initial commit, 4.5 stable

thirdparty/icu4c/common/uidna.cpp

@@ -0,0 +1,924 @@
+// © 2016 and later: Unicode, Inc. and others.
+// License & terms of use: http://www.unicode.org/copyright.html
+/*
+ *******************************************************************************
+ *
+ *   Copyright (C) 2003-2014, International Business Machines
+ *   Corporation and others.  All Rights Reserved.
+ *
+ *******************************************************************************
+ *   file name:  uidna.cpp
+ *   encoding:   UTF-8
+ *   tab size:   8 (not used)
+ *   indentation:4
+ *
+ *   created on: 2003feb1
+ *   created by: Ram Viswanadha
+ */
+
+#include "unicode/utypes.h"
+
+#if !UCONFIG_NO_IDNA
+
+#include "unicode/uidna.h"
+#include "unicode/ustring.h"
+#include "unicode/usprep.h"
+#include "punycode.h"
+#include "ustr_imp.h"
+#include "cmemory.h"
+#include "uassert.h"
+#include "sprpimpl.h"
+
+/* it is official IDNA ACE Prefix is "xn--" */
+static const char16_t ACE_PREFIX[] ={ 0x0078,0x006E,0x002d,0x002d } ;
+#define ACE_PREFIX_LENGTH 4
+
+#define MAX_LABEL_LENGTH 63
+/* The Max length of the labels should not be more than MAX_LABEL_LENGTH */
+#define MAX_LABEL_BUFFER_SIZE 100
+
+#define MAX_DOMAIN_NAME_LENGTH 255
+/* The Max length of the domain names should not be more than MAX_DOMAIN_NAME_LENGTH */
+#define MAX_IDN_BUFFER_SIZE   MAX_DOMAIN_NAME_LENGTH+1
+
+#define LOWER_CASE_DELTA 0x0020
+#define HYPHEN           0x002D
+#define FULL_STOP        0x002E
+#define CAPITAL_A        0x0041
+#define CAPITAL_Z        0x005A
+
+inline static char16_t
+toASCIILower(char16_t ch){
+    if(CAPITAL_A <= ch && ch <= CAPITAL_Z){
+        return ch + LOWER_CASE_DELTA;
+    }
+    return ch;
+}
+
+inline static UBool 
+startsWithPrefix(const char16_t* src , int32_t srcLength){
+    if(srcLength < ACE_PREFIX_LENGTH){
+        return false;
+    }
+
+    for(int8_t i=0; i< ACE_PREFIX_LENGTH; i++){
+        if(toASCIILower(src[i]) != ACE_PREFIX[i]){
+            return false;
+        }
+    }
+    return true;
+}
+
+
+inline static int32_t
+compareCaseInsensitiveASCII(const char16_t* s1, int32_t s1Len,
+                            const char16_t* s2, int32_t s2Len){
+    
+    int32_t minLength;
+    int32_t lengthResult;
+
+    // are we comparing different lengths?
+    if(s1Len != s2Len) {
+        if(s1Len < s2Len) {
+            minLength = s1Len;
+            lengthResult = -1;
+        } else {
+            minLength = s2Len;
+            lengthResult = 1;
+        }
+    } else {
+        // ok the lengths are equal
+        minLength = s1Len;
+        lengthResult = 0;
+    }
+
+    char16_t c1,c2;
+    int32_t rc;
+
+    for(int32_t i =0;/* no condition */;i++) {
+
+        /* If we reach the ends of both strings then they match */
+        if(i == minLength) {
+            return lengthResult;
+        }
+        
+        c1 = s1[i];
+        c2 = s2[i];
+        
+        /* Case-insensitive comparison */
+        if(c1!=c2) {
+            rc = static_cast<int32_t>(toASCIILower(c1)) - static_cast<int32_t>(toASCIILower(c2));
+            if(rc!=0) {
+                lengthResult=rc;
+                break;
+            }
+        }
+    }
+    return lengthResult;
+}
+
+
+/**
+ * Ascertain if the given code point is a label separator as 
+ * defined by the IDNA RFC
+ * 
+ * @param ch The code point to be ascertained
+ * @return true if the char is a label separator
+ * @stable ICU 2.8
+ */
+static inline UBool isLabelSeparator(char16_t ch){
+    switch(ch){
+        case 0x002e:
+        case 0x3002:
+        case 0xFF0E:
+        case 0xFF61:
+            return true;
+        default:
+            return false;           
+    }
+}
+
+// returns the length of the label excluding the separator
+// if *limit == separator then the length returned does not include 
+// the separtor.
