resource.c

Go to the documentation of this file.

/*
 * Copyright 2011 Vincent Sanders <vince@netsurf-browser.org>
 *
 * This file is part of NetSurf.
 *
 * NetSurf 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; version 2 of the License.
 *
 * NetSurf 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, see <http://www.gnu.org/licenses/>.
 */
 
/**
 * \file
 * resource scheme URL handling. Based on the data fetcher by Rob Kendrick
 */
 
#include <stdlib.h>
#include <stdbool.h>
#include <string.h>
#include <strings.h>
#include <stdio.h>
#include <stdarg.h>
#include <libwapcaplet/libwapcaplet.h>
 
#include "netsurf/inttypes.h"
#include "utils/nsurl.h"
#include "utils/corestrings.h"
#include "utils/log.h"
#include "utils/time.h"
#include "utils/messages.h"
#include "utils/utils.h"
#include "utils/ring.h"
#include "netsurf/fetch.h"
#include "desktop/gui_internal.h"
 
#include "content/fetch.h"
#include "content/fetchers.h"
#include "content/fetchers/resource.h"
 
#define DIRECT_ETAG_VALUE 123456
 
/** Valid resource paths */
static const char *fetch_resource_paths[] = {
        "adblock.css",
        "default.css",
        "internal.css",
        "quirks.css",
        "user.css",
        "credits.html",
        "licence.html",
        "welcome.html",
        "favicon.ico",
        "default.ico",
        "netsurf.png",
        "icons/arrow-l.png",
        "icons/content.png",
        "icons/directory.png",
        "icons/directory2.png",
        "icons/hotlist-add.png",
        "icons/hotlist-rmv.png",
        "icons/search.png"
};
 
/**
 * map of resource scheme paths to redirect urls
 */
static struct fetch_resource_map_entry {
        lwc_string *path; /**< resource scheme path */
        nsurl *redirect_url; /**< url to redirect to */
        const uint8_t *data; /**< direct pointer to data */
        size_t data_len; /**< length of direct data */
} fetch_resource_map[NOF_ELEMENTS(fetch_resource_paths)];
 
struct fetch_resource_context;
 
typedef bool (*fetch_resource_handler)(struct fetch_resource_context *);
 
/** Context for an resource fetch */
struct fetch_resource_context {
        struct fetch_resource_context *r_next, *r_prev;
 
        struct fetch *fetchh; /**< Handle for this fetch */
 
        bool aborted; /**< Flag indicating fetch has been aborted */
        bool locked; /**< Flag indicating entry is already entered */
 
        nsurl *url; /**< requested url */
 
        struct fetch_resource_map_entry *entry; /**< resource map entry */
 
        fetch_resource_handler handler;
 
        time_t etag;
};
 
static struct fetch_resource_context *ring = NULL;
 
static uint32_t fetch_resource_path_count;
 
/** issue fetch callbacks with locking */
static inline bool fetch_resource_send_callback(const fetch_msg *msg,
                struct fetch_resource_context *ctx)
{
        ctx->locked = true;
        fetch_send_callback(msg, ctx->fetchh);
        ctx->locked = false;
 
        return ctx->aborted;
}
 
static bool fetch_resource_send_header(struct fetch_resource_context *ctx,
                const char *fmt, ...)
{
        fetch_msg msg;
        char header[64];
        va_list ap;
        int len;
 
        va_start(ap, fmt);
        len = vsnprintf(header, sizeof header, fmt, ap);
        va_end(ap);
 
        if (len >= (int)sizeof(header) || len < 0) {
                return false;
        }
 
        msg.type = FETCH_HEADER;
        msg.data.header_or_data.buf = (const uint8_t *) header;
        msg.data.header_or_data.len = len;
 
        return fetch_resource_send_callback(&msg, ctx);
}
 
 
 
/**
 * resource handler that results in a redirect to another url.
 */
static bool fetch_resource_redirect_handler(struct fetch_resource_context *ctx)
{
        fetch_msg msg;
 
        /* content is going to return redirect */
        fetch_set_http_code(ctx->fetchh, 302);
 
        msg.type = FETCH_REDIRECT;
        msg.data.redirect = nsurl_access(ctx->entry->redirect_url);
        fetch_resource_send_callback(&msg, ctx);
 
        return true;
}
 
/* resource handler that returns data directly */
static bool fetch_resource_data_handler(struct fetch_resource_context *ctx)
{
        fetch_msg msg;
 
        /* Check if we can just return not modified */
        if (ctx->etag != 0 && ctx->etag == DIRECT_ETAG_VALUE) {
                fetch_set_http_code(ctx->fetchh, 304);
                msg.type = FETCH_NOTMODIFIED;
                fetch_resource_send_callback(&msg, ctx);
                return true;
        }
 
