libpq-int.h

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/*-------------------------------------------------------------------------
 *
 * libpq-int.h
 *    This file contains internal definitions meant to be used only by
 *    the frontend libpq library, not by applications that call it.
 *
 *    An application can include this file if it wants to bypass the
 *    official API defined by libpq-fe.h, but code that does so is much
 *    more likely to break across PostgreSQL releases than code that uses
 *    only the official API.
 *
 * Portions Copyright (c) 1996-2023, PostgreSQL Global Development Group
 * Portions Copyright (c) 1994, Regents of the University of California
 *
 * src/interfaces/libpq/libpq-int.h
 *
 *-------------------------------------------------------------------------
 */
 
#ifndef LIBPQ_INT_H
#define LIBPQ_INT_H
 
/* We assume libpq-fe.h has already been included. */
#include "libpq-events.h"
 
#include <netdb.h>
#include <sys/socket.h>
#include <time.h>
/* MinGW has sys/time.h, but MSVC doesn't */
#ifndef _MSC_VER
#include <sys/time.h>
#endif
 
#ifdef WIN32
#include "pthread-win32.h"
#else
#include <pthread.h>
#endif
#include <signal.h>
 
/* include stuff common to fe and be */
#include "libpq/pqcomm.h"
/* include stuff found in fe only */
#include "fe-auth-sasl.h"
#include "pqexpbuffer.h"
 
#ifdef ENABLE_GSS
#if defined(HAVE_GSSAPI_H)
#include <gssapi.h>
#else
#include <gssapi/gssapi.h>
#endif
#endif
 
#ifdef ENABLE_SSPI
#define SECURITY_WIN32
#if defined(WIN32) && !defined(_MSC_VER)
#include <ntsecapi.h>
#endif
#include <security.h>
#undef SECURITY_WIN32
 
#ifndef ENABLE_GSS
/*
 * Define a fake structure compatible with GSSAPI on Unix.
 */
typedef struct
{
    void       *value;
    int         length;
} gss_buffer_desc;
#endif
#endif                          /* ENABLE_SSPI */
 
#ifdef USE_OPENSSL
#include <openssl/ssl.h>
#include <openssl/err.h>
 
#ifndef OPENSSL_NO_ENGINE
#define USE_SSL_ENGINE
#endif
#endif                          /* USE_OPENSSL */
 
#include "common/pg_prng.h"
 
/*
 * POSTGRES backend dependent Constants.
 */
#define CMDSTATUS_LEN 64        /* should match COMPLETION_TAG_BUFSIZE */
 
/*
 * PGresult and the subsidiary types PGresAttDesc, PGresAttValue
 * represent the result of a query (or more precisely, of a single SQL
 * command --- a query string given to PQexec can contain multiple commands).
 * Note we assume that a single command can return at most one tuple group,
 * hence there is no need for multiple descriptor sets.
 */
 
/* Subsidiary-storage management structure for PGresult.
 * See space management routines in fe-exec.c for details.
 * Note that space[k] refers to the k'th byte starting from the physical
 * head of the block --- it's a union, not a struct!
 */
typedef union pgresult_data PGresult_data;
 
union pgresult_data
{
    PGresult_data *next;        /* link to next block, or NULL */
    char        space[1];       /* dummy for accessing block as bytes */
};
 
/* Data about a single parameter of a prepared statement */
typedef struct pgresParamDesc
{
    Oid         typid;          /* type id */
} PGresParamDesc;
 
/*
 * Data for a single attribute of a single tuple
 *
 * We use char* for Attribute values.
 *
 * The value pointer always points to a null-terminated area; we add a
 * null (zero) byte after whatever the backend sends us.  This is only
 * particularly useful for text values ... with a binary value, the
 * value might have embedded nulls, so the application can't use C string
 * operators on it.  But we add a null anyway for consistency.
 * Note that the value itself does not contain a length word.
 *
 * A NULL attribute is a special case in two ways: its len field is NULL_LEN
 * and its value field points to null_field in the owning PGresult.  All the
 * NULL attributes in a query result point to the same place (there's no need
 * to store a null string separately for each one).
 */
 
#define NULL_LEN        (-1)    /* pg_result len for NULL value */
 
typedef struct pgresAttValue
{
    int         len;            /* length in bytes of the value */
    char       *value;          /* actual value, plus terminating zero byte */
} PGresAttValue;
 
/* Typedef for message-field list entries */
typedef struct pgMessageField
{
    struct pgMessageField *next;    /* list link */
    char        code;           /* field code */
    char        contents[FLEXIBLE_ARRAY_MEMBER];    /* value, nul-terminated */
} PGMessageField;
 
