/* packet-pgsql.c
 * Routines for PostgreSQL v3 protocol dissection.
 * <http://www.postgresql.org/docs/current/static/protocol.html>
 * Copyright 2004 Abhijit Menon-Sen <ams@oryx.com>
 *
 * 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 "packet-tls-utils.h"
#include "packet-tcp.h"

void proto_register_pgsql(void);
void proto_reg_handoff_pgsql(void);

static dissector_handle_t pgsql_handle;
static dissector_handle_t tls_handle;

static int proto_pgsql = -1;
static int hf_frontend = -1;
static int hf_type = -1;
static int hf_length = -1;
static int hf_version_major = -1;
static int hf_version_minor = -1;
static int hf_supported_minor_version = -1;
static int hf_number_nonsupported_options = -1;
static int hf_nonsupported_option = -1;
static int hf_parameter_name = -1;
static int hf_parameter_value = -1;
static int hf_query = -1;
static int hf_authtype = -1;
static int hf_passwd = -1;
static int hf_salt = -1;
static int hf_gssapi_sspi_data = -1;
static int hf_sasl_auth_mech = -1;
static int hf_sasl_auth_data = -1;
static int hf_sasl_auth_data_length = -1;
static int hf_statement = -1;
static int hf_portal = -1;
static int hf_return = -1;
static int hf_tag = -1;
static int hf_status = -1;
static int hf_copydata = -1;
static int hf_error = -1;
static int hf_pid = -1;
static int hf_key = -1;
static int hf_condition = -1;
static int hf_text = -1;
static int hf_tableoid = -1;
static int hf_typeoid = -1;
static int hf_oid = -1;
static int hf_format = -1;
static int hf_field_count = -1;
static int hf_val_name = -1;
static int hf_val_idx = -1;
static int hf_val_length = -1;
static int hf_val_data = -1;
static int hf_val_mod = -1;
static int hf_severity = -1;
static int hf_code = -1;
static int hf_message = -1;
static int hf_detail = -1;
static int hf_hint = -1;
static int hf_position = -1;
static int hf_internal_position = -1;
static int hf_internal_query = -1;
static int hf_where = -1;
static int hf_schema_name = -1;
static int hf_table_name = -1;
static int hf_column_name = -1;
static int hf_type_name = -1;
static int hf_constraint_name = -1;
static int hf_file = -1;
static int hf_line = -1;
static int hf_routine = -1;

static gint ett_pgsql = -1;
static gint ett_values = -1;

#define PGSQL_PORT 5432
static gboolean pgsql_desegment = TRUE;
static gboolean first_message = TRUE;

typedef enum {
  PGSQL_AUTH_STATE_NONE,               /*  No authentication seen or used */
  PGSQL_AUTH_SASL_REQUESTED,           /* Server sends SASL auth request with supported SASL mechanisms*/
  PGSQL_AUTH_SASL_CONTINUE,            /* Server and/or client send further SASL challange-response messages */
  PGSQL_AUTH_GSSAPI_SSPI_DATA,         /* GSSAPI/SSPI in use */
} pgsql_auth_state_t;

typedef struct pgsql_conn_data {
    gboolean    ssl_requested;
    pgsql_auth_state_t auth_state; /* Current authentication state */
} pgsql_conn_data_t;

static const value_string fe_messages[] = {
    { 'p', "Authentication message" },
    { 'Q', "Simple query" },
    { 'P', "Parse" },
    { 'B', "Bind" },
    { 'E', "Execute" },
    { 'D', "Describe" },
    { 'C', "Close" },
    { 'H', "Flush" },
    { 'S', "Sync" },
    { 'F', "Function call" },
    { 'd', "Copy data" },
    { 'c', "Copy completion" },
    { 'f', "Copy failure" },
    { 'X', "Termination" },
    { 0, NULL }
};

static const value_string be_messages[] = {
    { 'R', "Authentication request" },
    { 'K', "Backend key data" },
    { 'S', "Parameter status" },
    { '1', "Parse completion" },
    { '2', "Bind completion" },
    { '3', "Close completion" },
    { 'C', "Command completion" },
    { 't', "Parameter description" },
    { 'T', "Row description" },
    { 'D', "Data row" },
    { 'I', "Empty query" },
    { 'n', "No data" },
    { 'E', "Error" },
    { 'N', "Notice" },
    { 's', "Portal suspended" },
    { 'Z', "Ready for query" },
    { 'A', "Notification" },
    { 'V', "Function call response" },
    { 'G', "CopyIn response" },
    { 'H', "CopyOut response" },
    { 'd', "Copy data" },
    { 'c', "Copy completion" },
    { 'v', "Negotiate protocol version" },
    { 0, NULL }
};

