oauth-utils.c

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/*-------------------------------------------------------------------------
 *
 * oauth-utils.c
 *
 *    "Glue" helpers providing a copy of some internal APIs from libpq. At
 *    some point in the future, we might be able to deduplicate.
 *
 * Portions Copyright (c) 1996-2025, PostgreSQL Global Development Group
 * Portions Copyright (c) 1994, Regents of the University of California
 *
 * IDENTIFICATION
 *    src/interfaces/libpq-oauth/oauth-utils.c
 *
 *-------------------------------------------------------------------------
 */
 
#include "postgres_fe.h"
 
#include <signal.h>
 
#include "oauth-utils.h"
 
#ifndef USE_DYNAMIC_OAUTH
#error oauth-utils.c is not supported in static builds
#endif
 
#ifdef LIBPQ_INT_H
#error do not rely on libpq-int.h in dynamic builds of libpq-oauth
#endif
 
/*
 * Function pointers set by libpq_oauth_init().
 */
 
pgthreadlock_t pg_g_threadlock;
static libpq_gettext_func libpq_gettext_impl;
 
conn_errorMessage_func conn_errorMessage;
conn_oauth_client_id_func conn_oauth_client_id;
conn_oauth_client_secret_func conn_oauth_client_secret;
conn_oauth_discovery_uri_func conn_oauth_discovery_uri;
conn_oauth_issuer_id_func conn_oauth_issuer_id;
conn_oauth_scope_func conn_oauth_scope;
conn_sasl_state_func conn_sasl_state;
 
set_conn_altsock_func set_conn_altsock;
set_conn_oauth_token_func set_conn_oauth_token;
 
/*-
 * Initializes libpq-oauth by setting necessary callbacks.
 *
 * The current implementation relies on the following private implementation
 * details of libpq:
 *
 * - pg_g_threadlock: protects libcurl initialization if the underlying Curl
 *   installation is not threadsafe
 *
 * - libpq_gettext: translates error messages using libpq's message domain
 *
 * The implementation also needs access to several members of the PGconn struct,
 * which are not guaranteed to stay in place across minor versions. Accessors
 * (named conn_*) and mutators (named set_conn_*) are injected here.
 */
void
libpq_oauth_init(pgthreadlock_t threadlock_impl,
                 libpq_gettext_func gettext_impl,
                 conn_errorMessage_func errmsg_impl,
                 conn_oauth_client_id_func clientid_impl,
                 conn_oauth_client_secret_func clientsecret_impl,
                 conn_oauth_discovery_uri_func discoveryuri_impl,
                 conn_oauth_issuer_id_func issuerid_impl,
                 conn_oauth_scope_func scope_impl,
                 conn_sasl_state_func saslstate_impl,
                 set_conn_altsock_func setaltsock_impl,
                 set_conn_oauth_token_func settoken_impl)
{
    pg_g_threadlock = threadlock_impl;
    libpq_gettext_impl = gettext_impl;
    conn_errorMessage = errmsg_impl;
    conn_oauth_client_id = clientid_impl;
    conn_oauth_client_secret = clientsecret_impl;
    conn_oauth_discovery_uri = discoveryuri_impl;
    conn_oauth_issuer_id = issuerid_impl;
    conn_oauth_scope = scope_impl;
    conn_sasl_state = saslstate_impl;
    set_conn_altsock = setaltsock_impl;
    set_conn_oauth_token = settoken_impl;
}
 
/*
 * Append a formatted string to the error message buffer of the given
 * connection, after translating it.  This is a copy of libpq's internal API.
 */
void
libpq_append_conn_error(PGconn *conn, const char *fmt,...)
{
    int         save_errno = errno;
    bool        done;
    va_list     args;
    PQExpBuffer errorMessage = conn_errorMessage(conn);
 
    Assert(fmt[strlen(fmt) - 1] != '\n');
 
    if (PQExpBufferBroken(errorMessage))
        return;                 /* already failed */
 
