httpd.c

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/*
 * Copyright (c) 2001-2003 Swedish Institute of Computer Science.
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without modification,
 * are permitted provided that the following conditions are met:
 *
 * 1. Redistributions of source code must retain the above copyright notice,
 *    this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright notice,
 *    this list of conditions and the following disclaimer in the documentation
 *    and/or other materials provided with the distribution.
 * 3. The name of the author may not be used to endorse or promote products
 *    derived from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED
 * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
 * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT
 * SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT
 * OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING
 * IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY
 * OF SUCH DAMAGE.
 *
 * This file is part of the lwIP TCP/IP stack.
 *
 * Author: Adam Dunkels <[e-mail]>
 *
 */

/* This httpd supports for a
 * rudimentary server-side-include facility which will replace tags of the form
 * <!--#tag--> in any file whose extension is .shtml, .shtm or .ssi with
 * strings provided by an include handler whose pointer is provided to the
 * module via function http_set_ssi_handler().
 * Additionally, a simple common
 * gateway interface (CGI) handling mechanism has been added to allow clients
 * to hook functions to particular request URIs.
 *
 * To enable SSI support, define label LWIP_HTTPD_SSI in lwipopts.h.
 * To enable CGI support, define label LWIP_HTTPD_CGI in lwipopts.h.
 *
 * By default, the server assumes that HTTP headers are already present in
 * each file stored in the file system.  By defining LWIP_HTTPD_DYNAMIC_HEADERS in
 * lwipopts.h, this behavior can be changed such that the server inserts the
 * headers automatically based on the extension of the file being served.  If
 * this mode is used, be careful to ensure that the file system image used
 * does not already contain the header information.
 *
 * File system images without headers can be created using the makefsfile
 * tool with the -h command line option.
 *
 *
 * Notes about valid SSI tags
 * --------------------------
 *
 * The following assumptions are made about tags used in SSI markers:
 *
 * 1. No tag may contain '-' or whitespace characters within the tag name.
 * 2. Whitespace is allowed between the tag leadin "<!--#" and the start of
 *    the tag name and between the tag name and the leadout string "-->".
 * 3. The maximum tag name length is LWIP_HTTPD_MAX_TAG_NAME_LEN, currently 8 characters.
 *
 * Notes on CGI usage
 * ------------------
 *
 * The simple CGI support offered here works with GET method requests only
 * and can handle up to 16 parameters encoded into the URI. The handler
 * function may not write directly to the HTTP output but must return a
 * filename that the HTTP server will send to the browser as a response to
 * the incoming CGI request.
 *
 * @todo:
 * - don't use mem_malloc() (for SSI/dynamic headers)
 * - split too long functions into multiple smaller functions?
 * - support more file types?
 */
#include "lwip/debug.h"
#include "lwip/stats.h"
#include "httpd.h"
#include "httpd_structs.h"
#include "lwip/tcp.h"
#include "fs.h"

#include <string.h>
#include <stdlib.h>

#if LWIP_TCP

#ifndef HTTPD_DEBUG
#define HTTPD_DEBUG         LWIP_DBG_OFF
#endif

/** Set this to 1 and add the next line to lwippools.h to use a memp pool
 * for allocating struct http_state instead of the heap:
 *
 * LWIP_MEMPOOL(HTTPD_STATE, 20, 100, "HTTPD_STATE")
 */
#ifndef HTTPD_USE_MEM_POOL
#define HTTPD_USE_MEM_POOL  0
#endif

/** The server port for HTTPD to use */
#ifndef HTTPD_SERVER_PORT
#define HTTPD_SERVER_PORT                   80
#endif

/** Maximum retries before the connection is aborted/closed.
 * - number of times pcb->poll is called -> default is 4*500ms = 2s;
 * - reset when pcb->sent is called
 */
#ifndef HTTPD_MAX_RETRIES
#define HTTPD_MAX_RETRIES                   4
#endif

/** The poll delay is X*500ms */
#ifndef HTTPD_POLL_INTERVAL
#define HTTPD_POLL_INTERVAL                 4
#endif