        /* fetch is going to be successful */
        fetch_set_http_code(ctx->fetchh, 200);
 
        /* Any callback can result in the fetch being aborted.
         * Therefore, we _must_ check for this after _every_ call to
         * fetch_file_send_callback().
         */
 
        /* content type */
        if (fetch_resource_send_header(ctx, "Content-Type: %s",
                                       guit->fetch->filetype(lwc_string_data(ctx->entry->path)))) {
                goto fetch_resource_data_aborted;
        }
 
        /* content length */
        if (fetch_resource_send_header(ctx, "Content-Length: %" PRIsizet,
                                       ctx->entry->data_len)) {
                goto fetch_resource_data_aborted;
        }
 
        /* create etag */
        if (fetch_resource_send_header(ctx, "ETag: \"%10" PRId64 "\"",
                                       (int64_t) DIRECT_ETAG_VALUE)) {
                goto fetch_resource_data_aborted;
        }
 
        /* create max-age of 1 year */
        if (fetch_resource_send_header(ctx,
                        "Cache-Control: max-age=31536000")) {
                goto fetch_resource_data_aborted;
        }
 
        msg.type = FETCH_DATA;
        msg.data.header_or_data.buf = (const uint8_t *) ctx->entry->data;
        msg.data.header_or_data.len = ctx->entry->data_len;
        fetch_resource_send_callback(&msg, ctx);
 
        if (ctx->aborted == false) {
                msg.type = FETCH_FINISHED;
                fetch_resource_send_callback(&msg, ctx);
        }
 
fetch_resource_data_aborted:
 
        return true;
}
 
static bool fetch_resource_notfound_handler(struct fetch_resource_context *ctx)
{
        fetch_msg msg;
        int code = 404;
        char buffer[1024];
        const char *title;
        char key[8];
 
        /* content is going to return error code */
        fetch_set_http_code(ctx->fetchh, code);
 
        /* content type */
        if (fetch_resource_send_header(ctx, "Content-Type: text/html"))
                goto fetch_resource_notfound_handler_aborted;
 
        snprintf(key, sizeof key, "HTTP%03d", code);
        title = messages_get(key);
 
        snprintf(buffer, sizeof buffer, "<html><head><title>%s</title></head>"
                        "<body><h1>%s</h1>"
                        "<p>Error %d while fetching file %s</p></body></html>",
                        title, title, code, nsurl_access(ctx->url));
 
        msg.type = FETCH_DATA;
        msg.data.header_or_data.buf = (const uint8_t *) buffer;
        msg.data.header_or_data.len = strlen(buffer);
        if (fetch_resource_send_callback(&msg, ctx))
                goto fetch_resource_notfound_handler_aborted;
 
        msg.type = FETCH_FINISHED;
        fetch_resource_send_callback(&msg, ctx);
 
fetch_resource_notfound_handler_aborted:
        return false;
}
 
 
 
/** callback to initialise the resource fetcher. */
static bool fetch_resource_initialise(lwc_string *scheme)
{
        struct fetch_resource_map_entry *e;
        uint32_t i;
        nserror res;
 
        fetch_resource_path_count = 0;
 
        for (i = 0; i < NOF_ELEMENTS(fetch_resource_paths); i++) {
                e = &fetch_resource_map[fetch_resource_path_count];
 
                if (lwc_intern_string(fetch_resource_paths[i],
                                strlen(fetch_resource_paths[i]),
                                &e->path) != lwc_error_ok) {
                        while (i > 0) {
                                i--;
                                lwc_string_unref(fetch_resource_map[i].path);
                                nsurl_unref(fetch_resource_map[i].redirect_url);
                        }
                        /** \todo should this exit with an error condition? */
                }
 
                e->data = NULL;
                res = guit->fetch->get_resource_data(lwc_string_data(e->path),
                                                     &e->data,
                                                     &e->data_len);
                if (res == NSERROR_OK) {
                        NSLOG(netsurf, INFO, "direct data for %s",
                              fetch_resource_paths[i]);
                        fetch_resource_path_count++;
                } else {
                        e->redirect_url = guit->fetch->get_resource_url(fetch_resource_paths[i]);
                        if (e->redirect_url == NULL) {
                                lwc_string_unref(e->path);
                        } else {
                                NSLOG(netsurf, INFO, "redirect url for %s",
                                      fetch_resource_paths[i]);
                                fetch_resource_path_count++;
                        }
                }
        }
 
        return true;
}
 
/** callback to finalise the resource fetcher. */
static void fetch_resource_finalise(lwc_string *scheme)
{
        uint32_t i;
 
        for (i = 0; i < fetch_resource_path_count; i++) {
                lwc_string_unref(fetch_resource_map[i].path);
                if (fetch_resource_map[i].data != NULL) {
                        guit->fetch->release_resource_data(fetch_resource_map[i].data);
                } else {
                        nsurl_unref(fetch_resource_map[i].redirect_url);
                }
        }
}
 
