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/*
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS HEADER.
 *
 * Copyright 2008 Sun Microsystems, Inc. All rights reserved.
 *
 * THE BSD LICENSE
 *
 * Redistribution and use in source and binary forms, with or without 
 * modification, are permitted provided that the following conditions are met:
 *
 * Redistributions of source code must retain the above copyright notice, this
 * list of conditions and the following disclaimer. 
 * 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. 
 *
 * Neither the name of the  nor the names of its contributors may be
 * used to endorse or promote products derived from this software without 
 * specific prior written permission. 
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "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 COPYRIGHT OWNER 
 * OR CONTRIBUTORS 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.
 */

#include <stdio.h>
#include <stdlib.h>

#include "http.h"
#include "protocol.h"

#include "../util/pblock.h"
#include "../util/pool.h"
#include "../util/util.h"


static int http_etag = 1;

/* --------------------------- http_format_etag --------------------------- */

NSAPI_PUBLIC void http_format_etag(Session *sn, Request *rq, char *etagp, int etaglen, off_t size, time_t mtime)
{
    /*
     * Heuristic for weak/strong validator: if the request was made within
     * a second of the last-modified date, then we send a weak Etag.
     */
    if (rq->req_start - mtime <= 1) {
        /* Send a weak Etag */
        *etagp++ = 'W';
        *etagp++ = '/';
        etaglen -= 2;
    }

    /*
     * Create an Etag out of the metadata (size, mtime) to obtain Etag
     * uniqueness.
     */
    util_snprintf(etagp, etaglen, "\"%x-%x\"", (int)size, (int)mtime);
}


/* --------------------------- http_weaken_etag --------------------------- */

NSAPI_PUBLIC void http_weaken_etag(Session *sn, Request *rq)
{
    /* Replace any existing strong Etag with a weak Etag */
    pb_param *pp = pblock_findkey(pb_key_etag, rq->srvhdrs);
    if (pp) {
        if (pp->value[0] != 'W' || pp->value[1] != '/') {
            char *weak = (char *) pool_malloc(sn->pool, 2 + strlen(pp->value) + 1);

            weak[0] = 'W';
            weak[1] = '/';
            strcpy(weak + 2, pp->value);

            pool_free(sn->pool, pp->value);
            pp->value = weak;
        }
    }
}


/* ------------------------------ match_etag ------------------------------ */

NSAPI_PUBLIC int http_match_etag(const char *header, const char *etag, int strong)
{
    if (!etag)
        return 0; /* mismatch */

    if (header[0] == '*')
        return 1; /* match */

    if (etag[0] == 'W' && etag[1] == '/') {
        /* Weak Etags never match when using the strong validator */
        if (strong)
            return 0; /* mismatch */

        etag += 2;
    }

    /* Look for Etag in header */
    const char *found = strstr(header, etag);
    if (!found)
        return 0; /* mismatch */

    /* Weak Etags never match when using the strong validator */
    if (strong && found >= header + 2 && found[-2] == 'W' && found[-1] == '/')
        return 0; /* mismatch */

    return 1; /* match */
}


/* ----------------------- http_check_preconditions ----------------------- */

NSAPI_PUBLIC int http_check_preconditions(Session *sn, Request *rq, struct tm *mtm, const char *etag)
{
    char *header;

    /* If-modified-since */
    header = pblock_findkeyval(pb_key_if_modified_since, rq->headers);
    if (header) {
        if (mtm && util_later_than(mtm, header)) {
            protocol_status(sn, rq, PROTOCOL_NOT_MODIFIED, NULL);
            return REQ_ABORTED;
        }
    }

    /* If-unmodified-since */
    header = pblock_findkeyval(pb_key_if_unmodified_since, rq->headers);
    if (header) {
        if (mtm && !util_later_than(mtm, header)) {
            if(util_isdate(header)) {
                protocol_status(sn, rq, PROTOCOL_PRECONDITION_FAIL, NULL);
                return REQ_ABORTED;
            }
        }
    }

    /* If-none-match */
    header = pblock_findkeyval(pb_key_if_none_match, rq->headers);
    if (header) {
        /* If the If-none-match header matches the current Etag... */
        if (ISMGET(rq) || ISMHEAD(rq)) {
            if (http_match_etag(header, etag, PR_FALSE)) {
                protocol_status(sn, rq, PROTOCOL_NOT_MODIFIED, NULL);
                return REQ_ABORTED;
            }
        } else {
            if (http_match_etag(header, etag, PR_TRUE)) {
                protocol_status(sn, rq, PROTOCOL_PRECONDITION_FAIL, NULL);
                return REQ_ABORTED;
            }
        }
    }

    /* If-match */
    header = pblock_findkeyval(pb_key_if_match, rq->headers);
    if (header) {
        /* If the If-match header matches the current Etag... */
        if (!http_match_etag(header, etag, PR_TRUE)) {
            protocol_status(sn, rq, PROTOCOL_PRECONDITION_FAIL, NULL);
            return REQ_ABORTED;
        }
    }
    
    /* If-range */
    header = pblock_findkeyval(pb_key_if_range, rq->headers);
    char *range = pblock_findkeyval(pb_key_range, rq->headers);
    if (range && header) {
        int rmir = PR_FALSE;
        if (util_isdate(header)) {
            if (mtm && !util_later_than(mtm, header)) {
                rmir = PR_TRUE;
            }
        } else {
            if (!http_match_etag(header, etag, PR_TRUE)) {
                rmir = PR_TRUE;
            }
        }
        
        if(rmir) {
            pblock_removekey(pb_key_range, rq->headers);
        }
    }

    return REQ_PROCEED;
}


/* ---------------------------- http_set_finfo ---------------------------- */

static inline int set_finfo(Session *sn, Request *rq, off_t size, time_t mtime)
{
    struct tm mtms;
    struct tm *mtm = system_gmtime(&mtime, &mtms);
    pb_param *pp;

    /* Insert Last-modified */
    if (mtm) {
        pp = pblock_key_param_create(rq->srvhdrs, pb_key_last_modified, NULL,
                                     HTTP_DATE_LEN);
        if (!pp || !pp->value)
            return REQ_ABORTED;
        strftime(pp->value, HTTP_DATE_LEN, HTTP_DATE_FMT, mtm);
        pblock_kpinsert(pb_key_last_modified, pp, rq->srvhdrs);
    }

    /* Insert Content-length */
    const int content_length_size = 21;
    pp = pblock_key_param_create(rq->srvhdrs, pb_key_content_length, NULL,
                                 content_length_size);
    if (!pp || !pp->value)
        return REQ_ABORTED;
    snprintf(pp->value, content_length_size, "%lld", (long long)size);
    pblock_kpinsert(pb_key_content_length, pp, rq->srvhdrs);

    char *etag;
    if (http_etag) {
        /* Insert Etag */
        pp = pblock_key_param_create(rq->srvhdrs, pb_key_etag, NULL, MAX_ETAG);
        if (!pp || !pp->value)
            return REQ_ABORTED;
        http_format_etag(sn, rq, pp->value, MAX_ETAG, size, mtime);
        pblock_kpinsert(pb_key_etag, pp, rq->srvhdrs);
        etag = pp->value;
    } else {
        etag = NULL;
    }

    /* Check If-modified-since, etc. */
    return http_check_preconditions(sn, rq, mtm, etag);
}

NSAPI_PUBLIC int http_set_finfo(Session *sn, Request *rq, struct stat *finfo)
{
    return set_finfo(sn, rq, finfo->st_size, finfo->st_mtime);
}