/** Priority for tcp pcbs created by HTTPD (very low by default).
 *  Lower priorities get killed first when running out of memroy.
 */
#ifndef HTTPD_TCP_PRIO
#define HTTPD_TCP_PRIO                      TCP_PRIO_MIN
#endif

/** Set this to 1 to enabled timing each file sent */
#ifndef LWIP_HTTPD_TIMING
#define LWIP_HTTPD_TIMING                   0
#endif
#ifndef HTTPD_DEBUG_TIMING
#define HTTPD_DEBUG_TIMING                  LWIP_DBG_OFF
#endif

/** Set this to 1 on platforms where strnstr is not available */
#ifndef LWIP_HTTPD_STRNSTR_PRIVATE
#define LWIP_HTTPD_STRNSTR_PRIVATE          1
#endif

/** Set this to one to show error pages when parsing a request fails instead
    of simply closing the connection. */
#ifndef LWIP_HTTPD_SUPPORT_EXTSTATUS
#define LWIP_HTTPD_SUPPORT_EXTSTATUS        0
#endif

/** Set this to 0 to drop support for HTTP/0.9 clients (to save some bytes) */
#ifndef LWIP_HTTPD_SUPPORT_V09
#define LWIP_HTTPD_SUPPORT_V09              1
#endif

/** Set this to 1 to support HTTP request coming in in multiple packets/pbufs */
#ifndef LWIP_HTTPD_SUPPORT_REQUESTLIST
#define LWIP_HTTPD_SUPPORT_REQUESTLIST      0
#endif

#if LWIP_HTTPD_SUPPORT_REQUESTLIST
/** Number of rx pbufs to enqueue to parse an incoming request (up to the first
    newline) */
#ifndef LWIP_HTTPD_REQ_QUEUELEN
#define LWIP_HTTPD_REQ_QUEUELEN             10
#endif

/** Number of (TCP payload-) bytes (in pbufs) to enqueue to parse and incoming
    request (up to the first double-newline) */
#ifndef LWIP_HTTPD_REQ_BUFSIZE
#define LWIP_HTTPD_REQ_BUFSIZE              LWIP_HTTPD_MAX_REQ_LENGTH
#endif

/** Defines the maximum length of a HTTP request line (up to the first CRLF,
    copied from pbuf into this a global buffer when pbuf- or packet-queues
    are received - otherwise the input pbuf is used directly) */
#ifndef LWIP_HTTPD_MAX_REQ_LENGTH
#define LWIP_HTTPD_MAX_REQ_LENGTH           1023
#endif
#endif /* LWIP_HTTPD_SUPPORT_REQUESTLIST */

/** Maximum length of the filename to send as response to a POST request,
 * filled in by the application when a POST is finished.
 */
#ifndef LWIP_HTTPD_POST_MAX_RESPONSE_URI_LEN
#define LWIP_HTTPD_POST_MAX_RESPONSE_URI_LEN 63
#endif

/** Set this to 0 to not send the SSI tag (default is on, so the tag will
 * be sent in the HTML page */
#ifndef LWIP_HTTPD_SSI_INCLUDE_TAG
#define LWIP_HTTPD_SSI_INCLUDE_TAG           1
#endif

/** Set this to 1 to call tcp_abort when tcp_close fails with memory error.
 * This can be used to prevent consuming all memory in situations where the
 * HTTP server has low priority compared to other communication. */
#ifndef LWIP_HTTPD_ABORT_ON_CLOSE_MEM_ERROR
#define LWIP_HTTPD_ABORT_ON_CLOSE_MEM_ERROR  0
#endif

#ifndef true
#define true ((u8_t)1)
#endif

#ifndef false
#define false ((u8_t)0)
#endif

/** Minimum length for a valid HTTP/0.9 request: "GET /\r\n" -> 7 bytes */
#define MIN_REQ_LEN   7

#define CRLF "\r\n"