#define PGSQL_AUTH_TYPE_SUCCESS 0
#define PGSQL_AUTH_TYPE_KERBEROS4 1
#define PGSQL_AUTH_TYPE_KERBEROS5 2
#define PGSQL_AUTH_TYPE_PLAINTEXT 3
#define PGSQL_AUTH_TYPE_CRYPT 4
#define PGSQL_AUTH_TYPE_MD5 5
#define PGSQL_AUTH_TYPE_SCM 6
#define PGSQL_AUTH_TYPE_GSSAPI 7
#define PGSQL_AUTH_TYPE_GSSAPI_SSPI_CONTINUE 8
#define PGSQL_AUTH_TYPE_SSPI 9
#define PGSQL_AUTH_TYPE_SASL 10
#define PGSQL_AUTH_TYPE_SASL_CONTINUE 11
#define PGSQL_AUTH_TYPE_SASL_COMPLETE 12

static const value_string auth_types[] = {
    { PGSQL_AUTH_TYPE_SUCCESS              , "Success" },
    { PGSQL_AUTH_TYPE_KERBEROS4            , "Kerberos V4" },
    { PGSQL_AUTH_TYPE_KERBEROS5            , "Kerberos V5" },
    { PGSQL_AUTH_TYPE_PLAINTEXT            , "Plaintext password" },
    { PGSQL_AUTH_TYPE_CRYPT                , "crypt()ed password" },
    { PGSQL_AUTH_TYPE_MD5                  , "MD5 password" },
    { PGSQL_AUTH_TYPE_SCM                  , "SCM credentials" },
    { PGSQL_AUTH_TYPE_GSSAPI               , "GSSAPI" },
    { PGSQL_AUTH_TYPE_GSSAPI_SSPI_CONTINUE , "GSSAPI/SSPI continue" },
    { PGSQL_AUTH_TYPE_SSPI                 , "SSPI" },
    { PGSQL_AUTH_TYPE_SASL                 , "SASL" },
    { PGSQL_AUTH_TYPE_SASL_CONTINUE        , "SASL continue" },
    { PGSQL_AUTH_TYPE_SASL_COMPLETE        , "SASL complete" },
    { 0, NULL }
};

static const value_string status_vals[] = {
    { 'I', "Idle" },
    { 'T', "In a transaction" },
    { 'E', "In a failed transaction" },
    { 0, NULL }
};

static const value_string format_vals[] = {
    { 0, "Text" },
    { 1, "Binary" },
    { 0, NULL }
};

static void dissect_pgsql_fe_msg(guchar type, guint length, tvbuff_t *tvb,
                                 gint n, proto_tree *tree, packet_info *pinfo,
                                 pgsql_conn_data_t *conv_data)
{
    guchar c;
    gint i, siz;
    char *s;
    proto_tree *shrub;
    gint32 data_length;

    switch (type) {
    /* Password, SASL or GSSAPI Response, depending on context */
    case 'p':
        switch(conv_data->auth_state) {

            case PGSQL_AUTH_SASL_REQUESTED:
                /* SASLInitResponse */
                siz = tvb_strsize(tvb, n);
                proto_tree_add_item(tree, hf_sasl_auth_mech, tvb, n, siz, ENC_ASCII|ENC_NA);
                n += siz;
                proto_tree_add_item_ret_int(tree, hf_sasl_auth_data_length, tvb, n, 4, ENC_BIG_ENDIAN, &data_length);
                n += 4;
                if (data_length) {
                    proto_tree_add_item(tree, hf_sasl_auth_data, tvb, n, data_length, ENC_NA);
                }
                break;

            case PGSQL_AUTH_SASL_CONTINUE:
                proto_tree_add_item(tree, hf_sasl_auth_data, tvb, n, length-4, ENC_NA);
                break;

            case PGSQL_AUTH_GSSAPI_SSPI_DATA:
                proto_tree_add_item(tree, hf_gssapi_sspi_data, tvb, n, length-4, ENC_NA);
                break;

            default:
                siz = tvb_strsize(tvb, n);
                proto_tree_add_item(tree, hf_passwd, tvb, n, siz, ENC_ASCII|ENC_NA);
                break;
        }
        break;

    /* Simple query */
    case 'Q':
        siz = tvb_strsize(tvb, n);
        proto_tree_add_item(tree, hf_query, tvb, n, siz, ENC_ASCII|ENC_NA);
        break;

    /* Parse */
    case 'P':
        siz = tvb_strsize(tvb, n);
        proto_tree_add_item(tree, hf_statement, tvb, n, siz, ENC_ASCII|ENC_NA);
        n += siz;

        siz = tvb_strsize(tvb, n);
        proto_tree_add_item(tree, hf_query, tvb, n, siz, ENC_ASCII|ENC_NA);
        n += siz;

        i = tvb_get_ntohs(tvb, n);
        shrub = proto_tree_add_subtree_format(tree, tvb, n, 2, ett_values, NULL, "Parameters: %d", i);
        n += 2;
        while (i-- > 0) {
            proto_tree_add_item(shrub, hf_typeoid, tvb, n, 4, ENC_BIG_ENDIAN);
            n += 4;
        }
        break;