/* Fields needed for notice handling */
typedef struct
{
    PQnoticeReceiver noticeRec; /* notice message receiver */
    void       *noticeRecArg;
    PQnoticeProcessor noticeProc;   /* notice message processor */
    void       *noticeProcArg;
} PGNoticeHooks;
 
typedef struct PGEvent
{
    PGEventProc proc;           /* the function to call on events */
    char       *name;           /* used only for error messages */
    void       *passThrough;    /* pointer supplied at registration time */
    void       *data;           /* optional state (instance) data */
    bool        resultInitialized;  /* T if RESULTCREATE/COPY succeeded */
} PGEvent;
 
struct pg_result
{
    int         ntups;
    int         numAttributes;
    PGresAttDesc *attDescs;
    PGresAttValue **tuples;     /* each PGresult tuple is an array of
                                 * PGresAttValue's */
    int         tupArrSize;     /* allocated size of tuples array */
    int         numParameters;
    PGresParamDesc *paramDescs;
    ExecStatusType resultStatus;
    char        cmdStatus[CMDSTATUS_LEN];   /* cmd status from the query */
    int         binary;         /* binary tuple values if binary == 1,
                                 * otherwise text */
 
    /*
     * These fields are copied from the originating PGconn, so that operations
     * on the PGresult don't have to reference the PGconn.
     */
    PGNoticeHooks noticeHooks;
    PGEvent    *events;
    int         nEvents;
    int         client_encoding;    /* encoding id */
 
    /*
     * Error information (all NULL if not an error result).  errMsg is the
     * "overall" error message returned by PQresultErrorMessage.  If we have
     * per-field info then it is stored in a linked list.
     */
    char       *errMsg;         /* error message, or NULL if no error */
    PGMessageField *errFields;  /* message broken into fields */
    char       *errQuery;       /* text of triggering query, if available */
 
    /* All NULL attributes in the query result point to this null string */
    char        null_field[1];
 
    /*
     * Space management information.  Note that attDescs and error stuff, if
     * not null, point into allocated blocks.  But tuples points to a
     * separately malloc'd block, so that we can realloc it.
     */
    PGresult_data *curBlock;    /* most recently allocated block */
    int         curOffset;      /* start offset of free space in block */
    int         spaceLeft;      /* number of free bytes remaining in block */
 
    size_t      memorySize;     /* total space allocated for this PGresult */
};
 
/* PGAsyncStatusType defines the state of the query-execution state machine */
typedef enum
{
    PGASYNC_IDLE,               /* nothing's happening, dude */
    PGASYNC_BUSY,               /* query in progress */
    PGASYNC_READY,              /* query done, waiting for client to fetch
                                 * result */
    PGASYNC_READY_MORE,         /* query done, waiting for client to fetch
                                 * result, more results expected from this
                                 * query */
    PGASYNC_COPY_IN,            /* Copy In data transfer in progress */
    PGASYNC_COPY_OUT,           /* Copy Out data transfer in progress */
    PGASYNC_COPY_BOTH,          /* Copy In/Out data transfer in progress */
    PGASYNC_PIPELINE_IDLE,      /* "Idle" between commands in pipeline mode */
} PGAsyncStatusType;
 
/* Target server type (decoded value of target_session_attrs) */
typedef enum
{
    SERVER_TYPE_ANY = 0,        /* Any server (default) */
    SERVER_TYPE_READ_WRITE,     /* Read-write server */
    SERVER_TYPE_READ_ONLY,      /* Read-only server */
    SERVER_TYPE_PRIMARY,        /* Primary server */
    SERVER_TYPE_STANDBY,        /* Standby server */
    SERVER_TYPE_PREFER_STANDBY, /* Prefer standby server */
    SERVER_TYPE_PREFER_STANDBY_PASS2    /* second pass - behaves same as ANY */
} PGTargetServerType;
 
/* Target server type (decoded value of load_balance_hosts) */
typedef enum
{
    LOAD_BALANCE_DISABLE = 0,   /* Use the existing host order (default) */
    LOAD_BALANCE_RANDOM,        /* Randomly shuffle the hosts */
} PGLoadBalanceType;
 
/* Boolean value plus a not-known state, for GUCs we might have to fetch */
typedef enum
{
    PG_BOOL_UNKNOWN = 0,        /* Currently unknown */
    PG_BOOL_YES,                /* Yes (true) */
    PG_BOOL_NO                  /* No (false) */
} PGTernaryBool;
 
/* Typedef for the EnvironmentOptions[] array */
typedef struct PQEnvironmentOption
{
    const char *envName,        /* name of an environment variable */
               *pgName;         /* name of corresponding SET variable */
} PQEnvironmentOption;
 
/* Typedef for parameter-status list entries */
typedef struct pgParameterStatus
{
    struct pgParameterStatus *next; /* list link */
    char       *name;           /* parameter name */
    char       *value;          /* parameter value */
    /* Note: name and value are stored in same malloc block as struct is */
} pgParameterStatus;
 
