/*
 * $Id: errorpage.c,v 1.188 2006/08/25 12:26:07 serassio Exp $
 *
 * DEBUG: section 4     Error Generation
 * AUTHOR: Duane Wessels
 *
 * SQUID Web Proxy Cache          http://www.squid-cache.org/
 * ----------------------------------------------------------
 *
 *  Squid is the result of efforts by numerous individuals from
 *  the Internet community; see the CONTRIBUTORS file for full
 *  details.   Many organizations have provided support for Squid's
 *  development; see the SPONSORS file for full details.  Squid is
 *  Copyrighted (C) 2001 by the Regents of the University of
 *  California; see the COPYRIGHT file for full details.  Squid
 *  incorporates software developed and/or copyrighted by other
 *  sources; see the CREDITS file for full details.
 *
 *  This program is free software; you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License as published by
 *  the Free Software Foundation; either version 2 of the License, or
 *  (at your option) any later version.
 *  
 *  This program 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 General Public License for more details.
 *  
 *  You should have received a copy of the GNU General Public License
 *  along with this program; if not, write to the Free Software
 *  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111, USA.
 *
 */

/*
 * Abstract:  These routines are used to generate error messages to be
 *              sent to clients.  The error type is used to select between
 *              the various message formats. (formats are stored in the
 *              Config.errorDirectory)
 */

#include "squid.h"


/* local types */

typedef struct {
    int id;
    char *page_name;
} ErrorDynamicPageInfo;

/* local constant and vars */

/*
 * note: hard coded error messages are not appended with %S automagically
 * to give you more control on the format
 */
static const struct {
    int type;			/* and page_id */
    const char *text;
} error_hard_text[] = {

    {
	ERR_SQUID_SIGNATURE,
	    "\n<BR clear=\"all\">\n"
	    "<HR noshade size=\"1px\">\n"
	    "<ADDRESS>\n"
	    "Generated %T by %h (%s)\n"
	    "</ADDRESS>\n"
	    "</BODY></HTML>\n"
    },
    {
	TCP_RESET,
	    "reset"
    }
};

static Stack ErrorDynamicPages;

/* local prototypes */

static const int error_hard_text_count = sizeof(error_hard_text) / sizeof(*error_hard_text);
static char **error_text = NULL;
static int error_page_count = 0;

static char *errorTryLoadText(const char *page_name, const char *dir);
static char *errorLoadText(const char *page_name);
static const char *errorFindHardText(err_type type);
static ErrorDynamicPageInfo *errorDynamicPageInfoCreate(int id, const char *page_name);
static void errorDynamicPageInfoDestroy(ErrorDynamicPageInfo * info);
static MemBuf errorBuildContent(ErrorState * err);
static const char *errorConvert(char token, ErrorState * err);
static CWCB errorSendComplete;

/*
 * Function:  errorInitialize
 *
 * Abstract:  This function finds the error messages formats, and stores
 *            them in error_text[];
 *
 * Global effects:
 *            error_text[] - is modified
 */
void
errorInitialize(void)
{
    err_type i;
    const char *text;
    error_page_count = ERR_MAX + ErrorDynamicPages.count;
    error_text = xcalloc(error_page_count, sizeof(char *));
    for (i = ERR_NONE, i++; i < error_page_count; i++) {
	safe_free(error_text[i]);
	/* hard-coded ? */
	if ((text = errorFindHardText(i)))
	    error_text[i] = xstrdup(text);
	else if (i < ERR_MAX) {
	    /* precompiled ? */
	    error_text[i] = errorLoadText(err_type_str[i]);
	} else {
	    /* dynamic */
	    ErrorDynamicPageInfo *info = ErrorDynamicPages.items[i - ERR_MAX];
	    assert(info && info->id == i && info->page_name);
	    if (strchr(info->page_name, ':') == NULL) {
		/* Not on redirected errors... */
		error_text[i] = errorLoadText(info->page_name);
	    }
	}
    }
}

void
errorClean(void)
{
    if (error_text) {
	int i;
	for (i = ERR_NONE + 1; i < error_page_count; i++)
	    safe_free(error_text[i]);
	safe_free(error_text);
    }
    while (ErrorDynamicPages.count)
	errorDynamicPageInfoDestroy(stackPop(&ErrorDynamicPages));
    error_page_count = 0;
}

