/*
This file is part of libmicrohttpd
Copyright (C) 2011 Christian Grothoff (and other contributing authors)
This library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 2.1 of the License, or (at your option) any later version.
This library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public
License along with this library; if not, write to the Free Software
Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*/
/**
* @file post_example.c
* @brief example for processing POST requests using libmicrohttpd
* @author Christian Grothoff
*/
#include <stdlib.h>
#include <string.h>
#include <stdio.h>
#include <errno.h>
#include <time.h>
#include <microhttpd.h>
/**
* Invalid method page.
*/
#define METHOD_ERROR "<html><head><title>Illegal request</title></head><body>Go away.</body></html>"
/**
* Invalid URL page.
*/
#define NOT_FOUND_ERROR "<html><head><title>Not found</title></head><body>Go away.</body></html>"
/**
* Front page. (/)
*/
#define MAIN_PAGE "<html><head><title>Welcome</title></head><body><form action=\"/2\" method=\"post\">What is your name? <input type=\"text\" name=\"v1\" value=\"%s\" /><input type=\"submit\" value=\"Next\" /></body></html>"
/**
* Second page. (/2)
*/
#define SECOND_PAGE "<html><head><title>Tell me more</title></head><body><a href=\"/\">previous</a> <form action=\"/S\" method=\"post\">%s, what is your job? <input type=\"text\" name=\"v2\" value=\"%s\" /><input type=\"submit\" value=\"Next\" /></body></html>"
/**
* Second page (/S)
*/
#define SUBMIT_PAGE "<html><head><title>Ready to submit?</title></head><body><form action=\"/F\" method=\"post\"><a href=\"/2\">previous </a> <input type=\"hidden\" name=\"DONE\" value=\"yes\" /><input type=\"submit\" value=\"Submit\" /></body></html>"
/**
* Last page.
*/
#define LAST_PAGE "<html><head><title>Thank you</title></head><body>Thank you.</body></html>"
/**
* Name of our cookie.
*/
#define COOKIE_NAME "session"
/**
* State we keep for each user/session/browser.
*/
struct Session
{
/**
* We keep all sessions in a linked list.
*/
struct Session *next;
/**
* Unique ID for this session.
*/
char sid[33];
/**
* Reference counter giving the number of connections
* currently using this session.
*/
unsigned int rc;
/**
* Time when this session was last active.
*/
time_t start;
/**
* String submitted via form.
*/
char value_1[64];
/**
* Another value submitted via form.
*/
char value_2[64];
};
/**
* Data kept per request.
*/
struct Request
{
/**
* Associated session.
*/
struct Session *session;
/**
* Post processor handling form data (IF this is
* a POST request).
*/
struct MHD_PostProcessor *pp;
/**
* URL to serve in response to this POST (if this request
* was a 'POST')
*/
const char *post_url;
};
/**
* Linked list of all active sessions. Yes, O(n) but a
* hash table would be overkill for a simple example...
*/
static struct Session *sessions;
/**
* Return the session handle for this connection, or
* create one if this is a new user.
*/
static struct Session *
get_session (struct MHD_Connection *connection)
{
struct Session *ret;
const char *cookie;
cookie = MHD_lookup_connection_value (connection,
MHD_COOKIE_KIND,
COOKIE_NAME);
if (cookie != NULL)
{
/* find existing session */
ret = sessions;
while (NULL != ret)
{
if (0 == strcmp (cookie, ret->sid))
break;
ret = ret->next;
}
if (NULL != ret)
{
ret->rc++;
return ret;
}
}
/* create fresh session */
ret = calloc (1, sizeof (struct Session));
if (NULL == ret)
{
fprintf (stderr, "calloc error: %s\n", strerror (errno));
return NULL;
}
/* not a super-secure way to generate a random session ID,
but should do for a simple example... */
snprintf (ret->sid,
sizeof (ret->sid),
"%X%X%X%X",
(unsigned int) rand (),
(unsigned int) rand (),
(unsigned int) rand (),
(unsigned int) rand ());
ret->rc++;
ret->start = time (NULL);
ret->next = sessions;
sessions = ret;
return ret;
}
/**
* Type of handler that generates a reply.
*
* @param cls content for the page (handler-specific)
* @param mime mime type to use
* @param session session information
* @param connection connection to process
* @param MHD_YES on success, MHD_NO on failure
*/
typedef int (*PageHandler)(const void *cls,
const char *mime,
struct Session *session,
struct MHD_Connection *connection);
/**
* Entry we generate for each page served.
*/
struct Page
{
/**
* Acceptable URL for this page.
*/
const char *url;
/**
* Mime type to set for the page.
*/
const char *mime;
/**
* Handler to call to generate response.
*/
PageHandler handler;
/**
* Extra argument to handler.
