/* $OpenBSD: cgi.c,v 1.120 2022/12/26 19:16:02 jmc Exp $ */
/*
 * Copyright (c) 2014-2019, 2021, 2022 Ingo Schwarze <schwarze@usta.de>
 * Copyright (c) 2011, 2012 Kristaps Dzonsons <kristaps@bsd.lv>
 * Copyright (c) 2022 Anna Vyalkova <cyber@sysrq.in>
 *
 * 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 AUTHORS DISCLAIM ALL WARRANTIES
 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHORS 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.
 *
 * Implementation of the man.cgi(8) program.
 */
#include <sys/types.h>
#include <sys/time.h>

#include <ctype.h>
#include <err.h>
#include <errno.h>
#include <fcntl.h>
#include <limits.h>
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>

#include "mandoc_aux.h"
#include "mandoc.h"
#include "roff.h"
#include "mdoc.h"
#include "man.h"
#include "mandoc_parse.h"
#include "main.h"
#include "manconf.h"
#include "mansearch.h"
#include "cgi.h"

/*
 * A query as passed to the search function.
 */
struct  query {
        char            *manpath; /* desired manual directory */
        char            *arch; /* architecture */
        char            *sec; /* manual section */
        char            *query; /* unparsed query expression */
        int              equal; /* match whole names, not substrings */
};

struct  req {
        struct query      q;
        char            **p; /* array of available manpaths */
        size_t            psz; /* number of available manpaths */
        int               isquery; /* QUERY_STRING used, not PATH_INFO */
};

enum    focus {
        FOCUS_NONE = 0,
        FOCUS_QUERY
};

static  void             html_print(const char *);
static  void             html_putchar(char);
static  int              http_decode(char *);
static  void             http_encode(const char *);
static  void             parse_manpath_conf(struct req *);
static  void             parse_path_info(struct req *, const char *);
static  void             parse_query_string(struct req *, const char *);
static  void             pg_error_badrequest(const char *);
static  void             pg_error_internal(void);
static  void             pg_index(const struct req *);
static  void             pg_noresult(const struct req *, int, const char *,
                                const char *);
static  void             pg_redirect(const struct req *, const char *);
static  void             pg_search(const struct req *);
static  void             pg_searchres(const struct req *,
                                struct manpage *, size_t);
static  void             pg_show(struct req *, const char *);
static  int              resp_begin_html(int, const char *, const char *);
static  void             resp_begin_http(int, const char *);
static  void             resp_catman(const struct req *, const char *);
static  int              resp_copy(const char *, const char *);
static  void             resp_end_html(void);
static  void             resp_format(const struct req *, const char *);
static  void             resp_searchform(const struct req *, enum focus);
static  void             resp_show(const struct req *, const char *);
static  void             set_query_attr(char **, char **);
static  int              validate_arch(const char *);
static  int              validate_filename(const char *);
static  int              validate_manpath(const struct req *, const char *);
static  int              validate_urifrag(const char *);

static  const char       *scriptname = SCRIPT_NAME;

static  const int sec_prios[] = {1, 4, 5, 8, 6, 3, 7, 2, 9};
static  const char *const sec_numbers[] = {
    "0", "1", "2", "3", "3p", "4", "5", "6", "7", "8", "9"
};
static  const char *const sec_names[] = {
    "All Sections",
    "1 - General Commands",
    "2 - System Calls",
    "3 - Library Functions",
    "3p - Perl Library",
    "4 - Device Drivers",
    "5 - File Formats",
    "6 - Games",
    "7 - Miscellaneous Information",
    "8 - System Manager\'s Manual",
    "9 - Kernel Developer\'s Manual"
};
static  const int sec_MAX = sizeof(sec_names) / sizeof(char *);

static  const char *const arch_names[] = {
    "amd64",       "alpha",       "armv7",       "arm64",
    "hppa",        "i386",        "landisk",     "loongson",
    "luna88k",     "macppc",      "mips64",      "octeon",
    "powerpc64",   "riscv64",     "sparc64",

    "amiga",       "arc",         "armish",      "arm32",
    "atari",       "aviion",      "beagle",      "cats",
    "hppa64",      "hp300",
    "ia64",        "mac68k",      "mvme68k",     "mvme88k",
    "mvmeppc",     "palm",        "pc532",       "pegasos",
    "pmax",        "powerpc",     "sgi",         "socppc",
    "solbourne",   "sparc",
    "sun3",        "vax",         "wgrisc",      "x68k",
    "zaurus"
};
static  const int arch_MAX = sizeof(arch_names) / sizeof(char *);