+static inline int32_t
+getNextSeparator(char16_t *src, int32_t srcLength,
+                 char16_t **limit, UBool *done){
+    if(srcLength == -1){
+        int32_t i;
+        for(i=0 ; ;i++){
+            if(src[i] == 0){
+                *limit = src + i; // point to null
+                *done = true;
+                return i;
+            }
+            if(isLabelSeparator(src[i])){
+                *limit = src + (i+1); // go past the delimiter
+                return i;
+                
+            }
+        }
+    }else{
+        int32_t i;
+        for(i=0;i<srcLength;i++){
+            if(isLabelSeparator(src[i])){
+                *limit = src + (i+1); // go past the delimiter
+                return i;
+            }
+        }
+        // we have not found the delimiter
+        // if(i==srcLength)
+        *limit = src+srcLength;
+        *done = true;
+
+        return i;
+    }
+}
+static inline UBool isLDHChar(char16_t ch){
+    // high runner case
+    if(ch>0x007A){
+        return false;
+    }
+    //[\\u002D \\u0030-\\u0039 \\u0041-\\u005A \\u0061-\\u007A]
+    if( (ch==0x002D) || 
+        (0x0030 <= ch && ch <= 0x0039) ||
+        (0x0041 <= ch && ch <= 0x005A) ||
+        (0x0061 <= ch && ch <= 0x007A)
+      ){
+        return true;
+    }
+    return false;
+}
+
+static int32_t 
+_internal_toASCII(const char16_t* src, int32_t srcLength,
+                  char16_t* dest, int32_t destCapacity,
+                  int32_t options,
+                  UStringPrepProfile* nameprep,
+                  UParseError* parseError,
+                  UErrorCode* status)
+{
+
+    // TODO Revisit buffer handling. The label should not be over 63 ASCII characters. ICU4J may need to be updated too.
+    char16_t b1Stack[MAX_LABEL_BUFFER_SIZE], b2Stack[MAX_LABEL_BUFFER_SIZE];
+    //initialize pointers to stack buffers
+    char16_t  *b1 = b1Stack, *b2 = b2Stack;
+    int32_t b1Len=0, b2Len, 
+            b1Capacity = MAX_LABEL_BUFFER_SIZE, 
+            b2Capacity = MAX_LABEL_BUFFER_SIZE ,
+            reqLength=0;
+
+    int32_t namePrepOptions = ((options & UIDNA_ALLOW_UNASSIGNED) != 0) ? USPREP_ALLOW_UNASSIGNED: 0;
+    UBool* caseFlags = nullptr;
+    
+    // the source contains all ascii codepoints
+    UBool srcIsASCII  = true;
+    // assume the source contains all LDH codepoints
+    UBool srcIsLDH = true; 
+
+    int32_t j=0;
+
+    //get the options
+    UBool useSTD3ASCIIRules = static_cast<UBool>((options & UIDNA_USE_STD3_RULES) != 0);
+
+    int32_t failPos = -1;
+    
+    if(srcLength == -1){
+        srcLength = u_strlen(src);
+    }
+    
+    if(srcLength > b1Capacity){
+        b1 = static_cast<char16_t*>(uprv_malloc(srcLength * U_SIZEOF_UCHAR));
+        if(b1==nullptr){
+            *status = U_MEMORY_ALLOCATION_ERROR;
+            goto CLEANUP;
+        }
+        b1Capacity = srcLength;
+    }
+
+    // step 1 
+    for( j=0;j<srcLength;j++){
+        if(src[j] > 0x7F){
+            srcIsASCII = false;
+        }
+        b1[b1Len++] = src[j];
+    }
+    
+    // step 2 is performed only if the source contains non ASCII
