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/* J. David's webserver *//* This is a simple webserver. * Created November 1999 by J. David Blackstone. * CSE 4344 (Network concepts), Prof. Zeigler * University of Texas at Arlington *//* This program compiles for Sparc Solaris 2.6. * To compile for Linux: * 1) Comment out the #includeline. * 2) Comment out the line that defines the variable newthread. * 3) Comment out the two lines that run pthread_create(). * 4) Uncomment the line that runs accept_request(). * 5) Remove -lsocket from the Makefile. */#include #include #include #include #include #include #include #include #include #include #include #include #include #define ISspace(x) isspace((int)(x))#define SERVER_STRING "Server: jdbhttpd/0.1.0\r\n"void accept_request(int);void bad_request(int);void cat(int, FILE *);void cannot_execute(int);void error_die(const char *);void execute_cgi(int, const char *, const char *, const char *);int get_line(int, char *, int);void headers(int, const char *);void not_found(int);void serve_file(int, const char *);int startup(u_short *);void unimplemented(int);/**********************************************************************//* A request has caused a call to accept() on the server port to * return. Process the request appropriately. * Parameters: the socket connected to the client *//**********************************************************************/void accept_request(int client){ char buf[1024]; int numchars; char method[255]; char url[255]; char path[512]; size_t i, j; struct stat st; int cgi = 0; /* becomes true if server decides this is a CGI * program */ char *query_string = NULL; numchars = get_line(client, buf, sizeof(buf)); i = 0; j = 0; // 第一个空格前面的字符是http method while (!ISspace(buf[j]) && (i < sizeof(method) - 1)) { method[i] = buf[j]; i++; j++; } method[i] = '\0';// 只支持get和post if (strcasecmp(method, "GET") && strcasecmp(method, "POST")) { unimplemented(client); return; } // post方法则执行cgi程序处理 if (strcasecmp(method, "POST") == 0) cgi = 1; i = 0; // 跳过method后面的空格 while (ISspace(buf[j]) && (j < sizeof(buf))) j++;// 接着是url while (!ISspace(buf[j]) && (i < sizeof(url) - 1) && (j < sizeof(buf))) { url[i] = buf[j]; i++; j++; } url[i] = '\0';// 是get方法，则解析查询参数 if (strcasecmp(method, "GET") == 0) { query_string = url; // 遍历url直接找到?字符或找到字符串末尾 while ((*query_string != '?') && (*query_string != '\0')) query_string++; // 如果有查询参数则解析 if (*query_string == '?') { // 有查询参数说明需要cgi处理，即不是简单的文件读取请求 cgi = 1; // 把?替换为字符串结束符，即url变量里存的的字符串不包括查询参数 *query_string = '\0'; // 指向查询参数的第一个字符 query_string++; } } // 文件路径htdocs下 sprintf(path, "htdocs%s", url); // 最后一个字符是/说明是个目录，则取该目录下的index.html文件 if (path[strlen(path) - 1] == '/') strcat(path, "index.html"); // 找不到该文件返回404 if (stat(path, &st) == -1) { while ((numchars > 0) && strcmp("\n", buf)) /* read & discard headers */ numchars = get_line(client, buf, sizeof(buf)); not_found(client); } else { // 是个目录 if ((st.st_mode & S_IFMT) == S_IFDIR) strcat(path, "/index.html"); // 是可执行文件则说明是cgi程序 if ((st.st_mode & S_IXUSR) || (st.st_mode & S_IXGRP) || (st.st_mode & S_IXOTH) ) cgi = 1; // 返回静态文件给客户端 if (!cgi) serve_file(client, path); else // 执行cgi程序 execute_cgi(client, path, method, query_string); } close(client);}/**********************************************************************//* Inform the client that a request it has made has a problem. * Parameters: client socket *//**********************************************************************/void bad_request(int client){ char buf[1024]; sprintf(buf, "HTTP/1.0 400 BAD REQUEST\r\n"); send(client, buf, sizeof(buf), 0); sprintf(buf, "Content-type: text/html\r\n"); send(client, buf, sizeof(buf), 0); sprintf(buf, "\r\n"); send(client, buf, sizeof(buf), 0); sprintf(buf, " 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);}/**********************************************************************//* Put the entire contents of a file out on a socket. This function * is named after the UNIX "cat" command, because it might have been * easier just to do something like pipe, fork, and exec("cat"). * Parameters: the client socket descriptor * FILE pointer for the file to cat *//**********************************************************************/void cat(int client, FILE *resource){ char buf[1024]; fgets(buf, sizeof(buf), resource); while (!feof(resource)) { send(client, buf, strlen(buf), 0); fgets(buf, sizeof(buf), resource); }}/**********************************************************************//* 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){ char buf[1024]; int cgi_output[2]; int cgi_input[2]; pid_t pid; int status; int i; char c; int numchars = 1; int content_length = -1; buf[0] = 'A'; buf[1] = '\0'; 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); // 获取两个匿名管道 if (pipe(cgi_output) < 0) { cannot_execute(client); return; } if (pipe(cgi_input) < 0) { cannot_execute(client); return; } // fork进程 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]; // 