Re: [PATCH] ip.7: Add not supported by SOCK_STREAM to socket options

[Oliver Crumrine]

On Sat, Mar 16, 2024 at 08:33:36PM +0100, Alejandro Colomar wrote:
> Hi Oliver,
> 
> On Wed, Mar 13, 2024 at 02:27:17PM -0400, Oliver Crumrine wrote:
> > > Hi Alex,
> > > I apologize for your repeated troubles with my test program.
> > > I have attached a video of myself using it in the method that I
> > > described to you. (I emailed you off-list as to avoid sending a 12
> > > MB video to the whole list)
> > >
> > > If you are using it in the same way that works for me, I don't know
> > > what the problem is. If I could've been clearer in my instructions, let
> > > me know for the future.
> > >
> > > Thanks,
> > > Oliver
> > 
> > Hi Alex,
> > Were you able to make any progress whatsoever with this test program?
> 
> I'm sorry, but I haven't been able to reproduce the behavior.  The test
> programs have several problems which I reported in previous mails.
> Maybe there's something that makes it unstable and in your system
> behaves differently?  Please clean up those examples, and try to run
> them in a different system, and maybe then I can reproduce it.
> 
> Have a lovely day!
> Alex
> 
> 
> $ uname -a
> Linux debian 6.8.0-rc7-alx-dirty #3 SMP PREEMPT_DYNAMIC Mon Mar  4 15:24:33 CET 2024 x86_64 GNU/Linux
> 
> -- 
> <https://www.alejandro-colomar.es/>
Hi Alex,
I have cleaned up my test programs. I have also tested them on other
systems (including on systems which I had installed the rc7 kernel
onto). In the very slight chance that your netcat isn't working, (very 
narrow chances, but still there), I have attached client programs to go 
along with the servers.
Thanks,
Oliver

#include <stdio.h>
#include <err.h>
#include <string.h>
#include <stdlib.h>
#include <arpa/inet.h>
#include <sys/socket.h>
#include <unistd.h>

#define PORT 8888 //The port on which to send data
#define ADDR "127.0.0.1" //The internet address to send packets to

int main(void){
	int s;
	struct sockaddr_in server_addr;

	int send_len;
	char buf[] = "testing 1 2 3\n";

	s = socket(AF_INET, SOCK_DGRAM, IPPROTO_UDP);
	if(s == -1){
		err(1, "error creating socket");
	}

	memset((char*)&server_addr, 0, sizeof(server_addr));
	
	server_addr.sin_family = AF_INET;
	server_addr.sin_port = htons(PORT);
	if(inet_pton(AF_INET, ADDR, &server_addr.sin_addr) != 1){ //I realize I'm checking the return value differently here. If you read the man page for inet_pton, it'll make sense.
		err(1, "error converting network address");
	}

	if(sendto(s, buf, strlen(buf), 0, (struct sockaddr*)&server_addr, sizeof(server_addr)) == -1){
		err(1, "error sending data");
	}
	
	close(s);


}
#include<stdio.h>
#include<err.h>
#include<string.h>
#include<stdlib.h>
#include<arpa/inet.h>
#include<sys/socket.h>
#include<unistd.h>

#define PORT 8888	//The port on which to listen for incoming data


//Hi Alex,
//These are the two lines that allow you to switch between the three socket options outlined in my patch
//The socket options tell the kernel to add a control message (cmsg), allowing the program
//to recieve the data it is requesting. The three options are: IP_RECVTOS for the type of service byte,
//IP_RECVORIGDSTADDR for the orignial dst address, and IP_PKTINFO for some random packet info.
#define SOCKOPT IP_RECVORIGDSTADDR
//This field is synonymous with the above one. Valid options are: IP_TOS, IP_ORIGDSTADDR, and IP_PKTINFO
#define RECIVEOPTION IP_ORIGDSTADDR

int main(void){
	struct sockaddr_in local_addr;
	
	int s;
	int recv_len;
	char buf[BUFSIZ];
	
	s = socket(AF_INET, SOCK_DGRAM, IPPROTO_UDP);
	if (s == -1){
		err(1, "error creating socket");
	}
	
	memset((char *) &local_addr, 0, sizeof(local_addr));
	
	local_addr.sin_family = AF_INET;
	local_addr.sin_port = htons(PORT);
	local_addr.sin_addr.s_addr = htonl(INADDR_ANY);

	int yes = 1;
	if(setsockopt(s, IPPROTO_IP, SOCKOPT, &yes, sizeof(yes)) == -1){
		err(1, "error setting socket option");
	}


	if(bind(s, (struct sockaddr*)&local_addr, sizeof(local_addr) ) == -1){
		err(1, "error binding to port. try changing it or running as root");
	}

	while(1){
		struct msghdr mhdr;
		struct iovec iov[1];
		struct cmsghdr *cmhdr;
		char control[1000];
		char databuf[1500];
		unsigned char tos = 0;
		
		mhdr.msg_name = &local_addr;
		mhdr.msg_namelen = sizeof(local_addr);
		mhdr.msg_iov = iov;
		mhdr.msg_iovlen = 1;
		mhdr.msg_control = &control;
		mhdr.msg_controllen = sizeof(control);
		iov[0].iov_base = databuf;
		iov[0].iov_len = sizeof(databuf);
		memset(databuf, 0, sizeof(databuf));	
		