/*
 * Print a character, escaping HTML along the way.
 * This will pass non-ASCII straight to output: be warned!
 */
static void
html_putchar(char c)
{

        switch (c) {
        case '"':
                printf("&quot;");
                break;
        case '&':
                printf("&amp;");
                break;
        case '>':
                printf("&gt;");
                break;
        case '<':
                printf("&lt;");
                break;
        default:
                putchar((unsigned char)c);
                break;
        }
}

/*
 * Call through to html_putchar().
 * Accepts NULL strings.
 */
static void
html_print(const char *p)
{

        if (NULL == p)
                return;
        while ('\0' != *p)
                html_putchar(*p++);
}

/*
 * Transfer the responsibility for the allocated string *val
 * to the query structure.
 */
static void
set_query_attr(char **attr, char **val)
{

        free(*attr);
        if (**val == '\0') {
                *attr = NULL;
                free(*val);
        } else
                *attr = *val;
        *val = NULL;
}

/*
 * Parse the QUERY_STRING for key-value pairs
 * and store the values into the query structure.
 */
static void
parse_query_string(struct req *req, const char *qs)
{
        char            *key, *val;
        size_t           keysz, valsz;

        req->isquery    = 1;
        req->q.manpath  = NULL;
        req->q.arch     = NULL;
        req->q.sec      = NULL;
        req->q.query    = NULL;
        req->q.equal    = 1;

        key = val = NULL;
        while (*qs != '\0') {

                /* Parse one key. */

                keysz = strcspn(qs, "=;&");
                key = mandoc_strndup(qs, keysz);
                qs += keysz;
                if (*qs != '=')
                        goto next;

                /* Parse one value. */

                valsz = strcspn(++qs, ";&");
                val = mandoc_strndup(qs, valsz);
                qs += valsz;

                /* Decode and catch encoding errors. */

                if ( ! (http_decode(key) && http_decode(val)))
                        goto next;

                /* Handle key-value pairs. */

                if ( ! strcmp(key, "query"))
                        set_query_attr(&req->q.query, &val);

                else if ( ! strcmp(key, "apropos"))
                        req->q.equal = !strcmp(val, "0");

                else if ( ! strcmp(key, "manpath")) {
#ifdef COMPAT_OLDURI
                        if ( ! strncmp(val, "OpenBSD ", 8)) {
                                val[7] = '-';
                                if ('C' == val[8])
                                        val[8] = 'c';
                        }
#endif
                        set_query_attr(&req->q.manpath, &val);
                }

                else if ( ! (strcmp(key, "sec")
#ifdef COMPAT_OLDURI
                    && strcmp(key, "sektion")
#endif
                    )) {
                        if ( ! strcmp(val, "0"))
                                *val = '\0';
                        set_query_attr(&req->q.sec, &val);
                }

                else if ( ! strcmp(key, "arch")) {
                        if ( ! strcmp(val, "default"))
                                *val = '\0';
                        set_query_attr(&req->q.arch, &val);
                }

                /*
                 * The key must be freed in any case.
                 * The val may have been handed over to the query
                 * structure, in which case it is now NULL.
                 */
next:
                free(key);
                key = NULL;
                free(val);
                val = NULL;

                if (*qs != '\0')
                        qs++;
        }
}

/*
 * HTTP-decode a string.  The standard explanation is that this turns
 * "%4e+foo" into "n foo" in the regular way.  This is done in-place
 * over the allocated string.
 */
static int
http_decode(char *p)
{
        char             hex[3];
        char            *q;
        int              c;

        hex[2] = '\0';

        q = p;
        for ( ; '\0' != *p; p++, q++) {
                if ('%' == *p) {
                        if ('\0' == (hex[0] = *(p + 1)))
                                return 0;
                        if ('\0' == (hex[1] = *(p + 2)))
                                return 0;
                        if (1 != sscanf(hex, "%x", &c))
                                return 0;
                        if ('\0' == c)
                                return 0;

                        *q = (char)c;
                        p += 2;
                } else
                        *q = '+' == *p ? ' ' : *p;
        }

