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handler.c
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handler.c
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/* handler.c: HTTP Request Handlers */
#include "spidey.h"
#include <errno.h>
#include <limits.h>
#include <string.h>
#include <dirent.h>
#include <sys/stat.h>
#include <unistd.h>
#include <libgen.h> // used for basename in browse_request
/* Internal Declarations */
HTTPStatus handle_browse_request(Request *request);
HTTPStatus handle_file_request(Request *request);
HTTPStatus handle_cgi_request(Request *request);
HTTPStatus handle_error(Request *request, HTTPStatus status);
/**
* Handle HTTP Request.
*
* @param r HTTP Request structure
* @return Status of the HTTP request.
*
* This parses a request, determines the request path, determines the request
* type, and then dispatches to the appropriate handler type.
*
* On error, handle_error should be used with an appropriate HTTP status code.
**/
HTTPStatus handle_request(Request *r) {
HTTPStatus result;
/* Parse request */
if(parse_request(r) < 0){
log("Could not parse request.");
return handle_error(r, HTTP_STATUS_BAD_REQUEST);
}
/* Determine request path */
r->path = determine_request_path(r->uri);
if(r->path == NULL){
log("Could not determine request path.");
return handle_error(r, HTTP_STATUS_NOT_FOUND);
}
debug("HTTP REQUEST PATH: %s", r->path);
/* Dispatch to appropriate request handler type based on file type */
struct stat fileStat;
lstat(r->path, &fileStat);
if (S_ISDIR(fileStat.st_mode)){
result = handle_browse_request(r);
}
else if (S_ISREG(fileStat.st_mode)){
if (access(r->path, X_OK) == 0){
result = handle_cgi_request(r);
}
else if (access(r->path, R_OK) == 0){
result = handle_file_request(r); }
}
else {
result = HTTP_STATUS_BAD_REQUEST;
}
if(result != HTTP_STATUS_OK){
result = handle_error(r, result);
}
log("HTTP REQUEST STATUS: %s", http_status_string(result));
return result;
}
/**
* Handle browse request.
*
* @param r HTTP Request structure.
* @return Status of the HTTP browse request.
*
* This lists the contents of a directory in HTML.
*
* If the path cannot be opened or scanned as a directory, then handle error
* with HTTP_STATUS_NOT_FOUND.
**/
HTTPStatus handle_browse_request(Request *r) {
struct dirent **entries;
int n;
/* Open a directory for reading or scanning */
n = scandir(r->path, &entries, NULL, alphasort);
if(n == -1){
log("Unable to scandir on directory.");
return HTTP_STATUS_NOT_FOUND;
}
/* Write HTTP Header with OK Status and text/html Content-Type */
fprintf(r->file, "HTTP/1.0 200 OK\r\nContent-Type: text/html\r\n\r\n");
/* For each entry in directory, emit HTML list item */
fprintf(r->file, "<ul>");
for(int i = 0; i < n; i++){
if(strcmp(entries[i]->d_name,".") == 0){
free(entries[i]);
continue;
}
if(strcmp(r->uri,"/")==0){
fprintf(r->file,"<li><a href=\"/%s\">%s</a></li>\r\n", entries[i]->d_name, entries[i]->d_name);
}
else{
fprintf(r->file, "<li<a href=\"/%s/%s\">%s</a></li>\r\n",basename(r->path),entries[i]->d_name,entries[i]->d_name);
}
free(entries[i]);
}
fprintf(r->file, "<ul>");
/* Flush socket, return OK */
fflush(r->file);
free(entries);
return HTTP_STATUS_OK;
}
/**
* Handle file request.
*
* @param r HTTP Request structure.
* @return Status of the HTTP file request.
*
* This opens and streams the contents of the specified file to the socket.
*
* If the path cannot be opened for reading, then handle error with
* HTTP_STATUS_NOT_FOUND.
