/*
 * testcode/delayer.c - debug program that delays queries to a server.
 *
 * Copyright (c) 2008, NLnet Labs. All rights reserved.
 *
 * This software is open source.
 * 
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 
 * Redistributions of source code must retain the above copyright notice,
 * this list of conditions and the following disclaimer.
 * 
 * Redistributions in binary form must reproduce the above copyright notice,
 * this list of conditions and the following disclaimer in the documentation
 * and/or other materials provided with the distribution.
 * 
 * Neither the name of the NLNET LABS nor the names of its contributors may
 * be used to endorse or promote products derived from this software without
 * specific prior written permission.
 * 
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
 * HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED
 * TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
 * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
 * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
 * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

/**
 * \file
 *
 * This program delays queries made. It performs as a proxy to another
 * server and delays queries to it.
 */

#include "config.h"
#ifdef HAVE_GETOPT_H
#include <getopt.h>
#endif
#ifdef HAVE_TIME_H
#include <time.h>
#endif
#include <sys/time.h>
#include "util/net_help.h"
#include "util/config_file.h"
#include "sldns/sbuffer.h"
#include <signal.h>

/** number of reads per select for delayer */
#define TRIES_PER_SELECT 100

/**
 * The ring buffer
 */
struct ringbuf {
        /** base of buffer */
        uint8_t* buf;
        /** size of buffer */
        size_t size;
        /** low mark, items start here */
        size_t low;
        /** high mark, items end here */
        size_t high;
};

/**
 * List of proxy fds that return replies from the server to our clients.
 */
struct proxy {
        /** the fd to listen for replies from server */
        int s;
        /** last time this was used */
        struct timeval lastuse;
        /** remote address */
        struct sockaddr_storage addr;
        /** length of addr */
        socklen_t addr_len;
        /** number of queries waiting (in total) */
        size_t numwait;
        /** number of queries sent to server (in total) */
        size_t numsent;
        /** numberof answers returned to client (in total) */
        size_t numreturn;
        /** how many times repurposed */
        size_t numreuse;
        /** next in proxylist */
        struct proxy* next;
};

/**
 * An item that has to be TCP relayed
 */
struct tcp_send_list {
        /** the data item */
        uint8_t* item;
        /** size of item */
        size_t len;
        /** time when the item can be transmitted on */
        struct timeval wait;
        /** how much of the item has already been transmitted */
        size_t done;
        /** next in list */
        struct tcp_send_list* next;
};

/**
 * List of TCP proxy fd pairs to TCP connect client to server 
 */
struct tcp_proxy {
        /** the fd to listen for client query */
        int client_s;
        /** the fd to listen for server answer */
        int server_s;

        /** remote client address */
        struct sockaddr_storage addr;
        /** length of address */
        socklen_t addr_len;
        /** timeout on this entry */
        struct timeval timeout;

        /** list of query items to send to server */
        struct tcp_send_list* querylist;
        /** last in query list */
        struct tcp_send_list* querylast;
        /** list of answer items to send to client */
        struct tcp_send_list* answerlist;
        /** last in answerlist */
        struct tcp_send_list* answerlast;

        /** next in list */
        struct tcp_proxy* next;
};

/** usage information for delayer */
static void usage(char* argv[])
{
        printf("usage: %s [options]\n", argv[0]);
        printf("        -f addr : use addr, forward to that server, @port.\n");
        printf("        -b addr : bind to this address to listen.\n");
        printf("        -p port : bind to this port (use 0 for random).\n");
        printf("        -m mem  : use this much memory for waiting queries.\n");
        printf("        -d delay: UDP queries are delayed n milliseconds.\n");
        printf("                  TCP is delayed twice (on send, on recv).\n");
        printf("        -h      : this help message\n");
        exit(1);
}

/** timeval compare, t1 < t2 */
static int
dl_tv_smaller(struct timeval* t1, const struct timeval* t2) 
{
#ifndef S_SPLINT_S
        if(t1->tv_sec < t2->tv_sec)
                return 1;
        if(t1->tv_sec == t2->tv_sec &&
                t1->tv_usec < t2->tv_usec)
                return 1;
#endif
        return 0;
}

/** timeval add, t1 += t2 */
static void
dl_tv_add(struct timeval* t1, const struct timeval* t2) 
{
#ifndef S_SPLINT_S
        t1->tv_sec += t2->tv_sec;
        t1->tv_usec += t2->tv_usec;
        while(t1->tv_usec >= 1000000) {
                t1->tv_usec -= 1000000;
                t1->tv_sec++;
        }
#endif
}