+    if(srcIsASCII == false){
+        
+        // step 2    
+        b1Len = usprep_prepare(nameprep, src, srcLength, b1, b1Capacity, namePrepOptions, parseError, status);
+
+        if(*status == U_BUFFER_OVERFLOW_ERROR){
+            // redo processing of string
+            // we do not have enough room so grow the buffer
+            if(b1 != b1Stack){
+                uprv_free(b1);
+            }
+            b1 = static_cast<char16_t*>(uprv_malloc(b1Len * U_SIZEOF_UCHAR));
+            if(b1==nullptr){
+                *status = U_MEMORY_ALLOCATION_ERROR;
+                goto CLEANUP;
+            }
+
+            *status = U_ZERO_ERROR; // reset error
+            
+            b1Len = usprep_prepare(nameprep, src, srcLength, b1, b1Len, namePrepOptions, parseError, status);
+        }
+    }
+    // error bail out
+    if(U_FAILURE(*status)){
+        goto CLEANUP;
+    }
+    if(b1Len == 0){
+        *status = U_IDNA_ZERO_LENGTH_LABEL_ERROR;
+        goto CLEANUP;
+    }
+
+    // for step 3 & 4
+    srcIsASCII = true;
+    for( j=0;j<b1Len;j++){
+        // check if output of usprep_prepare is all ASCII 
+        if(b1[j] > 0x7F){
+            srcIsASCII = false;
+        }else if(isLDHChar(b1[j])==false){  // if the char is in ASCII range verify that it is an LDH character
+            srcIsLDH = false;
+            failPos = j;
+        }
+    }
+    if(useSTD3ASCIIRules){
+        // verify 3a and 3b
+        // 3(a) Verify the absence of non-LDH ASCII code points; that is, the
+        //  absence of 0..2C, 2E..2F, 3A..40, 5B..60, and 7B..7F.
+        // 3(b) Verify the absence of leading and trailing hyphen-minus; that
+        //  is, the absence of U+002D at the beginning and end of the
+        //  sequence.
+        if( srcIsLDH == false /* source at this point should not contain anyLDH characters */
+            || b1[0] ==  HYPHEN || b1[b1Len-1] == HYPHEN){
+            *status = U_IDNA_STD3_ASCII_RULES_ERROR;
+
+            /* populate the parseError struct */
+            if(srcIsLDH==false){
+                // failPos is always set the index of failure
+                uprv_syntaxError(b1,failPos, b1Len,parseError);
+            }else if(b1[0] == HYPHEN){
+                // fail position is 0 
+                uprv_syntaxError(b1,0,b1Len,parseError);
+            }else{
+                // the last index in the source is always length-1
+                uprv_syntaxError(b1, (b1Len>0) ? b1Len-1 : b1Len, b1Len,parseError);
+            }
+
+            goto CLEANUP;
+        }
+    }
+    // Step 4: if the source is ASCII then proceed to step 8
+    if(srcIsASCII){
+        if(b1Len <= destCapacity){
+            u_memmove(dest, b1, b1Len);
+            reqLength = b1Len;
+        }else{
+            reqLength = b1Len;
+            goto CLEANUP;
+        }
+    }else{
+        // step 5 : verify the sequence does not begin with ACE prefix
+        if(!startsWithPrefix(b1,b1Len)){
+
+            //step 6: encode the sequence with punycode
+
+            // do not preserve the case flags for now!