    /* Loop in case we have to retry after enlarging the buffer. */
    do
    {
        errno = save_errno;
        va_start(args, fmt);
        done = appendPQExpBufferVA(errorMessage, libpq_gettext(fmt), args);
        va_end(args);
    } while (!done);
 
    appendPQExpBufferChar(errorMessage, '\n');
}
 
#ifdef ENABLE_NLS
 
/*
 * A shim that defers to the actual libpq_gettext().
 */
char *
libpq_gettext(const char *msgid)
{
    if (!libpq_gettext_impl)
    {
        /*
         * Possible if the libpq build didn't enable NLS but the libpq-oauth
         * build did. That's an odd mismatch, but we can handle it.
         *
         * Note that callers of libpq_gettext() have to treat the return value
         * as if it were const, because builds without NLS simply pass through
         * their argument.
         */
        return unconstify(char *, msgid);
    }
 
    return libpq_gettext_impl(msgid);
}
 
#endif                          /* ENABLE_NLS */
 
/*
 * Returns true if the PGOAUTHDEBUG=UNSAFE flag is set in the environment.
 */
bool
oauth_unsafe_debugging_enabled(void)
{
    const char *env = getenv("PGOAUTHDEBUG");
 
    return (env && strcmp(env, "UNSAFE") == 0);
}
 
/*
 * Duplicate SOCK_ERRNO* definitions from libpq-int.h, for use by
 * pq_block/reset_sigpipe().
 */
#ifdef WIN32
#define SOCK_ERRNO (WSAGetLastError())
#define SOCK_ERRNO_SET(e) WSASetLastError(e)
#else
#define SOCK_ERRNO errno
#define SOCK_ERRNO_SET(e) (errno = (e))
#endif
 
/*
 *  Block SIGPIPE for this thread. This is a copy of libpq's internal API.
 */
int
pq_block_sigpipe(sigset_t *osigset, bool *sigpipe_pending)
{
    sigset_t    sigpipe_sigset;
    sigset_t    sigset;
 
    sigemptyset(&sigpipe_sigset);
    sigaddset(&sigpipe_sigset, SIGPIPE);
 
    /* Block SIGPIPE and save previous mask for later reset */
    SOCK_ERRNO_SET(pthread_sigmask(SIG_BLOCK, &sigpipe_sigset, osigset));
    if (SOCK_ERRNO)
        return -1;
 
    /* We can have a pending SIGPIPE only if it was blocked before */
    if (sigismember(osigset, SIGPIPE))
    {
        /* Is there a pending SIGPIPE? */
        if (sigpending(&sigset) != 0)
            return -1;
 
        if (sigismember(&sigset, SIGPIPE))
            *sigpipe_pending = true;
        else
            *sigpipe_pending = false;
    }
    else
        *sigpipe_pending = false;
 
    return 0;
}
 
/*
 *  Discard any pending SIGPIPE and reset the signal mask. This is a copy of
 *  libpq's internal API.
 */
void
pq_reset_sigpipe(sigset_t *osigset, bool sigpipe_pending, bool got_epipe)
{
    int         save_errno = SOCK_ERRNO;
    int         signo;
    sigset_t    sigset;
 
    /* Clear SIGPIPE only if none was pending */
    if (got_epipe && !sigpipe_pending)
    {
        if (sigpending(&sigset) == 0 &&
            sigismember(&sigset, SIGPIPE))
        {
            sigset_t    sigpipe_sigset;
 
            sigemptyset(&sigpipe_sigset);
            sigaddset(&sigpipe_sigset, SIGPIPE);
 
            sigwait(&sigpipe_sigset, &signo);
        }
    }
 
    /* Restore saved block mask */
    pthread_sigmask(SIG_SETMASK, osigset, NULL);
 
    SOCK_ERRNO_SET(save_errno);
}