path: root/e-util/e-html-utils.c

/*
 * This program is free software; you can redistribute it and/or modify it
 * under the terms of the GNU Lesser General Public License as published by
 * the Free Software Foundation.
 *
 * This program 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 Lesser General Public License
 * along with this program; if not, see <http://www.gnu.org/licenses/>.
 *
 *
 * Authors:
 *      Dan Winship <danw@ximian.com>
 *
 * Copyright (C) 1999-2008 Novell, Inc. (www.novell.com)
 *
 */

#ifdef HAVE_CONFIG_H
#include <config.h>
#endif

#include <ctype.h>
#include <stdio.h>
#include <string.h>

#include "e-html-utils.h"

static gchar *
check_size (gchar **buffer,
            gint *buffer_size,
            gchar *out,
            gint len)
{
    if (out + len + 1> *buffer + *buffer_size) {
        gint index = out - *buffer;

        *buffer_size = MAX (index + len + 1, *buffer_size * 2);
        *buffer = g_realloc (*buffer, *buffer_size);
        out = *buffer + index;
    }
    return out;
}

/* auto-urlification hints: the goal is not to be strictly RFC-compliant,
 * but rather to accurately distinguish urls/addresses from non-urls/
 * addresses in real-world email.
 *
 * 1 = non-email-address chars: ()<>@,;:\"[]`'{}|
 * 2 = trailing url garbage:    ,.!?;:>)]}`'-_
 * 4 = allowed dns chars
 * 8 = non-url chars:           "|
 */
static gint special_chars[] = {
    9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9,    /*  nul - 0x0f */
    9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9,    /* 0x10 - 0x1f */
    9, 2, 9, 0, 0, 0, 0, 3, 1, 3, 0, 0, 3, 6, 6, 0,    /*   sp - /    */
    4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 3, 3, 1, 0, 3, 2,    /*    0 - ?    */
    1, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4,    /*    @ - O    */
    4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 1, 1, 3, 0, 2,    /*    P - _    */
    3, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4,    /*    ` - o    */
    4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 1, 9, 3, 0, 3     /*    p - del  */
};

#define is_addr_char(c) (c < 128 && !(special_chars[c] & 1))
#define is_url_char(c) (c < 128 && !(special_chars[c] & 8))
#define is_trailing_garbage(c) (c > 127 || (special_chars[c] & 2))
#define is_domain_name_char(c) (c < 128 && (special_chars[c] & 4))

/* (http|https|ftp|nntp)://[^ "|/]+\.([^ "|]*[^ ,.!?;:>)\]}`'"|_-])+ */
/* www\.[A-Za-z0-9.-]+(/([^ "|]*[^ ,.!?;:>)\]}`'"|_-])+)             */

static gchar *
url_extract (const guchar **text,
             gboolean full_url)
{
    const guchar *end = *text, *p;
    gchar *out;

    while (*end && is_url_char (*end))
        end++;

    /* Back up if we probably went too far. */
    while (end > *text && is_trailing_garbage (*(end - 1)))
        end--;

    if (full_url) {
        /* Make sure this really looks like a URL. */
        p = memchr (*text, ':', end - *text);
        if (!p || end - p < 4)
            return NULL;
    } else {
        /* Make sure this really looks like a hostname. */
        p = memchr (*text, '.', end - *text);
        if (!p || p >= end - 2)
            return NULL;
        p = memchr (p + 2, '.', end - (p + 2));
        if (!p || p >= end - 2)
            return NULL;
    }

    out = g_strndup ((gchar *) * text, end - *text);
    *text = end;
    return out;
}

static gchar *
email_address_extract (const guchar **cur,
                       gchar **out,
                       const guchar *linestart)
{
    const guchar *start, *end, *dot;
    gchar *addr;

