# Cppcheck report - LibreOffice: sd/source/ui/remotecontrol/mDNSResponder/dnssd_clientlib.c

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    /* -*- Mode: C; tab-width: 4 -*-
     *
     * Copyright (c) 2004, Apple Computer, Inc. All rights reserved.
     *
     * Redistribution and use in source and binary forms, with or without
     * modification, are permitted provided that the following conditions are met:
     *
     * 1.  Redistributions of source code must retain the above copyright notice,
     *     this list of conditions and the following disclaimer.
     * 2.  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.
     * 3.  Neither the name of Apple Computer, Inc. ("Apple") 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 APPLE AND ITS 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 APPLE OR ITS 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.
     */

    #include <stdlib.h>
    #include <string.h>

    #include "dns_sd.h"

    #if MDNS_BUILDINGSHAREDLIBRARY || MDNS_BUILDINGSTUBLIBRARY
    #pragma export on
    #endif

    #if defined(_WIN32)
    // disable warning "conversion from <data> to uint16_t"
    #pragma warning(disable:4244)
    #define strncasecmp _strnicmp
    #define strcasecmp _stricmp
    #endif

    /*********************************************************************************************
    *
    *  Supporting Functions
    *
    *********************************************************************************************/

    #define mDNSIsDigit(X)     ((X) >= '0' && (X) <= '9')

    // DomainEndsInDot returns 1 if name ends with a dot, 0 otherwise
    // (DNSServiceConstructFullName depends this returning 1 for true, rather than any non-zero value meaning true)

    static int DomainEndsInDot(const char *dom)
    {
        while (dom[0] && dom[1])
        {
            if (dom[0] == '\\') // advance past escaped byte sequence
            {
                if (mDNSIsDigit(dom[1]) && mDNSIsDigit(dom[2]) && mDNSIsDigit(dom[3]))
                    dom += 4;           // If "\ddd"    then skip four
                else dom += 2;          // else if "\x" then skip two
            }
            else dom++;                 // else goto next character
        }
        return (dom[0] == '.');
    }

    static uint8_t *InternalTXTRecordSearch
    (
        uint16_t txtLen,
        const void       *txtRecord,
        const char       *key,
        unsigned long    *keylen
    )
    {
        uint8_t *p = (uint8_t*)txtRecord;
        uint8_t *e = p + txtLen;
        *keylen = (unsigned long) strlen(key);
        while (p<e)
        {
            uint8_t *x = p;
            p += 1 + p[0];
            if (p <= e && *keylen <= x[0] && !strncasecmp(key, (char*)x+1, *keylen))
                if (*keylen == x[0] || x[1+*keylen] == '=') return(x);
        }
        return(NULL);
    }

    /*********************************************************************************************
    *
    *  General Utility Functions
    *
    *********************************************************************************************/

    // Note: Need to make sure we don't write more than kDNSServiceMaxDomainName (1009) bytes to fullName
    // In earlier builds this constant was defined to be 1005, so to avoid buffer overruns on clients
    // compiled with that constant we'll actually limit the output to 1005 bytes.

    DNSServiceErrorType DNSSD_API DNSServiceConstructFullName<--- The function 'DNSServiceConstructFullName' is never used.
    (
        char       *const fullName,
        const char *const service,      // May be NULL
        const char *const regtype,
        const char *const domain
    )
    {
        const size_t len = !regtype ? 0 : strlen(regtype) - DomainEndsInDot(regtype);
        char       *fn   = fullName;
        char *const lim  = fullName + 1005;
        const char *s    = service;
        const char *r    = regtype;
        const char *d    = domain;

        // regtype must be at least "x._udp" or "x._tcp"
        if (len < 6 || !domain || !domain[0]) return kDNSServiceErr_BadParam;
        if (strncasecmp((regtype + len - 4), "_tcp", 4) && strncasecmp((regtype + len - 4), "_udp", 4)) return kDNSServiceErr_BadParam;

        if (service && *service)
        {
            while (*s)
            {
                unsigned char c = *s++;             // Needs to be unsigned, or values like 0xFF will be interpreted as < 32
                if (c <= ' ')                       // Escape non-printable characters
                {
                    if (fn+4 >= lim) goto fail;
                    *fn++ = '\\';
                    *fn++ = '0' + (c / 100);
                    *fn++ = '0' + (c /  10) % 10;
                    c     = '0' + (c      ) % 10;
                }
                else if (c == '.' || (c == '\\'))   // Escape dot and backslash literals
                {
                    if (fn+2 >= lim) goto fail;
                    *fn++ = '\\';
                }
                else
                if (fn+1 >= lim) goto fail;
                *fn++ = (char)c;
            }
            *fn++ = '.';
        }

        while (*r) if (fn+1 >= lim) goto fail;else *fn++ = *r++;
        if (!DomainEndsInDot(regtype)) { if (fn+1 >= lim) goto fail;else *fn++ = '.';}

        while (*d) if (fn+1 >= lim) goto fail;else *fn++ = *d++;
        if (!DomainEndsInDot(domain)) { if (fn+1 >= lim) goto fail;else *fn++ = '.';}

