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+/*
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+ * tiny.c - a minimal HTTP server that serves static and
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+ * dynamic content with the GET method. Neither
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+ * robust, secure, nor modular. Use for instructional
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+ * purposes only.
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+ * Dave O'Hallaron, Carnegie Mellon
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+ *
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+ * usage: tiny <port>
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+ */
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+
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+#include <stdio.h>
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+#include <unistd.h>
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+#include <stdlib.h>
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+#include <string.h>
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+#include <netdb.h>
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+#include <fcntl.h>
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+#include <sys/types.h>
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+#include <sys/socket.h>
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+#include <sys/stat.h>
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+#include <sys/mman.h>
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+#include <sys/wait.h>
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+#include <netinet/in.h>
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+#include <arpa/inet.h>
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+
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+#define BUFSIZE 1024
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+#define MAXERRS 16
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+
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+extern char **environ; /* the environment */
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+
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+/*
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+ * error - wrapper for perror used for bad syscalls
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+ */
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+void error(char *msg) {
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+ perror(msg);
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+ exit(1);
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+}
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+
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+/*
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+ * cerror - returns an error message to the client
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+ */
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+void cerror(FILE *stream, char *cause, char *errno,
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+ char *shortmsg, char *longmsg) {
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+ fprintf(stream, "HTTP/1.1 %s %s\n", errno, shortmsg);
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+ fprintf(stream, "Content-type: text/html\n");
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+ fprintf(stream, "\n");
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+ fprintf(stream, "<html><title>Tiny Error</title>");
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+ fprintf(stream, "<body bgcolor=""ffffff"">\n");
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+ fprintf(stream, "%s: %s\n", errno, shortmsg);
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+ fprintf(stream, "<p>%s: %s\n", longmsg, cause);
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+ fprintf(stream, "<hr><em>The Tiny Web server</em>\n");
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+}
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+
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+int main(int argc, char **argv) {
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+
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+ /* variables for connection management */
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+ int parentfd; /* parent socket */
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+ int childfd; /* child socket */
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+ int portno; /* port to listen on */
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+ int clientlen; /* byte size of client's address */
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+ int optval; /* flag value for setsockopt */
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+ struct sockaddr_in serveraddr; /* server's addr */
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+ struct sockaddr_in clientaddr; /* client addr */
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+
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+ /* variables for connection I/O */
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+ FILE *stream; /* stream version of childfd */
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+ char buf[BUFSIZE]; /* message buffer */
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+ char method[BUFSIZE]; /* request method */
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+ char uri[BUFSIZE]; /* request uri */
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+ char version[BUFSIZE]; /* request method */
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+ char filename[BUFSIZE];/* path derived from uri */
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+ char filetype[BUFSIZE];/* path derived from uri */
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+ char cgiargs[BUFSIZE]; /* cgi argument list */
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+ char *p; /* temporary pointer */
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+ int is_static; /* static request? */
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+ struct stat sbuf; /* file status */
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+ int fd; /* static content filedes */
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+ int pid; /* process id from fork */
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+ int wait_status; /* status from wait */
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+
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+ /* check command line args */
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+ if (argc != 2) {
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+ fprintf(stderr, "usage: %s <port>\n", argv[0]);
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+ exit(1);
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+ }
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+ portno = atoi(argv[1]);
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+
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+ /* open socket descriptor */
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+ parentfd = socket(AF_INET, SOCK_STREAM, 0);
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+ if (parentfd < 0)
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+ error("ERROR opening socket");
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+
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+ /* allows us to restart server immediately */
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+ optval = 1;
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+ setsockopt(parentfd, SOL_SOCKET, SO_REUSEADDR,
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+ (const void *)&optval , sizeof(int));
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+
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+ /* bind port to socket */
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+ bzero((char *) &serveraddr, sizeof(serveraddr));
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+ serveraddr.sin_family = AF_INET;
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+ serveraddr.sin_addr.s_addr = htonl(INADDR_ANY);
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+ serveraddr.sin_port = htons((unsigned short)portno);
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+ if (bind(parentfd, (struct sockaddr *) &serveraddr,
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+ sizeof(serveraddr)) < 0)
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+ error("ERROR on binding");
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+
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+ /* get us ready to accept connection requests */
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+ if (listen(parentfd, 5) < 0) /* allow 5 requests to queue up */
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+ error("ERROR on listen");
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+
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+ /*
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+ * main loop: wait for a connection request, parse HTTP,
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+ * serve requested content, close connection.