/* large-object-access data ... allocated only if large-object code is used. */
typedef struct pgLobjfuncs
{
    Oid         fn_lo_open;     /* OID of backend function lo_open      */
    Oid         fn_lo_close;    /* OID of backend function lo_close     */
    Oid         fn_lo_creat;    /* OID of backend function lo_creat     */
    Oid         fn_lo_create;   /* OID of backend function lo_create    */
    Oid         fn_lo_unlink;   /* OID of backend function lo_unlink    */
    Oid         fn_lo_lseek;    /* OID of backend function lo_lseek     */
    Oid         fn_lo_lseek64;  /* OID of backend function lo_lseek64   */
    Oid         fn_lo_tell;     /* OID of backend function lo_tell      */
    Oid         fn_lo_tell64;   /* OID of backend function lo_tell64    */
    Oid         fn_lo_truncate; /* OID of backend function lo_truncate  */
    Oid         fn_lo_truncate64;   /* OID of function lo_truncate64 */
    Oid         fn_lo_read;     /* OID of backend function LOread       */
    Oid         fn_lo_write;    /* OID of backend function LOwrite      */
} PGlobjfuncs;
 
/* PGdataValue represents a data field value being passed to a row processor.
 * It could be either text or binary data; text data is not zero-terminated.
 * A SQL NULL is represented by len < 0; then value is still valid but there
 * are no data bytes there.
 */
typedef struct pgDataValue
{
    int         len;            /* data length in bytes, or <0 if NULL */
    const char *value;          /* data value, without zero-termination */
} PGdataValue;
 
/* Host address type enum for struct pg_conn_host */
typedef enum pg_conn_host_type
{
    CHT_HOST_NAME,
    CHT_HOST_ADDRESS,
    CHT_UNIX_SOCKET
} pg_conn_host_type;
 
/*
 * PGQueryClass tracks which query protocol is in use for each command queue
 * entry, or special operation in execution
 */
typedef enum
{
    PGQUERY_SIMPLE,             /* simple Query protocol (PQexec) */
    PGQUERY_EXTENDED,           /* full Extended protocol (PQexecParams) */
    PGQUERY_PREPARE,            /* Parse only (PQprepare) */
    PGQUERY_DESCRIBE,           /* Describe Statement or Portal */
    PGQUERY_SYNC,               /* Sync (at end of a pipeline) */
    PGQUERY_CLOSE               /* Close Statement or Portal */
} PGQueryClass;
 
/*
 * An entry in the pending command queue.
 */
typedef struct PGcmdQueueEntry
{
    PGQueryClass queryclass;    /* Query type */
    char       *query;          /* SQL command, or NULL if none/unknown/OOM */
    struct PGcmdQueueEntry *next;   /* list link */
} PGcmdQueueEntry;
 
/*
 * pg_conn_host stores all information about each of possibly several hosts
 * mentioned in the connection string.  Most fields are derived by splitting
 * the relevant connection parameter (e.g., pghost) at commas.
 */
typedef struct pg_conn_host
{
    pg_conn_host_type type;     /* type of host address */
    char       *host;           /* host name or socket path */
    char       *hostaddr;       /* host numeric IP address */
    char       *port;           /* port number (always provided) */
    char       *password;       /* password for this host, read from the
                                 * password file; NULL if not sought or not
                                 * found in password file. */
} pg_conn_host;
 
