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[网络] socket select 问题 [复制链接]

liuchang8877

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发表于 2012-08-02 15:32 |只看该作者 |倒序浏览

本帖最后由 liuchang8877 于 2012-08-02 15:47 编辑

弱弱地问下， clien t /server 同时都用select ， client 向 server 发数据，为什么 server 端的 select 的返回值是0？？必须先从server 端 send 才能建立链接？
希望大牛们指教。

//server.c
#include<stdio.h>
#include<stdlib.h>
#include<unistd.h>
#include<sys/socket.h>
#include<arpa/inet.h>
#include<sys/types.h>
#include<errno.h>
#include<netdb.h>
#include<string.h>
#include<signal.h>
#include<stdarg.h> /*va_list*/
#define DIRECT_GET_CFG_PORT "21000"
#define PROTOCOL "tcp"
#define LINK_CHECK_TIMES 5
FILE *SafeLibErrorDest = NULL;
const char *SafeLibErrorLoc;
int SafeLibErrno = 0;
int server_init(const char *port,const char *proto);
void socketaddr_init(struct sockaddr_in *socketaddr);
int socketaddr_service(struct sockaddr_in *socketaddr,const char *service, const char *proto);
static int checkstring(const char *string);
void HandleError(int ecode, const char *const caller,
const char *fmt, ...);
int prototype(const char *proto);
int resolveproto(const char *proto);
int server_init(const char *port,const char *proto)
{
/*debug*/
printf("server_init,port:%s---proto:%s\n",port,proto);
struct sockaddr_in socketaddr;
int mastersock;
int trueval = 1;
socketaddr_init(&socketaddr);
socketaddr.sin_addr.s_addr = INADDR_ANY;
socketaddr_service(&socketaddr,port,proto);
mastersock = socket(PF_INET,prototype(proto),resolveproto(proto));
if(mastersock < 0){
HandleError(errno,"serverinit","counldn't create socket");
return -1;
}
setsockopt(mastersock,SOL_SOCKET,SO_REUSEADDR,&trueval,sizeof(socklen_t));
if(bind(mastersock,(struct sockaddr*)&socketaddr,sizeof(socketaddr)) < 0){
HandleError(errno,"serverinit","couldn't create socket");
return -1;
}
if(prototype(proto) == SOCK_STREAM){
if(listen(mastersock,5) < 0){
HandleError(errno,"serverinit","listen on port %d failed",port);
return -1;
}
}
else if(prototype(proto) == SOCK_DGRAM){
int buf_size = 512 *1024;
setsockopt(mastersock,SOL_SOCKET,SO_RCVBUF,(char *)&buf_size,sizeof(int));
}
return mastersock;
}
void socketaddr_init(struct sockaddr_in *socketaddr)
{
memset(socketaddr,0,sizeof(struct sockaddr));
socketaddr->sin_family = AF_INET;
}
int socketaddr_service(struct sockaddr_in *socketaddr,const char *service, const char *proto)
{
struct servent *serviceaddr;
/*debug*/
printf("socketaddr_service,service:%s---proto:%s\n",service,proto);
if(strcmp(service,"0") ==0)
socketaddr->sin_port = 0;
else{
serviceaddr = getservbyname(service,proto);
if(serviceaddr){
socketaddr->sin_port = serviceaddr->s_port;
}else{
if(checkstring(service)){
HandleError(0,"socket_service","no lookup for %s/%s",service,proto);
return -1;
}
if(0 == (socketaddr->sin_port = htons((u_short)atoi(service)))){
HandleError(0,"socketaddr_service","numeric conversion failed");
return -1;
}
}
}
/*debug*/
printf("socketaddr_service:port:%d\n",socketaddr->sin_port);
return 0;
}
static int checkstring(const char *string)
{
unsigned int counter;
for(counter = 0; counter <strlen(string); counter++)
if(!isdigit(string[counter]))
return 1;
return 0;
}
void HandleError(int ecode, const char *const caller,
const char *fmt, ...) {
va_list fmtargs;
struct sigaction sastruct;
FILE *of = (SafeLibErrorDest) ? SafeLibErrorDest : stderr;
/* Safe these into global variables for any possible signal handler. */
SafeLibErrorLoc = caller;
SafeLibErrno = ecode;
/* Print the error message(s) */
va_start(fmtargs, fmt);
fprintf(of, "*** Error in %s: ", caller);
vfprintf(of, fmt, fmtargs);
va_end(fmtargs);
fprintf(of, "\n");
if (ecode) {
fprintf(of, "*** Error cause: %s\n", strerror(ecode));
}
/* Exit if no signal handler. Otherwise, raise a signal. */
sigaction(SIGUSR1, NULL, &sastruct);
if (sastruct.sa_handler != SIG_DFL)
{
raise(SIGUSR1);
}
// else
// {
// exit(254);
// }
}
int prototype(const char *proto)
{
if(0 == strcmp(proto,"tcp"))
return SOCK_STREAM;
if(0 == strcmp(proto,"udp"))
return SOCK_DGRAM;
return -1;
}
int resolveproto(const char *proto)
{
struct protoent *protocol;
protocol = getprotobyname(proto);
if (!protocol)
{
HandleError(0, "resolveproto", "getprotobyname failed for %s", proto);
return -1;
}
return protocol->p_proto;
}
int main(void)
{
int mastersock;
int workersock;
struct sockaddr_in socketaddr;
int addrlen;
int nfds = 0;
fd_set orig_fdset,fdset;
int selectVal;
char logmsg[256];
struct timeval timeOut, tvCurr, tvLimit;
char BUF[256];
mastersock = server_init(DIRECT_GET_CFG_PORT,PROTOCOL);
/*debug*/
printf("*****mastersock:%d\n",mastersock);
if(mastersock >= nfds)
nfds = mastersock + 1;
timeOut.tv_sec =LINK_CHECK_TIMES;
timeOut.tv_usec = 0;
FD_ZERO(&orig_fdset);
FD_SET(mastersock,&orig_fdset);
addrlen = sizeof(socketaddr);
/*debbug*/
printf("addrlen:%d\n",addrlen);
gettimeofday(&tvCurr,0);
tvLimit = tvCurr;
tvLimit.tv_sec += LINK_CHECK_TIMES;
while(1){
bcopy(&orig_fdset,&fdset,sizeof(orig_fdset));
timeOut.tv_sec = tvLimit.tv_sec - tvCurr.tv_sec;
timeOut.tv_usec = 0;
selectVal = select(nfds,&fdset,(fd_set *)0,(fd_set *)0,0);
/*debug*/
printf("selectVal:%d\n",selectVal);
if(selectVal > 0){
if(FD_ISSET(mastersock,&fdset)){
/*debug*/
printf("Under FD_ISSET\n");
workersock = accept(mastersock,(struct sockaddr *)&socketaddr,(socklen_t *)&addrlen);
//sprintf("Received connection from a client %s port %d,sock id %d",inet_ntoa(socketaddr.sin_addr),ntohs(socketaddr.sin_port),workersock);
/*debug*/
printf("worlersock:%d\n",workersock);
if(workersock >= 0){
printf("start to send card info !\r \n");
memset(BUF,'2',256);
//write(workersock,BUF,256);
/*debug*/
//printf("sockId:%d\n",workersock);
send(workersock,BUF,256,0);
//sleep(1);
int result = recv(workersock,BUF,256,0);
//(workersock,BUF,256);
printf("result:%d:,recv data:%s\n",result,BUF);
//close(workersock);
}
}
}else if(0 == selectVal){
printf("warning: select retun 0");
sleep(1);
}else{
printf("error:select return error");
sleep(1);
}
}
close(mastersock);
return 0;
}