*/
const void *handler_cls;
};
/**
* Add header to response to set a session cookie.
*
* @param session session to use
* @param response response to modify
*/
static void
add_session_cookie (struct Session *session,
struct MHD_Response *response)
{
char cstr[256];
snprintf (cstr,
sizeof (cstr),
"%s=%s",
COOKIE_NAME,
session->sid);
if (MHD_NO ==
MHD_add_response_header (response,
MHD_HTTP_HEADER_SET_COOKIE,
cstr))
{
fprintf (stderr,
"Failed to set session cookie header!\n");
}
}
/**
* Handler that returns a simple static HTTP page that
* is passed in via 'cls'.
*
* @param cls a 'const char *' with the HTML webpage to return
* @param mime mime type to use
* @param session session handle
* @param connection connection to use
*/
static int
serve_simple_form (const void *cls,
const char *mime,
struct Session *session,
struct MHD_Connection *connection)
{
int ret;
const char *form = cls;
struct MHD_Response *response;
/* return static form */
response = MHD_create_response_from_buffer (strlen (form),
(void *) form,
MHD_RESPMEM_PERSISTENT);
if (NULL == response)
return MHD_NO;
add_session_cookie (session, response);
MHD_add_response_header (response,
MHD_HTTP_HEADER_CONTENT_ENCODING,
mime);
ret = MHD_queue_response (connection,
MHD_HTTP_OK,
response);
MHD_destroy_response (response);
return ret;
}
/**
* Handler that adds the 'v1' value to the given HTML code.
*
* @param cls unused
* @param mime mime type to use
* @param session session handle
* @param connection connection to use
*/
static int
fill_v1_form (const void *cls,
const char *mime,
struct Session *session,
struct MHD_Connection *connection)
{
int ret;
size_t slen;
char *reply;
struct MHD_Response *response;
(void)cls; /* Unused. Silent compiler warning. */
slen = strlen (MAIN_PAGE) + strlen (session->value_1);
reply = malloc (slen + 1);
if (NULL == reply)
return MHD_NO;
snprintf (reply,
slen + 1,
MAIN_PAGE,
session->value_1);
/* return static form */
response = MHD_create_response_from_buffer (slen,
(void *) reply,
MHD_RESPMEM_MUST_FREE);
if (NULL == response)
{
free (reply);
return MHD_NO;
}
add_session_cookie (session, response);
MHD_add_response_header (response,
MHD_HTTP_HEADER_CONTENT_ENCODING,
mime);
ret = MHD_queue_response (connection,
MHD_HTTP_OK,
response);
MHD_destroy_response (response);
return ret;
}
/**
* Handler that adds the 'v1' and 'v2' values to the given HTML code.
*
* @param cls unused
* @param mime mime type to use
* @param session session handle
* @param connection connection to use
*/
static int
fill_v1_v2_form (const void *cls,
const char *mime,
struct Session *session,
struct MHD_Connection *connection)
{
int ret;
char *reply;
struct MHD_Response *response;
size_t slen;
(void)cls; /* Unused. Silent compiler warning. */
slen = strlen (SECOND_PAGE) + strlen (session->value_1) + strlen (session->value_2);
reply = malloc (slen + 1);
if (NULL == reply)
return MHD_NO;
snprintf (reply,
slen + 1,
SECOND_PAGE,
session->value_1,
session->value_2);
/* return static form */
response = MHD_create_response_from_buffer (slen,
(void *) reply,
MHD_RESPMEM_MUST_FREE);
if (NULL == response)
{
free (reply);
return MHD_NO;
}
add_session_cookie (session, response);
MHD_add_response_header (response,
MHD_HTTP_HEADER_CONTENT_ENCODING,
mime);
ret = MHD_queue_response (connection,
MHD_HTTP_OK,
response);
MHD_destroy_response (response);
return ret;
}
/**
* Handler used to generate a 404 reply.
*
* @param cls a 'const char *' with the HTML webpage to return
* @param mime mime type to use
* @param session session handle
* @param connection connection to use
*/
static int
not_found_page (const void *cls,
const char *mime,
struct Session *session,
struct MHD_Connection *connection)
{
int ret;
struct MHD_Response *response;
(void)cls; /* Unused. Silent compiler warning. */
(void)session; /* Unused. Silent compiler warning. */
/* unsupported HTTP method */
response = MHD_create_response_from_buffer (strlen (NOT_FOUND_ERROR),
(void *) NOT_FOUND_ERROR,
MHD_RESPMEM_PERSISTENT);
if (NULL == response)
return MHD_NO;
ret = MHD_queue_response (connection,
MHD_HTTP_NOT_FOUND,
response);
MHD_add_response_header (response,
MHD_HTTP_HEADER_CONTENT_ENCODING,
mime);
MHD_destroy_response (response);
return ret;
}
/**
* List of all pages served by this HTTP server.
