wireshark/epan/dissectors/packet-logcat.c

/* packet-logcat.c
 * Routines for Android Logcat binary format v1 and v2
 *
 * Copyright 2014, Michal Labedzki for Tieto Corporation
 *
 * Wireshark - Network traffic analyzer
 * By Gerald Combs <gerald@wireshark.org>
 * Copyright 1998 Gerald Combs
 *
 * SPDX-License-Identifier: GPL-2.0-or-later
 */

#include "config.h"

#include <epan/packet.h>
#include <epan/expert.h>
#include <epan/exported_pdu.h>
#include <epan/tap.h>
#include <epan/prefs.h>
#include <wiretap/wtap.h>

static int proto_logcat = -1;

static int hf_logcat_version = -1;
static int hf_logcat_length = -1;
static int hf_logcat_padding = -1;
static int hf_logcat_header_size = -1;
static int hf_logcat_pid = -1;
static int hf_logcat_tid = -1;
static int hf_logcat_timestamp = -1;
static int hf_logcat_timestamp_seconds = -1;
static int hf_logcat_timestamp_nanoseconds = -1;
static int hf_logcat_euid = -1;
static int hf_logcat_priority = -1;
static int hf_logcat_tag = -1;
static int hf_logcat_log = -1;

static gint ett_logcat = -1;
static gint ett_logcat_timestamp = -1;
static gint ett_logcat_log = -1;

static dissector_handle_t logcat_handle;
static dissector_handle_t data_text_lines_handle;

static gint exported_pdu_tap = -1;

static expert_field ei_invalid_payload_length = EI_INIT;

static gboolean  pref_one_line_info_column = TRUE;

const value_string priority_vals[] = {
    { 0x00,  "Unknown" },
    { 0x01,  "Default" },
    { 0x02,  "Verbose" },
    { 0x03,  "Debug" },
    { 0x04,  "Info" },
    { 0x05,  "Warning" },
    { 0x06,  "Error" },
    { 0x07,  "Fatal" },
    { 0x08,  "Silent" },
    { 0, NULL }
};

void proto_register_logcat(void);
void proto_reg_handoff_logcat(void);

static gint detect_version(tvbuff_t *tvb, gint offset) {
    guint16         payload_length;
    guint16         try_header_size;

    payload_length  = tvb_get_letohs(tvb, offset);
    try_header_size = tvb_get_letohs(tvb, offset + 2);

    if (try_header_size != 24)
        return 1;

    if (tvb_reported_length_remaining(tvb, offset + 24 + payload_length) >= 0)
        return 2;

    return 1;
}

static int
dissect_logcat(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, void *data _U_)
{
    gint         offset = 0;
    proto_tree  *maintree;
    proto_item  *mainitem;
    proto_tree  *subtree;
    proto_item  *subitem;
    guint16      length;
    guint16      check_length;
    guint32      string_length;
    gint         logger_version;
    guint8      *log;
    gchar       *c;
    tvbuff_t    *next_tvb;

    col_set_str(pinfo->cinfo, COL_PROTOCOL, "Logcat");
    col_clear(pinfo->cinfo, COL_INFO);

    mainitem = proto_tree_add_item(tree, proto_logcat, tvb, offset, -1, ENC_NA);
    maintree = proto_item_add_subtree(mainitem, ett_logcat);

    logger_version = detect_version(tvb, offset);

    subitem = proto_tree_add_uint(maintree, hf_logcat_version, tvb, offset, 0, logger_version);
    proto_item_set_generated(subitem);

    proto_tree_add_item(maintree, hf_logcat_length, tvb, offset, 2, ENC_LITTLE_ENDIAN);
    length = tvb_get_letohs(tvb, offset);
    offset += 2;

    if (logger_version == 1) {
        proto_tree_add_item(maintree, hf_logcat_padding, tvb, offset, 2, ENC_LITTLE_ENDIAN);
    } else {
        proto_tree_add_item(maintree, hf_logcat_header_size, tvb, offset, 2, ENC_LITTLE_ENDIAN);
    }
    offset += 2;

