操作系统 作业调度实验报告

Your browser sent a bad request, "); send(client, buf, sizeof(buf), 0); sprintf(buf, "such as a POST without a Content-Length.\r\n"); send(client, buf, sizeof(buf), 0); } /*! * @brief 将文件内容发送到网络客户端 * * @param[in] client 客户端套接字描述符 * @param[in] resource 文件指针（指向要发送的文件） */ void cat(int client, FILE *resource) { char buf[1024]; size_t bytes_read; while ((bytes_read = fread(buf, 1, sizeof(buf), resource)) > 0) { if (send(client, buf, bytes_read, 0) < bytes_read) { perror("send"); break; } } } /**********************************************************************/ /* Inform the client that a CGI script could not be executed. * Parameter: the client socket descriptor. */ /**********************************************************************/ void cannot_execute(int client) { char buf[1024]; sprintf(buf, "HTTP/1.0 500 Internal Server Error\r\n"); send(client, buf, strlen(buf), 0); sprintf(buf, "Content-type: text/html\r\n"); send(client, buf, strlen(buf), 0); sprintf(buf, "\r\n"); send(client, buf, strlen(buf), 0); sprintf(buf, "

Error prohibited CGI execution.\r\n"); send(client, buf, strlen(buf), 0); } /**********************************************************************/ /* Print out an error message with perror() (for system errors; based * on value of errno, which indicates system call errors) and exit the * program indicating an error. */ /**********************************************************************/ void error_die(const char *sc) { perror(sc); exit(1); } /**********************************************************************/ /* Execute a CGI script. Will need to set environment variables as * appropriate. * Parameters: client socket descriptor * path to the CGI script */ /**********************************************************************/ void execute_cgi(int client, const char *path, const char *method, const char *query_string) { // 缓冲区 char buf[1024]; int cgi_output[2]; int cgi_input[2]; pid_t pid; int status; int i = 0; char c; int numchars = 1; int content_length = -1; // 默认字符 buf[0] = 'A'; buf[1] = '\0'; // 忽略大小写比较字符串 if (strcasecmp(method, "GET") == 0) { while ((numchars > 0) && strcmp("\n", buf)) /* read & discard headers */ { numchars = get_line(client, buf, sizeof(buf)); } } else /* POST */ { numchars = get_line(client, buf, sizeof(buf)); while ((numchars > 0) && strcmp("\n", buf)) { buf[15] = '\0'; if (strcasecmp(buf, "Content-Length:") == 0) { content_length = atoi(&(buf[16])); } numchars = get_line(client, buf, sizeof(buf)); } if (content_length == -1) { bad_request(client); return; } } sprintf(buf, "HTTP/1.0 200 OK\r\n"); send(client, buf, strlen(buf), 0); /* 建立output管道 */ if (pipe(cgi_output) < 0) { cannot_execute(client); return; } /* 建立input管道 */ if (pipe(cgi_input) < 0) { cannot_execute(client); return; } if ((pid = fork()) < 0) { cannot_execute(client); return; } if (pid == 0) /* child: CGI script */ { char meth_env[255]; char query_env[255]; char length_env[255]; // 子进程输出重定向到output管道的1端 dup2(cgi_output[1], 1); // 子进程输入重定向到input管道的0端 dup2(cgi_input[0], 0); // 关闭无用管道口 close(cgi_output[0]); close(cgi_input[1]); // CGI环境变量 sprintf(meth_env, "REQUEST_METHOD=%s", method); putenv(meth_env); if (strcasecmp(method, "GET") == 0) { sprintf(query_env, "QUERY_STRING=%s", query_string); putenv(query_env); } else { /* POST */ sprintf(length_env, "CONTENT_LENGTH=%d", content_length); putenv(length_env); } // 替换执行path execl(path, path, NULL); // int m = execl(path, path, NULL); // 如果path有问题，例如将html网页改成可执行的，但是执行后m为-1 // 退出子进程，管道被破坏，但是父进程还在往里面写东西，触发Program received signal SIGPIPE, Broken pipe. exit(0); } else { /* parent */ close(cgi_output[1]); close(cgi_input[0]); if (strcasecmp(method, "POST") == 0) { for (i = 0; i < content_length; i++) { recv(client, &c, 1, 0); ssize_t bytes_written = write(cgi_input[1], &c, 1); if (bytes_written <= 0) { perror("Failed to write to CGI"); close(cgi_input[1]); close(cgi_input[0]); break; } } } while (read(cgi_output[0], &c, 1) > 0) { send(client, &c, 1, 0); } close(cgi_output[0]); close(cgi_input[1]); waitpid(pid, &status, 0); } } /**********************************************************************/ /* Get a line from a socket, whether the line ends in a newline, * carriage return, or a CRLF combination. Terminates the string read * with a null character. If no newline indicator is found before the * end of the buffer, the string is terminated with a null. If any of * the above three line terminators is read, the last character of the * string will be a linefeed and the string will be terminated with a * null character. * Parameters: the socket descriptor * the buffer to save the data in * the size of the buffer * Returns: the number of bytes stored (excluding null) */ /**********************************************************************/ // 得到一行数据,只要发现c为\n,就认为是一行结束，如果读到\r,再用MSG_PEEK的方式读入一个字符，如果是\n，从socket用读出 // 如果是下个字符则不处理，将c置为\n，结束。如果读到的数据为0中断，或者小于0，也视为结束，c置为\n /*! * @brief 从socket中获取一行数据 * * @param[in] sock socket * @param[in] buf 用于保存数据的缓冲区 * @param[in] size 缓冲区的大小 * @return int 存储的字节数 */ int get_line(int sock, char *buf, int size) { int i = 0; char c = '\0'; int n; while ((i < size - 1) && (c != '\n')) { n = recv(sock, &c, 1, 0); if (n > 0) { if (c == '\r') { n = recv(sock, &c, 1, MSG_PEEK); if ((n > 0) && (c == '\n')) { recv(sock, &c, 1, 0); } else { c = '\n'; } } buf[i] = c; i++; } else c = '\n'; } buf[i] = '\0'; return (i); } /*! * @brief 根据文件路径的扩展名返回对应的 MIME 类型 * * @param[in] path 路径字符串 * @return const char* */ const char *get_content_type(const char *path) { const char *ext = strrchr(path, '.'); if (ext) { if (strcasecmp(ext, ".css") == 0) { return "text/css"; } if (strcasecmp(ext, ".js") == 0) { return "application/javascript"; } if (strcasecmp(ext, ".png") == 0) { return "image/png"; } if (strcasecmp(ext, ".jpg") == 0 || strcasecmp(ext, ".jpeg") == 0) { return "image/jpeg"; } if (strcasecmp(ext, ".gif") == 0) { return "image/gif"; } if (strcasecmp(ext, ".ico") == 0) { return "image/x-icon"; } if (strcasecmp(ext, ".svg") == 0) { return "image/svg+xml"; } if (strcasecmp(ext, ".woff") == 0) { return "font/woff"; } if (strcasecmp(ext, ".woff2") == 0) { return "font/woff2"; } } return "text/html"; } /*! * @brief 发送HTTP响应头 * * @param[in] client 客户端 * @param[in] filename 文件名 */ void headers(int client, const char *filename) { char buf[1024]; const char *content_type = get_content_type(filename); sprintf(buf, "HTTP/1.0 200 OK\r\n"); send(client, buf, strlen(buf), 0); sprintf(buf, SERVER_STRING); send(client, buf, strlen(buf), 0); sprintf(buf, "Content-Type: %s\r\n", content_type); send(client, buf, strlen(buf), 0); sprintf(buf, "\r\n"); send(client, buf, strlen(buf), 0); } /*! * @brief 404 * * @param[in] client 客户端 */ void not_found(int client) { char buf[1024]; sprintf(buf, "HTTP/1.0 404 NOT FOUND\r\n"); send(client, buf, strlen(buf), 0); sprintf(buf, SERVER_STRING); send(client, buf, strlen(buf), 0); sprintf(buf, "Content-Type: text/html\r\n"); send(client, buf, strlen(buf), 0); sprintf(buf, "\r\n"); send(client, buf, strlen(buf), 0); sprintf(buf, "<HTML><TITLE>Not Found</TITLE>\r\n"); send(client, buf, strlen(buf), 0); sprintf(buf, "<BODY>