    /* Bind */
    case 'B':
        siz = tvb_strsize(tvb, n);
        proto_tree_add_item(tree, hf_portal, tvb, n, siz, ENC_ASCII|ENC_NA);
        n += siz;

        siz = tvb_strsize(tvb, n);
        proto_tree_add_item(tree, hf_statement, tvb, n, siz, ENC_ASCII|ENC_NA);
        n += siz;

        i = tvb_get_ntohs(tvb, n);
        shrub = proto_tree_add_subtree_format(tree, tvb, n, 2, ett_values, NULL, "Parameter formats: %d", i);
        n += 2;
        while (i-- > 0) {
            proto_tree_add_item(shrub, hf_format, tvb, n, 2, ENC_BIG_ENDIAN);
            n += 2;
        }

        i = tvb_get_ntohs(tvb, n);
        shrub = proto_tree_add_subtree_format(tree, tvb, n, 2, ett_values, NULL, "Parameter values: %d", i);
        n += 2;
        while (i-- > 0) {
            siz = tvb_get_ntohl(tvb, n);
            proto_tree_add_int(shrub, hf_val_length, tvb, n, 4, siz);
            n += 4;
            if (siz > 0) {
                proto_tree_add_item(shrub, hf_val_data, tvb, n, siz, ENC_NA);
                n += siz;
            }
        }

        i = tvb_get_ntohs(tvb, n);
        shrub = proto_tree_add_subtree_format(tree, tvb, n, 2, ett_values, NULL, "Result formats: %d", i);
        n += 2;
        while (i-- > 0) {
            proto_tree_add_item(shrub, hf_format, tvb, n, 2, ENC_BIG_ENDIAN);
            n += 2;
        }
        break;

    /* Execute */
    case 'E':
        siz = tvb_strsize(tvb, n);
        proto_tree_add_item(tree, hf_portal, tvb, n, siz, ENC_ASCII|ENC_NA);
        n += siz;

        i = tvb_get_ntohl(tvb, n);
        if (i == 0)
            proto_tree_add_uint_format_value(tree, hf_return, tvb, n, 4, i, "all rows");
        else
            proto_tree_add_uint_format_value(tree, hf_return, tvb, n, 4, i, "%d rows", i);
        break;

    /* Describe, Close */
    case 'D':
    case 'C':
        c = tvb_get_guint8(tvb, n);
        if (c == 'P')
            i = hf_portal;
        else
            i = hf_statement;

        n += 1;
        s = tvb_get_stringz_enc(pinfo->pool, tvb, n, &siz, ENC_ASCII);
        proto_tree_add_string(tree, i, tvb, n, siz, s);
        break;

    /* Messages without a type identifier */
    case '\0':
        i = tvb_get_ntohl(tvb, n);
        n += 4;
        length -= n;
        switch (i) {
        /* Startup message */
        case 196608:
            proto_tree_add_item(tree, hf_version_major, tvb, n-4, 2, ENC_BIG_ENDIAN);
            proto_tree_add_item(tree, hf_version_minor, tvb, n-2, 2, ENC_BIG_ENDIAN);
            while ((signed)length > 0) {
                siz = tvb_strsize(tvb, n);
                length -= siz;
                if ((signed)length <= 0) {
                    break;
                }
                proto_tree_add_item(tree, hf_parameter_name,  tvb, n,       siz, ENC_ASCII|ENC_NA);
                i = tvb_strsize(tvb, n+siz);
                proto_tree_add_item(tree, hf_parameter_value, tvb, n + siz, i,   ENC_ASCII|ENC_NA);
                length -= i;

                n += siz+i;
                if (length == 1 && tvb_get_guint8(tvb, n) == 0)
                    break;
            }
            break;

        /* SSL request */
        case 80877103:
            /* Next reply will be a single byte. */
            conv_data->ssl_requested = TRUE;
            break;

        /* Cancellation request */
        case 80877102:
            proto_tree_add_item(tree, hf_pid, tvb, n,   4, ENC_BIG_ENDIAN);
            proto_tree_add_item(tree, hf_key, tvb, n+4, 4, ENC_BIG_ENDIAN);
            break;
        }
        break;

    /* Copy data */
    case 'd':
        proto_tree_add_item(tree, hf_copydata, tvb, n, length-n+1, ENC_NA);
        break;

    /* Copy failure */
    case 'f':
        siz = tvb_strsize(tvb, n);
        proto_tree_add_item(tree, hf_error, tvb, n, siz, ENC_ASCII|ENC_NA);
        break;

    /* Function call */
    case 'F':
        proto_tree_add_item(tree, hf_oid, tvb, n, 4, ENC_BIG_ENDIAN);
        n += 4;

        i = tvb_get_ntohs(tvb, n);
        shrub = proto_tree_add_subtree_format(tree, tvb, n, 2, ett_values, NULL, "Parameter formats: %d", i);
        n += 2;
        while (i-- > 0) {
            proto_tree_add_item(shrub, hf_format, tvb, n, 2, ENC_BIG_ENDIAN);
            n += 2;
        }

        i = tvb_get_ntohs(tvb, n);
        shrub = proto_tree_add_subtree_format(tree, tvb, n, 2, ett_values, NULL, "Parameter values: %d", i);
        n += 2;
        while (i-- > 0) {
            siz = tvb_get_ntohl(tvb, n);
            proto_tree_add_item(shrub, hf_val_length, tvb, n, 4, ENC_BIG_ENDIAN);
            n += 4;
            if (siz > 0) {
                proto_tree_add_item(shrub, hf_val_data, tvb, n, siz, ENC_NA);
                n += siz;
            }
        }

        proto_tree_add_item(tree, hf_format, tvb, n, 2, ENC_BIG_ENDIAN);
        break;
    }
}


