kd.c

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// SPDX-FileCopyrightText: 2014-2017 LemonBoy <thatlemon@gmail.com>
// SPDX-License-Identifier: LGPL-3.0-only
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include "kd.h"
#include <rz_util/rz_log.h>
 
#define KD_DBG if (false)
 
ut32 kd_data_checksum(const ut8 *buf, const ut64 buf_len) {
    ut32 i, acc;
 
    if (!buf || !buf_len) {
        return 0;
    }
 
    for (i = acc = 0; i < buf_len; i++) {
        acc += buf[i];
    }
 
    return acc;
}
 
int kd_send_ctrl_packet(io_desc_t *desc, const ut32 type, const ut32 id) {
    kd_packet_t pkt;
 
    pkt.leader = KD_PACKET_CTRL;
    pkt.length = 0;
    pkt.checksum = 0;
    pkt.id = id;
    pkt.type = type;
 
    if (iob_write(desc, (ut8 *)&pkt, sizeof(kd_packet_t)) < 0) {
        return KD_E_IOERR;
    }
 
    return KD_E_OK;
}
 
int kd_send_data_packet(io_desc_t *desc, const ut32 type, const ut32 id, const ut8 *req,
    const int req_len, const ut8 *buf, const ut32 buf_len) {
    kd_packet_t pkt;
 
    if (req_len + buf_len > KD_MAX_PAYLOAD) {
        return KD_E_MALFORMED;
    }
 
    RZ_LOG_DEBUG("==== Send Data ====\n");
    RZ_LOG_DEBUG("ID: 0x%" PFMT32x "\n", id);
    RZ_LOG_DEBUG("Type: 0x%" PFMT32x "\n", type);
 
    pkt.leader = KD_PACKET_DATA;
    pkt.length = req_len + buf_len;
    pkt.checksum = kd_data_checksum(req, req_len) + kd_data_checksum(buf, buf_len);
    pkt.id = id;
    pkt.type = type;
 
    if (iob_write(desc, (ut8 *)&pkt, sizeof(kd_packet_t)) < 0) {
        return KD_E_IOERR;
    }
 
    if (iob_write(desc, (ut8 *)req, req_len) < 0) {
        return KD_E_IOERR;
    }
 
    if (buf && iob_write(desc, (ut8 *)buf, buf_len) < 0) {
        return KD_E_IOERR;
    }
 
    if (desc->iob->type == KD_IO_PIPE) {
        if (iob_write(desc, (ut8 *)"\xAA", 1) < 0) {
            return KD_E_IOERR;
        }
    }
 
    return KD_E_OK;
}
 
int kd_read_packet(io_desc_t *desc, kd_packet_t **p) {
    kd_packet_t pkt;
    ut8 *buf;
 
    *p = NULL;
 
    if (iob_read(desc, (ut8 *)&pkt, sizeof(kd_packet_t)) <= 0) {
        return KD_E_IOERR;
    }
 
    if (!kd_packet_is_valid(&pkt)) {
        KD_DBG eprintf("invalid leader %08x, trying to recover\n", pkt.leader);
        while (!kd_packet_is_valid(&pkt)) {
            kd_send_ctrl_packet(desc, KD_PACKET_TYPE_RESEND, 0);
            char sig[4];
            // Read byte-by-byte searching for the start of a packet
            int ret;
            while ((ret = iob_read(desc, (ut8 *)&sig, 1)) > 0) {
                if (sig[0] == '0' || sig[0] == 'i') {
                    if (iob_read(desc, (ut8 *)&sig + 1, 3) == 3) {
                        if (strncmp(sig, "000", 3) && strncmp(sig, "iii", 3)) {
                            continue;
                        }
                        memcpy(&pkt, sig, sizeof(sig));
                        if (iob_read(desc, (ut8 *)&pkt + 4, sizeof(kd_packet_t) - 4) <= 0) {
                            return KD_E_IOERR;
                        }
                        break;
                    } else {
                        return KD_E_IOERR;
                    }
                }
            }
            if (!ret) {
                return KD_E_IOERR;
            }
        }
    }
 
    buf = malloc(sizeof(kd_packet_t) + pkt.length);
    if (!buf) {
        return KD_E_IOERR;
    }
    memcpy(buf, &pkt, sizeof(kd_packet_t));
 
    if (pkt.length) {
        iob_read(desc, (ut8 *)buf + sizeof(kd_packet_t), pkt.length);
    }
 
    if (pkt.checksum != kd_data_checksum(buf + sizeof(kd_packet_t), pkt.length)) {
        KD_DBG eprintf("Checksum mismatch!\n");
        free(buf);
        return KD_E_MALFORMED;
    }
 
    if (pkt.leader == KD_PACKET_DATA) {
        if (desc->iob->type == KD_IO_PIPE) {
            ut8 trailer;
            iob_read(desc, (ut8 *)&trailer, 1);
 
            if (trailer != 0xAA) {
                KD_DBG eprintf("Missing trailer 0xAA\n");
                free(buf);
                return KD_E_MALFORMED;
            }
        }
    }
    kd_send_ctrl_packet(desc, KD_PACKET_TYPE_ACKNOWLEDGE, pkt.id);
 
    *p = (kd_packet_t *)buf;
 
    return KD_E_OK;
}
 
bool kd_packet_is_valid(const kd_packet_t *p) {
    return p->leader == KD_PACKET_CTRL || p->leader == KD_PACKET_DATA || p->leader == KD_PACKET_UNUSED;
}
 
int kd_packet_is_ack(const kd_packet_t *p) {
    return p->leader == KD_PACKET_CTRL && p->type == KD_PACKET_TYPE_ACKNOWLEDGE;
}