// © 2016 and later: Unicode, Inc. and others. // License & terms of use: http://www.unicode.org/copyright.html /* ********************************************************************** * Copyright (C) 2002-2016, International Business Machines * Corporation and others. All Rights Reserved. ********************************************************************** * file name: ucnv_u7.c * encoding: UTF-8 * tab size: 8 (not used) * indentation:4 * * created on: 2002jul01 * created by: Markus W. Scherer * * UTF-7 converter implementation. Used to be in ucnv_utf.c. */ #include "unicode/utypes.h" #if !UCONFIG_NO_CONVERSION && !UCONFIG_ONLY_HTML_CONVERSION #include "cmemory.h" #include "unicode/ucnv.h" #include "ucnv_bld.h" #include "ucnv_cnv.h" #include "uassert.h" /* UTF-7 -------------------------------------------------------------------- */ /* * UTF-7 is a stateful encoding of Unicode. * It is defined in RFC 2152. (http://www.ietf.org/rfc/rfc2152.txt) * It was intended for use in Internet email systems, using in its bytewise * encoding only a subset of 7-bit US-ASCII. * UTF-7 is deprecated in favor of UTF-8/16/32 and SCSU, but still * occasionally used. * * For converting Unicode to UTF-7, the RFC allows to encode some US-ASCII * characters directly or in base64. Especially, the characters in set O * as defined in the RFC (see below) may be encoded directly but are not * allowed in, e.g., email headers. * By default, the ICU UTF-7 converter encodes set O directly. * By choosing the option "version=1", set O will be escaped instead. * For example: * utf7Converter=ucnv_open("UTF-7,version=1"); * * For details about email headers see RFC 2047. */ /* * Tests for US-ASCII characters belonging to character classes * defined in UTF-7. * * Set D (directly encoded characters) consists of the following * characters: the upper and lower case letters A through Z * and a through z, the 10 digits 0-9, and the following nine special * characters (note that "+" and "=" are omitted): * '(),-./:? * * Set O (optional direct characters) consists of the following * characters (note that "\" and "~" are omitted): * !"#$%&*;<=>@[]^_`{|} * * According to the rules in RFC 2152, the byte values for the following * US-ASCII characters are not used in UTF-7 and are therefore illegal: * - all C0 control codes except for CR LF TAB * - BACKSLASH * - TILDE * - DEL * - all codes beyond US-ASCII, i.e. all >127 */ #define inSetD … #define inSetO … #define isCRLFTAB … #define isCRLFSPTAB … #define PLUS … #define MINUS … #define BACKSLASH … #define TILDE … /* legal byte values: all US-ASCII graphic characters from space to before tilde, and CR LF TAB */ #define isLegalUTF7 … /* encode directly sets D and O and CR LF SP TAB */ static const UBool encodeDirectlyMaximum[128]={ /* 0 1 2 3 4 5 6 7 8 9 a b c d e f */ 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 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, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 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, 1, 0, 0 }; /* encode directly set D and CR LF SP TAB but not set O */ static const UBool encodeDirectlyRestricted[128]={ /* 0 1 2 3 4 5 6 7 8 9 a b c d e f */ 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 1, 1, 1, 0, 0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 0, 0, 0, 1, 0, 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, 0, 0, 0, 