/* -*- Mode: C; tab-width: 4 -*-
 *
 * Copyright (c) 2004-2015 Apple Inc. All rights reserved.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

#include <stdio.h>              // Needed for fopen() etc.
#include <unistd.h>             // Needed for close()
#include <string.h>             // Needed for strlen() etc.
#include <errno.h>              // Needed for errno etc.
#include <sys/socket.h>         // Needed for socket() etc.
#include <netinet/in.h>         // Needed for sockaddr_in
#include <syslog.h>

#if APPLE_OSX_mDNSResponder
#include <os/log.h>
#endif 

#include "mDNSEmbeddedAPI.h"    // Defines the interface provided to the client layer above
#include "DNSCommon.h"
#include "PlatformCommon.h"

#ifdef NOT_HAVE_SOCKLEN_T
typedef unsigned int socklen_t;
#endif

// Bind a UDP socket to find the source address to a destination
mDNSexport void mDNSPlatformSourceAddrForDest(mDNSAddr *const src, const mDNSAddr *const dst)
{
    union { struct sockaddr s; struct sockaddr_in a4; struct sockaddr_in6 a6; } addr;
    socklen_t len = sizeof(addr);
    socklen_t inner_len = 0;
    int sock = socket(AF_INET, SOCK_DGRAM, 0);
    src->type = mDNSAddrType_None;
    if (sock == -1) return;
    if (dst->type == mDNSAddrType_IPv4)
    {
        inner_len = sizeof(addr.a4);
        #ifndef NOT_HAVE_SA_LEN
        addr.a4.sin_len         = inner_len;
        #endif
        addr.a4.sin_family      = AF_INET;
        addr.a4.sin_port        = 1;    // Not important, any port will do
        addr.a4.sin_addr.s_addr = dst->ip.v4.NotAnInteger;
    }
    else if (dst->type == mDNSAddrType_IPv6)
    {
        inner_len = sizeof(addr.a6);
        #ifndef NOT_HAVE_SA_LEN
        addr.a6.sin6_len      = inner_len;
        #endif
        addr.a6.sin6_family   = AF_INET6;
        addr.a6.sin6_flowinfo = 0;
        addr.a6.sin6_port     = 1;  // Not important, any port will do
        addr.a6.sin6_addr     = *(struct in6_addr*)&dst->ip.v6;
        addr.a6.sin6_scope_id = 0;
    }
    else return;

    if ((connect(sock, &addr.s, inner_len)) < 0)
    { LogMsg("mDNSPlatformSourceAddrForDest: connect %#a failed errno %d (%s)", dst, errno, strerror(errno)); goto exit; }

    if ((getsockname(sock, &addr.s, &len)) < 0)
    { LogMsg("mDNSPlatformSourceAddrForDest: getsockname failed errno %d (%s)", errno, strerror(errno)); goto exit; }

    src->type = dst->type;
    if (dst->type == mDNSAddrType_IPv4) src->ip.v4.NotAnInteger = addr.a4.sin_addr.s_addr;
    else src->ip.v6 = *(mDNSv6Addr*)&addr.a6.sin6_addr;
exit:
    close(sock);
}

// dst must be at least MAX_ESCAPED_DOMAIN_NAME bytes, and option must be less than 32 bytes in length
mDNSlocal mDNSBool GetConfigOption(char *dst, const char *option, FILE *f)
{
    char buf[32+1+MAX_ESCAPED_DOMAIN_NAME]; // Option name, one space, option value
    unsigned int len = strlen(option);
    if (len + 1 + MAX_ESCAPED_DOMAIN_NAME > sizeof(buf)-1) { LogMsg("GetConfigOption: option %s too long", option); return mDNSfalse; }
    fseek(f, 0, SEEK_SET);  // set position to beginning of stream
    while (fgets(buf, sizeof(buf), f))      // Read at most sizeof(buf)-1 bytes from file, and append '\0' C-string terminator
    {
        if (!strncmp(buf, option, len))
        {
            strncpy(dst, buf + len + 1, MAX_ESCAPED_DOMAIN_NAME-1);
            if (dst[MAX_ESCAPED_DOMAIN_NAME-1]) dst[MAX_ESCAPED_DOMAIN_NAME-1] = '\0';
            len = strlen(dst);
            if (len && dst[len-1] == '\n') dst[len-1] = '\0';  // chop newline
            return mDNStrue;
        }
    }
    debugf("Option %s not set", option);
    return mDNSfalse;
}

mDNSexport void ReadDDNSSettingsFromConfFile(mDNS *const m, const char *const filename, domainname *const hostname, domainname *const domain, mDNSBool *DomainDiscoveryDisabled)
{
    char buf[MAX_ESCAPED_DOMAIN_NAME] = "";
    mStatus err;
    FILE *f = fopen(filename, "r");

