diff options
Diffstat (limited to 'netcon')
| -rw-r--r-- | netcon/tiny-web-server.c | 253 |
1 files changed, 253 insertions, 0 deletions
diff --git a/netcon/tiny-web-server.c b/netcon/tiny-web-server.c new file mode 100644 index 00000000..ca9ef0b7 --- /dev/null +++ b/netcon/tiny-web-server.c @@ -0,0 +1,253 @@ +/* + * tiny.c - a minimal HTTP server that serves static and + * dynamic content with the GET method. Neither + * robust, secure, nor modular. Use for instructional + * purposes only. + * Dave O'Hallaron, Carnegie Mellon + * + * usage: tiny <port> + */ + +#include <stdio.h> +#include <unistd.h> +#include <stdlib.h> +#include <string.h> +#include <netdb.h> +#include <fcntl.h> +#include <sys/types.h> +#include <sys/socket.h> +#include <sys/stat.h> +#include <sys/mman.h> +#include <sys/wait.h> +#include <netinet/in.h> +#include <arpa/inet.h> + +#define BUFSIZE 1024 +#define MAXERRS 16 + +extern char **environ; /* the environment */ + +/* + * error - wrapper for perror used for bad syscalls + */ +void error(char *msg) { + perror(msg); + exit(1); +} + +/* + * cerror - returns an error message to the client + */ +void cerror(FILE *stream, char *cause, char *errno, + char *shortmsg, char *longmsg) { + fprintf(stream, "HTTP/1.1 %s %s\n", errno, shortmsg); + fprintf(stream, "Content-type: text/html\n"); + fprintf(stream, "\n"); + fprintf(stream, "<html><title>Tiny Error</title>"); + fprintf(stream, "<body bgcolor=""ffffff"">\n"); + fprintf(stream, "%s: %s\n", errno, shortmsg); + fprintf(stream, "<p>%s: %s\n", longmsg, cause); + fprintf(stream, "<hr><em>The Tiny Web server</em>\n"); +} + +int main(int argc, char **argv) { + + /* variables for connection management */ + int parentfd; /* parent socket */ + int childfd; /* child socket */ + int portno; /* port to listen on */ + int clientlen; /* byte size of client's address */ + int optval; /* flag value for setsockopt */ + struct sockaddr_in serveraddr; /* server's addr */ + struct sockaddr_in clientaddr; /* client addr */ + + /* variables for connection I/O */ + FILE *stream; /* stream version of childfd */ + char buf[BUFSIZE]; /* message buffer */ + char method[BUFSIZE]; /* request method */ + char uri[BUFSIZE]; /* request uri */ + char version[BUFSIZE]; /* request method */ + char filename[BUFSIZE];/* path derived from uri */ + char filetype[BUFSIZE];/* path derived from uri */ + char cgiargs[BUFSIZE]; /* cgi argument list */ + char *p; /* temporary pointer */ + int is_static; /* static request? */ + struct stat sbuf; /* file status */ + int fd; /* static content filedes */ + int pid; /* process id from fork */ + int wait_status; /* status from wait */ + + /* check command line args */ + if (argc != 2) { + fprintf(stderr, "usage: %s <port>\n", argv[0]); + exit(1); + } + portno = atoi(argv[1]); + + /* open socket descriptor */ + parentfd = socket(AF_INET, SOCK_STREAM, 0); + if (parentfd < 0) + error("ERROR opening socket"); + + /* allows us to restart server immediately */ + optval = 1; + setsockopt(parentfd, SOL_SOCKET, SO_REUSEADDR, + (const void *)&optval , sizeof(int)); + + /* bind port to socket */ + bzero((char *) &serveraddr, sizeof(serveraddr)); + serveraddr.sin_family = AF_INET; + serveraddr.sin_addr.s_addr = htonl(INADDR_ANY); + serveraddr.sin_port = htons((unsigned short)portno); + if (bind(parentfd, (struct sockaddr *) &serveraddr, + sizeof(serveraddr)) < 0) + error("ERROR on binding"); + + /* get us ready to accept connection requests */ + if (listen(parentfd, 5) < 0) /* allow 5 requests to queue up */ + error("ERROR on listen"); + + /* + * main loop: wait for a connection request, parse