/*
 * PGconn stores all the state data associated with a single connection
 * to a backend.
 */
struct pg_conn
{
    /* Saved values of connection options */
    char       *pghost;         /* the machine on which the server is running,
                                 * or a path to a UNIX-domain socket, or a
                                 * comma-separated list of machines and/or
                                 * paths; if NULL, use DEFAULT_PGSOCKET_DIR */
    char       *pghostaddr;     /* the numeric IP address of the machine on
                                 * which the server is running, or a
                                 * comma-separated list of same.  Takes
                                 * precedence over pghost. */
    char       *pgport;         /* the server's communication port number, or
                                 * a comma-separated list of ports */
    char       *connect_timeout;    /* connection timeout (numeric string) */
    char       *pgtcp_user_timeout; /* tcp user timeout (numeric string) */
    char       *client_encoding_initial;    /* encoding to use */
    char       *pgoptions;      /* options to start the backend with */
    char       *appname;        /* application name */
    char       *fbappname;      /* fallback application name */
    char       *dbName;         /* database name */
    char       *replication;    /* connect as the replication standby? */
    char       *pguser;         /* Postgres username and password, if any */
    char       *pgpass;
    char       *pgpassfile;     /* path to a file containing password(s) */
    char       *channel_binding;    /* channel binding mode
                                     * (require,prefer,disable) */
    char       *keepalives;     /* use TCP keepalives? */
    char       *keepalives_idle;    /* time between TCP keepalives */
    char       *keepalives_interval;    /* time between TCP keepalive
                                         * retransmits */
    char       *keepalives_count;   /* maximum number of TCP keepalive
                                     * retransmits */
    char       *sslmode;        /* SSL mode (require,prefer,allow,disable) */
    char       *sslcompression; /* SSL compression (0 or 1) */
    char       *sslkey;         /* client key filename */
    char       *sslcert;        /* client certificate filename */
    char       *sslpassword;    /* client key file password */
    char       *sslcertmode;    /* client cert mode (require,allow,disable) */
    char       *sslrootcert;    /* root certificate filename */
    char       *sslcrl;         /* certificate revocation list filename */
    char       *sslcrldir;      /* certificate revocation list directory name */
    char       *sslsni;         /* use SSL SNI extension (0 or 1) */
    char       *requirepeer;    /* required peer credentials for local sockets */
    char       *gssencmode;     /* GSS mode (require,prefer,disable) */
    char       *krbsrvname;     /* Kerberos service name */
    char       *gsslib;         /* What GSS library to use ("gssapi" or
                                 * "sspi") */
    char       *gssdelegation;  /* Try to delegate GSS credentials? (0 or 1) */
    char       *ssl_min_protocol_version;   /* minimum TLS protocol version */
    char       *ssl_max_protocol_version;   /* maximum TLS protocol version */
    char       *target_session_attrs;   /* desired session properties */
    char       *require_auth;   /* name of the expected auth method */
    char       *load_balance_hosts; /* load balance over hosts */
 
    /* Optional file to write trace info to */
    FILE       *Pfdebug;
    int         traceFlags;
 
    /* Callback procedures for notice message processing */
    PGNoticeHooks noticeHooks;
 
    /* Event procs registered via PQregisterEventProc */
    PGEvent    *events;         /* expandable array of event data */
    int         nEvents;        /* number of active events */
    int         eventArraySize; /* allocated array size */
 
    /* Status indicators */
    ConnStatusType status;
    PGAsyncStatusType asyncStatus;
    PGTransactionStatusType xactStatus; /* never changes to ACTIVE */
    char        last_sqlstate[6];   /* last reported SQLSTATE */
    bool        options_valid;  /* true if OK to attempt connection */
    bool        nonblocking;    /* whether this connection is using nonblock
                                 * sending semantics */
    PGpipelineStatus pipelineStatus;    /* status of pipeline mode */
    bool        singleRowMode;  /* return current query result row-by-row? */
    char        copy_is_binary; /* 1 = copy binary, 0 = copy text */
    int         copy_already_done;  /* # bytes already returned in COPY OUT */
    PGnotify   *notifyHead;     /* oldest unreported Notify msg */
    PGnotify   *notifyTail;     /* newest unreported Notify msg */
 
    /* Support for multiple hosts in connection string */
    int         nconnhost;      /* # of hosts named in conn string */
    int         whichhost;      /* host we're currently trying/connected to */
    pg_conn_host *connhost;     /* details about each named host */
    char       *connip;         /* IP address for current network connection */
 
    /*
     * The pending command queue as a singly-linked list.  Head is the command
     * currently in execution, tail is where new commands are added.
     */
    PGcmdQueueEntry *cmd_queue_head;
    PGcmdQueueEntry *cmd_queue_tail;
 
    /*
     * To save malloc traffic, we don't free entries right away; instead we
     * save them in this list for possible reuse.
     */
    PGcmdQueueEntry *cmd_queue_recycle;
 
    /* Connection data */
    pgsocket    sock;           /* FD for socket, PGINVALID_SOCKET if
                                 * unconnected */
    SockAddr    laddr;          /* Local address */
    SockAddr    raddr;          /* Remote address */
    ProtocolVersion pversion;   /* FE/BE protocol version in use */
    int         sversion;       /* server version, e.g. 70401 for 7.4.1 */
    bool        auth_req_received;  /* true if any type of auth req received */
    bool        password_needed;    /* true if server demanded a password */
    bool        gssapi_used;    /* true if authenticated via gssapi */
    bool        sigpipe_so;     /* have we masked SIGPIPE via SO_NOSIGPIPE? */
    bool        sigpipe_flag;   /* can we mask SIGPIPE via MSG_NOSIGNAL? */
    bool        write_failed;   /* have we had a write failure on sock? */
    char       *write_err_msg;  /* write error message, or NULL if OOM */
 
    bool        auth_required;  /* require an authentication challenge from
                                 * the server? */
    uint32      allowed_auth_methods;   /* bitmask of acceptable AuthRequest
                                         * codes */
    bool        client_finished_auth;   /* have we finished our half of the
                                         * authentication exchange? */
 