    if (hostname) hostname->c[0] = 0;
    if (domain) domain->c[0] = 0;
    if (DomainDiscoveryDisabled) *DomainDiscoveryDisabled = mDNSfalse;

    if (f)
    {
        if (DomainDiscoveryDisabled && GetConfigOption(buf, "DomainDiscoveryDisabled", f) && !strcasecmp(buf, "true")) *DomainDiscoveryDisabled = mDNStrue;
        if (hostname && GetConfigOption(buf, "hostname", f) && !MakeDomainNameFromDNSNameString(hostname, buf)) goto badf;
        if (domain && GetConfigOption(buf, "zone", f) && !MakeDomainNameFromDNSNameString(domain, buf)) goto badf;
        buf[0] = 0;
        GetConfigOption(buf, "secret-64", f);  // failure means no authentication
        fclose(f);
        f = NULL;
    }
    else
    {
        if (errno != ENOENT) LogMsg("ERROR: Config file exists, but cannot be opened.");
        return;
    }

    if (domain && domain->c[0] && buf[0])
    {
        DomainAuthInfo *info = (DomainAuthInfo*)mDNSPlatformMemAllocate(sizeof(*info));
        // for now we assume keyname = service reg domain and we use same key for service and hostname registration
        err = mDNS_SetSecretForDomain(m, info, domain, domain, buf, NULL, 0, mDNSfalse);
        if (err) LogMsg("ERROR: mDNS_SetSecretForDomain returned %d for domain %##s", err, domain->c);
    }

    return;

badf:
    LogMsg("ERROR: malformatted config file");
    if (f) fclose(f);
}

#if MDNS_DEBUGMSGS
mDNSexport void mDNSPlatformWriteDebugMsg(const char *msg)
{
    fprintf(stderr,"%s\n", msg);
    fflush(stderr);
}
#endif

mDNSexport void mDNSPlatformWriteLogMsg(const char *ident, const char *buffer, mDNSLogLevel_t loglevel)
{
#if APPLE_OSX_mDNSResponder && LogTimeStamps
    extern mDNS mDNSStorage;
    extern mDNSu32 mDNSPlatformClockDivisor;
    mDNSs32 t = mDNSStorage.timenow ? mDNSStorage.timenow : mDNSPlatformClockDivisor ? mDNS_TimeNow_NoLock(&mDNSStorage) : 0;
    int ms = ((t < 0) ? -t : t) % 1000;
#endif

    if (mDNS_DebugMode) // In debug mode we write to stderr
    {
#if APPLE_OSX_mDNSResponder && LogTimeStamps
        if (ident && ident[0] && mDNSPlatformClockDivisor)
            fprintf(stderr,"%8d.%03d: %s\n", (int)(t/1000), ms, buffer);
        else
#endif
        fprintf(stderr,"%s\n", buffer);
        fflush(stderr);
    }
    else                // else, in production mode, we write to syslog
    {
        static int log_inited = 0;

        int syslog_level = LOG_ERR;
        switch (loglevel)
        {
#if APPLE_OSX_mDNSResponder
        case MDNS_LOG_MSG:       syslog_level = OS_LOG_TYPE_DEFAULT;     break;
        case MDNS_LOG_OPERATION: syslog_level = OS_LOG_TYPE_INFO;        break;
        case MDNS_LOG_SPS:       syslog_level = OS_LOG_TYPE_INFO;        break;
        case MDNS_LOG_INFO:      syslog_level = OS_LOG_TYPE_INFO;        break;
        case MDNS_LOG_DEBUG:     syslog_level = OS_LOG_TYPE_DEBUG;       break;
        default:                 syslog_level = OS_LOG_TYPE_DEFAULT;     break;
#else
        case MDNS_LOG_MSG:       syslog_level = LOG_ERR;     break;
        case MDNS_LOG_OPERATION: syslog_level = LOG_WARNING; break;
        case MDNS_LOG_SPS:       syslog_level = LOG_NOTICE;  break;
        case MDNS_LOG_INFO:      syslog_level = LOG_INFO;    break;
        case MDNS_LOG_DEBUG:     syslog_level = LOG_DEBUG;   break;
        default:
            fprintf(stderr, "Unknown loglevel %d, assuming LOG_ERR\n", loglevel);
            fflush(stderr);
#endif
        }

        if (!log_inited) { openlog(ident, LOG_CONS, LOG_DAEMON); log_inited++; }

#if APPLE_OSX_mDNSResponder && LogTimeStamps
        if (ident && ident[0] && mDNSPlatformClockDivisor)
            syslog(syslog_level, "%8d.%03d: %s", (int)(t/1000), ms, buffer);
        else
#endif
        {
#if APPLE_OSX_mDNSResponder
            mDNSPlatformLogToFile(syslog_level, buffer);
#else
            syslog(syslog_level, "%s", buffer);
#endif
        }
    }
}