static void dissect_pgsql_be_msg(guchar type, guint length, tvbuff_t *tvb,
                                 gint n, proto_tree *tree, packet_info *pinfo,
                                 pgsql_conn_data_t *conv_data)
{
    guchar c;
    gint i, siz;
    char *s, *t;
    gint32 num_nonsupported_options;
    proto_item *ti;
    proto_tree *shrub;
    guint32 auth_type;

    switch (type) {
    /* Authentication request */
    case 'R':
        proto_tree_add_item_ret_uint(tree, hf_authtype, tvb, n, 4, ENC_BIG_ENDIAN, &auth_type);
        switch (auth_type) {
        case PGSQL_AUTH_TYPE_CRYPT:
        case PGSQL_AUTH_TYPE_MD5:
            n += 4;
            siz = (auth_type == PGSQL_AUTH_TYPE_CRYPT ? 2 : 4);
            proto_tree_add_item(tree, hf_salt, tvb, n, siz, ENC_NA);
            break;
        case PGSQL_AUTH_TYPE_GSSAPI_SSPI_CONTINUE:
            conv_data->auth_state = PGSQL_AUTH_GSSAPI_SSPI_DATA;
            proto_tree_add_item(tree, hf_gssapi_sspi_data, tvb, n, length-8, ENC_NA);
            break;
        case PGSQL_AUTH_TYPE_SASL:
            conv_data->auth_state = PGSQL_AUTH_SASL_REQUESTED;
            n += 4;
            while ((guint)n < length) {
                siz = tvb_strsize(tvb, n);
                proto_tree_add_item(tree, hf_sasl_auth_mech, tvb, n, siz, ENC_ASCII|ENC_NA);
                n += siz;
            }
            break;
        case PGSQL_AUTH_TYPE_SASL_CONTINUE:
        case PGSQL_AUTH_TYPE_SASL_COMPLETE:
            conv_data->auth_state = PGSQL_AUTH_SASL_CONTINUE;
            n += 4;
            if ((guint)n < length) {
                proto_tree_add_item(tree, hf_sasl_auth_data, tvb, n, length-8, ENC_NA);
            }
            break;
        }
        break;

    /* Key data */
    case 'K':
        proto_tree_add_item(tree, hf_pid, tvb, n,   4, ENC_BIG_ENDIAN);
        proto_tree_add_item(tree, hf_key, tvb, n+4, 4, ENC_BIG_ENDIAN);
        break;

    /* Parameter status */
    case 'S':
        s = tvb_get_stringz_enc(pinfo->pool, tvb, n, &siz, ENC_ASCII);
        proto_tree_add_string(tree, hf_parameter_name, tvb, n, siz, s);
        n += siz;
        t = tvb_get_stringz_enc(pinfo->pool, tvb, n, &i, ENC_ASCII);
        proto_tree_add_string(tree, hf_parameter_value, tvb, n, i, t);
        break;

    /* Parameter description */
    case 't':
        i = tvb_get_ntohs(tvb, n);
        shrub = proto_tree_add_subtree_format(tree, tvb, n, 2, ett_values, NULL, "Parameters: %d", i);
        n += 2;
        while (i-- > 0) {
            proto_tree_add_item(shrub, hf_typeoid, tvb, n, 4, ENC_BIG_ENDIAN);
            n += 4;
        }
        break;

    /* Row description */
    case 'T':
        i = tvb_get_ntohs(tvb, n);
        ti = proto_tree_add_item(tree, hf_field_count, tvb, n, 2, ENC_BIG_ENDIAN);
        shrub = proto_item_add_subtree(ti, ett_values);
        n += 2;
        while (i-- > 0) {
            proto_tree *twig;
            siz = tvb_strsize(tvb, n);
            ti = proto_tree_add_item(shrub, hf_val_name, tvb, n, siz, ENC_ASCII|ENC_NA);
            twig = proto_item_add_subtree(ti, ett_values);
            n += siz;
            proto_tree_add_item(twig, hf_tableoid, tvb, n, 4, ENC_BIG_ENDIAN);
            n += 4;
            proto_tree_add_item(twig, hf_val_idx, tvb, n, 2, ENC_BIG_ENDIAN);
            n += 2;
            proto_tree_add_item(twig, hf_typeoid, tvb, n, 4, ENC_BIG_ENDIAN);
            n += 4;
            proto_tree_add_item(twig, hf_val_length, tvb, n, 2, ENC_BIG_ENDIAN);
            n += 2;
            proto_tree_add_item(twig, hf_val_mod, tvb, n, 4, ENC_BIG_ENDIAN);
            n += 4;
            proto_tree_add_item(twig, hf_format, tvb, n, 2, ENC_BIG_ENDIAN);
            n += 2;
        }
        break;

    /* Data row */
    case 'D':
        i = tvb_get_ntohs(tvb, n);
        ti = proto_tree_add_item(tree, hf_field_count, tvb, n, 2, ENC_BIG_ENDIAN);
        shrub = proto_item_add_subtree(ti, ett_values);
        n += 2;
        while (i-- > 0) {
            siz = tvb_get_ntohl(tvb, n);
            proto_tree_add_int(shrub, hf_val_length, tvb, n, 4, siz);
            n += 4;
            if (siz > 0) {
                proto_tree_add_item(shrub, hf_val_data, tvb, n, siz, ENC_NA);
                n += siz;
            }
        }
        break;