 
    /* Transient state needed while establishing connection */
    PGTargetServerType target_server_type;  /* desired session properties */
    PGLoadBalanceType load_balance_type;    /* desired load balancing
                                             * algorithm */
    bool        try_next_addr;  /* time to advance to next address/host? */
    bool        try_next_host;  /* time to advance to next connhost[]? */
    int         naddr;          /* number of addresses returned by getaddrinfo */
    int         whichaddr;      /* the address currently being tried */
    AddrInfo   *addr;           /* the array of addresses for the currently
                                 * tried host */
    bool        send_appname;   /* okay to send application_name? */
 
    /* Miscellaneous stuff */
    int         be_pid;         /* PID of backend --- needed for cancels */
    int         be_key;         /* key of backend --- needed for cancels */
    pgParameterStatus *pstatus; /* ParameterStatus data */
    int         client_encoding;    /* encoding id */
    bool        std_strings;    /* standard_conforming_strings */
    PGTernaryBool default_transaction_read_only;    /* default_transaction_read_only */
    PGTernaryBool in_hot_standby;   /* in_hot_standby */
    PGVerbosity verbosity;      /* error/notice message verbosity */
    PGContextVisibility show_context;   /* whether to show CONTEXT field */
    PGlobjfuncs *lobjfuncs;     /* private state for large-object access fns */
    pg_prng_state prng_state;   /* prng state for load balancing connections */
 
 
    /* Buffer for data received from backend and not yet processed */
    char       *inBuffer;       /* currently allocated buffer */
    int         inBufSize;      /* allocated size of buffer */
    int         inStart;        /* offset to first unconsumed data in buffer */
    int         inCursor;       /* next byte to tentatively consume */
    int         inEnd;          /* offset to first position after avail data */
 
    /* Buffer for data not yet sent to backend */
    char       *outBuffer;      /* currently allocated buffer */
    int         outBufSize;     /* allocated size of buffer */
    int         outCount;       /* number of chars waiting in buffer */
 
    /* State for constructing messages in outBuffer */
    int         outMsgStart;    /* offset to msg start (length word); if -1,
                                 * msg has no length word */
    int         outMsgEnd;      /* offset to msg end (so far) */
 
    /* Row processor interface workspace */
    PGdataValue *rowBuf;        /* array for passing values to rowProcessor */
    int         rowBufLen;      /* number of entries allocated in rowBuf */
 
    /*
     * Status for asynchronous result construction.  If result isn't NULL, it
     * is a result being constructed or ready to return.  If result is NULL
     * and error_result is true, then we need to return a PGRES_FATAL_ERROR
     * result, but haven't yet constructed it; text for the error has been
     * appended to conn->errorMessage.  (Delaying construction simplifies
     * dealing with out-of-memory cases.)  If next_result isn't NULL, it is a
     * PGresult that will replace "result" after we return that one.
     */
    PGresult   *result;         /* result being constructed */
    bool        error_result;   /* do we need to make an ERROR result? */
    PGresult   *next_result;    /* next result (used in single-row mode) */
 
    /* Assorted state for SASL, SSL, GSS, etc */
    const pg_fe_sasl_mech *sasl;
    void       *sasl_state;
    int         scram_sha_256_iterations;
 
    /* SSL structures */
    bool        ssl_in_use;
    bool        ssl_cert_requested; /* Did the server ask us for a cert? */
    bool        ssl_cert_sent;  /* Did we send one in reply? */
 
#ifdef USE_SSL
    bool        allow_ssl_try;  /* Allowed to try SSL negotiation */
    bool        wait_ssl_try;   /* Delay SSL negotiation until after
                                 * attempting normal connection */
#ifdef USE_OPENSSL
    SSL        *ssl;            /* SSL status, if have SSL connection */
    X509       *peer;           /* X509 cert of server */
#ifdef USE_SSL_ENGINE
    ENGINE     *engine;         /* SSL engine, if any */
#else
    void       *engine;         /* dummy field to keep struct the same if
                                 * OpenSSL version changes */
#endif
    bool        crypto_loaded;  /* Track if libcrypto locking callbacks have
                                 * been done for this connection. This can be
                                 * removed once support for OpenSSL 1.0.2 is
                                 * removed as this locking is handled
                                 * internally in OpenSSL >= 1.1.0. */
#endif                          /* USE_OPENSSL */
#endif                          /* USE_SSL */
 
#ifdef ENABLE_GSS
    gss_ctx_id_t gctx;          /* GSS context */
    gss_name_t  gtarg_nam;      /* GSS target name */
 
    /* The following are encryption-only */
    bool        try_gss;        /* GSS attempting permitted */
    bool        gssenc;         /* GSS encryption is usable */
    gss_cred_id_t gcred;        /* GSS credential temp storage. */
 