static bool fetch_resource_can_fetch(const nsurl *url)
{
        return true;
}
 
/**
 * set up a resource fetch context.
 */
static void *
fetch_resource_setup(struct fetch *fetchh,
                     nsurl *url,
                     bool only_2xx,
                     bool downgrade_tls,
                     const char *post_urlenc,
                     const struct fetch_multipart_data *post_multipart,
                     const char **headers)
{
        struct fetch_resource_context *ctx;
        lwc_string *path;
        nserror ret;
        uint32_t i;
 
        ctx = calloc(1, sizeof(*ctx));
        if (ctx == NULL) {
                return NULL;
        }
 
        ctx->handler = fetch_resource_notfound_handler;
 
        if ((path = nsurl_get_component(url, NSURL_PATH)) != NULL) {
                bool match;
 
                /* Ensure requested path is valid */
                for (i = 0; i < fetch_resource_path_count; i++) {
                        if (lwc_string_isequal(path,
                                        fetch_resource_map[i].path,
                                        &match) == lwc_error_ok && match) {
                                /* found a url match, select handler */
                                ctx->entry = &fetch_resource_map[i];
                                if (ctx->entry->data != NULL) {
                                        ctx->handler = fetch_resource_data_handler;
                                } else {
                                        ctx->handler = fetch_resource_redirect_handler;
                                }
                                break;
                        }
                }
 
                lwc_string_unref(path);
        }
 
        ctx->url = nsurl_ref(url);
 
        /* Scan request headers looking for If-None-Match */
        for (i = 0; headers[i] != NULL; i++) {
                if (strncasecmp(headers[i], "If-None-Match:",
                                SLEN("If-None-Match:")) != 0) {
                        continue;
                }
 
                /* If-None-Match: "12345678" */
                const char *d = headers[i] + SLEN("If-None-Match:");
 
                /* Scan to first digit, if any */
                while (*d != '\0' && (*d < '0' || '9' < *d))
                        d++;
 
                /* Convert to time_t */
                if (*d != '\0') {
                        ret = nsc_snptimet(d, strlen(d), &ctx->etag);
                        if (ret != NSERROR_OK) {
                                NSLOG(fetch, WARNING,
                                                "Bad If-None-Match value");
                        }
                }
        }
 
        ctx->fetchh = fetchh;
 
        RING_INSERT(ring, ctx);
 
        return ctx;
}
 
/** callback to free a resource fetch */
static void fetch_resource_free(void *ctx)
{
        struct fetch_resource_context *c = ctx;
        if (c->url != NULL)
                nsurl_unref(c->url);
        free(ctx);
}
 
/** callback to start a resource fetch */
static bool fetch_resource_start(void *ctx)
{
        return true;
}
 
/** callback to abort a resource fetch */
static void fetch_resource_abort(void *ctx)
{
        struct fetch_resource_context *c = ctx;
 
        /* To avoid the poll loop having to deal with the fetch context
         * disappearing from under it, we simply flag the abort here.
         * The poll loop itself will perform the appropriate cleanup.
         */
        c->aborted = true;
}
 
 
/** callback to poll for additional resource fetch contents */
static void fetch_resource_poll(lwc_string *scheme)
{
        struct fetch_resource_context *c, *save_ring = NULL;
 
        while (ring != NULL) {
                /* Take the first entry from the ring */
                c = ring;
                RING_REMOVE(ring, c);
 
                /* Ignore fetches that have been flagged as locked.
                 * This allows safe re-entrant calls to this function.
                 * Re-entrancy can occur if, as a result of a callback,
                 * the interested party causes fetch_poll() to be called
                 * again.
                 */
                if (c->locked == true) {
                        RING_INSERT(save_ring, c);
                        continue;
                }
 
                /* Only process non-aborted fetches */
                if (c->aborted == false) {
                        /* resource fetches can be processed in one go */
                        c->handler(c);
                }
 
                /* And now finish */
                fetch_remove_from_queues(c->fetchh);
                fetch_free(c->fetchh);
        }
 
        /* Finally, if we saved any fetches which were locked, put them back
         * into the ring for next time
         */
        ring = save_ring;
}
 
nserror fetch_resource_register(void)
{
        lwc_string *scheme = lwc_string_ref(corestring_lwc_resource);
        const struct fetcher_operation_table fetcher_ops = {
                .initialise = fetch_resource_initialise,
                .acceptable = fetch_resource_can_fetch,
                .setup = fetch_resource_setup,
                .start = fetch_resource_start,
                .abort = fetch_resource_abort,
                .free = fetch_resource_free,
                .poll = fetch_resource_poll,
                .finalise = fetch_resource_finalise
        };
 
        return fetcher_add(scheme, &fetcher_ops);
}