/* $Id: asyncns.c 27 2007-02-16 13:51:03Z lennart $ */

/***

  This file is part of libasyncns.

  libasyncns is free software; you can redistribute it and/or modify

  it under the terms of the GNU Lesser General Public License as

  published by the Free Software Foundation; either version 2 of the

  License, or (at your option) any later version.

  libasyncns is distributed in the hope that it will be useful, but

  WITHOUT ANY WARRANTY; without even the implied warranty of

  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU

  General Public License for more details.

  You should have received a copy of the GNU Lesser General Public

  License along with libasyncns; if not, write to the Free Software

  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307

  USA.

***/

/*#undef HAVE_PTHREAD */

#include <glib.h>

#include <assert.h>

#include <fcntl.h>

#include <signal.h>

#include <unistd.h>

#include <sys/select.h>

#include <stdio.h>

#include <string.h>

#include <stdlib.h>

#include <errno.h>

#include <sys/wait.h>

#include <sys/types.h>

#include <pwd.h>

#include <netinet/in.h>

#include <arpa/nameser.h>

#include <resolv.h>

#ifdef HAVE_SYS_PRCTL_H

#include <sys/prctl.h>

#endif

#if HAVE_PTHREAD

#include <pthread.h>

#endif

#include "asyncns.h"

#define MAX_WORKERS 16

#define MAX_QUERIES 256

#define BUFSIZE (10240)

typedef enum {

    REQUEST_ADDRINFO,

    RESPONSE_ADDRINFO,

    REQUEST_NAMEINFO,

    RESPONSE_NAMEINFO,

    REQUEST_RES_QUERY,

    REQUEST_RES_SEARCH,

    RESPONSE_RES,

    REQUEST_TERMINATE

} query_type_t;

enum {

    REQUEST_RECV_FD = 0,

    REQUEST_SEND_FD = 1,

    RESPONSE_RECV_FD = 2,

    RESPONSE_SEND_FD = 3

};

struct asyncns {

    int fds[4];

#ifndef HAVE_PTHREAD    

    pid_t workers[MAX_WORKERS];

#else

    pthread_t workers[MAX_WORKERS];

#endif

    unsigned valid_workers;

    unsigned current_id, current_index;

    asyncns_query_t* queries[MAX_QUERIES];

    asyncns_query_t *done_head, *done_tail;

    int n_queries;

};

struct asyncns_query {

    asyncns_t *asyncns;

    int done;

    unsigned id;

    query_type_t type;

    asyncns_query_t *done_next, *done_prev;

    int ret;

    struct addrinfo *addrinfo;

    char *serv, *host;

    void *userdata;

};

typedef struct rheader {

    query_type_t type;

    unsigned id;

    size_t length;

} rheader_t;

typedef struct addrinfo_request {

    struct rheader header;

    int hints_is_null;

    int ai_flags;

    int ai_family;

    int ai_socktype;

    int ai_protocol;

    size_t node_len, service_len;

} addrinfo_request_t;

typedef struct addrinfo_response {

    struct rheader header;

    int ret;

} addrinfo_response_t;

typedef struct addrinfo_serialization {

    int ai_flags;

    int ai_family;

    int ai_socktype;

    int ai_protocol;

    size_t ai_addrlen;

    size_t canonname_len;

} addrinfo_serialization_t;

typedef struct nameinfo_request {

    struct rheader header;

    int flags;

    socklen_t sockaddr_len;

    int gethost, getserv;

} nameinfo_request_t;

typedef struct nameinfo_response {

    struct rheader header;

    size_t hostlen, servlen;

    int ret;

} nameinfo_response_t;

typedef struct res_query_request {

    struct rheader header;

    int class;

    int type;

    size_t dlen;

} res_request_t;

typedef struct res_query_response {

    struct rheader header;

    int ret;

} res_response_t;

static int fd_nonblock(int fd) {

    int i;

    assert(fd >= 0);

    if ((i = fcntl(fd, F_GETFL, 0)) < 0)

        return -1;

    if (i & O_NONBLOCK)

        return 0;

    return fcntl(fd, F_SETFL, i | O_NONBLOCK);