    /* GSS encryption I/O state --- see fe-secure-gssapi.c */
    char       *gss_SendBuffer; /* Encrypted data waiting to be sent */
    int         gss_SendLength; /* End of data available in gss_SendBuffer */
    int         gss_SendNext;   /* Next index to send a byte from
                                 * gss_SendBuffer */
    int         gss_SendConsumed;   /* Number of *unencrypted* bytes consumed
                                     * for current contents of gss_SendBuffer */
    char       *gss_RecvBuffer; /* Received, encrypted data */
    int         gss_RecvLength; /* End of data available in gss_RecvBuffer */
    char       *gss_ResultBuffer;   /* Decryption of data in gss_RecvBuffer */
    int         gss_ResultLength;   /* End of data available in
                                     * gss_ResultBuffer */
    int         gss_ResultNext; /* Next index to read a byte from
                                 * gss_ResultBuffer */
    uint32      gss_MaxPktSize; /* Maximum size we can encrypt and fit the
                                 * results into our output buffer */
#endif
 
#ifdef ENABLE_SSPI
    CredHandle *sspicred;       /* SSPI credentials handle */
    CtxtHandle *sspictx;        /* SSPI context */
    char       *sspitarget;     /* SSPI target name */
    int         usesspi;        /* Indicate if SSPI is in use on the
                                 * connection */
#endif
 
    /*
     * Buffer for current error message.  This is cleared at the start of any
     * connection attempt or query cycle; after that, all code should append
     * messages to it, never overwrite.
     *
     * In some situations we might report an error more than once in a query
     * cycle.  If so, errorMessage accumulates text from all the errors, and
     * errorReported tracks how much we've already reported, so that the
     * individual error PGresult objects don't contain duplicative text.
     */
    PQExpBufferData errorMessage;   /* expansible string */
    int         errorReported;  /* # bytes of string already reported */
 
    /* Buffer for receiving various parts of messages */
    PQExpBufferData workBuffer; /* expansible string */
};
 
/* PGcancel stores all data necessary to cancel a connection. A copy of this
 * data is required to safely cancel a connection running on a different
 * thread.
 */
struct pg_cancel
{
    SockAddr    raddr;          /* Remote address */
    int         be_pid;         /* PID of backend --- needed for cancels */
    int         be_key;         /* key of backend --- needed for cancels */
    int         pgtcp_user_timeout; /* tcp user timeout */
    int         keepalives;     /* use TCP keepalives? */
    int         keepalives_idle;    /* time between TCP keepalives */
    int         keepalives_interval;    /* time between TCP keepalive
                                         * retransmits */
    int         keepalives_count;   /* maximum number of TCP keepalive
                                     * retransmits */
};
 
 
/* String descriptions of the ExecStatusTypes.
 * direct use of this array is deprecated; call PQresStatus() instead.
 */
extern char *const pgresStatus[];
 
 
#ifdef USE_SSL
 
#ifndef WIN32
#define USER_CERT_FILE      ".postgresql/postgresql.crt"
#define USER_KEY_FILE       ".postgresql/postgresql.key"
#define ROOT_CERT_FILE      ".postgresql/root.crt"
#define ROOT_CRL_FILE       ".postgresql/root.crl"
#else
/* On Windows, the "home" directory is already PostgreSQL-specific */
#define USER_CERT_FILE      "postgresql.crt"
#define USER_KEY_FILE       "postgresql.key"
#define ROOT_CERT_FILE      "root.crt"
#define ROOT_CRL_FILE       "root.crl"
#endif
 
#endif                          /* USE_SSL */
 
/* ----------------
 * Internal functions of libpq
 * Functions declared here need to be visible across files of libpq,
 * but are not intended to be called by applications.  We use the
 * convention "pqXXX" for internal functions, vs. the "PQxxx" names
 * used for application-visible routines.
 * ----------------
 */
 
/* === in fe-connect.c === */
 
extern void pqDropConnection(PGconn *conn, bool flushInput);
extern int  pqPacketSend(PGconn *conn, char pack_type,
                         const void *buf, size_t buf_len);
extern bool pqGetHomeDirectory(char *buf, int bufsize);
 
extern pgthreadlock_t pg_g_threadlock;
 
#define pglock_thread()     pg_g_threadlock(true)
#define pgunlock_thread()   pg_g_threadlock(false)
 
