mod_rewrite.c

Apache官方在今天放出产品系列2.2的最新版本2.2.11的源码包 最流行的HTTP服务器软件之一

    return value;
}

static char *lookup_map_program(request_rec *r, apr_file_t *fpin,
                                apr_file_t *fpout, char *key)
{
    char *buf;
    char c;
    apr_size_t i, nbytes, combined_len = 0;
    apr_status_t rv;
    const char *eol = APR_EOL_STR;
    apr_size_t eolc = 0;
    int found_nl = 0;
    result_list *buflist = NULL, *curbuf = NULL;

#ifndef NO_WRITEV
    struct iovec iova[2];
    apr_size_t niov;
#endif

    /* when `RewriteEngine off' was used in the per-server
     * context then the rewritemap-programs were not spawned.
     * In this case using such a map (usually in per-dir context)
     * is useless because it is not available.
     *
     * newlines in the key leave bytes in the pipe and cause
     * bad things to happen (next map lookup will use the chars
     * after the \n instead of the new key etc etc - in other words,
     * the Rewritemap falls out of sync with the requests).
     */
    if (fpin == NULL || fpout == NULL || ap_strchr(key, '\n')) {
        return NULL;
    }

    /* take the lock */
    if (rewrite_mapr_lock_acquire) {
        rv = apr_global_mutex_lock(rewrite_mapr_lock_acquire);
        if (rv != APR_SUCCESS) {
            ap_log_rerror(APLOG_MARK, APLOG_ERR, rv, r,
                          "apr_global_mutex_lock(rewrite_mapr_lock_acquire) "
                          "failed");
            return NULL; /* Maybe this should be fatal? */
        }
    }

    /* write out the request key */
#ifdef NO_WRITEV
    nbytes = strlen(key);
    apr_file_write(fpin, key, &nbytes);
    nbytes = 1;
    apr_file_write(fpin, "\n", &nbytes);
#else
    iova[0].iov_base = key;
    iova[0].iov_len = strlen(key);
    iova[1].iov_base = "\n";
    iova[1].iov_len = 1;

    niov = 2;
    apr_file_writev(fpin, iova, niov, &nbytes);
#endif

    buf = apr_palloc(r->pool, REWRITE_PRG_MAP_BUF + 1);

    /* read in the response value */
    nbytes = 1;
    apr_file_read(fpout, &c, &nbytes);
    do {
        i = 0;
        while (nbytes == 1 && (i < REWRITE_PRG_MAP_BUF)) {
            if (c == eol[eolc]) {
                if (!eol[++eolc]) {
                    /* remove eol from the buffer */
                    --eolc;
                    if (i < eolc) {
                        curbuf->len -= eolc-i;
                        i = 0;
                    }
                    else {
                        i -= eolc;
                    }
                    ++found_nl;
                    break;
                }
            }

            /* only partial (invalid) eol sequence -> reset the counter */
            else if (eolc) {
                eolc = 0;
            }

            /* catch binary mode, e.g. on Win32 */
            else if (c == '\n') {
                ++found_nl;
                break;
            }

            buf[i++] = c;
            apr_file_read(fpout, &c, &nbytes);
        }

        /* well, if there wasn't a newline yet, we need to read further */
        if (buflist || (nbytes == 1 && !found_nl)) {
            if (!buflist) {
                curbuf = buflist = apr_palloc(r->pool, sizeof(*buflist));
            }
            else if (i) {
                curbuf->next = apr_palloc(r->pool, sizeof(*buflist));
                curbuf = curbuf->next;

            }
            curbuf->next = NULL;

            if (i) {
                curbuf->string = buf;
                curbuf->len = i;
                combined_len += i;
                buf = apr_palloc(r->pool, REWRITE_PRG_MAP_BUF);
            }

            if (nbytes == 1 && !found_nl) {
                i = 0;
                continue;
            }
        }

        break;
    } while (1);

    /* concat the stuff */
    if (buflist) {
        char *p;

        p = buf = apr_palloc(r->pool, combined_len + 1); /* \0 */
        while (buflist) {
            if (buflist->len) {
                memcpy(p, buflist->string, buflist->len);
                p += buflist->len;
            }
            buflist = buflist->next;
        }
        *p = '\0';
        i = combined_len;
    }
    else {
        buf[i] = '\0';
    }

    /* give the lock back */
    if (rewrite_mapr_lock_acquire) {
        rv = apr_global_mutex_unlock(rewrite_mapr_lock_acquire);
        if (rv != APR_SUCCESS) {
            ap_log_rerror(APLOG_MARK, APLOG_ERR, rv, r,
                          "apr_global_mutex_unlock(rewrite_mapr_lock_acquire) "
                          "failed");
            return NULL; /* Maybe this should be fatal? */
        }
    }