+            // TODO: Preserve the case while implementing the RFE
+            // caseFlags = (UBool*) uprv_malloc(b1Len * sizeof(UBool));
+            // uprv_memset(caseFlags,true,b1Len);
+
+            b2Len = u_strToPunycode(b1,b1Len,b2,b2Capacity,caseFlags, status);
+
+            if(*status == U_BUFFER_OVERFLOW_ERROR){
+                // redo processing of string
+                /* we do not have enough room so grow the buffer*/
+                b2 = static_cast<char16_t*>(uprv_malloc(b2Len * U_SIZEOF_UCHAR));
+                if(b2 == nullptr){
+                    *status = U_MEMORY_ALLOCATION_ERROR;
+                    goto CLEANUP;
+                }
+
+                *status = U_ZERO_ERROR; // reset error
+                
+                b2Len = u_strToPunycode(b1,b1Len,b2,b2Len,caseFlags, status);
+            }
+            //error bail out
+            if(U_FAILURE(*status)){
+                goto CLEANUP;
+            }
+            // TODO : Reconsider while implementing the case preserve RFE
+            // convert all codepoints to lower case ASCII
+            // toASCIILower(b2,b2Len);
+            reqLength = b2Len+ACE_PREFIX_LENGTH;
+
+            if(reqLength > destCapacity){
+                *status = U_BUFFER_OVERFLOW_ERROR;
+                goto CLEANUP;
+            }
+            //Step 7: prepend the ACE prefix
+            u_memcpy(dest, ACE_PREFIX, ACE_PREFIX_LENGTH);
+            //Step 6: copy the contents in b2 into dest
+            u_memcpy(dest+ACE_PREFIX_LENGTH, b2, b2Len);
+
+        }else{
+            *status = U_IDNA_ACE_PREFIX_ERROR; 
+            //position of failure is 0
+            uprv_syntaxError(b1,0,b1Len,parseError);
+            goto CLEANUP;
+        }
+    }
+    // step 8: verify the length of label
+    if(reqLength > MAX_LABEL_LENGTH){
+        *status = U_IDNA_LABEL_TOO_LONG_ERROR;
+    }
+
+CLEANUP:
+    if(b1 != b1Stack){
+        uprv_free(b1);
+    }
+    if(b2 != b2Stack){
+        uprv_free(b2);
+    }
+    uprv_free(caseFlags);
+    
+    return u_terminateUChars(dest, destCapacity, reqLength, status);
+}
+
+static int32_t
+_internal_toUnicode(const char16_t* src, int32_t srcLength,
+                    char16_t* dest, int32_t destCapacity,
+                    int32_t options,
+                    UStringPrepProfile* nameprep,
+                    UParseError* parseError,
+                    UErrorCode* status)
+{
+
+    //get the options
+    //UBool useSTD3ASCIIRules = (UBool)((options & UIDNA_USE_STD3_RULES) != 0);
+    int32_t namePrepOptions = ((options & UIDNA_ALLOW_UNASSIGNED) != 0) ? USPREP_ALLOW_UNASSIGNED: 0; 
+
+    // TODO Revisit buffer handling. The label should not be over 63 ASCII characters. ICU4J may need to be updated too.
+    char16_t b1Stack[MAX_LABEL_BUFFER_SIZE], b2Stack[MAX_LABEL_BUFFER_SIZE], b3Stack[MAX_LABEL_BUFFER_SIZE];
+
+    //initialize pointers to stack buffers
+    char16_t  *b1 = b1Stack, *b2 = b2Stack, *b1Prime=nullptr, *b3=b3Stack;
+    int32_t b1Len = 0, b2Len, b1PrimeLen, b3Len,
+            b1Capacity = MAX_LABEL_BUFFER_SIZE, 
+            b2Capacity = MAX_LABEL_BUFFER_SIZE,
+            b3Capacity = MAX_LABEL_BUFFER_SIZE,
+            reqLength=0;
+
+    UBool* caseFlags = nullptr;
+
+    UBool srcIsASCII = true;
+    /*UBool srcIsLDH = true;
+    int32_t failPos =0;*/
+
+    // step 1: find out if all the codepoints in src are ASCII  
+    if(srcLength==-1){
+        srcLength = 0;
+        for(;src[srcLength]!=0;){
+            if(src[srcLength]> 0x7f){
+                srcIsASCII = false;
+            }/*else if(isLDHChar(src[srcLength])==false){
+                // here we do not assemble surrogates
+                // since we know that LDH code points
+                // are in the ASCII range only
+                srcIsLDH = false;
+                failPos = srcLength;
+            }*/
+            srcLength++;
+        }
+    }else if(srcLength > 0){
+        for(int32_t j=0; j<srcLength; j++){
+            if(src[j]> 0x7f){
+                srcIsASCII = false;
+                break;
+            }/*else if(isLDHChar(src[j])==false){
+                // here we do not assemble surrogates
+                // since we know that LDH code points
+                // are in the ASCII range only
+                srcIsLDH = false;
+                failPos = j;
+            }*/
+        }
+    }else{
+        return 0;
+    }
+    
+    if(srcIsASCII == false){
+        // step 2: process the string
+        b1Len = usprep_prepare(nameprep, src, srcLength, b1, b1Capacity, namePrepOptions, parseError, status);
+        if(*status == U_BUFFER_OVERFLOW_ERROR){
+            // redo processing of string
+            /* we do not have enough room so grow the buffer*/
+            b1 = static_cast<char16_t*>(uprv_malloc(b1Len * U_SIZEOF_UCHAR));
+            if(b1==nullptr){
+                *status = U_MEMORY_ALLOCATION_ERROR;
+                goto CLEANUP;
+            }
+
+            *status = U_ZERO_ERROR; // reset error
+            
+            b1Len = usprep_prepare(nameprep, src, srcLength, b1, b1Len, namePrepOptions, parseError, status);
+        }
+        //bail out on error
+        if(U_FAILURE(*status)){
+            goto CLEANUP;
+        }
+    }else{
+
+        //just point src to b1
+        b1 = const_cast<char16_t*>(src);
+        b1Len = srcLength;
+    }
+
+    // The RFC states that 
+    // <quote>
+    // ToUnicode never fails. If any step fails, then the original input
+    // is returned immediately in that step.