        *q = '\0';
        return 1;
}

static void
http_encode(const char *p)
{
        for (; *p != '\0'; p++) {
                if (isalnum((unsigned char)*p) == 0 &&
                    strchr("-._~", *p) == NULL)
                        printf("%%%2.2X", (unsigned char)*p);
                else
                        putchar(*p);
        }
}

static void
resp_begin_http(int code, const char *msg)
{

        if (200 != code)
                printf("Status: %d %s\r\n", code, msg);

        printf("Content-Type: text/html; charset=utf-8\r\n"
             "Cache-Control: no-cache\r\n"
             "Content-Security-Policy: default-src 'none'; "
             "style-src 'self' 'unsafe-inline'\r\n"
             "Pragma: no-cache\r\n"
             "\r\n");

        fflush(stdout);
}

static int
resp_copy(const char *element, const char *filename)
{
        char     buf[4096];
        ssize_t  sz;
        int      fd;

        if ((fd = open(filename, O_RDONLY)) == -1)
                return 0;

        if (element != NULL)
                printf("<%s>\n", element);
        fflush(stdout);
        while ((sz = read(fd, buf, sizeof(buf))) > 0)
                write(STDOUT_FILENO, buf, sz);
        close(fd);
        return 1;
}

static int
resp_begin_html(int code, const char *msg, const char *file)
{
        const char      *name, *sec, *cp;
        int              namesz, secsz;

        resp_begin_http(code, msg);

        printf("<!DOCTYPE html>\n"
               "<html>\n"
               "<head>\n"
               "  <meta charset=\"UTF-8\"/>\n"
               "  <meta name=\"viewport\""
                      " content=\"width=device-width, initial-scale=1.0\">\n"
               "  <link rel=\"stylesheet\" href=\"%s/mandoc.css\""
               " type=\"text/css\" media=\"all\">\n"
               "  <title>",
               CSS_DIR);
        if (file != NULL) {
                cp = strrchr(file, '/');
                name = cp == NULL ? file : cp + 1;
                cp = strrchr(name, '.');
                namesz = cp == NULL ? strlen(name) : cp - name;
                sec = NULL;
                if (cp != NULL && cp[1] != '0') {
                        sec = cp + 1;
                        secsz = strlen(sec);
                } else if (name - file > 1) {
                        for (cp = name - 2; cp >= file; cp--) {
                                if (*cp < '1' || *cp > '9')
                                        continue;
                                sec = cp;
                                secsz = name - cp - 1;
                                break;
                        }
                }
                printf("%.*s", namesz, name);
                if (sec != NULL)
                        printf("(%.*s)", secsz, sec);
                fputs(" - ", stdout);
        }
        printf("%s</title>\n"
               "</head>\n"
               "<body>\n",
               CUSTOMIZE_TITLE);

        return resp_copy("header", MAN_DIR "/header.html");
}

static void
resp_end_html(void)
{
        if (resp_copy("footer", MAN_DIR "/footer.html"))
                puts("</footer>");

        puts("</body>\n"
             "</html>");
}

static void
resp_searchform(const struct req *req, enum focus focus)
{
        int              i;

        printf("<form role=\"search\" action=\"/%s\" method=\"get\" "
               "autocomplete=\"off\" autocapitalize=\"none\">\n"
               "  <fieldset>\n"
               "    <legend>Manual Page Search Parameters</legend>\n",
               scriptname);

        /* Write query input box. */

        printf("    <label>Search query:\n"
               "      <input type=\"search\" name=\"query\" value=\"");
        if (req->q.query != NULL)
                html_print(req->q.query);
        printf("\" size=\"40\"");
        if (focus == FOCUS_QUERY)
                printf(" autofocus");
        puts(">\n    </label>");

        /* Write submission buttons. */

        printf( "    <button type=\"submit\" name=\"apropos\" value=\"0\">"
                "man</button>\n"
                "    <button type=\"submit\" name=\"apropos\" value=\"1\">"
                "apropos</button>\n"
                "    <br/>\n");

        /* Write section selector. */

        puts("    <select name=\"sec\" aria-label=\"Manual section\">");
        for (i = 0; i < sec_MAX; i++) {
                printf("      <option value=\"%s\"", sec_numbers[i]);
                if (NULL != req->q.sec &&
                    0 == strcmp(sec_numbers[i], req->q.sec))
                        printf(" selected=\"selected\"");
                printf(">%s</option>\n", sec_names[i]);
        }
        puts("    </select>");

        /* Write architecture selector. */

        printf( "    <select name=\"arch\" aria-label=\"CPU architecture\">\n"
                "      <option value=\"default\"");
        if (NULL == req->q.arch)
                printf(" selected=\"selected\"");
        puts(">All Architectures</option>");
        for (i = 0; i < arch_MAX; i++) {
                printf("      <option");
                if (NULL != req->q.arch &&
                    0 == strcmp(arch_names[i], req->q.arch))
                        printf(" selected=\"selected\"");
                printf(">%s</option>\n", arch_names[i]);
        }
        puts("    </select>");

