path: root/epan/dissectors/packet-sap.c

/* packet-sap.c
 * Routines for sap packet dissection
 * RFC 2974
 *
 * Heikki Vatiainen <hessu@cs.tut.fi>
 *
 * Wireshark - Network traffic analyzer
 * By Gerald Combs <gerald@wireshark.org>
 * Copyright 1998 Gerald Combs
 *
 * Copied from packet-tftp.c
 *
 * SPDX-License-Identifier: GPL-2.0-or-later
 */

#include "config.h"

#include <epan/packet.h>
#include <epan/expert.h>

#define UDP_PORT_SAP   9875

#define MCAST_SAP_VERSION_MASK 0xE0 /* 3 bits for  SAP version*/
#define MCAST_SAP_VERSION_SHIFT 5   /* Right shift 5 bits to get the version */
#define MCAST_SAP_VER0 0            /* Version 0 */
#define MCAST_SAP_VER1PLUS 1        /* Version 1 or later */

void proto_register_sap(void);
void proto_reg_handoff_sap(void);

static dissector_handle_t sap_handle;

static const value_string mcast_sap_ver[] = {
    { MCAST_SAP_VER0,     "SAPv0"},
    { MCAST_SAP_VER1PLUS, "SAPv1 or later"},
    { 0,                  NULL}
};

static const true_false_string mcast_sap_address_type = {"IPv6", "IPv4"};
static const true_false_string mcast_sap_message_type = { "Deletion", "Announcement"};
static const true_false_string mcast_sap_crypt_type = { "Payload encrypted", "Payload not encrypted"};
static const true_false_string mcast_sap_comp_type = { "Payload compressed", "Payload not compressed"};

static const value_string mcast_sap_auth_ver[] = {
    { 1, "SAP authentication header v1"},
    { 0,                  NULL}
};

static const true_false_string mcast_sap_auth_pad = {
    "Authentication subheader padded to 32 bits",
    "No padding required for the authentication subheader"
};

#define MCAST_SAP_AUTH_TYPE_MASK 0x0F /* 4 bits for the type of the authentication header */
#define MCAST_SAP_AUTH_TYPE_PGP 0
#define MCAST_SAP_AUTH_TYPE_CMS 1
static const value_string mcast_sap_auth_type[] = {
    { MCAST_SAP_AUTH_TYPE_PGP,  "PGP"},
    { MCAST_SAP_AUTH_TYPE_CMS,  "CMS"},
    { 0,                   NULL}
};

#define MCAST_SAP_BIT_A 0x10 /* Address type: 0 IPv4, 1 IPv6 */
#define MCAST_SAP_BIT_R 0x08 /* Reserved: Must be 0 */
#define MCAST_SAP_BIT_T 0x04 /* Message Type: 0 announcement, 1 deletion */
#define MCAST_SAP_BIT_E 0x02 /* Encryption Bit: 1 payload encrypted */
#define MCAST_SAP_BIT_C 0x01 /* Compressed Bit: 1 payload zlib compressed */

#define MCAST_SAP_AUTH_BIT_P 0x10 /* Padding required for the authentication header */


static int proto_sap;
static int hf_sap_flags;
static int hf_sap_flags_v;
static int hf_sap_flags_a;
static int hf_sap_flags_r;
static int hf_sap_flags_t;
static int hf_sap_flags_e;
static int hf_sap_flags_c;
static int hf_auth_data;
static int hf_auth_flags;
static int hf_auth_flags_v;
static int hf_auth_flags_p;
static int hf_auth_flags_t;
/* Generated from convert_proto_tree_add_text.pl */
static int hf_sap_auth_len;
static int hf_sap_originating_source_ipv4;
static int hf_sap_auth_data_padding;
static int hf_sap_auth_subheader;
static int hf_sap_originating_source_ipv6;
static int hf_sap_message_identifier_hash;
static int hf_sap_auth_data_padding_len;
static int hf_sap_payload_type;

static int ett_sap;
static int ett_sap_flags;
static int ett_sap_auth;
static int ett_sap_authf;

static expert_field ei_sap_compressed_and_encrypted;
static expert_field ei_sap_encrypted;
static expert_field ei_sap_compressed;
/* Generated from convert_proto_tree_add_text.pl */
static expert_field ei_sap_bogus_authentication_or_pad_length;

static dissector_handle_t sdp_handle;

static int
dissect_sap(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, void* data _U_)
{
    int offset = 0;
    int sap_version, is_ipv6, is_del, is_enc, is_comp, addr_len;
    uint8_t vers_flags;
    uint8_t auth_len;
    uint8_t auth_flags;
    tvbuff_t *next_tvb;

    proto_item *si, *sif;
    proto_tree *sap_tree = NULL, *sap_flags_tree;