The server could not fulfill\r\n"); send(client, buf, strlen(buf), 0); sprintf(buf, "your request because the resource specified\r\n"); send(client, buf, strlen(buf), 0); sprintf(buf, "is unavailable or nonexistent.\r\n"); send(client, buf, strlen(buf), 0); sprintf(buf, "</BODY></HTML>\r\n"); send(client, buf, strlen(buf), 0); } /*! * @brief 如果不是CGI文件，直接读取文件返回给请求的http客户端 * * @param[in] client 客户端 * @param[in] filename 文件名 */ void serve_file(int client, const char *filename) { FILE *resource = NULL; int numchars = 1; char buf[1024]; buf[0] = 'A'; buf[1] = '\0'; while ((numchars > 0) && strcmp("\n", buf)) { numchars = get_line(client, buf, sizeof(buf)); } resource = fopen(filename, "rb"); if (resource == NULL) { not_found(client); } else { headers(client, filename); cat(client, resource); } fclose(resource); } /**********************************************************************/ /* This function starts the process of listening for web connections * on a specified port. If the port is 0, then dynamically allocate a * port and modify the original port variable to reflect the actual * port. * Parameters: pointer to variable containing the port to connect on * Returns: the socket */ /**********************************************************************/ int startup(u_short *port) { int httpd = 0; struct sockaddr_in name; httpd = socket(PF_INET, SOCK_STREAM, 0); if (httpd == -1) { error_die("socket"); } memset(&name, 0, sizeof(name)); name.sin_family = AF_INET; name.sin_port = htons(*port); name.sin_addr.s_addr = htonl(INADDR_ANY); if (bind(httpd, (struct sockaddr *)&name, sizeof(name)) < 0) { error_die("bind"); } if (*port == 0) { socklen_t namelen = sizeof(name); if (getsockname(httpd, (struct sockaddr *)&name, &namelen) == -1) { error_die("getsockname"); } *port = ntohs(name.sin_port); } if (listen(httpd, 5) < 0) { error_die("listen"); } return (httpd); } /*! * @brief 没有实现请求 * * @param[in] client 客户端 */ void unimplemented(int client) { char buf[1024]; sprintf(buf, "HTTP/1.0 501 Method Not Implemented\r\n"); send(client, buf, strlen(buf), 0); sprintf(buf, SERVER_STRING); send(client, buf, strlen(buf), 0); sprintf(buf, "Content-Type: text/html\r\n"); send(client, buf, strlen(buf), 0); sprintf(buf, "\r\n"); send(client, buf, strlen(buf), 0); sprintf(buf, "<HTML><HEAD><TITLE>Method Not Implemented\r\n"); send(client, buf, strlen(buf), 0); sprintf(buf, "</TITLE></HEAD>\r\n"); send(client, buf, strlen(buf), 0); sprintf(buf, "<BODY>

HTTP request method not supported.\r\n"); send(client, buf, strlen(buf), 0); sprintf(buf, "</BODY></HTML>\r\n"); send(client, buf, strlen(buf), 0); } int main(void) { int server_sock = -1; u_short port = 80; // 使用8080端口避免权限问题 struct sockaddr_in client_name; socklen_t client_name_len = sizeof(client_name); // 设置信号处理 signal(SIGPIPE, handle_sigpipe); server_sock = startup(&port); printf("HTTP server running on port %d\n", port); while (1) { int client_sock = accept(server_sock, (struct sockaddr *)&client_name, &client_name_len); if (client_sock == -1) { perror("accept failed"); continue; } pid_t pid = fork(); if (pid < 0) { perror("fork failed"); close(client_sock); } else if (0 == pid) { close(server_sock); accept_request(client_sock); exit(EXIT_SUCCESS); } else { close(client_sock); } } close(server_sock); return 0; } 实现以IO多路复用方式实现web server功能(必修) 要求尽可能少的修改代码，并列出要添加或者删除的部分