    /* catch the "failed" case */
    if (i == 4 && !strcasecmp(buf, "NULL")) {
        return NULL;
    }

    return buf;
}

/*
 * generic map lookup
 */
static char *lookup_map(request_rec *r, char *name, char *key)
{
    rewrite_server_conf *conf;
    rewritemap_entry *s;
    char *value;
    apr_finfo_t st;
    apr_status_t rv;

    /* get map configuration */
    conf = ap_get_module_config(r->server->module_config, &rewrite_module);
    s = apr_hash_get(conf->rewritemaps, name, APR_HASH_KEY_STRING);

    /* map doesn't exist */
    if (!s) {
        return NULL;
    }

    switch (s->type) {
    /*
     * Text file map (perhaps random)
     */
    case MAPTYPE_RND:
    case MAPTYPE_TXT:
        rv = apr_stat(&st, s->checkfile, APR_FINFO_MIN, r->pool);
        if (rv != APR_SUCCESS) {
            ap_log_rerror(APLOG_MARK, APLOG_ERR, rv, r,
                          "mod_rewrite: can't access text RewriteMap file %s",
                          s->checkfile);
            rewritelog((r, 1, NULL,
                        "can't open RewriteMap file, see error log"));
            return NULL;
        }

        value = get_cache_value(s->cachename, st.mtime, key, r->pool);
        if (!value) {
            rewritelog((r, 6, NULL,
                        "cache lookup FAILED, forcing new map lookup"));

            value = lookup_map_txtfile(r, s->datafile, key);
            if (!value) {
                rewritelog((r, 5, NULL, "map lookup FAILED: map=%s[txt] key=%s",
                            name, key));
                set_cache_value(s->cachename, st.mtime, key, "");
                return NULL;
            }

            rewritelog((r, 5, NULL,"map lookup OK: map=%s[txt] key=%s -> val=%s",
                        name, key, value));
            set_cache_value(s->cachename, st.mtime, key, value);
        }
        else {
            rewritelog((r,5,NULL,"cache lookup OK: map=%s[txt] key=%s -> val=%s",
                        name, key, value));
        }

        if (s->type == MAPTYPE_RND && *value) {
            value = select_random_value_part(r, value);
            rewritelog((r, 5, NULL, "randomly chosen the subvalue `%s'",value));
        }

        return *value ? value : NULL;

    /*
     * DBM file map
     */
    case MAPTYPE_DBM:
        rv = apr_stat(&st, s->checkfile, APR_FINFO_MIN, r->pool);
        if (rv != APR_SUCCESS) {
            ap_log_rerror(APLOG_MARK, APLOG_ERR, rv, r,
                          "mod_rewrite: can't access DBM RewriteMap file %s",
                          s->checkfile);
        }
        else if(s->checkfile2 != NULL) {
            apr_finfo_t st2;

            rv = apr_stat(&st2, s->checkfile2, APR_FINFO_MIN, r->pool);
            if (rv != APR_SUCCESS) {
                ap_log_rerror(APLOG_MARK, APLOG_ERR, rv, r,
                              "mod_rewrite: can't access DBM RewriteMap "
                              "file %s", s->checkfile2);
            }
            else if(st2.mtime > st.mtime) {
                st.mtime = st2.mtime;
            }
        }
        if(rv != APR_SUCCESS) {
            rewritelog((r, 1, NULL,
                        "can't open DBM RewriteMap file, see error log"));
            return NULL;
        }

        value = get_cache_value(s->cachename, st.mtime, key, r->pool);
        if (!value) {
            rewritelog((r, 6, NULL,
                        "cache lookup FAILED, forcing new map lookup"));

            value = lookup_map_dbmfile(r, s->datafile, s->dbmtype, key);
            if (!value) {
                rewritelog((r, 5, NULL, "map lookup FAILED: map=%s[dbm] key=%s",
                            name, key));
                set_cache_value(s->cachename, st.mtime, key, "");
                return NULL;
            }

            rewritelog((r, 5, NULL, "map lookup OK: map=%s[dbm] key=%s -> "
                        "val=%s", name, key, value));

            set_cache_value(s->cachename, st.mtime, key, value);
            return value;
        }

        rewritelog((r, 5, NULL, "cache lookup OK: map=%s[dbm] key=%s -> val=%s",
                    name, key, value));
        return *value ? value : NULL;