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

    vers_flags = tvb_get_uint8(tvb, offset);
    is_ipv6 = vers_flags&MCAST_SAP_BIT_A;
    is_del = vers_flags&MCAST_SAP_BIT_T;
    is_enc = vers_flags&MCAST_SAP_BIT_E;
    is_comp = vers_flags&MCAST_SAP_BIT_C;

    sap_version = (vers_flags&MCAST_SAP_VERSION_MASK)>>MCAST_SAP_VERSION_SHIFT;
    addr_len = (is_ipv6) ? (int)sizeof(ws_in6_addr) : 4;

    col_add_fstr(pinfo->cinfo, COL_INFO, "%s (v%u)",
                            (is_del) ? "Deletion" : "Announcement", sap_version);

    if (tree) {
        si = proto_tree_add_item(tree, proto_sap, tvb, offset, -1, ENC_NA);
        sap_tree = proto_item_add_subtree(si, ett_sap);

        sif = proto_tree_add_item(sap_tree, hf_sap_flags, tvb, offset, 1, ENC_BIG_ENDIAN);
        sap_flags_tree = proto_item_add_subtree(sif, ett_sap_flags);
        proto_tree_add_item(sap_flags_tree, hf_sap_flags_v, tvb, offset, 1, ENC_BIG_ENDIAN);
        proto_tree_add_item(sap_flags_tree, hf_sap_flags_a, tvb, offset, 1, ENC_NA);
        proto_tree_add_item(sap_flags_tree, hf_sap_flags_r, tvb, offset, 1, ENC_NA);
        proto_tree_add_item(sap_flags_tree, hf_sap_flags_t, tvb, offset, 1, ENC_NA);
        proto_tree_add_item(sap_flags_tree, hf_sap_flags_e, tvb, offset, 1, ENC_NA);
        proto_tree_add_item(sap_flags_tree, hf_sap_flags_c, tvb, offset, 1, ENC_NA);
    }

    offset++;

    auth_len = tvb_get_uint8(tvb, offset);
    proto_tree_add_item(sap_tree, hf_sap_auth_len, tvb, offset, 1, ENC_BIG_ENDIAN);
    offset++;

    proto_tree_add_item(sap_tree, hf_sap_message_identifier_hash, tvb, offset, 2, ENC_BIG_ENDIAN);
    offset +=2;

    if (is_ipv6)
        proto_tree_add_item(sap_tree, hf_sap_originating_source_ipv6, tvb, offset, addr_len, ENC_NA);
    else
        proto_tree_add_item(sap_tree, hf_sap_originating_source_ipv4, tvb, offset, addr_len, ENC_BIG_ENDIAN);
    offset += addr_len;

    /* Authentication data lives in its own subtree */
    if (auth_len > 0) {
        uint32_t auth_data_len;
        proto_item *sdi, *sai;
        proto_tree *sa_tree, *saf_tree;
        int has_pad;
        uint8_t pad_len = 0;

        auth_data_len = (uint32_t)(auth_len * sizeof(uint32_t));

        sdi = proto_tree_add_item(sap_tree, hf_auth_data, tvb, offset, auth_data_len, ENC_NA);
        sa_tree = proto_item_add_subtree(sdi, ett_sap_auth);

        auth_flags = tvb_get_uint8(tvb, offset);
        sai = proto_tree_add_item(sa_tree, hf_auth_flags, tvb, offset, 1, ENC_BIG_ENDIAN);
        saf_tree = proto_item_add_subtree(sai, ett_sap_authf);
        proto_tree_add_item(saf_tree, hf_auth_flags_v, tvb, offset, 1, ENC_BIG_ENDIAN);
        proto_tree_add_item(saf_tree, hf_auth_flags_p, tvb, offset, 1, ENC_NA);
        proto_tree_add_item(saf_tree, hf_auth_flags_t, tvb, offset, 1, ENC_BIG_ENDIAN);

        has_pad = auth_flags&MCAST_SAP_AUTH_BIT_P;
        if (has_pad) {
            pad_len = tvb_get_uint8(tvb, offset+auth_data_len-1);
        }