复制代码

//client.c
#include<stdio.h>
#include<stdlib.h>
#include<unistd.h>
#include<string.h>
#include<sys/socket.h>
#include<sys/types.h>
#include<netinet/in.h> /*struct in_addr*/
#include<errno.h>
#include<time.h>
#include<sys/time.h>
#include<stdarg.h> /*va_list*/
#include<signal.h> /*sigaction*/
#include<arpa/inet.h>
#include<ctype.h>
#include<sys/ioctl.h>
#include<netdb.h>
#define SERVER_IP "192.168.141.135"
#define SERVER_PORT "21000"
#ifndef __cplusplus
typedef char bool;
#define true 1
#define TRUE 1
#define false 0
#define FALSE 0
#endif
typedef signed long long SInt64;
#define BUFSIZE 256
#define SEC 3
#define TIMEOUT 5
#define PROTO "tcp"
const char *SafeLibErrorLoc;
int SafeLibErrno = 0;
FILE *SafeLibErrorDest = NULL;
int safeclose(int fd);
void HandleError(int ecode, const char *const caller,const char *fmt,...);
int clientconnect(const char *host,const char *port, const char *proto);
int resolveproto(const char *proto);
SInt64 Milliseconds();
int prototype(const char *proto);
void socketaddr_init(struct sockaddr_in *socketaddr);
int socketaddr_service(struct sockaddr_in *socketaddr, const char *service, const char *proto);
int socketaddr_host(struct sockaddr_in *socketaddr, const char *host);
int server_init(const char *port, const char *proto);
static int checkstring(const char *string);
//主要部分
int main(void)
{
int sockId = -1;
int count = 0;
int status = 0;
int timeOutCount;
fd_set selectSet, oriSelectSet;
SInt64 sStart = 0;
SInt64 snow = 0;
SInt64 sRecvLen=0,sLastRecvLen=0;
struct timeval timeOut;
int selectRvalue;
int result;
char cefBuff[BUFSIZE];
float fSafeNumber=0.0;
while(1){
struct in_addr addr;
char* serverIpStr;
char* tmpPort;
bool bMultiCast = false;
bool isUDP = false;
char IPFirst[4] = {0};
long nIpFirst;
int initFlag = 1;
status = 0;
timeOutCount = 0;
char Proto[4] = PROTO;
if(sockId >= 0){
safeclose(sockId);
sockId = -1;
sleep(1);
}
//char *ip = SERVER_IP;
//初始化
//addr.s_addr = (in_addr_t)ip;
//strcpy(serverIpStr,inet_ntoa(addr));
//sprintf(tmpPort,"%d",(int)SERVER_PORT);
serverIpStr = SERVER_IP;
tmpPort = SERVER_PORT;
/*debug*/
printf("serverIpStr:%s\n",serverIpStr);
for(count = 0; count < 3; count++){
sockId = clientconnect(serverIpStr,tmpPort,Proto);
printf("sockId:%d\n",sockId);
if(sockId >= 0) break;
sleep(1);
}
/*debug*/
printf("out for count <3\n");
if(sockId < 0){
sprintf("fail, connect lve ip is %s,port id %s,try times is %d\n NOW GO TO TRY_OTHER:",serverIpStr,tmpPort,count);
continue;
}
if(bMultiCast){
struct ip_mreq x;
unsigned long ipaddr_t = addr.s_addr;
memcpy(&x.imr_multiaddr.s_addr,&ipaddr_t,sizeof(ipaddr_t));
if(setsockopt(sockId,SOL_IP,IP_ADD_MEMBERSHIP,(char *)&x,sizeof(struct ip_mreq)) == -1){
printf("setsockopt error: %s\n",strerror(errno));
}
}
printf("success,connect lve ip:%s,port %s,sockId %d\n",serverIpStr,tmpPort,sockId);
FD_ZERO(&oriSelectSet);
FD_SET(sockId,&oriSelectSet);
sStart = Milliseconds();
while(initFlag){
memcpy(&selectSet,&oriSelectSet,sizeof(selectSet));
/*debug*/
printf("while(initFlag)\n");
timeOut.tv_sec =3 ;
timeOut.tv_usec = 0;