        /* Write manpath selector. */

        if (req->psz > 1) {
                puts("    <select name=\"manpath\""
                     " aria-label=\"Manual path\">");
                for (i = 0; i < (int)req->psz; i++) {
                        printf("      <option");
                        if (strcmp(req->q.manpath, req->p[i]) == 0)
                                printf(" selected=\"selected\"");
                        printf(">");
                        html_print(req->p[i]);
                        puts("</option>");
                }
                puts("    </select>");
        }

        puts("  </fieldset>\n"
             "</form>");
}

static int
validate_urifrag(const char *frag)
{

        while ('\0' != *frag) {
                if ( ! (isalnum((unsigned char)*frag) ||
                    '-' == *frag || '.' == *frag ||
                    '/' == *frag || '_' == *frag))
                        return 0;
                frag++;
        }
        return 1;
}

static int
validate_manpath(const struct req *req, const char* manpath)
{
        size_t   i;

        for (i = 0; i < req->psz; i++)
                if ( ! strcmp(manpath, req->p[i]))
                        return 1;

        return 0;
}

static int
validate_arch(const char *arch)
{
        int      i;

        for (i = 0; i < arch_MAX; i++)
                if (strcmp(arch, arch_names[i]) == 0)
                        return 1;

        return 0;
}

static int
validate_filename(const char *file)
{

        if ('.' == file[0] && '/' == file[1])
                file += 2;

        return ! (strstr(file, "../") || strstr(file, "/..") ||
            (strncmp(file, "man", 3) && strncmp(file, "cat", 3)));
}

static void
pg_index(const struct req *req)
{
        if (resp_begin_html(200, NULL, NULL) == 0)
                puts("<header>");
        resp_searchform(req, FOCUS_QUERY);
        printf("</header>\n"
               "<main>\n"
               "<p role=\"doc-notice\" aria-label=\"Usage\">\n"
               "This web interface is documented in the\n"
               "<a class=\"Xr\" href=\"/%s%sman.cgi.8\""
               " aria-label=\"man dot CGI, section 8\">man.cgi(8)</a>\n"
               "manual, and the\n"
               "<a class=\"Xr\" href=\"/%s%sapropos.1\""
               " aria-label=\"apropos, section 1\">apropos(1)</a>\n"
               "manual explains the query syntax.\n"
               "</p>\n"
               "</main>\n",
               scriptname, *scriptname == '\0' ? "" : "/",
               scriptname, *scriptname == '\0' ? "" : "/");
        resp_end_html();
}

static void
pg_noresult(const struct req *req, int code, const char *http_msg,
    const char *user_msg)
{
        if (resp_begin_html(code, http_msg, NULL) == 0)
                puts("<header>");
        resp_searchform(req, FOCUS_QUERY);
        puts("</header>");
        puts("<main>");
        puts("<p role=\"doc-notice\" aria-label=\"No result\">");
        puts(user_msg);
        puts("</p>");
        puts("</main>");
        resp_end_html();
}

static void
pg_error_badrequest(const char *msg)
{
        if (resp_begin_html(400, "Bad Request", NULL))
                puts("</header>");
        puts("<main>\n"
             "<h1>Bad Request</h1>\n"
             "<p role=\"doc-notice\" aria-label=\"Bad Request\">");
        puts(msg);
        printf("Try again from the\n"
               "<a href=\"/%s\">main page</a>.\n"
               "</p>\n"
               "</main>\n", scriptname);
        resp_end_html();
}

static void
pg_error_internal(void)
{
        if (resp_begin_html(500, "Internal Server Error", NULL))
                puts("</header>");
        puts("<main><p role=\"doc-notice\">Internal Server Error</p></main>");
        resp_end_html();
}

static void
pg_redirect(const struct req *req, const char *name)
{
        printf("Status: 303 See Other\r\n"
            "Location: /");
        if (*scriptname != '\0')
                printf("%s/", scriptname);
        if (strcmp(req->q.manpath, req->p[0]))
                printf("%s/", req->q.manpath);
        if (req->q.arch != NULL)
                printf("%s/", req->q.arch);
        http_encode(name);
        if (req->q.sec != NULL) {
                putchar('.');
                http_encode(req->q.sec);
        }
        printf("\r\nContent-Type: text/html; charset=utf-8\r\n\r\n");
}

static void
pg_searchres(const struct req *req, struct manpage *r, size_t sz)
{
        char            *arch, *archend;
        const char      *sec;
        size_t           i, iuse;
        int              archprio, archpriouse;
        int              prio, priouse;
        int              have_header;