*/
static struct Page pages[] =
{
{ "/", "text/html", &fill_v1_form, NULL },
{ "/2", "text/html", &fill_v1_v2_form, NULL },
{ "/S", "text/html", &serve_simple_form, SUBMIT_PAGE },
{ "/F", "text/html", &serve_simple_form, LAST_PAGE },
{ NULL, NULL, ¬_found_page, NULL } /* 404 */
};
/**
* Iterator over key-value pairs where the value
* maybe made available in increments and/or may
* not be zero-terminated. Used for processing
* POST data.
*
* @param cls user-specified closure
* @param kind type of the value
* @param key 0-terminated key for the value
* @param filename name of the uploaded file, NULL if not known
* @param content_type mime-type of the data, NULL if not known
* @param transfer_encoding encoding of the data, NULL if not known
* @param data pointer to size bytes of data at the
* specified offset
* @param off offset of data in the overall value
* @param size number of bytes in data available
* @return MHD_YES to continue iterating,
* MHD_NO to abort the iteration
*/
static int
post_iterator (void *cls,
enum MHD_ValueKind kind,
const char *key,
const char *filename,
const char *content_type,
const char *transfer_encoding,
const char *data, uint64_t off, size_t size)
{
struct Request *request = cls;
struct Session *session = request->session;
(void)kind; /* Unused. Silent compiler warning. */
(void)filename; /* Unused. Silent compiler warning. */
(void)content_type; /* Unused. Silent compiler warning. */
(void)transfer_encoding; /* Unused. Silent compiler warning. */
if (0 == strcmp ("DONE", key))
{
fprintf (stdout,
"Session `%s' submitted `%s', `%s'\n",
session->sid,
session->value_1,
session->value_2);
return MHD_YES;
}
if (0 == strcmp ("v1", key))
{
if (size + off >= sizeof(session->value_1))
size = sizeof (session->value_1) - off - 1;
memcpy (&session->value_1[off],
data,
size);
session->value_1[size+off] = '\0';
return MHD_YES;
}
if (0 == strcmp ("v2", key))
{
if (size + off >= sizeof(session->value_2))
size = sizeof (session->value_2) - off - 1;
memcpy (&session->value_2[off],
data,
size);
session->value_2[size+off] = '\0';
return MHD_YES;
}
fprintf (stderr,
"Unsupported form value `%s'\n",
key);
return MHD_YES;
}
/**
* Main MHD callback for handling requests.
*
* @param cls argument given together with the function
* pointer when the handler was registered with MHD
* @param connection handle identifying the incoming connection
* @param url the requested url
* @param method the HTTP method used ("GET", "PUT", etc.)
* @param version the HTTP version string (i.e. "HTTP/1.1")
* @param upload_data the data being uploaded (excluding HEADERS,
* for a POST that fits into memory and that is encoded
* with a supported encoding, the POST data will NOT be
* given in upload_data and is instead available as
* part of MHD_get_connection_values; very large POST
* data *will* be made available incrementally in
* upload_data)
* @param upload_data_size set initially to the size of the
* upload_data provided; the method must update this
* value to the number of bytes NOT processed;
* @param ptr pointer that the callback can set to some
* address and that will be preserved by MHD for future
* calls for this request; since the access handler may
* be called many times (i.e., for a PUT/POST operation
* with plenty of upload data) this allows the application
* to easily associate some request-specific state.
* If necessary, this state can be cleaned up in the
* global "MHD_RequestCompleted" callback (which
* can be set with the MHD_OPTION_NOTIFY_COMPLETED).
* Initially, <tt>*con_cls</tt> will be NULL.