        *fn = '\0';
        return kDNSServiceErr_NoError;

    fail:
        *fn = '\0';
        return kDNSServiceErr_BadParam;
    }

    /*********************************************************************************************
    *
    *   TXT Record Construction Functions
    *
    *********************************************************************************************/

    typedef struct _TXTRecordRefRealType
    {
        uint8_t  *buffer;       // Pointer to data
        uint16_t buflen;        // Length of buffer
        uint16_t datalen;       // Length currently in use
        uint16_t malloced;  // Non-zero if buffer was allocated via malloc()
    } TXTRecordRefRealType;

    #define txtRec ((TXTRecordRefRealType*)txtRecord)

    // The opaque storage defined in the public dns_sd.h header is 16 bytes;
    // make sure we don't exceed that.
    struct CompileTimeAssertionCheck_dnssd_clientlib
    {
        char assert0[(sizeof(TXTRecordRefRealType) <= 16) ? 1 : -1];
    };

    void DNSSD_API TXTRecordCreate<--- The function 'TXTRecordCreate' is never used.
    (
        TXTRecordRef     *txtRecord,
        uint16_t bufferLen,
        void             *buffer
    )
    {
        txtRec->buffer   = buffer;
        txtRec->buflen   = buffer ? bufferLen : (uint16_t)0;
        txtRec->datalen  = 0;
        txtRec->malloced = 0;
    }

    void DNSSD_API TXTRecordDeallocate(TXTRecordRef *txtRecord)<--- The function 'TXTRecordDeallocate' is never used.
    {
        if (txtRec->malloced) free(txtRec->buffer);
    }

    DNSServiceErrorType DNSSD_API TXTRecordSetValue<--- The function 'TXTRecordSetValue' is never used.
    (
        TXTRecordRef     *txtRecord,
        const char       *key,
        uint8_t valueSize,
        const void       *value
    )
    {
        uint8_t *start, *p;
        const char *k;
        unsigned long keysize, keyvalsize;

        for (k = key; *k; k++) if (*k < 0x20 || *k > 0x7E || *k == '=') return(kDNSServiceErr_Invalid);
        keysize = (unsigned long)(k - key);
        keyvalsize = 1 + keysize + (value ? (1 + valueSize) : 0);
        if (keysize < 1 || keyvalsize > 255) return(kDNSServiceErr_Invalid);
        (void)TXTRecordRemoveValue(txtRecord, key);
        if (txtRec->datalen + keyvalsize > txtRec->buflen)
        {
            unsigned char *newbuf;
            unsigned long newlen = txtRec->datalen + keyvalsize;
            if (newlen > 0xFFFF) return(kDNSServiceErr_Invalid);
            newbuf = malloc((size_t)newlen);
            if (!newbuf) return(kDNSServiceErr_NoMemory);
            memcpy(newbuf, txtRec->buffer, txtRec->datalen);
            if (txtRec->malloced) free(txtRec->buffer);
            txtRec->buffer = newbuf;
            txtRec->buflen = (uint16_t)(newlen);
            txtRec->malloced = 1;
        }
        start = txtRec->buffer + txtRec->datalen;
        p = start + 1;
        memcpy(p, key, keysize);
        p += keysize;
        if (value)
        {
            *p++ = '=';
            memcpy(p, value, valueSize);
            p += valueSize;
        }
        *start = (uint8_t)(p - start - 1);
        txtRec->datalen += p - start;
        return(kDNSServiceErr_NoError);
    }