0, 0, 0, 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, 0, 0, 0, 0, 0 }; static const uint8_t toBase64[64]={ /* A-Z */ 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79, 80, 81, 82, 83, 84, 85, 86, 87, 88, 89, 90, /* a-z */ 97, 98, 99, 100, 101, 102, 103, 104, 105, 106, 107, 108, 109, 110, 111, 112, 113, 114, 115, 116, 117, 118, 119, 120, 121, 122, /* 0-9 */ 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, /* +/ */ 43, 47 }; static const int8_t fromBase64[128]={ /* C0 controls, -1 for legal ones (CR LF TAB), -3 for illegal ones */ -3, -3, -3, -3, -3, -3, -3, -3, -3, -1, -1, -3, -3, -1, -3, -3, -3, -3, -3, -3, -3, -3, -3, -3, -3, -3, -3, -3, -3, -3, -3, -3, /* general punctuation with + and / and a special value (-2) for - */ -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, 62, -1, -2, -1, 63, /* digits */ 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, -1, -1, -1, -1, -1, -1, /* A-Z */ -1, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, -1, -3, -1, -1, -1, /* a-z */ -1, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, -1, -1, -1, -3, -3 }; /* * converter status values: * * toUnicodeStatus: * 24 inDirectMode (boolean) * 23..16 base64Counter (-1..7) * 15..0 bits (up to 14 bits incoming base64) * * fromUnicodeStatus: * 31..28 version (0: set O direct 1: set O escaped) * 24 inDirectMode (boolean) * 23..16 base64Counter (0..2) * 7..0 bits (6 bits outgoing base64) * */ U_CDECL_BEGIN static void U_CALLCONV _UTF7Reset(UConverter *cnv, UConverterResetChoice choice) { if(choice<=UCNV_RESET_TO_UNICODE) { /* reset toUnicode */ cnv->toUnicodeStatus=0x1000000; /* inDirectMode=true */ cnv->toULength=0; } if(choice!=UCNV_RESET_TO_UNICODE) { /* reset fromUnicode */ cnv->fromUnicodeStatus=(cnv->fromUnicodeStatus&0xf0000000)|0x1000000; /* keep version, inDirectMode=true */ } } static void U_CALLCONV _UTF7Open(UConverter *cnv, UConverterLoadArgs *pArgs, UErrorCode *pErrorCode) { (void)pArgs; if(UCNV_GET_VERSION(cnv)<=1) { /* TODO(markus): Should just use cnv->options rather than copying the version number. */ cnv->fromUnicodeStatus=UCNV_GET_VERSION(cnv)<<28; _UTF7Reset(cnv, UCNV_RESET_BOTH); } else { *pErrorCode=U_ILLEGAL_ARGUMENT_ERROR; } } static void U_CALLCONV _UTF7ToUnicodeWithOffsets(UConverterToUnicodeArgs *pArgs, UErrorCode *pErrorCode) { UConverter *cnv; const uint8_t *source, *sourceLimit; char16_t *target; const char16_t *targetLimit; int32_t *offsets; uint8_t *bytes; uint8_t byteIndex; int32_t length, targetCapacity; /* UTF-7 state */ uint16_t bits; int8_t base64Counter; UBool inDirectMode; int8_t base64Value; int32_t sourceIndex, nextSourceIndex; uint8_t b; /* set up the local pointers */ cnv=pArgs->converter; source=(const uint8_t *)pArgs->source; sourceLimit=(const uint8_t *)pArgs->sourceLimit; target=pArgs->target; targetLimit=pArgs->targetLimit; offsets=pArgs->offsets; /* get the state machine state */ { uint32_t status=cnv->toUnicodeStatus; inDirectMode=(UBool)((status>>24)&1); base64Counter=(int8_t)(status>>16); bits=(uint16_t)status; } bytes=cnv->toUBytes; byteIndex=cnv->toULength; /* sourceIndex=-1 if the current character began in the previous buffer */ sourceIndex=byteIndex==0 ? 