294 lines
9.0 KiB
C
294 lines
9.0 KiB
C
#include "common.h"
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void process_trans(int fd,int hit);
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void read_requesthdrs(rio_t *rp,int hit,int nrh);
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int is_static(char *uri);
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void parse_static_uri(char *uri, char *filename);
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void parse_dynamic_uri(char *uri, char *filename, char *cgiargs);
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void feed_static(int fd, char *filename, int filesize);
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void get_filetype(char *filename, char *filetype);
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void feed_dynamic(int fd, char *filename, char *cgiargs);
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void error_request(int fd, char *cause, char *errnum,
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char *shortmsg, char *description);
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/* 支持的文件扩展名及其对应的MIME类型 */
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struct {
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char *ext; // 文件扩展名
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char *filetype; // MIME类型
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} extensions[] = {
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{".gif", "image/gif"},
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{".jpg", "image/jpg"},
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{".jpeg", "image/jpeg"},
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{".png", "image/png"},
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{".ico", "image/ico"},
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{".zip", "image/zip"},
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{".gz", "image/gz"},
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{".tar", "image/tar"},
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{".htm", "text/html"},
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{".html", "text/html"},
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{0, 0} // 结束标志
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};
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/* 调试模式宏定义 */
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#ifdef DEBUG
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#define printf2(format, var) printf(format,var)
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#define printf3(format,var1,var2) printf(format,var1,var2)
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#else
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#define printf2(format, var)
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#define printf3(format,var1,var2)
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#endif
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/* 全局变量说明 */
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void sigchld_handler(int sig)
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{
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while (waitpid(-1, 0, WNOHANG) > 0);
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return;
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}
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typedef void (*sighandler_t) (int sig) ;
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void Signal(int sig, sighandler_t handler){
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struct sigaction sa;
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sa.sa_handler = handler;
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sigemptyset(&sa.sa_mask);
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sa.sa_flags = SA_RESTART; // 确保被信号中断的系统调用自动重启
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sigaction(sig, &sa, NULL);
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}
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/* Ctrl+C信号处理函数 */
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void ctrlc_handler(int sig)
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{
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printf("您按下了Ctrl+C终止了Web服务器\n");
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exit(0);
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}
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/* 主函数：监听端口并处理客户端连接 */
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int main(int argc, char **argv)
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{
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int listen_sock, conn_sock, port;
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int hit; // 请求计数器
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socklen_t clientlen;
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struct sockaddr_in clientaddr;
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/* 检查命令行参数 */
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if (argc != 2) {
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fprintf(stderr, "用法: %s <端口号>\n", argv[0]);
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exit(1);
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}
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port = atoi(argv[1]);
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//设置SIGHLD的信号处理函数，用于收割结束的子进程
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Signal(SIGCHLD, sigchld_handler);
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Signal(SIGPIPE, SIG_IGN);
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listen_sock = open_listen_sock(port);
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for (hit=1; ; hit++) { //hit为第几次请求，或第几次http事务
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clientlen = sizeof(clientaddr);
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conn_sock = accept(listen_sock, (SA *)&clientaddr, &clientlen);
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if (fork() == 0) {
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close(listen_sock); /* Child process closes its listening socket */
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process_trans(conn_sock,hit); // 处理HTTP事务
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close(conn_sock); /* Child process closes connection with client */
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exit(0); /* Child process exits */
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}
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close(conn_sock);
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}
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exit(0);
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}
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/* 处理HTTP事务的核心函数 */
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void process_trans(int fd,int hit)
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{
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int static_flag; // 是否为静态资源标志
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struct stat sbuf; // 文件状态信息
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char buf[MAXLINE], method[MAXLINE], uri[MAXLINE], version[MAXLINE];
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char filename[MAXLINE], cgiargs[MAXLINE];
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rio_t rio;
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int rhn=0; // 请求头计数器
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/* 设置Ctrl+C信号处理 */
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if(signal(SIGINT,ctrlc_handler)==SIG_ERR)
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(void)printf("错误: 无法设置SIGINT信号处理\n");
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printf2("第%d次请求开始\n",hit);
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/* 读取请求行和请求头 */
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rio_readinitb(&rio, fd);
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rio_readlineb(&rio, buf, MAXLINE);
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printf3("请求头%d:%s", ++rhn, buf);
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sscanf(buf, "%s %s %s", method, uri, version);
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if (strcasecmp(method, "GET")) { // 仅支持GET方法
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error_request(fd, method, "501", "未实现",
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"本服务器不支持该请求方法");
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return;
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}
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read_requesthdrs(&rio,hit,rhn); // 读取剩余请求头
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static_flag = is_static(uri); // 判断资源类型
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if(static_flag)
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parse_static_uri(uri, filename); // 解析静态资源路径
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else
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parse_dynamic_uri(uri, filename, cgiargs); // 解析动态资源路径和参数
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/* 检查文件是否存在及权限 */
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if (stat(filename, &sbuf) < 0) {
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error_request(fd, filename, "404", "未找到",
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"服务器无法找到该文件");
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return;
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}
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/* 根据资源类型发送响应 */
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if (static_flag) { // 静态资源处理
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if (!(S_ISREG(sbuf.st_mode)) || !(S_IRUSR & sbuf.st_mode)) {
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error_request(fd, filename, "403", "禁止访问",
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"服务器无权读取该文件");
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return;
