《UNIX環境高級編程》中開發的三個函數
#include "apue.h"
#include <sys/socket.h>
#include <sys/un.h>
#include <time.h>
#include <errno.h>
#define STALE 30 /* client's name can't be older than this (sec) */
#define QLEN 10
#define CLI_PATH "./"
#define CLI_PERM S_IRWXU /* rwx for user only */
/*
* Wait for a client connection to arrive, and accept it.
* We also obtain the client's user ID from the pathname
* that it must bind before calling us.
* Returns new fd if all OK, <0 on error
*/
int
serv_accept(int listenfd, uid_t *uidptr)
{
int clifd, err, rval;
socklen_t len;
time_t staletime;
struct sockaddr_un un;
struct stat statbuf;
char *name;
/* allocate enough space for longest name plus terminating null */
if ((name = malloc(sizeof(un.sun_path + 1))) == NULL)
return(-1);
len = sizeof(un);
if ((clifd = accept(listenfd, (struct sockaddr *)&un, &len)) < 0) {
free(name);
return(-2); /* often errno=EINTR, if signal caught */
}
/* obtain the client's uid from its calling address */
len -= offsetof(struct sockaddr_un, sun_path); /* len of pathname */
memcpy(name, un.sun_path, len);
name[len] = 0; /* null terminate */
if (stat(name, &statbuf) < 0) {
rval = -3;
goto errout;
}
#ifdef S_ISSOCK /* not defined for SVR4 */
if (S_ISSOCK(statbuf.st_mode) == 0) {
rval = -4; /* not a socket */
goto errout;
}
#endif
if ((statbuf.st_mode & (S_IRWXG | S_IRWXO)) ||
(statbuf.st_mode & S_IRWXU) != S_IRWXU) {
rval = -5; /* is not rwx------ */
goto errout;
}
staletime = time(NULL) - STALE;
if (statbuf.st_atime < staletime ||
statbuf.st_ctime < staletime ||
statbuf.st_mtime < staletime) {
rval = -6; /* i-node is too old */
goto errout;
}
if (uidptr != NULL)
*uidptr = statbuf.st_uid; /* return uid of caller */
unlink(name); /* we're done with pathname now */
free(name);
return(clifd);
errout:
err = errno;
close(clifd);
free(name);
errno = err;
return(rval);
}
/*
* Create a server endpoint of a connection.
* Returns fd if all OK, <0 on error.
*/
int
serv_listen(const char *name)
{
int fd, len, err, rval;
struct sockaddr_un un;
if (strlen(name) >= sizeof(un.sun_path)) {
errno = ENAMETOOLONG;
return(-1);
}
/* create a UNIX domain stream socket */
if ((fd = socket(AF_UNIX, SOCK_STREAM, 0)) < 0)
return(-2);
unlink(name); /* in case it already exists */
/* fill in socket address structure */
memset(&un, 0, sizeof(un));
un.sun_family = AF_UNIX;
strcpy(un.sun_path, name);
len = offsetof(struct sockaddr_un, sun_path) + strlen(name);
/* bind the name to the descriptor */
if (bind(fd, (struct sockaddr *)&un, len) < 0) {
rval = -3;
goto errout;
}
if (listen(fd, QLEN) < 0) { /* tell kernel we're a server */
rval = -4;
goto errout;
}
return(fd);
errout:
err = errno;
close(fd);
errno = err;
return(rval);
}
/*
* Create a client endpoint and connect to a server.
* Returns fd if all OK, <0 on error.