    proto_tree_add_item(maintree, hf_logcat_pid, tvb, offset, 4, ENC_LITTLE_ENDIAN);
    offset += 4;

    proto_tree_add_item(maintree, hf_logcat_tid, tvb, offset, 4, ENC_LITTLE_ENDIAN);
    offset += 4;

    subitem = proto_tree_add_item(maintree, hf_logcat_timestamp, tvb, offset, 8, ENC_LITTLE_ENDIAN);
    subtree = proto_item_add_subtree(subitem, ett_logcat_timestamp);

    proto_tree_add_item(subtree, hf_logcat_timestamp_seconds, tvb, offset, 4, ENC_LITTLE_ENDIAN);
    offset += 4;

    proto_tree_add_item(subtree, hf_logcat_timestamp_nanoseconds, tvb, offset, 4, ENC_LITTLE_ENDIAN);
    offset += 4;

    if (logger_version >= 2) {
        proto_tree_add_item(maintree, hf_logcat_euid, tvb, offset, 4, ENC_LITTLE_ENDIAN);
        offset += 4;
    }

    /* payload */
    proto_tree_add_item(maintree, hf_logcat_priority, tvb, offset, 1, ENC_LITTLE_ENDIAN);
    offset += 1;
    check_length = 1;

    string_length = tvb_strsize(tvb, offset);
    proto_tree_add_item(maintree, hf_logcat_tag, tvb, offset, string_length, ENC_UTF_8 | ENC_NA);

    set_address_tvb(&pinfo->src, AT_STRINGZ, string_length + 1, tvb, offset);
    set_address(&pinfo->dst, AT_STRINGZ, 7, "Logcat");

    offset += string_length;
    check_length += string_length;

    string_length = length - string_length - 1;
    log = tvb_get_string_enc(pinfo->pool, tvb, offset, string_length, ENC_UTF_8);

    /* New line characters convert to spaces to ensure column Info display one line */
    if (pref_one_line_info_column) {
        while ((c = g_utf8_strchr(log, string_length, '\n')))
            *c = ' ';
        while ((c = g_utf8_strchr(log, string_length, '\r')))
            *c = ' ';
    }

    subitem = proto_tree_add_item(maintree, hf_logcat_log, tvb, offset, string_length, ENC_UTF_8 | ENC_NA);
    subtree = proto_item_add_subtree(subitem, ett_logcat_log);

    next_tvb = tvb_new_subset_length(tvb, offset, string_length - 1);
    call_dissector(data_text_lines_handle, next_tvb, pinfo, subtree);

    col_add_str(pinfo->cinfo, COL_INFO, log);
    offset += string_length;
    check_length += string_length;

    if (length != check_length)
        proto_tree_add_expert(maintree, pinfo, &ei_invalid_payload_length, tvb, offset, tvb_reported_length_remaining(tvb, offset));

    if (have_tap_listener(exported_pdu_tap)) {

        exp_pdu_data_t *exp_pdu_data = export_pdu_create_tags(pinfo, "logcat", EXP_PDU_TAG_DISSECTOR_NAME, NULL);

        exp_pdu_data->tvb_captured_length = tvb_captured_length(tvb);
        exp_pdu_data->tvb_reported_length = tvb_reported_length(tvb);
        exp_pdu_data->pdu_tvb = tvb;
        tap_queue_packet(exported_pdu_tap, pinfo, exp_pdu_data);
    }