/** timeval subtract, t1 -= t2 */
static void
dl_tv_subtract(struct timeval* t1, const struct timeval* t2) 
{
#ifndef S_SPLINT_S
        t1->tv_sec -= t2->tv_sec;
        if(t1->tv_usec >= t2->tv_usec) {
                t1->tv_usec -= t2->tv_usec;
        } else {
                t1->tv_sec--;
                t1->tv_usec = 1000000-(t2->tv_usec-t1->tv_usec);
        }
#endif
}


/** create new ring buffer */
static struct ringbuf*
ring_create(size_t sz)
{
        struct ringbuf* r = (struct ringbuf*)calloc(1, sizeof(*r));
        if(!r) fatal_exit("out of memory");
        r->buf = (uint8_t*)malloc(sz);
        if(!r->buf) fatal_exit("out of memory");
        r->size = sz;
        r->low = 0;
        r->high = 0;
        return r;
}

/** delete ring buffer */
static void
ring_delete(struct ringbuf* r)
{
        if(!r) return;
        free(r->buf);
        free(r);
}

/** add entry to ringbuffer */
static void
ring_add(struct ringbuf* r, sldns_buffer* pkt, struct timeval* now, 
        struct timeval* delay, struct proxy* p)
{
        /* time -- proxy* -- 16bitlen -- message */
        uint16_t len = (uint16_t)sldns_buffer_limit(pkt);
        struct timeval when;
        size_t needed;
        uint8_t* where = NULL;
        log_assert(sldns_buffer_limit(pkt) <= 65535);
        needed = sizeof(when) + sizeof(p) + sizeof(len) + len;
        /* put item into ringbuffer */
        if(r->low < r->high) {
                /* used part is in the middle */
                if(r->size - r->high >= needed) {
                        where = r->buf + r->high;
                        r->high += needed;
                } else if(r->low > needed) {
                        /* wrap around ringbuffer */
                        /* make sure r->low == r->high means empty */
                        /* so r->low == r->high cannot be used to signify
                         * a completely full ringbuf */
                        if(r->size - r->high > sizeof(when)+sizeof(p)) {
                                /* zero entry at end of buffer */
                                memset(r->buf+r->high, 0, 
                                        sizeof(when)+sizeof(p));
                        }
                        where = r->buf;
                        r->high = needed;
                } else {
                        /* drop message */
                        log_warn("warning: mem full, dropped message");
                        return;
                }
        } else {
                /* empty */
                if(r->high == r->low) {
                        where = r->buf;
                        r->low = 0;
                        r->high = needed;
                /* unused part is in the middle */
                /* so ringbuffer has wrapped around */
                } else if(r->low - r->high > needed) {
                        where = r->buf + r->high;
                        r->high += needed;
                } else {
                        log_warn("warning: mem full, dropped message");
                        return;
                }
        }
        when = *now;
        dl_tv_add(&when, delay);
        /* copy it at where part */
        log_assert(where != NULL);
        memmove(where, &when, sizeof(when));
        memmove(where+sizeof(when), &p, sizeof(p));
        memmove(where+sizeof(when)+sizeof(p), &len, sizeof(len));
        memmove(where+sizeof(when)+sizeof(p)+sizeof(len), 
                sldns_buffer_begin(pkt), len);
}

/** see if the ringbuffer is empty */
static int
ring_empty(struct ringbuf* r)
{
        return (r->low == r->high);
}

/** peek at timevalue for next item in ring */
static struct timeval*
ring_peek_time(struct ringbuf* r)
{
        if(ring_empty(r))
                return NULL;
        return (struct timeval*)&r->buf[r->low];
}

/** get entry from ringbuffer */
static int
ring_pop(struct ringbuf* r, sldns_buffer* pkt, struct timeval* tv, 
        struct proxy** p)
{
        /* time -- proxy* -- 16bitlen -- message */
        uint16_t len;
        uint8_t* where = NULL;
        size_t done;
        if(r->low == r->high)
                return 0;
        where = r->buf + r->low;
        memmove(tv, where, sizeof(*tv));
        memmove(p, where+sizeof(*tv), sizeof(*p));
        memmove(&len, where+sizeof(*tv)+sizeof(*p), sizeof(len));
        memmove(sldns_buffer_begin(pkt), 
                where+sizeof(*tv)+sizeof(*p)+sizeof(len), len);
        sldns_buffer_set_limit(pkt, (size_t)len);
        done = sizeof(*tv)+sizeof(*p)+sizeof(len)+len;
        /* move lowmark */
        if(r->low < r->high) {
                /* used part in middle */
                log_assert(r->high - r->low >= done);
                r->low += done;
        } else {
                /* unused part in middle */
                log_assert(r->size - r->low >= done);
                r->low += done;
                if(r->size - r->low > sizeof(*tv)+sizeof(*p)) {
                        /* see if it is zeroed; means end of buffer */
                        struct proxy* pz;
                        memmove(&pz, r->buf+r->low+sizeof(*tv), sizeof(pz));
                        if(pz == NULL)
                                r->low = 0;
                } else r->low = 0;
        }
        if(r->low == r->high) {
                r->low = 0; /* reset if empty */
                r->high = 0;
        }
        return 1;
}
        