/* === in fe-exec.c === */
 
extern void pqSetResultError(PGresult *res, PQExpBuffer errorMessage, int offset);
extern void *pqResultAlloc(PGresult *res, size_t nBytes, bool isBinary);
extern char *pqResultStrdup(PGresult *res, const char *str);
extern void pqClearAsyncResult(PGconn *conn);
extern void pqSaveErrorResult(PGconn *conn);
extern PGresult *pqPrepareAsyncResult(PGconn *conn);
extern void pqInternalNotice(const PGNoticeHooks *hooks, const char *fmt,...) pg_attribute_printf(2, 3);
extern void pqSaveMessageField(PGresult *res, char code,
                               const char *value);
extern void pqSaveParameterStatus(PGconn *conn, const char *name,
                                  const char *value);
extern int  pqRowProcessor(PGconn *conn, const char **errmsgp);
extern void pqCommandQueueAdvance(PGconn *conn);
extern int  PQsendQueryContinue(PGconn *conn, const char *query);
 
/* === in fe-protocol3.c === */
 
extern char *pqBuildStartupPacket3(PGconn *conn, int *packetlen,
                                   const PQEnvironmentOption *options);
extern void pqParseInput3(PGconn *conn);
extern int  pqGetErrorNotice3(PGconn *conn, bool isError);
extern void pqBuildErrorMessage3(PQExpBuffer msg, const PGresult *res,
                                 PGVerbosity verbosity, PGContextVisibility show_context);
extern int  pqGetNegotiateProtocolVersion3(PGconn *conn);
extern int  pqGetCopyData3(PGconn *conn, char **buffer, int async);
extern int  pqGetline3(PGconn *conn, char *s, int maxlen);
extern int  pqGetlineAsync3(PGconn *conn, char *buffer, int bufsize);
extern int  pqEndcopy3(PGconn *conn);
extern PGresult *pqFunctionCall3(PGconn *conn, Oid fnid,
                                 int *result_buf, int *actual_result_len,
                                 int result_is_int,
                                 const PQArgBlock *args, int nargs);
 
/* === in fe-misc.c === */
 
 /*
  * "Get" and "Put" routines return 0 if successful, EOF if not. Note that for
  * Get, EOF merely means the buffer is exhausted, not that there is
  * necessarily any error.
  */
extern int  pqCheckOutBufferSpace(size_t bytes_needed, PGconn *conn);
extern int  pqCheckInBufferSpace(size_t bytes_needed, PGconn *conn);
extern int  pqGetc(char *result, PGconn *conn);
extern int  pqPutc(char c, PGconn *conn);
extern int  pqGets(PQExpBuffer buf, PGconn *conn);
extern int  pqGets_append(PQExpBuffer buf, PGconn *conn);
extern int  pqPuts(const char *s, PGconn *conn);
extern int  pqGetnchar(char *s, size_t len, PGconn *conn);
extern int  pqSkipnchar(size_t len, PGconn *conn);
extern int  pqPutnchar(const char *s, size_t len, PGconn *conn);
extern int  pqGetInt(int *result, size_t bytes, PGconn *conn);
extern int  pqPutInt(int value, size_t bytes, PGconn *conn);
extern int  pqPutMsgStart(char msg_type, PGconn *conn);
extern int  pqPutMsgEnd(PGconn *conn);
extern int  pqReadData(PGconn *conn);
extern int  pqFlush(PGconn *conn);
extern int  pqWait(int forRead, int forWrite, PGconn *conn);
extern int  pqWaitTimed(int forRead, int forWrite, PGconn *conn,
                        time_t finish_time);
extern int  pqReadReady(PGconn *conn);
extern int  pqWriteReady(PGconn *conn);
 
/* === in fe-secure.c === */
 
extern int  pqsecure_initialize(PGconn *, bool, bool);
extern PostgresPollingStatusType pqsecure_open_client(PGconn *);
extern void pqsecure_close(PGconn *);
extern ssize_t pqsecure_read(PGconn *, void *ptr, size_t len);
extern ssize_t pqsecure_write(PGconn *, const void *ptr, size_t len);
extern ssize_t pqsecure_raw_read(PGconn *, void *ptr, size_t len);
extern ssize_t pqsecure_raw_write(PGconn *, const void *ptr, size_t len);
 
#if !defined(WIN32)
extern int  pq_block_sigpipe(sigset_t *osigset, bool *sigpipe_pending);
extern void pq_reset_sigpipe(sigset_t *osigset, bool sigpipe_pending,
                             bool got_epipe);
#endif
 
/* === SSL === */
 
/*
 * The SSL implementation provides these functions.
 */
 
/*
 *  Implementation of PQinitSSL().
 */
extern void pgtls_init_library(bool do_ssl, int do_crypto);
 
/*
 * Initialize SSL library.
 *
 * The conn parameter is only used to be able to pass back an error
 * message - no connection-local setup is made here.  do_ssl controls
 * if SSL is initialized, and do_crypto does the same for the crypto
 * part.
 *
 * Returns 0 if OK, -1 on failure (adding a message to conn->errorMessage).
 */
extern int  pgtls_init(PGconn *conn, bool do_ssl, bool do_crypto);
 
