/* * Original version from Doug Comer's book "Internetworking with TCP/IP" * Revisions * 1. Added tcplib.c to simplify the socket creation. * 2. Removed the checking of Solaris and Windows, just concentrating * on linux. * * Xiannong Meng * 2015-12-11 * * Note: * 1. This version of web server processes only the first pair of * name/value in the "POST" message (e.g., forms), the rest paris * will be ignored. To handle more pairs, one need to re-write * part of the "process_post()" function. */ /* webserver.c */ #define _GNU_SOURCE // we want to use the strcasestr() function #include #include #include #include #include #include #include #include "tcplib.h" #include "image_type.h" // various image types #include "http_response.h" // HTTP response codes and strings #define NONEXST -1 // result of file access attempt #define NONREAD 0 #define READBLE 1 #define BUFFSIZE 256 #define FILESIZE 65536*16 #define SERVER_NAME "polaris.bucknell.edu" #define HOME_PAGE "

Welcome to Simple\ Web Server

Why not visit:

Or try a \ normal HTML page

Or try a sample photo

Or try something doesn't exist (Error 404).

Or try a page that has been moved. (Error 301)

Or try the time\ page.

or try to send infor to the server.\n" #define TIME_PAGE "

The current date is\ : %s

\n" int recvln(int, char *, int); void send_head(int, int, int, char*); int read_file(char*, char*); int get_file_size(char*); void process_post(int, char*); void process_get(char*, int); void process_head(char*, int); int is_valid_http_req(char*, char*); extern int determine_image_type(char * path); /*----------------------------------------------------------------------- * * Program: webserver * Purpose: serve hard-coded webpages to web clients * Usage: webserver * *----------------------------------------------------------------------- */ int main(int argc, char *argv[]) { int conn; // connection point int sock; // socket number int port; // port number int n; // size char buff[BUFFSIZE], cmd[16], path[64], vers[16]; char header[8*BUFFSIZE]; // http header if (argc != 2) { (void) fprintf(stderr, "usage: %s \n", argv[0]); (void) fprintf(stderr, "for example : %s 8688\n", argv[0]); exit(1); } port = atoi(argv[1]); sock = socketServer(port); while(1) { /* wait for contact from a client on specified appnum */ conn = acceptConn(sock); if (conn < 0) exit(1); /* read and parse the request line */ n = recvln(conn, buff, BUFFSIZE); buff[n] = 0; fprintf(stderr,"cmd from browser: %s\n", buff); sscanf(buff, "%s %s %s", cmd, path, vers); header[0] = 0; // initialize header, to be used in processing "post" /* * Read until we get \r\n alone, saving the header. * We read one line at a time so we can catch "\r\n" * by itself. */ while((n = recvln(conn, buff, BUFFSIZE)) > 0) { buff[n] = 0; strncat(header, buff, n); fprintf(stderr,"cmd from browser: %s\n", buff); if (n == 2 && buff[0] == '\r' && buff[1] == '\n') break; } /* check for unexpected end of file */ if (n < 1) { (void) send_eof(conn); continue; } /* check for a request that we cannot understand */ if (is_valid_http_req(cmd, vers) == 0 ) { // invalid request send_head(conn, 400, strlen(ERROR_400), "text/html"); (void) send(conn, ERROR_400, strlen(ERROR_400), 0); (void) send_eof(conn); continue; } /* process posted form */ if (strcasecmp(cmd, "POST") == 0) { process_post(conn, header); } else if (strcasecmp(cmd, "GET") == 0) { /* process GET */ process_get(path, conn); } else if (strcasecmp(cmd, "HEAD") == 0) { /* process HEAD */ process_head(path, conn); } } /* end of while (1) */ } /*------------------------------------------------------- * Determine if an HTTP request from the client is valid. * * parameters: * cmd: HTTP command such as GET or POSt * vers: version of http, 1.0 or 1.1 * * return: * 0 if the request is invliad, 1 otherwise *------------------------------------------------------- */ int is_valid_http_req(char * cmd, char * vers) { if ((strcasecmp(cmd, "GET") && strcasecmp(cmd, "POST") && strcasecmp(cmd, "HEAD")) || (strcasecmp(vers, "HTTP/1.0") && strcasecmp(vers, "HTTP/1.1"))) { return 0; // invalid } else { return 1; // valid } } /*------------------------------------------------------- * Extract "content-length" from the header * * parameters: * header: HTTP header which should include "content-length" * * return: * the integer form of the "content-length" *------------------------------------------------------- */ int get_content_length(char * header) { char *lengthPtr; // search where the length value is lengthPtr = strcasestr(header, "content-length"); if (lengthPtr == NULL) return 0; /* now extract the integer value */ // first skip all non-digit chars while (!isdigit(*lengthPtr)) lengthPtr ++; // keep the begining of the digit char *digitsPtr = lengthPtr; // now skip until the end of the digits while (isdigit(*lengthPtr)) lengthPtr ++; char digits[32]; // assume the integer is less than 32 digits // copy the number, (len + 1) to terminate the string strncpy(digits, digitsPtr, (lengthPtr - digitsPtr) + 1); // terminate the string digits[(lengthPtr - digitsPtr)]; return atoi(digits); } /*--------------------------------------------------- * This is a simplified vesion of the function. It * assumes that there is only one pair of name/value! * The function processes the post information, returning * proper response in HTML form. * * parameters: * conn: socket connection * header: HTTP header from the client (e.g., browser) *--------------------------------------------------- */ void process_post(int conn, char * header) { int n; char buff[4*BUFFSIZE]; // assume the form is no longer than this char name[BUFFSIZE], value[BUFFSIZE]; // for the name/value pair char retContent[4*BUFFSIZE]; // returning html page // extract the integer representing the content length int contentLength = get_content_length(header); if (contentLength == 0) { send_head(conn, 404, strlen(ERROR_404), "text/html"); (void) send(conn, ERROR_404, strlen(ERROR_404),0); return; } // read the form from browser n = recv(conn, buff, contentLength, 0); // buff should be in the form of "n1=v1&n2=v2&n3=v3" buff[n] = 0; // extract the first name/value pair, look for '=' char * assign = strstr(buff, "="); n = strlen(buff) - strlen(assign); strncpy(name, buff, n); name[n] = 0; // then look for '&' char * amp = strstr(buff, "&"); n = strlen(assign) - strlen(amp); strncpy(value, (assign+1), n-1); value[n] = 0; // build HTML code for display strcpy(retContent, "