    /*
     * Program file map
     */
    case MAPTYPE_PRG:
        value = lookup_map_program(r, s->fpin, s->fpout, key);
        if (!value) {
            rewritelog((r, 5,NULL,"map lookup FAILED: map=%s key=%s", name,
                        key));
            return NULL;
        }

        rewritelog((r, 5, NULL, "map lookup OK: map=%s key=%s -> val=%s",
                    name, key, value));
        return value;

    /*
     * Internal Map
     */
    case MAPTYPE_INT:
        value = s->func(r, key);
        if (!value) {
            rewritelog((r, 5,NULL,"map lookup FAILED: map=%s key=%s", name,
                        key));
            return NULL;
        }

        rewritelog((r, 5, NULL, "map lookup OK: map=%s key=%s -> val=%s",
                    name, key, value));
        return value;
    }

    return NULL;
}

/*
 * lookup a HTTP header and set VARY note
 */
static const char *lookup_header(const char *name, rewrite_ctx *ctx)
{
    const char *val = apr_table_get(ctx->r->headers_in, name);

    if (val) {
        ctx->vary_this = ctx->vary_this
                         ? apr_pstrcat(ctx->r->pool, ctx->vary_this, ", ",
                                       name, NULL)
                         : apr_pstrdup(ctx->r->pool, name);
    }

    return val;
}

/*
 * lookahead helper function
 * Determine the correct URI path in perdir context
 */
static APR_INLINE const char *la_u(rewrite_ctx *ctx)
{
    rewrite_perdir_conf *conf;

    if (*ctx->uri == '/') {
        return ctx->uri;
    }

    conf = ap_get_module_config(ctx->r->per_dir_config, &rewrite_module);

    return apr_pstrcat(ctx->r->pool, conf->baseurl
                                     ? conf->baseurl : conf->directory,
                       ctx->uri, NULL);
}

/*
 * generic variable lookup
 */
static char *lookup_variable(char *var, rewrite_ctx *ctx)
{
    const char *result;
    request_rec *r = ctx->r;
    apr_size_t varlen = strlen(var);

    /* fast exit */
    if (varlen < 4) {
        return apr_pstrdup(r->pool, "");
    }

    result = NULL;

    /* fast tests for variable length variables (sic) first */
    if (var[3] == ':') {
        if (var[4] && !strncasecmp(var, "ENV", 3)) {
            var += 4;
            result = apr_table_get(r->notes, var);

            if (!result) {
                result = apr_table_get(r->subprocess_env, var);
            }
            if (!result) {
                result = getenv(var);
            }
        }
        else if (var[4] && !strncasecmp(var, "SSL", 3) && rewrite_ssl_lookup) {
            result = rewrite_ssl_lookup(r->pool, r->server, r->connection, r,
                                        var + 4);
        }
    }
    else if (var[4] == ':') {
        if (var[5]) {
            request_rec *rr;
            const char *path;

            if (!strncasecmp(var, "HTTP", 4)) {
                result = lookup_header(var+5, ctx);
            }
            else if (!strncasecmp(var, "LA-U", 4)) {
                if (ctx->uri && subreq_ok(r)) {
                    path = ctx->perdir ? la_u(ctx) : ctx->uri;
                    rr = ap_sub_req_lookup_uri(path, r, NULL);
                    ctx->r = rr;
                    result = apr_pstrdup(r->pool, lookup_variable(var+5, ctx));
                    ctx->r = r;
                    ap_destroy_sub_req(rr);

                    rewritelog((r, 5, ctx->perdir, "lookahead: path=%s var=%s "
                                "-> val=%s", path, var+5, result));

                    return (char *)result;
                }
            }
            else if (!strncasecmp(var, "LA-F", 4)) {
                if (ctx->uri && subreq_ok(r)) {
                    path = ctx->uri;
                    if (ctx->perdir && *path == '/') {
                        /* sigh, the user wants a file based subrequest, but
                         * we can't do one, since we don't know what the file
                         * path is! In this case behave like LA-U.
                         */
                        rr = ap_sub_req_lookup_uri(path, r, NULL);
                    }
                    else {
                        if (ctx->perdir) {
                            rewrite_perdir_conf *conf;

                            conf = ap_get_module_config(r->per_dir_config,
                                                        &rewrite_module);

                            path = apr_pstrcat(r->pool, conf->directory, path,
                                               NULL);
                        }

                        rr = ap_sub_req_lookup_file(path, r, NULL);
                    }

                    ctx->r = rr;
                    result = apr_pstrdup(r->pool, lookup_variable(var+5, ctx));