linux动态连接

总结:至少2个文件和共2条指令

我使用的文件是sock.h 和 wrapper.c 

使用的指令是

$ gcc wrapper.c -o wrapper.o -c

$ gcc -shared -fPIC -o libnetlib.so wrapper.o

这样就生成了libnetlib.so文件了,将libnetlib.so复制到/lib中.

并将sock.h复制到/usr/include.即可使用

以后需要用到这个库函数的时候,添加这个库函数即可:

例如:

$gcc srv.c -o srv -lnetlib

$gcc cli.c -o cli -lnetlib

下面贴出sock.h 和wrapper.c 的代码:

sock.h:

#ifndef _SOCK_H__
#define _SOCK_H__

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <poll.h>

#include <string.h>
#include <strings.h>

#include <sys/socket.h>
#include <sys/types.h>
#include <arpa/inet.h>
#include <netinet/in.h>

int Socket(int, int, int);
int Inet_pton(int, const char *, void *);
int Bind(int, const struct sockaddr *, socklen_t);
int Listen(int, int);
int Accept(int, struct sockaddr *, socklen_t *);
int Connect(int, const struct sockaddr *, socklen_t);
int Setsockopt(int, int, int, const void *, socklen_t);

int TCP_listen(const char *, unsigned short, int, int *,
		struct sockaddr *, socklen_t *);
int TCP_connect(const char *, const unsigned short);

pid_t Fork(void);
ssize_t Write(int, const void*, size_t);
ssize_t Read(int, void*, size_t);

#endif

wrapper.c:

#include "sock.h"
#include <stdlib.h>
#include <errno.h>

int Socket(int domain, int type, int protocol)
{
	int sockfd;
	sockfd = socket(domain, type, protocol);

	if(sockfd == -1){
		perror("socket() error");
		exit(0);
	}

	return sockfd;
}

int Inet_pton(int af, const char *src, void *dst)
{
	int ret;
	ret = inet_pton(af, src, dst);

	if(ret != 1){
		perror("inet_pton() error");
		exit(0);
	}
	return ret;
}

int Bind(int sockfd, const struct sockaddr *addr,
		socklen_t addrlen)
{
	int ret;
	ret = bind(sockfd, addr, addrlen);

	if(ret != 0){
		perror("bind() error");
		exit(0);
	}
	return ret;
}

int Listen(int sockfd, int backlog)
{
	int ret;
	ret = listen(sockfd, backlog);

	if(ret != 0){
		perror("listen() error");
		exit(0);
	}
	return ret;
}

int Accept(int sockfd, struct sockaddr *addr, socklen_t *addrlen)
{
	int connfd;
	connfd = accept(sockfd, addr, addrlen);

	if(connfd == -1){
		perror("accept() error");
		exit(0);
	}

	return connfd;
}

int Connect(int sockfd, const struct sockaddr *addr,
		socklen_t addrlen)
{
	int ret;
	ret = connect(sockfd, addr, addrlen);

	if(ret != 0){
		perror("connect() error");
		exit(0);
	}
	return ret;
}

pid_t Fork(void)
{
	pid_t pid;
	pid = fork();

	if(pid < 0){
		perror("fork() error");
		exit(0);
	}
	return pid;
}

int Setsockopt(int sockfd, int level, int optname,
				const void *optval, socklen_t optlen)
{
	int ret;
	ret = setsockopt(sockfd, level, optname, optval, optlen);

	if(ret == -1){
		perror("setsockopt() error");
		printf("%d\n", errno);
		exit(1);
	}

	return ret;
}

int Getsockopt(int sockfd, int level, int optname,
			void *optval, socklen_t *optlen)
{
	if(getsockopt(sockfd, level, optname, optval, optlen) == 0)
		return 0;

	perror("getsockopt() error");
	exit(1);
}

int TCP_connect(const char *ipaddr, const unsigned short port)
{
	int sockfd;
	sockfd = Socket(AF_INET, SOCK_STREAM, 0);

	struct sockaddr_in srvaddr;
	bzero(&srvaddr, sizeof srvaddr);
	srvaddr.sin_family = AF_INET;
	srvaddr.sin_port = htons(port);
	Inet_pton(AF_INET, ipaddr, &srvaddr.sin_addr);