    /* *cur points to the '@'. Look backward for a valid local-part */
    for (start = *cur; start - 1 >= linestart && is_addr_char (*(start - 1)); start--)
        ;
    if (start == *cur)
        return NULL;
    if (start > linestart + 2 &&
        start[-1] == ':' && start[0] == '/' && start[1] == '/')
        return NULL;

    /* Now look forward for a valid domain part */
    for (end = *cur + 1, dot = NULL; is_domain_name_char (*end); end++) {
        if (*end == '.' && !dot)
            dot = end;
    }
    if (!dot)
        return NULL;

    /* Remove trailing garbage */
    while (is_trailing_garbage (*(end - 1)))
        end--;
    if (dot > end)
        return NULL;

    addr = g_strndup ((gchar *) start, end - start);
    *out -= *cur - start;
    *cur = end;

    return addr;
}

static gboolean
is_citation (const guchar *c,
             gboolean saw_citation)
{
    const guchar *p;

    if (*c != '>')
        return FALSE;

    /* A line that starts with a ">" is a citation, unless it's
     * just mbox From-mangling...
     */
    if (strncmp ((const gchar *) c, ">From ", 6) != 0)
        return TRUE;

    /* If the previous line was a citation, then say this
     * one is too.
     */
    if (saw_citation)
        return TRUE;

    /* Same if the next line is */
    p = (const guchar *) strchr ((const gchar *) c, '\n');
    if (p && *++p == '>')
        return TRUE;

    /* Otherwise, it was just an isolated ">From" line. */
    return FALSE;
}

/**
 * e_text_to_html_full:
 * @input: a NUL-terminated input buffer
 * @flags: some combination of the E_TEXT_TO_HTML_* flags defined
 * in e-html-utils.h
 * @color: color for citation highlighting
 *
 * This takes a buffer of text as input and produces a buffer of
 * "equivalent" HTML, subject to certain transformation rules.
 *
 * The set of possible flags is:
 *
 *   - E_TEXT_TO_HTML_PRE: wrap the output HTML in &lt;PRE&gt; and
 *     &lt;/PRE&gt;  Should only be used if @input is the entire
 *     buffer to be converted. If e_text_to_html is being called with
 *     small pieces of data, you should wrap the entire result in
 *     &lt;PRE&gt; yourself.
 *
 *   - E_TEXT_TO_HTML_CONVERT_NL: convert "\n" to "&lt;BR&gt;n" on
 *     output.  (Should not be used with E_TEXT_TO_HTML_PRE, since
 *     that would result in double-newlines.)
 *
 *   - E_TEXT_TO_HTML_CONVERT_SPACES: convert a block of N spaces
 *     into N-1 non-breaking spaces and one normal space. A space
 *     at the start of the buffer is always converted to a
 *     non-breaking space, regardless of the following character,
 *     which probably means you don't want to use this flag on
 *     pieces of data that aren't delimited by at least line breaks.
 *
 *     If E_TEXT_TO_HTML_CONVERT_NL and E_TEXT_TO_HTML_CONVERT_SPACES
 *     are both defined, then TABs will also be converted to spaces.
 *
 *   - E_TEXT_TO_HTML_CONVERT_URLS: wrap &lt;a href="..."&gt; &lt;/a&gt;
 *     around strings that look like URLs.
 *
 *   - E_TEXT_TO_HTML_CONVERT_ADDRESSES: wrap &lt;a href="mailto:..."&gt;
 *     &lt;/a&gt; around strings that look like mail addresses.
 *
 *   - E_TEXT_TO_HTML_MARK_CITATION: wrap &lt;font color="..."&gt;
 *     &lt;/font&gt; around citations (lines beginning with "> ", etc).
 *
 *   - E_TEXT_TO_HTML_ESCAPE_8BIT: flatten everything to US-ASCII
 *
 *   - E_TEXT_TO_HTML_CITE: quote the text with "> " at the start of each
 *     line.
 *
 * Returns: a newly-allocated string containing HTML
 **/
gchar *
e_text_to_html_full (const gchar *input,
                     guint flags,
                     guint32 color)
{
    const guchar *cur, *next, *linestart;
    gchar *buffer = NULL;
    gchar *out = NULL;
    gint buffer_size = 0, col;
    gboolean colored = FALSE, saw_citation = FALSE;

