#include <ctype.h>

#include <u.h>
#include <libc.h>
#include <ctype.h>
#include <bio.h>
#include <regexp.h>
#include <fcall.h>
#include "httpd.h"
#include "httpsrv.h"

static Hio *hout;
static Hio houtb;
static HConnect *connect;
static int vermaj, gidwidth, uidwidth, lenwidth, devwidth;
static Biobuf *aio, *dio;

static void
doctype(void)
{
hprint(hout, "<!DOCTYPE html PUBLIC \"-//W3C//DTD XHTML 1.0 Transitional//EN\"\n");
hprint(hout, " \"http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd\">\n");
}

void
error(char *title, char *fmt, ...)
{
va_list arg;
char buf[1024], *out;

va_start(arg, fmt);
out = vseprint(buf, buf+sizeof(buf), fmt, arg);
va_end(arg);
*out = 0;

hprint(hout, "%s 404 %s\r\n", hversion, title);
hprint(hout, "Date: %D\r\n", time(nil));
hprint(hout, "Server: Plan9\r\n");
hprint(hout, "Content-type: text/html\r\n");
hprint(hout, "\r\n");
doctype();
hprint(hout, "<html xmlns=\"http://www.w3.org/1999/xhtml\">\n");
hprint(hout, "<head><title>%s</title></head>\n", title);
hprint(hout, "<body>\n");
hprint(hout, "<h1>%s</h1>\n", title);
hprint(hout, "%s\n", buf);
hprint(hout, "</body>\n");
hprint(hout, "</html>\n");
hflush(hout);
writelog(connect, "Reply: 404\nReason: %s\n", title);
exits(nil);
}

/*
* Are we actually allowed to look in here?
*
* Rules:
* 1) If neither allowed nor denied files exist, access is granted.
* 2) If allowed exists and denied does not, dir *must* be in allowed
* for access to be granted, otherwise, access is denied.
* 3) If denied exists and allowed does not, dir *must not* be in
* denied for access to be granted, otherwise, access is enied.
* 4) If both exist, okay if either (a) file is not in denied, or
* (b) in denied and in allowed. Otherwise, access is denied.
*/
static Reprog *
getre(Biobuf *buf)
{
Reprog *re;
char *p, *t;
char *bbuf;
int n;

if (buf == nil)
return(nil);
for ( ; ; free(p)) {
p = Brdstr(buf, '\n', 0);
if (p == nil)
return(nil);
t = strchr(p, '#');
if (t != nil)
*t = '\0';
t = p + strlen(p);
while (--t > p && isspace(*t))
*t = '\0';
n = strlen(p);
if (n == 0)
continue;

/* root the regular expresssion */
bbuf = malloc(n+2);
if(bbuf == nil)
sysfatal("out of memory");
bbuf[0] = '^';
strcpy(bbuf+1, p);
re = regcomp(bbuf);
free(bbuf);

if (re == nil)
continue;
free(p);
return(re);
}
}

static int
allowed(char *dir)
{
Reprog *re;
int okay;
Resub match;

if (strcmp(dir, "..") == 0 || strncmp(dir, "../", 3) == 0)
return(0);
if (aio == nil)
return(0);

if (aio != nil)
Bseek(aio, 0, 0);
if (dio != nil)
Bseek(dio, 0, 0);

/* if no deny list, assume everything is denied */
okay = (dio != nil);

/* go through denials till we find a match */
while (okay && (re = getre(dio)) != nil) {
memset(&match, 0, sizeof(match));
okay = (regexec(re, dir, &match, 1) != 1);
free(re);
}

/* go through accepts till we have a match */
if (aio == nil)
return(okay);
while (!okay && (re = getre(aio)) != nil) {
memset(&match, 0, sizeof(match));
okay = (regexec(re, dir, &match, 1) == 1);
free(re);
}
return(okay);
}

/*
* Comparison routine for sorting the directory.
*/
static int
compar(Dir *a, Dir *b)
{
return(strcmp(a->name, b->name));
}

/*
* These is for formating; how wide are variable-length
* fields?
*/
static void
maxwidths(Dir *dp, long n)
{
long i;
char scratch[64];

for (i = 0; i < n; i++) {
if (snprint(scratch, sizeof scratch, "%ud", dp[i].dev) > devwidth)
devwidth = strlen(scratch);
if (strlen(dp[i].uid) > uidwidth)
uidwidth = strlen(dp[i].uid);
if (strlen(dp[i].gid) > gidwidth)
gidwidth = strlen(dp[i].gid);
if (snprint(scratch, sizeof scratch, "%lld", dp[i].length) > lenwidth)
lenwidth = strlen(scratch);
}
}

