更多网络程序设计的文章见：目录
recv、send
ssize_t recv_peek(int sockfd, void *buf, size_t len)//与原型相比去掉了flags
{//可以从套接口接收数据，可以指定不将缓冲区数据移除
while(1)
{
int ret = recv(sockfd, buf, len, MSG_PEEK);
if(ret == -1 && errno == EINTR)
continue;
return ret;
}
}
readline实现
//暗含读取方法，标准是一个个读取，但效率太低，因此用偷窥的方法
//recv_peek不可重入
ssize_t readline(int sockfd, void *buf, size_t maxline)
{
int ret;
int nread;
char *bufp = buf;
int nleft = maxline;
while(1)
{
ret = recv_peek(sockfd, bufp, nleft);
if(ret < 0)
return ret;
else if(ret == 0)
return ret;//对方关闭了套接口
nread = ret;
int i;
for(i = 0; i < nread; i++)//最简单情况，有一条消息，我们读走
{
if(bufp[i] == '\n')
{
ret = readn(sockfd, bufp, i + 1);
if(ret != i+1)
exit(EXIT_FAILURE);
return ret;
}
}
if(nread > nleft)
exit(EXIT_FAILURE);
nleft -= nread;
ret = readn(sockfd, bufp, nread);
if(ret != nread)
exit(EXIT_FAILURE);
bufp += nread;
}
return -1;
}
用readline实现回射客户/服务器
- echosrv.c
#include<unistd.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <signal.h>//信号，进程间通信
#include <stdlib.h>
#include <stdio.h>
#include <errno.h>
#include <string.h>
#define ERR_EXIT(m) \
do\
{\
perror(m);\
exit(EXIT_FAILURE);\
}while (0)
ssize_t readn(int fd, void *buf, size_t count)
{
size_t nleft = count;
ssize_t nread;
char *bufp = (char*)buf;
while(nleft > 0)
{
if((nread = read(fd, bufp, nleft)) < 0)
{
if(errno == EINTR)
continue;
return -1;
}
else if(nread == 0)
return count - nleft;
bufp += nread;
nleft -= nread;
}
return count;
}
ssize_t writen(int fd, const void *buf, size_t count)
{
size_t nleft = count;
ssize_t nwritten;
char *bufp = (char*)buf;
while(nleft > 0)
{
if((nwritten = write(fd, bufp, nleft)) < 0)
{
if(errno == EINTR)
continue;
return -1;
}
else if(nwritten == 0)
continue;
bufp += nwritten;
nleft -= nwritten;
}
return count;
}
ssize_t recv_peek(int sockfd, void *buf, size_t len)//与原型相比去掉了flags
{//可以从套接口接收数据，可以指定不将缓冲区数据移除
while(1)
{
int ret = recv(sockfd, buf, len, MSG_PEEK);
if(ret == -1 && errno == EINTR)
continue;
return ret;
}
}
//暗含读取方法，标准是一个个读取，但效率太低，因此用偷窥的方法
//recv_peek不可重入
ssize_t readline(int sockfd, void *buf, size_t maxline)
{
int ret;
int nread;
char *bufp = buf;
int nleft = maxline;
while(1)
{
ret = recv_peek(sockfd, bufp, nleft);
if(ret < 0)
return ret;
else if(ret == 0)
return ret;//对方关闭了套接口
nread = ret;
int i;
for(i = 0; i < nread; i++)//最简单情况，有一条消息，我们读走
{
if(bufp[i] == '\n')
{
ret = readn(sockfd, bufp, i + 1);
if(ret != i+1)
exit(EXIT_FAILURE);
return ret;
}
}
if(nread > nleft)
exit(EXIT_FAILURE);
nleft -= nread;
ret = readn(sockfd, bufp, nread);
if(ret != nread)
exit(EXIT_FAILURE);
bufp += nread;
}
return -1;
}
void do_service(int conn)
{
char recvbuf[1024];
while(1)
{
memset(recvbuf, 0,sizeof(recvbuf));
int ret = readline(conn, recvbuf, 1024);
if(ret == -1)
ERR_EXIT("readline");
if(ret == 0)
{
printf("client close\n");
