Check in the pristine copy of ICU 4.6...

icu46/source/common/uts46.cpp

+/*
+*******************************************************************************
+*   Copyright (C) 2010, International Business Machines
+*   Corporation and others.  All Rights Reserved.
+*******************************************************************************
+*   file name:  uts46.cpp
+*   encoding:   US-ASCII
+*   tab size:   8 (not used)
+*   indentation:4
+*
+*   created on: 2010mar09
+*   created by: Markus W. Scherer
+*/
+
+#include "unicode/utypes.h"
+
+#if !UCONFIG_NO_IDNA
+
+#include "unicode/idna.h"
+#include "unicode/normalizer2.h"
+#include "unicode/ustring.h"
+#include "cmemory.h"
+#include "cstring.h"
+#include "punycode.h"
+#include "ustr_imp.h"
+
+#define LENGTHOF(array) (int32_t)(sizeof(array)/sizeof((array)[0]))
+
+// Note about tests for UIDNA_ERROR_DOMAIN_NAME_TOO_LONG:
+//
+// The domain name length limit is 255 octets in an internal DNS representation
+// where the last ("root") label is the empty label
+// represented by length byte 0 alone.
+// In a conventional string, this translates to 253 characters, or 254
+// if there is a trailing dot for the root label.
+
+U_NAMESPACE_BEGIN
+
+// Severe errors which usually result in a U+FFFD replacement character in the result string.
+const uint32_t severeErrors=
+    UIDNA_ERROR_LEADING_COMBINING_MARK|
+    UIDNA_ERROR_DISALLOWED|
+    UIDNA_ERROR_PUNYCODE|
+    UIDNA_ERROR_LABEL_HAS_DOT|
+    UIDNA_ERROR_INVALID_ACE_LABEL;
+
+static inline UBool
+isASCIIString(const UnicodeString &dest) {
+    const UChar *s=dest.getBuffer();
+    const UChar *limit=s+dest.length();
+    while(s<limit) {
+        if(*s++>0x7f) {
+            return FALSE;
+        }
+    }
+    return TRUE;
+}
+
+static UBool
+isASCIIOkBiDi(const UChar *s, int32_t length);
+
+static UBool
+isASCIIOkBiDi(const char *s, int32_t length);
+
+// IDNA class default implementations -------------------------------------- ***
+
+void
+IDNA::labelToASCII_UTF8(const StringPiece &label, ByteSink &dest,
+                        IDNAInfo &info, UErrorCode &errorCode) const {
+    if(U_SUCCESS(errorCode)) {
+        UnicodeString destString;
+        labelToASCII(UnicodeString::fromUTF8(label), destString,
+                     info, errorCode).toUTF8(dest);
+    }
+}
+
+void
+IDNA::labelToUnicodeUTF8(const StringPiece &label, ByteSink &dest,
+                         IDNAInfo &info, UErrorCode &errorCode) const {
+    if(U_SUCCESS(errorCode)) {
+        UnicodeString destString;
+        labelToUnicode(UnicodeString::fromUTF8(label), destString,
+                       info, errorCode).toUTF8(dest);
+    }
+}
+
+void
+IDNA::nameToASCII_UTF8(const StringPiece &name, ByteSink &dest,
+                       IDNAInfo &info, UErrorCode &errorCode) const {
+    if(U_SUCCESS(errorCode)) {
+        UnicodeString destString;
+        nameToASCII(UnicodeString::fromUTF8(name), destString,
+                    info, errorCode).toUTF8(dest);
+    }
+}
+
+void
+IDNA::nameToUnicodeUTF8(const StringPiece &name, ByteSink &dest,
+                        IDNAInfo &info, UErrorCode &errorCode) const {
+    if(U_SUCCESS(errorCode)) {
+        UnicodeString destString;
+        nameToUnicode(UnicodeString::fromUTF8(name), destString,
+                      info, errorCode).toUTF8(dest);
+    }
+}
+
+UOBJECT_DEFINE_NO_RTTI_IMPLEMENTATION(IDNA)
+
+// UTS46 class declaration ------------------------------------------------- ***
+
+class UTS46 : public IDNA {
+public:
+    UTS46(uint32_t options, UErrorCode &errorCode);
+    virtual ~UTS46();
+
+    virtual UnicodeString &
+    labelToASCII(const UnicodeString &label, UnicodeString &dest,
+                 IDNAInfo &info, UErrorCode &errorCode) const;
+
+    virtual UnicodeString &
+    labelToUnicode(const UnicodeString &label, UnicodeString &dest,
+                   IDNAInfo &info, UErrorCode &errorCode) const;
+
+    virtual UnicodeString &
+    nameToASCII(const UnicodeString &name, UnicodeString &dest,
+                IDNAInfo &info, UErrorCode &errorCode) const;
+
+    virtual UnicodeString &
+    nameToUnicode(const UnicodeString &name, UnicodeString &dest,
+                  IDNAInfo &info, UErrorCode &errorCode) const;
+
+    virtual void
+    labelToASCII_UTF8(const StringPiece &label, ByteSink &dest,
+                      IDNAInfo &info, UErrorCode &errorCode) const;
+
+    virtual void
+    labelToUnicodeUTF8(const StringPiece &label, ByteSink &dest,
+                       IDNAInfo &info, UErrorCode &errorCode) const;
+
+    virtual void
+    nameToASCII_UTF8(const StringPiece &name, ByteSink &dest,
+                     IDNAInfo &info, UErrorCode &errorCode) const;
+
+    virtual void
+    nameToUnicodeUTF8(const StringPiece &name, ByteSink &dest,
+                      IDNAInfo &info, UErrorCode &errorCode) const;
+
+private:
+    UnicodeString &
+    process(const UnicodeString &src,
+            UBool isLabel, UBool toASCII,
+            UnicodeString &dest,
+            IDNAInfo &info, UErrorCode &errorCode) const;
+
+    void
+    processUTF8(const StringPiece &src,
+                UBool isLabel, UBool toASCII,
+                ByteSink &dest,
+                IDNAInfo &info, UErrorCode &errorCode) const;
+
+    UnicodeString &
+    processUnicode(const UnicodeString &src,
+                   int32_t labelStart, int32_t mappingStart,
+                   UBool isLabel, UBool toASCII,
+                   UnicodeString &dest,
+                   IDNAInfo &info, UErrorCode &errorCode) const;
+
+    // returns the new dest.length()
+    int32_t
+    mapDevChars(UnicodeString &dest, int32_t labelStart, int32_t mappingStart,
+                UErrorCode &errorCode) const;
+
+    // returns the new label length
+    int32_t
+    processLabel(UnicodeString &dest,
+                 int32_t labelStart, int32_t labelLength,
+                 UBool toASCII,
+                 IDNAInfo &info, UErrorCode &errorCode) const;
+    int32_t
+    markBadACELabel(UnicodeString &dest,
+                    int32_t labelStart, int32_t labelLength,
+                    UBool toASCII, IDNAInfo &info) const;
+
+    void
+    checkLabelBiDi(const UChar *label, int32_t labelLength, IDNAInfo &info) const;
+
+    UBool
+    isLabelOkContextJ(const UChar *label, int32_t labelLength) const;