+    // </quote>
+
+    //step 3: verify ACE Prefix
+    if(startsWithPrefix(b1,b1Len)){
+
+        //step 4: Remove the ACE Prefix
+        b1Prime = b1 + ACE_PREFIX_LENGTH;
+        b1PrimeLen  = b1Len - ACE_PREFIX_LENGTH;
+
+        //step 5: Decode using punycode
+        b2Len = u_strFromPunycode(b1Prime, b1PrimeLen, b2, b2Capacity, caseFlags,status);
+
+        if(*status == U_BUFFER_OVERFLOW_ERROR){
+            // redo processing of string
+            /* we do not have enough room so grow the buffer*/
+            b2 = static_cast<char16_t*>(uprv_malloc(b2Len * U_SIZEOF_UCHAR));
+            if(b2==nullptr){
+                *status = U_MEMORY_ALLOCATION_ERROR;
+                goto CLEANUP;
+            }
+
+            *status = U_ZERO_ERROR; // reset error
+
+            b2Len =  u_strFromPunycode(b1Prime, b1PrimeLen, b2, b2Len, caseFlags, status);
+        }
+
+
+        //step 6:Apply toASCII
+        b3Len = uidna_toASCII(b2, b2Len, b3, b3Capacity, options, parseError, status);
+
+        if(*status == U_BUFFER_OVERFLOW_ERROR){
+            // redo processing of string
+            /* we do not have enough room so grow the buffer*/
+            b3 = static_cast<char16_t*>(uprv_malloc(b3Len * U_SIZEOF_UCHAR));
+            if(b3==nullptr){
+                *status = U_MEMORY_ALLOCATION_ERROR;
+                goto CLEANUP;
+            }
+
+            *status = U_ZERO_ERROR; // reset error
+
+            b3Len =  uidna_toASCII(b2,b2Len,b3,b3Len,options,parseError, status);
+
+        }
+        //bail out on error
+        if(U_FAILURE(*status)){
+            goto CLEANUP;
+        }
+
+        //step 7: verify
+        if(compareCaseInsensitiveASCII(b1, b1Len, b3, b3Len) !=0){
+            // Cause the original to be returned.
+            *status = U_IDNA_VERIFICATION_ERROR;
+            goto CLEANUP;
+        }
+
+        //step 8: return output of step 5
+        reqLength = b2Len;
+        if(b2Len <= destCapacity) {
+            u_memmove(dest, b2, b2Len);
+        }
+    }
+    else{
+        // See the start of this if statement for why this is commented out.
