing the client socket the server "read operation" is returning zero and "errno variable(in errno.h)" value is also zero. how can i detect whether a client socket is closed/active..?
client.c
Serv_Addr.sin_family = AF_INET;
Serv_Addr.sin_addr.s_addr = inet_addr("127.0.0.1");
Serv_Addr.sin_port = htons(26553);
if( 0 > connect (Serv_Fds,&Serv_Addr,sizeof(Serv_Addr)) )
{
perror("connect");
return 0;
[Code]....
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May 16, 2011
i have a server program which accept multiple client connection and am using polling. like every 2 secs it will look to client whether any data is received after it binded. i have used setitimer but there is runtime error i got.. the server accept all client connection but doesn't execute any msg which client sent.
#include<stdio.h>
#include<stdlib.h>
#include<sys/socket.h>
#include<sys/types.h>
#include<netdb.h>
#include<unistd.h>
#include<pthread.h>
#include<string.h>
[Code]....
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Mar 16, 2010
I am looking to be able to connect to an IRC server in a C program. I have followed some instructions from an old book I have however it doesn't seem to be working. I've tried connecting to localhost on my ssh port and it still doesn't want to work. This is what I have so far as a piece of skeleton test code:
Code:
#include<sys/types.h>
#include<stdio.h>
#include<stdlib.h>
#include<sys/socket.h>
#include<unistd.h>
#include<netinet/in.h>
#include<arpa/inet.h>
[Code]....
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Jul 6, 2010
i'm writing a simple program of client socket program. Here below is the code sample which i'm writing...
Code:
//tcp_client.c
#include <stdio.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <netdb.h>
#include<string.h>
#include<stdlib.h>
[Code].....
the above code works fine.if we copmile and run ./a.exe 192.xx.xx.xxx 1111 and press enter it works fine..everytime it asks "Please enter the message: " and if give that will be displayed in server. but my problem is i dont want to print everytime "Please enter the message: " i just want to feed some words one by one to the socket.
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Mar 30, 2009
im getting that error in my code for some reason. I compiled my code, and when i try to run this server it throws me an error on my call to setsocketopt(). The only way it can reach that part of my loop is if it succeeds when it calls sock() so I dont understand why the error says its an operation on a non-socket. Im just trying to set up a server to pass messages from a client to it a viceversa. Here is the code:
Code:
int main()
{
int socket_fd, new_socket_fd, k;
struct addrinfo hints, *server_info, *p;
struct sockaddr_storage peer_address;
code....
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Jul 22, 2010
I am facing an issue where the process starts hanging. When I closely look at the logs I come to know that some of the child processes that are forked by the parent process are not finished.
1) Is it possible that the child processes that are not finished occupy the socket memory of the parent process and ultimately a point is reached where no socket memory is available to fork new child processes.
2) What is the standard limit of socket memory in linux?
3) What is the fate of such child processes (as I have mentioned above)?
4) How to debug such cases so that the exact problematic area is identified?
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Mar 17, 2011
I want to built a Chat Program (based on Socket connection) between client and server. I use the GTK+ &GLADE graphic tool. Can you send me the code for this program or any material to learn. Also, I want to know how to show the input to text view (in GTK+&Glade).
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Aug 6, 2010
Reading some examples on net and copying some codes I was able to build a (frankstein) server that accept connection from one client and receive and send messages to it. The big problem that shows up is that I don't know when client disconnects from my server.
I've been looking for a solution, but no success. I'd read about SO_KEEPALIVE option (which could solve my problem), but I don't know how to use it (how to check the value of it).
I can't use ping because the server (machine) could be running, but not the client (software).
Anyone knows a good tutorial or how to (for beginners like me xD) of TcpIp sockets using c/c++ and how to detect when a client disconnect?
I don't know sockets very well.
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Jan 2, 2009
I'm trying implement a small server for a university work, my server is creating, binding and listening but it don't accept any connection, these are the files I'm using in server:
Code:
// Definition of the Socket class
#ifndef SOCKET_H
#define SOCKET_H
#include <sys/types.h>
code....
I've made a client just for test it, but no ones run well, the server is always returning -1 when accept is called!!
What should I do to send and receive messages in this server??
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Dec 7, 2010
Anyone knows the difference between a socket and TCP connection for connecting to an external system?
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Apr 19, 2010
I'm building a simple(?) socket server using threads to serve up a few requests. The spec is such that I have to listen to three ports at once, so I decided to use pthread to create three separate threads that would wait for connections, then spawn new threads to handle them.
The problem is that when I do this, for some reason the program never enters the wait loop and instead terminates (All three threads did get created since the messages get printed properly.) It gets to the line which prints "???", but not the line after the accept() call.I don't see an open port when I check for one either so I'm 99% sure they're terminating.Basically I have a main() method which has three calls to pthread_create, which should result in three threads being run that all wait for connections (listenOnPort). After each thread creation I print some info to make sure it's actually being created.
By the way, when I just run listenOnPortwithout threading, the server appears to enter the loop correctly and seems to be waiting for requests. It's only when I run the functions as threads that the problem seems to happen.The source is attached below. Any help will be appreciated. Much of the code is borrowed from a website (I can't post it because I am new here.) You need not worry about the handler_ methods because those are just methods that are run by the threads themselves.
Also--the original source was in C and I changed it to C++. Should I just use C?
server.h Code: /*
* server.h
[code]....
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Mar 8, 2011
I have a server listening on incoming client connections. Once the client establishes SSL connection with the server, the server waits on read() from the client. Only Client can disconnect the connection. I want to have a timer in the server program to wait for x secs after read() and then disconnect the Client connection.
