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? ? ?socket進(jìn)程通信與網(wǎng)絡(luò)通信使用的是統(tǒng)一套接口，只是地址結(jié)構(gòu)與某些參數(shù)不同。
一。創(chuàng)建socket服務(wù)端的流程如下：
（1）創(chuàng)建socket，類(lèi)型為AF_LOCAL或AF_UNIX，表示用于進(jìn)程通信：
[cpp]?view plain?copy
int?server_fd;??
int?client_fd;//client?file?descriptor??
struct?sockaddr_un?server_addr;???
struct?sockaddr_un?client_addr;??
size_t?server_len,client_len;??
//cteate?server?socket??
//delete?old?socket?file??
unlink(SERVER_NAME);??
if?((server_fd?=?socket(AF_UNIX,??SOCK_STREAM,??0))?==?-1)?{??
perror("socket");??
exit(1);??
}??
(2)命名socket。這里面有一個(gè)很關(guān)鍵的東西，socket進(jìn)程通信命名方式有兩種。一是普通的命名，socket會(huì)根據(jù)此命名創(chuàng)建一個(gè)同名的socket文件，客戶(hù)端連接的時(shí)候通過(guò)讀取該socket文件連接到socket服務(wù)端。這種方式的弊端是服務(wù)端必須對(duì)socket文件的路徑具備寫(xiě)權(quán)限，客戶(hù)端必須知道socket文件路徑，且必須對(duì)該路徑有讀權(quán)限。另外一種命名方式是抽象命名空間，這種方式不需要?jiǎng)?chuàng)建socket文件，只需要命名一個(gè)全局名字，即可讓客戶(hù)端根據(jù)此名字進(jìn)行連接。后者的實(shí)現(xiàn)過(guò)程與前者的差別是，后者在對(duì)地址結(jié)構(gòu)成員sun_path數(shù)組賦值的時(shí)候，必須把第一個(gè)字節(jié)置0，即sun_path[0] = 0，下面用代碼說(shuō)明：
第一種方式：
[cpp]?view plain?copy
//name?the?server?socket???
server_addr.sun_family?=?AF_UNIX;??
strcpy(server_addr.sun_path,SERVER_NAME);??
server_len?=?sizeof(struct?sockaddr_un);??
client_len?=?server_len;??
第二種方式：
[cpp]?view plain?copy
//name?the?socket??
server_addr.sun_family?=?AF_UNIX;??
strcpy(server_addr.sun_path,?SERVER_NAME);??
server_addr.sun_path[0]=0;??
//server_len?=?sizeof(server_addr);??
server_len?=?strlen(SERVER_NAME)??+?offsetof(struct?sockaddr_un,?sun_path);??
其中，offsetof函數(shù)在#include 頭文件中定義。因第二種方式的首字節(jié)置0，我們可以在命名字符串SERVER_NAME前添加一個(gè)占位字符串，例如:
[cpp]?view plain?copy
#define?SERVER_NAME?@socket_server??
前面的@符號(hào)就表示占位符，不算為實(shí)際名稱(chēng)。
或者可以把第二種方式的實(shí)現(xiàn)封裝成一個(gè)函數(shù)：
[cpp]?view plain?copy
int?makeAddr(const?char*?name,?struct?sockaddr_un*?pAddr,?socklen_t*?pSockLen)??
{??
int?nameLen?=?strlen(name);??
if?(nameLen?>=?(int)?sizeof(pAddr->sun_path)?-1)??/*?too?long??*/??
return?-1;??
pAddr->sun_path[0]?=?'\0';??/*?abstract?namespace?*/??
strcpy(pAddr->sun_path+1,?name);??
pAddr->sun_family?=?AF_UNIX;??
*pSockLen?=?1?+?nameLen?+?offsetof(struct?sockaddr_un,?sun_path);??
return?0;??
}??
像下面這樣使用這個(gè)函數(shù)：
[cpp]?view plain?copy
makeAddr("server_socket",?&server_addr,?&server_len);??
提示：客戶(hù)端連接服務(wù)器的時(shí)候，必須與服務(wù)端的命名方式相同，即如果服務(wù)端是普通命名方式，客戶(hù)端的地址也必須是普通命名方式；如果服務(wù)端是抽象命名方式，客戶(hù)端的地址也必須是抽象命名方式。
（3）綁定并偵聽(tīng)
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bind(server_sockfd,?(struct?sockaddr?*)&server_addr,?server_len);??
//listen?the?server??
listen(server_sockfd,?5);??
（4）等待客戶(hù)端連接，并讀寫(xiě)數(shù)據(jù)。
[cpp]?view plain?copy
while(1){??
printf("server?waiting...\n");??
//accept?client?connect??
client_len?=?sizeof(client_addr);??
client_sockfd?=?accept(server_sockfd,(struct?sockaddr*)&client_addr,?&client_len);??
//read??data?from?client?socket??
read(client_sockfd,?&ch,?1);??
printf("read?from?client?%d:?%c",client_sockfd,ch);??
ch?++;??
write(client_sockfd,?&ch,?1);??
close(client_sockfd);??
usleep(100);//1000?miliseconds?=?1?second??
}??
二 socket客戶(hù)端創(chuàng)建流程
（1）創(chuàng)建socket
（2）命名socket
（3）連接到服務(wù)端：
[cpp]?view plain?copy
//connect?to?server??
result?=?connect(sockfd,?(struct?sockaddr*)&address,?len);??