+
+    const Normalizer2 &uts46Norm2;  // uts46.nrm
+    uint32_t options;
+};
+
+IDNA *
+IDNA::createUTS46Instance(uint32_t options, UErrorCode &errorCode) {
+    if(U_SUCCESS(errorCode)) {
+        IDNA *idna=new UTS46(options, errorCode);
+        if(idna==NULL) {
+            errorCode=U_MEMORY_ALLOCATION_ERROR;
+        } else if(U_FAILURE(errorCode)) {
+            delete idna;
+            idna=NULL;
+        }
+        return idna;
+    } else {
+        return NULL;
+    }
+}
+
+// UTS46 implementation ---------------------------------------------------- ***
+
+UTS46::UTS46(uint32_t opt, UErrorCode &errorCode)
+        : uts46Norm2(*Normalizer2::getInstance(NULL, "uts46", UNORM2_COMPOSE, errorCode)),
+          options(opt) {}
+
+UTS46::~UTS46() {}
+
+UnicodeString &
+UTS46::labelToASCII(const UnicodeString &label, UnicodeString &dest,
+                    IDNAInfo &info, UErrorCode &errorCode) const {
+    return process(label, TRUE, TRUE, dest, info, errorCode);
+}
+
+UnicodeString &
+UTS46::labelToUnicode(const UnicodeString &label, UnicodeString &dest,
+                      IDNAInfo &info, UErrorCode &errorCode) const {
+    return process(label, TRUE, FALSE, dest, info, errorCode);
+}
+
+UnicodeString &
+UTS46::nameToASCII(const UnicodeString &name, UnicodeString &dest,
+                   IDNAInfo &info, UErrorCode &errorCode) const {
+    process(name, FALSE, TRUE, dest, info, errorCode);
+    if( dest.length()>=254 && (info.errors&UIDNA_ERROR_DOMAIN_NAME_TOO_LONG)==0 &&
+        isASCIIString(dest) &&
+        (dest.length()>254 || dest[253]!=0x2e)
+    ) {
+        info.errors|=UIDNA_ERROR_DOMAIN_NAME_TOO_LONG;
+    }
+    return dest;
+}
+
+UnicodeString &
+UTS46::nameToUnicode(const UnicodeString &name, UnicodeString &dest,
+                     IDNAInfo &info, UErrorCode &errorCode) const {
+    return process(name, FALSE, FALSE, dest, info, errorCode);
+}
+
+void
+UTS46::labelToASCII_UTF8(const StringPiece &label, ByteSink &dest,
+                         IDNAInfo &info, UErrorCode &errorCode) const {
+    processUTF8(label, TRUE, TRUE, dest, info, errorCode);
+}
+
+void
+UTS46::labelToUnicodeUTF8(const StringPiece &label, ByteSink &dest,
+                          IDNAInfo &info, UErrorCode &errorCode) const {
+    processUTF8(label, TRUE, FALSE, dest, info, errorCode);
+}
+
+void
+UTS46::nameToASCII_UTF8(const StringPiece &name, ByteSink &dest,
+                        IDNAInfo &info, UErrorCode &errorCode) const {
+    processUTF8(name, FALSE, TRUE, dest, info, errorCode);
+}
+
+void
+UTS46::nameToUnicodeUTF8(const StringPiece &name, ByteSink &dest,
+                         IDNAInfo &info, UErrorCode &errorCode) const {
+    processUTF8(name, FALSE, FALSE, dest, info, errorCode);
+}
+
+// UTS #46 data for ASCII characters.
+// The normalizer (using uts46.nrm) maps uppercase ASCII letters to lowercase
+// and passes through all other ASCII characters.
+// If UIDNA_USE_STD3_RULES is set, then non-LDH characters are disallowed
+// using this data.
+// The ASCII fastpath also uses this data.
+// Values: -1=disallowed  0==valid  1==mapped (lowercase)
+static const int8_t asciiData[128]={
+    -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
+    -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
+    // 002D..002E; valid  #  HYPHEN-MINUS..FULL STOP
+    -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,  0,  0, -1,
+    // 0030..0039; valid  #  DIGIT ZERO..DIGIT NINE
+     0,  0,  0,  0,  0,  0,  0,  0,  0,  0, -1, -1, -1, -1, -1, -1,
+    // 0041..005A; mapped  #  LATIN CAPITAL LETTER A..LATIN CAPITAL LETTER Z
+    -1,  1,  1,  1,  1,  1,  1,  1,  1,  1,  1,  1,  1,  1,  1,  1,
+     1,  1,  1,  1,  1,  1,  1,  1,  1,  1,  1, -1, -1, -1, -1, -1,
+    // 0061..007A; valid  #  LATIN SMALL LETTER A..LATIN SMALL LETTER Z
+    -1,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,
+     0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0, -1, -1, -1, -1, -1
+};
+
+UnicodeString &
+UTS46::process(const UnicodeString &src,
+               UBool isLabel, UBool toASCII,
+               UnicodeString &dest,
+               IDNAInfo &info, UErrorCode &errorCode) const {
+    // uts46Norm2.normalize() would do all of this error checking and setup,
+    // but with the ASCII fastpath we do not always call it, and do not
+    // call it first.
+    if(U_FAILURE(errorCode)) {
+        dest.setToBogus();
+        return dest;
+    }
+    const UChar *srcArray=src.getBuffer();
+    if(&dest==&src || srcArray==NULL) {
+        errorCode=U_ILLEGAL_ARGUMENT_ERROR;
+        dest.setToBogus();
+        return dest;
+    }
+    // Arguments are fine, reset output values.
+    dest.remove();
+    info.reset();
+    int32_t srcLength=src.length();
+    if(srcLength==0) {
+        if(toASCII) {
+            info.errors|=UIDNA_ERROR_EMPTY_LABEL;
+        }
+        return dest;
+    }
+    UChar *destArray=dest.getBuffer(srcLength);
+    if(destArray==NULL) {
+        errorCode=U_MEMORY_ALLOCATION_ERROR;
+        return dest;
+    }
+    // ASCII fastpath
+    UBool disallowNonLDHDot=(options&UIDNA_USE_STD3_RULES)!=0;
+    int32_t labelStart=0;
+    int32_t i;
+    for(i=0;; ++i) {
+        if(i==srcLength) {
+            if(toASCII) {
+                if((i-labelStart)>63) {
+                    info.labelErrors|=UIDNA_ERROR_LABEL_TOO_LONG;
+                }
+                // There is a trailing dot if labelStart==i.
+                if(!isLabel && i>=254 && (i>254 || labelStart<i)) {
+                    info.errors|=UIDNA_ERROR_DOMAIN_NAME_TOO_LONG;
+                }
+            }
+            info.errors|=info.labelErrors;
+            dest.releaseBuffer(i);
+            return dest;
+        }
+        UChar c=srcArray[i];
+        if(c>0x7f) {
+            break;
+        }
+        int cData=asciiData[c];
+        if(cData>0) {
+            destArray[i]=c+0x20;  // Lowercase an uppercase ASCII letter.
+        } else if(cData<0 && disallowNonLDHDot) {
+            break;  // Replacing with U+FFFD can be complicated for toASCII.
+        } else {
+            destArray[i]=c;
+            if(c==0x2d) {  // hyphen
+                if(i==(labelStart+3) && srcArray[i-1]==0x2d) {
+                    // "??--..." is Punycode or forbidden.