        for (i = 0; i < sz; i++) {
                if (validate_filename(r[i].file))
                        continue;
                warnx("invalid filename %s in %s database",
                    r[i].file, req->q.manpath);
                pg_error_internal();
                return;
        }

        if (req->isquery && sz == 1) {
                /*
                 * If we have just one result, then jump there now
                 * without any delay.
                 */
                printf("Status: 303 See Other\r\n"
                    "Location: /");
                if (*scriptname != '\0')
                        printf("%s/", scriptname);
                if (strcmp(req->q.manpath, req->p[0]))
                        printf("%s/", req->q.manpath);
                printf("%s\r\n"
                    "Content-Type: text/html; charset=utf-8\r\n\r\n",
                    r[0].file);
                return;
        }

        /*
         * In man(1) mode, show one of the pages
         * even if more than one is found.
         */

        iuse = 0;
        if (req->q.equal || sz == 1) {
                priouse = 20;
                archpriouse = 3;
                for (i = 0; i < sz; i++) {
                        sec = r[i].file;
                        sec += strcspn(sec, "123456789");
                        if (sec[0] == '\0')
                                continue;
                        prio = sec_prios[sec[0] - '1'];
                        if (sec[1] != '/')
                                prio += 10;
                        if (req->q.arch == NULL) {
                                archprio =
                                    ((arch = strchr(sec + 1, '/'))
                                        == NULL) ? 3 :
                                    ((archend = strchr(arch + 1, '/'))
                                        == NULL) ? 0 :
                                    strncmp(arch, "amd64/",
                                        archend - arch) ? 2 : 1;
                                if (archprio < archpriouse) {
                                        archpriouse = archprio;
                                        priouse = prio;
                                        iuse = i;
                                        continue;
                                }
                                if (archprio > archpriouse)
                                        continue;
                        }
                        if (prio >= priouse)
                                continue;
                        priouse = prio;
                        iuse = i;
                }
                have_header = resp_begin_html(200, NULL, r[iuse].file);
        } else
                have_header = resp_begin_html(200, NULL, NULL);

        if (have_header == 0)
                puts("<header>");
        resp_searchform(req,
            req->q.equal || sz == 1 ? FOCUS_NONE : FOCUS_QUERY);
        puts("</header>");

        if (sz > 1) {
                puts("<nav>");
                puts("<table class=\"results\">");
                for (i = 0; i < sz; i++) {
                        printf("  <tr>\n"
                               "    <td>"
                               "<a class=\"Xr\" href=\"/");
                        if (*scriptname != '\0')
                                printf("%s/", scriptname);
                        if (strcmp(req->q.manpath, req->p[0]))
                                printf("%s/", req->q.manpath);
                        printf("%s\">", r[i].file);
                        html_print(r[i].names);
                        printf("</a></td>\n"
                               "    <td><span class=\"Nd\">");
                        html_print(r[i].output);
                        puts("</span></td>\n"
                             "  </tr>");
                }
                puts("</table>");
                puts("</nav>");
        }

        if (req->q.equal || sz == 1) {
                puts("<hr>");
                resp_show(req, r[iuse].file);
        }

        resp_end_html();
}

static void
resp_catman(const struct req *req, const char *file)
{
        FILE            *f;
        char            *p;
        size_t           sz;
        ssize_t          len;
        int              i;
        int              italic, bold;

        if ((f = fopen(file, "r")) == NULL) {
                puts("<p role=\"doc-notice\">\n"
                     "  You specified an invalid manual file.\n"
                     "</p>");
                return;
        }

        puts("<div class=\"catman\">\n"
             "<pre>");

        p = NULL;
        sz = 0;

        while ((len = getline(&p, &sz, f)) != -1) {
                bold = italic = 0;
                for (i = 0; i < len - 1; i++) {
                        /*
                         * This means that the catpage is out of state.
                         * Ignore it and keep going (although the
                         * catpage is bogus).
                         */

                        if ('\b' == p[i] || '\n' == p[i])
                                continue;

                        /*
                         * Print a regular character.
                         * Close out any bold/italic scopes.
                         * If we're in back-space mode, make sure we'll
                         * have something to enter when we backspace.
                         */

                        if ('\b' != p[i + 1]) {
                                if (italic)
                                        printf("</i>");
                                if (bold)
                                        printf("</b>");
                                italic = bold = 0;
                                html_putchar(p[i]);
                                continue;
                        } else if (i + 2 >= len)
                                continue;

                        /* Italic mode. */

                        if ('_' == p[i]) {
                                if (bold)
                                        printf("</b>");
                                if ( ! italic)
                                        printf("<i>");
                                bold = 0;
                                italic = 1;
                                i += 2;
                                html_putchar(p[i]);
                                continue;
                        }