/** signal handler global info */
static volatile int do_quit = 0;

/** signal handler for user quit */
static RETSIGTYPE delayer_sigh(int sig)
{
        char str[] = "exit on signal   \n";
        str[15] = '0' + (sig/10)%10;
        str[16] = '0' + sig%10;
        /* simple cast to void will not silence Wunused-result */
        (void)!write(STDOUT_FILENO, str, strlen(str));
        do_quit = 1;
}

/** send out waiting packets */
static void
service_send(struct ringbuf* ring, struct timeval* now, sldns_buffer* pkt,
        struct sockaddr_storage* srv_addr, socklen_t srv_len)
{
        struct proxy* p;
        struct timeval tv;
        ssize_t sent;
        while(!ring_empty(ring) && 
                dl_tv_smaller(ring_peek_time(ring), now)) {
                /* this items needs to be sent out */
                if(!ring_pop(ring, pkt, &tv, &p))
                        fatal_exit("ringbuf error: pop failed");
                verbose(1, "send out query %d.%6.6d", 
                        (unsigned)tv.tv_sec, (unsigned)tv.tv_usec);
                log_addr(1, "from client", &p->addr, p->addr_len);
                /* send it */
                sent = sendto(p->s, (void*)sldns_buffer_begin(pkt), 
                        sldns_buffer_limit(pkt), 0, 
                        (struct sockaddr*)srv_addr, srv_len);
                if(sent == -1) {
                        log_err("sendto: %s", sock_strerror(errno));
                } else if(sent != (ssize_t)sldns_buffer_limit(pkt)) {
                        log_err("sendto: partial send");
                }
                p->lastuse = *now;
                p->numsent++;
        }
}

/** do proxy for one readable client */
static void
do_proxy(struct proxy* p, int retsock, sldns_buffer* pkt)
{
        int i;
        ssize_t r;
        for(i=0; i<TRIES_PER_SELECT; i++) {
                r = recv(p->s, (void*)sldns_buffer_begin(pkt), 
                        sldns_buffer_capacity(pkt), 0);
                if(r == -1) {
#ifndef USE_WINSOCK
                        if(errno == EAGAIN || errno == EINTR)
                                return;
#else
                        if(WSAGetLastError() == WSAEINPROGRESS ||
                                WSAGetLastError() == WSAEWOULDBLOCK)
                                return;
#endif
                        log_err("recv: %s", sock_strerror(errno));
                        return;
                }
                sldns_buffer_set_limit(pkt, (size_t)r);
                log_addr(1, "return reply to client", &p->addr, p->addr_len);
                /* send reply back to the real client */
                p->numreturn++;
                r = sendto(retsock, (void*)sldns_buffer_begin(pkt), (size_t)r, 
                        0, (struct sockaddr*)&p->addr, p->addr_len);
                if(r == -1) {
                        log_err("sendto: %s", sock_strerror(errno));
                }
        }
}

/** proxy return replies to clients */
static void
service_proxy(fd_set* rset, int retsock, struct proxy* proxies, 
        sldns_buffer* pkt, struct timeval* now)
{
        struct proxy* p;
        for(p = proxies; p; p = p->next) {
                if(FD_ISSET(p->s, rset)) {
                        p->lastuse = *now;
                        do_proxy(p, retsock, pkt);
                }
        }
}

/** find or else create proxy for this remote client */
static struct proxy*
find_create_proxy(struct sockaddr_storage* from, socklen_t from_len,
        fd_set* rorig, int* max, struct proxy** proxies, int serv_ip6,
        struct timeval* now, struct timeval* reuse_timeout)
{
        struct proxy* p;
        struct timeval t;
        for(p = *proxies; p; p = p->next) {
                if(sockaddr_cmp(from, from_len, &p->addr, p->addr_len)==0)
                        return p;
        }
        /* possibly: reuse lapsed entries */
        for(p = *proxies; p; p = p->next) {
                if(p->numwait > p->numsent || p->numsent > p->numreturn)
                        continue;
                t = *now;
                dl_tv_subtract(&t, &p->lastuse);
                if(dl_tv_smaller(&t, reuse_timeout))
                        continue;
                /* yes! */
                verbose(1, "reuse existing entry");
                memmove(&p->addr, from, from_len);
                p->addr_len = from_len;
                p->numreuse++;
                return p;
        }
        /* create new */
        p = (struct proxy*)calloc(1, sizeof(*p));
        if(!p) fatal_exit("out of memory");
        p->s = socket(serv_ip6?AF_INET6:AF_INET, SOCK_DGRAM, 0);
        if(p->s == -1) {
                fatal_exit("socket: %s", sock_strerror(errno));
        }
        fd_set_nonblock(p->s);
        memmove(&p->addr, from, from_len);
        p->addr_len = from_len;
        p->next = *proxies;
        *proxies = p;
        FD_SET(FD_SET_T p->s, rorig);
        if(p->s+1 > *max)
                *max = p->s+1;
        return p;
}