    return offset;
}

void
proto_register_logcat(void)
{
    module_t         *module;
    expert_module_t  *expert_module;
    static hf_register_info hf[] = {
        { &hf_logcat_version,
            { "Logger Version",                  "logcat.logger_version",
            FT_UINT8, BASE_DEC, NULL, 0x00,
            NULL, HFILL }
        },
        { &hf_logcat_length,
            { "Payload Length",                  "logcat.length",
            FT_UINT16, BASE_DEC, NULL, 0x00,
            "Payload start after nanoseconds or euid", HFILL }
        },
        { &hf_logcat_padding,
            { "Padding",                         "logcat.padding",
            FT_UINT16, BASE_HEX, NULL, 0x00,
            "No matter what, we get 2 bytes of padding", HFILL }
        },
        { &hf_logcat_header_size,
            { "Header Size",                     "logcat.header_size",
            FT_UINT16, BASE_HEX, NULL, 0x00,
            "Size of struct logger_entry_v2", HFILL }
        },
        { &hf_logcat_pid,
            { "PID",                             "logcat.pid",
            FT_INT32, BASE_DEC, NULL, 0x00,
            "Process ID", HFILL }
        },
        { &hf_logcat_tid,
            { "TID",                             "logcat.tid",
            FT_INT32, BASE_DEC, NULL, 0x00,
            "Thread ID", HFILL }
        },
        { &hf_logcat_timestamp,
            { "Timestamp",                       "logcat.timestamp",
            FT_ABSOLUTE_TIME, ABSOLUTE_TIME_LOCAL, NULL, 0x00,
            NULL, HFILL }
        },
        { &hf_logcat_timestamp_seconds,
            { "Timestamp in seconds",            "logcat.timestamp.seconds",
            FT_INT32, BASE_DEC, NULL, 0x00,
            NULL, HFILL }
        },
        { &hf_logcat_timestamp_nanoseconds,
            { "Nanoseconds Timestamp",           "logcat.timestamp.nanoseconds",
            FT_INT32, BASE_DEC, NULL, 0x00,
            NULL, HFILL }
        },
        { &hf_logcat_euid,
            { "EUID",                            "logcat.euid",
            FT_UINT32, BASE_DEC, NULL, 0x00,
            "Effective UID of logger", HFILL }
        },
        { &hf_logcat_priority,
            { "Priority",                        "logcat.priority",
            FT_UINT8, BASE_DEC, VALS(priority_vals), 0x00,
            NULL, HFILL }
        },
        { &hf_logcat_tag,
            { "Tag",                             "logcat.tag",
            FT_STRINGZ, BASE_NONE, NULL, 0x00,
            NULL, HFILL }
        },
        { &hf_logcat_log,
            { "Log",                             "logcat.log",
            FT_STRINGZ, BASE_NONE, NULL, 0x00,
            NULL, HFILL }
        }
    };

    static gint *ett[] = {
        &ett_logcat,
        &ett_logcat_timestamp,
        &ett_logcat_log
    };

    static ei_register_info ei[] = {
        { &ei_invalid_payload_length, { "logcat.expert.invalid_payload_length", PI_PROTOCOL, PI_WARN, "Payload length does not meet sum of payload data length", EXPFILL }},
    };

    proto_logcat = proto_register_protocol("Android Logcat", "Logcat", "logcat");
    proto_register_field_array(proto_logcat, hf, array_length(hf));
    proto_register_subtree_array(ett, array_length(ett));
    logcat_handle = register_dissector("logcat", dissect_logcat, proto_logcat);

    expert_module = expert_register_protocol(proto_logcat);
    expert_register_field_array(expert_module, ei, array_length(ei));

    exported_pdu_tap = register_export_pdu_tap("Logcat");

    module = prefs_register_protocol(proto_logcat, NULL);
    prefs_register_bool_preference(module, "oneline_info_column",
            "Use oneline info column",
            "Use oneline info column by replace all new line characters by spaces",
            &pref_one_line_info_column);
}


void
proto_reg_handoff_logcat(void)
{
    data_text_lines_handle = find_dissector_add_dependency("data-text-lines", proto_logcat);

    dissector_add_uint("wtap_encap", WTAP_ENCAP_LOGCAT, logcat_handle);

    dissector_add_for_decode_as_with_preference("tcp.port", logcat_handle);
}

/*
 * Editor modelines  -  https://www.wireshark.org/tools/modelines.html
 *
 * Local variables:
 * c-basic-offset: 4
 * tab-width: 8
 * indent-tabs-mode: nil
 * End:
 *
 * vi: set shiftwidth=4 tabstop=8 expandtab:
 * :indentSize=4:tabSize=8:noTabs=true:
 */