static const char *
errorFindHardText(err_type type)
{
    int i;
    for (i = 0; i < error_hard_text_count; i++)
	if (error_hard_text[i].type == type)
	    return error_hard_text[i].text;
    return NULL;
}


static char *
errorLoadText(const char *page_name)
{
    /* test configured location */
    char *text = errorTryLoadText(page_name, Config.errorDirectory);
    /* test default location if failed */
    if (!text && strcmp(Config.errorDirectory, DEFAULT_SQUID_ERROR_DIR))
	text = errorTryLoadText(page_name, DEFAULT_SQUID_ERROR_DIR);
    /* giving up if failed */
    if (!text)
	fatal("failed to find or read error text file.");
    return text;
}

static char *
errorTryLoadText(const char *page_name, const char *dir)
{
    int fd;
    char path[MAXPATHLEN];
    struct stat sb;
    char *text;

    snprintf(path, sizeof(path), "%s/%s", dir, page_name);
#ifdef _SQUID_MSWIN_
    fd = file_open(path, O_RDONLY | O_BINARY);
#else
    fd = file_open(path, O_RDONLY | O_TEXT);
#endif
    if (fd < 0 || fstat(fd, &sb) < 0) {
	debug(4, 0) ("errorTryLoadText: '%s': %s\n", path, xstrerror());
	if (fd >= 0)
	    file_close(fd);
	return NULL;
    }
    text = xcalloc((size_t) sb.st_size + 2 + 1, 1);	/* 2 == space for %S */
    if (FD_READ_METHOD(fd, text, (int) sb.st_size) != sb.st_size) {
	debug(4, 0) ("errorTryLoadText: failed to fully read: '%s': %s\n",
	    path, xstrerror());
	safe_free(text);
    }
    file_close(fd);
    if (text && strstr(text, "%s") == NULL)
	strcat(text, "%S");	/* add signature */
    return text;
}

static ErrorDynamicPageInfo *
errorDynamicPageInfoCreate(int id, const char *page_name)
{
    ErrorDynamicPageInfo *info = xcalloc(1, sizeof(ErrorDynamicPageInfo));
    info->id = id;
    info->page_name = xstrdup(page_name);
    return info;
}

static void
errorDynamicPageInfoDestroy(ErrorDynamicPageInfo * info)
{
    assert(info);
    xfree(info->page_name);
    xfree(info);
}

int
errorPageId(const char *page_name)
{
    int i;
    for (i = 0; i < ERR_MAX; i++) {
	if (strcmp(err_type_str[i], page_name) == 0)
	    return i;
    }
    for (i = 0; i < ErrorDynamicPages.count; i++) {
	if (strcmp(((ErrorDynamicPageInfo *) ErrorDynamicPages.items[i])->page_name, page_name) == 0)
	    return i + ERR_MAX;
    }
    return ERR_NONE;
}

int
errorReservePageId(const char *page_name)
{
    ErrorDynamicPageInfo *info;
    int id = errorPageId(page_name);
    if (id == ERR_NONE) {
	info = errorDynamicPageInfoCreate(ERR_MAX + ErrorDynamicPages.count, page_name);
	stackPush(&ErrorDynamicPages, info);
	id = info->id;
    }
    return id;
}

static const char *
errorPageName(int pageId)
{
    if (pageId >= ERR_NONE && pageId < ERR_MAX)		/* common case */
	return err_type_str[pageId];
    if (pageId >= ERR_MAX && pageId - ERR_MAX < ErrorDynamicPages.count)
	return ((ErrorDynamicPageInfo *) ErrorDynamicPages.items[pageId - ERR_MAX])->page_name;
    return "ERR_UNKNOWN";	/* should not happen */
}

/*
 * Function:  errorCon
 *
 * Abstract:  This function creates a ErrorState object.
 */
ErrorState *
errorCon(err_type type, http_status status, request_t * request)
{
    ErrorState *err;
    err = cbdataAlloc(ErrorState);
    err->page_id = type;	/* has to be reset manually if needed */
    err->type = type;
    err->http_status = status;
    if (request != NULL) {
	err->request = requestLink(request);
	err->src_addr = request->client_addr;
    }
    return err;
}