/** recv new waiting packets */
static void
service_recv(int s, struct ringbuf* ring, sldns_buffer* pkt, 
        fd_set* rorig, int* max, struct proxy** proxies,
        struct sockaddr_storage* srv_addr, socklen_t srv_len, 
        struct timeval* now, struct timeval* delay, struct timeval* reuse)
{
        int i;
        struct sockaddr_storage from;
        socklen_t from_len;
        ssize_t len;
        struct proxy* p;
        for(i=0; i<TRIES_PER_SELECT; i++) {
                from_len = (socklen_t)sizeof(from);
                len = recvfrom(s, (void*)sldns_buffer_begin(pkt),
                        sldns_buffer_capacity(pkt), 0,
                        (struct sockaddr*)&from, &from_len);
                if(len < 0) {
#ifndef USE_WINSOCK
                        if(errno == EAGAIN || errno == EINTR)
                                return;
#else
                        if(WSAGetLastError() == WSAEWOULDBLOCK || 
                                WSAGetLastError() == WSAEINPROGRESS)
                                return;
#endif
                        fatal_exit("recvfrom: %s", sock_strerror(errno));
                }
                sldns_buffer_set_limit(pkt, (size_t)len);
                /* find its proxy element */
                p = find_create_proxy(&from, from_len, rorig, max, proxies,
                        addr_is_ip6(srv_addr, srv_len), now, reuse);
                if(!p) fatal_exit("error: cannot find or create proxy");
                p->lastuse = *now;
                ring_add(ring, pkt, now, delay, p);
                p->numwait++;
                log_addr(1, "recv from client", &p->addr, p->addr_len);
        }
}

/** delete tcp proxy */
static void
tcp_proxy_delete(struct tcp_proxy* p)
{
        struct tcp_send_list* s, *sn;
        if(!p)
                return;
        log_addr(1, "delete tcp proxy", &p->addr, p->addr_len);
        s = p->querylist;
        while(s) {
                sn = s->next;
                free(s->item);
                free(s);
                s = sn;
        }
        s = p->answerlist;
        while(s) {
                sn = s->next;
                free(s->item);
                free(s);
                s = sn;
        }
        sock_close(p->client_s);
        if(p->server_s != -1)
                sock_close(p->server_s);
        free(p);
}

/** accept new TCP connections, and set them up */
static void
service_tcp_listen(int s, fd_set* rorig, int* max, struct tcp_proxy** proxies,
        struct sockaddr_storage* srv_addr, socklen_t srv_len, 
        struct timeval* now, struct timeval* tcp_timeout)
{
        int newfd;
        struct sockaddr_storage addr;
        struct tcp_proxy* p;
        socklen_t addr_len;
        newfd = accept(s, (struct sockaddr*)&addr, &addr_len);
        if(newfd == -1) {
#ifndef USE_WINSOCK
                if(errno == EAGAIN || errno == EINTR)
                        return;
#else
                if(WSAGetLastError() == WSAEWOULDBLOCK || 
                        WSAGetLastError() == WSAEINPROGRESS ||
                        WSAGetLastError() == WSAECONNRESET)
                        return;
#endif
                fatal_exit("accept: %s", sock_strerror(errno));
        }
        p = (struct tcp_proxy*)calloc(1, sizeof(*p));
        if(!p) fatal_exit("out of memory");
        memmove(&p->addr, &addr, addr_len);
        p->addr_len = addr_len;
        log_addr(1, "new tcp proxy", &p->addr, p->addr_len);
        p->client_s = newfd;
        p->server_s = socket(addr_is_ip6(srv_addr, srv_len)?AF_INET6:AF_INET,
                SOCK_STREAM, 0);
        if(p->server_s == -1) {
                fatal_exit("tcp socket: %s", sock_strerror(errno));
        }
        fd_set_nonblock(p->client_s);
        fd_set_nonblock(p->server_s);
        if(connect(p->server_s, (struct sockaddr*)srv_addr, srv_len) == -1) {
#ifndef USE_WINSOCK
                if(errno != EINPROGRESS) {
                        log_err("tcp connect: %s", strerror(errno));
#else
                if(WSAGetLastError() != WSAEWOULDBLOCK &&
                        WSAGetLastError() != WSAEINPROGRESS) {
                        log_err("tcp connect: %s", 
                                wsa_strerror(WSAGetLastError()));
#endif
                        sock_close(p->server_s);
                        sock_close(p->client_s);
                        free(p);
                        return;
                }
        }
        p->timeout = *now;
        dl_tv_add(&p->timeout, tcp_timeout);

