BUG in /sys/src/libauth/getchal.c

[Vadim Antonov avg@postman.ncube.com]

Hi -- error handling in getchal/chalreply routines
was broken.  If one of file descriptors was wrong
close() overwrites error string.

The new code which produces correct error string
is appended.

--vadim

----cut here----
#include <u.h>
#include <libc.h>
#include <auth.h>
#include "authlocal.h"

static char *damsg = "problem with /dev/authenticate";
static char *ccmsg = "can't call AS";
static char *pbmsg = "AS protocol botch";

int
getchal(Chalstate *c, char *user)
{
        int n;
        Ticketreq tr;
        char trbuf[TICKREQLEN];

        /* get ticket request from kernel and add user name */
        c->afd = open("/dev/authenticate", ORDWR);
        if(c->afd < 0){
                werrstr(damsg);
                return -1;
        }
        n = read(c->afd, trbuf, TICKREQLEN);
        if(n != TICKREQLEN){
                close(c->afd);
                werrstr(damsg);
                return -1;
        }
        convM2TR(trbuf, &tr);
        memset(tr.uid, 0, sizeof(tr.uid));
        strcpy(tr.uid, user);
        tr.type = AuthChal;
        convTR2M(&tr, trbuf);

        /* send request to authentication server and get challenge */
        c->asfd = authdial();
        if(c->asfd < 0){
                close(c->afd);
                werrstr(ccmsg);
                c->afd = c->asfd = -1;
                return -1;
        }
        if(write(c->asfd, trbuf, TICKREQLEN) != TICKREQLEN){
                werrstr(pbmsg);
                goto err;
        }
        if(_asrdresp(c->asfd, c->chal, NETCHLEN) < 0)
                goto err;
        return 0;
err:
        close(c->afd);
        close(c->asfd);
        c->afd = c->asfd = -1;
        return -1;
}

int
chalreply(Chalstate *c, char *response)
{
        char resp[NETCHLEN];
        char ticket[TICKETLEN];

        /* send response to auth server and get ticket */
        memset(resp, 0, sizeof resp);
        strncpy(resp, response, NETCHLEN-1);
        if(write(c->asfd, resp, NETCHLEN) != NETCHLEN){
                werrstr(pbmsg);
                goto err;
        }
        if(_asrdresp(c->asfd, ticket, TICKETLEN+AUTHENTLEN) < 0)
                goto err;

        /* pass ticket to /dev/authenticate */
        if(write(c->afd, ticket, TICKETLEN+AUTHENTLEN) != TICKETLEN+AUTHENTLEN){
                werrstr("permission denied");
                goto err;
        }
        close(c->asfd);
        close(c->afd);
        c->afd = c->asfd = -1;
        return 0;
err:
        if(c->asfd >= 0)
                close(c->asfd);
        if(c->afd >= 0)
                close(c->afd);
        c->afd = c->asfd = -1;
        return -1;
}