                        /*
                         * Handle funny behaviour troff-isms.
                         * These grok'd from the original man2html.c.
                         */

                        if (('+' == p[i] && 'o' == p[i + 2]) ||
                                        ('o' == p[i] && '+' == p[i + 2]) ||
                                        ('|' == p[i] && '=' == p[i + 2]) ||
                                        ('=' == p[i] && '|' == p[i + 2]) ||
                                        ('*' == p[i] && '=' == p[i + 2]) ||
                                        ('=' == p[i] && '*' == p[i + 2]) ||
                                        ('*' == p[i] && '|' == p[i + 2]) ||
                                        ('|' == p[i] && '*' == p[i + 2]))  {
                                if (italic)
                                        printf("</i>");
                                if (bold)
                                        printf("</b>");
                                italic = bold = 0;
                                putchar('*');
                                i += 2;
                                continue;
                        } else if (('|' == p[i] && '-' == p[i + 2]) ||
                                        ('-' == p[i] && '|' == p[i + 1]) ||
                                        ('+' == p[i] && '-' == p[i + 1]) ||
                                        ('-' == p[i] && '+' == p[i + 1]) ||
                                        ('+' == p[i] && '|' == p[i + 1]) ||
                                        ('|' == p[i] && '+' == p[i + 1]))  {
                                if (italic)
                                        printf("</i>");
                                if (bold)
                                        printf("</b>");
                                italic = bold = 0;
                                putchar('+');
                                i += 2;
                                continue;
                        }

                        /* Bold mode. */

                        if (italic)
                                printf("</i>");
                        if ( ! bold)
                                printf("<b>");
                        bold = 1;
                        italic = 0;
                        i += 2;
                        html_putchar(p[i]);
                }

                /*
                 * Clean up the last character.
                 * We can get to a newline; don't print that.
                 */

                if (italic)
                        printf("</i>");
                if (bold)
                        printf("</b>");

                if (i == len - 1 && p[i] != '\n')
                        html_putchar(p[i]);

                putchar('\n');
        }
        free(p);

        puts("</pre>\n"
             "</div>");

        fclose(f);
}

static void
resp_format(const struct req *req, const char *file)
{
        struct manoutput conf;
        struct mparse   *mp;
        struct roff_meta *meta;
        void            *vp;
        int              fd;
        int              usepath;

        if (-1 == (fd = open(file, O_RDONLY))) {
                puts("<p role=\"doc-notice\">\n"
                     "  You specified an invalid manual file.\n"
                     "</p>");
                return;
        }

        mchars_alloc();
        mp = mparse_alloc(MPARSE_SO | MPARSE_UTF8 | MPARSE_LATIN1 |
            MPARSE_VALIDATE, MANDOC_OS_OTHER, req->q.manpath);
        mparse_readfd(mp, fd, file);
        close(fd);
        meta = mparse_result(mp);

        memset(&conf, 0, sizeof(conf));
        conf.fragment = 1;
        conf.style = mandoc_strdup(CSS_DIR "/mandoc.css");
        usepath = strcmp(req->q.manpath, req->p[0]);
        mandoc_asprintf(&conf.man, "/%s%s%s%s%%N.%%S",
            scriptname, *scriptname == '\0' ? "" : "/",
            usepath ? req->q.manpath : "", usepath ? "/" : "");

        vp = html_alloc(&conf);
        if (meta->macroset == MACROSET_MDOC)
                html_mdoc(vp, meta);
        else
                html_man(vp, meta);

        html_free(vp);
        mparse_free(mp);
        mchars_free();
        free(conf.man);
        free(conf.style);
}

static void
resp_show(const struct req *req, const char *file)
{

        if ('.' == file[0] && '/' == file[1])
                file += 2;

        if ('c' == *file)
                resp_catman(req, file);
        else
                resp_format(req, file);
}

static void
pg_show(struct req *req, const char *fullpath)
{
        char            *manpath;
        const char      *file;

        if ((file = strchr(fullpath, '/')) == NULL) {
                pg_error_badrequest(
                    "You did not specify a page to show.");
                return;
        }
        manpath = mandoc_strndup(fullpath, file - fullpath);
        file++;

        if ( ! validate_manpath(req, manpath)) {
                pg_error_badrequest(
                    "You specified an invalid manpath.");
                free(manpath);
                return;
        }