        /* listen to client and server */
        FD_SET(FD_SET_T p->client_s, rorig);
        FD_SET(FD_SET_T p->server_s, rorig);
        if(p->client_s+1 > *max)
                *max = p->client_s+1;
        if(p->server_s+1 > *max)
                *max = p->server_s+1;

        /* add into proxy list */
        p->next = *proxies;
        *proxies = p;
}

/** relay TCP, read a part */
static int
tcp_relay_read(int s, struct tcp_send_list** first, 
        struct tcp_send_list** last, struct timeval* now, 
        struct timeval* delay, sldns_buffer* pkt)
{
        struct tcp_send_list* item;
        ssize_t r = recv(s, (void*)sldns_buffer_begin(pkt), 
                sldns_buffer_capacity(pkt), 0);
        if(r == -1) {
#ifndef USE_WINSOCK
                if(errno == EINTR || errno == EAGAIN)
                        return 1;
#else
                if(WSAGetLastError() == WSAEINPROGRESS || 
                        WSAGetLastError() == WSAEWOULDBLOCK)
                        return 1;
#endif
                log_err("tcp read: %s", sock_strerror(errno));
                return 0;
        } else if(r == 0) {
                /* connection closed */
                return 0;
        }
        item = (struct tcp_send_list*)malloc(sizeof(*item));
        if(!item) {
                log_err("out of memory");
                return 0;
        }
        verbose(1, "read item len %d", (int)r);
        item->len = (size_t)r;
        item->item = memdup(sldns_buffer_begin(pkt), item->len);
        if(!item->item) {
                free(item);
                log_err("out of memory");
                return 0;
        }
        item->done = 0;
        item->wait = *now;
        dl_tv_add(&item->wait, delay);
        item->next = NULL;
        
        /* link in */
        if(*first) {
                (*last)->next = item;
        } else {
                *first = item;
        }
        *last = item;
        return 1;
}

/** relay TCP, write a part */
static int
tcp_relay_write(int s, struct tcp_send_list** first, 
        struct tcp_send_list** last, struct timeval* now)
{
        ssize_t r;
        struct tcp_send_list* p;
        while(*first) {
                p = *first;
                /* is the item ready? */
                if(!dl_tv_smaller(&p->wait, now))
                        return 1;
                /* write it */
                r = send(s, (void*)(p->item + p->done), p->len - p->done, 0);
                if(r == -1) {
#ifndef USE_WINSOCK
                        if(errno == EAGAIN || errno == EINTR)
                                return 1;
#else
                        if(WSAGetLastError() == WSAEWOULDBLOCK || 
                                WSAGetLastError() == WSAEINPROGRESS)
                                return 1;
#endif
                        log_err("tcp write: %s", sock_strerror(errno));
                        return 0;
                } else if(r == 0) {
                        /* closed */
                        return 0;
                }
                /* account it */
                p->done += (size_t)r;
                verbose(1, "write item %d of %d", (int)p->done, (int)p->len);
                if(p->done >= p->len) {
                        free(p->item);
                        *first = p->next;
                        if(!*first)
                                *last = NULL;
                        free(p);
                } else {
                        /* partial write */
                        return 1;
                }
        }
        return 1;
}

/** perform TCP relaying */
static void
service_tcp_relay(struct tcp_proxy** tcp_proxies, struct timeval* now,
        struct timeval* delay, struct timeval* tcp_timeout, sldns_buffer* pkt,
        fd_set* rset, fd_set* rorig, fd_set* worig)
{
        struct tcp_proxy* p, **prev;
        struct timeval tout;
        int delete_it;
        p = *tcp_proxies;
        prev = tcp_proxies;
        tout = *now;
        dl_tv_add(&tout, tcp_timeout);