+                    ++i;  // '-' was copied to dest already
+                    break;
+                }
+                if(i==labelStart) {
+                    // label starts with "-"
+                    info.labelErrors|=UIDNA_ERROR_LEADING_HYPHEN;
+                }
+                if((i+1)==srcLength || srcArray[i+1]==0x2e) {
+                    // label ends with "-"
+                    info.labelErrors|=UIDNA_ERROR_TRAILING_HYPHEN;
+                }
+            } else if(c==0x2e) {  // dot
+                if(isLabel) {
+                    // Replacing with U+FFFD can be complicated for toASCII.
+                    ++i;  // '.' was copied to dest already
+                    break;
+                }
+                if(toASCII) {
+                    // Permit an empty label at the end but not elsewhere.
+                    if(i==labelStart && i<(srcLength-1)) {
+                        info.labelErrors|=UIDNA_ERROR_EMPTY_LABEL;
+                    } else if((i-labelStart)>63) {
+                        info.labelErrors|=UIDNA_ERROR_LABEL_TOO_LONG;
+                    }
+                }
+                info.errors|=info.labelErrors;
+                info.labelErrors=0;
+                labelStart=i+1;
+            }
+        }
+    }
+    info.errors|=info.labelErrors;
+    dest.releaseBuffer(i);
+    processUnicode(src, labelStart, i, isLabel, toASCII, dest, info, errorCode);
+    if( info.isBiDi && U_SUCCESS(errorCode) && (info.errors&severeErrors)==0 &&
+        (!info.isOkBiDi || (labelStart>0 && !isASCIIOkBiDi(dest.getBuffer(), labelStart)))
+    ) {
+        info.errors|=UIDNA_ERROR_BIDI;
+    }
+    return dest;
+}
+
+void
+UTS46::processUTF8(const StringPiece &src,
+                   UBool isLabel, UBool toASCII,
+                   ByteSink &dest,
+                   IDNAInfo &info, UErrorCode &errorCode) const {
+    if(U_FAILURE(errorCode)) {
+        return;
+    }
+    const char *srcArray=src.data();
+    int32_t srcLength=src.length();
+    if(srcArray==NULL && srcLength!=0) {
+        errorCode=U_ILLEGAL_ARGUMENT_ERROR;
+        return;
+    }
+    // Arguments are fine, reset output values.
+    info.reset();
+    if(srcLength==0) {
+        if(toASCII) {
+            info.errors|=UIDNA_ERROR_EMPTY_LABEL;
+        }
+        dest.Flush();
+        return;
+    }
+    UnicodeString destString;
+    int32_t labelStart=0;
+    if(srcLength<=256) {  // length of stackArray[]
+        // ASCII fastpath
+        char stackArray[256];
+        int32_t destCapacity;
+        char *destArray=dest.GetAppendBuffer(srcLength, srcLength+20,
+                                             stackArray, LENGTHOF(stackArray), &destCapacity);
+        UBool disallowNonLDHDot=(options&UIDNA_USE_STD3_RULES)!=0;
+        int32_t i;
+        for(i=0;; ++i) {
+            if(i==srcLength) {
+                if(toASCII) {
+                    if((i-labelStart)>63) {
+                        info.labelErrors|=UIDNA_ERROR_LABEL_TOO_LONG;
+                    }
+                    // There is a trailing dot if labelStart==i.
+                    if(!isLabel && i>=254 && (i>254 || labelStart<i)) {
+                        info.errors|=UIDNA_ERROR_DOMAIN_NAME_TOO_LONG;
+                    }
+                }
+                info.errors|=info.labelErrors;
+                dest.Append(destArray, i);
+                dest.Flush();
+                return;
+            }
+            char c=srcArray[i];
+            if((int8_t)c<0) {  // (uint8_t)c>0x7f
+                break;
+            }
+            int cData=asciiData[(int)c];  // Cast: gcc warns about indexing with a char.
+            if(cData>0) {
+                destArray[i]=c+0x20;  // Lowercase an uppercase ASCII letter.
+            } else if(cData<0 && disallowNonLDHDot) {
+                break;  // Replacing with U+FFFD can be complicated for toASCII.
+            } else {
+                destArray[i]=c;
+                if(c==0x2d) {  // hyphen
+                    if(i==(labelStart+3) && srcArray[i-1]==0x2d) {
+                        // "??--..." is Punycode or forbidden.
+                        break;
+                    }
+                    if(i==labelStart) {
+                        // label starts with "-"
+                        info.labelErrors|=UIDNA_ERROR_LEADING_HYPHEN;
+                    }
+                    if((i+1)==srcLength || srcArray[i+1]==0x2e) {
+                        // label ends with "-"
+                        info.labelErrors|=UIDNA_ERROR_TRAILING_HYPHEN;
+                    }
+                } else if(c==0x2e) {  // dot
+                    if(isLabel) {
+                        break;  // Replacing with U+FFFD can be complicated for toASCII.
+                    }
+                    if(toASCII) {
+                        // Permit an empty label at the end but not elsewhere.
+                        if(i==labelStart && i<(srcLength-1)) {
+                            info.labelErrors|=UIDNA_ERROR_EMPTY_LABEL;
+                        } else if((i-labelStart)>63) {
+                            info.labelErrors|=UIDNA_ERROR_LABEL_TOO_LONG;
+                        }
+                    }
+                    info.errors|=info.labelErrors;
+                    info.labelErrors=0;
+                    labelStart=i+1;
+                }
+            }
+        }
+        info.errors|=info.labelErrors;
+        // Convert the processed ASCII prefix of the current label to UTF-16.
+        int32_t mappingStart=i-labelStart;
+        destString=UnicodeString::fromUTF8(StringPiece(destArray+labelStart, mappingStart));
+        // Output the previous ASCII labels and process the rest of src in UTF-16.
+        dest.Append(destArray, labelStart);
+        processUnicode(UnicodeString::fromUTF8(StringPiece(src, labelStart)), 0, mappingStart,
+                       isLabel, toASCII,
+                       destString, info, errorCode);
+    } else {
+        // src is too long for the ASCII fastpath implementation.
+        processUnicode(UnicodeString::fromUTF8(src), 0, 0,
+                       isLabel, toASCII,
+                       destString, info, errorCode);
+    }
+    destString.toUTF8(dest);  // calls dest.Flush()
+    if(toASCII && !isLabel) {
+        // length==labelStart==254 means that there is a trailing dot (ok) and
+        // destString is empty (do not index at 253-labelStart).
