January 2015 – 我的经验分享

1.需要包含头文件netinet/in.h，IPPROTO_TCP、IPPROTO_IPV6等定义在这个头文件中。

2.exit定义在stdlib.h中。

3.需要定义sock_str_flag、sock_str_int、sock_str_linger和sock_str_timeval。

4.理论上每个sock_opts都应该用ifdef进行判断，但是考虑到centos本身就没有sctp相关选项，所以直接屏蔽。

checkopts.cpp，github网址：https://github.com/siukwan/unix/tree/master/7thChapterSocketOpt
代码如下：

[c language=”++”]
/*
* sock_opts定义应该每一个都有if else的判断
* 实际情况是没有sctp的选项，于是直接屏蔽
*
*/
#include<stdio.h>
#include<iostream>

#include<netinet/tcp.h>
#include<netinet/in.h>
#include<sys/socket.h>
#include <stdarg.h>
#include<syslog.h>
#include<errno.h>
#include<string.h>
#include<stdlib.h>
#include<unistd.h>

using namespace std;
#define MAXLINE 1024
int daemon_proc;

void err_ret(const char *fmt,…);
void err_quit(const char *fmt,…);
union val{
int i_val;
long l_val;
linger linger_val;
timeval timeval_val;
}sock_val;

static char *sock_str_flag(val *,int);
static char *sock_str_int(val*,int);
static char *sock_str_linger(val* ,int);
static char *sock_str_timeval(val*,int);

struct opts{
const char *opt_str;
int opt_level;
int opt_name;
char *(*opt_val_str)(val *,int);
}sock_opts[]={
{"SO_BROADCAST", SOL_SOCKET, SO_BROADCAST, sock_str_flag },
{"SO_DEBUG", SOL_SOCKET, SO_DEBUG, sock_str_flag },
{"SO_DONTROUTE", SOL_SOCKET, SO_DONTROUTE, sock_str_flag },
{"SO_ERROR", SOL_SOCKET, SO_ERROR, sock_str_int },
{"SO_KEEPALIVE", SOL_SOCKET, SO_KEEPALIVE, sock_str_flag },
{"SO_LINGER", SOL_SOCKET, SO_LINGER, sock_str_linger },
{"SO_OOBINLINE", SOL_SOCKET, SO_OOBINLINE, sock_str_flag },
{"SO_RCVBUF", SOL_SOCKET, SO_RCVBUF, sock_str_int },
{"SO_SNDBUF", SOL_SOCKET, SO_SNDBUF, sock_str_int },
{"SO_RCVLOWAT", SOL_SOCKET, SO_RCVLOWAT, sock_str_int },
{"SO_SNDLOWAT", SOL_SOCKET, SO_SNDLOWAT, sock_str_int },
{"SO_RCVTIMEO", SOL_SOCKET, SO_RCVTIMEO, sock_str_timeval },
{"SO_SNDTIMEO", SOL_SOCKET, SO_SNDTIMEO, sock_str_timeval },
{"SO_REUSEADDR", SOL_SOCKET, SO_REUSEADDR, sock_str_flag },

#ifdef SO_REUSEPORT
{"SO_REUSEPORT", SOL_SOCKET, SO_REUSEPORT, sock_str_flag },
#else
{"SO_REUSEPORT", 0, 0, NULL },
#endif
{"SO_TYPE", SOL_SOCKET, SO_TYPE, sock_str_int },

#ifdef SO_USELOOPBACK
{"SO_USELOOPBACK", SOL_SOCKET, SO_USELOOPBACK, sock_str_flag },
#else
{"SO_USELOOPBACK", 0, 0, NULL },
#endif

#ifdef IP_TOS
{"IP_TOS", IPPROTO_IP, IP_TOS, sock_str_int },
#else
{"IP_TOS", 0, 0, NULL },
#endif

#ifdef IP_TTL
{"IP_TTL", IPPROTO_IP, IP_TTL, sock_str_int },
#else
{"IP_TTL", 0, 0, NULL },
#endif

#ifdef IPV6_DONTFRAG
{"IPV6_DONTFRAG", IPPROTO_IPV6, IPV6_DONTFRAG, sock_str_flag },
#else
{"IPV6_DONTFRAG", 0, 0, NULL },
#endif