        while(p) {
                delete_it = 0;
                /* can we receive further queries? */
                if(!delete_it && FD_ISSET(p->client_s, rset)) {
                        p->timeout = tout;
                        log_addr(1, "read tcp query", &p->addr, p->addr_len);
                        if(!tcp_relay_read(p->client_s, &p->querylist, 
                                &p->querylast, now, delay, pkt))
                                delete_it = 1;
                }
                /* can we receive further answers? */
                if(!delete_it && p->server_s != -1 &&
                        FD_ISSET(p->server_s, rset)) {
                        p->timeout = tout;
                        log_addr(1, "read tcp answer", &p->addr, p->addr_len);
                        if(!tcp_relay_read(p->server_s, &p->answerlist, 
                                &p->answerlast, now, delay, pkt)) {
                                sock_close(p->server_s);
                                FD_CLR(FD_SET_T p->server_s, worig);
                                FD_CLR(FD_SET_T p->server_s, rorig);
                                p->server_s = -1;
                        }
                }
                /* can we send on further queries */
                if(!delete_it && p->querylist && p->server_s != -1) {
                        p->timeout = tout;
                        if(dl_tv_smaller(&p->querylist->wait, now))
                                log_addr(1, "write tcp query", 
                                        &p->addr, p->addr_len);
                        if(!tcp_relay_write(p->server_s, &p->querylist, 
                                &p->querylast, now))
                                delete_it = 1;
                        if(p->querylist &&
                                dl_tv_smaller(&p->querylist->wait, now))
                                FD_SET(FD_SET_T p->server_s, worig);
                        else    FD_CLR(FD_SET_T p->server_s, worig);
                }

                /* can we send on further answers */
                if(!delete_it && p->answerlist) {
                        p->timeout = tout;
                        if(dl_tv_smaller(&p->answerlist->wait, now))
                                log_addr(1, "write tcp answer", 
                                        &p->addr, p->addr_len);
                        if(!tcp_relay_write(p->client_s, &p->answerlist, 
                                &p->answerlast, now))
                                delete_it = 1;
                        if(p->answerlist && dl_tv_smaller(&p->answerlist->wait,
                                now))
                                FD_SET(FD_SET_T p->client_s, worig);
                        else    FD_CLR(FD_SET_T p->client_s, worig);
                        if(!p->answerlist && p->server_s == -1)
                                delete_it = 1;
                }

                /* does this entry timeout? (unused too long) */
                if(dl_tv_smaller(&p->timeout, now)) {
                        delete_it = 1;
                }
                if(delete_it) {
                        struct tcp_proxy* np = p->next;
                        *prev = np;
                        FD_CLR(FD_SET_T p->client_s, rorig);
                        FD_CLR(FD_SET_T p->client_s, worig);
                        if(p->server_s != -1) {
                                FD_CLR(FD_SET_T p->server_s, rorig);
                                FD_CLR(FD_SET_T p->server_s, worig);
                        }
                        tcp_proxy_delete(p);
                        p = np;
                        continue;
                }

                prev = &p->next;
                p = p->next;
        }
}

/** find waiting time */
static int
service_findwait(struct timeval* now, struct timeval* wait, 
        struct ringbuf* ring, struct tcp_proxy* tcplist)
{
        /* first item is the time to wait */
        struct timeval* peek = ring_peek_time(ring);
        struct timeval tcv;
        int have_tcpval = 0;
        struct tcp_proxy* p;

        /* also for TCP list the first in sendlists is the time to wait */
        for(p=tcplist; p; p=p->next) {
                if(!have_tcpval)
                        tcv = p->timeout;
                have_tcpval = 1;
                if(dl_tv_smaller(&p->timeout, &tcv))
                        tcv = p->timeout;
                if(p->querylist && dl_tv_smaller(&p->querylist->wait, &tcv))
                        tcv = p->querylist->wait;
                if(p->answerlist && dl_tv_smaller(&p->answerlist->wait, &tcv))
                        tcv = p->answerlist->wait;
        }
        if(peek) {
                /* peek can be unaligned */
                /* use wait as a temp variable */
                memmove(wait, peek, sizeof(*wait));
                if(!have_tcpval)
                        tcv = *wait;
                else if(dl_tv_smaller(wait, &tcv))
                        tcv = *wait;
                have_tcpval = 1;
        }
        if(have_tcpval) {
                *wait = tcv;
                dl_tv_subtract(wait, now);
                return 1;
        }
        /* nothing, block */
        return 0;
}

/** clear proxy list */
static void
proxy_list_clear(struct proxy* p)
{
        char from[109];
        struct proxy* np;
        int i=0, port;
        while(p) {
                np = p->next;
                port = (int)ntohs(((struct sockaddr_in*)&p->addr)->sin_port);
                if(addr_is_ip6(&p->addr, p->addr_len)) {
                        if(inet_ntop(AF_INET6, 
                                &((struct sockaddr_in6*)&p->addr)->sin6_addr,
                                from, (socklen_t)sizeof(from)) == 0)
                                (void)strlcpy(from, "err", sizeof(from));
                } else {
                        if(inet_ntop(AF_INET, 
                                &((struct sockaddr_in*)&p->addr)->sin_addr,
                                from, (socklen_t)sizeof(from)) == 0)
                                (void)strlcpy(from, "err", sizeof(from));
                }
                printf("client[%d]: last %s@%d of %d : %u in, %u out, "
                        "%u returned\n", i++, from, port, (int)p->numreuse+1,
                        (unsigned)p->numwait, (unsigned)p->numsent, 
                        (unsigned)p->numreturn);
                sock_close(p->s);
                free(p);
                p = np;
        }
}