selectRvalue = select(sockId+1,&selectSet,NULL,NULL,&timeOut);
selectRvalue = 1;
if(selectRvalue > 0){
timeOutCount = 0;
printf("in it\n");
if(FD_ISSET(sockId,&selectSet)){
//关键处
int result = recv(sockId,cefBuff,BUFSIZE,0);
if(result){
printf("recv data:%s\n",cefBuff);
sleep(1);
memset(cefBuff,'1',BUFSIZE);
printf("send:%s\n",cefBuff);
int i;
while(1){
for(i = 0; i < 100; i++)
send(sockId,cefBuff,BUFSIZE,0);
}
}
}//监管
snow = Milliseconds();
if((snow-sStart) >= SEC*1000){
long ltotal = sRecvLen - sLastRecvLen;
ltotal *= 8;
if(ltotal <(long)fSafeNumber){
initFlag = 0;
sRecvLen = sLastRecvLen =0;
break;
}
sStart = snow;
sLastRecvLen = sRecvLen;
}
}else if(selectRvalue == 0){
//超时计数
sleep(2);
if(++timeOutCount >= TIMEOUT){
printf("time out\n");
initFlag = 0;
}
continue;
}else{
//系统出错
if(errno != EINTR)
printf("error sockId :%d",sockId);
initFlag = 0;
sleep(2);
continue;
}
}
}
printf("exit\n");
safeclose(sockId);
}
/*安全退出，关闭 sock*/
int safeclose(int fd)
{
int retval;
retval = close(fd);
if(fd == -1)
HandleError(errno,"close","Possible serious problem: close failed");
return retval;
}
/*错误处理*/
void HandleError(int ecode, const char *const caller,const char *fmt,...)
{
va_list fmtargs;
struct sigaction sastruct;
FILE *of = (SafeLibErrorDest)? SafeLibErrorDest: stderr;
SafeLibErrorLoc = caller;
SafeLibErrno = ecode;
va_start(fmtargs,fmt);
fprintf(of,"***Error in %s:",caller);
vfprintf(of,fmt,fmtargs);
va_end(fmtargs);
fprintf(of,"\n");
if(ecode){
fprintf(of,"*** Error cause: %s\n",strerror(ecode));
}
sigaction(SIGUSR1,NULL,&sastruct);
if(sastruct.sa_handler != SIG_DFL){
raise(SIGUSR1);
}
}
/*进行链接有超时机制*/
int clientconnect(const char *host,const char *port, const char *proto)
{
int sockid = -1;
int nProto = resolveproto(proto);
/*debug*/
printf("nProto:%d----port:%s,proto:%s\n",nProto,port,proto);
if(nProto == 17){
sockid = server_init(port ,proto);
}else{
unsigned long non_blocking = 1;
unsigned long blocking = 0;
struct sockaddr_in socketaddr;
socketaddr_init(&socketaddr);
socketaddr_service(&socketaddr,port,proto);
socketaddr_host(&socketaddr,host);
sockid = socket(PF_INET,prototype(proto),nProto);
if(sockid < 0){
return -1;
}
ioctl(sockid,FIONBIO,&non_blocking);
if( -1 == connect(sockid,(struct sockaddr *)&socketaddr,sizeof(struct sockaddr))){
struct timeval tv;
fd_set writefds;
int error;
//设置链接超时时间
tv.tv_sec = 3; //秒
tv.tv_usec = 0; //毫秒
FD_ZERO(&writefds);
FD_SET(sockid,&writefds);
if(select(sockid+1,NULL,&writefds,NULL,&tv) != 0){
if(FD_ISSET(sockid,&writefds)){
int len = sizeof(error);
//针对防火墙
if(getsockopt(sockid,SOL_SOCKET,SO_ERROR,(char *)&error,(unsigned int *)&len) < 0)
goto error_ret;
if(error != 0)
goto error_ret;
}else
goto error_ret; //超时或出错
}else
goto error_ret;
ioctl(sockid,FIONBIO,&blocking);
}
else{
error_ret:
safeclose(sockid);
return -1;
}
}
return sockid;
}
/*获得协议*/
int resolveproto(const char *proto)
{
struct protoent *protocol;
protocol = getprotobyname(proto);
/*debug*/
printf("resolveproto: proto:%s\n",proto);
if (!protocol)
{
HandleError(0, "resolveproto", "getprotobyname failed for %s", proto);