+        // verify that STD3 ASCII rules are satisfied
+        /*if(useSTD3ASCIIRules == true){
+            if( srcIsLDH == false // source contains some non-LDH characters
+                || src[0] ==  HYPHEN || src[srcLength-1] == HYPHEN){
+                *status = U_IDNA_STD3_ASCII_RULES_ERROR;
+
+                // populate the parseError struct
+                if(srcIsLDH==false){
+                    // failPos is always set the index of failure
+                    uprv_syntaxError(src,failPos, srcLength,parseError);
+                }else if(src[0] == HYPHEN){
+                    // fail position is 0 
+                    uprv_syntaxError(src,0,srcLength,parseError);
+                }else{
+                    // the last index in the source is always length-1
+                    uprv_syntaxError(src, (srcLength>0) ? srcLength-1 : srcLength, srcLength,parseError);
+                }
+
+                goto CLEANUP;
+            }
+        }*/
+        // just return the source
+        //copy the source to destination
+        if(srcLength <= destCapacity){
+            u_memmove(dest, src, srcLength);
+        }
+        reqLength = srcLength;
+    }
+
+
+CLEANUP:
+
+    if(b1 != b1Stack && b1!=src){
+        uprv_free(b1);
+    }
+    if(b2 != b2Stack){
+        uprv_free(b2);
+    }
+    if(b3 != b3Stack){
+        uprv_free(b3);
+    }
+    uprv_free(caseFlags);
+
+    // The RFC states that 
+    // <quote>
+    // ToUnicode never fails. If any step fails, then the original input
+    // is returned immediately in that step.
+    // </quote>
+    // So if any step fails lets copy source to destination
+    if(U_FAILURE(*status)){
+        //copy the source to destination
+        if(dest && srcLength <= destCapacity){
+            // srcLength should have already been set earlier.
+            U_ASSERT(srcLength >= 0);
+            u_memmove(dest, src, srcLength);
+        }
+        reqLength = srcLength;
+        *status = U_ZERO_ERROR;
+    }
+
+    return u_terminateUChars(dest, destCapacity, reqLength, status);
+}
+
+U_CAPI int32_t U_EXPORT2
+uidna_toASCII(const char16_t* src, int32_t srcLength,
+              char16_t* dest, int32_t destCapacity,
+              int32_t options,
+              UParseError* parseError,
+              UErrorCode* status){
+    
+    if(status == nullptr || U_FAILURE(*status)){
+        return 0;
+    }
+    if((src==nullptr) || (srcLength < -1) || (destCapacity<0) || (!dest && destCapacity > 0)){
+        *status = U_ILLEGAL_ARGUMENT_ERROR;
+        return 0;
+    }
+
+    UStringPrepProfile* nameprep = usprep_openByType(USPREP_RFC3491_NAMEPREP, status);
+    
+    if(U_FAILURE(*status)){
+        return -1;
+    }
+    
+    int32_t retLen = _internal_toASCII(src, srcLength, dest, destCapacity, options, nameprep, parseError, status);
+    
+    /* close the profile*/
+    usprep_close(nameprep);
+    
+    return retLen;
+}
+
+U_CAPI int32_t U_EXPORT2
+uidna_toUnicode(const char16_t* src, int32_t srcLength,
+                char16_t* dest, int32_t destCapacity,
+                int32_t options,
+                UParseError* parseError,
+                UErrorCode* status){
+
+    if(status == nullptr || U_FAILURE(*status)){
+        return 0;
+    }
+    if( (src==nullptr) || (srcLength < -1) || (destCapacity<0) || (!dest && destCapacity > 0)){
+        *status = U_ILLEGAL_ARGUMENT_ERROR;
+        return 0;
+    }  
+
+    UStringPrepProfile* nameprep = usprep_openByType(USPREP_RFC3491_NAMEPREP, status);
+    
+    if(U_FAILURE(*status)){
+        return -1;
+    }
+    
+    int32_t retLen = _internal_toUnicode(src, srcLength, dest, destCapacity, options, nameprep, parseError, status);
+
+    usprep_close(nameprep);
+    
+    return retLen;
+}
+
+
+U_CAPI int32_t U_EXPORT2
+uidna_IDNToASCII(  const char16_t *src, int32_t srcLength,
+                   char16_t* dest, int32_t destCapacity,
+                   int32_t options,
+                   UParseError *parseError,
+                   UErrorCode *status){
+
+    if(status == nullptr || U_FAILURE(*status)){
+        return 0;
+    }
+    if((src==nullptr) || (srcLength < -1) || (destCapacity<0) || (!dest && destCapacity > 0)){
+        *status = U_ILLEGAL_ARGUMENT_ERROR;
+        return 0;
+    }
+
+    int32_t reqLength = 0;
+
+    UStringPrepProfile* nameprep = usprep_openByType(USPREP_RFC3491_NAMEPREP, status);
+    
+    if(U_FAILURE(*status)){
+        return 0;
+    }
+
+    //initialize pointers 
+    char16_t* delimiter = const_cast<char16_t*>(src);
+    char16_t* labelStart = const_cast<char16_t*>(src);
+    char16_t* currentDest = dest;
+    int32_t remainingLen = srcLength;
+    int32_t remainingDestCapacity = destCapacity;
+    int32_t labelLen = 0, labelReqLength = 0;
+    UBool done = false;
+
+
+    for(;;){
+
+        labelLen = getNextSeparator(labelStart,remainingLen, &delimiter,&done);
+        labelReqLength = 0;
+        if(!(labelLen==0 && done)){// make sure this is not a root label separator.
