本帖最后由 lrser 于 2016-6-22 12:02 编辑

我在F407开发板上想用SELECT函数实现并发的功能，也就是开发板当服务器连接多个TCP客户端。可是不管怎样都只能连接一个客户端，第一个连上后，后面的在网络助手中连接时显示1035错误。
首先是用lwip_comm_init()和lwip_comm_dhcp_creat()初始化网络获得IP后运行下列chargen_init（）代码：

[mw_shl_code=applescript,true]/** @file
*
* chargen server for lwip
*/
/*
* Copyright (c) 2003 NBS Card Technology, Paramus, NJ.
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without modification,
* are permitted provided that the following conditions are met:
*
* 1. Redistributions of source code must retain the above copyright notice,
* this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright notice,
* this list of conditions and the following disclaimer in the documentation
* and/or other materials provided with the distribution.
* 3. The name of the author may not be used to endorse or promote products
* derived from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED
* WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
* MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT
* SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
* EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT
* OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING
* IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY
* OF SUCH DAMAGE.
*
* This file is part of the lwIP TCP/IP stack.
*
* Author: David Haas <dhaas@alum.rpi.edu>
*
* Purpose: chargen server for testing and demonstration purposes
*
* This file implements a nice example of handling multiple tcp sockets in a
* server environment. Just call chargen_init() from your application after
* you have initialized lwip and added your network interfaces. Change the
* MAX_SERV option to increase or decrease the number of sessions supported.
*
* chargen will jam as much data as possible into the output socket, so it
* will take up a lot of CPU time. Therefore it will be a good idea to run it
* as the lowest possible priority (just ahead of any idle task).
*
* This is also a good example of how to support multiple sessions in an
* embedded system where you might not have fork().
*/

#include "lwip/opt.h"
#include "lwip/sys.h"
#include "lwip/sockets.h"
#include "lwip/mem.h"

#include <string.h>

#include "chargen.h"

#if LWIP_SOCKET

#define MAX_SERV 5 /* Maximum number of chargen services. Don't need too many */
#define CHARGEN_THREAD_NAME "chargen"
#define CHARGEN_PRIORITY 254 /* Really low priority */
#define CHARGEN_THREAD_STACKSIZE 0
#define SEND_SIZE TCP_SNDLOWAT /* If we only send this much, then when select
says we can send, we know we won't block */
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);

/**************************************************************
* 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;
LWIP_UNUSED_ARG(arg);

/* First acquire our socket for listening for connections */
listenfd = socket(AF_INET, SOCK_STREAM, 0);

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 = PP_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 *)mem_malloc(sizeof(struct charcb));
if (p_charcb)
{
p_charcb->socket = accept(listenfd,
(struct sockaddr *) &p_charcb->cliaddr,
&p_charcb->clilen);
if (p_charcb->socket < 0)
mem_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)
close(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 = setchar;
if (++setchar == 0x7f)
setchar = 0x21;
}
line = 0;
strcat(line, " ");
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 */
close(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;
}
}
mem_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;
}
Printf("recv data len = %d ", readcount);
return 0;
}


/**************************************************************
* void chargen_init(void)
*
* This function initializes the chargen service. This function
* may only be called either before or after tasking has started.
**************************************************************/
void chargen_init(void)
{
sys_thread_new( CHARGEN_THREAD_NAME, chargen_thread, 0, CHARGEN_THREAD_STACKSIZE, TCPIP_THREAD_PRIO+1);

}

#endif /* LWIP_SOCKET */
[/mw_shl_code]


麻烦帮我看看，好多天了都搞不好。
不知原子大哥什么时候能出这方面的例程啊？