mod_isapi.c

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 * on public domain software written at the National Center for
 * Supercomputing Applications, University of Illinois, Urbana-Champaign.
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/*
 * mod_isapi.c - Internet Server Application (ISA) module for Apache
 * by Alexei Kosut <[e-mail]>
 *
 * This module implements Microsoft's ISAPI, allowing Apache (when running
 * under Windows) to load Internet Server Applications (ISAPI extensions).
 * It implements all of the ISAPI 2.0 specification, except for the 
 * "Microsoft-only" extensions dealing with asynchronous I/O. All ISAPI
 * extensions that use only synchronous I/O and are compatible with the
 * ISAPI 2.0 specification should work (most ISAPI 1.0 extensions should
 * function as well).
 *
 * To load, simply place the ISA in a location in the document tree.
 * Then add an "AddHandler isapi-isa dll" into your config file.
 * You should now be able to load ISAPI DLLs just be reffering to their
 * URLs. Make sure the ExecCGI option is active in the directory
 * the ISA is in.
 */

#include "httpd.h"
#include "http_config.h"
#include "http_core.h"
#include "http_protocol.h"
#include "http_request.h"
#include "http_log.h"
#include "util_script.h"

/* We use the exact same header file as the original */
#include <HttpExt.h>

/* Seems IIS does not enforce the requirement for \r\n termination on HSE_REQ_SEND_RESPONSE_HEADER,
   define this to conform */
#define RELAX_HEADER_RULE

module isapi_module;

/* Our "Connection ID" structure */

typedef struct {
    LPEXTENSION_CONTROL_BLOCK ecb;
    request_rec *r;
    int status;
} isapi_cid;

/* Declare the ISAPI functions */

BOOL WINAPI GetServerVariable (HCONN hConn, LPSTR lpszVariableName,
			       LPVOID lpvBuffer, LPDWORD lpdwSizeofBuffer);
BOOL WINAPI WriteClient (HCONN ConnID, LPVOID Buffer, LPDWORD lpwdwBytes,
			 DWORD dwReserved);
BOOL WINAPI ReadClient (HCONN ConnID, LPVOID lpvBuffer, LPDWORD lpdwSize);
BOOL WINAPI ServerSupportFunction (HCONN hConn, DWORD dwHSERequest,
				   LPVOID lpvBuffer, LPDWORD lpdwSize,
				   LPDWORD lpdwDataType);

/*
    The optimiser blows it totally here. What happens is that autos are addressed relative to the
    stack pointer, which, of course, moves around. The optimiser seems to lose track of it somewhere
    between setting isapi_entry and calling through it. We work around the problem by forcing it to
    use frame pointers.
*/
#pragma optimize("y",off)

int isapi_handler (request_rec *r) {
    LPEXTENSION_CONTROL_BLOCK ecb =
	ap_pcalloc(r->pool, sizeof(struct _EXTENSION_CONTROL_BLOCK));
    HSE_VERSION_INFO *pVer = ap_pcalloc(r->pool, sizeof(HSE_VERSION_INFO));

    HINSTANCE isapi_handle;
    BOOL (*isapi_version)(HSE_VERSION_INFO *); /* entry point 1 */
    DWORD (*isapi_entry)(LPEXTENSION_CONTROL_BLOCK); /* entry point 2 */
    BOOL (*isapi_term)(DWORD); /* optional entry point 3 */

    isapi_cid *cid = ap_pcalloc(r->pool, sizeof(isapi_cid));
    table *e = r->subprocess_env;
    int retval;

    /* Use similar restrictions as CGIs */

    if (!(ap_allow_options(r) & OPT_EXECCGI))
	return FORBIDDEN;

    if (r->finfo.st_mode == 0)
	return NOT_FOUND;

    if (S_ISDIR(r->finfo.st_mode))
	return FORBIDDEN;

    /* Load the module */

    if (!(isapi_handle = LoadLibraryEx(r->filename, NULL,
				       LOAD_WITH_ALTERED_SEARCH_PATH))) {
	ap_log_rerror(APLOG_MARK, APLOG_ALERT, r,
		    "Could not load DLL: %s", r->filename);
	return SERVER_ERROR;
    }

    if (!(isapi_version =
	  (void *)(GetProcAddress(isapi_handle, "GetExtensionVersion")))) {
	ap_log_rerror(APLOG_MARK, APLOG_ALERT, r,
		    "DLL could not load GetExtensionVersion(): %s", r->filename);
	FreeLibrary(isapi_handle);
	return SERVER_ERROR;
    }

    if (!(isapi_entry =
	  (void *)(GetProcAddress(isapi_handle, "HttpExtensionProc")))) {
	ap_log_rerror(APLOG_MARK, APLOG_ALERT, r,
		    "DLL could not load HttpExtensionProc(): %s", r->filename);
	FreeLibrary(isapi_handle);
	return SERVER_ERROR;
    }

    isapi_term = (void *)(GetProcAddress(isapi_handle, "TerminateExtension"));

