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/* SPDX-License-Identifier: GPL-2.0 */
#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_verify_response(int32_t id_sent, int32_t id_recv,
enum rcon_packet_type t_sent,
enum rcon_packet_type t_recv,
const char **error)
{
if (t_sent == RCON_PACKET_LOGIN) {
if (t_recv != RCON_PACKET_LOGIN_RESPONSE) {
*error = "invalid reply id";
return false;
} else if (id_recv == RCON_PACKET_LOGIN_FAIL_ID) {
*error = "login failure";
return false;
} else if (id_recv != id_sent) {
*error = "invalid reply id";
return false;
}
} else {
if (t_recv != RCON_PACKET_RESPONSE) {
*error = "invalid reply type";
return false;
} else if (id_recv != id_sent) {
*error = "invalid reply id";
return false;
}
}
return true;
}
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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