+        int32_t length=labelStart+destString.length();
+        if( length>=254 && isASCIIString(destString) &&
+            (length>254 ||
+             (labelStart<254 && destString[253-labelStart]!=0x2e))
+        ) {
+            info.errors|=UIDNA_ERROR_DOMAIN_NAME_TOO_LONG;
+        }
+    }
+    if( info.isBiDi && U_SUCCESS(errorCode) && (info.errors&severeErrors)==0 &&
+        (!info.isOkBiDi || (labelStart>0 && !isASCIIOkBiDi(srcArray, labelStart)))
+    ) {
+        info.errors|=UIDNA_ERROR_BIDI;
+    }
+}
+
+UnicodeString &
+UTS46::processUnicode(const UnicodeString &src,
+                      int32_t labelStart, int32_t mappingStart,
+                      UBool isLabel, UBool toASCII,
+                      UnicodeString &dest,
+                      IDNAInfo &info, UErrorCode &errorCode) const {
+    if(mappingStart==0) {
+        uts46Norm2.normalize(src, dest, errorCode);
+    } else {
+        uts46Norm2.normalizeSecondAndAppend(dest, src.tempSubString(mappingStart), errorCode);
+    }
+    if(U_FAILURE(errorCode)) {
+        return dest;
+    }
+    UBool doMapDevChars=
+        toASCII ? (options&UIDNA_NONTRANSITIONAL_TO_ASCII)==0 :
+                  (options&UIDNA_NONTRANSITIONAL_TO_UNICODE)==0;
+    const UChar *destArray=dest.getBuffer();
+    int32_t destLength=dest.length();
+    int32_t labelLimit=labelStart;
+    while(labelLimit<destLength) {
+        UChar c=destArray[labelLimit];
+        if(c==0x2e && !isLabel) {
+            int32_t labelLength=labelLimit-labelStart;
+            int32_t newLength=processLabel(dest, labelStart, labelLength,
+                                            toASCII, info, errorCode);
+            info.errors|=info.labelErrors;
+            info.labelErrors=0;
+            if(U_FAILURE(errorCode)) {
+                return dest;
+            }
+            destArray=dest.getBuffer();
+            destLength+=newLength-labelLength;
+            labelLimit=labelStart+=newLength+1;
+        } else if(0xdf<=c && c<=0x200d && (c==0xdf || c==0x3c2 || c>=0x200c)) {
+            info.isTransDiff=TRUE;
+            if(doMapDevChars) {
+                destLength=mapDevChars(dest, labelStart, labelLimit, errorCode);
+                if(U_FAILURE(errorCode)) {
+                    return dest;
+                }
+                destArray=dest.getBuffer();
+                // Do not increment labelLimit in case c was removed.
+                // All deviation characters have been mapped, no need to check for them again.
+                doMapDevChars=FALSE;
+            } else {
+                ++labelLimit;
+            }
+        } else {
+            ++labelLimit;
+        }
+    }
+    // Permit an empty label at the end (0<labelStart==labelLimit==destLength is ok)
+    // but not an empty label elsewhere nor a completely empty domain name.
+    // processLabel() sets UIDNA_ERROR_EMPTY_LABEL when labelLength==0.
+    if(0==labelStart || labelStart<labelLimit) {
+        processLabel(dest, labelStart, labelLimit-labelStart,
+                      toASCII, info, errorCode);
+        info.errors|=info.labelErrors;
+    }
+    return dest;
+}
+
+int32_t
+UTS46::mapDevChars(UnicodeString &dest, int32_t labelStart, int32_t mappingStart,
+                   UErrorCode &errorCode) const {
+    int32_t length=dest.length();
+    UChar *s=dest.getBuffer(dest[mappingStart]==0xdf ? length+1 : length);
+    if(s==NULL) {
+        errorCode=U_MEMORY_ALLOCATION_ERROR;
+        return length;
+    }
+    int32_t capacity=dest.getCapacity();
+    UBool didMapDevChars=FALSE;
+    int32_t readIndex=mappingStart, writeIndex=mappingStart;
+    do {
+        UChar c=s[readIndex++];
+        switch(c) {
+        case 0xdf:
+            // Map sharp s to ss.
+            didMapDevChars=TRUE;
+            s[writeIndex++]=0x73;  // Replace sharp s with first s.
+            // Insert second s and account for possible buffer reallocation.
+            if(writeIndex==readIndex) {
+                if(length==capacity) {
+                    dest.releaseBuffer(length);
+                    s=dest.getBuffer(length+1);
+                    if(s==NULL) {
+                        errorCode=U_MEMORY_ALLOCATION_ERROR;
+                        return length;
+                    }
+                    capacity=dest.getCapacity();
+                }
+                u_memmove(s+writeIndex+1, s+writeIndex, length-writeIndex);
+                ++readIndex;
+            }
+            s[writeIndex++]=0x73;
+            ++length;
+            break;
+        case 0x3c2:  // Map final sigma to nonfinal sigma.
+            didMapDevChars=TRUE;
+            s[writeIndex++]=0x3c3;
+            break;
+        case 0x200c:  // Ignore/remove ZWNJ.
+        case 0x200d:  // Ignore/remove ZWJ.
+            didMapDevChars=TRUE;
+            --length;
+            break;
+        default:
+            // Only really necessary if writeIndex was different from readIndex.
+            s[writeIndex++]=c;
+            break;
+        }
+    } while(writeIndex<length);
+    dest.releaseBuffer(length);
+    if(didMapDevChars) {
+        // Mapping deviation characters might have resulted in an un-NFC string.
+        // We could use either the NFC or the UTS #46 normalizer.
+        // By using the UTS #46 normalizer again, we avoid having to load a second .nrm data file.
+        UnicodeString normalized;
+        uts46Norm2.normalize(dest.tempSubString(labelStart), normalized, errorCode);
+        if(U_SUCCESS(errorCode)) {
+            dest.replace(labelStart, 0x7fffffff, normalized);
+            return dest.length();
+        }
+    }
+    return length;
+}
+
+// Some non-ASCII characters are equivalent to sequences with
+// non-LDH ASCII characters. To find them:
+// grep disallowed_STD3_valid IdnaMappingTable.txt (or uts46.txt)
+static inline UBool
+isNonASCIIDisallowedSTD3Valid(UChar32 c) {
+    return c==0x2260 || c==0x226E || c==0x226F;
+}
+
+// Replace the label in dest with the label string, if the label was modified.
+// If &label==&dest then the label was modified in-place and labelLength
+// is the new label length, different from label.length().
+// If &label!=&dest then labelLength==label.length().
+// Returns labelLength (= the new label length).
+static int32_t
+replaceLabel(UnicodeString &dest, int32_t destLabelStart, int32_t destLabelLength,
+             const UnicodeString &label, int32_t labelLength) {
+    if(&label!=&dest) {
+        dest.replace(destLabelStart, destLabelLength, label);
+    }
+    return labelLength;
+}
+
+int32_t
+UTS46::processLabel(UnicodeString &dest,
+                    int32_t labelStart, int32_t labelLength,
+                    UBool toASCII,
+                    IDNAInfo &info, UErrorCode &errorCode) const {
+    UnicodeString fromPunycode;
+    UnicodeString *labelString;
+    const UChar *label=dest.getBuffer()+labelStart;
+    int32_t destLabelStart=labelStart;
+    int32_t destLabelLength=labelLength;
+    UBool wasPunycode;
+    if(labelLength>=4 && label[0]==0x78 && label[1]==0x6e && label[2]==0x2d && label[3]==0x2d) {
+        // Label starts with "xn--", try to un-Punycode it.
+        wasPunycode=TRUE;
+        UChar *unicodeBuffer=fromPunycode.getBuffer(-1);  // capacity==-1: most labels should fit
+        if(unicodeBuffer==NULL) {
+            // Should never occur if we used capacity==-1 which uses the internal buffer.
