Initialize some variables to remove warnings.

[xombrero.git] / tldlist.c

/*
 * Copyright (c) 2012 Elias Norberg <xyzzy@kudzu.se>
 *
 * Permission to use, copy, modify, and distribute this software for any
 * purpose with or without fee is hereby granted, provided that the above
 * copyright notice and this permission notice appear in all copies.
 *
 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 */

#include <xombrero.h>

#define TLD_TREE_END_NODE 1
#define TLD_TREE_EXCEPTION 2

struct tld_tree_node {
        struct tld_tree_node    *next;
        struct tld_tree_node    *child;
        const char              *lbl;
        char                    flags;
};

struct tld_tree_node tld_tree_root = { NULL, NULL, "" };

#define TREE_INSERT_CHILD(n, data) \
                n->child = g_malloc(sizeof *n); \
                n->child->next = NULL; \
                n->child->child = NULL; \
                n->child->flags = 0; \
                n->child->lbl = data;

#define TREE_INSERT_NEXT(n, data) \
                n->next = g_malloc(sizeof *n); \
                n->next->next = NULL; \
                n->next->child = NULL; \
                n->next->flags = 0; \
                n->next->lbl = data;

#define P_BASE          (36)
#define P_TMIN          (1)
#define P_TMAX          (26)
#define P_SKEW          (38)
#define P_DAMP          (700)
#define INITIAL_BIAS    (72)
#define INITIAL_N       (128)

int
adapt(int delta, int numpoints, int firsttime)
{
        int             k;

        if (firsttime)
                delta = delta / P_DAMP;
        else
                delta = delta / 2;

        delta += (delta / numpoints);

        k = 0;
        while (delta > (((P_BASE - P_TMIN) * P_TMAX) / 2)) {
                delta = delta / (P_BASE - P_TMIN);
                k += P_BASE;
        }

        k += (((P_BASE - P_TMIN + 1) * delta) / (delta + P_SKEW));
        return (k);
}

int
get_minimum_char(char *str, int n)
{
        gunichar        ch = 0;
        gunichar        min = 0xffffff;

        for(; *str; str = g_utf8_next_char(str)) {
                ch = g_utf8_get_char(str);
                if (ch >= n && ch < min)
                        min = ch;
        }

        return (min);
}

char
encode_digit(int n)
{
        if (n < 26)
                return n + 'a';
        return (n - 26) + '0';
}

char *
punycode_encode(char *str)
{
        char            output[1024];
        char            *s;
        gunichar        c;
        int             need_coding = 0;
        int             l, len, i;

        int             n = INITIAL_N;
        int             delta = 0;
        int             bias = INITIAL_BIAS;
        int             h, b, m, k, t, q;

        l = 0;
        for (s=str; *s; s = g_utf8_next_char(s)) {
                c = g_utf8_get_char(s);
                if (c < 128)
                        output[l++] = *s;
                else
                        need_coding = 1;
        }

        output[l] = '\0';

        if (!need_coding)
                return g_strdup(output);

        h = b = strlen(output);

        if (l > 0)
                output[l++] = '-';
        output[l] = '\0';

        len = g_utf8_strlen(str, -1);
        while (h < len) {
                m = get_minimum_char(str, n);
                delta += (m - n) * (h + 1);
                n = m;
                for (s=str; *s; s = g_utf8_next_char(s)) {
                        c = g_utf8_get_char(s);

                        if (c < n) delta ++;
                        if (c == n) {
                                q = delta;
                                for (k=P_BASE;; k+=P_BASE) {
                                        if (k <= bias)
                                                t = P_TMIN;
                                        else if(k >= bias + P_TMAX)
                                                t = P_TMAX;
                                        else
                                                t = k - bias;

                                        if (q < t)
                                                break;

                                        output[l++] = encode_digit(t+((q-t)%(P_BASE-t)));
                                        q = (q - t) / (P_BASE - t);
                                }
                                output[l++] = encode_digit(q);
                                bias = adapt(delta, h + 1, h == b);
                                delta = 0;
                                h ++;
                        }
                }
                delta ++;
                n ++;
        }

        output[l] = '\0';
        for (i=l+4;i>=4;i--)
                output[i] = output[i-4];
        l += 4;
        output[0] = 'x';
        output[1] = 'n';
        output[2] = '-';
        output[3] = '-';
        output[l] = '\0';
        return g_strdup(output);
}

/*
 * strrchr2(str, saveptr, ch)
 *
 * Walk backwards through str, jumping to next 'ch'
 * On first call, *saveptr should be set to NULL.
 * On following calls, supply the same saveptr.
 *
 * Returns NULL when the whole string 'str' has been
 * looped through. Otherwise returns the position
 * before the next 'ch'.
 */
const char *
strrchr2(const char *str, const char **saveptr, int ch)
{
        const char              *ptr;

        if (str != NULL && *saveptr == NULL) {
                *saveptr = str + strlen(str);
        } else if (str == *saveptr) {
                return (NULL);
        }

        for (ptr= *saveptr - 1; ptr != str && *ptr != ch; ptr--)
                ;

        *saveptr = ptr;
        if (ptr != str)
                return (ptr+1);
        return (ptr);
}

/*
 * tld_tree_add(rule)
 *
 * Adds a tld-rule to the tree
 */
void
tld_tree_add(const char *rule)
{
        struct tld_tree_node    *n;
        const char              *lbl;
        const char              *saveptr;

        saveptr = NULL;
        lbl = strrchr2(rule, &saveptr, '.');

        for (n = &tld_tree_root; lbl != NULL;) {

                if (strcmp(n->lbl, lbl) == 0) {
                        lbl = strrchr2(rule, &saveptr, '.');