    /* Command completion */
    case 'C':
        siz = tvb_strsize(tvb, n);
        proto_tree_add_item(tree, hf_tag, tvb, n, siz, ENC_ASCII|ENC_NA);
        break;

    /* Ready */
    case 'Z':
        proto_tree_add_item(tree, hf_status, tvb, n, 1, ENC_BIG_ENDIAN);
        break;

    /* Error, Notice */
    case 'E':
    case 'N':
        length -= 4;
        while ((signed)length > 0) {
            c = tvb_get_guint8(tvb, n);
            if (c == '\0')
                break;
            s = tvb_get_stringz_enc(pinfo->pool, tvb, n+1, &siz, ENC_ASCII);
            i = hf_text;
            switch (c) {
            case 'S': i = hf_severity;          break;
            case 'C': i = hf_code;              break;
            case 'M': i = hf_message;           break;
            case 'D': i = hf_detail;            break;
            case 'H': i = hf_hint;              break;
            case 'P': i = hf_position;          break;
            case 'p': i = hf_internal_position; break;
            case 'q': i = hf_internal_query;    break;
            case 'W': i = hf_where;             break;
            case 's': i = hf_schema_name;       break;
            case 't': i = hf_table_name;        break;
            case 'c': i = hf_column_name;       break;
            case 'd': i = hf_type_name;         break;
            case 'n': i = hf_constraint_name;   break;
            case 'F': i = hf_file;              break;
            case 'L': i = hf_line;              break;
            case 'R': i = hf_routine;           break;
            }
            proto_tree_add_string(tree, i, tvb, n, siz+1, s);
            length -= siz+1;
            n += siz+1;
        }
        break;

    /* NOTICE response */
    case 'A':
        proto_tree_add_item(tree, hf_pid, tvb, n, 4, ENC_BIG_ENDIAN);
        n += 4;
        siz = tvb_strsize(tvb, n);
        proto_tree_add_item(tree, hf_condition, tvb, n, siz, ENC_ASCII|ENC_NA);
        n += siz;
        siz = tvb_strsize(tvb, n);
        if (siz > 1)
            proto_tree_add_item(tree, hf_text, tvb, n, siz, ENC_ASCII|ENC_NA);
        break;

    /* Copy in/out */
    case 'G':
    case 'H':
        proto_tree_add_item(tree, hf_format, tvb, n, 1, ENC_BIG_ENDIAN);
        n += 1;
        i = tvb_get_ntohs(tvb, n);
        shrub = proto_tree_add_subtree_format(tree, tvb, n, 2, ett_values, NULL, "Columns: %d", i);
        n += 2;
        while (i-- > 2) {
            proto_tree_add_item(shrub, hf_format, tvb, n, 2, ENC_BIG_ENDIAN);
            n += 2;
        }
        break;

    /* Copy data */
    case 'd':
        proto_tree_add_item(tree, hf_copydata, tvb, n, length-n+1, ENC_NA);
        break;

    /* Function call response */
    case 'V':
        siz = tvb_get_ntohl(tvb, n);
        proto_tree_add_int(tree, hf_val_length, tvb, n, 4, siz);
        if (siz > 0)
            proto_tree_add_item(tree, hf_val_data, tvb, n+4, siz, ENC_NA);
        break;

    /* Negotiate Protocol Version */
    case 'v':
        proto_tree_add_item(tree, hf_supported_minor_version, tvb, n, 4, ENC_BIG_ENDIAN);
        n += 4;
        proto_tree_add_item_ret_int(tree, hf_number_nonsupported_options, tvb, n, 4, ENC_BIG_ENDIAN, &num_nonsupported_options);
        n += 4;
        while (num_nonsupported_options > 0) {
            siz = tvb_strsize(tvb, n);
            proto_tree_add_item(tree, hf_nonsupported_option, tvb, n, siz, ENC_ASCII|ENC_NA);
            n += siz;
            num_nonsupported_options--;
        }
        break;
    }
}

/* This function is called by tcp_dissect_pdus() to find the size of the
   message starting at tvb[offset]. */
static guint
pgsql_length(packet_info *pinfo _U_, tvbuff_t *tvb, int offset, void *data _U_)
{
    gint n = 0;
    guchar type;
    guint length;

    /* The length is either the four bytes after the type, or, if the
       type is 0, the first four bytes. */
    type = tvb_get_guint8(tvb, offset);
    if (type != '\0')
        n = 1;
    length = tvb_get_ntohl(tvb, offset+n);
    return length+n;
}


/* This function is responsible for dissecting a single message. */

static int
dissect_pgsql_msg(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, void* data _U_)
{
    proto_item *ti, *hidden_item;
    proto_tree *ptree;
    conversation_t      *conversation;
    pgsql_conn_data_t   *conn_data;

    gint n;
    guchar type;
    const char *typestr;
    guint length;
    gboolean fe = (pinfo->match_uint == pinfo->destport);

    conversation = find_or_create_conversation(pinfo);
    conn_data = (pgsql_conn_data_t *)conversation_get_proto_data(conversation, proto_pgsql);
    if (!conn_data) {
        conn_data = wmem_new(wmem_file_scope(), pgsql_conn_data_t);
        conn_data->ssl_requested = FALSE;
        conn_data->auth_state = PGSQL_AUTH_STATE_NONE;
        conversation_add_proto_data(conversation, proto_pgsql, conn_data);
    }

    n = 0;
    type = tvb_get_guint8(tvb, 0);
    if (type != '\0')
        n += 1;
    length = tvb_get_ntohl(tvb, n);