{"IPV6_UNICAST_HOPS", IPPROTO_IPV6, IPV6_UNICAST_HOPS, sock_str_int },
{"IPV6_V6ONLY", IPPROTO_IPV6, IPV6_V6ONLY, sock_str_flag },
{"TCP_MAXSEG", IPPROTO_TCP, TCP_MAXSEG, sock_str_int },
{"TCP_NODELAY", IPPROTO_SCTP, TCP_NODELAY, sock_str_flag },
// {"SCTP_AUTOCLOSE", IPPROTO_TCP, SCTP_AUTOCLOSE, sock_str_int },
// {"SCTP_MAXBURST", IPPROTO_SCTP, SCTP_MAXBURST, sock_str_int },
// {"SCTP_MAXSEG", IPPROTO_SCTP, SCTP_MAXSEG, sock_str_int },
// {"SCTP_NODELAY", IPPROTO_SCTP, SCTP_NODELAY, sock_str_flag },
{NULL, 0, 0, NULL },
};

int main(int argc,char **argv)
{
int fd;
socklen_t len;
opts *ptr;

for(ptr=sock_opts;ptr->opt_str !=NULL;ptr++)
{
printf("%s:",ptr->opt_str);

if(ptr->opt_val_str == NULL)
printf("(undefined)\n");
else
{
switch(ptr->opt_level)
{
case SOL_SOCKET:
case IPPROTO_IP:
case IPPROTO_TCP:
fd = socket(AF_INET,SOCK_STREAM,0);
break;
default:
err_quit("Can’t create fd for level %d\n",ptr->opt_level);
}

len = sizeof(val);
if(getsockopt(fd,ptr->opt_level,ptr->opt_name,&sock_val,&len) == -1)
err_ret("getsockopt error");
else
printf("default = %s\n",(*ptr->opt_val_str)(&sock_val,len));

close(fd);

}

}
}

//记录日志
void err_doit(int errnoflag, int level ,const char *fmt, va_list ap)
{
int errno_save,n;
char buf[MAXLINE+1];

errno_save = errno;
#ifdef HAVE_VSNPRINTF
vsnprintf(buf,MAXLINE, fmt , ap);
#else
vsprintf(buf,fmt,ap);
#endif
n=strlen(buf);
if(errnoflag)
snprintf(buf+n,MAXLINE-n,": %s",strerror(errno_save));
strcat(buf,"\n");

if(daemon_proc)
{
syslog(level,buf);
}
else
{
fflush(stdout);
fputs(buf,stderr);
fflush(stderr);
}
}
//错误退出，和上面一样
void err_quit(const char *fmt,…)
{
va_list ap;
va_start(ap,fmt);
err_doit(0,LOG_ERR, fmt,ap);
va_end(ap);
exit(1);
}
void err_ret(const char *fmt,…)
{
va_list ap;
va_start(ap,fmt);
err_doit(1,LOG_INFO,fmt,ap);
va_end(ap);
return ;
}

static char strres[128];

static char *
sock_str_flag(union val *ptr, int len)
{
/* *INDENT-OFF* */
if (len != sizeof(int))
snprintf(strres, sizeof(strres), "size (%d) not sizeof(int)", len);
else
snprintf(strres, sizeof(strres),
"%s", (ptr->i_val == 0) ? "off" : "on");
return(strres);
/* *INDENT-ON* */
}
/* end checkopts3 */

static char *
sock_str_int(union val *ptr, int len)
{
if (len != sizeof(int))
snprintf(strres, sizeof(strres), "size (%d) not sizeof(int)", len);
else
snprintf(strres, sizeof(strres), "%d", ptr->i_val);
return(strres);
}

static char *
sock_str_linger(union val *ptr, int len)
{
struct linger *lptr = &ptr->linger_val;

if (len != sizeof(struct linger))
snprintf(strres, sizeof(strres),
"size (%d) not sizeof(struct linger)", len);
else
snprintf(strres, sizeof(strres), "l_onoff = %d, l_linger = %d",
lptr->l_onoff, lptr->l_linger);
return(strres);
}

static char *
sock_str_timeval(union val *ptr, int len)
{
struct timeval *tvptr = &ptr->timeval_val;

if (len != sizeof(struct timeval))
snprintf(strres, sizeof(strres),
"size (%d) not sizeof(struct timeval)", len);
else
snprintf(strres, sizeof(strres), "%d sec, %d usec",
tvptr->tv_sec, tvptr->tv_usec);
return(strres);
}

[/c]

Month: January 2015

解决应用程序无法正常启动(0xc000007b)问题

unix网络编程：检查选项是否受支持并获取默认值