	Connect(sockfd, (struct sockaddr *)&srvaddr, sizeof srvaddr);

	return sockfd;
}

int TCP_listen(const char *ipaddr, unsigned short port,
			int backlog, int *connfd, struct sockaddr *cliaddr,
			socklen_t *clilen)
{
	int sockfd;
	sockfd = Socket(AF_INET, SOCK_STREAM, 0);

	struct sockaddr_in srvaddr;
	bzero(&srvaddr, sizeof srvaddr);
	srvaddr.sin_family = AF_INET;
	srvaddr.sin_port = htons(port);

	if(ipaddr == NULL)
		srvaddr.sin_addr.s_addr = htonl(INADDR_ANY);
	else
		Inet_pton(AF_INET, ipaddr, &srvaddr.sin_addr);

	Bind(sockfd, (struct sockaddr *)&srvaddr, sizeof srvaddr);

	Listen(sockfd, backlog);
		
	*connfd = Accept(sockfd, cliaddr, clilen);

	return sockfd;
}

ssize_t Read(int fd, void *buf, size_t count)
{
	int nread;
	while((nread=read(fd, buf, count)) == -1 && errno == EINTR);
	
	if(nread == -1){
		perror("read() error");
		exit(1);
	}

	return nread;
}

ssize_t Write(int fd, const void *buf, size_t count)
{
	ssize_t ret = 0, total = 0;

	while(count > 0){
		while((ret=write(fd, buf+total, count)) == -1
				&& errno == EINTR);
		if(ret == -1){
			perror("write() error");
			exit(1);
		}

		count -= ret;
		total += ret;
	}
	
	return total;
}
/*

int Poll(struct pollfd *client, nfds_t nfds, int timeout)
{
	int nready;
	while(1){
		nready = poll(client, nfds, timeout);

		if(nready == -1 && errno != EINTR){
			perror("poll() error");
			exit(0);
		}

		else if(nready == -1 && errno == EINTR)
			 continue;
			
		else if(nready > 0)
			return nready;
	}
}
*/

int Select(int nfds, fd_set *rset, fd_set *wset,
			fd_set *eset, struct timeval *timeout)
{
	int ret;
	ret = select(nfds, rset, wset, eset, timeout);
	if(ret < 0){
		perror("select() error");
		exit(1);
	}
	return ret;
}

最后再顺便贴出这个srv.c 和 cli.c

cli.c:

#include "sock.h"

#define MAXSIZE 100

int main(void)
{
	int fd;
	fd = Socket(AF_INET, SOCK_STREAM, 0); // TCP socket

	struct sockaddr_in srvaddr;
	bzero(&srvaddr, sizeof srvaddr);

	srvaddr.sin_family = AF_INET;
	srvaddr.sin_port = htons(50001);
	Inet_pton(AF_INET, "127.0.0.1", &srvaddr.sin_addr);

	Connect(fd, (struct sockaddr *)&srvaddr, sizeof srvaddr);

	char buf[MAXSIZE];
	while(1)
	{
		bzero(buf, MAXSIZE);
		fgets(buf, MAXSIZE, stdin);
		write(fd, buf, strlen(buf));
	}

	return 0;
}

srv.c:

#include "sock.h"

#define MAXSIZE 100

int main(void)
{
	int fd;
	fd = Socket(AF_INET, SOCK_STREAM, 0);

	struct sockaddr_in srvaddr;
	bzero(&srvaddr, sizeof srvaddr);

	srvaddr.sin_family = AF_INET;
	srvaddr.sin_port = htons(50001);
	Inet_pton(AF_INET, "127.0.0.1", &srvaddr.sin_addr);

	Bind(fd, (struct sockaddr *)&srvaddr, sizeof srvaddr);

	Listen(fd, 5);

	int connfd = Accept(fd, NULL, NULL);

	char recv[MAXSIZE];
	while(1)
	{
		bzero(recv, MAXSIZE);
		if(read(connfd, recv, MAXSIZE-1) <= 0)
			break;
		write(STDOUT_FILENO, recv, strlen(recv));
	}

	return 0;
}