Question

下面是一个名为Marvin的聊天客户端片段，如果有人说“Hey Marvin，1 + 1”，该程序将发送到服务器“Hey user ，2” 。问题是，即使输出可以正确打印客户端大小，当我尝试使用write（）将其发送到服务器时，服务器只会得到“Marvin：”

关于为什么我的写（）不起作用的任何想法？我突出显示了我使用写入的区域，但它们位于第二个功能中，位于中途。有很多辅助函数，所以我把它们剪掉并解释了它们通常做的事情。

static int sockfd;

int main(int argc, char **argv) {
    if (argc < 2) {
        fprintf(stderr, "usage: %s hostname [port number] ...\n", argv[0]);
        return(1);
    }

    //INITIALIZERS
    //int sockfd;
    fd_set master;
    char buf[500];
    struct hostent *hp;
    struct sockaddr_in peer;
    char *name = malloc(MAXHANDLE);
    char *todo = malloc(MAXMESSAGE); /*
    extern void reply(char *buf, char *name);
    extern char *myreadline(struct client *p);
    struct client *p = malloc(sizeof(struct client));
    extern int tracer(char *str, int start, int len);
    extern int choice(int nfds, fd_set *readfds, fd_set *writefds,
            fd_set *exceptfds, struct timeval *timeout);
    */
    //HOST
    if ((hp = gethostbyname(argv[1])) == NULL) {
        fprintf(stderr, "%s: no such host\n", argv[1]);
        return(1);
    }

    if (hp->h_addr_list[0] == NULL || hp->h_addrtype != AF_INET) {
        fprintf(stderr, "%s: not an internet protocol host name\n", argv[1]);
        return(1);
    }

    //SOCKET
    if ((sockfd = socket(AF_INET, SOCK_STREAM, 0)) < 0) {
        perror("socket");
        exit(1);
    }
    memset(&peer, '\0', sizeof peer);
    peer.sin_family = AF_INET;
    peer.sin_addr.s_addr = INADDR_ANY;

    //PORT
    if (argc > 2) {
        if (!(port = atoi(argv[2])) == 0) {
            peer.sin_port = htons(port);
        } else {
            fprintf(stderr, "%s: port number must be a positive integer\n", argv[0]);
            return(1);
        }
    } else {
        peer.sin_port = htons(1234);
    }

    //SOCKET
    peer.sin_addr = *((struct in_addr*)(hp->h_addr));
    if (connect(sockfd, (struct sockaddr *)&peer, sizeof(peer)) == -1) {
        perror("connect");
        close(sockfd);
        exit(1);
    }

    FD_ZERO(&master);
    FD_SET(STDIN_FILENO, &master);
    FD_SET(sockfd, &master);
    fd_set fds;

    //BANNER HANDLE
    //FILLS *p WITH INFORMATION of server
    //*p = addclient(sockfd);
    char *buff = malloc(500);
    while (1) {
        //READS A LINE
        //buff = myreadline(p);
        if (buff == NULL)
            continue;
        if (!strcmp(buff, CHATSVR_ID_STRING)) {
            write(sockfd, "Marvin", MAXHANDLE);
            break;
        } else {
            fprintf(stderr, "%s: invalid chatsvr\n", buff);
            exit(1);
        }
    }

    //LOOP
    while(1) {
        fds = master;
        //RUNS SELECT WITH ERROR CHECKING
        choice(sockfd+1, &fds, NULL, NULL, NULL);
        if(FD_ISSET(STDIN_FILENO, &fds)) {
            fgets(buf, sizeof buf, stdin);
            if (strlen(buf) > 0) {
                reply(buf, "Marvin");
            }
        } else if (FD_ISSET(sockfd, &fds)) {
            //name = myreadline(p);
            if (name != NULL) {
                printf("%s\n", name);
                strtok_r(name, ": ", &todo);
                //tracer(todo, 0, 1);
                reply(todo, name);
            }
        }
    }
    return(0);
}

//Given name and command, prints required output
void reply(char *buf, char *name) {
    //extern int tracer(char *str, int start, int len);
    //extern int tinder(const char *a, const char *b);
    char *replied = buf;

    if (strlen(buf) > 0) {
        if (!tinder(buf, "Hey Marvin,")) {
            printf("%s\n", replied);
            //ISSUE HERE XXX
            write(sockfd, replied, sizeof(replied));
            return;
        } else {
            tracer(buf, 0, 11);
        }
        struct expr *e = parse(buf);
        if (e) {
            sprintf(replied, "Marvin: Hey %s, %d\n", name, evalexpr(e));
            printf("%s\n", replied);
            //ISSUE HERE
            write(sockfd, replied, sizeof(replied));
            freeexpr(e);
        } else {
            sprintf(replied, "Marvin: Hey %s, I don't like that.\n[%s]\n", name, errorstatus);
            printf("%s\n", replied);
            //XXX ISSUE HERE
            write(sockfd, replied, sizeof(replied));
        }
   }
}

从客户端，我发送：

chatsvr: Welcome to our new participant, Marvin
hi
dsha
^C

服务器端，这就是显示的内容：

chatsvr: Welcome to our new participant, Marvin
Marvin:
Marvin:
Marvin:
chatsvr: Goodbye, Marvin

应该是：

chatsvr: Welcome to our new participant, Marvin
Marvin: hi
Marvin: dsha
chatsvr: Goodbye, Marvin

Answer 1

//ISSUE HERE XXX
write(sockfd, replied, sizeof(replied));

您应该使用strlen(replied)代替sizeof。

确保在将接收的字符串作为字符串使用之前将其终止。

写入服务器什么也不返回

1 个答案: