--- a/autocal/rvinterf.c	Sun May 21 23:00:32 2017 +0000
+++ b/autocal/rvinterf.c	Sun May 21 23:04:42 2017 +0000
@@ -12,11 +12,16 @@
 #include <unistd.h>
 #include <rvinterf/pktmux.h>
 #include <rvinterf/localsock.h>
+#include <rvinterf/limits.h>
 #include <rvinterf/exitcodes.h>
 
 char *rvif_socket_pathname = "/tmp/rvinterf_socket";
 int rvif_socket;
 
+int rx_enable_state;
+u_char rvi_msg[LOCALSOCK_MAX_MSG];
+int rvi_msg_len;
+
 connect_rvinterf_socket()
 {
 	/* local socket binding voodoo copied from osmocon */
@@ -54,3 +59,107 @@
 
 	return(0);
 }
+
+static void
+collect_bytes_from_rvi(buf, nbytes)
+	u_char *buf;
+{
+	int cc;
+
+	while (nbytes) {
+		cc = read(rvif_socket, buf, nbytes);
+		if (cc <= 0) {
+			perror("read from rvinterf socket");
+			exit(ERROR_RVINTERF);
+		}
+		buf += cc;
+		nbytes -= cc;
+	}
+}
+
+collect_rvi_msg()
+{
+	u_char lenbuf[2];
+
+	collect_bytes_from_rvi(lenbuf, 2);
+	rvi_msg_len = lenbuf[0] << 8 | lenbuf[1];
+	if (rvi_msg_len < 1 || rvi_msg_len > LOCALSOCK_MAX_MSG) {
+		fprintf(stderr, "Invalid length from rvinterf: %02X%02X\n",
+			lenbuf[0], lenbuf[1]);
+		exit(ERROR_RVINTERF);
+	}
+	collect_bytes_from_rvi(rvi_msg, rvi_msg_len);
+	return(0);
+}
+
+send_rvimisc_command(cmdpkt, cmdlen)
+	u_char *cmdpkt;
+{
+	u_char lenbuf[2];
+
+	lenbuf[0] = 0;
+	lenbuf[1] = cmdlen;
+	write(rvif_socket, lenbuf, 2);
+	write(rvif_socket, cmdpkt, cmdlen);
+}
+
+rx_control(enable)
+{
+	u_char cmdpkt[2];
+	int cmdlen;
+
+	/* are we already in the desired state? */
+	if (rx_enable_state == enable)
+		return(0);
+	/* no, do the work */
+	if (enable) {
+		cmdpkt[0] = CLI2RVI_WANT_MUXPROTO;
+		cmdpkt[1] = RVT_TM_HEADER;
+		cmdlen = 2;
+	} else {
+		cmdpkt[0] = CLI2RVI_RESET_PACKET_RX;
+		cmdlen = 1;
+	}
+	send_rvimisc_command(cmdpkt, cmdlen);
+	collect_rvi_msg();
+	if (rvi_msg[0] != RVI2CLI_LOCAL_CMD_RESP || rvi_msg_len < 2) {
+		fprintf(stderr,
+		"error: unexpected response to rvinterf local command\n");
+		exit(ERROR_RVINTERF);
+	}
+	if (rvi_msg[1] != '+') {
+		fprintf(stderr, "Error from rvinterf: %.*s\n", rvi_msg_len - 1,
+			rvi_msg + 1);
+		exit(ERROR_RVINTERF);
+	}
+	rx_enable_state = enable;
+	return(0);
+}
+
+send_pkt_to_target(pkt, pktlen)
+	u_char *pkt;
+{
+	u_char hdrbuf[3];
+	int len1;
+
+	len1 = pktlen + 1;
+	hdrbuf[0] = len1 >> 8;
+	hdrbuf[1] = len1 & 0xFF;
+	hdrbuf[2] = CLI2RVI_PKT_TO_TARGET;
+	write(rvif_socket, hdrbuf, 3);
+	write(rvif_socket, pkt, pktlen);
+}
+
+target_pkt_exch(outpkt, outpktlen)
+	u_char *outpkt;
+{
+	rx_control(1);
+	send_pkt_to_target(outpkt, outpktlen);
+	collect_rvi_msg();
+	if (rvi_msg[0] != RVI2CLI_PKT_FROM_TARGET) {
+		fprintf(stderr,
+			"error: unexpected response type from rvinterf\n");
+		exit(ERROR_RVINTERF);
+	}
+	return(0);
+}