+            errorCode=U_MEMORY_ALLOCATION_ERROR;
+            return labelLength;
+        }
+        UErrorCode punycodeErrorCode=U_ZERO_ERROR;
+        int32_t unicodeLength=u_strFromPunycode(label+4, labelLength-4,
+                                                unicodeBuffer, fromPunycode.getCapacity(),
+                                                NULL, &punycodeErrorCode);
+        if(punycodeErrorCode==U_BUFFER_OVERFLOW_ERROR) {
+            fromPunycode.releaseBuffer(0);
+            unicodeBuffer=fromPunycode.getBuffer(unicodeLength);
+            if(unicodeBuffer==NULL) {
+                errorCode=U_MEMORY_ALLOCATION_ERROR;
+                return labelLength;
+            }
+            punycodeErrorCode=U_ZERO_ERROR;
+            unicodeLength=u_strFromPunycode(label+4, labelLength-4,
+                                            unicodeBuffer, fromPunycode.getCapacity(),
+                                            NULL, &punycodeErrorCode);
+        }
+        fromPunycode.releaseBuffer(unicodeLength);
+        if(U_FAILURE(punycodeErrorCode)) {
+            info.labelErrors|=UIDNA_ERROR_PUNYCODE;
+            return markBadACELabel(dest, labelStart, labelLength, toASCII, info);
+        }
+        // Check for NFC, and for characters that are not
+        // valid or deviation characters according to the normalizer.
+        // If there is something wrong, then the string will change.
+        // Note that the normalizer passes through non-LDH ASCII and deviation characters.
+        // Deviation characters are ok in Punycode even in transitional processing.
+        // In the code further below, if we find non-LDH ASCII and we have UIDNA_USE_STD3_RULES
+        // then we will set UIDNA_ERROR_INVALID_ACE_LABEL there too.
+        UBool isValid=uts46Norm2.isNormalized(fromPunycode, errorCode);
+        if(U_FAILURE(errorCode)) {
+            return labelLength;
+        }
+        if(!isValid) {
+            info.labelErrors|=UIDNA_ERROR_INVALID_ACE_LABEL;
+            return markBadACELabel(dest, labelStart, labelLength, toASCII, info);
+        }
+        labelString=&fromPunycode;
+        label=fromPunycode.getBuffer();
+        labelStart=0;
+        labelLength=fromPunycode.length();
+    } else {
+        wasPunycode=FALSE;
+        labelString=&dest;
+    }
+    // Validity check
+    if(labelLength==0) {
+        if(toASCII) {
+            info.labelErrors|=UIDNA_ERROR_EMPTY_LABEL;
+        }
+        return replaceLabel(dest, destLabelStart, destLabelLength, *labelString, labelLength);
+    }
+    // labelLength>0
+    if(labelLength>=4 && label[2]==0x2d && label[3]==0x2d) {
+        // label starts with "??--"
+        info.labelErrors|=UIDNA_ERROR_HYPHEN_3_4;
+    }
+    if(label[0]==0x2d) {
+        // label starts with "-"
+        info.labelErrors|=UIDNA_ERROR_LEADING_HYPHEN;
+    }
+    if(label[labelLength-1]==0x2d) {
+        // label ends with "-"
+        info.labelErrors|=UIDNA_ERROR_TRAILING_HYPHEN;
+    }
+    // If the label was not a Punycode label, then it was the result of
+    // mapping, normalization and label segmentation.
+    // If the label was in Punycode, then we mapped it again above
+    // and checked its validity.
+    // Now we handle the STD3 restriction to LDH characters (if set)
+    // and we look for U+FFFD which indicates disallowed characters
+    // in a non-Punycode label or U+FFFD itself in a Punycode label.
+    // We also check for dots which can come from the input to a single-label function.
+    // Ok to cast away const because we own the UnicodeString.
+    UChar *s=(UChar *)label;
+    const UChar *limit=label+labelLength;
+    UChar oredChars=0;
+    // If we enforce STD3 rules, then ASCII characters other than LDH and dot are disallowed.
+    UBool disallowNonLDHDot=(options&UIDNA_USE_STD3_RULES)!=0;
+    do {
+        UChar c=*s;
+        if(c<=0x7f) {
+            if(c==0x2e) {
+                info.labelErrors|=UIDNA_ERROR_LABEL_HAS_DOT;
+                *s=0xfffd;
+            } else if(disallowNonLDHDot && asciiData[c]<0) {
+                info.labelErrors|=UIDNA_ERROR_DISALLOWED;
+                *s=0xfffd;
+            }
+        } else {
+            oredChars|=c;
+            if(disallowNonLDHDot && isNonASCIIDisallowedSTD3Valid(c)) {
+                info.labelErrors|=UIDNA_ERROR_DISALLOWED;
+                *s=0xfffd;
+            } else if(c==0xfffd) {
+                info.labelErrors|=UIDNA_ERROR_DISALLOWED;
+            }
+        }
+        ++s;
+    } while(s<limit);
+    // Check for a leading combining mark after other validity checks
+    // so that we don't report UIDNA_ERROR_DISALLOWED for the U+FFFD from here.
+    UChar32 c;
+    int32_t cpLength=0;
+    // "Unsafe" is ok because unpaired surrogates were mapped to U+FFFD.
+    U16_NEXT_UNSAFE(label, cpLength, c);
+    if((U_GET_GC_MASK(c)&U_GC_M_MASK)!=0) {
+        info.labelErrors|=UIDNA_ERROR_LEADING_COMBINING_MARK;
+        labelString->replace(labelStart, cpLength, (UChar)0xfffd);
+        label=labelString->getBuffer()+labelStart;
+        labelLength+=1-cpLength;
+        if(labelString==&dest) {
+            destLabelLength=labelLength;
+        }
+    }
+    if((info.labelErrors&severeErrors)==0) {
+        // Do contextual checks only if we do not have U+FFFD from a severe error
+        // because U+FFFD can make these checks fail.
+        if((options&UIDNA_CHECK_BIDI)!=0 && (!info.isBiDi || info.isOkBiDi)) {
+            checkLabelBiDi(label, labelLength, info);
+        }
+        if( (options&UIDNA_CHECK_CONTEXTJ)!=0 && (oredChars&0x200c)==0x200c &&
+            !isLabelOkContextJ(label, labelLength)
+        ) {
+            info.labelErrors|=UIDNA_ERROR_CONTEXTJ;
+        }
+        if(toASCII) {
+            if(wasPunycode) {
+                // Leave a Punycode label unchanged if it has no severe errors.
+                if(destLabelLength>63) {
+                    info.labelErrors|=UIDNA_ERROR_LABEL_TOO_LONG;
+                }
+                return destLabelLength;
+            } else if(oredChars>=0x80) {
+                // Contains non-ASCII characters.
+                UnicodeString punycode;
+                UChar *buffer=punycode.getBuffer(63);  // 63==maximum DNS label length
+                if(buffer==NULL) {
+                    errorCode=U_MEMORY_ALLOCATION_ERROR;
+                    return destLabelLength;
+                }
+                buffer[0]=0x78;  // Write "xn--".
+                buffer[1]=0x6e;
+                buffer[2]=0x2d;
+                buffer[3]=0x2d;
+                int32_t punycodeLength=u_strToPunycode(label, labelLength,
+                                                      buffer+4, punycode.getCapacity()-4,
+                                                      NULL, &errorCode);
+                if(errorCode==U_BUFFER_OVERFLOW_ERROR) {
+                    errorCode=U_ZERO_ERROR;
+                    punycode.releaseBuffer(4);
+                    buffer=punycode.getBuffer(4+punycodeLength);
+                    if(buffer==NULL) {
+                        errorCode=U_MEMORY_ALLOCATION_ERROR;
+                        return destLabelLength;
+                    }
+                    punycodeLength=u_strToPunycode(label, labelLength,
+                                                  buffer+4, punycode.getCapacity()-4,
+                                                  NULL, &errorCode);
+                }
+                punycodeLength+=4;
+                punycode.releaseBuffer(punycodeLength);
+                if(U_FAILURE(errorCode)) {
+                    return destLabelLength;
+                }
+                if(punycodeLength>63) {
+                    info.labelErrors|=UIDNA_ERROR_LABEL_TOO_LONG;
+                }
+                return replaceLabel(dest, destLabelStart, destLabelLength,
+                                    punycode, punycodeLength);
+            } else {
+                // all-ASCII label
+                if(labelLength>63) {
+                    info.labelErrors|=UIDNA_ERROR_LABEL_TOO_LONG;
+                }
+            }
+        }
+    } else {
+        // If a Punycode label has severe errors,
+        // then leave it but make sure it does not look valid.
