rpki-client don't hang on rrdp hash errors

[Claudio Jeker]

When an rrdp request fails because the hash of a delta or snapshot is
incorrect the repo never finishes because the setting of
RRDP_STATE_PARSE_DONE and the call to rrdp_finished() is skipped.
The result is a hanging rpki-client until the alarm kills it after 1h.

This simple diff should fix the issue.  Added extra contex to make it more
obvious why this return is bad.
-- 
:wq Claudio

Index: rrdp.c
===================================================================
RCS file: /cvs/src/usr.sbin/rpki-client/rrdp.c,v
retrieving revision 1.1
diff -u -p -U14 -r1.1 rrdp.c
--- rrdp.c      1 Apr 2021 16:04:48 -0000       1.1
+++ rrdp.c      6 Apr 2021 16:00:14 -0000
@@ -474,29 +474,28 @@ rrdp_data_handler(struct rrdp *s)
        if ((s->state & RRDP_STATE_PARSE) == 0)
                errx(1, "%s: bad parser state", s->local);
        if (len == 0) {
                /* parser stage finished */
                close(s->infd);
                s->infd = -1;
 
                if (s->task != NOTIFICATION) {
                        char h[SHA256_DIGEST_LENGTH];
 
                        SHA256_Final(h, &s->ctx);
                        if (memcmp(s->hash, h, sizeof(s->hash)) != 0) {
                                s->state |= RRDP_STATE_PARSE_ERROR;
                                warnx("%s: bad message digest", s->local);
-                               return;
                        }
                }
 
                s->state |= RRDP_STATE_PARSE_DONE;
                rrdp_finished(s);
                return;
        }
 
        /* parse and maybe hash the bytes just read */
        if (s->task != NOTIFICATION)
                SHA256_Update(&s->ctx, buf, len);
        if ((s->state & RRDP_STATE_PARSE_ERROR) == 0 &&
            XML_Parse(p, buf, len, 0) != XML_STATUS_OK) {
                s->state |= RRDP_STATE_PARSE_ERROR;