// TCP的socket連接示例
// Saturday,?4.?March?2006,?05:35:49
/**/ /*
Socket,?TCP,?異步?
tp://www.zeali.net/blog/entry.php?id=13

用C實(shí)現(xiàn)的TCP?socket連接/讀/寫操作。采用fcntl設(shè)置非阻塞式連接以實(shí)現(xiàn)connect超時(shí)處理；采用select方法來設(shè)置socket讀寫超時(shí)。此示例可被編譯運(yùn)行于Windows/unix系統(tǒng)。

源文件connector.c

原來的代碼在windows下編譯不通過，今天qzj問起才發(fā)現(xiàn)。因?yàn)榧恿水惒降奶幚恚瑳]有對(duì)這部分代碼進(jìn)行兼容性處理。本著做學(xué)問一絲不茍嘀精神，重新修改了一下源代碼。以下代碼在VC++6和linux下編譯執(zhí)行通過?

同時(shí)mark幾個(gè)有用的url:

http://people.web.psi.ch/rohrer_u/sample1.htm ?Demo?program?for?remote?CAMAC?access?via?TCP/IP

http://www.lsword.net/code/list.asp?id=1383 ?將Socket應(yīng)用程序從Unix向Windows移植中應(yīng)注意的幾點(diǎn)問題
*/
/**/ /*
*?on?Unix:
*?cc?-c?connector.c
*?cc?-o?connector?connector.o
*
*?on?Windows?NT:
*?open?connector.c?in?Visual?Studio
*?press?'F7'?to?link?--?a?project?to?be?created
*?add?wsock32.lib?to?the?link?section?under?project?setting
*?press?'F7'?again
*
*?running:
*?type?'connector'?for?usage
*/

#include? < stdio.h >
#include? < stdlib.h >
#include? < string .h >
#include? < stdarg.h >
#include? < errno.h >
#include? < fcntl.h >
#ifdef?WIN32
#include? < winsock2.h >
#else
#include? < unistd.h >
#include? < sys / types.h >
#include? < sys / socket.h >
#include? < sys / ioctl.h >
#include? < netinet / in .h >
#include? < arpa / inet.h >
#include? < netdb.h >
#endif

#ifndef?INADDR_NONE
#define ?INADDR_NONE?0xffffffff
#endif
#define ?MAX_STRING_LEN?1024
#define ?BUFSIZE?2048

#ifndef?WIN32
#define ?SOCKET?int
#else
#define ?errno?WSAGetLastError()
#define ?close(a)?closesocket(a)
#define ?write(a,?b,?c)?send(a,?b,?c,?0)
#define ?read(a,?b,?c)?recv(a,?b,?c,?0)
#endif

char ?buf[BUFSIZE];

static ? char ?i_host[MAX_STRING_LEN];? /**/ /* ?site?name? */
static ? char ?i_port[MAX_STRING_LEN];? /**/ /* ?port?number? */

void ?err_doit( int ?errnoflag,? const ? char ? * fmt,?va_list?ap);
void ?err_quit( const ? char ? * fmt,?);
int ?tcp_connect( const ? char ? * host,? const ?unsigned? short ?port);
void ?print_usage();

// xnet_select?x?defines
#define ?READ_STATUS?0
#define ?WRITE_STATUS?1
#define ?EXCPT_STATUS?2

/**/ /*
s?-?SOCKET
sec?-?timeout?seconds
usec?-?timeout?microseconds
x?-?select?status
*/
SOCKET?xnet_select(SOCKET?s,? int ?sec,? int ?usec,? short ?x)
{
int ?st? = ?errno;
struct ?timeval?to;
fd_set?fs;
to.tv_sec? = ?sec;
to.tv_usec? = ?usec;
FD_ZERO( & fs);
FD_SET(s,? & fs);
switch (x) {
case ?READ_STATUS:
st? = ?select(s + 1 ,? & fs,? 0 ,? 0 ,? & to);
break ;
case ?WRITE_STATUS:
st? = ?select(s + 1 ,? 0 ,? & fs,? 0 ,? & to);
break ;
case ?EXCPT_STATUS:
st? = ?select(s + 1 ,? 0 ,? 0 ,? & fs,? & to);
break ;
}
return (st);
}

