非阻塞版connect TCP回显C/S

客户端代码:

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <sys/socket.h>
#include <errno.h>
#include <string.h>
#include <fcntl.h>
#include <sys/select.h>
#include <netdb.h>

#define BUFSIZE 4096

int connect_nblock(int sockfd,struct sockaddr* to,socklen_t tolen) {
    int val;
    if ((val = fcntl(sockfd,F_GETFL,0)) < 0) {
        fprintf(stderr,"fcntl error: %s\n",strerror(errno));
        exit(1);
    }

    if (fcntl(sockfd,F_SETFL,val | O_NONBLOCK) < 0) {
        fprintf(stderr,"fcntl error: %s\n",strerror(errno));
        exit(1);
    }
    int n;
    if ((n = connect(sockfd,to,tolen)) < 0) {
        if (errno != EINPROGRESS) {
            return -1;
        }
    }

    if (n == 0) {
        if (fcntl(sockfd,F_SETFL,val) < 0) {
            fprintf(stderr,"fcntl error: %s\n",strerror(errno));
            exit(1);
        }
        return 0;
    }
    fd_set ws,rs;
    FD_ZERO(&ws);
    FD_ZERO(&rs);
    FD_SET(sockfd,&ws);
    FD_SET(sockfd,&rs);
    struct timeval tv;
    tv.tv_sec = 40;
    tv.tv_usec = 0;
    if (select(sockfd + 1,&rs,&ws,NULL,&tv) == 0) {
        return -1;
    }
    if (FD_ISSET(sockfd,&ws) || FD_ISSET(sockfd,&rs)) {
        struct sockaddr_storage peer;
        socklen_t len = sizeof(struct sockaddr_storage);
        if (getpeername(sockfd,(struct sockaddr*)&peer,&len) == ENOTCONN) {
            return -1;
        }else {
            if (fcntl(sockfd,F_SETFL,val) < 0) {
                fprintf(stderr,"fcntl error: %s\n",strerror(errno));
                exit(1);
            }
            return 0;
        }
    }else {
        return -1;
    }
}
void client_echo(int sockfd) {
    char send[BUFSIZE];
    int n;
    while ((n = read(STDIN_FILENO,send,BUFSIZE)) > 0) {
        if (write(sockfd,send,n) != n) {
            printf("write to socket error: %s\n",strerror(errno));
            exit(1);
        }
        if ((n = read(sockfd,send,n)) < 0) {
            printf("read on socket error: %s\n",strerror(errno));
            exit(1);
        }
        if (write(STDOUT_FILENO,send,n) != n) {
            printf("write to stdout error: %s\n",strerror(errno));
            exit(1);
        }
    }
}
int main(int argc,char** argv) {
    if (argc != 3) {
        printf("please check or add <ip address or host name> or <service name or port>\n");
        exit(1);
    }

    struct addrinfo hints;
    bzero(&hints,sizeof(struct addrinfo));

    hints.ai_flags = AI_ALL;
    hints.ai_family = AF_UNSPEC;
    hints.ai_socktype = SOCK_STREAM;
    hints.ai_protocol = IPPROTO_TCP;

    struct addrinfo* results;
    int err;
    if ((err = getaddrinfo(argv[1],argv[2],&hints,&results)) != 0) {
        printf("getaddrinfo error: %s\n",gai_strerror(err));
        exit(1);
    }

    struct addrinfo* dummy = results;
    int sockfd;
    for (; dummy != NULL; dummy = dummy->ai_next) {
        if ((sockfd = socket(dummy->ai_family,dummy->ai_socktype,dummy->ai_protocol)) < 0) {
            continue;
        }
        if (connect_nblock(sockfd,dummy->ai_addr,dummy->ai_addrlen) == 0) {
            break;
        }
        close(sockfd);
    }

    if (dummy == NULL) {
        printf("all socket failed\n");
        freeaddrinfo(results);
        exit(1);
    }
    freeaddrinfo(results);
    client_echo(sockfd);
    return 0;
}