0 : -1; nextSourceIndex=0; if(inDirectMode) { directMode: /* * In Direct Mode, most US-ASCII characters are encoded directly, i.e., * with their US-ASCII byte values. * Backslash and Tilde and most control characters are not allowed in UTF-7. * A plus sign starts Unicode (or "escape") Mode. * * In Direct Mode, only the sourceIndex is used. */ byteIndex=0; length=(int32_t)(sourceLimit-source); targetCapacity=(int32_t)(targetLimit-target); if(length>targetCapacity) { length=targetCapacity; } while(length>0) { b=*source++; if(!isLegalUTF7(b)) { /* illegal */ bytes[0]=b; byteIndex=1; *pErrorCode=U_ILLEGAL_CHAR_FOUND; break; } else if(b!=PLUS) { /* write directly encoded character */ *target++=b; if(offsets!=nullptr) { *offsets++=sourceIndex++; } } else /* PLUS */ { /* switch to Unicode mode */ nextSourceIndex=++sourceIndex; inDirectMode=false; byteIndex=0; bits=0; base64Counter=-1; goto unicodeMode; } --length; } if(source<sourceLimit && target>=targetLimit) { /* target is full */ *pErrorCode=U_BUFFER_OVERFLOW_ERROR; } } else { unicodeMode: /* * In Unicode (or "escape") Mode, UTF-16BE is base64-encoded. * The base64 sequence ends with any character that is not in the base64 alphabet. * A terminating minus sign is consumed. * * In Unicode Mode, the sourceIndex has the index to the start of the current * base64 bytes, while nextSourceIndex is precisely parallel to source, * keeping the index to the following byte. * Note that in 2 out of 3 cases, UChars overlap within a base64 byte. */ while(source<sourceLimit) { if(target<targetLimit) { bytes[byteIndex++]=b=*source++; ++nextSourceIndex; base64Value = -3; /* initialize as illegal */ if(b>=126 || (base64Value=fromBase64[b])==-3 || base64Value==-1) { /* either * base64Value==-1 for any legal character except base64 and minus sign, or * base64Value==-3 for illegal characters: * 1. In either case, leave Unicode mode. * 2.1. If we ended with an incomplete char16_t or none after the +, then * generate an error for the preceding erroneous sequence and deal with * the current (possibly illegal) character next time through. * 2.2. Else the current char comes after a complete char16_t, which was already * pushed to the output buf, so: * 2.2.1. If the current char is legal, just save it for processing next time. * It may be for example, a plus which we need to deal with in direct mode. * 2.2.2. Else if the current char is illegal, we might as well deal with it here. */ inDirectMode=true; if(base64Counter==-1) { /* illegal: + immediately followed by something other than base64 or minus sign */ /* include the plus sign in the reported sequence, but not the subsequent char */ --source; bytes[0]=PLUS; byteIndex=1; *pErrorCode=U_ILLEGAL_CHAR_FOUND; break; } else if(bits!=0) { /* bits are illegally left over, a char16_t is incomplete */ /* don't include current char (legal or illegal) in error seq */ --source; --byteIndex; *pErrorCode=U_ILLEGAL_CHAR_FOUND; break; } else { /* previous char16_t was complete */ if(base64Value==-3) { /* current character is illegal, deal with it here */ *pErrorCode=U_ILLEGAL_CHAR_FOUND; break; } else { /* un-read the current character in case it is a plus sign */ --source; sourceIndex=nextSourceIndex-1; goto directMode; } } } else if(base64Value>=0) { /* collect base64 bytes into UChars */ switch(base64Counter) { case -1: /* -1 is immediately after the + */ case 0: bits=base64Value; base64Counter=1; break; case 1: case 3: case 4: case 6: bits=(uint16_t)((bits<<6)|base64Value); ++base64Counter; break; case 2: *target++=(char16_t)((bits<<4)|(base64Value>>2)); if(offsets!