（4）與服務(wù)端進(jìn)行通信
[cpp]?view plain?copy
//communicate?with?server?socket??
while(1)??
{??
printf("set?send?content:");??
scanf("%c",&ch);??
write(sockfd,?&ch,?1);??
printf("send?to?server:%c?\n",ch);??
read(sockfd,?&ch,?1);??
printf("read?from?server:?%c\n",?ch);??
}??
完整代碼如下：
（1）服務(wù)端server.c：
[cpp]?view plain?copy
#include??
#include??
#include??
#include??
#include??
#include??
#include???
#define?SERVER_NAME?"@server_socket"??
/*?
*?Create?a?UNIX-domain?socket?address?in?the?Linux?"abstract?namespace".?
*?
*?The?socket?code?doesn't?require?null?termination?on?the?filename,?but?
*?we?do?it?anyway?so?string?functions?work.?
*/??
int?makeAddr(const?char*?name,?struct?sockaddr_un*?pAddr,?socklen_t*?pSockLen)??
{??
int?nameLen?=?strlen(name);??
if?(nameLen?>=?(int)?sizeof(pAddr->sun_path)?-1)??/*?too?long??*/??
return?-1;??
pAddr->sun_path[0]?=?'\0';??/*?abstract?namespace?*/??
strcpy(pAddr->sun_path+1,?name);??
pAddr->sun_family?=?AF_UNIX;??
*pSockLen?=?1?+?nameLen?+?offsetof(struct?sockaddr_un,?sun_path);??
return?0;??
}??
int?main()??
{??
int?server_sockfd,?client_sockfd;??
socklen_t?server_len,?client_len;??
struct?sockaddr_un?server_addr;??
struct?sockaddr_un?client_addr;??
char?ch;??
int?nread;??
//delete?the?old?server?socket??
//unlink("server_socket");??
//create?socket??
server_sockfd?=?socket(AF_UNIX,?SOCK_STREAM,?0);??
//name?the?socket??
server_addr.sun_family?=?AF_UNIX;??
strcpy(server_addr.sun_path,?SERVER_NAME);??
server_addr.sun_path[0]=0;??
//server_len?=?sizeof(server_addr);??
server_len?=?strlen(SERVER_NAME)??+?offsetof(struct?sockaddr_un,?sun_path);??
//makeAddr("server_socket",?&server_addr,?&server_len);??
bind(server_sockfd,?(struct?sockaddr?*)&server_addr,?server_len);??
//listen?the?server??
listen(server_sockfd,?5);??
client_sockfd?=?-1;??
client_len?=?sizeof(client_addr);??
while(1){??
printf("server?waiting...\n");??
//accept?client?connect??
if(client_sockfd?==?-1){??
client_sockfd?=?accept(server_sockfd,(struct?sockaddr*)&client_addr,?&client_len);??
}??
//read??data?from?client?socket??
nread?=?read(client_sockfd,?&ch,?1);??
if(nread?==?0){//client?disconnected??
printf("client?%d?disconnected\n",client_sockfd);??
client_sockfd?=?-1;??
}??
else{??
printf("read?from?client?%d:?%c\n",client_sockfd,ch);??
ch?++;??
write(client_sockfd,?&ch,?1);??
}??
usleep(100);//1000?miliseconds?=?1?second??
}??
return?0;??
}??
（2）客戶(hù)端client.c
[cpp]?view plain?copy
#include??
#include??
#include??
#include??
#include??
#include??
#include???
#define?SERVER_NAME?"@server_socket"??
/*?
*?Create?a?UNIX-domain?socket?address?in?the?Linux?"abstract?namespace".?
*?
*?The?socket?code?doesn't?require?null?termination?on?the?filename,?but?
*?we?do?it?anyway?so?string?functions?work.?
*/??
int?makeAddr(const?char*?name,?struct?sockaddr_un*?pAddr,?socklen_t*?pSockLen)??
{??
int?nameLen?=?strlen(name);??
if?(nameLen?>=?(int)?sizeof(pAddr->sun_path)?-1)??/*?too?long??*/??
return?-1;??
pAddr->sun_path[0]?=?'\0';??/*?abstract?namespace?*/??
strcpy(pAddr->sun_path+1,?name);??
pAddr->sun_family?=?AF_UNIX;??
*pSockLen?=?1?+?nameLen?+?offsetof(struct?sockaddr_un,?sun_path);??
return?0;??
}??
int?main()??
{??
int?sockfd;??
socklen_t?len;??
struct?sockaddr_un?address;??
int?result;??
char?ch?=?'A';??
//create?socket???
sockfd?=?socket(AF_UNIX,?SOCK_STREAM,?0);??
//name?the?server?socket??
//makeAddr("server_socket",?&address,?&len);??
address.sun_family?=?AF_UNIX;??
strcpy(address.sun_path,?SERVER_NAME);??
address.sun_path[0]=0;??
//len?=?sizeof(address);??
len?=??strlen(SERVER_NAME)??+?offsetof(struct?sockaddr_un,?sun_path);??
//connect?to?server??
result?=?connect(sockfd,?(struct?sockaddr*)&address,?len);??
if(result?==?-1)??
{??
perror("opps:client1");??
exit(1);??
}??
//communicate?with?server?socket??
while(1)??
{??
printf("set?send?content:");??
scanf("%c",&ch);??
write(sockfd,?&ch,?1);??
printf("send?to?server:%c?\n",ch);??
read(sockfd,?&ch,?1);??
printf("read?from?server:?%c\n",?ch);??
}??
exit(0);??
} ?
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