    /* This is like specifying VALS(messages) for hf_type, which we can't do
       directly because of messages without type bytes, and because the type
       interpretation depends on fe. */
    if (fe) {
        /* There are a few frontend messages that have no leading type byte.
           We identify them by the fact that the first byte of their length
           must be zero, and that the next four bytes are a unique tag. */
        if (type == '\0') {
            guint tag = tvb_get_ntohl(tvb, 4);

            if (length == 16 && tag == 80877102)
                typestr = "Cancel request";
            else if (length == 8 && tag == 80877103)
                typestr = "SSL request";
            else if (length == 8 && tag == 80877104)
                typestr = "GSS encrypt request";
            else if (tag == 196608)
                typestr = "Startup message";
            else
                typestr = "Unknown";
        } else if (type == 'p') {
            switch (conn_data->auth_state) {
                case PGSQL_AUTH_SASL_REQUESTED:
                    typestr = "SASLInitialResponse message";
                    break;
                case PGSQL_AUTH_SASL_CONTINUE:
                    typestr = "SASLResponse message";
                    break;
                case PGSQL_AUTH_GSSAPI_SSPI_DATA:
                    typestr = "GSSResponse message";
                    break;
                default:
                    typestr = "Password message";
                    break;
            }
        } else
            typestr = val_to_str_const(type, fe_messages, "Unknown");
    }
    else {
        typestr = val_to_str_const(type, be_messages, "Unknown");
    }

    /* This is a terrible hack. It makes the "Info" column reflect
        the contents of every message in a TCP packet. Could it be
        done any better? */
    col_append_fstr(pinfo->cinfo, COL_INFO, "%s%c",
                    ( first_message ? "" : "/" ), type);
    first_message = FALSE;

    {
        ti = proto_tree_add_item(tree, proto_pgsql, tvb, 0, -1, ENC_NA);
        ptree = proto_item_add_subtree(ti, ett_pgsql);

        n = 1;
        if (type == '\0')
            n = 0;
        proto_tree_add_string(ptree, hf_type, tvb, 0, n, typestr);
        proto_tree_add_item(ptree, hf_length, tvb, n, 4, ENC_BIG_ENDIAN);
        hidden_item = proto_tree_add_boolean(ptree, hf_frontend, tvb, 0, 0, fe);
        proto_item_set_hidden(hidden_item);
        n += 4;

        if (fe)
            dissect_pgsql_fe_msg(type, length, tvb, n, ptree, pinfo, conn_data);
        else
            dissect_pgsql_be_msg(type, length, tvb, n, ptree, pinfo, conn_data);
    }

    return tvb_captured_length(tvb);
}

/* This function is called once per TCP packet. It sets COL_PROTOCOL and
 * identifies FE/BE messages by adding a ">" or "<" to COL_INFO. Then it
 * arranges for each message to be dissected individually. */

static int
dissect_pgsql(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, void* data)
{
    conversation_t      *conversation;
    pgsql_conn_data_t   *conn_data;

    first_message = TRUE;

    conversation = find_or_create_conversation(pinfo);
    conn_data = (pgsql_conn_data_t *)conversation_get_proto_data(conversation, proto_pgsql);

    col_set_str(pinfo->cinfo, COL_PROTOCOL, "PGSQL");
    col_set_str(pinfo->cinfo, COL_INFO,
                    (pinfo->match_uint == pinfo->destport) ?
                     ">" : "<");

    if (conn_data && conn_data->ssl_requested) {
        /* Response to SSLRequest. */
        switch (tvb_get_guint8(tvb, 0)) {
        case 'S':   /* Willing to perform SSL */
            /* Next packet will start using SSL. */
            ssl_starttls_ack(tls_handle, pinfo, pgsql_handle);
            break;
        case 'N':   /* Unwilling to perform SSL */
        default:    /* ErrorMessage when server does not support SSL. */
            /* TODO: maybe add expert info here? */
            break;
        }
        conn_data->ssl_requested = FALSE;
        return tvb_captured_length(tvb);
    }

    tcp_dissect_pdus(tvb, pinfo, tree, pgsql_desegment, 5,
                     pgsql_length, dissect_pgsql_msg, data);
    return tvb_captured_length(tvb);
}