=nullptr) { *offsets++=sourceIndex; sourceIndex=nextSourceIndex-1; } bytes[0]=b; /* keep this byte in case an error occurs */ byteIndex=1; bits=(uint16_t)(base64Value&3); base64Counter=3; break; case 5: *target++=(char16_t)((bits<<2)|(base64Value>>4)); if(offsets!=nullptr) { *offsets++=sourceIndex; sourceIndex=nextSourceIndex-1; } bytes[0]=b; /* keep this byte in case an error occurs */ byteIndex=1; bits=(uint16_t)(base64Value&15); base64Counter=6; break; case 7: *target++=(char16_t)((bits<<6)|base64Value); if(offsets!=nullptr) { *offsets++=sourceIndex; sourceIndex=nextSourceIndex; } byteIndex=0; bits=0; base64Counter=0; break; default: /* will never occur */ break; } } else /*base64Value==-2*/ { /* minus sign terminates the base64 sequence */ inDirectMode=true; if(base64Counter==-1) { /* +- i.e. a minus immediately following a plus */ *target++=PLUS; if(offsets!=nullptr) { *offsets++=sourceIndex-1; } } else { /* absorb the minus and leave the Unicode Mode */ if(bits!=0) { /* bits are illegally left over, a char16_t is incomplete */ *pErrorCode=U_ILLEGAL_CHAR_FOUND; break; } } sourceIndex=nextSourceIndex; goto directMode; } } else { /* target is full */ *pErrorCode=U_BUFFER_OVERFLOW_ERROR; break; } } } if(U_SUCCESS(*pErrorCode) && pArgs->flush && source==sourceLimit && bits==0) { /* * if we are in Unicode mode, then the byteIndex might not be 0, * but that is ok if bits==0 * -> we set byteIndex=0 at the end of the stream to avoid a truncated error * (not true for IMAP-mailbox-name where we must end in direct mode) */ byteIndex=0; } /* set the converter state back into UConverter */ cnv->toUnicodeStatus=((uint32_t)inDirectMode<<24)|((uint32_t)((uint8_t)base64Counter)<<16)|(uint32_t)bits; cnv->toULength=byteIndex; /* write back the updated pointers */ pArgs->source=(const char *)source; pArgs->target=target; pArgs->offsets=offsets; } static void U_CALLCONV _UTF7FromUnicodeWithOffsets(UConverterFromUnicodeArgs *pArgs, UErrorCode *pErrorCode) { UConverter *cnv; const char16_t *source, *sourceLimit; uint8_t *target, *targetLimit; int32_t *offsets; int32_t length, targetCapacity, sourceIndex; char16_t c; /* UTF-7 state */ const UBool *encodeDirectly; uint8_t bits; int8_t base64Counter; UBool inDirectMode; /* set up the local pointers */ cnv=pArgs->converter; /* set up the local pointers */ source=pArgs->source; sourceLimit=pArgs->sourceLimit; target=(uint8_t *)pArgs->target; targetLimit=(uint8_t *)pArgs->targetLimit; offsets=pArgs->offsets; /* get the state machine state */ { uint32_t status=cnv->fromUnicodeStatus; encodeDirectly= status<0x10000000 ? encodeDirectlyMaximum : encodeDirectlyRestricted; inDirectMode=(UBool)((status>>24)&1); base64Counter=(int8_t)(status>>16); bits=(uint8_t)status; U_ASSERT(bits<=UPRV_LENGTHOF(toBase64)); } /* UTF-7 always encodes UTF-16 code units, therefore we need only a simple sourceIndex */ sourceIndex=0; if(inDirectMode) { directMode: length=(int32_t)(sourceLimit-source); targetCapacity=(int32_t)(targetLimit-target); if(length>targetCapacity) { length=targetCapacity; } while(length>0) { c=*source++; /* currently always encode CR LF SP TAB directly */ if(c<=127 && encodeDirectly[c]) { /* encode directly */ *target++=(uint8_t)c; if(offsets!=nullptr) { *offsets++=sourceIndex++; } } else if(c==PLUS) { /* output +- for + */ *target++=PLUS; if(target<targetLimit) { *target++=MINUS; if(offsets!