break;
}
fputs(recvbuf, stdout);
writen(conn, recvbuf, strlen(recvbuf));
}
}
int main(void)
{
int listenfd;//被动套接字
if((listenfd = socket(PF_INET,SOCK_STREAM,IPPROTO_TCP))<0)//创建套接字小于0表示失败
/* if((listenfd = socket(PF_INET,SOCK_STREAM,0))<0);*///让内核自己选定协议
ERR_EXIT("socket");
struct sockaddr_in servaddr;
memset(&servaddr,0,sizeof(servaddr));
servaddr.sin_family = AF_INET;
servaddr.sin_port = htons(5188);
servaddr.sin_addr.s_addr = htonl(INADDR_ANY);//定义IP地址INTADDR_ANY这个的意思是本机全部地址（推荐）
//第二种方法
//servaddr.sin_addr.s_addr = inet_addr("127.0.0.1");//定义IP地址
//第三种方式
//inet_aton("10.18.95.29",&servaddr.sin_addr);
int on = 1;//开启地址重复利用
if(setsockopt(listenfd,SOL_SOCKET,SO_REUSEADDR,&on,sizeof(on))<0)
ERR_EXIT("setsockopt");
if(bind(listenfd,(struct sockaddr*)&servaddr,sizeof(servaddr))<0)
ERR_EXIT("bind");
if(listen(listenfd,SOMAXCONN)<0)//监听后变为被动套接字
ERR_EXIT("listen");
struct sockaddr_in peeraddr;
socklen_t peerlen = sizeof(peeraddr);
int conn;//主动套接字
if((conn = accept(listenfd,(struct sockaddr*)&peeraddr,&peerlen))<0)
ERR_EXIT("accept");
pid_t pid;//父进程用来获取数据，子进程用来发送数据
while(1)
{
if((conn = accept(listenfd,(struct sockaddr*)&peeraddr,&peerlen)) < 0)
ERR_EXIT("accept");
printf("ip=%s,port=%d\n",inet_ntoa(peeraddr.sin_addr),ntohs(peeraddr.sin_port));
pid = fork();
if(pid == -1)
ERR_EXIT("fork");
if(pid == 0)
{
close(listenfd);
do_service(conn);
exit(EXIT_SUCCESS);
}
else
close(conn);
}
return 0;
}
- echocli.c
#include <sys/types.h>
#include <sys/socket.h>
#include <stdio.h>
#include <unistd.h>
#include <netinet/in.h>
#include <errno.h>
#include <stdlib.h>
#include <string.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#define ERR_EXIT(m) \
do \
{ \
perror(m); \
exit(EXIT_FAILURE); \
}while(0)
ssize_t readn(int fd, void *buf, size_t count)
{
size_t nleft = count;
ssize_t nread;
char *bufp = (char*)buf;
while(nleft > 0)
{
if((nread = read(fd, bufp, nleft)) < 0)
{
if(errno == EINTR)
continue;
return -1;
}
else if(nread == 0)
return count - nleft;
bufp += nread;
nleft -= nread;
}
return count;
}
ssize_t writen(int fd, const void *buf, size_t count)
{
size_t nleft = count;
ssize_t nwritten;
char *bufp = (char*)buf;
while(nleft > 0)
{
if((nwritten = write(fd, bufp, nleft)) < 0)
{
if(errno == EINTR)
continue;
return -1;
}
else if(nwritten == 0)
continue;
bufp += nwritten;
nleft -= nwritten;
}
return count;
}
ssize_t recv_peek(int sockfd, void *buf, size_t len)//与原型相比去掉了flags
{//可以从套接口接收数据，可以指定不将缓冲区数据移除
while(1)
{
int ret = recv(sockfd, buf, len, MSG_PEEK);
if(ret == -1 && errno == EINTR)
continue;
return ret;
}
}
//暗含读取方法，标准是一个个读取，但效率太低，因此用偷窥的方法
//recv_peek不可重入
ssize_t readline(int sockfd, void *buf, size_t maxline)
{
int ret;
int nread;
char *bufp = buf;
int nleft = maxline;
while(1)
{
ret = recv_peek(sockfd, bufp, nleft);
if(ret < 0)
