- if ((!ctl->sslproto || !strcmp(ctl->sslproto,"tls1"))
- && !ctl->use_ssl
- && strstr(capabilities, "STARTTLS"))
- {
- char *realhost;
-
- realhost = ctl->server.via ? ctl->server.via : ctl->server.pollname;
- ok = gen_transact(sock, "STARTTLS");
-
- /* We use "tls1" instead of ctl->sslproto, as we want STARTTLS,
- * not other SSL protocols
- */
- if (ok == PS_SUCCESS &&
- SSLOpen(sock,ctl->sslcert,ctl->sslkey,"tls1",ctl->sslcertck, ctl->sslcertpath,ctl->sslfingerprint,realhost,ctl->server.pollname) == -1)
- {
- if (!ctl->sslproto && !ctl->wehaveauthed)
- {
- ctl->sslproto = xstrdup("");
- /* repoll immediately */
- return(PS_REPOLL);
- }
- report(stderr,
- GT_("SSL connection failed.\n"));
- return PS_SOCKET;
- }
- did_stls = TRUE;
-
- /*
- * RFC 2595 says this:
- *
- * "Once TLS has been started, the client MUST discard cached
- * information about server capabilities and SHOULD re-issue the
- * CAPABILITY command. This is necessary to protect against
- * man-in-the-middle attacks which alter the capabilities list prior
- * to STARTTLS. The server MAY advertise different capabilities
- * after STARTTLS."
- */
- capa_probe(sock, ctl);
+ realhost = ctl->server.via ? ctl->server.via : ctl->server.pollname;
+
+ if (maybe_tls(ctl)) {
+ if (strstr(capabilities, "STARTTLS"))
+ {
+ /* Use "tls1" rather than ctl->sslproto because tls1 is the only
+ * protocol that will work with STARTTLS. Don't need to worry
+ * whether TLS is mandatory or opportunistic unless SSLOpen() fails
+ * (see below). */
+ if (gen_transact(sock, "STARTTLS") == PS_SUCCESS
+ && SSLOpen(sock, ctl->sslcert, ctl->sslkey, "tls1", ctl->sslcertck,
+ ctl->sslcertpath, ctl->sslfingerprint, realhost,
+ ctl->server.pollname, &ctl->remotename) != -1)
+ {
+ /*
+ * RFC 2595 says this:
+ *
+ * "Once TLS has been started, the client MUST discard cached
+ * information about server capabilities and SHOULD re-issue the
+ * CAPABILITY command. This is necessary to protect against
+ * man-in-the-middle attacks which alter the capabilities list prior
+ * to STARTTLS. The server MAY advertise different capabilities
+ * after STARTTLS."
+ *
+ * Now that we're confident in our TLS connection we can
+ * guarantee a secure capability re-probe.
+ */
+ got_tls = 1;
+ capa_probe(sock, ctl);
+ if (outlevel >= O_VERBOSE)
+ {
+ report(stdout, GT_("%s: upgrade to TLS succeeded.\n"), realhost);
+ }
+ }
+ }
+
+ if (!got_tls) {
+ if (must_tls(ctl)) {
+ /* Config required TLS but we couldn't guarantee it, so we must
+ * stop. */
+ report(stderr, GT_("%s: upgrade to TLS failed.\n"), realhost);
+ return PS_SOCKET;
+ } else {
+ if (outlevel >= O_VERBOSE) {
+ report(stdout, GT_("%s: opportunistic upgrade to TLS failed, trying to continue\n"), realhost);
+ }
+ /* We don't know whether the connection is in a working state, so
+ * test by issuing a NOOP. */
+ if (gen_transact(sock, "NOOP") != PS_SUCCESS) {
+ /* Not usable. Empty sslproto to force an unencrypted
+ * connection on the next attempt, and repoll. */
+ ctl->sslproto = xstrdup("");
+ return PS_REPOLL;
+ }
+ /* Usable. Proceed with authenticating insecurely. */
+ }
+ }