        /*
         * Begin by chdir()ing into the manpath.
         * This way we can pick up the database files, which are
         * relative to the manpath root.
         */

        if (chdir(manpath) == -1) {
                warn("chdir %s", manpath);
                pg_error_internal();
                free(manpath);
                return;
        }
        free(manpath);

        if ( ! validate_filename(file)) {
                pg_error_badrequest(
                    "You specified an invalid manual file.");
                return;
        }

        if (resp_begin_html(200, NULL, file) == 0)
                puts("<header>");
        resp_searchform(req, FOCUS_NONE);
        puts("</header>");
        resp_show(req, file);
        resp_end_html();
}

static void
pg_search(const struct req *req)
{
        struct mansearch          search;
        struct manpaths           paths;
        struct manpage           *res;
        char                    **argv;
        char                     *query, *rp, *wp;
        size_t                    ressz;
        int                       argc;

        /*
         * Begin by chdir()ing into the root of the manpath.
         * This way we can pick up the database files, which are
         * relative to the manpath root.
         */

        if (chdir(req->q.manpath) == -1) {
                warn("chdir %s", req->q.manpath);
                pg_error_internal();
                return;
        }

        search.arch = req->q.arch;
        search.sec = req->q.sec;
        search.outkey = "Nd";
        search.argmode = req->q.equal ? ARG_NAME : ARG_EXPR;
        search.firstmatch = 1;

        paths.sz = 1;
        paths.paths = mandoc_malloc(sizeof(char *));
        paths.paths[0] = mandoc_strdup(".");

        /*
         * Break apart at spaces with backslash-escaping.
         */

        argc = 0;
        argv = NULL;
        rp = query = mandoc_strdup(req->q.query);
        for (;;) {
                while (isspace((unsigned char)*rp))
                        rp++;
                if (*rp == '\0')
                        break;
                argv = mandoc_reallocarray(argv, argc + 1, sizeof(char *));
                argv[argc++] = wp = rp;
                for (;;) {
                        if (isspace((unsigned char)*rp)) {
                                *wp = '\0';
                                rp++;
                                break;
                        }
                        if (rp[0] == '\\' && rp[1] != '\0')
                                rp++;
                        if (wp != rp)
                                *wp = *rp;
                        if (*rp == '\0')
                                break;
                        wp++;
                        rp++;
                }
        }

        res = NULL;
        ressz = 0;
        if (req->isquery && req->q.equal && argc == 1)
                pg_redirect(req, argv[0]);
        else if (mansearch(&search, &paths, argc, argv, &res, &ressz) == 0)
                pg_noresult(req, 400, "Bad Request",
                    "You entered an invalid query.");
        else if (ressz == 0)
                pg_noresult(req, 404, "Not Found", "No results found.");
        else
                pg_searchres(req, res, ressz);

        free(query);
        mansearch_free(res, ressz);
        free(paths.paths[0]);
        free(paths.paths);
}

int
main(void)
{
        struct req       req;
        struct itimerval itimer;
        const char      *path;
        const char      *querystring;
        int              i;

        /*
         * The "rpath" pledge could be revoked after mparse_readfd()
         * if the file descriptor to "/footer.html" would be opened
         * up front, but it's probably not worth the complication
         * of the code it would cause: it would require scattering
         * pledge() calls in multiple low-level resp_*() functions.
         */

        if (pledge("stdio rpath", NULL) == -1) {
                warn("pledge");
                pg_error_internal();
                return EXIT_FAILURE;
        }

        /* Poor man's ReDoS mitigation. */

        itimer.it_value.tv_sec = 2;
        itimer.it_value.tv_usec = 0;
        itimer.it_interval.tv_sec = 2;
        itimer.it_interval.tv_usec = 0;
        if (setitimer(ITIMER_VIRTUAL, &itimer, NULL) == -1) {
                warn("setitimer");
                pg_error_internal();
                return EXIT_FAILURE;
        }

        /*
         * First we change directory into the MAN_DIR so that
         * subsequent scanning for manpath directories is rooted
         * relative to the same position.
         */

        if (chdir(MAN_DIR) == -1) {
                warn("MAN_DIR: %s", MAN_DIR);
                pg_error_internal();
                return EXIT_FAILURE;
        }

        memset(&req, 0, sizeof(struct req));
        req.q.equal = 1;
        parse_manpath_conf(&req);

        /* Parse the path info and the query string. */

        if ((path = getenv("PATH_INFO")) == NULL)
                path = "";
        else if (*path == '/')
                path++;

        if (*path != '\0') {
                parse_path_info(&req, path);
                if (req.q.manpath == NULL || req.q.sec == NULL ||
                    *req.q.query == '\0' || access(path, F_OK) == -1)
                        path = "";
        } else if ((querystring = getenv("QUERY_STRING")) != NULL)
                parse_query_string(&req, querystring);