服务端代码:

#include <stdio.h>
#include <stdlib.h>
#include <sys/socket.h>
#include <string.h>
#include <errno.h>
#include <unistd.h>
#include <netdb.h>
#include <sys/wait.h>

#define BUFSIZE 4096
#define LISTENQ 100

void sig_child(int signo) {
    int ppid;
    while ((ppid = waitpid(-1,NULL,WNOHANG)) > 0) {
        printf("child process: %d terminated\n",ppid);
    }
}

void server_echo(int fd) {
    char recv[BUFSIZE];
    int n;
    struct msghdr rvmsg;
    struct iovec io;
    struct sockaddr_storage from;
    struct cmsghdr control;
    io.iov_base = recv;
    io.iov_len = BUFSIZE;
    rvmsg.msg_name = &from;
    rvmsg.msg_iov = &io;
    rvmsg.msg_iovlen = 1;
    rvmsg.msg_control = &control;
    rvmsg.msg_controllen = sizeof(struct cmsghdr);
    struct msghdr sdmsg;
    while ((n = recvmsg(fd,&rvmsg,0)) > 0) {
        sdmsg.msg_name = rvmsg.msg_name;
        sdmsg.msg_namelen = rvmsg.msg_namelen;
        sdmsg.msg_iov = &io;
        sdmsg.msg_iovlen = 1;
        sdmsg.msg_control = NULL;
        sdmsg.msg_controllen = 0;
        sdmsg.msg_flags = 0;
        io.iov_len = n;
        if (sendmsg(fd,&sdmsg,0) != n) {
            printf("send message to client failed: %s\n",strerror(errno));
            exit(1);
        }
        io.iov_len = BUFSIZE;
    }
}
int main(int argc,char** argv) {
    if (argc != 2) {
        printf("please check <service name or port>\n");
        exit(1);
    }

    struct addrinfo hints;
    bzero(&hints,sizeof(struct addrinfo));
    hints.ai_flags = AI_PASSIVE;
    hints.ai_family = AF_UNSPEC;
    hints.ai_socktype = SOCK_STREAM;
    hints.ai_protocol = IPPROTO_TCP;

    struct addrinfo* results;
    int err;
    if ((err = getaddrinfo(NULL,argv[1],&hints,&results)) != 0) {
        printf("getaddrinfo error: %s\n",gai_strerror(err));
        exit(1);
    }
    struct addrinfo* dummy = results;
    int sockfd;
    for (; dummy != NULL; dummy = dummy->ai_next) {
        if ((sockfd = socket(dummy->ai_family,dummy->ai_socktype,dummy->ai_protocol)) < 0) {
            continue;
        }
        if (bind(sockfd,dummy->ai_addr,dummy->ai_addrlen) == 0) {
            break;
        }
        close(sockfd);
    }
    if (dummy == NULL) {
        freeaddrinfo(results);
        printf("all failed\n");
        exit(1);
    }
    freeaddrinfo(results);
    if (listen(sockfd,LISTENQ) < 0) {
        printf("listen error: %s\n",strerror(errno));
        exit(1);
    }
    int connfd;
    int pid;
    if (signal(SIGCHLD,sig_child) == SIG_ERR) {
        printf("signal error: %s\n",strerror(errno));
        exit(1);
    }
    for (; ;) {
        if ((connfd = accept(sockfd,NULL,NULL)) < 0) {
            if (errno == EINTR) {
                continue;
            }else {
                printf("accept error: %s\n",strerror(errno));
                exit(1);
            }
        }
        if ((pid = fork()) < 0) {
            printf("fork error: %s\n",strerror(errno));
            exit(1);
        }else if (pid == 0) {
            close(sockfd);
            server_echo(connfd);
            close(connfd);
            exit(0);
        }
        close(connfd);
    }
    return 0;
}