+        
+            labelReqLength = _internal_toASCII( labelStart, labelLen, 
+                                                currentDest, remainingDestCapacity, 
+                                                options, nameprep, 
+                                                parseError, status);
+    
+            if(*status == U_BUFFER_OVERFLOW_ERROR){
+                
+                *status = U_ZERO_ERROR; // reset error
+                remainingDestCapacity = 0;
+            }
+        }
+
+    
+        if(U_FAILURE(*status)){
+            break;
+        }
+        
+        reqLength +=labelReqLength;
+        // adjust the destination pointer
+        if(labelReqLength < remainingDestCapacity){
+            currentDest = currentDest + labelReqLength;
+            remainingDestCapacity -= labelReqLength;
+        }else{
+            // should never occur
+            remainingDestCapacity = 0;
+        }
+
+        if(done){
+            break;
+        }
+
+        // add the label separator
+        if(remainingDestCapacity > 0){
+            *currentDest++ = FULL_STOP;
+            remainingDestCapacity--;
+        }
+        reqLength++;
+
+        labelStart = delimiter;
+        if(remainingLen >0 ){
+            remainingLen = (int32_t)(srcLength - (delimiter - src));
+        }
+
+    }
+
+    if(reqLength > MAX_DOMAIN_NAME_LENGTH){
+        *status = U_IDNA_DOMAIN_NAME_TOO_LONG_ERROR;
+    }
+
+    usprep_close(nameprep);
+    
+    return u_terminateUChars(dest, destCapacity, reqLength, status);
+}
+
+U_CAPI int32_t U_EXPORT2
+uidna_IDNToUnicode(  const char16_t* src, int32_t srcLength,
+                     char16_t* dest, int32_t destCapacity,
+                     int32_t options,
+                     UParseError* parseError,
+                     UErrorCode* status){
+    
+    if(status == nullptr || U_FAILURE(*status)){
+        return 0;
+    }
+    if((src==nullptr) || (srcLength < -1) || (destCapacity<0) || (!dest && destCapacity > 0)){
+        *status = U_ILLEGAL_ARGUMENT_ERROR;
+        return 0;
+    }
+
+    int32_t reqLength = 0;
+
+    UStringPrepProfile* nameprep = usprep_openByType(USPREP_RFC3491_NAMEPREP, status);
+    
+    if(U_FAILURE(*status)){
+        return 0;
+    }
+
+    //initialize pointers
+    char16_t* delimiter = const_cast<char16_t*>(src);
+    char16_t* labelStart = const_cast<char16_t*>(src);
+    char16_t* currentDest = dest;
+    int32_t remainingLen = srcLength;
+    int32_t remainingDestCapacity = destCapacity;
+    int32_t labelLen = 0, labelReqLength = 0;
+    UBool done = false;
+
+    for(;;){
+
+        labelLen = getNextSeparator(labelStart,remainingLen, &delimiter,&done);
+        
+        // The RFC states that 
+        // <quote>
+        // ToUnicode never fails. If any step fails, then the original input
+        // is returned immediately in that step.
+        // </quote>
+        // _internal_toUnicode will copy the label.
