--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/pircharge/interf.c	Tue Dec 19 02:58:38 2017 +0000
@@ -0,0 +1,103 @@
+/*
+ * This module implements the link to rvinterf.
+ */
+
+#include <sys/types.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include <rvinterf/localsock.h>
+#include <rvinterf/exitcodes.h>
+
+extern int sock;
+
+u_char rvi_msg[LOCALSOCK_MAX_MSG];
+int rvi_msg_len;
+
+static int rx_state, rx_left;
+static u_char *rx_ptr;
+
+void
+localsock_prep_for_length_rx()
+{
+	rx_state = 0;
+	rx_ptr = rvi_msg;
+	rx_left = 2;
+}
+
+static void
+prep_for_message_rx()
+{
+	rx_state = 1;
+	rx_ptr = rvi_msg;
+	rx_left = rvi_msg_len;
+}
+
+void
+process_msg_from_rvinterf()
+{
+	switch (rvi_msg[0]) {
+	case RVI2CLI_PKT_FROM_TARGET:
+		process_pkt_from_target();
+		return;
+	case RVI2CLI_LOCAL_CMD_RESP:
+		if (rvi_msg_len < 2)
+			goto bad;
+		if (rvi_msg[1] == '+')
+			return;
+		fprintf(stderr, "Error from rvinterf: %.*s\n", rvi_msg_len - 1,
+			rvi_msg + 1);
+		exit(ERROR_RVINTERF);
+	default:
+	bad:
+		fprintf(stderr,
+			"Error: unexpected message type %02X from rvinterf\n",
+			rvi_msg[0]);
+		exit(ERROR_RVINTERF);
+	}
+}
+
+void
+handle_rvinterf_input()
+{
+	int cc;
+
+	cc = read(sock, rx_ptr, rx_left);
+	if (cc <= 0) {
+		perror("read from rvinterf socket");
+		exit(ERROR_RVINTERF);
+	}
+	rx_ptr += cc;
+	rx_left -= cc;
+	if (rx_left)
+		return;
+	/* got the thing, process it */
+	if (rx_state) {
+		process_msg_from_rvinterf();
+		localsock_prep_for_length_rx();
+	} else {
+		rvi_msg_len = rvi_msg[0] << 8 | rvi_msg[1];
+		if (rvi_msg_len < 1 || rvi_msg_len > LOCALSOCK_MAX_MSG) {
+			fprintf(stderr,
+				"Invalid length from rvinterf: %02X%02X\n",
+				rvi_msg[0], rvi_msg[1]);
+			exit(ERROR_RVINTERF);
+		}
+		prep_for_message_rx();
+	}
+}
+
+void
+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(sock, hdrbuf, 3);
+	write(sock, pkt, pktlen);
+}