/*
 *  Begin or continue negotiating a secure session.
 */
extern PostgresPollingStatusType pgtls_open_client(PGconn *conn);
 
/*
 *  Close SSL connection.
 */
extern void pgtls_close(PGconn *conn);
 
/*
 *  Read data from a secure connection.
 *
 * On failure, this function is responsible for appending a suitable message
 * to conn->errorMessage.  The caller must still inspect errno, but only
 * to determine whether to continue/retry after error.
 */
extern ssize_t pgtls_read(PGconn *conn, void *ptr, size_t len);
 
/*
 *  Is there unread data waiting in the SSL read buffer?
 */
extern bool pgtls_read_pending(PGconn *conn);
 
/*
 *  Write data to a secure connection.
 *
 * On failure, this function is responsible for appending a suitable message
 * to conn->errorMessage.  The caller must still inspect errno, but only
 * to determine whether to continue/retry after error.
 */
extern ssize_t pgtls_write(PGconn *conn, const void *ptr, size_t len);
 
/*
 * Get the hash of the server certificate, for SCRAM channel binding type
 * tls-server-end-point.
 *
 * NULL is sent back to the caller in the event of an error, with an
 * error message for the caller to consume.
 */
extern char *pgtls_get_peer_certificate_hash(PGconn *conn, size_t *len);
 
/*
 * Verify that the server certificate matches the host name we connected to.
 *
 * The certificate's Common Name and Subject Alternative Names are considered.
 *
 * Returns 1 if the name matches, and 0 if it does not. On error, returns
 * -1, and sets the libpq error message.
 *
 */
extern int  pgtls_verify_peer_name_matches_certificate_guts(PGconn *conn,
                                                            int *names_examined,
                                                            char **first_name);
 
/* === GSSAPI === */
 
#ifdef ENABLE_GSS
 
/*
 * Establish a GSSAPI-encrypted connection.
 */
extern PostgresPollingStatusType pqsecure_open_gss(PGconn *conn);
 
/*
 * Read and write functions for GSSAPI-encrypted connections, with internal
 * buffering to handle nonblocking sockets.
 */
extern ssize_t pg_GSS_write(PGconn *conn, const void *ptr, size_t len);
extern ssize_t pg_GSS_read(PGconn *conn, void *ptr, size_t len);
#endif
 
/* === in fe-trace.c === */
 
extern void pqTraceOutputMessage(PGconn *conn, const char *message,
                                 bool toServer);
extern void pqTraceOutputNoTypeByteMessage(PGconn *conn, const char *message);
 
/* === miscellaneous macros === */
 
/*
 * Reset the conn's error-reporting state.
 */
#define pqClearConnErrorState(conn) \
    (resetPQExpBuffer(&(conn)->errorMessage), \
     (conn)->errorReported = 0)
 
/*
 * Check whether we have a PGresult pending to be returned --- either a
 * constructed one in conn->result, or a "virtual" error result that we
 * don't intend to materialize until the end of the query cycle.
 */
#define pgHavePendingResult(conn) \
    ((conn)->result != NULL || (conn)->error_result)
 
/*
 * this is so that we can check if a connection is non-blocking internally
 * without the overhead of a function call
 */
#define pqIsnonblocking(conn)   ((conn)->nonblocking)
 
/*
 * Connection's outbuffer threshold, for pipeline mode.
 */
#define OUTBUFFER_THRESHOLD 65536
 
#ifdef ENABLE_NLS
extern char *libpq_gettext(const char *msgid) pg_attribute_format_arg(1);
extern char *libpq_ngettext(const char *msgid, const char *msgid_plural, unsigned long n) pg_attribute_format_arg(1) pg_attribute_format_arg(2);
#else
#define libpq_gettext(x) (x)
#define libpq_ngettext(s, p, n) ((n) == 1 ? (s) : (p))
#endif
/*
 * libpq code should use the above, not _(), since that would use the
 * surrounding programs's message catalog.
 */
#undef _
 
extern void libpq_append_error(PQExpBuffer errorMessage, const char *fmt,...) pg_attribute_printf(2, 3);
extern void libpq_append_conn_error(PGconn *conn, const char *fmt,...) pg_attribute_printf(2, 3);
 
/*
 * These macros are needed to let error-handling code be portable between
 * Unix and Windows.  (ugh)
 */
#ifdef WIN32
#define SOCK_ERRNO (WSAGetLastError())
#define SOCK_STRERROR winsock_strerror
#define SOCK_ERRNO_SET(e) WSASetLastError(e)
#else
#define SOCK_ERRNO errno
#define SOCK_STRERROR strerror_r
#define SOCK_ERRNO_SET(e) (errno = (e))
#endif
 
#endif                          /* LIBPQ_INT_H */