* @return MHS_YES if the connection was handled successfully,
* MHS_NO if the socket must be closed due to a serios
* error while handling the request
*/
static int
create_response (void *cls,
struct MHD_Connection *connection,
const char *url,
const char *method,
const char *version,
const char *upload_data,
size_t *upload_data_size,
void **ptr)
{
struct MHD_Response *response;
struct Request *request;
struct Session *session;
int ret;
unsigned int i;
(void)cls; /* Unused. Silent compiler warning. */
(void)version; /* Unused. Silent compiler warning. */
request = *ptr;
if (NULL == request)
{
request = calloc (1, sizeof (struct Request));
if (NULL == request)
{
fprintf (stderr, "calloc error: %s\n", strerror (errno));
return MHD_NO;
}
*ptr = request;
if (0 == strcmp (method, MHD_HTTP_METHOD_POST))
{
request->pp = MHD_create_post_processor (connection, 1024,
&post_iterator, request);
if (NULL == request->pp)
{
fprintf (stderr, "Failed to setup post processor for `%s'\n",
url);
return MHD_NO; /* internal error */
}
}
return MHD_YES;
}
if (NULL == request->session)
{
request->session = get_session (connection);
if (NULL == request->session)
{
fprintf (stderr, "Failed to setup session for `%s'\n",
url);
return MHD_NO; /* internal error */
}
}
session = request->session;
session->start = time (NULL);
if (0 == strcmp (method, MHD_HTTP_METHOD_POST))
{
/* evaluate POST data */
MHD_post_process (request->pp,
upload_data,
*upload_data_size);
if (0 != *upload_data_size)
{
*upload_data_size = 0;
return MHD_YES;
}
/* done with POST data, serve response */
MHD_destroy_post_processor (request->pp);
request->pp = NULL;
method = MHD_HTTP_METHOD_GET; /* fake 'GET' */
if (NULL != request->post_url)
url = request->post_url;
}
if ( (0 == strcmp (method, MHD_HTTP_METHOD_GET)) ||
(0 == strcmp (method, MHD_HTTP_METHOD_HEAD)) )
{
/* find out which page to serve */
i=0;
while ( (pages[i].url != NULL) &&
(0 != strcmp (pages[i].url, url)) )
i++;
ret = pages[i].handler (pages[i].handler_cls,
pages[i].mime,
session, connection);
if (ret != MHD_YES)
fprintf (stderr, "Failed to create page for `%s'\n",
url);
return ret;
}
/* unsupported HTTP method */
response = MHD_create_response_from_buffer (strlen (METHOD_ERROR),
(void *) METHOD_ERROR,
MHD_RESPMEM_PERSISTENT);
ret = MHD_queue_response (connection,
MHD_HTTP_NOT_ACCEPTABLE,
response);
MHD_destroy_response (response);
return ret;
}
/**
* Callback called upon completion of a request.
* Decrements session reference counter.
*
* @param cls not used
* @param connection connection that completed
* @param con_cls session handle
* @param toe status code
*/
static void
request_completed_callback (void *cls,
struct MHD_Connection *connection,
void **con_cls,
enum MHD_RequestTerminationCode toe)
{
struct Request *request = *con_cls;
(void)cls; /* Unused. Silent compiler warning. */
(void)connection; /* Unused. Silent compiler warning. */
(void)toe; /* Unused. Silent compiler warning. */
if (NULL == request)
return;
if (NULL != request->session)
request->session->rc--;
if (NULL != request->pp)
MHD_destroy_post_processor (request->pp);
free (request);
}
/**
* Clean up handles of sessions that have been idle for
* too long.
*/
static void
expire_sessions ()
{
struct Session *pos;
struct Session *prev;
struct Session *next;
time_t now;
now = time (NULL);
prev = NULL;
pos = sessions;
while (NULL != pos)
{
next = pos->next;
if (now - pos->start > 60 * 60)
{
/* expire sessions after 1h */
if (NULL == prev)
sessions = pos->next;
else
prev->next = next;
free (pos);
}
else
prev = pos;
pos = next;
}
}
/**
* Call with the port number as the only argument.
* Never terminates (other than by signals, such as CTRL-C).
*/
int
main (int argc, char *const *argv)
{
struct MHD_Daemon *d;
struct timeval tv;
struct timeval *tvp;
fd_set rs;
fd_set ws;
fd_set es;
MHD_socket max;
MHD_UNSIGNED_LONG_LONG mhd_timeout;
if (argc != 2)
{
printf ("%s PORT\n", argv[0]);
return 1;
}
/* initialize PRNG */
srand ((unsigned int) time (NULL));
d = MHD_start_daemon (MHD_USE_ERROR_LOG,
atoi (argv[1]),
NULL, NULL,
&create_response, NULL,
MHD_OPTION_CONNECTION_TIMEOUT, (unsigned int) 15,
MHD_OPTION_NOTIFY_COMPLETED, &request_completed_callback, NULL,
MHD_OPTION_END);
if (NULL == d)
return 1;
while (1)
{
expire_sessions ();
max = 0;
FD_ZERO (&rs);
FD_ZERO (&ws);
FD_ZERO (&es);
if (MHD_YES != MHD_get_fdset (d, &rs, &ws, &es, &max))
break; /* fatal internal error */
if (MHD_get_timeout (d, &mhd_timeout) == MHD_YES)
{
tv.tv_sec = mhd_timeout / 1000;
tv.tv_usec = (mhd_timeout - (tv.tv_sec * 1000)) * 1000;
tvp = &tv;
}
else
tvp = NULL;
if (-1 == select (max + 1, &rs, &ws, &es, tvp))
{
if (EINTR != errno)
abort ();
}
MHD_run (d);
}
MHD_stop_daemon (d);
return 0;
}