void
proto_register_pgsql(void)
{
    static hf_register_info hf[] = {
        { &hf_frontend,
          { "Frontend", "pgsql.frontend", FT_BOOLEAN, BASE_NONE, NULL, 0x0,
            "True for messages from the frontend, false otherwise.",
            HFILL }
        },
        { &hf_type,
          { "Type", "pgsql.type", FT_STRING, BASE_NONE, NULL, 0,
            "A one-byte message type identifier.", HFILL }
        },
        { &hf_length,
          { "Length", "pgsql.length", FT_UINT32, BASE_DEC, NULL, 0,
            "The length of the message (not including the type).",
            HFILL }
        },
        { &hf_version_major,
          { "Protocol major version", "pgsql.version_major", FT_UINT16, BASE_DEC, NULL, 0,
            NULL, HFILL }
        },
        { &hf_version_minor,
          { "Protocol minor version", "pgsql.version_minor", FT_UINT16, BASE_DEC, NULL, 0,
            NULL, HFILL }
        },
        { &hf_supported_minor_version,
          { "Supported minor version", "pgsql.version_supported_minor", FT_UINT32, BASE_DEC, NULL, 0,
            "Newest minor protocol version supported by the server for the major protocol version requested by the client.", HFILL }
        },
        { &hf_number_nonsupported_options,
          { "Number nonsupported options", "pgsql.number_nonsupported_options", FT_INT32, BASE_DEC, NULL, 0,
            NULL, HFILL }
        },
        { &hf_nonsupported_option,
          { "Nonsupported option", "pgsql.nonsupported_option", FT_STRINGZ, BASE_NONE, NULL, 0,
            NULL, HFILL }
        },
        { &hf_parameter_name,
          { "Parameter name", "pgsql.parameter_name", FT_STRINGZ,
            BASE_NONE, NULL, 0, "The name of a database parameter.",
            HFILL }
        },
        { &hf_parameter_value,
          { "Parameter value", "pgsql.parameter_value", FT_STRINGZ,
            BASE_NONE, NULL, 0, "The value of a database parameter.",
            HFILL }
        },
        { &hf_query,
          { "Query", "pgsql.query", FT_STRINGZ, BASE_NONE, NULL, 0,
            "A query string.", HFILL }
        },
        { &hf_passwd,
          { "Password", "pgsql.password", FT_STRINGZ, BASE_NONE, NULL, 0,
            "A password.", HFILL }
        },
        { &hf_authtype,
          { "Authentication type", "pgsql.authtype", FT_UINT32, BASE_DEC,
            VALS(auth_types), 0,
            "The type of authentication requested by the backend.", HFILL }
        },
        { &hf_salt,
          { "Salt value", "pgsql.salt", FT_BYTES, BASE_NONE, NULL, 0,
            "The salt to use while encrypting a password.", HFILL }
        },
        { &hf_gssapi_sspi_data,
          { "GSSAPI or SSPI data", "pgsql.auth.gssapi_sspi.data", FT_BYTES, BASE_NONE, NULL, 0,
            NULL, HFILL }
        },
        { &hf_sasl_auth_mech,
          { "SASL authentication mechanism", "pgsql.auth.sasl.mech", FT_STRINGZ, BASE_NONE, NULL, 0,
            NULL, HFILL }
        },
        { &hf_sasl_auth_data_length,
          { "SASL authentication data length", "pgsql.auth.sasl.data.length", FT_INT32, BASE_DEC, NULL, 0,
            NULL, HFILL }
        },
        { &hf_sasl_auth_data,
          { "SASL authentication data", "pgsql.auth.sasl.data", FT_BYTES, BASE_NONE, NULL, 0,
            NULL, HFILL }
        },
        { &hf_statement,
          { "Statement", "pgsql.statement", FT_STRINGZ, BASE_NONE, NULL, 0,
            "The name of a prepared statement.", HFILL }
        },
        { &hf_portal,
          { "Portal", "pgsql.portal", FT_STRINGZ, BASE_NONE, NULL, 0,
            "The name of a portal.", HFILL }
        },
        { &hf_return,
          { "Returns", "pgsql.returns", FT_UINT32, BASE_DEC,
            NULL, 0,
            NULL, HFILL }
        },
        { &hf_tag,
          { "Tag", "pgsql.tag", FT_STRINGZ, BASE_NONE, NULL, 0,
            "A completion tag.", HFILL }
        },
        { &hf_status,
          { "Status", "pgsql.status", FT_UINT8, BASE_DEC, VALS(status_vals),
            0, "The transaction status of the backend.", HFILL }
        },
        { &hf_copydata,
          { "Copy data", "pgsql.copydata", FT_BYTES, BASE_NONE, NULL, 0,
            "Data sent following a Copy-in or Copy-out response.", HFILL }
        },
        { &hf_error,
          { "Error", "pgsql.error", FT_STRINGZ, BASE_NONE, NULL, 0,
            "An error message.", HFILL }
        },
        { &hf_pid,
          { "PID", "pgsql.pid", FT_UINT32, BASE_DEC, NULL, 0,
            "The process ID of a backend.", HFILL }
        },
        { &hf_key,
          { "Key", "pgsql.key", FT_UINT32, BASE_DEC, NULL, 0,
            "The secret key used by a particular backend.", HFILL }
        },
        { &hf_condition,
          { "Condition", "pgsql.condition", FT_STRINGZ, BASE_NONE, NULL, 0,
            "The name of a NOTIFY condition.", HFILL }
        },
        { &hf_text,
          { "Text", "pgsql.text", FT_STRINGZ, BASE_NONE, NULL, 0,
            "Text from the backend.", HFILL }
        },
        { &hf_tableoid,
          { "Table OID", "pgsql.oid.table", FT_UINT32, BASE_DEC, NULL, 0,