		//this is blocking
		if ((recv_len = recvmsg(s, &mhdr, 0)) == -1){
			err(1, "recvmsg");
		}
		cmhdr = CMSG_FIRSTHDR(&mhdr);
		while (cmhdr) {
			printf("cmsg recieved\n");
    		    if (cmhdr->cmsg_level == IPPROTO_IP && cmhdr->cmsg_type == RECIVEOPTION) {
    		        //read the byte recieved
			    tos = ((unsigned char *)CMSG_DATA(cmhdr))[0];
    		    }
    		    cmhdr = CMSG_NXTHDR(&mhdr, cmhdr);
    		}
		//print out the first byte of data recieved in hex. You can verify this in wireshark if you like.
    		printf("data read: %sbyte = %02X\n", databuf, tos); 	
		
	}

	close(s);
	return 0;
}
#include <stdio.h>
#include <err.h>
#include <string.h>
#include <stdlib.h>
#include <arpa/inet.h>
#include <sys/socket.h>
#include <unistd.h>

#define PORT 8888 //The port on which to send data
#define ADDR "127.0.0.1" //The internet address to send packets to

int main(void){
	int s;
	struct sockaddr_in server_addr;

	int send_len;
	char buf[] = "testing 1 2 3\n";

	s = socket(AF_INET, SOCK_STREAM, 0);
	if(s == -1){
		err(1, "error creating socket");
	}

	memset((char*)&server_addr, 0, sizeof(server_addr));
	
	server_addr.sin_family = AF_INET;
	server_addr.sin_port = htons(PORT);
	if(inet_pton(AF_INET, ADDR, &server_addr.sin_addr) != 1){ // I realize I'm checking the return value differently here. If you read the man page for inet_pton, it'll make sense.
		err(1, "error converting network address");
	}

	if(connect(s, (struct sockaddr*)&server_addr, sizeof(server_addr)) == -1){
		err(1, "error connecting");
	}
	if(send(s, buf, strlen(buf), 0) == -1){
		err(1, "error sending data");
	}
	
	close(s);


}
#include<stdio.h>
#include<err.h>
#include<string.h>
#include<stdlib.h>
#include<arpa/inet.h>
#include<sys/socket.h>
#include<unistd.h>

#define PORT 8888	//The port on which to listen for incoming data


//Hi Alex,
//These are the two lines that allow you to switch between the three socket options outlined in my patch
//The socket options tell the kernel to add a control message (cmsg), allowing the program
//to recieve the data it is requesting. The three options are: IP_RECVTOS for the type of service byte,
//IP_RECVORIGDSTADDR for the orignial dst address, and IP_PKTINFO for some random packet info.
#define SOCKOPT IP_RECVORIGDSTADDR
//This field is synonymous with the above one. Valid options are: IP_TOS, IP_ORIGDSTADDR, and IP_PKTINFO
#define RECIVEOPTION IP_ORIGDSTADDR

int main(void){
	struct sockaddr_in local_addr;
	
	int s;
	int recv_len;
	char buf[BUFSIZ];
	
	s = socket(AF_INET, SOCK_STREAM, 0);
	if (s == -1){
		err(1, "error creating socket");
	}
	
	memset((char *) &local_addr, 0, sizeof(local_addr));
	
	local_addr.sin_family = AF_INET;
	local_addr.sin_port = htons(PORT);
	local_addr.sin_addr.s_addr = htonl(INADDR_ANY);

	int yes = 1;
	if(setsockopt(s, IPPROTO_IP, SOCKOPT, &yes, sizeof(yes)) == -1){
		err(1, "error setting socket option");
	}


	if(bind(s, (struct sockaddr*)&local_addr, sizeof(local_addr) ) == -1){
		err(1, "error binding to port. try changing it or running as root");
	}
	
	if(listen(s, 10) == -1){ //10 is the backlog of un-accepted connections. its just an arbitrary number
		err(1, "error listening on port");
	}

	while(1){
		int connfd = accept(s, (struct sockaddr*)NULL, NULL);
		if(connfd == -1){
			err(1, "error accepting connection");
		}
		if(setsockopt(s, IPPROTO_IP, SOCKOPT, &yes, sizeof(yes)) == -1){ //stream sockets should have this set on the connected socket as well. I left it above for uniformity between the two programs.
			err(1, "error setting socket option");
		}
	
		struct msghdr mhdr;
		struct iovec iov[1];
		struct cmsghdr *cmhdr;
		char control[1000];
		char databuf[1500];
		unsigned char tos = 0;
		
		mhdr.msg_name = &local_addr;
		mhdr.msg_namelen = sizeof(local_addr);
		mhdr.msg_iov = iov;
		mhdr.msg_iovlen = 1;
		mhdr.msg_control = &control;
		mhdr.msg_controllen = sizeof(control);
		iov[0].iov_base = databuf;
		iov[0].iov_len = sizeof(databuf);
		memset(databuf, 0, sizeof(databuf));	
		
		//this is blocking
		if ((recv_len = recvmsg(connfd, &mhdr, 0)) == -1){
			err(1, "recvmsg\n");
		}
		cmhdr = CMSG_FIRSTHDR(&mhdr);
		while (cmhdr) {
			printf("cmsg recieved\n");
    		    if (cmhdr->cmsg_level == IPPROTO_IP && cmhdr->cmsg_type == RECIVEOPTION) {
    		        //read the byte recieved
			    tos = ((unsigned char *)CMSG_DATA(cmhdr))[0];
    		    }
    		    cmhdr = CMSG_NXTHDR(&mhdr, cmhdr);
    		}
		//print out the first byte of data recieved in hex. You can verify this in wireshark if you like.
    		printf("data read: %sbyte = %02X\n", databuf, tos); 	
		close(connfd);
	}

	close(s);
	return 0;
}