**/
HTTPStatus handle_file_request(Request *r) {
FILE *fs;
char buffer[BUFSIZ];
char *mimetype = NULL;
size_t nread;
/* Open file for reading */
if((fs = fopen(r->path, "r")) == NULL){
log("Could not open file for reading.");
goto fail;
}
/* Determine mimetype */
mimetype = determine_mimetype(r->path);
/* Write HTTP Headers with OK status and determined Content-Type */
if(fprintf(r->file, "HTTP/1.0 200 OK\r\nContent-Type: %s\r\n\r\n", mimetype) < 0){
log("Cannot print to socket.");
goto fail;
}
/* Read from file and write to socket in chunks */
while((nread = fread(buffer, 1, BUFSIZ, fs)) > 0){ // 1 element of size BUFSIZ
if(fwrite(buffer, 1, nread, r->file) != nread){ // write to file, 1 element of size nread
log("Could not write to file");
goto fail;
}
}
/* Close file, flush socket, deallocate mimetype, return OK */
fclose(fs);
fflush(r->file);
free(mimetype);
return HTTP_STATUS_OK;
fail:
/* Close file, free mimetype, return INTERNAL_SERVER_ERROR */
fclose(fs);
free(mimetype);
return HTTP_STATUS_INTERNAL_SERVER_ERROR;
}
/**
* Handle CGI request
*
* @param r HTTP Request structure.
* @return Status of the HTTP file request.
*
* This popens and streams the results of the specified executables to the
* socket.
*
* If the path cannot be popened, then handle error with
* HTTP_STATUS_INTERNAL_SERVER_ERROR.
**/
HTTPStatus handle_cgi_request(Request *r) {
FILE *pfs;
char buffer[BUFSIZ];
if(r->query != NULL){
setenv("QUERY_STRING",r->query,1);
}
else{
setenv("QUERY_STRING","",1);
}
setenv("DOCUMENT_ROOT",RootPath,1);
setenv("REQUEST_URI",r->uri,1);
setenv("REQUEST_METHOD",r->method,1);
setenv("REMOTE_ADDR",r->host,1);
setenv("REMOTE_PORT",r->port,1);
setenv("SCRIPT_FILENAME",r->path,1);
setenv("SERVER_PORT",r->port,1);
/* Export CGI environment variables from request structure:
* http://en.wikipedia.org/wiki/Common_Gateway_Interface */
/* Export CGI environment variables from request headers */
Header* curr = r->headers;
while(curr)
{
if(streq(curr->name,"Host"))
{
setenv("HTTP_HOST",curr->value,1);
}
else if(streq(curr->name,"User-Agent"))
{
setenv("HTTP_USER_AGENT",curr->value,1);
}
else if(streq(curr->name,"Accept"))
{
setenv("HTTP_ACCEPT",curr->value,1);
}
else if(streq(curr->name,"Accept-Language"))
{
setenv("HTTP_ACCEPT_LANGUAGE",curr->value,1);
}
else if(streq(curr->name,"Accept-Encoding"))
{
setenv("HTTP_ACCEPT_ENCODING",curr->value,1);
}
else if(streq(curr->name,"Connection"))
{
setenv("HTTP_CONNECTION",curr->value,1);
}
curr=curr->next;
}
/* POpen CGI Script */
if((pfs=popen(r->path,"r"))==NULL)
{
log("unable to popen");
return HTTP_STATUS_INTERNAL_SERVER_ERROR;
}
/* Copy data from popen to socket */
while(fgets(buffer,BUFSIZ,pfs) !=NULL)
{
if(fputs(buffer,r->file) < 0){
log("Fail to fputs.");
return HTTP_STATUS_INTERNAL_SERVER_ERROR;
}
}
/* Close popen, flush socket, return OK */
pclose(pfs);
fflush(r->file);
return HTTP_STATUS_OK;
}
/**
* Handle displaying error page
*
* @param r HTTP Request structure.
* @return Status of the HTTP error request.
*
* This writes an HTTP status error code and then generates an HTML message to
* notify the user of the error.
**/
HTTPStatus handle_error(Request *r, HTTPStatus status) {
const char *status_string = http_status_string(status);
/* Write HTTP Header */
fprintf(r->file, "HTTP/1.0 %s\r\nContent-Type: text/html\r\n\r\n",status_string);
/* Write HTML Description of Error*/
fprintf(r->file,"<h1>");
fprintf(r->file,"Mr. Bui, I don't feel so good...");
fprintf(r->file,"</h1>");
fprintf(r->file,"<h2>");
fprintf(r->file,"Something went wrong:");
fprintf(r->file,"</h2>");
fprintf(r->file,"<p>");
fprintf(r->file,"%s\n",status_string);
fprintf(r->file,"</p>");
/* Return specified status */
return status;
}
/* vim: set expandtab sts=4 sw=4 ts=8 ft=c: */