（P10）socket编程(五)：read，write与recv，send ，用readline实现回射客户/服务器 ，getsockname，getpeername ，gethostname

#include #include #include #include #include #include #include #include

using namespace std;//消息通过键盘输出，消息之间的边界就是/n，就不需要下面的结构体// struct packet// {// int len;// char buf[1024];// };

#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; // 剩余字节数 ssize_t nread; char *bufp = (char*) buf;

while (nleft > 0) { nread = read(fd, bufp, nleft); if (nread < 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){ while (1) { // recv有数据就返回，没有数据就阻塞 //若对方套接口关闭，则返回为0 //recv只能用于套接口 int ret = recv(sockfd, buf, len, MSG_PEEK); if (ret == -1 && errno == EINTR)//EINTR表示被信号中断 { continue; } return ret; }}

//readline只能用于套接口，因为使用了recv_peek函数ssize_t readline(int sockfd, void *buf, size_t maxline){ int ret; int nread; char *bufp = (char*)buf; // 当前指针位置 int nleft = maxline;//maxline一行最大的字节数，但是读取到\n就可以返回 while (1) { ret = recv_peek(sockfd, bufp, nleft);//这里只是偷窥了缓冲区的数据，但是没有移走 if (ret < 0) { return ret; } else if (ret == 0)//ret == 0表示对方关闭套接口 { return ret; } nread = ret;

//判断接收缓冲区是否有\n int i; for (i = 0; i < nread; i++) { if (bufp[i] == '\n')//若有\n，则将其作为一条消息读走 { ret = readn(sockfd, bufp, i+1);//将数据从缓冲区移除，读取到i，说明有i+1个数据，包括\n if (ret != i+1)//接收到的字节数不等于i+1,说明失败 { exit(EXIT_FAILURE); } return ret;//返回一条消息 } }

// 若没有\n，说明还不满一条消息，也需要将数据读出来，放到缓冲区bufp

if (nread > nleft)//从缓冲区读到的字节数要小于剩余字节数，否则有问题 { exit(EXIT_FAILURE); } nleft -= nread; ret = readn(sockfd, bufp, nread); if (ret != nread) { exit(EXIT_FAILURE); } bufp += nread;//指针偏移，将数据放到屁股后面 } return -1;}

void echo_srv(int connfd){ char recvbuf[1024];

int n; while (1) { memset(recvbuf, 0, sizeof recvbuf); int ret = readline(connfd, recvbuf, 1024);//按行接收到缓冲区 if (ret == -1) { ERR_EXIT("readline"); } if (ret == 0) { printf("client close\n"); break; }

fputs(recvbuf, stdout); writen(connfd, recvbuf, strlen(recvbuf)); }

}

int main(int argc, char** argv) { // 1. 创建套接字 int listenfd; if ((listenfd = socket(AF_INET, SOCK_STREAM, IPPROTO_TCP)) < 0) { ERR_EXIT("socket"); }

// 2. 分配套接字地址 struct sockaddr_in servaddr; memset(&servaddr, 0, sizeof servaddr); servaddr.sin_family = AF_INET; servaddr.sin_port = htons(6666); servaddr.sin_addr.s_addr = htonl(INADDR_ANY); // servaddr.sin_addr.s_addr = inet_addr("127.0.0.1"); // inet_aton("127.0.0.1", &servaddr.sin_addr);

int on = 1; // 确保time_wait状态下同一端口仍可使用 if (setsockopt(listenfd, SOL_SOCKET, SO_REUSEADDR, &on, sizeof on) < 0) { ERR_EXIT("setsockopt"); }

// 3. 绑定套接字地址 if (bind(listenfd, (struct sockaddr *) &servaddr, sizeof servaddr) < 0) { ERR_EXIT("bind"); } // 4. 等待连接请求状态 if (listen(listenfd, SOMAXCONN) < 0) { ERR_EXIT("listen"); } // 5. 允许连接 struct sockaddr_in peeraddr; socklen_t peerlen = sizeof peeraddr;

// 6. 数据交换 pid_t pid; while (1) { int connfd; if ((connfd = accept(listenfd, (struct sockaddr *) &peeraddr, &peerlen)) < 0) { ERR_EXIT("accept"); }

printf("id = %s, ", inet_ntoa(peeraddr.sin_addr)); printf("port = %d\n", ntohs(peeraddr.sin_port));

pid = fork();

if (pid == -1) { ERR_EXIT("fork"); } if (pid == 0) // 子进程 { close(listenfd); echo_srv(connfd); //printf("child exit\n"); exit(EXIT_SUCCESS); } else { //printf("parent exit\n"); close(connfd); }

} // 7. 断开连接 close(listenfd);

return 0;}