使用套接字实现本机进程间通信
为本机进程间通信而生——域套接字
实现方法
- 第一种：使用网络套接字
- 比如使用TCP/IP协议族来实现，不管是使用TCP还是使用UDP都可以，只要目标ip指定为本机IP或者127.0.0.1网环地址，即可实现本机进程间通信。
- 事实上使用实现网络通信的“网络套接字”来实现本机进程间通信，有点大才小用，如果想要使用套接字来实现本机进程间通信的话，我们应该是使用“域套接字”，而不是“网络套接字”。
- 实现本机进程间通信，“域套接字”的效率高于“网络套接字”。
- 第二种：使用“域套接字”
- 创建“域套接字文件时”，如果指定的是“域套通信协议族”的话，这个套接字文件就被称为“域套接字文件”简称域套接字。
- 域套接字不能实现跨进程间通信，只能用来实现“本机进程间通信”，而且还是专业的“本机间通信”。
- 总结以下，到目前为止，进程间通信的方式有那些?
- 信号
- 管道(无名、有名)
- system V IPC(消息队列、共享内存、无名信号量)
- 域套接字
域套接字的实现
有两种，分别是
- 字节流的“域套接字”
- 数据报的“域套接字”
字节流“域套接字”
- 编程模型
- 编程模型与TCP的编程模型完全一样。
- 虽然编程模型与TCP一样，但是还是有所不同的，其中最大的不同就是，绑定时设置的结构体是struct sockaddr_un，而不是struct sockaddr_in
- struct sockaddr_un是域套接字使用的，struct sockaddr_in是TCP套接字使用的
-
#define UNIX_PATH_MAX 108 struct sockaddr_un { sa_family_t sun_family; /*PF_UNIX或AF_UNIX */ char sun_path[UNIX_PATH_MAX]; /* 路径名 */ };
设置这个结构体时，
sun_family = AF_UNIX或者AF_LOCAL
sun_path = 一个文件路径名//注意不是IP和端口，域套接字实现本机进程间通信时，用不到ip和端口。
bind绑定结构体的内容时，会创建“所设置路径名的”文件。
疑问：这个文件起什么作用?
简单理解就是，起到与ip和端口类似的作用
TCP代码
程序演示：
server.c
int cfd;
void signal_fun(int signo)
{
if (SIGINT == signo)
{
/* Delete file! */
remove("./UNIX_SOCK");
exit(0);
}
}
void *pth_func(void *arg)
{
int ret = -1;
char buf[100] = {0};
while(1)
{
bzero(buf, sizeof(buf));
ret = read(cfd, buf, sizeof(buf));
if (ret == -1) print_err("read failed", __LINE__, errno);
else if (ret > 0)
{
printf("%s\n", buf);
}
}
}
int main(int argc, char *argv[])
{
int sockfd = -1;
int ret = -1;
char buf[100] = {0};
pthread_t tid;
struct sockaddr_un addr = {0};
signal(SIGINT, signal_fun);
//!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
sockfd = socket(PF_UNIX, SOCK_STREAM, 0);
if (sockfd == -1) print_err("socket failed", __LINE__, errno);
addr.sun_family = AF_UNIX;
strcpy(addr.sun_path, "UNIX_SOCK");
ret = bind(sockfd, (struct sockaddr *)&addr, sizeof(addr));
if (ret == -1) print_err("bind failed", __LINE__, errno);
ret = listen(sockfd, 3);
if (ret == -1) print_err("listen failed", __LINE__, errno);
cfd = accept(sockfd, NULL, 0);
if (cfd == -1) print_err("accept failed", __LINE__, errno);
ret = pthread_create(&tid, NULL, pth_func, NULL);
if (ret != 0) print_err("pthread_create failed", __LINE__, ret);
while(1)
{
bzero(buf, sizeof(buf));
scanf("%s", buf);
ret = write(cfd, buf, sizeof(buf));
if (ret == -1) print_err("write failed", __LINE__, errno);
}
return 0;
}
client.c
int sockfd;
void *pth_func(void *arg)
{
int ret = -1;
char buf[100] = {0};
while(1)
{
bzero(buf, sizeof(buf));
ret = read(sockfd, buf, sizeof(buf));
if (ret == -1) print_err("read failed", __LINE__, errno);
else if (ret > 0)
{
printf("%s\n", buf);
}
}
}
int main(int argc, char *argv[])
{
int ret = -1;
char buf[100] = {0};
pthread_t tid;
struct sockaddr_un addr = {0};
//!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
sockfd = socket(PF_UNIX, SOCK_STREAM, 0);
if (sockfd == -1) print_err("socket failed", __LINE__, errno);
addr.sun_family = AF_UNIX;
strcpy(addr.sun_path, "./UNIX_SOCK");
ret = connect(sockfd, (struct sockaddr *)&addr, sizeof(addr));
if (ret == -1) print_err("connect failed", __LINE__, errno);