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+ */
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+ clientlen = sizeof(clientaddr);
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+ while (1) {
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+
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+ /* wait for a connection request */
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+ childfd = accept(parentfd, (struct sockaddr *) &clientaddr, &clientlen);
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+ if (childfd < 0)
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+ error("ERROR on accept");
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+
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+ /* open the child socket descriptor as a stream */
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+ if ((stream = fdopen(childfd, "r+")) == NULL)
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+ error("ERROR on fdopen");
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+
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+ /* get the HTTP request line */
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+ fgets(buf, BUFSIZE, stream);
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+ printf("%s", buf);
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+ sscanf(buf, "%s %s %s\n", method, uri, version);
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+
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+ /* tiny only supports the GET method */
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+ if (strcasecmp(method, "GET")) {
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+ cerror(stream, method, "501", "Not Implemented",
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+ "Tiny does not implement this method");
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+ fclose(stream);
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+ close(childfd);
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+ continue;
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+ }
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+
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+ /* read (and ignore) the HTTP headers */
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+ fgets(buf, BUFSIZE, stream);
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+ printf("%s", buf);
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+ while(strcmp(buf, "\r\n")) {
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+ fgets(buf, BUFSIZE, stream);
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+ printf("%s", buf);
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+ }
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+
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+ /* parse the uri [crufty] */
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+ if (!strstr(uri, "cgi-bin")) { /* static content */
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+ is_static = 1;
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+ strcpy(cgiargs, "");
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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");
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+ }
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+ else { /* dynamic content */
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+ is_static = 0;
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+ p = index(uri, '?');
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+ if (p) {
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+ strcpy(cgiargs, p+1);
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+ *p = '\0';
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+ }
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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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+
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+ /* make sure the file exists */
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+ if (stat(filename, &sbuf) < 0) {
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+ cerror(stream, filename, "404", "Not found",
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+ "Tiny couldn't find this file");
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+ fclose(stream);
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+ close(childfd);
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+ continue;
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+ }
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+
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+ /* serve static content */
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+ if (is_static) {
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+ if (strstr(filename, ".html"))
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+ strcpy(filetype, "text/html");
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+ else if (strstr(filename, ".gif"))
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+ strcpy(filetype, "image/gif");
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+ else if (strstr(filename, ".jpg"))
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+ strcpy(filetype, "image/jpg");
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+ else
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+ strcpy(filetype, "text/plain");
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+
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+ /* print response header */
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+ fprintf(stream, "HTTP/1.1 200 OK\n");
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+ fprintf(stream, "Server: Tiny Web Server\n");
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+ fprintf(stream, "Content-length: %d\n", (int)sbuf.st_size);
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+ fprintf(stream, "Content-type: %s\n", filetype);
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+ fprintf(stream, "\r\n");
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+ fflush(stream);
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+
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+ /* Use mmap to return arbitrary-sized response body */
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+ fd = open(filename, O_RDONLY);
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+ p = mmap(0, sbuf.st_size, PROT_READ, MAP_PRIVATE, fd, 0);
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+ fwrite(p, 1, sbuf.st_size, stream);
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+ munmap(p, sbuf.st_size);
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+ }
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+
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+ /* serve dynamic content */
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+ else {
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+ /* make sure file is a regular executable file */
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+ if (!(S_IFREG & sbuf.st_mode) || !(S_IXUSR & sbuf.st_mode)) {
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+ cerror(stream, filename, "403", "Forbidden",
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+ "You are not allow to access this item");
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+ fclose(stream);
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+ close(childfd);
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+ continue;
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+ }
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+
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+ /* a real server would set other CGI environ vars as well*/
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+ setenv("QUERY_STRING", cgiargs, 1);
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+
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+ /* print first part of response header */
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+ sprintf(buf, "HTTP/1.1 200 OK\n");
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+ write(childfd, buf, strlen(buf));
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+ sprintf(buf, "Server: Tiny Web Server\n");
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+ write(childfd, buf, strlen(buf));
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+
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+ /* create and run the child CGI process so that all child
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+ output to stdout and stderr goes back to the client via the
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+ childfd socket descriptor */
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+ pid = fork();
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+ if (pid < 0) {
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+ perror("ERROR in fork");
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+ exit(1);
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+ }
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+ else if (pid > 0) { /* parent process */
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+ wait(&wait_status);
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+ }
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+ else { /* child process*/
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+ close(0); /* close stdin */
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+ dup2(childfd, 1); /* map socket to stdout */
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+ dup2(childfd, 2); /* map socket to stderr */
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+ if (execve(filename, NULL, environ) < 0) {
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+ perror("ERROR in execve");
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+ }
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+ }
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+ }
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+
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+ /* clean up */
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+ fclose(stream);
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+ close(childfd);
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+
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+ }
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+}
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+
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Adam Ierymenko