*/
int
cli_conn(const char *name)
{
int fd, len, err, rval;
struct sockaddr_un un, sun;
int do_unlink = 0;
if (strlen(name) >= sizeof(un.sun_path)) {
errno = ENAMETOOLONG;
return(-1);
}
/* create a UNIX domain stream socket */
if ((fd = socket(AF_UNIX, SOCK_STREAM, 0)) < 0)
return(-1);
/* fill socket address structure with our address */
memset(&un, 0, sizeof(un));
un.sun_family = AF_UNIX;
sprintf(un.sun_path, "%s%05ld", CLI_PATH, (long)getpid());
printf("file is %s\n", un.sun_path);
len = offsetof(struct sockaddr_un, sun_path) + strlen(un.sun_path);
unlink(un.sun_path); /* in case it already exists */
if (bind(fd, (struct sockaddr *)&un, len) < 0) {
rval = -2;
goto errout;
}
if (chmod(un.sun_path, CLI_PERM) < 0) {
rval = -3;
do_unlink = 1;
goto errout;
}
/* fill socket address structure with server's address */
memset(&sun, 0, sizeof(sun));
sun.sun_family = AF_UNIX;
strcpy(sun.sun_path, name);
len = offsetof(struct sockaddr_un, sun_path) + strlen(name);
if (connect(fd, (struct sockaddr *)&sun, len) < 0) {
rval = -4;
do_unlink = 1;
goto errout;
}
return(fd);
errout:
err = errno;
close(fd);
if (do_unlink)
unlink(un.sun_path);
errno = err;
return(rval);
}
客戶端：
#include "apue.h"
#include<stdio.h>
#include<unistd.h>
#include<string.h>
#include<stdlib.h>
#include<errno.h>
#include <sys/types.h> /* See NOTES */
#include <sys/socket.h>
#include <sys/un.h>
//#include<netinet/in.h>
#define UNIXSOCKETNAME "test_socket"
#define ERR_EXIT(m) \
do \
{ \
perror(m); \
exit(EXIT_FAILURE); \
} while(0)
void echo_cli(int sock)
{
char buf1[1024] = {0};
char buf2[1024] = {0};
int ret = 0;
while(fgets(buf1, sizeof(buf1), stdin) != NULL)
{
write(sock, buf1, strlen(buf1));
ret = read(sock, buf2, sizeof(buf2));
if(ret == 0)
{
printf("server %d close\n", sock);
break;
}
printf("%s", buf2);
memset(buf1, 0, sizeof(buf1));
memset(buf2, 0, sizeof(buf2));
}
close(sock);
}
int main()
{
int sock = cli_conn(UNIXSOCKETNAME);
if(sock < 0)
ERR_EXIT("socket");
echo_cli(sock);
return 0;
}
服務器端：
#include "apue.h"
#include<stdio.h>
#include<unistd.h>
#include<string.h>
#include<stdlib.h>
#include<errno.h>
#include <sys/types.h> /* See NOTES */
#include <sys/socket.h>
#include <sys/un.h>
#define ERR_EXIT(m) \
do \
{ \
perror(m); \
exit(EXIT_FAILURE); \
} while(0)
#define UNIXSOCKETNAME "./test_socket"
void echo_cli(int sock)
{
char buf[1024] = {0};
int ret = 0;
while(1)
{
ret = read(sock, buf, sizeof(buf));
if(ret == 0)
{
printf("client %d close\n", sock);
break;
}
printf("server receive %s \n", buf);
write(sock, buf, strlen(buf));
memset(buf, 0, sizeof(buf));
}
close(sock);
}
int main()
{
int listenfd = serv_listen(UNIXSOCKETNAME);
if(listenfd < 0)
ERR_EXIT("socket");
//unlink(UNIXSOCKETNAME);
uid_t uidclient;
int conn;
pid_t pid;
while(1)
{
printf("server waiting ...\n");
conn = serv_accept(listenfd, &uidclient);
if(conn == -1)
{
if(errno == EINTR)
continue;
ERR_EXIT("accept");
}
printf("Has new client connected, conn = %d\n", conn);
pid = fork();
if(pid < 0)
ERR_EXIT("fork");
else if(pid == 0)
{
echo_cli(conn);
exit(1);
}
else
close(conn);
}
return 0;
}