客戶端的工作流程：首先調(diào)用socket函數(shù)創(chuàng)建一個Socket，然后調(diào)用bind函數(shù)將其與本機地址以及一個本地端口號綁定，請求連接服務(wù)器，通過新的socket向客戶端發(fā)送字符串” hi,I am client!”。最后關(guān)閉該socket。

main()

{

int cli_sockfd; /*客戶端SOCKET */

int addrlen;

char seraddr[14];

struct sockaddr_in ser_addr, /* 服務(wù)器的地址*/

cli_addr; /* 客戶端的地址*/

char msg[MAX_MSG_SIZE]; /* 緩沖區(qū)*/

GetServerAddr( seraddr );

cli_sockfd = socket( AF_INET, SOCK_STREAM, 0 ); /*創(chuàng)建連接的SOCKET */

if ( ser_sockfd < 0 )

{ /*創(chuàng)建失敗 */

fprintf( stderr, "socker Error:%sn", strerror( errno ) );

exit( 1 );

}

/* 初始化客戶端地址*/

addrlen = sizeof(struct sockaddr_in);

bzero( &ser_addr, addrlen );

cli_addr.sin_family = AF_INET;

cli_addr.sin_addr.s_addr = htonl( INADDR_ANY );

cli_addr.sin_port = 0;

if ( bind( cli_sockfd, (struct sockaddr *) &cli_addr, addrlen ) < 0 )

{

/*棒定失敗 */

fprintf( stderr, "Bind Error:%sn", strerror( errno ) );

exit( 1 );

}

/* 初始化服務(wù)器地址*/

addrlen = sizeof(struct sockaddr_in);

bzero( &ser_addr, addrlen );

ser_addr.sin_family = AF_INET;

ser_addr.sin_addr.s_addr = inet_addr( seraddr );

ser_addr.sin_port = htons( SERVER_PORT );

if ( connect( cli_sockfd, (struct sockaddr *) &ser_addr, &addrlen ) != 0 ) / 請求連接 /

{

/*連接失敗 */

fprintf( stderr, "Connect Error:%sn", strerror( errno ) );

close( cli_sockfd );

exit( 1 );

}

strcpy( msg, "hi,I am client!" );

send( sockfd, msg, sizeof(msg), 0 ); / 發(fā)送數(shù)據(jù) /

recv( sockfd, msg, MAX_MSG_SIZE, 0 ); /* 接受數(shù)據(jù)*/

printf( "%sn", msg ); /*在屏幕上打印出來 */

close( cli_sockfd );

}

服務(wù)器的工作流程：首先調(diào)用socket函數(shù)創(chuàng)建一個Socket，然后調(diào)用bind函數(shù)將其與本機地址以及一個本地端口號綁定，接收到一個客戶端時，服務(wù)器顯示該客戶端的IP地址，并將字串返回給客戶端。

3、UDP/IP應(yīng)用編程接口（API）

int main( int argc, char **argv )

{

int ser_sockfd;

int len;

/* int addrlen; */

socklen_t addrlen;

char seraddr[100];

struct sockaddr_in ser_addr;

/ 建立socket /

ser_sockfd = socket( AF_INET, SOCK_DGRAM, 0 );

if ( ser_sockfd < 0 )

{

printf( "I cannot socket successn" );

return(1);

}

/ 填寫sockaddr_in 結(jié)構(gòu) /

addrlen = sizeof(struct sockaddr_in);

bzero( &ser_addr, addrlen );

ser_addr.sin_family = AF_INET;

ser_addr.sin_addr.s_addr = htonl( INADDR_ANY );

ser_addr.sin_port = htons( SERVER_PORT );

/*綁定客戶端

• if(bind(ser_sockfd,(struct sockaddr *)&ser_addr,addrlen)<0)
• {
• printf("connect");
• return 1;
• }
• while(1)
• {
• bzero(seraddr,sizeof(seraddr));
• len=recvfrom(ser_sockfd,seraddr,sizeof(seraddr),0,(struct sockaddr*)&ser_addr,&addrlen);
• / 顯示client端的網(wǎng)絡(luò)地址 /

printf( "receive from %sn", inet_ntoa( ser_addr.sin_addr ) );

/ 顯示客戶端發(fā)來的字串 /

printf( "recevce:%s", seraddr );

/ 將字串返回給client端 /

sendto( ser_sockfd, seraddr, len, 0, (struct sockaddr *) &ser_addr, addrlen );

}

客戶端的工作流程：首先調(diào)用socket函數(shù)創(chuàng)建一個Socket，填寫服務(wù)器地址及端口號，從標(biāo)準(zhǔn)輸入設(shè)備中取得字符串，將字符串傳送給服務(wù)器端，并接收服務(wù)器端返回的字符串。最后關(guān)閉該socket。

int GetServerAddr( char * addrname )

{

printf( "please input server addr:" );

scanf( "%s", addrname );

return(1);

}

int main( int argc, char **argv )

{

int cli_sockfd;

int len;

socklen_t addrlen;

char seraddr[14];

struct sockaddr_in cli_addr;

char buffer[256];

GetServerAddr( seraddr );

/* 建立socket*/

cli_sockfd = socket( AF_INET, SOCK_DGRAM, 0 );

if ( cli_sockfd < 0 )

{

printf( "I cannot socket successn" );

return(1);

}

/* 填寫sockaddr_in*/

addrlen = sizeof(struct sockaddr_in);

bzero( &cli_addr, addrlen );

cli_addr.sin_family = AF_INET;

cli_addr.sin_addr.s_addr = inet_addr( seraddr );

/* cli_addr.sin_addr.s_addr=htonl(INADDR_ANY); */

cli_addr.sin_port = htons( SERVER_PORT );

bzero( buffer, sizeof(buffer) );

/* 從標(biāo)準(zhǔn)輸入設(shè)備取得字符串*/

len = read( STDIN_FILENO, buffer, sizeof(buffer) );

/* 將字符串傳送給server端*/

sendto( cli_sockfd, buffer, len, 0, (struct sockaddr *) &cli_addr, addrlen );

/* 接收server端返回的字符串*/

len = recvfrom( cli_sockfd, buffer, sizeof(buffer), 0, (struct sockaddr *) &cli_addr, &addrlen );

/* printf("receive from %sn",inet_ntoa(cli_addr.sin_addr)); */

printf( "receive: %s", buffer );

close( cli_sockfd );

}

四、調(diào)試

Makefile文件為：

CC=gcc

all:server client

CFLAGS=-o

server: server.c

**(CC) **(CFLAGS) $@ server.c

client: client.c

**(CC) **(CFLAGS) $@ client.c

clean:

rm -f server client

運行結(jié)果如下圖：在shell中執(zhí)行make進(jìn)行編譯，make clean刪除生成文件。