+        /*if(labelLen==0 && done==false){ 
+            *status = U_IDNA_ZERO_LENGTH_LABEL_ERROR;
+            break;
+        }*/
+        
+        labelReqLength = _internal_toUnicode(labelStart, labelLen, 
+                                             currentDest, remainingDestCapacity, 
+                                             options, nameprep, 
+                                             parseError, status);
+
+        if(*status == U_BUFFER_OVERFLOW_ERROR){
+            *status = U_ZERO_ERROR; // reset error
+            remainingDestCapacity = 0;
+        }
+
+        if(U_FAILURE(*status)){
+            break;
+        }
+        
+        reqLength +=labelReqLength;
+        // adjust the destination pointer
+        if(labelReqLength < remainingDestCapacity){
+            currentDest = currentDest + labelReqLength;
+            remainingDestCapacity -= labelReqLength;
+        }else{
+            // should never occur
+            remainingDestCapacity = 0;
+        }
+
+        if(done){
+            break;
+        }
+
+        // add the label separator
+        // Unlike the ToASCII operation we don't normalize the label separators
+        if(remainingDestCapacity > 0){
+            *currentDest++ = *(labelStart + labelLen);
+            remainingDestCapacity--;
+        }
+        reqLength++;
+
+        labelStart = delimiter;
+        if(remainingLen >0 ){
+            remainingLen = (int32_t)(srcLength - (delimiter - src));
+        }
+
+    }
+
+    if(reqLength > MAX_DOMAIN_NAME_LENGTH){
+        *status = U_IDNA_DOMAIN_NAME_TOO_LONG_ERROR;
+    }
+
+    usprep_close(nameprep);
+    
+    return u_terminateUChars(dest, destCapacity, reqLength, status);
+}
+
+U_CAPI int32_t U_EXPORT2
+uidna_compare(  const char16_t *s1, int32_t length1,
+                const char16_t *s2, int32_t length2,
+                int32_t options,
+                UErrorCode* status){
+
+    if(status == nullptr || U_FAILURE(*status)){
+        return -1;
+    }
+
+    char16_t b1Stack[MAX_IDN_BUFFER_SIZE], b2Stack[MAX_IDN_BUFFER_SIZE];
+    char16_t *b1 = b1Stack, *b2 = b2Stack;
+    int32_t b1Len, b2Len, b1Capacity = MAX_IDN_BUFFER_SIZE, b2Capacity = MAX_IDN_BUFFER_SIZE;
+    int32_t result=-1;
+    
+    UParseError parseError;
+
+    b1Len = uidna_IDNToASCII(s1, length1, b1, b1Capacity, options, &parseError, status);
+    if(*status == U_BUFFER_OVERFLOW_ERROR){
+        // redo processing of string
+        b1 = (char16_t*) uprv_malloc(b1Len * U_SIZEOF_UCHAR);
+        if(b1==nullptr){
+            *status = U_MEMORY_ALLOCATION_ERROR;
+            goto CLEANUP;
+        }
+
+        *status = U_ZERO_ERROR; // reset error
+        
+        b1Len = uidna_IDNToASCII(s1,length1,b1,b1Len, options, &parseError, status);
+        
+    }
+
+    b2Len = uidna_IDNToASCII(s2,length2, b2,b2Capacity, options, &parseError, status);
+    if(*status == U_BUFFER_OVERFLOW_ERROR){
+        // redo processing of string
+        b2 = (char16_t*) uprv_malloc(b2Len * U_SIZEOF_UCHAR);
+        if(b2==nullptr){
+            *status = U_MEMORY_ALLOCATION_ERROR;
+            goto CLEANUP;
+        }
+
+        *status = U_ZERO_ERROR; // reset error
+        
+        b2Len = uidna_IDNToASCII(s2, length2, b2, b2Len, options, &parseError, status);
+        
+    }
+    // when toASCII is applied all label separators are replaced with FULL_STOP
+    result = compareCaseInsensitiveASCII(b1,b1Len,b2,b2Len);
+
+CLEANUP:
+    if(b1 != b1Stack){
+        uprv_free(b1);
+    }
+
+    if(b2 != b2Stack){
+        uprv_free(b2);
+    }
+
+    return result;
+}
+
+#endif /* #if !UCONFIG_NO_IDNA */