/*
 * Function:  errorAppendEntry
 *
 * Arguments: err - This object is destroyed after use in this function.
 *
 * Abstract:  This function generates a error page from the info contained
 *            by 'err' and then stores the text in the specified store
 *            entry.  This function should only be called by ``server
 *            side routines'' which need to communicate errors to the
 *            client side.  It should also be called from client_side.c
 *            because we now support persistent connections, and
 *            cannot assume that we can immediately write to the socket
 *            for an error.
 */
void
errorAppendEntry(StoreEntry * entry, ErrorState * err)
{
    HttpReply *rep;
    MemObject *mem = entry->mem_obj;
    assert(mem != NULL);
    assert(mem->inmem_hi == 0);
    if (entry->store_status != STORE_PENDING) {
	/*
	 * If the entry is not STORE_PENDING, then no clients
	 * care about it, and we don't need to generate an
	 * error message
	 */
	assert(EBIT_TEST(entry->flags, ENTRY_ABORTED));
	assert(mem->nclients == 0);
	errorStateFree(err);
	return;
    }
    if (err->page_id == TCP_RESET) {
	if (err->request) {
	    debug(4, 2) ("RSTing this reply\n");
	    err->request->flags.reset_tcp = 1;
	}
    }
    storeLockObject(entry);
    storeBuffer(entry);
    rep = errorBuildReply(err);
    /* Add authentication header */
    /* TODO: alter errorstate to be accel on|off aware. The 0 on the next line
     * depends on authenticate behaviour: all schemes to date send no extra data
     * on 407/401 responses, and do not check the accel state on 401/407 responses 
     */
    authenticateFixHeader(rep, err->auth_user_request, err->request, 0, 1);
    httpReplySwapOut(rep, entry);
    EBIT_CLR(entry->flags, ENTRY_FWD_HDR_WAIT);
    storeBufferFlush(entry);
    storeComplete(entry);
    storeNegativeCache(entry);
    storeReleaseRequest(entry);
    storeUnlockObject(entry);
    errorStateFree(err);
}

/*
 * Function:  errorSend
 *
 * Arguments: err - This object is destroyed after use in this function.
 *
 * Abstract:  This function generates a error page from the info contained
 *            by 'err' and then sends it to the client.
 *            The callback function errorSendComplete() is called after
 *            the page has been written to the client socket (fd).
 *            errorSendComplete() deallocates 'err'.  We need to add
 *            'err' to the cbdata because comm_write() requires it
 *            for all callback data pointers.
 *
 *            Note, normally errorSend() should only be called from
 *            routines in ssl.c and pass.c, where we don't have any
 *            StoreEntry's.  In client_side.c we must allocate a StoreEntry
 *            for errors and use errorAppendEntry() to account for
 *            persistent/pipeline connections.
 */
void
errorSend(int fd, ErrorState * err)
{
    HttpReply *rep;
    debug(4, 3) ("errorSend: FD %d, err=%p\n", fd, err);
    assert(fd >= 0);
    /*
     * ugh, this is how we make sure error codes get back to
     * the client side for logging and error tracking.
     */
    if (err->request)
	err->request->err_type = err->type;
    /* moved in front of errorBuildBuf @?@ */
    err->flags.flag_cbdata = 1;
    rep = errorBuildReply(err);
    comm_write_mbuf(fd, httpReplyPack(rep), errorSendComplete, err);
    httpReplyDestroy(rep);
}

/*
 * Function:  errorSendComplete
 *
 * Abstract:  Called by commHandleWrite() after data has been written
 *            to the client socket.
 *
 * Note:      If there is a callback, the callback is responsible for
 *            closeing the FD, otherwise we do it ourseves.
 */
static void
errorSendComplete(int fd, char *bufnotused, size_t size, int errflag, void *data)
{
    ErrorState *err = data;
    debug(4, 3) ("errorSendComplete: FD %d, size=%ld\n", fd, (long int) size);
    if (errflag != COMM_ERR_CLOSING) {
	if (err->callback) {
	    debug(4, 3) ("errorSendComplete: callback\n");
	    err->callback(fd, err->callback_data, size);
	} else {
	    comm_close(fd);
	    debug(4, 3) ("errorSendComplete: comm_close\n");
	}
    }
    errorStateFree(err);
}

void
errorStateFree(ErrorState * err)
{
    requestUnlink(err->request);
    safe_free(err->redirect_url);
    safe_free(err->url);
    safe_free(err->dnsserver_msg);
    safe_free(err->request_hdrs);
    wordlistDestroy(&err->ftp.server_msg);
    safe_free(err->ftp.request);
    safe_free(err->ftp.reply);
    if (err->auth_user_request)
	authenticateAuthUserRequestUnlock(err->auth_user_request);
    err->auth_user_request = NULL;
    cbdataFree(err);
}