+        if(wasPunycode) {
+            info.labelErrors|=UIDNA_ERROR_INVALID_ACE_LABEL;
+            return markBadACELabel(dest, destLabelStart, destLabelLength, toASCII, info);
+        }
+    }
+    return replaceLabel(dest, destLabelStart, destLabelLength, *labelString, labelLength);
+}
+
+// Make sure an ACE label does not look valid.
+// Append U+FFFD if the label has only LDH characters.
+// If UIDNA_USE_STD3_RULES, also replace disallowed ASCII characters with U+FFFD.
+int32_t
+UTS46::markBadACELabel(UnicodeString &dest,
+                       int32_t labelStart, int32_t labelLength,
+                       UBool toASCII, IDNAInfo &info) const {
+    UBool disallowNonLDHDot=(options&UIDNA_USE_STD3_RULES)!=0;
+    UBool isASCII=TRUE;
+    UBool onlyLDH=TRUE;
+    const UChar *label=dest.getBuffer()+labelStart;
+    // Ok to cast away const because we own the UnicodeString.
+    UChar *s=(UChar *)label+4;  // After the initial "xn--".
+    const UChar *limit=label+labelLength;
+    do {
+        UChar c=*s;
+        if(c<=0x7f) {
+            if(c==0x2e) {
+                info.labelErrors|=UIDNA_ERROR_LABEL_HAS_DOT;
+                *s=0xfffd;
+                isASCII=onlyLDH=FALSE;
+            } else if(asciiData[c]<0) {
+                onlyLDH=FALSE;
+                if(disallowNonLDHDot) {
+                    *s=0xfffd;
+                    isASCII=FALSE;
+                }
+            }
+        } else {
+            isASCII=onlyLDH=FALSE;
+        }
+    } while(++s<limit);
+    if(onlyLDH) {
+        dest.insert(labelStart+labelLength, (UChar)0xfffd);
+        ++labelLength;
+    } else {
+        if(toASCII && isASCII && labelLength>63) {
+            info.labelErrors|=UIDNA_ERROR_LABEL_TOO_LONG;
+        }
+    }
+    return labelLength;
+}
+
+const uint32_t L_MASK=U_MASK(U_LEFT_TO_RIGHT);
+const uint32_t R_AL_MASK=U_MASK(U_RIGHT_TO_LEFT)|U_MASK(U_RIGHT_TO_LEFT_ARABIC);
+const uint32_t L_R_AL_MASK=L_MASK|R_AL_MASK;
+
+const uint32_t R_AL_AN_MASK=R_AL_MASK|U_MASK(U_ARABIC_NUMBER);
+
+const uint32_t EN_AN_MASK=U_MASK(U_EUROPEAN_NUMBER)|U_MASK(U_ARABIC_NUMBER);
+const uint32_t R_AL_EN_AN_MASK=R_AL_MASK|EN_AN_MASK;
+const uint32_t L_EN_MASK=L_MASK|U_MASK(U_EUROPEAN_NUMBER);
+
+const uint32_t ES_CS_ET_ON_BN_NSM_MASK=
+    U_MASK(U_EUROPEAN_NUMBER_SEPARATOR)|
+    U_MASK(U_COMMON_NUMBER_SEPARATOR)|
+    U_MASK(U_EUROPEAN_NUMBER_TERMINATOR)|
+    U_MASK(U_OTHER_NEUTRAL)|
+    U_MASK(U_BOUNDARY_NEUTRAL)|
+    U_MASK(U_DIR_NON_SPACING_MARK);
+const uint32_t L_EN_ES_CS_ET_ON_BN_NSM_MASK=L_EN_MASK|ES_CS_ET_ON_BN_NSM_MASK;
+const uint32_t R_AL_AN_EN_ES_CS_ET_ON_BN_NSM_MASK=R_AL_MASK|EN_AN_MASK|ES_CS_ET_ON_BN_NSM_MASK;
+
+// We scan the whole label and check both for whether it contains RTL characters
+// and whether it passes the BiDi Rule.
+// In a BiDi domain name, all labels must pass the BiDi Rule, but we might find
+// that a domain name is a BiDi domain name (has an RTL label) only after
+// processing several earlier labels.
+void
+UTS46::checkLabelBiDi(const UChar *label, int32_t labelLength, IDNAInfo &info) const {
+    // IDNA2008 BiDi rule
+    // Get the directionality of the first character.
+    UChar32 c;
+    int32_t i=0;
+    U16_NEXT_UNSAFE(label, i, c);
+    uint32_t firstMask=U_MASK(u_charDirection(c));
+    // 1. The first character must be a character with BIDI property L, R
+    // or AL.  If it has the R or AL property, it is an RTL label; if it
+    // has the L property, it is an LTR label.
+    if((firstMask&~L_R_AL_MASK)!=0) {
+        info.isOkBiDi=FALSE;
+    }
+    // Get the directionality of the last non-NSM character.
+    uint32_t lastMask;
+    for(;;) {
+        if(i>=labelLength) {
+            lastMask=firstMask;
+            break;
+        }
+        U16_PREV_UNSAFE(label, labelLength, c);
+        UCharDirection dir=u_charDirection(c);
+        if(dir!=U_DIR_NON_SPACING_MARK) {
+            lastMask=U_MASK(dir);
+            break;
+        }
+    }
+    // 3. In an RTL label, the end of the label must be a character with
+    // BIDI property R, AL, EN or AN, followed by zero or more
+    // characters with BIDI property NSM.
+    // 6. In an LTR label, the end of the label must be a character with
+    // BIDI property L or EN, followed by zero or more characters with
+    // BIDI property NSM.
+    if( (firstMask&L_MASK)!=0 ?
+            (lastMask&~L_EN_MASK)!=0 :
+            (lastMask&~R_AL_EN_AN_MASK)!=0
+    ) {
+        info.isOkBiDi=FALSE;
+    }
+    // Get the directionalities of the intervening characters.
+    uint32_t mask=0;
+    while(i<labelLength) {
+        U16_NEXT_UNSAFE(label, i, c);
+        mask|=U_MASK(u_charDirection(c));
+    }
+    if(firstMask&L_MASK) {
+        // 5. In an LTR label, only characters with the BIDI properties L, EN,
+        // ES, CS, ET, ON, BN and NSM are allowed.
+        if((mask&~L_EN_ES_CS_ET_ON_BN_NSM_MASK)!=0) {
+            info.isOkBiDi=FALSE;
+        }
+    } else {
+        // 2. In an RTL label, only characters with the BIDI properties R, AL,
+        // AN, EN, ES, CS, ET, ON, BN and NSM are allowed.
+        if((mask&~R_AL_AN_EN_ES_CS_ET_ON_BN_NSM_MASK)!=0) {
+            info.isOkBiDi=FALSE;
+        }
+        // 4. In an RTL label, if an EN is present, no AN may be present, and
+        // vice versa.
