Subversion Repositories planix.SVN

/*
 * for GET or POST to /magic/save/foo.
 * add incoming data to foo.data.
 * send foo.html as reply.
 *
 * supports foo.data with "exclusive use" mode to prevent interleaved saves.
 * thus http://cm.bell-labs.com/magic/save/t?args should access:
 * -lrw-rw--w- M 21470 ehg web 1533 May 21 18:19 /usr/web/save/t.data
 * --rw-rw-r-- M 21470 ehg web   73 May 21 18:17 /usr/web/save/t.html
*/
#include <u.h>
#include <libc.h>
#include <bio.h>
#include "httpd.h"
#include "httpsrv.h"

enum
{
        MaxLog          = 24*1024,              /* limit on length of any one log request */
        LockSecs        = MaxLog/500,           /* seconds to wait before giving up on opening the data file */
};

static int
dangerous(char *s)
{
        if(s == nil)
                return 1;

        /*
         * This check shouldn't be needed;
         * filename folding is already supposed to have happened.
         * But I'm paranoid.
         */
        while(s = strchr(s,'/')){
                if(s[1]=='.' && s[2]=='.')
                        return 1;
                s++;
        }
        return 0;
}

/*
 * open a file which might be locked.
 * if it is, spin until available
 */
int
openLocked(char *file, int mode)
{
        char buf[ERRMAX];
        int tries, fd;

        for(tries = 0; tries < LockSecs*2; tries++){
                fd = open(file, mode);
                if(fd >= 0)
                        return fd;
                errstr(buf, sizeof buf);
                if(strstr(buf, "locked") == nil)
                        break;
                sleep(500);
        }
        return -1;
}

void
main(int argc, char **argv)
{
        HConnect *c;
        Dir *dir;
        Hio *hin, *hout;
        char *s, *t, *fn;
        int n, nfn, datafd, htmlfd;

        c = init(argc, argv);

        if(dangerous(c->req.uri)){
                hfail(c, HSyntax);
                exits("failed");
        }

        if(hparseheaders(c, HSTIMEOUT) < 0)
                exits("failed");
        hout = &c->hout;
        if(c->head.expectother){
                hfail(c, HExpectFail, nil);
                exits("failed");
        }
        if(c->head.expectcont){
                hprint(hout, "100 Continue\r\n");
                hprint(hout, "\r\n");
                hflush(hout);
        }

        s = nil;
        if(strcmp(c->req.meth, "POST") == 0){
                hin = hbodypush(&c->hin, c->head.contlen, c->head.transenc);
                if(hin != nil){
                        alarm(HSTIMEOUT);
                        s = hreadbuf(hin, hin->pos);
                        alarm(0);
                }
                if(s == nil){
                        hfail(c, HBadReq, nil);
                        exits("failed");
                }
                t = strchr(s, '\n');
                if(t != nil)
                        *t = '\0';
        }else if(strcmp(c->req.meth, "GET") != 0 && strcmp(c->req.meth, "HEAD") != 0){
                hunallowed(c, "GET, HEAD, PUT");
                exits("unallowed");
        }else
                s = c->req.search;
        if(s == nil){
                hfail(c, HNoData, "save");
                exits("failed");
        }

        if(strlen(s) > MaxLog)
                s[MaxLog] = '\0';
        n = snprint(c->xferbuf, HBufSize, "at %ld %s\n", time(0), s);


        nfn = strlen(c->req.uri) + 64;
        fn = halloc(c, nfn);

        /*
         * open file descriptors & write log line
         */
        snprint(fn, nfn, "/usr/web/save/%s.html", c->req.uri);
        htmlfd = open(fn, OREAD);
        if(htmlfd < 0 || (dir = dirfstat(htmlfd)) == nil){
                hfail(c, HNotFound, c->req.uri);
                exits("failed");
                return;
        }

        snprint(fn, nfn, "/usr/web/save/%s.data", c->req.uri);
        datafd = openLocked(fn, OWRITE);
        if(datafd < 0){
                errstr(c->xferbuf, sizeof c->xferbuf);
                if(strstr(c->xferbuf, "locked") != nil)
                        hfail(c, HTempFail, c->req.uri);
                else
                        hfail(c, HNotFound, c->req.uri);
                exits("failed");
        }
        seek(datafd, 0, 2);
        write(datafd, c->xferbuf, n);
        close(datafd);

        sendfd(c, htmlfd, dir, hmkcontent(c, "text", "html", nil), nil);

        exits(nil);
}