/*
* Do an actual directory listing.
* asciitime is lifted directly out of ls.
*/
char *
asciitime(long l)
{
ulong clk;
static char buf[32];
char *t;

clk = time(nil);
t = ctime(l);
/* 6 months in the past or a day in the future */
if(l<clk-180L*24*60*60 || clk+24L*60*60<l){
memmove(buf, t+4, 7); /* month and day */
memmove(buf+7, t+23, 5); /* year */
}else
memmove(buf, t+4, 12); /* skip day of week */
buf[12] = 0;
return buf;
}

static void
dols(char *dir)
{
Dir *d;
char *f, *p,*nm;
long i, n;
int fd;

cleanname(dir); // expands "" to "."; ``dir+1'' access below depends on that
if (!allowed(dir)) {
error("Permission denied", "<p>Cannot list directory %s: Access prohibited</p>", dir);
return;
}
fd = open(dir, OREAD);
if (fd < 0) {
error("Cannot read directory", "<p>Cannot read directory %s: %r</p>", dir);
return;
}
if (vermaj) {
hokheaders(connect);
hprint(hout, "Content-type: text/html\r\n");
hprint(hout, "\r\n");
}
doctype();
hprint(hout, "<html xmlns=\"http://www.w3.org/1999/xhtml\">\n");
hprint(hout, "<head><title>Index of %s</title></head>\n", dir);
hprint(hout, "<body>\n");
hprint(hout, "<h1>Index of ");
nm = dir;
while((p = strchr(nm, '/')) != nil){
*p = '\0';
f = (*dir == '\0') ? "/" : dir;
if (!(*dir == '\0' && *(dir+1) == '\0') && allowed(f))
hprint(hout, "<a href=\"/magic/webls?dir=%H\">%s/</a>", f, nm);
else
hprint(hout, "%s/", nm);
*p = '/';
nm = p+1;
}
hprint(hout, "%s</h1>\n", nm);
n = dirreadall(fd, &d);
close(fd);
maxwidths(d, n);
qsort(d, n, sizeof(Dir), (int (*)(void *, void *))compar);
hprint(hout, "<pre>\n");
for (i = 0; i < n; i++) {
f = smprint("%s/%s", dir, d[i].name);
cleanname(f);
if (d[i].mode & DMDIR) {
p = smprint("/magic/webls?dir=%H", f);
free(f);
f = p;
}
hprint(hout, "%M %C %*ud %-*s %-*s %*lld %s <a href=\"%s\">%s</a>\n",
d[i].mode, d[i].type,
devwidth, d[i].dev,
uidwidth, d[i].uid,
gidwidth, d[i].gid,
lenwidth, d[i].length,
asciitime(d[i].mtime), f, d[i].name);
free(f);
}
f = smprint("%s/..", dir);
cleanname(f);
if (strcmp(f, dir) != 0 && allowed(f))
hprint(hout, "\nGo to <a href=\"/magic/webls?dir=%H\">parent</a> directory\n", f);
else
hprint(hout, "\nEnd of directory listing\n");
free(f);
hprint(hout, "</pre>\n</body>\n</html>\n");
hflush(hout);
free(d);
}

/*
* Handle unpacking the request in the URI and
* invoking the actual handler.
*/
static void
dosearch(char *search)
{
if (strncmp(search, "dir=", 4) == 0){
search = hurlunesc(connect, search+4);
dols(search);
return;
}

/*
* Otherwise, we've gotten an illegal request.
* spit out a non-apologetic error.
*/
search = hurlunesc(connect, search);
error("Bad directory listing request",
"<p>Illegal formatted directory listing request:</p>\n"
"<p>%H</p>", search);
}

void
main(int argc, char **argv)
{
fmtinstall('H', httpfmt);
fmtinstall('U', hurlfmt);
fmtinstall('M', dirmodefmt);

aio = Bopen("/sys/lib/webls.allowed", OREAD);
dio = Bopen("/sys/lib/webls.denied", OREAD);

if(argc == 2){
hinit(&houtb, 1, Hwrite);
hout = &houtb;
dols(argv[1]);
exits(nil);
}
close(2);

connect = init(argc, argv);
hout = &connect->hout;
vermaj = connect->req.vermaj;
if(hparseheaders(connect, HSTIMEOUT) < 0)
exits("failed");

if(strcmp(connect->req.meth, "GET") != 0 && strcmp(connect->req.meth, "HEAD") != 0){
hunallowed(connect, "GET, HEAD");
exits("not allowed");
}
if(connect->head.expectother || connect->head.expectcont){
hfail(connect, HExpectFail, nil);
exits("failed");
}

bind(webroot, "/", MREPL);

if(connect->req.search != nil)
dosearch(connect->req.search);
else
error("Bad argument", "<p>Need a search argument</p>");
hflush(hout);
writelog(connect, "200 webls %ld %ld\n", hout->seek, hout->seek);
exits(nil);
}