/** clear TCP proxy list */
static void
tcp_proxy_list_clear(struct tcp_proxy* p)
{
        struct tcp_proxy* np;
        while(p) {
                np = p->next;
                tcp_proxy_delete(p);
                p = np;
        }
}

/** delayer service loop */
static void
service_loop(int udp_s, int listen_s, struct ringbuf* ring, 
        struct timeval* delay, struct timeval* reuse,
        struct sockaddr_storage* srv_addr, socklen_t srv_len, 
        sldns_buffer* pkt)
{
        fd_set rset, rorig;
        fd_set wset, worig;
        struct timeval now, wait;
        int max, have_wait = 0;
        struct proxy* proxies = NULL;
        struct tcp_proxy* tcp_proxies = NULL;
        struct timeval tcp_timeout;
        tcp_timeout.tv_sec = 120;
        tcp_timeout.tv_usec = 0;
#ifndef S_SPLINT_S
        FD_ZERO(&rorig);
        FD_ZERO(&worig);
        FD_SET(FD_SET_T udp_s, &rorig);
        FD_SET(FD_SET_T listen_s, &rorig);
#endif
        max = udp_s + 1;
        if(listen_s + 1 > max) max = listen_s + 1;
        while(!do_quit) {
                /* wait for events */
                rset = rorig;
                wset = worig;
                if(have_wait)
                        verbose(1, "wait for %d.%6.6d",
                        (unsigned)wait.tv_sec, (unsigned)wait.tv_usec);
                else    verbose(1, "wait");
                if(select(max, &rset, &wset, NULL, have_wait?&wait:NULL) < 0) {
                        if(errno == EAGAIN || errno == EINTR)
                                continue;
                        fatal_exit("select: %s", strerror(errno));
                }
                /* get current time */
                if(gettimeofday(&now, NULL) < 0) {
                        if(errno == EAGAIN || errno == EINTR)
                                continue;
                        fatal_exit("gettimeofday: %s", strerror(errno));
                }
                verbose(1, "process at %u.%6.6u\n", 
                        (unsigned)now.tv_sec, (unsigned)now.tv_usec);
                /* sendout delayed queries to master server (frees up buffer)*/
                service_send(ring, &now, pkt, srv_addr, srv_len);
                /* proxy return replies */
                service_proxy(&rset, udp_s, proxies, pkt, &now);
                /* see what can be received to start waiting */
                service_recv(udp_s, ring, pkt, &rorig, &max, &proxies,
                        srv_addr, srv_len, &now, delay, reuse);
                /* see if there are new tcp connections */
                service_tcp_listen(listen_s, &rorig, &max, &tcp_proxies,
                        srv_addr, srv_len, &now, &tcp_timeout);
                /* service tcp connections */
                service_tcp_relay(&tcp_proxies, &now, delay, &tcp_timeout, 
                        pkt, &rset, &rorig, &worig);
                /* see what next timeout is (if any) */
                have_wait = service_findwait(&now, &wait, ring, tcp_proxies);
        }
        proxy_list_clear(proxies);
        tcp_proxy_list_clear(tcp_proxies);
}