return ret;
else if(ret == 0)
return ret;//对方关闭了套接口
nread = ret;
int i;
for(i = 0; i < nread; i++)//最简单情况，有一条消息，我们读走
{
if(bufp[i] == '\n')
{
ret = readn(sockfd, bufp, i + 1);
if(ret != i+1)
exit(EXIT_FAILURE);
return ret;
}
}
if(nread > nleft)
exit(EXIT_FAILURE);
nleft -= nread;
ret = readn(sockfd, bufp, nread);
if(ret != nread)
exit(EXIT_FAILURE);
bufp += nread;
}
return -1;
}
int main(void)
{
int sock;//创建一个套接字，与文件描述符相似。
if((sock = socket(PF_INET,SOCK_STREAM,IPPROTO_TCP)) < 0)
{//创建套接字，成功返回套接字，失败返回-1
ERR_EXIT("socket");
}
//地址初始化
struct sockaddr_in servaddr;//定义IPV4套接字地址
memset(&servaddr,0,sizeof(servaddr));//初始化地址
servaddr.sin_family = AF_INET; //定义地址家族
servaddr.sin_port = htons(5188);//定义端口号
//servaddr.sin_addr.s_addr = htonl(INADDR_ANY);//定义IP地址INTADDR_ANY这个的意思是本机全部地址,但服务器和客户端一般不在一台主机
//第二种方法
servaddr.sin_addr.s_addr = inet_addr("127.0.0.1");//定义IP地址
if(connect(sock,(struct sockaddr*)&servaddr,sizeof(servaddr)) < 0)//连接函数
{
ERR_EXIT("connect");
}
struct sockaddr_in localaddr;
socklen_t addrlen = sizeof(localaddr);
if(getsockname(sock, (struct sockaddr*)&localaddr, &addrlen) < 0)
ERR_EXIT("getsockname");
printf("ip=%s,port=%d\n", inet_ntoa(localaddr.sin_addr),ntohs(localaddr.sin_port));
char sendbuf[1024] = {0};
char recvbuf[1024] = {0};
while(fgets(sendbuf, sizeof(sendbuf), stdin) != NULL)//通信细节
{
writen(sock, sendbuf, strlen(sendbuf));
int ret = readline(sock, &recvbuf, sizeof(recvbuf));
if(ret == -1)
ERR_EXIT("readline");
else if(ret == 0)
{
printf("client_close\n");
break;
}
fputs(recvbuf, stdout);
memset(sendbuf, 0, sizeof(sendbuf));
memset(recvbuf, 0, sizeof(recvbuf));
}
close(sock);
return 0;
}
getsockname
- getsockname
struct sockaddr_in localaddr;
socklen_t addrlen = sizeof(localaddr);
if(getsockname(sock, (struct sockaddr*)&localaddr, &addrlen) < 0)
ERR_EXIT("getsockname");
printf("ip=%s,port=%d\n", inet_ntoa(localaddr.sin_addr),ntohs(localaddr.sin_port));
gethostname、gethostbyname
#include <unistd.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <netdb.h>
#include <stdio.h>
#include <errno.h>
#include <stdlib.h>
#include <string.h>
#define ERR_EXIT(m) \
do \
{ \
perror(m); \
exit(EXIT_FAILURE); \
}while(0)
int getlocalip(char *ip)
{
char host[100] = {0};
if(gethostname(host, sizeof(host)) < 0)
return -1;
struct hostent *hp;
if((hp = gethostbyname(host)) == NULL)
return -1;
strcpy(ip, inet_ntoa(*(struct in_addr*)hp->h_addr));
return 0;
}
int main(void)
{
char host[100] = {0};
if(gethostname(host, sizeof(host)) < 0)
ERR_EXIT("gethostname");
struct hostent *hp;
if((hp = gethostbyname(host)) == NULL)
ERR_EXIT("gethostbyname");
int i = 0;
while((hp->h_addr_list[i]) != NULL)
{
printf("%s\n", inet_ntoa(*(struct in_addr*)hp->h_addr_list[i]));
i++;
}
char ip[16] = {0};
getlocalip(ip);
printf("localip=%s\n", ip);
return 0;
}