        if ((int) auth_data_len - pad_len - 1 < 0) {
            expert_add_info_format(pinfo, sai, &ei_sap_bogus_authentication_or_pad_length,
                                        "Bogus authentication length (%d) or pad length (%d)", auth_len, pad_len);
            return tvb_captured_length(tvb);
        }


        proto_tree_add_item(sa_tree, hf_sap_auth_subheader, tvb, offset+1, auth_data_len-pad_len-1, ENC_NA);
        if (has_pad) {
            proto_tree_add_item(sa_tree, hf_sap_auth_data_padding_len, tvb, offset+auth_data_len-1, 1, ENC_BIG_ENDIAN);
            proto_tree_add_item(sa_tree, hf_sap_auth_data_padding, tvb, offset+auth_data_len-pad_len, pad_len, ENC_NA);
        }

        offset += auth_data_len;
    }

    if (is_enc || is_comp) {
        expert_field *mangle;
        if (is_enc && is_comp)
            mangle = &ei_sap_compressed_and_encrypted;
        else if (is_enc)
            mangle = &ei_sap_encrypted;
        else
            mangle = &ei_sap_compressed;

        proto_tree_add_expert(sap_tree, pinfo, mangle, tvb, offset, -1);
        return tvb_captured_length(tvb);
    }

    if (tree) {
        /* Do we have the optional payload type aka. MIME content specifier */
        if (tvb_strneql(tvb, offset, "v=", strlen("v="))) {
            int remaining_len;
            uint32_t pt_len;
            int pt_string_len;
            uint8_t* pt_str;

            remaining_len = tvb_captured_length_remaining(tvb, offset);
            if (remaining_len == 0) {
                /*
                    * "tvb_strneql()" failed because there was no
                    * data left in the packet.
                    *
                    * Set the remaining length to 1, so that
                    * we throw the appropriate exception in
                    * "tvb_get_ptr()", rather than displaying
                    * the payload type.
                    */
                remaining_len = 1;
            }

            pt_string_len = tvb_strnlen(tvb, offset, remaining_len);
            if (pt_string_len == -1) {
                /*
                 * We didn't find a terminating '\0'; run to the
                 * end of the buffer.
                 */
                pt_string_len = remaining_len;
                pt_len = pt_string_len;
            } else {
                /*
                 * Include the '\0' in the total item length.
                 */
                pt_len = pt_string_len + 1;
            }

            pt_str = tvb_get_string_enc(pinfo->pool, tvb, offset, pt_string_len, ENC_ASCII);
            proto_tree_add_string_format_value(sap_tree, hf_sap_payload_type, tvb, offset, pt_len,
                pt_str, "%s", pt_str);
            offset += pt_len;
        }
    }

    /* Done with SAP */
    next_tvb = tvb_new_subset_remaining(tvb, offset);
    call_dissector(sdp_handle, next_tvb, pinfo, tree);
    return tvb_captured_length(tvb);
}

void proto_register_sap(void)
{

    static hf_register_info hf[] = {
    { &hf_sap_flags,
        { "Flags",         "sap.flags",
        FT_UINT8, BASE_HEX, NULL, 0x0,
        "Bits in the beginning of the SAP header", HFILL }},

    { &hf_sap_flags_v,
        { "Version Number",         "sap.flags.v",
        FT_UINT8, BASE_DEC, VALS(mcast_sap_ver), MCAST_SAP_VERSION_MASK,
        "3 bit version field in the SAP header", HFILL }},

    { &hf_sap_flags_a,
        { "Address Type",           "sap.flags.a",
        FT_BOOLEAN, 8, TFS(&mcast_sap_address_type), MCAST_SAP_BIT_A,
        "Originating source address type", HFILL }},

    { &hf_sap_flags_r,
        { "Reserved",               "sap.flags.r",
        FT_BOOLEAN, 8, TFS(&tfs_set_notset), MCAST_SAP_BIT_R,
        NULL, HFILL }},

    { &hf_sap_flags_t,
        { "Message Type",           "sap.flags.t",
        FT_BOOLEAN, 8, TFS(&mcast_sap_message_type), MCAST_SAP_BIT_T,
        "Announcement type", HFILL }},

    { &hf_sap_flags_e,
        { "Encryption Bit",         "sap.flags.e",
        FT_BOOLEAN, 8, TFS(&mcast_sap_crypt_type), MCAST_SAP_BIT_E,
        NULL, HFILL }},

    { &hf_sap_flags_c,
        { "Compression Bit",         "sap.flags.c",
        FT_BOOLEAN, 8, TFS(&mcast_sap_comp_type), MCAST_SAP_BIT_C,
        NULL, HFILL }},