ret = pthread_create(&tid, NULL, pth_func, NULL);
if (ret != 0) print_err("pthread_create failed", __LINE__, ret);
while(1)
{
bzero(buf, sizeof(buf));
scanf("%s", buf);
ret = write(sockfd, buf, sizeof(buf));
if (ret == -1) print_err("write failed", __LINE__, errno);
}
return 0;
}
UDP
代码演示：
A
int sockfd;
struct sockaddr_un peer_addr;
void signal_fun(int signo)
{
if (SIGINT == signo)
{
/* Delete file! */
remove("./unix_sock_A");
exit(0);
}
}
void *pth_func(void *arg)
{
int ret = -1;
char buf[100] = {0};
int peer_addr_size = sizeof(peer_addr);
while(1)
{
bzero(buf, sizeof(buf));
ret = recvfrom(sockfd, buf, sizeof(buf), 0, \
(struct sockaddr *)&peer_addr, &peer_addr_size);
if (ret == -1) print_err("recvfrom failed", __LINE__, errno);
else if (ret > 0)
{
printf("%s\n", buf);
}
}
}
int main(int argc, char *argv[])
{
int ret;
char buf[100] = {0};
pthread_t tid;
if (argc != 2)
{
printf("./a.out filename\n");
}
signal(SIGINT, signal_fun);
sockfd = socket(AF_UNIX, SOCK_DGRAM, 0);
if (sockfd == -1) print_err("socket failed", __LINE__, errno);
struct sockaddr_un addr = {0};
addr.sun_family = AF_UNIX;
strcpy(addr.sun_path, "./unix_sock_A");
ret = bind(sockfd, (struct sockaddr *)&addr, sizeof(addr));
if (ret == -1) print_err("bind failed", __LINE__, errno);
ret = pthread_create(&tid, NULL, pth_func, NULL);
if (ret != 0) print_err("pthread_create failed", __LINE__, ret);
while(1)
{
peer_addr.sun_family = AF_UNIX;
strcpy(peer_addr.sun_path, argv[1]);
bzero(buf, sizeof(buf));
scanf("%s", buf);
ret = sendto(sockfd, buf, sizeof(buf), 0, \
(struct sockaddr *)&peer_addr, sizeof(peer_addr));
if (ret == -1) print_err("sendto failed", __LINE__, errno);
}
return 0;
}
B
int sockfd;
struct sockaddr_un peer_addr;
void signal_fun(int signo)
{
if (SIGINT == signo)
{
/* Delete file! */
remove("./unix_sock_B");
exit(0);
}
}
void *pth_func(void *arg)
{
int ret = -1;
char buf[100] = {0};
int peer_addr_size = sizeof(peer_addr);
while(1)
{
bzero(buf, sizeof(buf));
ret = recvfrom(sockfd, buf, sizeof(buf), 0, \
(struct sockaddr *)&peer_addr, &peer_addr_size);
if (ret == -1) print_err("recvfrom failed", __LINE__, errno);
else if (ret > 0)
{
printf("%s\n", buf);
}
}
}
int main(int argc, char *argv[])
{
int ret;
char buf[100] = {0};
pthread_t tid;
if (argc != 2)
{
printf("./a.out filename\n");
}
signal(SIGINT, signal_fun);
sockfd = socket(AF_UNIX, SOCK_DGRAM, 0);
if (sockfd == -1) print_err("socket failed", __LINE__, errno);
struct sockaddr_un addr = {0};
addr.sun_family = AF_UNIX;
strcpy(addr.sun_path, "./unix_sock_B");
ret = bind(sockfd, (struct sockaddr *)&addr, sizeof(addr));
if (ret == -1) print_err("bind failed", __LINE__, errno);
ret = pthread_create(&tid, NULL, pth_func, NULL);
if (ret != 0) print_err("pthread_create failed", __LINE__, ret);
while(1)
{
peer_addr.sun_family = AF_UNIX;
strcpy(peer_addr.sun_path, argv[1]);
bzero(buf, sizeof(buf));
scanf("%s", buf);
ret = sendto(sockfd, buf, sizeof(buf), 0, \
(struct sockaddr *)&peer_addr, sizeof(peer_addr));
if (ret == -1) print_err("sendto failed", __LINE__, errno);
}
return 0;
}