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}
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feed_static(fd, filename, sbuf.st_size); // 发送静态文件内容
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}
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else { // 动态资源处理
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if (!(S_ISREG(sbuf.st_mode)) || !(S_IXUSR & sbuf.st_mode)) {
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error_request(fd, filename, "403", "禁止访问",
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"服务器无法执行该CGI程序");
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return;
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}
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feed_dynamic(fd, filename, cgiargs); // 执行CGI程序并发送输出
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}
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}
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/* 判断URI是否对应静态资源 */
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int is_static(char *uri)
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{
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return strstr(uri, "cgi-bin") == NULL; // 不含cgi-bin则为静态资源
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}
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/* 构造HTTP错误响应 */
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void error_request(int fd, char *cause, char *errnum,
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char *shortmsg, char *description)
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{
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char buf[MAXLINE], body[MAXBUF];
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/* 构建错误页面内容 */
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sprintf(body, "<html><title>错误请求</title>");
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sprintf(body, "%s<body bgcolor=\"#ffffff\">\r\n", body);
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sprintf(body, "%s<h1>%s %s</h1>\r\n", body, errnum, shortmsg);
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sprintf(body, "%s<p>%s: %s</p>\r\n", body, description, cause);
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sprintf(body, "%s<hr><em>weblet Web服务器</em>\r\n", body);
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/* 发送HTTP响应头 */
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sprintf(buf, "HTTP/1.0 %s %s\r\n", errnum, shortmsg);
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rio_writen(fd, buf, strlen(buf));
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sprintf(buf, "Content-type: text/html\r\n");
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rio_writen(fd, buf, strlen(buf));
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sprintf(buf, "Content-length: %d\r\n\r\n", (int)strlen(body));
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rio_writen(fd, buf, strlen(buf));
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/* 发送错误页面内容 */
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rio_writen(fd, body, strlen(body));
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}
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/* 读取请求头直到空行 */
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void read_requesthdrs(rio_t *rp,int hit, int rhn)
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{
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char buf[MAXLINE];
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rio_readlineb(rp, buf, MAXLINE);
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while(strcmp(buf, "\r\n")) {
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printf3("请求头%d:%s", ++rhn, buf);
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rio_readlineb(rp, buf, MAXLINE);
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}
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printf2("第%d次请求结束\n\n",hit);
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}
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/* 解析静态资源URI到文件路径 */
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void parse_static_uri(char *uri, char *filename)
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{
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strcpy(filename, ".");
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strcat(filename, uri);
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if (uri[strlen(uri)-1] == '/')
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strcat(filename, "index.html"); // 默认返回index.html
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}
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/* 解析动态资源URI到文件路径和参数 */
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void parse_dynamic_uri(char *uri, char *filename, char *cgiargs)
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{
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char *ptr = index(uri, '?');
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if (ptr) {
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strcpy(cgiargs, ptr+1); // 提取参数部分请求头
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*ptr = '\0'; // 截断URI
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} else {
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strcpy(cgiargs, "");
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}
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strcpy(filename, ".");
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strcat(filename, uri);
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}
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/* 发送静态文件内容 */
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void feed_static(int fd, char *filename, int filesize)
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{
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int srcfd;
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char *srcp, filetype[MAXLINE], buf[MAXBUF];
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/* 发送HTTP响应头 */
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get_filetype(filename, filetype);
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sprintf(buf, "HTTP/1.0 200 OK\r\n");
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sprintf(buf, "%sServer: weblet Web Server\r\n", buf);
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sprintf(buf, "%sContent-length: %d\r\n", buf, filesize);
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sprintf(buf, "%sContent-type: %s\r\n\r\n", buf, filetype);
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rio_writen(fd, buf, strlen(buf));
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/* 发送文件内容 */
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srcfd = open(filename, O_RDONLY, 0);
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srcp = mmap(0, filesize, PROT_READ, MAP_PRIVATE, srcfd, 0);
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close(srcfd);
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rio_writen(fd, srcp, filesize);
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munmap(srcp, filesize);
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}
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/* 根据文件扩展名获取MIME类型 */
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void get_filetype(char *filename, char *filetype)
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{
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int i, len;
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strcpy(filetype, "text/html"); // 默认类型
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for (i = 0; extensions[i].ext != 0; i++) {
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len = strlen(extensions[i].ext);
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if (!strcmp(&filename[strlen(filename)-len], extensions[i].ext)) {
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strcpy(filetype, extensions[i].filetype);
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break;
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}
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}
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}
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/* 启动子进程执行CGI程序 */
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void feed_dynamic(int fd, char *filename, char *cgiargs)
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{
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char buf[MAXLINE], *emptylist[] = { NULL };
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int pfd[2];
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/* 构造HTTP响应头 */
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sprintf(buf, "HTTP/1.0 200 OK\r\n");
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rio_writen(fd, buf, strlen(buf));
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sprintf(buf, "Server: weblet Web Server\r\n");
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rio_writen(fd, buf, strlen(buf));
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/* 创建管道并启动子进程 */
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(void)pipe(pfd);
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if (fork() == 0) { // 子进程
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close(pfd[1]); // 关闭写端
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dup2(pfd[0], STDIN_FILENO); // 重定向标准输入
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dup2(fd, STDOUT_FILENO); // 重定向标准输出到客户端
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execve(filename, emptylist, environ); // 执行CGI程序
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}
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close(pfd[0]); // 父进程关闭读端
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(void)write(pfd[1], cgiargs, strlen(cgiargs)+1); // 传递参数
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wait(NULL); // 等待子进程结束
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close(pfd[1]); // 关闭写端
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}
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