+        if((mask&EN_AN_MASK)==EN_AN_MASK) {
+            info.isOkBiDi=FALSE;
+        }
+    }
+    // An RTL label is a label that contains at least one character of type
+    // R, AL or AN. [...]
+    // A "BIDI domain name" is a domain name that contains at least one RTL
+    // label. [...]
+    // The following rule, consisting of six conditions, applies to labels
+    // in BIDI domain names.
+    if(((firstMask|mask|lastMask)&R_AL_AN_MASK)!=0) {
+        info.isBiDi=TRUE;
+    }
+}
+
+// Special code for the ASCII prefix of a BiDi domain name.
+// The ASCII prefix is all-LTR.
+
+// IDNA2008 BiDi rule, parts relevant to ASCII labels:
+// 1. The first character must be a character with BIDI property L [...]
+// 5. In an LTR label, only characters with the BIDI properties L, EN,
+// ES, CS, ET, ON, BN and NSM are allowed.
+// 6. In an LTR label, the end of the label must be a character with
+// BIDI property L or EN [...]
+
+// UTF-16 version, called for mapped ASCII prefix.
+// Cannot contain uppercase A-Z.
+// s[length-1] must be the trailing dot.
+static UBool
+isASCIIOkBiDi(const UChar *s, int32_t length) {
+    int32_t labelStart=0;
+    for(int32_t i=0; i<length; ++i) {
+        UChar c=s[i];
+        if(c==0x2e) {  // dot
+            if(i>labelStart) {
+                c=s[i-1];
+                if(!(0x61<=c && c<=0x7a) && !(0x30<=c && c<=0x39)) {
+                    // Last character in the label is not an L or EN.
+                    return FALSE;
+                }
+            }
+            labelStart=i+1;
+        } else if(i==labelStart) {
+            if(!(0x61<=c && c<=0x7a)) {
+                // First character in the label is not an L.
+                return FALSE;
+            }
+        } else {
+            if(c<=0x20 && (c>=0x1c || (9<=c && c<=0xd))) {
+                // Intermediate character in the label is a B, S or WS.
+                return FALSE;
+            }
+        }
+    }
+    return TRUE;
+}
+
+// UTF-8 version, called for source ASCII prefix.
+// Can contain uppercase A-Z.
+// s[length-1] must be the trailing dot.
+static UBool
+isASCIIOkBiDi(const char *s, int32_t length) {
+    int32_t labelStart=0;
+    for(int32_t i=0; i<length; ++i) {
+        char c=s[i];
+        if(c==0x2e) {  // dot
+            if(i>labelStart) {
+                c=s[i-1];
+                if(!(0x61<=c && c<=0x7a) && !(0x41<=c && c<=0x5a) && !(0x30<=c && c<=0x39)) {
+                    // Last character in the label is not an L or EN.
+                    return FALSE;
+                }
+            }
+            labelStart=i+1;
+        } else if(i==labelStart) {
+            if(!(0x61<=c && c<=0x7a) && !(0x41<=c && c<=0x5a)) {
+                // First character in the label is not an L.
+                return FALSE;
+            }
+        } else {
+            if(c<=0x20 && (c>=0x1c || (9<=c && c<=0xd))) {
+                // Intermediate character in the label is a B, S or WS.
+                return FALSE;
+            }
+        }
+    }
+    return TRUE;
+}
+
+UBool
+UTS46::isLabelOkContextJ(const UChar *label, int32_t labelLength) const {
+    // [IDNA2008-Tables]
+    // 200C..200D  ; CONTEXTJ    # ZERO WIDTH NON-JOINER..ZERO WIDTH JOINER
+    for(int32_t i=0; i<labelLength; ++i) {
+        if(label[i]==0x200c) {
+            // Appendix A.1. ZERO WIDTH NON-JOINER
+            // Rule Set:
+            //  False;
+            //  If Canonical_Combining_Class(Before(cp)) .eq.  Virama Then True;
+            //  If RegExpMatch((Joining_Type:{L,D})(Joining_Type:T)*\u200C
+            //     (Joining_Type:T)*(Joining_Type:{R,D})) Then True;
+            if(i==0) {
+                return FALSE;
+            }
+            UChar32 c;
+            int32_t j=i;
+            U16_PREV_UNSAFE(label, j, c);
+            if(u_getCombiningClass(c)==9) {
+                continue;
+            }
+            // check precontext (Joining_Type:{L,D})(Joining_Type:T)*
+            for(;;) {
+                UJoiningType type=(UJoiningType)u_getIntPropertyValue(c, UCHAR_JOINING_TYPE);
+                if(type==U_JT_TRANSPARENT) {
+                    if(j==0) {
+                        return FALSE;
+                    }
+                    U16_PREV_UNSAFE(label, j, c);
+                } else if(type==U_JT_LEFT_JOINING || type==U_JT_DUAL_JOINING) {
+                    break;  // precontext fulfilled
+                } else {
+                    return FALSE;
+                }
+            }
+            // check postcontext (Joining_Type:T)*(Joining_Type:{R,D})
+            for(j=i+1;;) {
+                if(j==labelLength) {
+                    return FALSE;
+                }
+                U16_NEXT_UNSAFE(label, j, c);
+                UJoiningType type=(UJoiningType)u_getIntPropertyValue(c, UCHAR_JOINING_TYPE);
+                if(type==U_JT_TRANSPARENT) {
+                    // just skip this character
+                } else if(type==U_JT_RIGHT_JOINING || type==U_JT_DUAL_JOINING) {
+                    break;  // postcontext fulfilled
+                } else {
+                    return FALSE;
+                }
+            }
+        } else if(label[i]==0x200d) {
+            // Appendix A.2. ZERO WIDTH JOINER (U+200D)
+            // Rule Set:
+            //  False;
+            //  If Canonical_Combining_Class(Before(cp)) .eq.  Virama Then True;
+            if(i==0) {
+                return FALSE;
+            }
+            UChar32 c;
+            int32_t j=i;
+            U16_PREV_UNSAFE(label, j, c);
+            if(u_getCombiningClass(c)!=9) {
+                return FALSE;
+            }
+        }
+    }
+    return TRUE;
+}
+
+U_NAMESPACE_END
+
+// C API ------------------------------------------------------------------- ***
+
+U_NAMESPACE_USE
+
+U_DRAFT UIDNA * U_EXPORT2
+uidna_openUTS46(uint32_t options, UErrorCode *pErrorCode) {
+    return reinterpret_cast<UIDNA *>(IDNA::createUTS46Instance(options, *pErrorCode));
+}
+
+U_DRAFT void U_EXPORT2
+uidna_close(UIDNA *idna) {
+    delete reinterpret_cast<IDNA *>(idna);
+}
+
+static UBool
+checkArgs(const void *label, int32_t length,
+          void *dest, int32_t capacity,
+          UIDNAInfo *pInfo, UErrorCode *pErrorCode) {
+    if(U_FAILURE(*pErrorCode)) {
+        return FALSE;
+    }
+    // sizeof(UIDNAInfo)=16 in the first API version.