"); strcat(retContent, name); strcat(retContent, ": : "); strcat(retContent, value); strcat(retContent, ":
\n"); strcat(retContent, "

\n"); // return the header first n = strlen(retContent); send_head(conn, 200, n, "text/html"); // return the contents (void) send(conn, retContent, n, 0); } /*--------------------------------------------------- * Process the HTTP "HEAD" command, returns meta- * information about the resource requested * * parameters: * path: file path for the requested document * conn: socket for the connection * *--------------------------------------------------- */ void process_head(char * path, int conn) { int n; /* read/write size */ int fstatus; // file status char * fname = path; int ftype; // file type /* * This function works, but is incomplete. Rewrite the following * segment to make the function work as intended. */ char * response = "

This function is yet to be complete.\

"; n = strlen(response); send_head(conn, 200, n, "text/html"); send(conn, response, n, 0); (void) send_eof(conn); } /*--------------------------------------------------- * Process the HTTP "GET" command, returns some hard- * coded HTML files. * * parameters: * path: file path for the requested document * conn: socket for the connection * *--------------------------------------------------- */ void process_get(char * path, int conn) { char data[FILESIZE]; /* file content, such as JLH.jpg photo */ char buff[BUFFSIZE]; int n; /* read/write size */ char *timestr; struct timeval tv; int fstatus; // file status /* send the requested web page or any error message */ if (strcmp(path, "/") == 0) { send_head(conn, 200, strlen(HOME_PAGE), "text/html"); (void) send(conn, HOME_PAGE, strlen(HOME_PAGE), 0); } else if (strcmp(path, "/default.html") == 0) { n = read_file("default.html", data); send_head(conn, 200, n, "text/html"); (void) send(conn, data, n, 0); } else if (strcmp(path, "/time") == 0) { gettimeofday(&tv, NULL); timestr = ctime(&tv.tv_sec); (void) sprintf(buff, TIME_PAGE, timestr); send_head(conn, 200, strlen(buff), "text/html"); (void) send(conn, buff, strlen(buff), 0); } else if (strcmp(path, "/moved.html") == 0) { send_head(conn, 301, strlen(ERROR_301), "text/html"); (void) send(conn, ERROR_301, strlen(ERROR_301), 0); } else if (strcmp(path, "/JLH.jpg") == 0 || strcmp(path, "/form.html") == 0) { /* request one of the two files */ char * fname = path; fname = fname ++; // moveover the leading '/' fstatus = check_file_status(fname); if (fstatus == READBLE) { // ok n = read_file(fname, data); if (strcmp(path, "/JLH.jpg") == 0) // the image file send_head(conn, 200, n, "image/jpeg"); else // the form.html, html file send_head(conn, 200, n, "text/html"); (void) send(conn, data, n, 0); } else if (fstatus == NONEXST) { // not found send_head(conn, 404, strlen(ERROR_404), "text/html"); (void) send(conn, ERROR_404, strlen(ERROR_404), 0); } else if (fstatus == NONREAD) { // forbidden send_head(conn, 403, strlen(ERROR_403), "text/html"); (void) send(conn, ERROR_403, strlen(ERROR_403), 0); } else { send_head(conn, 500, strlen(ERROR_500), "text/html"); (void) send(conn, ERROR_500, strlen(ERROR_500), 0); } } else { /* not found */ send_head(conn, 404, strlen(ERROR_404), "text/html"); (void) send(conn, ERROR_404, strlen(ERROR_404), 0); } (void) send_eof(conn); } /*----------------------------------------------------------------------- * send_head - send an HTTP 1.0 header with given status and content-len * * parameters: * conn: socket connection * stat: HTTP status code * len: content length * type: content type *----------------------------------------------------------------------- */ void send_head(int conn, int