/** These defines check whether tcp_write has to copy data or not */

/** This was TI's check whether to let TCP copy data or not
#define HTTP_IS_DATA_VOLATILE(hs) ((hs->file < (char *)0x20000000) ? 0 : TCP_WRITE_FLAG_COPY)*/
#ifndef HTTP_IS_DATA_VOLATILE
#if LWIP_HTTPD_SSI
/* Copy for SSI files, no copy for non-SSI files */
#define HTTP_IS_DATA_VOLATILE(hs)   ((hs)->tag_check ? TCP_WRITE_FLAG_COPY : 0)
#else /* LWIP_HTTPD_SSI */
/** Default: don't copy if the data is sent from file-system directly */
#define HTTP_IS_DATA_VOLATILE(hs) (((hs->file != NULL) && (hs->handle != NULL) && (hs->file == \
                                   (char*)hs->handle->data + hs->handle->len - hs->left)) \
                                   ? 0 : TCP_WRITE_FLAG_COPY)
#endif /* LWIP_HTTPD_SSI */
#endif

/** Default: headers are sent from ROM */
#ifndef HTTP_IS_HDR_VOLATILE
#define HTTP_IS_HDR_VOLATILE(hs, ptr) 0
#endif

#if LWIP_HTTPD_SSI
/** Default: Tags are sent from struct http_state and are therefore volatile */
#ifndef HTTP_IS_TAG_VOLATILE
#define HTTP_IS_TAG_VOLATILE(ptr) TCP_WRITE_FLAG_COPY
#endif
#endif /* LWIP_HTTPD_SSI */

typedef struct
{
  const char *name;
  u8_t shtml;
} default_filename;

const default_filename g_psDefaultFilenames[] = {
  {"/index.shtml", true },
  {"/index.ssi", true },
  {"/index.shtm", true },
  {"/index.html", false },
  {"/index.htm", false }
};

#define NUM_DEFAULT_FILENAMES (sizeof(g_psDefaultFilenames) /   \
                               sizeof(default_filename))

#if LWIP_HTTPD_SUPPORT_REQUESTLIST
/** HTTP request is copied here from pbufs for simple parsing */
static char httpd_req_buf[LWIP_HTTPD_MAX_REQ_LENGTH+1];
#endif /* LWIP_HTTPD_SUPPORT_REQUESTLIST */

#if LWIP_HTTPD_SUPPORT_POST
/** Filename for response file to send when POST is finished */
static char http_post_response_filename[LWIP_HTTPD_POST_MAX_RESPONSE_URI_LEN+1];
#endif /* LWIP_HTTPD_SUPPORT_POST */

#if LWIP_HTTPD_DYNAMIC_HEADERS
/* The number of individual strings that comprise the headers sent before each
 * requested file.
 */
#define NUM_FILE_HDR_STRINGS 3
#endif /* LWIP_HTTPD_DYNAMIC_HEADERS */

#if LWIP_HTTPD_SSI

#define HTTPD_LAST_TAG_PART 0xFFFF

const char * const g_pcSSIExtensions[] = {
  ".shtml", ".shtm", ".ssi", ".xml"
};

#define NUM_SHTML_EXTENSIONS (sizeof(g_pcSSIExtensions) / sizeof(const char *))

enum tag_check_state {
  TAG_NONE,       /* Not processing an SSI tag */
  TAG_LEADIN,     /* Tag lead in "<!--#" being processed */
  TAG_FOUND,      /* Tag name being read, looking for lead-out start */
  TAG_LEADOUT,    /* Tag lead out "-->" being processed */
  TAG_SENDING     /* Sending tag replacement string */
};
#endif /* LWIP_HTTPD_SSI */

struct http_state {
  struct fs_file *handle;
  char *file;       /* Pointer to first unsent byte in buf. */

#if LWIP_HTTPD_SUPPORT_REQUESTLIST
  struct pbuf *req;
#endif /* LWIP_HTTPD_SUPPORT_REQUESTLIST */