    /* Allocate a translation buffer.  */
    buffer_size = strlen (input) * 2 + 5;
    buffer = g_malloc (buffer_size);

    out = buffer;
    if (flags & E_TEXT_TO_HTML_PRE)
        out += sprintf (out, "<PRE>");

    col = 0;

    for (cur = linestart = (const guchar *) input; cur && *cur; cur = next) {
        gunichar u;

        if (flags & E_TEXT_TO_HTML_MARK_CITATION && col == 0) {
            saw_citation = is_citation (cur, saw_citation);
            if (saw_citation) {
                if (!colored) {
                    gchar font[25];

                    g_snprintf (font, 25, "<FONT COLOR=\"#%06x\">", color);

                    out = check_size (&buffer, &buffer_size, out, 25);
                    out += sprintf (out, "%s", font);
                    colored = TRUE;
                }
            } else if (colored) {
                const gchar *no_font = "</FONT>";

                out = check_size (&buffer, &buffer_size, out, 9);
                out += sprintf (out, "%s", no_font);
                colored = FALSE;
            }

            /* Display mbox-mangled ">From" as "From" */
            if (*cur == '>' && !saw_citation)
                cur++;
        } else if (flags & E_TEXT_TO_HTML_CITE && col == 0) {
            out = check_size (&buffer, &buffer_size, out, 5);
            out += sprintf (out, "&gt; ");
        }

        u = g_utf8_get_char ((gchar *) cur);
        if (g_unichar_isalpha (u) &&
            (flags & E_TEXT_TO_HTML_CONVERT_URLS)) {
            gchar *tmpurl = NULL, *refurl = NULL, *dispurl = NULL;

            if (!g_ascii_strncasecmp ((gchar *) cur, "http://", 7) ||
                !g_ascii_strncasecmp ((gchar *) cur, "https://", 8) ||
                !g_ascii_strncasecmp ((gchar *) cur, "ftp://", 6) ||
                !g_ascii_strncasecmp ((gchar *) cur, "nntp://", 7) ||
                !g_ascii_strncasecmp ((gchar *) cur, "mailto:", 7) ||
                !g_ascii_strncasecmp ((gchar *) cur, "news:", 5) ||
                !g_ascii_strncasecmp ((gchar *) cur, "file:", 5) ||
                !g_ascii_strncasecmp ((gchar *) cur, "callto:", 7) ||
                !g_ascii_strncasecmp ((gchar *) cur, "h323:", 5) ||
                !g_ascii_strncasecmp ((gchar *) cur, "sip:", 4) ||
                !g_ascii_strncasecmp ((gchar *) cur, "webcal:", 7)) {
                tmpurl = url_extract (&cur, TRUE);
                if (tmpurl) {
                    refurl = e_text_to_html (tmpurl, 0);
                    dispurl = g_strdup (refurl);
                }
            } else if (!g_ascii_strncasecmp ((gchar *) cur, "www.", 4) &&
                   is_url_char (*(cur + 4))) {
                tmpurl = url_extract (&cur, FALSE);
                if (tmpurl) {
                    dispurl = e_text_to_html (tmpurl, 0);
                    refurl = g_strdup_printf (
                        "http://%s", dispurl);
                }
            }

            if (tmpurl) {
                out = check_size (
                    &buffer, &buffer_size, out,
                    strlen (refurl) +
                    strlen (dispurl) + 15);
                out += sprintf (out,
                        "<a href=\"%s\">%s</a>",
                        refurl, dispurl);
                col += strlen (tmpurl);
                g_free (tmpurl);
                g_free (refurl);
                g_free (dispurl);
            }

