一个网络服务程序报errno 22的情况

来源：互联网发布：电信美洲卡网络制式编辑：程序博客网时间：2024/06/14 14:30

最近在学习写socket程序，然后就写了一个模拟web服务器的应答程序，下面我上源码。

#include <sys/socket.h>#include <netinet/in.h>#include <arpa/inet.h>#include <assert.h>#include <stdio.h>#include <unistd.h>#include <stdlib.h>#include <errno.h>#include <string.h>#include <sys/stat.h>#include <sys/types.h>#include <fcntl.h>#define BUFFER_SIZE 1024static const char *status_line[2] = {"200 OK", "500 Internal server error"};int main(int argc, char *argv[]){        if(argc <= 3){                printf("usage: %s ip_address port_number filename\n", basename(argv[0]));                        return 1;        }        const char* ip = argv[1];        int port = atoi(argv[2]);        const char *file_name = argv[3];        struct sockaddr_in address;        bzero(&address, sizeof(address));        address.sin_family = AF_INET;        inet_pton(AF_INET, ip, &address.sin_addr);        address.sin_port = htons(port);        int sock = socket(PF_INET, SOCK_STREAM, 0);        assert(sock >= 0);        int ret = bind(sock, (struct sockaddr*)&address, sizeof(address));        assert(ret != -1);        struct sockaddr_in client;        socklen_t client_addrlength = sizeof(client);        int connfd = accept(sock, (struct sockaddr*)&client, &client_addrlength);        if(connfd < 0){                printf("errno is : %d\n", errno);        }else{                char header_buf[BUFFER_SIZE];                memset(header_buf, '\0', BUFFER_SIZE);                char *file_buf;                struct stat file_stat;                bool valid = true;                int len = 0;                if(stat(file_name, &file_stat) < 0){                        valid = false;                }else{                        if(S_ISDIR(file_stat.st_mode)){                                valid = false;                        }else if(file_stat.st_mode & S_IROTH){                                int fd = open(file_name, O_RDONLY);                                file_buf = new char[file_stat.st_size + 1];                                memset(file_buf, '\0', file_stat.st_size + 1);                                if(read(fd, file_buf, file_stat.st_size) < 0){                                        valid = false;                                }                        }else{                                valid = false;                        }                }                if(valid){                        ret = snprintf(header_buf, BUFFER_SIZE-1, "%s %s\r\n", "HTTP/1.1",                                status_line[0]);                        len += ret;                        ret = snprintf(header_buf + len, BUFFER_SIZE-1-len,                                "Content-Length: %d\r\n", file_stat.st_size);                        len += ret;                        ret = snprintf(header_buf + len, BUFFER_SIZE-1-len, "%s", "\r\n");                        struct iovec iv[2];                        iv[0].iov_base = header_buf;                        iv[0].iov_len = strlen(header_buf);                        iv[1].iov_base = file_buf;                        iv[1].iov_len = file_stat.st_size;                        ret = writev(connfd, iv, 2);                }else{                        ret = snprintf(header_buf, BUFFER_SIZE-1, "%s %s\r\n",                                "HTTP/1.1", status_line[1]);                        len += ret;                        ret = snprintf(header_buf + len, BUFFER_SIZE-1-len, "%s", "\r\n");                        send(connfd, header_buf, strlen(header_buf), 0);                }                close(connfd);                delete[] file_buf;        }        close(sock);        return 0;}

我编译运行之后，总是报errno 22的错误。

./writev 192.168.91.128 5555 count1.c

errno is : 22

因为这个实在accept的函数中打印出来了，我查了一下errno，说是参数错误，然后我就去翻accept的定义啊，看了很久，觉得没什么问题啊。

然后上 CSDN，也看到一个小伙伴报同样的错误，我就看了下他贴上来的源码，突然看到了listen，恍然大悟啊，我竟然在bind之后没有listen~~~~~~

可恶啊！！！

后来加上listen之后就没有问题了。

完整的源码：

#include <sys/socket.h>#include <netinet/in.h>#include <arpa/inet.h>#include <assert.h>#include <stdio.h>#include <unistd.h>#include <stdlib.h>#include <errno.h>#include <string.h>#include <sys/stat.h>#include <sys/types.h>#include <fcntl.h>#define BUFFER_SIZE 1024static const char *status_line[2] = {"200 OK", "500 Internal server error"};int main(int argc, char *argv[]){        if(argc <= 3){                printf("usage: %s ip_address port_number filename\n", basename(argv[0]));                        return 1;        }        const char* ip = argv[1];        int port = atoi(argv[2]);        const char *file_name = argv[3];        struct sockaddr_in address;        bzero(&address, sizeof(address));        address.sin_family = AF_INET;        inet_pton(AF_INET, ip, &address.sin_addr);        address.sin_port = htons(port);        int sock = socket(PF_INET, SOCK_STREAM, 0);        assert(sock >= 0);        int ret = bind(sock, (struct sockaddr*)&address, sizeof(address));        assert(ret != -1);        ret = listen(sock, 5);        assert(ret != -1);        struct sockaddr_in client;        socklen_t client_addrlength = sizeof(client);        int connfd = accept(sock, (struct sockaddr*)&client, &client_addrlength);        if(connfd < 0){                printf("errno is : %d\n", errno);        }else{                char header_buf[BUFFER_SIZE];                memset(header_buf, '\0', BUFFER_SIZE);                char *file_buf;                struct stat file_stat;                bool valid = true;                int len = 0;                if(stat(file_name, &file_stat) < 0){                        valid = false;                }else{                        if(S_ISDIR(file_stat.st_mode)){                                valid = false;                        }else if(file_stat.st_mode & S_IROTH){                                int fd = open(file_name, O_RDONLY);                                file_buf = new char[file_stat.st_size + 1];                                memset(file_buf, '\0', file_stat.st_size + 1);                                if(read(fd, file_buf, file_stat.st_size) < 0){                                        valid = false;                                }                        }else{                                valid = false;                        }                }                if(valid){                        ret = snprintf(header_buf, BUFFER_SIZE-1, "%s %s\r\n", "HTTP/1.1",                                status_line[0]);                        len += ret;                        ret = snprintf(header_buf + len, BUFFER_SIZE-1-len,                                "Content-Length: %d\r\n", file_stat.st_size);                        len += ret;                        ret = snprintf(header_buf + len, BUFFER_SIZE-1-len, "%s", "\r\n");                        struct iovec iv[2];                        iv[0].iov_base = header_buf;                        iv[0].iov_len = strlen(header_buf);                        iv[1].iov_base = file_buf;                        iv[1].iov_len = file_stat.st_size;                        ret = writev(connfd, iv, 2);                }else{                        ret = snprintf(header_buf, BUFFER_SIZE-1, "%s %s\r\n",                                "HTTP/1.1", status_line[1]);                        len += ret;                        ret = snprintf(header_buf + len, BUFFER_SIZE-1-len, "%s", "\r\n");                        send(connfd, header_buf, strlen(header_buf), 0);                }                close(connfd);                delete[] file_buf;        }        close(sock);        return 0;}

输出结果：

[root@localhost C]# telnet 192.168.91.128 5555Trying 192.168.91.128...Connected to 192.168.91.128.Escape character is '^]'.HTTP/1.1 200 OKContent-Length: 270#include <stdio.h>int main(){        int input;        int flag = 1;        int count = 0;        scanf("%d",&input);        printf("input is %d\n", input);        while(flag){                if(input & flag){                        count++;                }                flag <<= 1;        }        printf("the number has %d 1 in binary mode.\n", count);        return 0;}Connection closed by foreign host.

完！

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