rt-thread-official/examples/network/chargen.c

/*
 * Copyright (c) 2006-2021, RT-Thread Development Team
 *
 * SPDX-License-Identifier: Apache-2.0
 *
 * Change Logs:
 * Date           Author       Notes
 */

#include <rtthread.h>
#include <sys/socket.h>

#ifdef SAL_USING_POSIX
#include <sys/select.h> // only dfs_net
#include <dfs_posix.h>
#else
#define read        lwip_read
#define write       lwip_write
#endif /* SAL_USING_POSIX */

#include "netdb.h"

#define MAX_SERV                 32         /* Maximum number of chargen services. Don't need too many */
#define CHARGEN_THREAD_NAME      "chargen"
#if RT_THREAD_PRIORITY_MAX == 32
#define CHARGEN_PRIORITY         20        /* Really low priority */
#else
#define CHARGEN_PRIORITY         200       /* Really low priority */
#endif
#define CHARGEN_THREAD_STACKSIZE 1024
struct charcb
{
    struct charcb *next;
    int socket;
    struct sockaddr_in cliaddr;
    socklen_t clilen;
    char nextchar;
};

static struct charcb *charcb_list = 0;
static int do_read(struct charcb *p_charcb);
static void close_chargen(struct charcb *p_charcb);
extern int select(int nfds, fd_set *readfds, fd_set *writefds, fd_set *exceptfds, struct timeval *timeout);

/**************************************************************
 * void chargen_thread(void *arg)
 *
 * chargen task. This server will wait for connections on well
 * known TCP port number: 19. For every connection, the server will
 * write as much data as possible to the tcp port.
 **************************************************************/
static void chargen_thread(void *arg)
{
    int listenfd;
    struct sockaddr_in chargen_saddr;
    fd_set readset;
    fd_set writeset;
    int i, maxfdp1;
    struct charcb *p_charcb;

    /* First acquire our socket for listening for connections */
    listenfd = socket(AF_INET, SOCK_STREAM, IPPROTO_TCP);
    LWIP_ASSERT("chargen_thread(): Socket create failed.", listenfd >= 0);
    memset(&chargen_saddr, 0, sizeof(chargen_saddr));
    chargen_saddr.sin_family = AF_INET;
    chargen_saddr.sin_addr.s_addr = htonl(INADDR_ANY);
    chargen_saddr.sin_port = htons(19);     // Chargen server port

    if (bind(listenfd, (struct sockaddr *) &chargen_saddr, sizeof(chargen_saddr)) == -1)
        LWIP_ASSERT("chargen_thread(): Socket bind failed.", 0);

    /* Put socket into listening mode */
    if (listen(listenfd, MAX_SERV) == -1)
        LWIP_ASSERT("chargen_thread(): Listen failed.", 0);


    /* Wait forever for network input: This could be connections or data */
    for (;;)
    {
        maxfdp1 = listenfd + 1;

        /* Determine what sockets need to be in readset */
        FD_ZERO(&readset);
        FD_ZERO(&writeset);
        FD_SET(listenfd, &readset);
        for (p_charcb = charcb_list; p_charcb; p_charcb = p_charcb->next)
        {
            if (maxfdp1 < p_charcb->socket + 1)
                maxfdp1 = p_charcb->socket + 1;
            FD_SET(p_charcb->socket, &readset);
            FD_SET(p_charcb->socket, &writeset);
        }

        /* Wait for data or a new connection */
        i = select(maxfdp1, &readset, &writeset, 0, 0);

        if (i == 0) continue;

        /* At least one descriptor is ready */
        if (FD_ISSET(listenfd, &readset))
        {
            /* We have a new connection request!!! */
            /* Lets create a new control block */
            p_charcb = (struct charcb *)rt_calloc(1, sizeof(struct charcb));
            if (p_charcb)
            {
                p_charcb->socket = accept(listenfd,
                                          (struct sockaddr *) &p_charcb->cliaddr,
                                          &p_charcb->clilen);
                if (p_charcb->socket < 0)
                    rt_free(p_charcb);
                else
                {
                    /* Keep this tecb in our list */
                    p_charcb->next = charcb_list;
                    charcb_list = p_charcb;
                    p_charcb->nextchar = 0x21;
                }
            }
            else
            {
                /* No memory to accept connection. Just accept and then close */
                int sock;
                struct sockaddr cliaddr;
                socklen_t clilen;

                sock = accept(listenfd, &cliaddr, &clilen);
                if (sock >= 0)
                    closesocket(sock);
            }
        }

        /* Go through list of connected clients and process data */
        for (p_charcb = charcb_list; p_charcb; p_charcb = p_charcb->next)
        {
            if (FD_ISSET(p_charcb->socket, &readset))
            {
                /* This socket is ready for reading. This could be because someone typed
                 * some characters or it could be because the socket is now closed. Try reading
                 * some data to see. */
                if (do_read(p_charcb) < 0)
                    break;
            }

            if (FD_ISSET(p_charcb->socket, &writeset))
            {
                char line[80];
                char setchar = p_charcb->nextchar;

                for (i = 0; i < 59; i++)
                {
                    line[i] = setchar;
                    if (++setchar == 0x7f)
                        setchar = 0x21;
                }

                line[i] = 0;
                strcat(line, "\n\r");
                if (write(p_charcb->socket, line, strlen(line)) < 0)
                {
                    close_chargen(p_charcb);
                    break;
                }

                if (++p_charcb->nextchar == 0x7f)
                    p_charcb->nextchar = 0x21;
            }
        }
    }
}

/**************************************************************
 * void close_chargen(struct charcb *p_charcb)
 *
 * Close the socket and remove this charcb from the list.
 **************************************************************/
static void close_chargen(struct charcb *p_charcb)
{
    struct charcb *p_search_charcb;

    /* Either an error or tcp connection closed on other
     * end. Close here */
    closesocket(p_charcb->socket);

    /* Free charcb */
    if (charcb_list == p_charcb)
        charcb_list = p_charcb->next;
    else
        for (p_search_charcb = charcb_list; p_search_charcb; p_search_charcb = p_search_charcb->next)
        {
            if (p_search_charcb->next == p_charcb)
            {
                p_search_charcb->next = p_charcb->next;
                break;
            }
        }

    rt_free(p_charcb);
}

/**************************************************************
 * void do_read(struct charcb *p_charcb)
 *
 * Socket definitely is ready for reading. Read a buffer from the socket and
 * discard the data.  If no data is read, then the socket is closed and the
 * charcb is removed from the list and freed.
 **************************************************************/
static int do_read(struct charcb *p_charcb)
{
    char buffer[80];
    int readcount;

    /* Read some data */
    readcount = read(p_charcb->socket, &buffer, 80);
    if (readcount <= 0)
    {
        close_chargen(p_charcb);
        return -1;
    }
    return 0;
}

void chargen_init(void)
{
    rt_thread_t chargen;

    chargen = rt_thread_create(CHARGEN_THREAD_NAME,
                               chargen_thread, RT_NULL,
                               CHARGEN_THREAD_STACKSIZE,
                               CHARGEN_PRIORITY, 5);
    if (chargen != RT_NULL) rt_thread_startup(chargen);
}
#ifdef RT_USING_FINSH
#include <finsh.h>
void chargen()
{
    chargen_init();
}
FINSH_FUNCTION_EXPORT(chargen, start chargen server);
#endif