}

static int fd_cloexec(int fd) {

    int v;

    assert(fd >= 0);

    if ((v = fcntl(fd, F_GETFD, 0)) < 0)

        return -1;

    if (v & FD_CLOEXEC)

        return 0;

    return fcntl(fd, F_SETFD, v | FD_CLOEXEC);

}

static void *serialize_addrinfo(void *p, const struct addrinfo *ai, size_t *length, size_t maxlength) {

    addrinfo_serialization_t *s = p;

    size_t cnl, l;

    assert(p);

    assert(ai);

    assert(length);

    assert(*length <= maxlength);

    cnl = (ai->ai_canonname ? strlen(ai->ai_canonname)+1 : 0);

    l = sizeof(addrinfo_serialization_t) + ai->ai_addrlen + cnl;

    if (*length + l > maxlength)

        return NULL;

    s->ai_flags = ai->ai_flags;

    s->ai_family = ai->ai_family;

    s->ai_socktype = ai->ai_socktype;

    s->ai_protocol = ai->ai_protocol;

    s->ai_addrlen = ai->ai_addrlen;

    s->canonname_len = cnl;

    memcpy((uint8_t*) p + sizeof(addrinfo_serialization_t), ai->ai_addr, ai->ai_addrlen);

    if (ai->ai_canonname)

        strcpy((char*) p + sizeof(addrinfo_serialization_t) + ai->ai_addrlen, ai->ai_canonname);

    *length += l;

    return (uint8_t*) p + l;

}

static int send_addrinfo_reply(int out_fd, unsigned id, int ret, struct addrinfo *ai) {

    uint8_t data[BUFSIZE];

    addrinfo_response_t *resp = (addrinfo_response_t*) data;

    assert(out_fd >= 0);

    resp->header.type = RESPONSE_ADDRINFO;

    resp->header.id = id;

    resp->header.length = sizeof(addrinfo_response_t);

    resp->ret = ret;

    if (ret == 0 && ai) {

        void *p = data + sizeof(addrinfo_response_t);

        while (ai && p) {

            p = serialize_addrinfo(p, ai, &resp->header.length, BUFSIZE);

            ai = ai->ai_next;

        }

    }

    if (ai)

        freeaddrinfo(ai);

    return send(out_fd, resp, resp->header.length, 0);

}

static int send_nameinfo_reply(int out_fd, unsigned id, int ret, const char *host, const char *serv) {

    uint8_t data[BUFSIZE];

    size_t hl, sl;

    nameinfo_response_t *resp = (nameinfo_response_t*) data;

    assert(out_fd >= 0);

    sl = serv ? strlen(serv)+1 : 0;

    hl = host ? strlen(host)+1 : 0;

    resp->header.type = RESPONSE_NAMEINFO;

    resp->header.id = id;

    resp->header.length = sizeof(nameinfo_response_t) + hl + sl;

    resp->ret = ret;

    resp->hostlen = hl;

    resp->servlen = sl;

    assert(sizeof(data) >= resp->header.length);

    if (host)

        memcpy(data + sizeof(nameinfo_response_t), host, hl);

    if (serv)

        memcpy(data + sizeof(nameinfo_response_t) + hl, serv, sl);

    return send(out_fd, resp, resp->header.length, 0);

}

static int send_res_reply(int out_fd, unsigned id, const unsigned char *answer, int ret) {

    uint8_t data[BUFSIZE];

    res_response_t *resp = (res_response_t *) data;

    assert(out_fd >= 0);

    resp->header.type = RESPONSE_RES;

    resp->header.id = id;

    resp->header.length = sizeof(res_response_t) + (ret < 0 ? 0 : ret);

    resp->ret = (ret < 0) ? -errno : ret;

    assert(sizeof(data) >= resp->header.length);

    if (ret > 0)

        memcpy(data + sizeof(res_response_t), answer, ret);

    return send(out_fd, resp, resp->header.length, 0);