HTTP, + * serve requested content, close connection. + */ + clientlen = sizeof(clientaddr); + while (1) { + + /* wait for a connection request */ + childfd = accept(parentfd, (struct sockaddr *) &clientaddr, &clientlen); + if (childfd < 0) + error("ERROR on accept"); + + /* open the child socket descriptor as a stream */ + if ((stream = fdopen(childfd, "r+")) == NULL) + error("ERROR on fdopen"); + + /* get the HTTP request line */ + fgets(buf, BUFSIZE, stream); + printf("%s", buf); + sscanf(buf, "%s %s %s\n", method, uri, version); + + /* tiny only supports the GET method */ + if (strcasecmp(method, "GET")) { + cerror(stream, method, "501", "Not Implemented", + "Tiny does not implement this method"); + fclose(stream); + close(childfd); + continue; + } + + /* read (and ignore) the HTTP headers */ + fgets(buf, BUFSIZE, stream); + printf("%s", buf); + while(strcmp(buf, "\r\n")) { + fgets(buf, BUFSIZE, stream); + printf("%s", buf); + } + + /* parse the uri [crufty] */ + if (!strstr(uri, "cgi-bin")) { /* static content */ + is_static = 1; + strcpy(cgiargs, ""); + strcpy(filename, "."); + strcat(filename, uri); + if (uri[strlen(uri)-1] == '/') + strcat(filename, "index.html"); + } + else { /* dynamic content */ + is_static = 0; + p = index(uri, '?'); + if (p) { + strcpy(cgiargs, p+1); + *p = '\0'; + } + else { + strcpy(cgiargs, ""); + } + strcpy(filename, "."); + strcat(filename, uri); + } + + /* make sure the file exists */ + if (stat(filename, &sbuf) < 0) { + cerror(stream, filename, "404", "Not found", + "Tiny couldn't find this file"); + fclose(stream); + close(childfd); + continue; + } + + /* serve static content */ + if (is_static) { + if (strstr(filename, ".html")) + strcpy(filetype, "text/html"); + else if (strstr(filename, ".gif")) + strcpy(filetype, "image/gif"); + else if (strstr(filename, ".jpg")) + strcpy(filetype, "image/jpg"); + else + strcpy(filetype, "text/plain"); + + /* print response header */ + fprintf(stream, "HTTP/1.1 200 OK\n"); + fprintf(stream, "Server: Tiny Web Server\n"); + fprintf(stream, "Content-length: %d\n", (int)sbuf.st_size); + fprintf(stream, "Content-type: %s\n", filetype); + fprintf(stream, "\r\n"); + fflush(stream); + + /* Use mmap to return arbitrary-sized response body */ + fd = open(filename, O_RDONLY); + p = mmap(0, sbuf.st_size, PROT_READ, MAP_PRIVATE, fd, 0); + fwrite(p, 1, sbuf.st_size, stream); + munmap(p, sbuf.st_size); + } + + /* serve dynamic content */ + else { + /* make sure file is a regular executable file */ + if (!(S_IFREG & sbuf.st_mode) || !(S_IXUSR & sbuf.st_mode)) { + cerror(stream, filename, "403", "Forbidden", + "You are not allow to access this item"); + fclose(stream); + close(childfd); + continue; + } + + /* a real server would set other CGI environ vars as well*/ + setenv("QUERY_STRING", cgiargs, 1); + + /* print first part of response header */ + sprintf(buf, "HTTP/1.1 200 OK\n"); + write(childfd, buf, strlen(buf)); + sprintf(buf, "Server: Tiny Web Server\n"); + write(childfd, buf, strlen(buf)); + + /* create and run the child CGI process so that all child + output to stdout and stderr goes back to the client via the + childfd socket descriptor */ + pid = fork(); + if (pid < 0) { + perror("ERROR in fork"); + exit(1); + } + else if (pid > 0) { /* parent process */ + wait(&wait_status); + } + else { /* child process*/ + close(0); /* close stdin */ + dup2(childfd, 1); /* map socket to stdout */ + dup2(childfd, 2); /* map socket to stderr */ + if (execve(filename, NULL, environ) < 0) { + perror("ERROR in execve"); + } + } + } + + /* clean up */ + fclose(stream); + close(childfd); + + } +} + |