Linux socket联接句柄进程间传送示例代码
Linux socket连接句柄进程间传送示例代码
准备做一个网络侦听进程和数据处理进程分离的模块，侦听进程和数据处理进程一对多关系，希望侦听进程在收到连接后，把socket句柄传送给空闲的数据处理进程。对于进程间文件描述符传送，先做了如下的示例程序。
#include <stdio.h>
#include <stdlib.h>
#include <stdint.h>
#include <errno.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <sys/select.h>
#include <sys/un.h>
#include <netinet/in.h>
#include <sys/wait.h>
#include <sys/uio.h>
/**
* Author: luckysym
* Date: 3/22/2013
*
* Global Variables:
* int client_pipe_fd 与子进程通讯的fd，用于向子进程发送远程socket句柄
*
* Functions:
* create_inet_server() 创建tcp侦听服务，父进程调用
* create_pipe_server() 创建本地管道侦听服务，父进程调用
* pipe_connect() 子进程连接父进程的管道
* inet_client_connected() 父进程收到远程tcp连接的处理函数，收到连接后将句柄发送到子进程
* pipe_client_connected() 父进程收到子进程的管道连接处理函数，函数中将管道句柄保存为全局变量
* wait_for_connect() 父进程等待socket连接，包括等待子进程管道连接，或者远程tcp连接，
* 收到连接后根据socket类型分别调用inet_client_connected()
* 或pipe_client_connected()
* recv_fd() 子进程用于接收父进程发来的远程socket句柄
*
* child_main() 子进程主函数
*
* 程序测试执行过程：
* 1. 父进程main函数启动后立即fork一个子进程，然后创建管道监听
* 2. 子进程启动后，等待5秒钟后（保证父进程管道创建完毕），连接父进程管道
* 3. 父进程收到子进程的管道连接后，保存管道通讯句柄，然后创建tcp侦听（端口30098）
* 4. 子进程连接父进程完毕后，等待接收父进程的管道消息
*
* 4. 远程启动一个telnet连接到30098端口。
* 5. 父进程收到连接后，首先向远程发送"Hello Client"消息
* 6. 然后父进程将tcp连接句柄通过管道发送给子进程（发送过程中句柄被复制）
* 7. 发送完毕后，父进程关闭tcp连接句柄
* 8. 子进程收到tcp连接句柄后，向远程telnet发送"This is child process speaking"消息
* 然后准备读取该tcp连接句柄。
* 9. 远程telnet端输入并发送一条文本消息，子进程在收到消息后会将其打印出（以[child]为前缀）
* 10. 子进程打印出消息后，关闭tcp连接句柄，telnet端连接同时关闭。
*/
int client_pipe_fd = 0;
int create_inet_server(uint16_t port)
{
int fd = socket(PF_INET, SOCK_STREAM | SOCK_NONBLOCK, 0);
if ( fd < 0 ) {
printf("failed to create socket, err=%d\n", errno);
return fd;
}
struct sockaddr_in laddr;
laddr.sin_family = AF_INET;
laddr.sin_port = htons(port);
laddr.sin_addr.s_addr = htonl(INADDR_ANY);
int ret = bind(fd, (struct sockaddr*)&laddr, sizeof(laddr));
if ( ret < 0 ) {
printf("failed to bind local port %d, err=%d\n", port, errno);
return ret;
}
ret = listen(fd, 10);
if ( ret < 0 ) {
printf("failed to listen, err=%d", errno);
return ret;
}
return fd;
}
int create_pipe_server(const char * path)
{
int fd = socket(PF_UNIX, SOCK_STREAM , 0);
if ( fd < 0 ) {
printf("failed to create pipe, err=%d\n", errno);
return fd;
}
struct sockaddr_un laddr;
memset(&laddr, 0, sizeof(laddr));
laddr.sun_family = AF_LOCAL;
strcpy(laddr.sun_path, path);
//laddr.sun_len = sizeof(laddr.sun_length) + sizeof(laddr.sun_family) + strlen(laddr.sun_path) + 1;
int ret = bind(fd, (struct sockaddr*)&laddr, sizeof(laddr));
if ( ret < 0 ) {
printf("failed to bind local path %s, err=%d\n", path, errno);
return ret;
}
ret = listen(fd, 10);
if ( ret < 0 ) {
printf("failed to listen pipe, err=%d", errno);
return ret;
}
return fd;
}
int pipe_connect(const char * local, const char * remote)
{
struct sockaddr_un laddr;
struct sockaddr_un raddr;
laddr.sun_family = AF_LOCAL;
raddr.sun_family = AF_LOCAL;
strcpy(laddr.sun_path, local);
strcpy(raddr.sun_path, remote);
int llen = strlen(laddr.sun_path) + sizeof(laddr.sun_family) + 1;
int rlen = strlen(raddr.sun_path) + sizeof(raddr.sun_family) + 1;
unlink(local);
int fd = socket(PF_UNIX, SOCK_STREAM, 0);
if (fd < 0) {
printf("create client pipe socket fail, err=%d\n", errno);
return fd;
}
int ret = bind(fd, (struct sockaddr *)&laddr, llen);
if ( ret < 0) {
printf("bind local pipe path fail - %s, %d\n", local, errno);
return ret;
}
ret = connect(fd, (struct sockaddr *)&raddr, rlen );
if (ret < 0 ) {
printf("connect to remote pipe fail, errno=%d\n", errno);
return ret;
}
return fd;
}
int inet_client_connected(int sock, const struct sockaddr * raddr, socklen_t size)
{
printf("Connection comming\n");
int ret = write(sock, "Hello Client!\n", 15);
struct cmsghdr * cmptr = 0;