            if (!*cur)
                break;
            u = g_utf8_get_char ((gchar *) cur);
        }

        if (u == '@' && (flags & E_TEXT_TO_HTML_CONVERT_ADDRESSES)) {
            gchar *addr, *dispaddr, *outaddr;

            addr = email_address_extract (&cur, &out, linestart);
            if (addr) {
                dispaddr = e_text_to_html (addr, 0);
                outaddr = g_strdup_printf (
                    "<a href=\"mailto:%s\">%s</a>",
                    addr, dispaddr);
                out = check_size (&buffer, &buffer_size, out, strlen (outaddr));
                out += sprintf (out, "%s", outaddr);
                col += strlen (addr);
                g_free (addr);
                g_free (dispaddr);
                g_free (outaddr);

                if (!*cur)
                    break;
                u = g_utf8_get_char ((gchar *) cur);
            }
        }

        if (!g_unichar_validate (u)) {
            /* Sigh. Someone sent undeclared 8-bit data.
             * Assume it's iso-8859-1.
             */
            u = *cur;
            next = cur + 1;
        } else
            next = (const guchar *) g_utf8_next_char (cur);

        out = check_size (&buffer, &buffer_size, out, 10);

        switch (u) {
        case '<':
            strcpy (out, "&lt;");
            out += 4;
            col++;
            break;

        case '>':
            strcpy (out, "&gt;");
            out += 4;
            col++;
            break;

        case '&':
            strcpy (out, "&amp;");
            out += 5;
            col++;
            break;

        case '"':
            strcpy (out, "&quot;");
            out += 6;
            col++;
            break;

        case '\n':
            if (flags & E_TEXT_TO_HTML_CONVERT_NL) {
                strcpy (out, "<br>");
                out += 4;
            }
            *out++ = *cur;
            linestart = cur;
            col = 0;
            break;

        case '\t':
            if (flags & (E_TEXT_TO_HTML_CONVERT_SPACES |
                     E_TEXT_TO_HTML_CONVERT_NL)) {
                do {
                    out = check_size (
                        &buffer, &buffer_size, out, 7);
                    strcpy (out, "&nbsp;");
                    out += 6;
                    col++;
                } while (col % 8);
                break;
            }
            /* otherwise, FALL THROUGH */

        case ' ':
            if (flags & E_TEXT_TO_HTML_CONVERT_SPACES) {
                if (cur == (const guchar *) input ||
                    *(cur + 1) == ' ' || *(cur + 1) == '\t' ||
                    *(cur - 1) == '\n') {
                    strcpy (out, "&nbsp;");
                    out += 6;
                    col++;
                    break;
                }
            }
            /* otherwise, FALL THROUGH */

        default:
            if ((u >= 0x20 && u < 0x80) ||
                (u == '\r' || u == '\t')) {
                /* Default case, just copy. */
                *out++ = u;
            } else {
                if (flags & E_TEXT_TO_HTML_ESCAPE_8BIT)
                    *out++ = '?';
                else
                    out += g_snprintf (out, 9, "&#%d;", u);
            }
            col++;
            break;
        }
    }

    out = check_size (&buffer, &buffer_size, out, 7);
    if (flags & E_TEXT_TO_HTML_PRE)
        strcpy (out, "</PRE>");
    else
        *out = '\0';

    return buffer;
}

gchar *
e_text_to_html (const gchar *input,
                guint flags)
{
    return e_text_to_html_full (input, flags, 0);
}