stat, int len, char * type) { char *statstr, buff[BUFFSIZE]; char *timestr; struct timeval tv; /* convert the status code to a string */ switch(stat) { case 200: statstr = "OK"; break; case 301: statstr = "Moved"; break; case 400: statstr = "Bad Request"; break; case 403: statstr = "No Permission"; break; case 404: statstr = "Not Found"; break; case 500: statstr = "Internal Error"; break; default: statstr = "Unknown"; break; } /* * send an HTTP/1.0 response with Server, Content-Length, * and Content-Type headers. */ (void) sprintf(buff, "HTTP/1.0 %d %s\r\n", stat, statstr); (void) send(conn, buff, strlen(buff), 0); /** try out cookie! **/ gettimeofday(&tv, NULL); // retrieve current time tv.tv_sec += 120; // so the cookie expires in time timestr = ctime(&tv.tv_sec); (void) sprintf(buff, "Set-Cookie: new=value; version=1; "); // (void) sprintf(buff, "Set-Cookie: name3=value3; "); (void) send(conn, buff, strlen(buff), 0); // (void) sprintf(buff, "expires=Wed, 01-December-2004 16:00:00 GMT; "); (void) sprintf(buff, "expires=%s; ", timestr); (void) send(conn, buff, strlen(buff), 0); (void) sprintf(buff, "path=/time; domain=.eg.bucknell.edu\n"); (void) send(conn, buff, strlen(buff), 0); /** (void) sprintf(buff, "Server: %s", SERVER_NAME); (void) send(conn, buff, strlen(buff), 0); **/ (void) sprintf(buff, "Content-Length: %d\n", len); (void) send(conn, buff, strlen(buff), 0); (void) sprintf(buff, "Content-Type: %s\n", type); (void) send(conn, buff, strlen(buff), 0); (void) sprintf(buff, "\n"); (void) send(conn, buff, strlen(buff), 0); } /*----------------------------------------------------------------------- * read_file: read content of given file name, pass back the buff *----------------------------------------------------------------------- */ int read_file(char * fname, char buff[FILESIZE]) { FILE * f = fopen(fname, "r"); int size_read = fread(buff, 1, FILESIZE-1, f); if (size_read > 0) { buff[size_read] = 0; } fclose(f); return size_read; } /*----------------------------------------------------------------------- * Check the file status to see if the client has the permission to access * * parameters: * fname: the name of the file to access * * return: * -2: unknown * -1: doesn't exist * 0: readable * 1: not readable *----------------------------------------------------------------------- */ int check_file_status(char * fname) { // container for complete set of file permission bits (binary) unsigned int mode; // container for the three bits of other permission unsigned int omode; // structure to contain the result of the fstat call (info on this file) struct stat file_info; // return status int file_status = -2; // status unknown // try to access file file_status = stat(fname, &file_info); if (file_status != 0) { // stat() call failed file_status = -1; } else { // mode comes from the lower 9 bits in file_info.st_mode mode = file_info.st_mode & 0x1FF; // omode comes from the low 3 bits in mode omode = mode & S_IRWXO; // 0o00007 if (omode < 4) { // 4 == 100 in rwx file_status = 0; // unreadable } else { file_status = 1; // readable } } // end of file exists return file_status; } /* *--------------------------------------------------- * Return the size of a given file. *--------------------------------------------------- */ int get_file_size(char * fname) { // default file size int file_size = 0; int file_status = 0; // structure to contain the result of the fstat call (info on this file) struct stat file_info; // try to access file file_status = stat(fname, &file_info); if (file_status != 0) { // stat() call failed file_size = 0; } else { // extract file size file_size = file_info.st_size; } return file_size; }