Adam Ierymenko
10 years ago
2 changed files with 254 additions and 1 deletions
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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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#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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#define BUFSIZE 1024 |
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#define MAXERRS 16 |
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extern char **environ; /* the environment */ |
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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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* 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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int main(int argc, char **argv) { |
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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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/* 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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/* 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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/* 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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/* 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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/* 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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/* 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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* 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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/* 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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/* 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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/* 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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/* 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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/* 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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/* 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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/* 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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/* 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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/* 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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/* 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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/* 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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/* a real server would set other CGI environ vars as well*/ |
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setenv("QUERY_STRING", cgiargs, 1);
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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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/* 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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/* 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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