From 8c27290245b7bcc7cd2f72f3b4a7562294b43bbe Mon Sep 17 00:00:00 2001
From: David Härdeman <david@hardeman.nu>
Date: Tue, 23 Jun 2020 16:25:36 +0200
Subject: Split directories better

---
 shared/rcon-protocol.c | 185 +++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 185 insertions(+)
 create mode 100644 shared/rcon-protocol.c

(limited to 'shared/rcon-protocol.c')

diff --git a/shared/rcon-protocol.c b/shared/rcon-protocol.c
new file mode 100644
index 0000000..0ea1245
--- /dev/null
+++ b/shared/rcon-protocol.c
@@ -0,0 +1,185 @@
+#include <stdint.h>
+#include <stdbool.h>
+#include <stddef.h>
+#include <string.h>
+
+#include "rcon-protocol.h"
+
+static int32_t
+read_int(const char **pos, size_t *len)
+{
+	uint32_t val;
+	const char *p;
+
+	if (!pos || !*pos)
+		return 0;
+
+	if (len && *len < RCON_INT_LEN)
+		return 0;
+
+	p = *pos;
+	val  = ((uint8_t)p[0] <<  0);
+	val += ((uint8_t)p[1] <<  8);
+	val += ((uint8_t)p[2] << 16);
+	val += ((uint8_t)p[3] << 24);
+
+	*pos += RCON_INT_LEN;
+	if (len)
+		*len -= RCON_INT_LEN;
+
+	return (int32_t)val;
+}
+
+static void
+write_int(char **pos, size_t *len, int32_t orig)
+{
+	uint32_t val = (uint32_t)orig;
+	char *p;
+
+	if (!pos || !*pos)
+		return;
+
+	p = *pos;
+	p[0] = (val >>  0) & 0xff;
+	p[1] = (val >>  8) & 0xff;
+	p[2] = (val >> 16) & 0xff;
+	p[3] = (val >> 24) & 0xff;
+
+	*pos += RCON_INT_LEN;
+	if (len)
+		*len += RCON_INT_LEN;
+}
+
+static void
+write_str(char **pos, size_t *len, const char *str, size_t slen)
+{
+	if (!pos || !*pos || !str || *str == '\0' || slen < 1)
+		return;
+
+	memcpy(*pos, str, slen);
+	*pos += slen;
+	if (len)
+		*len += slen;
+}
+
+static void
+write_end(char **pos, size_t *len)
+{
+	char *p;
+
+	if (!pos || !*pos)
+		return;
+
+	p = *pos;
+	p[0] = 0x00;
+	p[1] = 0x00;
+
+	*pos += RCON_END_LEN;
+	if (len)
+		*len += RCON_END_LEN;
+}
+
+bool
+rcon_protocol_create_packet(char *buf, size_t len, size_t *rlen, int32_t reqid,
+			    enum rcon_packet_type type, const char *msg)
+{
+	size_t plen, msglen;
+	char *pos;
+
+	if (!buf || !rlen || !msg || msg[0] == '\0')
+		return false;
+
+	msglen = strlen(msg);
+	if (len < rcon_protocol_packet_len(msglen))
+		return false;
+
+	/* Body */
+	pos = buf + RCON_HDR_LEN;
+	plen = RCON_HDR_LEN;
+	write_int(&pos, &plen, reqid);
+	write_int(&pos, &plen, type);
+	write_str(&pos, &plen, msg, msglen);
+	write_end(&pos, &plen);
+
+	/* Header (length of body) */
+	pos = buf;
+	write_int(&pos, NULL, plen - RCON_HDR_LEN);
+
+	*rlen = plen;
+	return true;
+}
+
+/*
+ * Returns:
+ * < 0 = error
+ *   0 = packet not complete
+ * > 0 = packet complete (length)
+ */
+int32_t
+rcon_protocol_packet_complete(const char *buf, size_t len)
+{
+	const char *pos;
+	int32_t plen;
+
+	if (!buf)
+		return -1;
+
+	if (len < RCON_PKT_MIN_LEN)
+		return 0;
+
+	pos = buf;
+	plen = read_int(&pos, NULL) + RCON_HDR_LEN;
+
+	if (plen < RCON_HDR_LEN)
+		/* Read a negative int */
+		return -1;
+
+	if (len < plen)
+		return 0;
+	else
+		return plen;
+}
+
+bool
+rcon_protocol_read_packet(const char *buf, size_t len, int32_t *id, int32_t *type,
+			  const char **rmsg, const char **error)
+{
+	const char *pos;
+	int32_t plen;
+
+	if (!error)
+		return false;
+
+	if (!buf || !id || !type || !rmsg) {
+		*error = "invalid arguments";
+		return false;
+	}
+
+	plen = rcon_protocol_packet_complete(buf, len);
+	*error = "invalid packet length";
+	if (plen < RCON_PKT_MIN_LEN)
+		return false;
+
+	pos = buf + RCON_HDR_LEN;
+	len -= RCON_HDR_LEN;
+
+	*id = read_int(&pos, &len);
+	*type = read_int(&pos, &len);
+	*rmsg = NULL;
+
+	if (len < RCON_END_LEN)
+		return false;
+	else if (len > RCON_END_LEN) {
+		*rmsg = pos;
+		pos += len - RCON_END_LEN;
+		len = RCON_END_LEN;
+	}
+
+	if (pos[0] != '\0' || pos[1] != '\0') {
+		*error = "invalid trailer";
+		return false;
+	}
+
+	*error = NULL;
+	return true;
+}
-- 
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