                        if (!n->child)
                                break;

                        n = n->child;
                        continue;
                }

                if (n->next == NULL) {
                        TREE_INSERT_NEXT(n, lbl);
                        n = n->next;

                        lbl = strrchr2(rule, &saveptr, '.');
                        break;
                }
                n = n->next;
        }

        while (lbl) {
                TREE_INSERT_CHILD(n, lbl);

                lbl = strrchr2(rule, &saveptr, '.');
                n = n->child;
        }

        n->flags |= TLD_TREE_END_NODE;
        if (n->lbl[0] == '!') {
                n->flags |= TLD_TREE_EXCEPTION;
                n->lbl ++;
        }
}

void
tld_tree_init()
{
        FILE            *fd;
        char            buf[1024];
        char            file[PATH_MAX];
        char            *ptr, *next_lbl;
        char            *enc_lbl;
        char            *rule, *rp;
        char            extra_ch;

        snprintf(file, sizeof file, "%s" PS "tld-rules", resource_dir);
        fd = fopen(file, "r");
        if (fd == NULL) {
                /* a poor replacement for the real list - but it's
                 * better than nothing.
                 */
                tld_tree_add("*");
                startpage_add("Could not open %s: this file is required "
                    "to handle TLD whitelisting properly", file);
                return;
        }

        for (;;) {
                ptr = fgets(buf, sizeof buf, fd);
                if (ptr == NULL || feof(fd))
                        break;

                /* skip comments */
                if ((ptr = strstr(buf, "//")) != NULL)
                        *ptr = '\0';
                /* skip anything after space or tab */
                for (ptr = buf; *ptr; ptr++)
                        if (*ptr == ' ' || *ptr == '\t' ||
                            *ptr == '\n' || *ptr == '\r')
                                break;
                *ptr = '\0';

                if (!strlen(buf))
                        continue;

                extra_ch = 0;
                ptr = buf;
                if (buf[0] == '!' && buf[0] == '*') {
                        extra_ch = buf[0];
                        ptr ++;
                }


                rule = NULL;
                /* split into labels, and convert them one by one */
                for (;;) {
                        if ((next_lbl = strchr(ptr, '.')))
                                *next_lbl = '\0';

                        enc_lbl = punycode_encode(ptr);
                        if (rule) {
                                rp = rule;
                                rule = g_strdup_printf("%s%s%s", rp, enc_lbl,
                                    next_lbl ? "." : "");
                                g_free(rp);
                                g_free(enc_lbl);
                        } else {
                                rule = g_strdup_printf("%.1s%s%s",
                                    extra_ch ? buf:"", enc_lbl,
                                    next_lbl ? ".":"");
                                g_free(enc_lbl);
                        }

                        if (!next_lbl)
                                break;
                        ptr = next_lbl + 1;
                }
                tld_tree_add(rule);
        }

        fclose(fd);
}

/*
 * tld_get_suffix(domain)
 *
 * Find the public suffix for domain.
 *
 * Returns a pointer to the suffix position
 * in domain, or NULL if no public suffix
 * was found.
 */
char *
tld_get_suffix(const char *domain)
{
        struct tld_tree_node    *n;
        const char              *suffix;
        const char              *lbl, *saveptr;
        const char              *tmp_saveptr, *tmp_lbl;

        if (domain == NULL)
                return (NULL);
        if (domain[0] == '.')
                return (NULL);

        saveptr = NULL;
        suffix = NULL;
        lbl = strrchr2(domain, &saveptr, '.');

        for (n = &tld_tree_root; n != NULL && lbl != NULL;) {

                if (!strlen(n->lbl)) {
                        n = n->next;
                        continue;
                }

                if (n->lbl[0] == '*') {
                        if (n->flags & TLD_TREE_END_NODE) {

                                tmp_saveptr = saveptr;
                                tmp_lbl = lbl;

                                lbl = strrchr2(domain, &saveptr, '.');

                                /* Save possible public suffix */
                                suffix = lbl;
                                saveptr = tmp_saveptr;
                                lbl = tmp_lbl;
                        }

                        n = n->next;
                        continue;
                }

                if (strcmp(n->lbl, lbl) == 0) {
                        if (n->flags & TLD_TREE_EXCEPTION) {
                                /* We're done looking */
                                suffix = lbl;
                                break;
                        }

                        lbl = strrchr2(domain, &saveptr, '.');

                        /* Possible public suffix - other rules might
                         * still apply
                         */
                        if (n->flags & TLD_TREE_END_NODE)
                                suffix = lbl;

                        /* Domain too short */
                        if (lbl == NULL) {
                                /* Check if we have a child that is '*' */
                                for (n = n->child; n; n = n->next)
                                        if (n->lbl[0] == '*')
                                                suffix = NULL;
                                break;
                        }

                        if (n->child == NULL)
                                break;

                        n = n->child;
                        continue;
                }

                if (n->next == NULL)
                        break;
                n = n->next;
        }

        /* If we can't find a matching suffix, it can mean that either
         * a) the user is surfing a local prefix
         * b) the list is not properly updated
         *
         * In any case - in order not to break stuff while surfing
         * new TLD's, we return the public suffix as the top 2 labels
         *
         * www.abc.xyz therefore has public suffix 'abc.xyz'
         */
        if (!suffix) {
                saveptr = NULL;
                lbl = strrchr2(domain, &saveptr, '.');
                lbl = strrchr2(domain, &saveptr, '.');
                suffix = lbl;
        }

        return ((char*)suffix);
}