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May 11, 2011
i have problem in socket programming, while displaying received message in file,i got a problem... i cant able to write it in the file.... this is the code....
Code:
/* tcpserver.c */
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <stdio.h>
[Code]....
now my problem is run time error i can able to create file but i cant able to write file....log.txt contain nothing.... as here i have give sample code... dont say not initialising function and all.... i have initialised , please only see func1() - my problem is only not able to write msg which i got received from the client..
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Aug 25, 2010
how to use socket programming in order to implement chatting feature
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Dec 5, 2010
When sending data over the socket, the sending socket includes 0x00 after each sent byte. I wonder how this can be avoided -- I just want to transfer the data in the tx_buffer as it is.
# ./serv &
[1] 6895
# ./EUG 127.0.0.1
EUG: Data to be transmitted: 0x35 0x32 0x30 0xff 0x03 0x31
EUG: Data - #Bytes transmitted: 6
./serv: Here is the message: '5'
[Code]...
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Mar 28, 2011
Is it possible to swap a client ip and port ? This is what I am trying to do. Let say you have Comp1 and Comp2 And you have Server between them. My goal is to get Comp1 and Comp2 know each others IP So Comp1 connects to server And server stores comp1's IP In a text file or other place And Comp2 connect to server And server also stores his info And then both comp1 and comp2 dowload the tex file And use the info on it.
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Jan 30, 2011
How can we build a packet using C?we have a structure called sockaddr_in which is use to for IPv4,so that we can define address,port and etc in this way:
Code:
struct sockaddr_in sock;
sock.sin_family=AF_INET;
[code]...
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Nov 11, 2010
This is my main question:Quote: In raw socket sniffing: how do I copy data from a structure into a char[] or pointer? My problem: I started doing some raw socket programming in OpenWRT (I'm a newbie) for research. It's been a long time since the last time I programmed in C, so here's my newbie question/problem.
I'm receiving packets and using an .h file with the structures to get the information of each 802.11 packet in monitor mode (attached to this post).My (simple) goal is to get the Tx MAC Address. No luck. This is my "read the prism header" function:
Code:
ParsePrismHeader(unsigned char *packet,int len)
{
wlan_header *wlan;ieee_802_11_header *i802;u_int16_t eth_type;
unsigned char *mac;unsigned char *mac2;
wlan = (wlan_header *)packet;
i802 = (ieee_802_11_header *)(packet + wlan->msglen);
[Code]...
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Jul 23, 2010
I am currently doing a research on video transmission over wireless LAN. I tend to transmit my offline file (xx.svc) from server to client.It may sound stupid (since I have a very little knowledge about c programming and raw socket), but my biggest challenges is that when I want to write the file to the buffer, how actually to define/include the file at the programming coding? where I need to locate the file? Is it at the same folder with my c programming, or somewhere in the linuxinclude folder?
Can anyone just give a simple example on how to include a file and write it into a buffer before send it through raw socket.
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Jul 21, 2010
Where is the perl module for programming with sockets?
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Jan 15, 2010
I have currently had the need to go back to basic socket programming, and implemented a simple udp packet sender. But I realized I needed to be able to select which network interface to send the packets from.
The reason is so that one of the interfaces has vlan tagging, and I need my UDP packets to be accordingly vlan tagged. For example, one of the interfaces is eth1.200.
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Jun 22, 2009
this is my client and server. I can receive text file. but I can't send other type of file like PDF,Docx,Odt
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Apr 26, 2010
when i assign ip manually to a machine it gets ping by server and it also itself pings server but when i chose to use client machine as dhcp , so that it can directly get assigned ip from server, it does not get ip, instead random ip is provided which is out of range specified at server side in /etc/dhcpd.conf file.
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Nov 18, 2009
I'm stumped here as it seems like after an update etho:0 has assigned itself 2 x IP Addresses. I don't understand how this happened or how to fix it so some help would be great as I cannot access cPanel while it's like this or my sub directories.Here is a print of ifconfig
-bash-3.2# ifconfig
eth0 Link encap:Ethernet HWaddr AA:01:5F:9A:FE:26
inet addr:95.154.254.38 Bcast:95.154.254.38 Mask:255.255.255.255
[code]....
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Apr 8, 2010
I am creating a new user for my son, but I don't want him to have access to M15+ games that are installed (eg Freedoom). Is there a way to deny a user's access to individual programs (or groups of programs). Also for the moment, I would really want him to only have access to a folder with his name on it and not to all of my drives and files on them. Is this possible? I couldn't find it anywhere...
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Nov 1, 2010
i hav configure dhcp server. but the ip is not getting assigned to my client machine.
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Aug 27, 2010
Iv got an assignment to complete and I'm stuck at the basic level.
A part of the assigned problem is :
The main process will read the file, and will create N number of child processes (Where N is taken as input) as early as possible before all the children starts its execution. Before creation of each child, the main process should read the file to store all the required data in then corresponding data structure. Child processes should not read the file for getting their information.
As far as my knowledge about this , the child executes before the parent. How do I make the parent not pass the control to it's children before it finishes creating all the children?
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Jan 24, 2011
Has anyone had an issue with gdb not being able to send a UDP msg across a socket?
I have ComponentA sending a msg to ComponentB utilizing gdb. ComponentB gets the msg. ComponentB sends a msg to ComponentC. ComponentC does stuff to the msg and sends a msg back to ComponentB using gdb.
ComponentB never seems to receive the 2nd message.
If I don't use gdb the messages Tx and Rx without an issue.
I'm flying blind without gdb to figure out a different bug.
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