int ?tcp_connect( const ? char ? * host,? const ?unsigned? short ?port)
{
unsigned? long ?non_blocking? = ? 1 ;
unsigned? long ?blocking? = ? 0 ;
int ?ret? = ? 0 ;
char ? * ?transport? = ? " tcp " ;
struct ?hostent? * phe;? /**/ /* ?pointer?to?host?information?entry? */
struct ?protoent? * ppe;? /**/ /* ?pointer?to?protocol?information?entry */
struct ?sockaddr_in?sin;? /**/ /* ?an?Internet?endpoint?address? */
SOCKET?s;? /**/ /* ?socket?descriptor?and?socket?type? */
int ?error;

#ifdef?WIN32
{
WORD?wVersionRequested;
WSADATA?wsaData;
int ?err;

wVersionRequested? = ?MAKEWORD(? 2 ,? 0 ?);

err? = ?WSAStartup(?wVersionRequested,? & wsaData?);
if ?(?err? != ? 0 ?)? {
/**/ /* ?Tell?the?user?that?we?couldn't?find?a?usable? */
/**/ /* ?WinSock?DLL.? */
printf( " can't?initialize?socket?library\n " );
exit( 0 );
}
}
#endif ?

memset( & sin,? 0 ,? sizeof (sin));
sin.sin_family? = ?AF_INET;

if ?((sin.sin_port? = ?htons(port))? == ? 0 )
err_quit( " invalid?port?\ " % d\ " \n " ,?port);

/**/ /* ?Map?host?name?to?IP?address,?allowing?for?dotted?decimal? */
if ?(?phe? = ?gethostbyname(host)?)
memcpy( & sin.sin_addr,?phe -> h_addr,?phe -> h_length);
else ? if ?(?(sin.sin_addr.s_addr? = ?inet_addr(host))? == ?INADDR_NONE?)
err_quit( " can't?get?\ " % s\ " ?host?entry\n " ,?host);

/**/ /* ?Map?transport?protocol?name?to?protocol?number? */
if ?(?(ppe? = ?getprotobyname(transport))? == ? 0 )
err_quit( " can't?get?\ " % s\ " ?protocol?entry\n " ,?transport);

/**/ /* ?Allocate?a?socket? */
s? = ?socket(PF_INET,?SOCK_STREAM,?ppe -> p_proto);
if ?(s? < ? 0 )
err_quit( " can't?create?socket:?%s\n " ,?strerror(errno));

/**/ /* ?Connect?the?socket?with?timeout? */
#ifdef?WIN32
ioctlsocket(s,FIONBIO, & non_blocking);
#else
ioctl(s,FIONBIO, & non_blocking);
#endif
// fcntl(s,F_SETFL,?O_NONBLOCK);
if ?(connect(s,?( struct ?sockaddr? * ) & sin,? sizeof (sin))? == ? - 1 ) {
struct ?timeval?tv;?
fd_set?writefds;
// ?設(shè)置連接超時(shí)時(shí)間
tv.tv_sec? = ? 10 ;? // ?秒數(shù)
tv.tv_usec? = ? 0 ;? // ?毫秒
FD_ZERO( & writefds);?
FD_SET(s,? & writefds);?
if (select(s + 1 ,NULL, & writefds,NULL, & tv)? != ? 0 ) {?
if (FD_ISSET(s, & writefds)) {
int ?len = sizeof (error);?
// 下面的一句一定要，主要針對(duì)防火墻?
if (getsockopt(s,?SOL_SOCKET,?SO_ERROR,?( char ? * ) & error,? & len)? < ? 0 )
goto ?error_ret;?
if (error? != ? 0 )?
goto ?error_ret;?
}
else
goto ?error_ret;? // timeout?or?error?happen?
}
else ? goto ?error_ret;?;?