            "The object identifier of a table.", HFILL }
        },
        { &hf_typeoid,
          { "Type OID", "pgsql.oid.type", FT_UINT32, BASE_DEC, NULL, 0,
            "The object identifier of a type.", HFILL }
        },
        { &hf_oid,
          { "OID", "pgsql.oid", FT_UINT32, BASE_DEC, NULL, 0,
            "An object identifier.", HFILL }
        },
        { &hf_format,
          { "Format", "pgsql.format", FT_UINT16, BASE_DEC, VALS(format_vals),
            0, "A format specifier.", HFILL }
        },
        { &hf_field_count,
          { "Field count", "pgsql.field.count", FT_UINT16, BASE_DEC, NULL, 0,
            "The number of fields within a row.", HFILL }
        },
        { &hf_val_name,
          { "Column name", "pgsql.col.name", FT_STRINGZ, BASE_NONE, NULL, 0,
            "The name of a column.", HFILL }
        },
        { &hf_val_idx,
          { "Column index", "pgsql.col.index", FT_UINT32, BASE_DEC, NULL, 0,
            "The position of a column within a row.", HFILL }
        },
        { &hf_val_length,
          { "Column length", "pgsql.val.length", FT_INT32, BASE_DEC, NULL, 0,
            "The length of a parameter value, in bytes. -1 means NULL.",
            HFILL }
        },
        { &hf_val_data,
          { "Data", "pgsql.val.data", FT_BYTES, BASE_NONE, NULL, 0,
            "Parameter data.", HFILL }
        },
        { &hf_val_mod,
          { "Type modifier", "pgsql.col.typemod", FT_INT32, BASE_DEC, NULL, 0,
            "The type modifier for a column.", HFILL }
        },
        { &hf_severity,
          { "Severity", "pgsql.severity", FT_STRINGZ, BASE_NONE, NULL, 0,
            "Message severity.", HFILL }
        },
        { &hf_code,
          { "Code", "pgsql.code", FT_STRINGZ, BASE_NONE, NULL, 0,
            "SQLState code.", HFILL }
        },
        { &hf_message,
          { "Message", "pgsql.message", FT_STRINGZ, BASE_NONE, NULL, 0,
            "Error message.", HFILL }
        },
        { &hf_detail,
          { "Detail", "pgsql.detail", FT_STRINGZ, BASE_NONE, NULL, 0,
            "Detailed error message.", HFILL }
        },
        { &hf_hint,
          { "Hint", "pgsql.hint", FT_STRINGZ, BASE_NONE, NULL, 0,
            "A suggestion to resolve an error.", HFILL }
        },
        { &hf_position,
          { "Position", "pgsql.position", FT_STRINGZ, BASE_NONE, NULL, 0,
            "The index of the error within the query string.", HFILL }
        },
        { &hf_internal_position,
          { "Position (Internal)", "pgsql.internal_position", FT_STRINGZ, BASE_NONE, NULL, 0,
            "The index of the error within the internally-generated query string.", HFILL }
        },
        { &hf_internal_query,
          { "Query (Internal)", "pgsql.internal_query", FT_STRINGZ, BASE_NONE, NULL, 0,
            "The internally-generated query string", HFILL }
        },
        { &hf_where,
          { "Context", "pgsql.where", FT_STRINGZ, BASE_NONE, NULL, 0,
            "The context in which an error occurred.", HFILL }
        },
        { &hf_schema_name,
          { "Schema", "pgsql.schema_name", FT_STRINGZ, BASE_NONE, NULL, 0,
            "The schema with which an error is associated.", HFILL }
        },
        { &hf_table_name,
          { "Table", "pgsql.table_name", FT_STRINGZ, BASE_NONE, NULL, 0,
            "The table with which an error is associated.", HFILL }
        },
        { &hf_column_name,
          { "Column", "pgsql.column_name", FT_STRINGZ, BASE_NONE, NULL, 0,
            "The column with which an error is associated.", HFILL }
        },
        { &hf_type_name,
          { "Type", "pgsql.type_name", FT_STRINGZ, BASE_NONE, NULL, 0,
            "The date type with which an error is associated.", HFILL }
        },
        { &hf_constraint_name,
          { "Constraint", "pgsql.constraint_name", FT_STRINGZ, BASE_NONE, NULL, 0,
            "The constraint with which an error is associated.", HFILL }
        },
        { &hf_file,
          { "File", "pgsql.file", FT_STRINGZ, BASE_NONE, NULL, 0,
            "The source-code file where an error was reported.", HFILL }
        },
        { &hf_line,
          { "Line", "pgsql.line", FT_STRINGZ, BASE_NONE, NULL, 0,
            "The line number on which an error was reported.", HFILL }
        },
        { &hf_routine,
          { "Routine", "pgsql.routine", FT_STRINGZ, BASE_NONE, NULL, 0,
            "The routine that reported an error.", HFILL }
        }
    };

    static gint *ett[] = {
        &ett_pgsql,
        &ett_values
    };

    proto_pgsql = proto_register_protocol("PostgreSQL", "PGSQL", "pgsql");
    proto_register_field_array(proto_pgsql, hf, array_length(hf));
    proto_register_subtree_array(ett, array_length(ett));
}

void
proto_reg_handoff_pgsql(void)
{
    pgsql_handle = create_dissector_handle(dissect_pgsql, proto_pgsql);

    dissector_add_uint_with_preference("tcp.port", PGSQL_PORT, pgsql_handle);

    tls_handle = find_dissector_add_dependency("tls", proto_pgsql);
}

/*
 * 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:
 */
