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Message-ID: <ZfZPTsdxElzcqtpe@debian>
Date: Sun, 17 Mar 2024 03:02:53 +0100
From: Alejandro Colomar <alx@...nel.org>
To: Oliver Crumrine <ozlinuxc@...il.com>
Cc: linux-kernel@...r.kernel.org, linux-man@...r.kernel.org
Subject: Re: [PATCH] ip.7: Add not supported by SOCK_STREAM to socket options
Hi Oliver,
On Sat, Mar 16, 2024 at 02:41:13PM -0400, Oliver Crumrine wrote:
> 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
I still get warnings when compiling them. There's clearly dead code in
them.
alx@...ian:~/tmp$ cc -Wall -Wextra ds.c -o ds
ds.c: In function ‘main’:
ds.c:26:14: warning: unused variable ‘buf’ [-Wunused-variable]
26 | char buf[BUFSIZ];
| ^~~
alx@...ian:~/tmp$ cc -Wall -Wextra dc.c -o dc
dc.c: In function ‘main’:
dc.c:16:13: warning: unused variable ‘send_len’ [-Wunused-variable]
16 | int send_len;
| ^~~~~~~~
> #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));
You shouldn't be casting pointers that you pass to memset(3). It
accepts almost anything. That cast defeats the little type safety that
it has.
>
> 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);
>
>
Why two blanks here?
> }
> #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) {
Don't mix spaces and tabs.
Have a lovely night!
Alex
> //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;
> }
--
<https://www.alejandro-colomar.es/>
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