#ifdef E_HTML_UTILS_TEST

struct {
    gchar *text, *url;
} url_tests[] = {
    { "bob@foo.com", "mailto:bob@foo.com" },
    { "Ends with bob@foo.com", "mailto:bob@foo.com" },
    { "bob@foo.com at start", "mailto:bob@foo.com" },
    { "bob@foo.com.", "mailto:bob@foo.com" },
    { "\"bob@foo.com\"", "mailto:bob@foo.com" },
    { "<bob@foo.com>", "mailto:bob@foo.com" },
    { "(bob@foo.com)", "mailto:bob@foo.com" },
    { "bob@foo.com, 555-9999", "mailto:bob@foo.com" },
    { "|bob@foo.com|555-9999|", "mailto:bob@foo.com" },
    { "bob@ no match bob@", NULL },
    { "@foo.com no match @foo.com", NULL },
    { "\"bob\"@foo.com", NULL },
    { "M@ke money fast!", NULL },
    { "ASCII art @_@ @>->-", NULL },

    { "http://www.foo.com", "http://www.foo.com" },
    { "Ends with http://www.foo.com", "http://www.foo.com" },
    { "http://www.foo.com at start", "http://www.foo.com" },
    { "http://www.foo.com.", "http://www.foo.com" },
    { "http://www.foo.com/.", "http://www.foo.com/" },
    { "<http://www.foo.com>", "http://www.foo.com" },
    { "(http://www.foo.com)", "http://www.foo.com" },
    { "http://www.foo.com, 555-9999", "http://www.foo.com" },
    { "|http://www.foo.com|555-9999|", "http://www.foo.com" },
    { "foo http://www.foo.com/ bar", "http://www.foo.com/" },
    { "foo http://www.foo.com/index.html bar",
      "http://www.foo.com/index.html" },
    { "foo http://www.foo.com/q?99 bar", "http://www.foo.com/q?99" },
    { "foo http://www.foo.com/;foo=bar&baz=quux bar",
      "http://www.foo.com/;foo=bar&baz=quux" },
    { "foo http://www.foo.com/index.html#anchor bar",
      "http://www.foo.com/index.html#anchor" },
    { "http://www.foo.com/index.html; foo",
      "http://www.foo.com/index.html" },
    { "http://www.foo.com/index.html: foo",
      "http://www.foo.com/index.html" },
    { "http://www.foo.com/index.html-- foo",
      "http://www.foo.com/index.html" },
    { "http://www.foo.com/index.html?",
      "http://www.foo.com/index.html" },
    { "http://www.foo.com/index.html!",
      "http://www.foo.com/index.html" },
    { "\"http://www.foo.com/index.html\"",
      "http://www.foo.com/index.html" },
    { "'http://www.foo.com/index.html'",
      "http://www.foo.com/index.html" },
    { "http://bob@www.foo.com/bar/baz/",
      "http://bob@www.foo.com/bar/baz/" },
    { "http no match http", NULL },
    { "http: no match http:", NULL },
    { "http:// no match http://", NULL },
    { "unrecognized://bob@foo.com/path", NULL },

    { "src/www.c", NULL },
    { "Ewwwwww.Gross.", NULL },

};
gint num_url_tests = G_N_ELEMENTS (url_tests);

gint
main (gint argc,
      gchar **argv)
{
    gint i, errors = 0;
    gchar *html, *url, *p;

    for (i = 0; i < num_url_tests; i++) {
        html = e_text_to_html (
            url_tests[i].text,
            E_TEXT_TO_HTML_CONVERT_URLS |
            E_TEXT_TO_HTML_CONVERT_ADDRESSES);

        url = strstr (html, "href=\"");
        if (url) {
            url += 6;
            p = strchr (url, '"');
            if (p)
                *p = '\0';

            while ((p = strstr (url, "&amp;")))
                memmove (p + 1, p + 5, strlen (p + 5) + 1);
        }

        if ((url && (!url_tests[i].url || strcmp (url, url_tests[i].url) != 0)) ||
            (!url && url_tests[i].url)) {
            printf (
                "FAILED on \"%s\" -> %s\n  (got %s)\n\n",
                url_tests[i].text,
                url_tests[i].url ? url_tests[i].url : "(nothing)",
                url ? url : "(nothing)");
            errors++;
        }

        g_free (html);
    }

    printf ("\n%d errors\n", errors);
    return errors;
}
#endif