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| This page describes step-by-step how to play with TCP dumping and restoring. | | This page describes step-by-step how to play with TCP dumping and restoring. |
| + | |
| + | __TOC__ |
| | | |
| == Compile and run simple TCP client and server == | | == Compile and run simple TCP client and server == |
| The below program is a simple echo server and a client, that pings server with increasing numbers once a second. In this howto we will dump and restore the client part. | | The below program is a simple echo server and a client, that pings server with increasing numbers once a second. In this howto we will dump and restore the client part. |
− | <pre>
| + | {| class="mw-collapsible mw-collapsed wikitable" |
− | #include <sys/socket.h>
| + | ! <code>tcp-howto.c</code> |
− | #include <linux/types.h>
| + | |- |
− | #include <sys/types.h>
| + | | {{:Simple_TCP_pair/tcp-howto.c}} |
− | #include <arpa/inet.h>
| + | |} |
− | #include <unistd.h>
| |
− | #include <string.h>
| |
− | #include <stdlib.h>
| |
− | #include <stdio.h>
| |
− | #include <signal.h>
| |
− | | |
− | static int serve_new_conn(int sk)
| |
− | {
| |
− | int rd, wr;
| |
− | char buf[1024];
| |
− | | |
− | printf("New connection\n");
| |
− | | |
− | while (1) {
| |
− | rd = read(sk, buf, sizeof(buf));
| |
− | if (!rd)
| |
− | break;
| |
− | | |
− | if (rd < 0) {
| |
− | perror("Can't read socket");
| |
− | return 1;
| |
− | }
| |
− | | |
− | wr = 0;
| |
− | while (wr < rd) {
| |
− | int w;
| |
− | | |
− | w = write(sk, buf + wr, rd - wr);
| |
− | if (w <= 0) {
| |
− | perror("Can't write socket");
| |
− | return 1;
| |
− | }
| |
− | | |
− | wr += w;
| |
− | }
| |
− | }
| |
− | | |
− | printf("Done\n");
| |
− | return 0;
| |
− | }
| |
− | | |
− | static int main_srv(int argc, char **argv)
| |
− | { | |
− | int sk, port, ret;
| |
− | struct sockaddr_in addr;
| |
− | | |
− | /*
| |
− | * Let kids die themselves
| |
− | */
| |
− | | |
− | signal(SIGCHLD, SIG_IGN);
| |
− | | |
− | sk = socket(PF_INET, SOCK_STREAM, IPPROTO_TCP);
| |
− | if (sk < 0) {
| |
− | perror("Can't create socket");
| |
− | return -1;
| |
− | }
| |
− | | |
− | port = atoi(argv[1]);
| |
− | memset(&addr, 0, sizeof(addr));
| |
− | addr.sin_family = AF_INET;
| |
− | addr.sin_addr.s_addr = htonl(INADDR_ANY);
| |
− | addr.sin_port = htons(port);
| |
− | | |
− | printf("Binding to port %d\n", port);
| |
− | | |
− | ret = bind(sk, (struct sockaddr *)&addr, sizeof(addr));
| |
− | if (ret < 0) {
| |
− | perror("Can't bind socket");
| |
− | return -1;
| |
− | }
| |
− | | |
− | ret = listen(sk, 16);
| |
− | if (ret < 0) {
| |
− | perror("Can't put sock to listen");
| |
− | return -1;
| |
− | }
| |
| | | |
− | printf("Waiting for connections\n");
| + | Compile it and run the server: |
− | while (1) {
| |
− | int ask, pid;
| |
| | | |
− | ask = accept(sk, NULL, NULL);
| + | # ./tcp-howto <some-port> |
− | if (ask < 0) {
| |
− | perror("Can't accept new conn");
| |
− | return -1;
| |
− | }
| |
| | | |
− | pid = fork();
| + | On another terminal (for better output readability) run the client: |