#define CVT_BUF_SZ 512

/*
 * a - User identity                            x
 * B - URL with FTP %2f hack                    x
 * c - Squid error code                         x
 * e - errno                                    x
 * E - strerror()                               x
 * f - FTP request line                         x
 * F - FTP reply line                           x
 * g - FTP server message                       x
 * h - cache hostname                           x
 * H - server host name                         x
 * i - client IP address                        x
 * I - server IP address                        x
 * L - HREF link for more info/contact          x
 * M - Request Method                           x
 * m - Error message returned by external Auth. x 
 * o - Error message returned by external ACL   x
 * p - URL port #                               x
 * P - Protocol                                 x
 * R - Full HTTP Request                        x
 * S - squid signature from ERR_SIGNATURE       x
 * s - caching proxy software with version      x
 * t - local time                               x
 * T - UTC                                      x
 * U - URL without password                     x
 * u - URL with password                        x
 * w - cachemgr email address                   x
 * z - dns server error message                 x
 */

static const char *
errorConvert(char token, ErrorState * err)
{
    request_t *r = err->request;
    static MemBuf mb = MemBufNULL;
    const char *p = NULL;	/* takes priority over mb if set */
    int do_quote = 1;

    memBufReset(&mb);
    switch (token) {
    case 'a':
	if (r && r->auth_user_request)
	    p = authenticateUserRequestUsername(r->auth_user_request);
	if (!p)
	    p = "-";
	break;
    case 'B':
	p = r ? ftpUrlWith2f(r) : "[no URL]";
	break;
    case 'c':
	p = errorPageName(err->type);
	break;
    case 'e':
	memBufPrintf(&mb, "%d", err->xerrno);
	break;
    case 'E':
	if (err->xerrno)
	    memBufPrintf(&mb, "(%d) %s", err->xerrno, strerror(err->xerrno));
	else
	    memBufPrintf(&mb, "[No Error]");
	break;
    case 'f':
	/* FTP REQUEST LINE */
	if (err->ftp.request)
	    p = err->ftp.request;
	else
	    p = "nothing";
	break;
    case 'F':
	/* FTP REPLY LINE */
	if (err->ftp.request)
	    p = err->ftp.reply;
	else
	    p = "nothing";
	break;
    case 'g':
	/* FTP SERVER MESSAGE */
	wordlistCat(err->ftp.server_msg, &mb);
	break;
    case 'h':
	memBufPrintf(&mb, "%s", getMyHostname());
	break;
    case 'H':
	if (r) {
	    if (r->hier.host)
		p = r->hier.host;
	    else
		p = r->host;
	} else
	    p = "[unknown host]";
	break;
    case 'i':
	memBufPrintf(&mb, "%s", inet_ntoa(err->src_addr));
	break;
    case 'I':
	if (r && r->hier.host) {
	    memBufPrintf(&mb, "%s", r->hier.host);
	} else
	    p = "[unknown]";
	break;
    case 'L':
	if (Config.errHtmlText) {
	    memBufPrintf(&mb, "%s", Config.errHtmlText);
	    do_quote = 0;
	} else
	    p = "[not available]";
	break;
    case 'm':
	p = authenticateAuthUserRequestMessage(err->auth_user_request) ? authenticateAuthUserRequestMessage(err->auth_user_request) : "[not available]";
	break;
    case 'M':
	p = r ? RequestMethodStr[r->method] : "[unkown method]";
	break;
    case 'o':
	p = external_acl_message;
	if (!p)
	    p = "[not available]";
	break;
    case 'p':
	if (r) {
	    memBufPrintf(&mb, "%d", (int) r->port);
	} else {
	    p = "[unknown port]";
	}
	break;
    case 'P':
	p = r ? ProtocolStr[r->protocol] : "[unkown protocol]";
	break;
    case 'R':
	if (NULL != r) {
	    Packer p;
	    memBufPrintf(&mb, "%s %s HTTP/%d.%d\n",
		RequestMethodStr[r->method],
		strLen(r->urlpath) ? strBuf(r->urlpath) : "/",
		r->http_ver.major, r->http_ver.minor);
	    packerToMemInit(&p, &mb);
	    httpHeaderPackInto(&r->header, &p);
	    packerClean(&p);
	} else if (err->request_hdrs) {
	    p = err->request_hdrs;
	} else {
	    p = "[no request]";
	}
	break;
    case 's':
	p = visible_appname_string;
	break;
    case 'S':
	/* signature may contain %-escapes, recursion */
	if (err->page_id != ERR_SQUID_SIGNATURE) {
	    const int saved_id = err->page_id;
	    MemBuf sign_mb;
	    err->page_id = ERR_SQUID_SIGNATURE;
	    sign_mb = errorBuildContent(err);
	    memBufPrintf(&mb, "%s", sign_mb.buf);
	    memBufClean(&sign_mb);
	    err->page_id = saved_id;
	    do_quote = 0;
	} else {
	    /* wow, somebody put %S into ERR_SIGNATURE, stop recursion */
	    p = "[%S]";
	}
	break;
    case 't':
	memBufPrintf(&mb, "%s", mkhttpdlogtime(&squid_curtime));
	break;
    case 'T':
	memBufPrintf(&mb, "%s", mkrfc1123(squid_curtime));
	break;
    case 'U':
	p = r ? urlCanonicalClean(r) : err->url ? err->url : "[no URL]";
	break;
    case 'u':
	p = r ? urlCanonical(r) : err->url ? err->url : "[no URL]";
	break;
    case 'w':
	if (Config.adminEmail)
	    memBufPrintf(&mb, "%s", Config.adminEmail);
	else
	    p = "[unknown]";
	break;
    case 'z':
	if (err->dnsserver_msg)
	    p = err->dnsserver_msg;
	else
	    p = "[unknown]";
	break;
    case '%':
	p = "%";
	break;
    default:
	memBufPrintf(&mb, "%%%c", token);
	do_quote = 0;
	break;
    }
    if (!p)
	p = mb.buf;		/* do not use mb after this assignment! */
    assert(p);
    debug(4, 3) ("errorConvert: %%%c --> '%s'\n", token, p);
    if (do_quote)
	p = html_quote(p);
    return p;
}