+    if(pInfo==NULL || pInfo->size<16) {
+        *pErrorCode=U_ILLEGAL_ARGUMENT_ERROR;
+        return FALSE;
+    }
+    if( (label==NULL ? length!=0 : length<-1) ||
+        (dest==NULL ? capacity!=0 : capacity<0) ||
+        (dest==label && label!=NULL)
+    ) {
+        *pErrorCode=U_ILLEGAL_ARGUMENT_ERROR;
+        return FALSE;
+    }
+    // Set all *pInfo bytes to 0 except for the size field itself.
+    uprv_memset(&pInfo->size+1, 0, pInfo->size-sizeof(pInfo->size));
+    return TRUE;
+}
+
+static void
+idnaInfoToStruct(IDNAInfo &info, UIDNAInfo *pInfo) {
+    pInfo->isTransitionalDifferent=info.isTransitionalDifferent();
+    pInfo->errors=info.getErrors();
+}
+
+U_DRAFT int32_t U_EXPORT2
+uidna_labelToASCII(const UIDNA *idna,
+                   const UChar *label, int32_t length,
+                   UChar *dest, int32_t capacity,
+                   UIDNAInfo *pInfo, UErrorCode *pErrorCode) {
+    if(!checkArgs(label, length, dest, capacity, pInfo, pErrorCode)) {
+        return 0;
+    }
+    UnicodeString src((UBool)(length<0), label, length);
+    UnicodeString destString(dest, 0, capacity);
+    IDNAInfo info;
+    reinterpret_cast<const IDNA *>(idna)->labelToASCII(src, destString, info, *pErrorCode);
+    idnaInfoToStruct(info, pInfo);
+    return destString.extract(dest, capacity, *pErrorCode);
+}
+
+U_DRAFT int32_t U_EXPORT2
+uidna_labelToUnicode(const UIDNA *idna,
+                     const UChar *label, int32_t length,
+                     UChar *dest, int32_t capacity,
+                     UIDNAInfo *pInfo, UErrorCode *pErrorCode) {
+    if(!checkArgs(label, length, dest, capacity, pInfo, pErrorCode)) {
+        return 0;
+    }
+    UnicodeString src((UBool)(length<0), label, length);
+    UnicodeString destString(dest, 0, capacity);
+    IDNAInfo info;
+    reinterpret_cast<const IDNA *>(idna)->labelToUnicode(src, destString, info, *pErrorCode);
+    idnaInfoToStruct(info, pInfo);
+    return destString.extract(dest, capacity, *pErrorCode);
+}
+
+U_DRAFT int32_t U_EXPORT2
+uidna_nameToASCII(const UIDNA *idna,
+                  const UChar *name, int32_t length,
+                  UChar *dest, int32_t capacity,
+                  UIDNAInfo *pInfo, UErrorCode *pErrorCode) {
+    if(!checkArgs(name, length, dest, capacity, pInfo, pErrorCode)) {
+        return 0;
+    }
+    UnicodeString src((UBool)(length<0), name, length);
+    UnicodeString destString(dest, 0, capacity);
+    IDNAInfo info;
+    reinterpret_cast<const IDNA *>(idna)->nameToASCII(src, destString, info, *pErrorCode);
+    idnaInfoToStruct(info, pInfo);
+    return destString.extract(dest, capacity, *pErrorCode);
+}
+
+U_DRAFT int32_t U_EXPORT2
+uidna_nameToUnicode(const UIDNA *idna,
+                    const UChar *name, int32_t length,
+                    UChar *dest, int32_t capacity,
+                    UIDNAInfo *pInfo, UErrorCode *pErrorCode) {
+    if(!checkArgs(name, length, dest, capacity, pInfo, pErrorCode)) {
+        return 0;
+    }
+    UnicodeString src((UBool)(length<0), name, length);
+    UnicodeString destString(dest, 0, capacity);
+    IDNAInfo info;
+    reinterpret_cast<const IDNA *>(idna)->nameToUnicode(src, destString, info, *pErrorCode);
+    idnaInfoToStruct(info, pInfo);
+    return destString.extract(dest, capacity, *pErrorCode);
+}
+
+U_DRAFT int32_t U_EXPORT2
+uidna_labelToASCII_UTF8(const UIDNA *idna,
+                        const char *label, int32_t length,
+                        char *dest, int32_t capacity,
+                        UIDNAInfo *pInfo, UErrorCode *pErrorCode) {
+    if(!checkArgs(label, length, dest, capacity, pInfo, pErrorCode)) {
+        return 0;
+    }
+    StringPiece src(label, length<0 ? uprv_strlen(label) : length);
+    CheckedArrayByteSink sink(dest, capacity);
+    IDNAInfo info;
+    reinterpret_cast<const IDNA *>(idna)->labelToASCII_UTF8(src, sink, info, *pErrorCode);
+    idnaInfoToStruct(info, pInfo);
+    return u_terminateChars(dest, capacity, sink.NumberOfBytesAppended(), pErrorCode);
+}
+
+U_DRAFT int32_t U_EXPORT2
+uidna_labelToUnicodeUTF8(const UIDNA *idna,
+                         const char *label, int32_t length,
+                         char *dest, int32_t capacity,
+                         UIDNAInfo *pInfo, UErrorCode *pErrorCode) {
+    if(!checkArgs(label, length, dest, capacity, pInfo, pErrorCode)) {
+        return 0;
+    }
+    StringPiece src(label, length<0 ? uprv_strlen(label) : length);
+    CheckedArrayByteSink sink(dest, capacity);
+    IDNAInfo info;
+    reinterpret_cast<const IDNA *>(idna)->labelToUnicodeUTF8(src, sink, info, *pErrorCode);
+    idnaInfoToStruct(info, pInfo);
+    return u_terminateChars(dest, capacity, sink.NumberOfBytesAppended(), pErrorCode);
+}
+
+U_DRAFT int32_t U_EXPORT2
+uidna_nameToASCII_UTF8(const UIDNA *idna,
+                       const char *name, int32_t length,
+                       char *dest, int32_t capacity,
+                       UIDNAInfo *pInfo, UErrorCode *pErrorCode) {
+    if(!checkArgs(name, length, dest, capacity, pInfo, pErrorCode)) {
+        return 0;
+    }
+    StringPiece src(name, length<0 ? uprv_strlen(name) : length);
+    CheckedArrayByteSink sink(dest, capacity);
+    IDNAInfo info;
+    reinterpret_cast<const IDNA *>(idna)->nameToASCII_UTF8(src, sink, info, *pErrorCode);
+    idnaInfoToStruct(info, pInfo);
+    return u_terminateChars(dest, capacity, sink.NumberOfBytesAppended(), pErrorCode);
+}
+
+U_DRAFT int32_t U_EXPORT2
+uidna_nameToUnicodeUTF8(const UIDNA *idna,
+                        const char *name, int32_t length,
+                        char *dest, int32_t capacity,
+                        UIDNAInfo *pInfo, UErrorCode *pErrorCode) {
+    if(!checkArgs(name, length, dest, capacity, pInfo, pErrorCode)) {
+        return 0;
+    }
+    StringPiece src(name, length<0 ? uprv_strlen(name) : length);
+    CheckedArrayByteSink sink(dest, capacity);
+    IDNAInfo info;
+    reinterpret_cast<const IDNA *>(idna)->nameToUnicodeUTF8(src, sink, info, *pErrorCode);
+    idnaInfoToStruct(info, pInfo);
+    return u_terminateChars(dest, capacity, sink.NumberOfBytesAppended(), pErrorCode);
+}
+
+#endif  // UCONFIG_NO_IDNA