/** delayer main service routine */
static void
service(const char* bind_str, int bindport, const char* serv_str, 
        size_t memsize, int delay_msec)
{
        struct sockaddr_storage bind_addr, srv_addr;
        socklen_t bind_len, srv_len;
        struct ringbuf* ring = ring_create(memsize);
        struct timeval delay, reuse;
        sldns_buffer* pkt;
        int i, s, listen_s;
#ifndef S_SPLINT_S
        delay.tv_sec = delay_msec / 1000;
        delay.tv_usec = (delay_msec % 1000)*1000;
#endif
        reuse = delay; /* reuse is max(4*delay, 1 second) */
        dl_tv_add(&reuse, &delay);
        dl_tv_add(&reuse, &delay);
        dl_tv_add(&reuse, &delay);
        if(reuse.tv_sec == 0)
                reuse.tv_sec = 1;
        if(!extstrtoaddr(serv_str, &srv_addr, &srv_len, UNBOUND_DNS_PORT)) {
                printf("cannot parse forward address: %s\n", serv_str);
                exit(1);
        }
        pkt = sldns_buffer_new(65535);
        if(!pkt)
                fatal_exit("out of memory");
        if( signal(SIGINT, delayer_sigh) == SIG_ERR ||
#ifdef SIGHUP
                signal(SIGHUP, delayer_sigh) == SIG_ERR ||
#endif
#ifdef SIGQUIT
                signal(SIGQUIT, delayer_sigh) == SIG_ERR ||
#endif
#ifdef SIGBREAK
                signal(SIGBREAK, delayer_sigh) == SIG_ERR ||
#endif
#ifdef SIGALRM
                signal(SIGALRM, delayer_sigh) == SIG_ERR ||
#endif
                signal(SIGTERM, delayer_sigh) == SIG_ERR)
                fatal_exit("could not bind to signal");
        /* bind UDP port */
        if((s = socket(str_is_ip6(bind_str)?AF_INET6:AF_INET,
                SOCK_DGRAM, 0)) == -1) {
                fatal_exit("socket: %s", sock_strerror(errno));
        }
        i=0;
        if(bindport == 0) {
                bindport = 1024 + ((int)arc4random())%64000;
                i = 100;
        }
        while(1) {
                if(!ipstrtoaddr(bind_str, bindport, &bind_addr, &bind_len)) {
                        printf("cannot parse listen address: %s\n", bind_str);
                        exit(1);
                }
                if(bind(s, (struct sockaddr*)&bind_addr, bind_len) == -1) {
                        log_err("bind: %s", sock_strerror(errno));
                        if(i--==0)
                                fatal_exit("cannot bind any port");
                        bindport = 1024 + ((int)arc4random())%64000;
                } else break;
        }
        fd_set_nonblock(s);
        /* and TCP port */
        if((listen_s = socket(str_is_ip6(bind_str)?AF_INET6:AF_INET,
                SOCK_STREAM, 0)) == -1) {
                fatal_exit("tcp socket: %s", sock_strerror(errno));
        }
#ifdef SO_REUSEADDR
        if(1) {
                int on = 1;
                if(setsockopt(listen_s, SOL_SOCKET, SO_REUSEADDR, (void*)&on,
                        (socklen_t)sizeof(on)) < 0)
                        fatal_exit("setsockopt(.. SO_REUSEADDR ..) failed: %s",
                                sock_strerror(errno));
        }
#endif
        if(bind(listen_s, (struct sockaddr*)&bind_addr, bind_len) == -1) {
                fatal_exit("tcp bind: %s", sock_strerror(errno));
        }
        if(listen(listen_s, 5) == -1) {
                fatal_exit("tcp listen: %s", sock_strerror(errno));
        }
        fd_set_nonblock(listen_s);
        printf("listening on port: %d\n", bindport);

        /* process loop */
        do_quit = 0;
        service_loop(s, listen_s, ring, &delay, &reuse, &srv_addr, srv_len, 
                pkt);

        /* cleanup */
        verbose(1, "cleanup");
        sock_close(s);
        sock_close(listen_s);
        sldns_buffer_free(pkt);
        ring_delete(ring);
}

/** getopt global, in case header files fail to declare it. */
extern int optind;
/** getopt global, in case header files fail to declare it. */
extern char* optarg;

/** main program for delayer */
int main(int argc, char** argv) 
{
        int c;          /* defaults */
        const char* server = "127.0.0.1@53";
        const char* bindto = "0.0.0.0";
        int bindport = 0;
        size_t memsize = 10*1024*1024;
        int delay = 100;

        verbosity = 0;
        log_init(0, 0, 0);
        log_ident_set("delayer");
        if(argc == 1) usage(argv);
        while( (c=getopt(argc, argv, "b:d:f:hm:p:")) != -1) {
                switch(c) {
                        case 'b':
                                bindto = optarg;
                                break;
                        case 'd':
                                if(atoi(optarg)==0 && strcmp(optarg,"0")!=0) {
                                        printf("bad delay: %s\n", optarg);
                                        return 1;
                                }
                                delay = atoi(optarg);
                                break;
                        case 'f':
                                server = optarg;
                                break;
                        case 'm':
                                if(!cfg_parse_memsize(optarg, &memsize)) {
                                        printf("bad memsize: %s\n", optarg);
                                        return 1;
                                }
                                break;
                        case 'p':
                                if(atoi(optarg)==0 && strcmp(optarg,"0")!=0) {
                                        printf("bad port nr: %s\n", optarg);
                                        return 1;
                                }
                                bindport = atoi(optarg);
                                break;
                        case 'h':
                        case '?':
                        default:
                                usage(argv);
                }
        }
        argc -= optind;
        argv += optind;
        if(argc != 0)
                usage(argv);

        printf("bind to %s @ %d and forward to %s after %d msec\n", 
                bindto, bindport, server, delay);
        service(bindto, bindport, server, memsize, delay);
        return 0;
}