先断开文件描述符1和标准输出file结构的关联，然后使1指向cgi_ouput[1]指向的file结构 dup2(cgi_output[1], 1); dup2(cgi_input[0], 0); // 关闭读端 close(cgi_output[0]); // 关闭写端 close(cgi_input[1]); // 输入参数给处理请求的cgi进程使用 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); } // 执行cgi进程 execl(path, path, NULL); exit(0); } else { /* parent */ close(cgi_output[1]); close(cgi_input[0]); if (strcasecmp(method, "POST") == 0) for (i = 0; i < content_length; i++) { /* 读数据然后写入写端cgi_input[1]，对端是子进程的cgi_input[0]，作为子进程的标准读入， 即子进程可以读到这里写入的数据 */ recv(client, &c, 1, 0); write(cgi_input[1], &c, 1); } /* 等待子进程写入，然后返回给客户端，cgi_output[1]是子进程的标准输出端， 从cgi_output[1]写入的数据可以从cgi_output[0]读取 */ while (read(cgi_output[0], &c, 1) > 0) send(client, &c, 1, 0); // 关闭管道 close(cgi_output[0]); close(cgi_input[1]); // 等到子进程退出 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) *//**********************************************************************/// 读取最多size字节到buf变量里int get_line(int sock, char *buf, int size){ int i = 0; char c = '\0'; int n;// 还没读够并且还没有读到换行符 while ((i < size - 1) && (c != '\n')) { // 读一个字节 n = recv(sock, &c, 1, 0); /* DEBUG printf("%02X\n", c); */ // 读取成功 if (n > 0) { // 处理\r\n \r的情况 if (c == '\r') { // \r的时候预读一个字节，该字节不从tcp缓存中删除 n = recv(sock, &c, 1, MSG_PEEK); /* DEBUG printf("%02X\n", c); */ // 读取成功并且是\n则进行真正的读取操作，为了消耗掉\n这个字节 if ((n > 0) && (c == '\n')) recv(sock, &c, 1, 0); else // 后面不是\n则也当做遇到了换行处理，即\r也是换行 c = '\n'; } buf[i] = c; i++; } else // 读取失败就直接当换行处理 c = '\n'; } buf[i] = '\0'; return(i);}/**********************************************************************//* Return the informational HTTP headers about a file. *//* Parameters: the socket to print the headers on * the name of the file *//**********************************************************************/// 发送http头void headers(int client, const char *filename){ char buf[1024]; (void)filename; /* could use filename to determine file type */ strcpy(buf, "HTTP/1.0 200 OK\r\n"); send(client, buf, strlen(buf), 0); strcpy(buf, SERVER_STRING); send(client, buf, strlen(buf), 0); sprintf(buf, "Content-Type: text/html\r\n"); send(client, buf, strlen(buf), 0); strcpy(buf, "\r\n"); send(client, buf, strlen(buf), 0);}/**********************************************************************//* Give a client a 404 not found status message. *//**********************************************************************/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, "
Not Found \r\n"); send(client, buf, strlen(buf), 0); sprintf(buf, "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, "\r\n"); send(client, buf, strlen(buf), 0);}/**********************************************************************//* Send a regular file to the client. Use headers, and report * errors to client if they occur. * Parameters: a pointer to a file structure produced from the socket * file descriptor * the name of the file to serve *//**********************************************************************/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)) /* read & discard headers */ numchars = get_line(client, buf, sizeof(buf)); resource = fopen(filename, "r"); if (resource == NULL) not_found(client); else { headers(client, filename); // 读取一个文件输出到客户端 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 *//**********************************************************************/// 传统的服务器启动流程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); // 绑定一个地址到socket，没有的话ip是本机地址，端口随机 if (bind(httpd, (struct sockaddr *)&name, sizeof(name)) < 0) error_die("bind"); if (*port == 0) /* if dynamically allocating a port */ { int namelen = sizeof(name); // 获取socket绑定的地址信息 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);}/**********************************************************************//* Inform the client that the requested web method has not been * implemented. * Parameter: the client socket *//**********************************************************************/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, "
Method Not Implemented\r\n"); send(client, buf, strlen(buf), 0); sprintf(buf, " \r\n"); send(client, buf, strlen(buf), 0); sprintf(buf, "HTTP request method not supported.\r\n"); send(client, buf, strlen(buf), 0); sprintf(buf, "\r\n"); send(client, buf, strlen(buf), 0);}/**********************************************************************/int main(void){ int server_sock = -1; u_short port = 0; int client_sock = -1; struct sockaddr_in client_name; int client_name_len = sizeof(client_name); pthread_t newthread;// 拿到一个监听的文件描述符 server_sock = startup(&port); printf("httpd running on port %d\n", port); while (1) { // 等待连接到来 client_sock = accept(server_sock, (struct sockaddr *)&client_name, &client_name_len); if (client_sock == -1) error_die("accept"); /* accept_request(client_sock); */ // 每一个连接用一个线程处理，主函数是accept_request if (pthread_create(&newthread , NULL, accept_request, client_sock) != 0) perror("pthread_create"); }// 服务器退出 close(server_sock); return(0);}
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