mod_jsonp.c

/*
 * Copyright (c) Moriyoshi Koizumi
 * 
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 * 
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 * 
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
 * THE SOFTWARE.
 */

#include <httpd.h>
#include <http_config.h>
#include <http_core.h>
#include <http_log.h>
#include <http_main.h>
#include <http_protocol.h>
#include <http_request.h>
#include <util_script.h>
#include <http_connection.h>

#include "apr_strings.h"

#define JSON_MIME_TYPE "application/json"
#define JAVASCRIPT_MIME_TYPE "text/javascript"

module AP_MODULE_DECLARE_DATA jsonp_module;

typedef struct jsonp_req_ctx {
    apr_table_t *query;
} jsonp_req_ctx_t;

static apr_table_t *parse_query(apr_pool_t *pool, const char* query)
{
    apr_table_t *retval = apr_table_make(pool, 0);
    const char *p = query;
    while (*p) {
        const char *n = strchr(p, '&'), *_n = n ? n: p + strlen(p);
        char *chunk = apr_pstrndup(pool, p, _n - p); 
        char *s = strchr(chunk, '=');
        if (s) {
            *s = '\0';
            ap_unescape_url(chunk);
            ap_unescape_url(s + 1);
            apr_table_setn(retval, chunk, s + 1);
        } else {
            ap_unescape_url(chunk);
            apr_table_setn(retval, chunk, "");
        }
        if (!n)
            p = _n;
        else
            p = n + 1;
    }
    return retval;
}

static apr_status_t jsonp_filter(ap_filter_t *f, apr_bucket_brigade *bb)
{
    const char *callback = f->ctx;
    apr_size_t l = strlen(f->r->content_type);
    if (!f->r->content_type || l < sizeof(JSON_MIME_TYPE) - 1 ||
            strncmp(f->r->content_type, JSON_MIME_TYPE,
                    sizeof(JSON_MIME_TYPE) - 1) != 0) {
        return ap_pass_brigade(f->next, bb);
    } else {
        apr_bucket_brigade *_bb = apr_brigade_create(f->r->pool, f->c->bucket_alloc); 
        apr_bucket *b;

        APR_BRIGADE_INSERT_TAIL(_bb, apr_bucket_pool_create(callback, strlen(callback), f->r->pool, bb->bucket_alloc));
        APR_BRIGADE_INSERT_TAIL(_bb, apr_bucket_immortal_create("(", 1, bb->bucket_alloc));
        while ((b = APR_BRIGADE_FIRST(bb)) &&  b != APR_BRIGADE_SENTINEL(bb)) {
            if (APR_BUCKET_IS_EOS(b)) {
                APR_BRIGADE_INSERT_TAIL(_bb, apr_bucket_immortal_create(")", 1, bb->bucket_alloc));
            }
            APR_BUCKET_REMOVE(b);
            APR_BRIGADE_INSERT_TAIL(_bb, b);
        }

        f->r->content_type = apr_pstrcat(f->r->pool, JAVASCRIPT_MIME_TYPE, f->r->content_type + sizeof(JSON_MIME_TYPE) - 1, NULL);
        return ap_pass_brigade(f->next, _bb);
    }
}

static int jsonp_req_init(request_rec *r)
{
    jsonp_req_ctx_t *ctx = apr_palloc(r->pool, sizeof(jsonp_req_ctx_t));
    ctx->query = NULL;
    if (r->parsed_uri.query)
        ctx->query = parse_query(r->pool, r->parsed_uri.query);
    ap_set_module_config(r->request_config, &jsonp_module, ctx);

    return OK;
}

static void jsonp_insert_filter(request_rec *r)
{
    jsonp_req_ctx_t *ctx = ap_get_module_config(r->request_config, &jsonp_module);
    const char *callback = ctx->query ? apr_table_get(ctx->query, "callback"): NULL;
    if (callback) {
        ap_add_output_filter("jsonp", (void*)callback, r, r->connection);
    }
}

static void jsonp_register_hooks(apr_pool_t *p)
{
    ap_hook_fixups(jsonp_req_init, NULL, NULL, APR_HOOK_MIDDLE);
    ap_hook_insert_filter(jsonp_insert_filter, NULL, NULL, APR_HOOK_MIDDLE);
    ap_register_output_filter("jsonp", jsonp_filter, NULL, AP_FTYPE_RESOURCE);
}

module AP_MODULE_DECLARE_DATA jsonp_module =
{
    STANDARD20_MODULE_STUFF,
    NULL,                   /* per-directory config creator */
    NULL,                   /* dir config merger */
    NULL,                   /* server config creator */
    NULL,                   /* server config merger */
    NULL,                   /* command table */
    jsonp_register_hooks,   /* set up other request processing hooks */
};

/*
 * vim: sts=4 sw=4 ts=4 et
 */