}

static int handle_request(int out_fd, const rheader_t *req, size_t length) {

    assert(out_fd >= 0);

    assert(req);

    assert(length >= sizeof(rheader_t));

    assert(length == req->length);

    switch (req->type) {

        case REQUEST_ADDRINFO: {

            struct addrinfo ai, *result = NULL;

            const addrinfo_request_t *ai_req = (const addrinfo_request_t*) req;

            const char *node, *service;

            int ret;

            assert(length >= sizeof(addrinfo_request_t));

            assert(length == sizeof(addrinfo_request_t) + ai_req->node_len + ai_req->service_len);

            memset(&ai, 0, sizeof(ai));

            ai.ai_flags = ai_req->ai_flags;

            ai.ai_family = ai_req->ai_family;

            ai.ai_socktype = ai_req->ai_socktype;

            ai.ai_protocol = ai_req->ai_protocol;

            node = ai_req->node_len ? (const char*) req + sizeof(addrinfo_request_t) : NULL;

            service = ai_req->service_len ? (const char*) req + sizeof(addrinfo_request_t) + ai_req->node_len : NULL;

            /*printf("[getaddrinfo for '%s']\n", node);*/

            ret = getaddrinfo(node, service,

                              ai_req->hints_is_null ? NULL : &ai,

                              &result);

            /*printf("[return value: %d: '%s']\n", ret, gai_strerror(ret));*/

            /* send_addrinfo_reply() frees result */

            return send_addrinfo_reply(out_fd, req->id, ret, result);

        }

        case REQUEST_NAMEINFO: {

            int ret;

            const nameinfo_request_t *ni_req = (const nameinfo_request_t*) req;

            char hostbuf[NI_MAXHOST], servbuf[NI_MAXSERV];

            const struct sockaddr *sa;

            assert(length >= sizeof(nameinfo_request_t));

            assert(length == sizeof(nameinfo_request_t) + ni_req->sockaddr_len);

            sa = (const struct sockaddr*) ((const char*) req + sizeof(nameinfo_request_t));

            ret = getnameinfo(sa, ni_req->sockaddr_len,

                              ni_req->gethost ? hostbuf : NULL, ni_req->gethost ? sizeof(hostbuf) : 0,

                              ni_req->getserv ? servbuf : NULL, ni_req->getserv ? sizeof(servbuf) : 0,

                              ni_req->flags);

            return send_nameinfo_reply(out_fd, req->id, ret,

                                       ret == 0 && ni_req->gethost ? hostbuf : NULL,

                                       ret == 0 && ni_req->getserv ? servbuf : NULL);

        }

        case REQUEST_RES_QUERY: 

        case REQUEST_RES_SEARCH: {

            int ret;

            unsigned char answer[BUFSIZE];

            const res_request_t *res_req = (const res_request_t *)req;

            const char *dname;

            assert(length >= sizeof(res_request_t));

            assert(length == sizeof(res_request_t) + res_req->dlen + 1);

            dname = (const char *) req + sizeof(res_request_t);

            if (req->type == REQUEST_RES_QUERY) { 

                /*printf("[res query for '%s']\n", dname);*/

                ret = res_query(dname, res_req->class, res_req->type, 

                                answer, BUFSIZE);

                /*printf("[return value: %d]\n", ret);*/

            } else {

                ret = res_search(dname, res_req->class, res_req->type, 

                                 answer, BUFSIZE);

            }

            return send_res_reply(out_fd, req->id, answer, ret);

        }

        case REQUEST_TERMINATE: {

            /* Quit */

            return -1;

        }

        default:

            ;

    }

    return 0;

}

#ifndef HAVE_PTHREAD

static int process_worker(int in_fd, int out_fd) {

    int have_death_sig = 0;

    assert(in_fd > 2);

    assert(out_fd > 2);

    int no_warn;

    close(0);

    close(1);

    close(2);

    open("/dev/null", O_RDONLY);

    open("/dev/null", O_WRONLY);

    open("/dev/null", O_WRONLY);

    no_warn = chdir("/");

    if (geteuid() == 0) {

        struct passwd *pw;

        if ((pw = getpwnam("nobody"))) {

#ifdef HAVE_SETRESUID            

            setresuid(pw->pw_uid, pw->pw_uid, pw->pw_uid);

#elif HAVE_SETREUID

            setreuid(pw->pw_uid, pw->pw_uid);

#else

            setuid(pw->pw_uid);