    /* Run GetExtensionVersion() */

    if ((*isapi_version)(pVer) != TRUE) {
	ap_log_rerror(APLOG_MARK, APLOG_ALERT, r,
		    "ISAPI GetExtensionVersion() failed: %s", r->filename);
	FreeLibrary(isapi_handle);
	return SERVER_ERROR;
    }

    /* Set up variables */
    ap_add_common_vars(r);
    ap_add_cgi_vars(r);

    /* Set up connection ID */
    ecb->ConnID = (HCONN)cid;
    cid->ecb = ecb;
    cid->r = r;
    cid->status = 0;

    ecb->cbSize = sizeof(struct _EXTENSION_CONTROL_BLOCK);
    ecb->dwVersion = MAKELONG(0, 2);
    ecb->dwHttpStatusCode = 0;
    strcpy(ecb->lpszLogData, "");
    ecb->lpszMethod = r->method;
    ecb->lpszQueryString = ap_table_get(e, "QUERY_STRING");
    ecb->lpszPathInfo = ap_table_get(e, "PATH_INFO");
    ecb->lpszPathTranslated = ap_table_get(e, "PATH_TRANSLATED");
    ecb->lpszContentType = ap_table_get(e, "CONTENT_TYPE");

    /* Set up client input */
    if ((retval = ap_setup_client_block(r, REQUEST_CHUNKED_ERROR))) {
	if (isapi_term) (*isapi_term)(HSE_TERM_MUST_UNLOAD);
	FreeLibrary(isapi_handle);
	return retval;
    }

    if (ap_should_client_block(r)) {
	/* Unlike IIS, which limits this to 48k, we read the whole
	 * sucker in. I suppose this could be bad for memory if someone
	 * uploaded the complete works of Shakespeare. Well, WebSite
	 * does the same thing.
	 */
	long to_read = atol(ap_table_get(e, "CONTENT_LENGTH"));
	long read;

	/* Actually, let's cap it at 48k, until we figure out what
	 * to do with this... we don't want a Content-Length: 1000000000
	 * taking out the machine.
	 */

	if (to_read > 49152) {
	    if (isapi_term) (*isapi_term)(HSE_TERM_MUST_UNLOAD);
	    FreeLibrary(isapi_handle);
	    return HTTP_REQUEST_ENTITY_TOO_LARGE;
	}

	ecb->lpbData = ap_pcalloc(r->pool, 1 + to_read);

	if ((read = ap_get_client_block(r, ecb->lpbData, to_read)) < 0) {
	    if (isapi_term) (*isapi_term)(HSE_TERM_MUST_UNLOAD);
	    FreeLibrary(isapi_handle);
	    return SERVER_ERROR;
	}

	/* Although its not to spec, IIS seems to null-terminate
	 * its lpdData string. So we will too. To make sure
	 * cbAvailable matches cbTotalBytes, we'll up the latter
	 * and equalize them.
	 */
	ecb->cbAvailable = ecb->cbTotalBytes = read + 1;
	ecb->lpbData[read] = '\0';
	}
    else {
	ecb->cbTotalBytes = 0;
	ecb->cbAvailable = 0;
	ecb->lpbData = NULL;
    }

    /* Set up the callbacks */

    ecb->GetServerVariable = &GetServerVariable;
    ecb->WriteClient = &WriteClient;
    ecb->ReadClient = &ReadClient;
    ecb->ServerSupportFunction = &ServerSupportFunction;

    /* All right... try and load the sucker */
    retval = (*isapi_entry)(ecb);

    /* Set the status (for logging) */
    if (ecb->dwHttpStatusCode)
	r->status = ecb->dwHttpStatusCode;

    /* Check for a log message - and log it */
    if (ecb->lpszLogData && strcmp(ecb->lpszLogData, ""))
	ap_log_rerror(APLOG_MARK, APLOG_ERR, r,
		    "%s: %s", ecb->lpszLogData, r->filename);

    /* All done with the DLL... get rid of it */
    if (isapi_term) (*isapi_term)(HSE_TERM_MUST_UNLOAD);
    FreeLibrary(isapi_handle);

    switch(retval) {
    case HSE_STATUS_SUCCESS:
    case HSE_STATUS_SUCCESS_AND_KEEP_CONN:
	/* Ignore the keepalive stuff; Apache handles it just fine without
	 * the ISA's "advice".
	 */

	if (cid->status) /* We have a special status to return */
	    return cid->status;

	return OK;
    case HSE_STATUS_PENDING:	/* We don't support this */