return -1;
}
return protocol->p_proto;
}
/*设置timeval*/
SInt64 Milliseconds()
{
struct timeval t;
struct timezone tz;
gettimeofday(&t, &tz);
SInt64 curTime;
curTime = t.tv_sec;
curTime *= 1000; // sec -> msec
curTime += t.tv_usec / 1000; // usec -> msec
return curTime;
}
/*判断是TCP或是UDP*/
int prototype(const char *proto)
{
if (strcmp(proto, "tcp") == 0){
/*debug*/
printf("return SOCK_STREAM\n");
return SOCK_STREAM;
}
if (strcmp(proto, "udp") == 0){
printf("return SOCK_DFRAM\n");
return SOCK_DGRAM;
}
return -1;
}
/*地址初始化*/
void socketaddr_init(struct sockaddr_in *socketaddr)
{
bzero((char *) socketaddr, sizeof(*socketaddr));
socketaddr->sin_family = AF_INET;
}
/*地址初始化*/
int socketaddr_service(struct sockaddr_in *socketaddr, const char *service, const char *proto)
{
struct servent *serviceaddr;
/* Need to allow numeric as well as textual data. */
/* 0: pass right through. */
if (strcmp(service, "0") == 0)
socketaddr->sin_port = 0;
else
{/* nonzero port */
serviceaddr = getservbyname(service, proto);
if (serviceaddr)
{
socketaddr->sin_port = serviceaddr->s_port;
}
else
{ /* name did not resolve, try number */
if (checkstring(service))
{ /* and it's a text name, fail. */
HandleError(0, "socketaddr_service", "no lookup for %s/%s", service, proto);
return -1;
}
if ((socketaddr->sin_port = htons((u_short)atoi(service))) == 0)
{
HandleError(0, "socketaddr_service", "numeric conversion failed");
return -1;
}
}
}
return 0;
}
/*服务器设置地址*/
int socketaddr_host(struct sockaddr_in *socketaddr, const char *host)
{
struct hostent *hostaddr;
hostaddr = gethostbyname(host);
if (!hostaddr)
{
HandleError(0, "socketaddr_host", "gethostbyname failed for %s", host);
return -1;
}
memcpy(&socketaddr->sin_addr, hostaddr->h_addr, hostaddr->h_length);
return 0;
}
/*服务端初始化*/
int server_init(const char *port, const char *proto)
{
struct sockaddr_in socketaddr;
int mastersock;
int trueval = 1;
/*debug*/
printf("server_init,port:%s---proto:%s\n",port,proto);
socketaddr_init(&socketaddr);
socketaddr.sin_addr.s_addr = INADDR_ANY;
socketaddr_service(&socketaddr, port, proto);
mastersock = socket(PF_INET, prototype(proto), resolveproto(proto));
if (mastersock < 0)
{
HandleError(errno, "serverinit", "couldn't create socket");
return -1;
}
setsockopt(mastersock,SOL_SOCKET,SO_REUSEADDR,&trueval,sizeof(socklen_t));
// if (bind(mastersock, (struct sockaddr *)&socketaddr, sizeof(socketaddr)) < 0)
{
HandleError(errno, "serverinit", "bind to port %s failed", port);
return -1;
}
//setsockopt(mastersock, SOL_SOCKET, 0, &trueval, sizeof(trueval));
if (prototype(proto) == SOCK_STREAM)
{
if (listen(mastersock, 5) < 0)
{
HandleError(errno, "serverinit", "listen on port %d failed", socketaddr.sin_port);
return -1;
}
}
else if (prototype(proto) == SOCK_DGRAM) {
int buf_size = 512 * 1024;
setsockopt(mastersock,SOL_SOCKET,SO_RCVBUF, (char *)&buf_size, sizeof(int));
}
return mastersock;
}
static int checkstring(const char *string)
{
unsigned int counter;
for (counter = 0; counter < strlen(string); counter++)
if (!(isdigit(string[counter])))
return 1;
return 0;
}