#if LWIP_HTTPD_SSI || LWIP_HTTPD_DYNAMIC_HEADERS
  char *buf;        /* File read buffer. */
  int buf_len;      /* Size of file read buffer, buf. */
#endif /* LWIP_HTTPD_SSI || LWIP_HTTPD_DYNAMIC_HEADERS */
  u32_t left;       /* Number of unsent bytes in buf. */
  u8_t retries;
#if LWIP_HTTPD_SSI
  const char *parsed;     /* Pointer to the first unparsed byte in buf. */
#if !LWIP_HTTPD_SSI_INCLUDE_TAG
  const char *tag_started;/* Poitner to the first opening '<' of the tag. */
#endif /* !LWIP_HTTPD_SSI_INCLUDE_TAG */
  const char *tag_end;    /* Pointer to char after the closing '>' of the tag. */
  u32_t parse_left; /* Number of unparsed bytes in buf. */
  u16_t tag_index;   /* Counter used by tag parsing state machine */
  u16_t tag_insert_len; /* Length of insert in string tag_insert */
#if LWIP_HTTPD_SSI_MULTIPART
  u16_t tag_part; /* Counter passed to and changed by tag insertion function to insert multiple times */
#endif /* LWIP_HTTPD_SSI_MULTIPART */
  u8_t tag_check;   /* true if we are processing a .shtml file else false */
  u8_t tag_name_len; /* Length of the tag name in string tag_name */
  char tag_name[LWIP_HTTPD_MAX_TAG_NAME_LEN + 1]; /* Last tag name extracted */
  char tag_insert[LWIP_HTTPD_MAX_TAG_INSERT_LEN + 1]; /* Insert string for tag_name */
  enum tag_check_state tag_state; /* State of the tag processor */
#endif /* LWIP_HTTPD_SSI */
#if LWIP_HTTPD_CGI
  char *params[LWIP_HTTPD_MAX_CGI_PARAMETERS]; /* Params extracted from the request URI */
  char *param_vals[LWIP_HTTPD_MAX_CGI_PARAMETERS]; /* Values for each extracted param */
#endif /* LWIP_HTTPD_CGI */
#if LWIP_HTTPD_DYNAMIC_HEADERS
  const char *hdrs[NUM_FILE_HDR_STRINGS]; /* HTTP headers to be sent. */
  u16_t hdr_pos;     /* The position of the first unsent header byte in the
                        current string */
  u16_t hdr_index;   /* The index of the hdr string currently being sent. */
#endif /* LWIP_HTTPD_DYNAMIC_HEADERS */
#if LWIP_HTTPD_TIMING
  u32_t time_started;
#endif /* LWIP_HTTPD_TIMING */
#if LWIP_HTTPD_SUPPORT_POST
  u32_t post_content_len_left;
#if LWIP_HTTPD_POST_MANUAL_WND
  u32_t unrecved_bytes;
  struct tcp_pcb *pcb;
  u8_t no_auto_wnd;
#endif /* LWIP_HTTPD_POST_MANUAL_WND */
#endif /* LWIP_HTTPD_SUPPORT_POST*/
};

static err_t http_find_file(struct http_state *hs, const char *uri, int is_09);
static err_t http_init_file(struct http_state *hs, struct fs_file *file, int is_09, const char *uri);
static err_t http_poll(void *arg, struct tcp_pcb *pcb);

#if LWIP_HTTPD_SSI
/* SSI insert handler function pointer. */
tSSIHandler g_pfnSSIHandler = NULL;
int g_iNumTags = 0;
const char **g_ppcTags = NULL;

#define LEN_TAG_LEAD_IN 5
const char * const g_pcTagLeadIn = "<!--#";

#define LEN_TAG_LEAD_OUT 3
const char * const g_pcTagLeadOut = "-->";
#endif /* LWIP_HTTPD_SSI */

#if LWIP_HTTPD_CGI
/* CGI handler information */
const tCGI *g_pCGIs;
int g_iNumCGIs;
#endif /* LWIP_HTTPD_CGI */

#if LWIP_HTTPD_STRNSTR_PRIVATE
/** Like strstr but does not need 'buffer' to be NULL-terminated */
static char*