/* allocates and initializes an error response */
HttpReply *
errorBuildReply(ErrorState * err)
{
    HttpReply *rep = httpReplyCreate();
    const char *name = errorPageName(err->page_id);
    http_version_t version;
    /* no LMT for error pages; error pages expire immediately */
    httpBuildVersion(&version, 1, 0);
    if (strchr(name, ':')) {
	/* Redirection */
	httpReplySetHeaders(rep, version, HTTP_MOVED_TEMPORARILY, NULL, "text/html", 0, 0, squid_curtime);
	if (err->request) {
	    char *quoted_url = rfc1738_escape_part(urlCanonical(err->request));
	    httpHeaderPutStrf(&rep->header, HDR_LOCATION, name, quoted_url);
	}
	httpHeaderPutStrf(&rep->header, HDR_X_SQUID_ERROR, "%d %s\n", err->http_status, "Access Denied");
    } else {
	MemBuf content = errorBuildContent(err);
	httpReplySetHeaders(rep, version, err->http_status, NULL, "text/html", content.size, 0, squid_curtime);
	/*
	 * include some information for downstream caches. Implicit
	 * replaceable content. This isn't quite sufficient. xerrno is not
	 * necessarily meaningful to another system, so we really should
	 * expand it. Additionally, we should identify ourselves. Someone
	 * might want to know. Someone _will_ want to know OTOH, the first
	 * X-CACHE-MISS entry should tell us who.
	 */
	httpHeaderPutStrf(&rep->header, HDR_X_SQUID_ERROR, "%s %d",
	    name, err->xerrno);
	httpBodySet(&rep->body, &content);
	/* do not memBufClean() the content, it was absorbed by httpBody */
    }
    return rep;
}

static MemBuf
errorBuildContent(ErrorState * err)
{
    MemBuf content;
    const char *m;
    const char *p;
    const char *t;
    assert(err != NULL);
    assert(err->page_id > ERR_NONE && err->page_id < error_page_count);
    memBufDefInit(&content);
    m = error_text[err->page_id];
    assert(m);
    while ((p = strchr(m, '%'))) {
	memBufAppend(&content, m, p - m);	/* copy */
	t = errorConvert(*++p, err);	/* convert */
	memBufPrintf(&content, "%s", t);	/* copy */
	m = p + 1;		/* advance */
    }
    if (*m)
	memBufPrintf(&content, "%s", m);	/* copy tail */
    assert(content.size == strlen(content.buf));
    return content;
}