复制代码

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liuchang8877

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2楼 [报告]

发表于 2012-08-02 16:20 |只看该作者

为什么就没人回的帖子了？

实战分享：从技术角度谈机器学习入门| 【大话IT】RadonDB低门槛向MySQL集群下战书 | ChinaUnix打赏功能已上线！ | 新一代分布式关系型数据库RadonDB知多少？

liuchang8877

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3楼 [报告]

发表于 2012-08-02 16:39 |只看该作者

自己顶上去。希望有人看到

xiyoulaoyuanjia

小富即安

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4楼 [报告]

发表于 2012-08-02 17:03 |只看该作者

代码太长，问题说的不是很清楚~ 能简洁点不？

liuchang8877

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5楼 [报告]

发表于 2012-08-02 17:11 |只看该作者

回复 4# xiyoulaoyuanjia select 什么时候返回 >0 . ｍａｎ　里面说http://linux.die.net/man/2/select　是可用资源数，这个不太明白，能给说说？

Moon_Bird

丰衣足食

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6楼 [报告]

发表于 2012-08-02 20:50 |只看该作者

select返回值可简单的理解为阻塞监听的套接字事件集中做出响应的数目

没看代码...................太多了 .....
---"client 向 server 发数据，为什么 server 端的 select 的返回值是0"
服务器端使用select监听该新建连接socket的可读事件没有..

cxchao802

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7楼 [报告]

发表于 2012-08-02 23:06 |只看该作者

你的select（）的timeout设为0，也就是不等待直接返回，没检测到有连接请求的时候，当然返回0了，既然要实现非阻塞的读写，这个值要么是NULL，要么就设一个非0超时。还有你这个select根本没什么意义，你可以把read，write和accept，send，recv都监听，这样才能突出select的用处。