− | if (pid < 0) {
| |
− | perror("Can't fork");
| |
− | return -1;
| |
− | }
| |
| | | |
− | if (pid > 0)
| + | # ./tcp-howto 127.0.0.1 <some-port> |
− | close(ask);
| |
− | else {
| |
− | close(sk);
| |
− | ret = serve_new_conn(ask);
| |
− | exit(ret);
| |
− | }
| |
− | }
| |
− | }
| |
− | | |
− | static int main_cl(int argc, char **argv)
| |
− | {
| |
− | int sk, port, ret, val = 1, rval;
| |
− | struct sockaddr_in addr;
| |
− | | |
− | sk = socket(PF_INET, SOCK_STREAM, IPPROTO_TCP);
| |
− | if (sk < 0) {
| |
− | perror("Can't create socket");
| |
− | return -1;
| |
− | }
| |
− | | |
− | port = atoi(argv[2]);
| |
− | printf("Connecting to %s:%d\n", argv[1], port);
| |
− | memset(&addr, 0, sizeof(addr));
| |
− | addr.sin_family = AF_INET;
| |
− | ret = inet_aton(argv[1], &addr.sin_addr);
| |
− | if (ret < 0) {
| |
− | perror("Can't convert addr");
| |
− | return -1;
| |
− | }
| |
− | addr.sin_port = htons(port);
| |
− | | |
− | ret = connect(sk, (struct sockaddr *)&addr, sizeof(addr));
| |
− | if (ret < 0) {
| |
− | perror("Can't connect");
| |
− | return -1;
| |
− | }
| |
− | | |
− | while (1) {
| |
− | write(sk, &val, sizeof(val));
| |
− | rval = -1;
| |
− | read(sk, &rval, sizeof(rval));
| |
− | printf("PP %d -> %d\n", val, rval);
| |
− | sleep(2);
| |
− | val++;
| |
− | }
| |
− | }
| |
− | | |
− | int main(int argc, char **argv)
| |
− | {
| |
− | if (argc == 2)
| |
− | return main_srv(argc, argv);
| |
− | else if (argc == 3)
| |
− | return main_cl(argc, argv);
| |
− | | |
− | printf("Bad usage\n");
| |
− | return 1;
| |
− | }
| |
− | </pre>
| |
− | | |
− | So compile it and run server
| |
− | <pre>
| |
− | # ./tcp-howto <some-port>
| |
− | </pre>
| |
− | and on another terminal (for better output readability) -- the client
| |
− | <pre>
| |
− | # ./tcp-howto 127.0.0.1 <some-port> | |
− | </pre>
| |
| | | |
| == Try to dump the client == | | == Try to dump the client == |
| Create a directory for images (<code>img-dir/</code> below) and dump the client | | Create a directory for images (<code>img-dir/</code> below) and dump the client |
| <pre> | | <pre> |
− | # crtools dump --tree <tcp-howto-client-pid> --images-dir img-dir/ -v 4 -o dump.log --shell-job --tcp-established | + | # criu dump --tree <tcp-howto-client-pid> --images-dir img-dir/ -v4 -o dump.log --shell-job --tcp-established |
| </pre> | | </pre> |
| | | |
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| It's done like this | | It's done like this |
| <pre> | | <pre> |
− | # crtools restore --tree <tcp-howto-client-pid> --images-dir img-dir/ -v 4 -o rst.log --shell-job --tcp-established | + | # criu restore --images-dir img-dir/ -v4 -o rst.log --shell-job --tcp-established |
| </pre> | | </pre> |
| | | |
− | That's it. After this in the terminal you launched crtools from you should see the contunuing output of the tcp client. | + | That's it. After this in the terminal you launched criu from you should see the continuing output of the tcp client. |
| + | |
| + | == See also == |
| + | |
| + | * [[TCP connection]] |
| + | |
| + | [[Category:HOWTO]] |
| + | [[Category:Sockets]] |