        /* Validate parsed data and add defaults. */

        if (req.q.manpath == NULL)
                req.q.manpath = mandoc_strdup(req.p[0]);
        else if ( ! validate_manpath(&req, req.q.manpath)) {
                pg_error_badrequest(
                    "You specified an invalid manpath.");
                return EXIT_FAILURE;
        }

        if (req.q.arch != NULL && validate_arch(req.q.arch) == 0) {
                pg_error_badrequest(
                    "You specified an invalid architecture.");
                return EXIT_FAILURE;
        }

        /* Dispatch to the three different pages. */

        if ('\0' != *path)
                pg_show(&req, path);
        else if (NULL != req.q.query)
                pg_search(&req);
        else
                pg_index(&req);

        free(req.q.manpath);
        free(req.q.arch);
        free(req.q.sec);
        free(req.q.query);
        for (i = 0; i < (int)req.psz; i++)
                free(req.p[i]);
        free(req.p);
        return EXIT_SUCCESS;
}

/*
 * Translate PATH_INFO to a query.
 */
static void
parse_path_info(struct req *req, const char *path)
{
        const char      *name, *sec, *end;

        req->isquery = 0;
        req->q.equal = 1;
        req->q.manpath = NULL;
        req->q.arch = NULL;

        /* Mandatory manual page name. */
        if ((name = strrchr(path, '/')) == NULL)
                name = path;
        else
                name++;

        /* Optional trailing section. */
        sec = strrchr(name, '.');
        if (sec != NULL && isdigit((unsigned char)*++sec)) {
                req->q.query = mandoc_strndup(name, sec - name - 1);
                req->q.sec = mandoc_strdup(sec);
        } else {
                req->q.query = mandoc_strdup(name);
                req->q.sec = NULL;
        }

        /* Handle the case of name[.section] only. */
        if (name == path)
                return;

        /* Optional manpath. */
        end = strchr(path, '/');
        req->q.manpath = mandoc_strndup(path, end - path);
        if (validate_manpath(req, req->q.manpath)) {
                path = end + 1;
                if (name == path)
                        return;
        } else {
                free(req->q.manpath);
                req->q.manpath = NULL;
        }

        /* Optional section. */
        if (strncmp(path, "man", 3) == 0 || strncmp(path, "cat", 3) == 0) {
                path += 3;
                end = strchr(path, '/');
                free(req->q.sec);
                req->q.sec = mandoc_strndup(path, end - path);
                path = end + 1;
                if (name == path)
                        return;
        }

        /* Optional architecture. */
        end = strchr(path, '/');
        if (end + 1 != name) {
                pg_error_badrequest(
                    "You specified too many directory components.");
                exit(EXIT_FAILURE);
        }
        req->q.arch = mandoc_strndup(path, end - path);
        if (validate_arch(req->q.arch) == 0) {
                pg_error_badrequest(
                    "You specified an invalid directory component.");
                exit(EXIT_FAILURE);
        }
}

/*
 * Scan for indexable paths.
 */
static void
parse_manpath_conf(struct req *req)
{
        FILE    *fp;
        char    *dp;
        size_t   dpsz;
        ssize_t  len;

        if ((fp = fopen("manpath.conf", "r")) == NULL) {
                warn("%s/manpath.conf", MAN_DIR);
                pg_error_internal();
                exit(EXIT_FAILURE);
        }

        dp = NULL;
        dpsz = 0;

        while ((len = getline(&dp, &dpsz, fp)) != -1) {
                if (dp[len - 1] == '\n')
                        dp[--len] = '\0';
                req->p = mandoc_realloc(req->p,
                    (req->psz + 1) * sizeof(char *));
                if ( ! validate_urifrag(dp)) {
                        warnx("%s/manpath.conf contains "
                            "unsafe path \"%s\"", MAN_DIR, dp);
                        pg_error_internal();
                        exit(EXIT_FAILURE);
                }
                if (strchr(dp, '/') != NULL) {
                        warnx("%s/manpath.conf contains "
                            "path with slash \"%s\"", MAN_DIR, dp);
                        pg_error_internal();
                        exit(EXIT_FAILURE);
                }
                req->p[req->psz++] = dp;
                dp = NULL;
                dpsz = 0;
        }
        free(dp);

        if (req->p == NULL) {
                warnx("%s/manpath.conf is empty", MAN_DIR);
                pg_error_internal();
                exit(EXIT_FAILURE);
        }
}