    { &hf_auth_data,
        { "Authentication data",     "sap.auth",
        FT_NONE, BASE_NONE, NULL, 0x0,
        NULL, HFILL }},

    { &hf_auth_flags,
        { "Authentication data flags", "sap.auth.flags",
        FT_UINT8, BASE_HEX, NULL, 0x0,
        NULL, HFILL }},

    { &hf_auth_flags_v,
        { "Version Number",         "sap.auth.flags.v",
        FT_UINT8, BASE_DEC, VALS(mcast_sap_auth_ver), MCAST_SAP_VERSION_MASK,
        NULL, HFILL }},

    { &hf_auth_flags_p,
        { "Padding Bit",            "sap.auth.flags.p",
        FT_BOOLEAN, 8, TFS(&mcast_sap_auth_pad), MCAST_SAP_AUTH_BIT_P,
        NULL, HFILL }},

    { &hf_auth_flags_t,
        { "Authentication Type",         "sap.auth.flags.t",
        FT_UINT8, BASE_DEC, VALS(mcast_sap_auth_type), MCAST_SAP_AUTH_TYPE_MASK,
        NULL, HFILL }},

        /* Generated from convert_proto_tree_add_text.pl */
        { &hf_sap_auth_len, { "Authentication Length", "sap.auth.len", FT_UINT8, BASE_DEC, NULL, 0x0, NULL, HFILL }},
        { &hf_sap_message_identifier_hash, { "Message Identifier Hash", "sap.message_identifier_hash", FT_UINT16, BASE_HEX, NULL, 0x0, NULL, HFILL }},
        { &hf_sap_originating_source_ipv4, { "Originating Source", "sap.originating_source", FT_IPv4, BASE_NONE, NULL, 0x0, NULL, HFILL }},
        { &hf_sap_originating_source_ipv6, { "Originating Source", "sap.originating_source.ipv6", FT_IPv6, BASE_NONE, NULL, 0x0, NULL, HFILL }},
        { &hf_sap_auth_subheader, { "Authentication subheader", "sap.auth.subheader", FT_BYTES, BASE_NONE, NULL, 0x0, NULL, HFILL }},
        { &hf_sap_auth_data_padding, { "Authentication data padding", "sap.auth.data_padding", FT_BYTES, BASE_NONE, NULL, 0x0, NULL, HFILL }},
        { &hf_sap_auth_data_padding_len, { "Authentication data pad count (bytes)", "sap.auth.data_padding.len", FT_UINT8, BASE_DEC, NULL, 0x0, NULL, HFILL }},
        { &hf_sap_payload_type, { "Payload type", "sap.payload_type", FT_STRING, BASE_NONE, NULL, 0x0, NULL, HFILL }},

    };
    static int *ett[] = {
        &ett_sap,
        &ett_sap_flags,
        &ett_sap_auth,
        &ett_sap_authf,
    };

    static ei_register_info ei[] = {
        { &ei_sap_compressed_and_encrypted, { "sap.compressed_and_encrypted", PI_UNDECODED, PI_WARN, "The rest of the packet is compressed and encrypted", EXPFILL }},
        { &ei_sap_encrypted, { "sap.encrypted", PI_UNDECODED, PI_WARN, "The rest of the packet is encrypted", EXPFILL }},
        { &ei_sap_compressed, { "sap.compressed", PI_UNDECODED, PI_WARN, "The rest of the packet is compressed", EXPFILL }},

        /* Generated from convert_proto_tree_add_text.pl */
        { &ei_sap_bogus_authentication_or_pad_length, { "sap.bogus_authentication_or_pad_length", PI_PROTOCOL, PI_WARN, "Bogus authentication length", EXPFILL }},
    };

    expert_module_t* expert_sap;

    proto_sap = proto_register_protocol("Session Announcement Protocol", "SAP", "sap");

    proto_register_field_array(proto_sap, hf, array_length(hf));
    proto_register_subtree_array(ett, array_length(ett));
    expert_sap = expert_register_protocol(proto_sap);
    expert_register_field_array(expert_sap, ei, array_length(ei));

    sap_handle = register_dissector("sap", dissect_sap, proto_sap);
}

void
proto_reg_handoff_sap(void)
{
    dissector_add_uint_with_preference("udp.port", UDP_PORT_SAP, sap_handle);

    /*
     * Get a handle for the SDP dissector.
     */
    sdp_handle = find_dissector_add_dependency("sdp", proto_sap);
}

/*
 * 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:
 */