#ifdef?WIN32
ioctlsocket(s,FIONBIO, & blocking);
#else
ioctl(s,FIONBIO, & blocking);
#endif

}
else {
error_ret:
close(s);
err_quit( " can't?connect?to?%s:%d\n " ,?host,?port);
}
return ?s;
}

void ?err_doit( int ?errnoflag,? const ? char ? * fmt,?va_list?ap)
{
int ?errno_save;
char ?buf[MAX_STRING_LEN];

errno_save? = ?errno;?
vsprintf(buf,?fmt,?ap);
if ?(errnoflag)
sprintf(buf? + ?strlen(buf),? " :?%s " ,?strerror(errno_save));
strcat(buf,? " \n " );
fflush(stdout);
fputs(buf,?stderr);
fflush(NULL);
return ;
}

/**/ /* ?Print?a?message?and?terminate.? */
void ?err_quit( const ? char ? * fmt,?)
{
va_list?ap;
va_start(ap,?fmt);
err_doit( 0 ,?fmt,?ap);
va_end(ap);
exit( 1 );
}

#ifdef?WIN32
char ? * optarg;

char ?getopt( int ?c,? char ? * v[],? char ? * opts)
{
static ? int ?now? = ? 1 ;
char ? * p;

if ?(now? >= ?c)? return ?EOF;

if ?(v[now][ 0 ]? == ? ' - ' ? && ?(p? = ?strchr(opts,?v[now][ 1 ])))? {
optarg? = ?v[now + 1 ];
now? += 2 ;
return ? * p;
}

return ?EOF;
}

#else
extern ? char ? * optarg;
#endif

#define ?required(a)?if?(!a)?{?return?-1;?}

int ?init( int ?argc,? char ? * argv[])
{
char ?c;
// int?i,optlen;
// int?slashcnt;

i_host[ 0 ]? = ? ' \0 ' ;
i_port[ 0 ]? = ? ' \0 ' ;

while ?((c? = ?getopt(argc,?argv,? " h:? " ))? != ?EOF)? {
if ?(c? == ? ' ? ' )
return ? - 1 ;
switch ?(c)? {?
case ? ' h ' :
required(optarg);
strcpy(i_host,?optarg);
break ;
case ? ' p ' :
required(optarg);
strcpy(i_port,?optarg);
break ;
default :
return ? - 1 ;
}
}

/**/ /* ?
*?there?is?no?default?value?for?hostname,?port?number,?
*?password?or?uri
*/
if ?(i_host[ 0 ]? == ? ' \0 ' ? || ?i_port[ 0 ]? == ? ' \0 ' )
return ? - 1 ;

return ? 1 ;
}

void ?print_usage()
{
char ? * usage[]? =
{
" Usage: " ,
" ?-h?host?name " ,
" ?-p?port " ,
" example: " ,
" ?-h?127.0.0.1?-p?4001 " ,
} ;?
int ?i;

for ?(i? = ? 0 ;?i? < ? sizeof (usage)? / ? sizeof ( char * );?i ++ )
printf( " %s\n " ,?usage);

return ;
}

int ?main( int ?argc,? char ? * argv[])
{
SOCKET?fd;
int ?n;

/**/ /* ?parse?command?line?etc?? */
if ?(init(argc,?argv)? < ? 0 )? {
print_usage();
exit( 1 );
}

buf[ 0 ]? = ? ' \0 ' ;

/**/ /* ?pack?the?info?into?the?buffer? */ ?
strcpy(buf,? " HelloWorld " );

/**/ /* ?make?connection?to?the?server? */
fd? = ?tcp_connect(i_host,?(unsigned? short )atoi(i_port));

if (xnet_select(fd,? 0 ,? 500 ,?WRITE_STATUS) > 0 ) {
/**/ /* ?send?off?the?message? */
write(fd,?buf,?strlen(buf));
}
else {
err_quit( " Socket?I/O?Write?Timeout?%s:%s\n " ,?i_host,?i_port);
}

if (xnet_select(fd,? 3 ,? 0 ,?READ_STATUS) > 0 ) {
/**/ /* ?display?the?server?response? */
printf( " Server?response:\n " );
n? = ?read(fd,?buf,?BUFSIZE);
buf[n]? = ? ' \0 ' ;
printf( " %s\n " ,?buf);
}
else {
err_quit( " Socket?I/O?Read?Timeout?%s:%s\n " ,?i_host,?i_port);
}
close(fd);

#ifdef?WIN32
WSACleanup();
#endif

return ? 0 ;
}