struct msghdr msg;
struct iovec iov[1];
char buf[2];
iov[0].iov_base = buf;
iov[0].iov_len = 2;
msg.msg_iov = iov;
msg.msg_iovlen = 1;
msg.msg_name = NULL;
msg.msg_namelen = 0;
cmptr = (struct cmsghdr *)malloc(sizeof(struct cmsghdr) + sizeof(int));
cmptr->cmsg_level = SOL_SOCKET;
cmptr->cmsg_type = SCM_RIGHTS;
cmptr->cmsg_len = sizeof(struct cmsghdr) + sizeof(int);
*(int *)CMSG_DATA(cmptr) = sock;
msg.msg_control = cmptr;
msg.msg_controllen = sizeof(struct cmsghdr) + sizeof(int);
buf[1] = 0; buf[0] = 1;
ret = sendmsg(client_pipe_fd, &msg, 0);
if ( ret != 2) {
printf("send socket fd failed, ret=%d, err=%d\n", ret, errno);
}
free(cmptr);
close(sock);
return 0;
}
int pipe_client_connected(int sock, const struct sockaddr * addr, socklen_t size)
{
const struct sockaddr_un * paddr = (const struct sockaddr_un *)addr;
printf("client pipe connected fd=%d\n", sock);
client_pipe_fd = sock;
return -1;
}
#define INET_SOCK 0
#define PIPE_SOCK 1
int wait_for_connect(int sock, int type)
{
fd_set rds;
int ret = 0;
struct timeval times;
struct sockaddr_in riaddr;
struct sockaddr_un ruaddr;
socklen_t rsize[] = { sizeof(riaddr), sizeof(ruaddr) };
struct sockaddr * paddrs[] = { (struct sockaddr*)&riaddr, (struct sockaddr*)&ruaddr};
while ( !ret ) {
times.tv_sec = 1;
times.tv_usec = 0;
FD_ZERO(&rds);
FD_SET(sock, &rds);
ret = select(sock + 1, &rds, 0, 0, ×);
if ( ret < 0 ) {
printf("select fail. err=%d\n", errno);
break;
} else if ( ret == 0) {
continue;
} else {
ret = accept(sock, paddrs[type], &rsize[type]);
if ( ret < 0 ) {
break;
} else {
if ( type == INET_SOCK) {
ret = inet_client_connected(ret, paddrs[INET_SOCK], rsize[INET_SOCK]);
} else if ( type == PIPE_SOCK ) {
ret = pipe_client_connected(ret, paddrs[PIPE_SOCK], rsize[PIPE_SOCK]);
}
if ( ret < 0 ) break;
}
}
ret = 0;
} // while
return 0;
}
int recv_fd(int pipefd)
{
char buf[2];
int newfd = -1;
struct iovec iov[1];
struct msghdr msg;
struct cmsghdr * cmptr = (struct cmsghdr *)malloc(sizeof(struct cmsghdr) + sizeof(int));
iov[0].iov_base = buf;
iov[0].iov_len = sizeof(buf);
msg.msg_iov = iov;
msg.msg_iovlen = 1;
msg.msg_name = NULL;
msg.msg_namelen = 0;
msg.msg_control = cmptr;
msg.msg_controllen = sizeof(struct cmsghdr) + sizeof(int);
int ret = recvmsg(pipefd, &msg, 0);
printf("[child] recvmsg returned, ret=%d\n", ret);
if ( ret < 0 ) {
printf("recvmsg failed, err=%d\n", errno);
} else {
newfd = *(int*)CMSG_DATA(cmptr);
printf("[child] recv the socket fd: %d\n", newfd);
}
free(cmptr);
return newfd;
}
int child_main()
{
printf("[child] child process running, wait 5 secs for pipe server creation\n");
sleep(5);
int fd = pipe_connect("/tmp/pipe_local", "/tmp/fd_trans");
printf("[child] connect to remote pipe fd = %d\n", fd);
int newfd = recv_fd(fd);
int ret = write(newfd, "[child] This is child process speaking!\n", 41);
if ( ret < 0 ) {
printf("[child] write message to remote fail: ret=%d, err=%d\n", ret, errno);
}
char buf[256];
memset(buf, 0, sizeof(buf));
ret = read(newfd, buf, 256);
if ( ret < 0) {
printf("[child] failed to recv remote message: \n");
} else {
buf[ret] = 0;
printf("[child] remote message arrived: %s\n", buf);
}
printf("[child] child exiting\n");
close(fd);
close(newfd);
return 0;
}
int main(int argc, char *argv)
{
if ( fork() == 0 ) {
exit(child_main());
}
unlink("/tmp/fd_trans");
int pipesock = create_pipe_server("/tmp/fd_trans");
if (pipesock >= 0) {
printf("pipe server created, now wait for child connecting\n");
wait_for_connect(pipesock, PIPE_SOCK);
}
int inetsock = create_inet_server(30098);
if ( inetsock >= 0 ) wait_for_connect(inetsock, INET_SOCK);
close(client_pipe_fd);
close(pipesock);
close(inetsock);
return 0;
}