    DNSServiceErrorType DNSSD_API TXTRecordRemoveValue
    (
        TXTRecordRef     *txtRecord,
        const char       *key
    )
    {
        unsigned long keylen, itemlen, remainder;
        uint8_t *item = InternalTXTRecordSearch(txtRec->datalen, txtRec->buffer, key, &keylen);
        if (!item) return(kDNSServiceErr_NoSuchKey);
        itemlen   = (unsigned long)(1 + item[0]);
        remainder = (unsigned long)((txtRec->buffer + txtRec->datalen) - (item + itemlen));
        // Use memmove because memcpy behaviour is undefined for overlapping regions
        memmove(item, item + itemlen, remainder);
        txtRec->datalen -= itemlen;
        return(kDNSServiceErr_NoError);
    }

    uint16_t DNSSD_API TXTRecordGetLength  (const TXTRecordRef *txtRecord) { return(txtRec->datalen); }<--- The function 'TXTRecordGetLength' is never used.
    const void * DNSSD_API TXTRecordGetBytesPtr(const TXTRecordRef *txtRecord) { return(txtRec->buffer); }<--- The function 'TXTRecordGetBytesPtr' is never used.

    /*********************************************************************************************
    *
    *   TXT Record Parsing Functions
    *
    *********************************************************************************************/

    int DNSSD_API TXTRecordContainsKey<--- The function 'TXTRecordContainsKey' is never used.
    (
        uint16_t txtLen,
        const void       *txtRecord,
        const char       *key
    )
    {
        unsigned long keylen;
        return (InternalTXTRecordSearch(txtLen, txtRecord, key, &keylen) ? 1 : 0);
    }

    const void * DNSSD_API TXTRecordGetValuePtr<--- The function 'TXTRecordGetValuePtr' is never used.
    (
        uint16_t txtLen,
        const void       *txtRecord,
        const char       *key,
        uint8_t          *valueLen
    )
    {
        unsigned long keylen;
        uint8_t *item = InternalTXTRecordSearch(txtLen, txtRecord, key, &keylen);
        if (!item || item[0] <= keylen) return(NULL);   // If key not found, or found with no value, return NULL
        *valueLen = (uint8_t)(item[0] - (keylen + 1));
        return (item + 1 + keylen + 1);
    }

    uint16_t DNSSD_API TXTRecordGetCount<--- The function 'TXTRecordGetCount' is never used.
    (
        uint16_t txtLen,
        const void       *txtRecord
    )
    {
        uint16_t count = 0;
        uint8_t *p = (uint8_t*)txtRecord;
        uint8_t *e = p + txtLen;
        while (p<e) { p += 1 + p[0]; count++; }
        return((p>e) ? (uint16_t)0 : count);
    }

    DNSServiceErrorType DNSSD_API TXTRecordGetItemAtIndex<--- The function 'TXTRecordGetItemAtIndex' is never used.
    (
        uint16_t txtLen,
        const void       *txtRecord,
        uint16_t itemIndex,
        uint16_t keyBufLen,
        char             *key,
        uint8_t          *valueLen,
        const void       **value
    )
    {
        uint16_t count = 0;
        uint8_t *p = (uint8_t*)txtRecord;
        uint8_t *e = p + txtLen;
        while (p<e && count<itemIndex) { p += 1 + p[0]; count++; }  // Find requested item
        if (p<e && p + 1 + p[0] <= e)   // If valid
        {
            uint8_t *x = p+1;
            unsigned long len = 0;
            e = p + 1 + p[0];
            while (x+len<e && x[len] != '=') len++;
            if (len >= keyBufLen) return(kDNSServiceErr_NoMemory);
            memcpy(key, x, len);
            key[len] = 0;
            if (x+len<e)        // If we found '='
            {
                *value = x + len + 1;
                *valueLen = (uint8_t)(p[0] - (len + 1));
            }
            else
            {
                *value = NULL;
                *valueLen = 0;
            }
            return(kDNSServiceErr_NoError);
        }
        return(kDNSServiceErr_Invalid);
    }

    /*********************************************************************************************
    *
    *   SCCS-compatible version string
    *
    *********************************************************************************************/

    // For convenience when using the "strings" command, this is the last thing in the file

    // Note: The C preprocessor stringify operator ('#') makes a string from its argument, without macro expansion
    // e.g. If "version" is #define'd to be "4", then STRINGIFY_AWE(version) will return the string "version", not "4"
    // To expand "version" to its value before making the string, use STRINGIFY(version) instead
    #define STRINGIFY_ARGUMENT_WITHOUT_EXPANSION(s) # s
    #define STRINGIFY(s) STRINGIFY_ARGUMENT_WITHOUT_EXPANSION(s)

    // NOT static -- otherwise the compiler may optimize it out
    // The "@(#) " pattern is a special prefix the "what" command looks for
    const char VersionString_SCCS_libdnssd[] = "@(#) libdns_sd " STRINGIFY(mDNSResponderVersion) " (" __DATE__ " " __TIME__ ")";