=nullptr) { *offsets++=sourceIndex; *offsets++=sourceIndex++; } /* realign length and targetCapacity */ goto directMode; } else { if(offsets!=nullptr) { *offsets++=sourceIndex++; } cnv->charErrorBuffer[0]=MINUS; cnv->charErrorBufferLength=1; *pErrorCode=U_BUFFER_OVERFLOW_ERROR; break; } } else { /* un-read this character and switch to Unicode Mode */ --source; *target++=PLUS; if(offsets!=nullptr) { *offsets++=sourceIndex; } inDirectMode=false; base64Counter=0; goto unicodeMode; } --length; } if(source<sourceLimit && target>=targetLimit) { /* target is full */ *pErrorCode=U_BUFFER_OVERFLOW_ERROR; } } else { unicodeMode: while(source<sourceLimit) { if(target<targetLimit) { c=*source++; if(c<=127 && encodeDirectly[c]) { /* encode directly */ inDirectMode=true; /* trick: back out this character to make this easier */ --source; /* terminate the base64 sequence */ if(base64Counter!=0) { /* write remaining bits for the previous character */ *target++=toBase64[bits]; if(offsets!=nullptr) { *offsets++=sourceIndex-1; } } if(fromBase64[c]!=-1) { /* need to terminate with a minus */ if(target<targetLimit) { *target++=MINUS; if(offsets!=nullptr) { *offsets++=sourceIndex-1; } } else { cnv->charErrorBuffer[0]=MINUS; cnv->charErrorBufferLength=1; *pErrorCode=U_BUFFER_OVERFLOW_ERROR; break; } } goto directMode; } else { /* * base64 this character: * Output 2 or 3 base64 bytes for the remaining bits of the previous character * and the bits of this character, each implicitly in UTF-16BE. * * Here, bits is an 8-bit variable because only 6 bits need to be kept from one * character to the next. The actual 2 or 4 bits are shifted to the left edge * of the 6-bits field 5..0 to make the termination of the base64 sequence easier. */ switch(base64Counter) { case 0: *target++=toBase64[c>>10]; if(target<targetLimit) { *target++=toBase64[(c>>4)&0x3f]; if(offsets!=nullptr) { *offsets++=sourceIndex; *offsets++=sourceIndex++; } } else { if(offsets!=nullptr) { *offsets++=sourceIndex++; } cnv->charErrorBuffer[0]=toBase64[(c>>4)&0x3f]; cnv->charErrorBufferLength=1; *pErrorCode=U_BUFFER_OVERFLOW_ERROR; } bits=(uint8_t)((c&15)<<2); base64Counter=1; break; case 1: *target++=toBase64[bits|(c>>14)]; if(target<targetLimit) { *target++=toBase64[(c>>8)&0x3f]; if(target<targetLimit) { *target++=toBase64[(c>>2)&0x3f]; if(offsets!=nullptr) { *offsets++=sourceIndex; *offsets++=sourceIndex; *offsets++=sourceIndex++; } } else { if(offsets!=nullptr) { *offsets++=sourceIndex; *offsets++=sourceIndex++; } cnv->charErrorBuffer[0]=toBase64[(c>>2)&0x3f]; cnv->charErrorBufferLength=1; *pErrorCode=U_BUFFER_OVERFLOW_ERROR; } } else { if(offsets!=nullptr) { *offsets++=sourceIndex++; } cnv->charErrorBuffer[0]=toBase64[(c>>8)&0x3f]; cnv->charErrorBuffer[1]=toBase64[(c>>2)&0x3f]; cnv->charErrorBufferLength=2; *pErrorCode=U_BUFFER_OVERFLOW_ERROR; } bits=(uint8_t)((c&3)<<4); base64Counter=2; break; case 2: *target++=toBase64[bits|(c>>12)]; if(target<targetLimit) { *target++=toBase64[(c>>6)&0x3f]; if(target<targetLimit) { *target++=toBase64[c&0x3f]; if(offsets!=nullptr) { *offsets++=sourceIndex; *offsets++=sourceIndex; *offsets++=sourceIndex++; } } else { if(offsets!=nullptr) { *offsets++=sourceIndex; *offsets++=sourceIndex++; } cnv->charErrorBuffer[0]=toBase64[c&0x3f]; cnv->charErrorBufferLength=1; *pErrorCode=U_BUFFER_OVERFLOW_ERROR; } } else { if(offsets!=nullptr) { *offsets++=sourceIndex++; } cnv->charErrorBuffer[0]=toBase64[(c>>6)&0x3f]; cnv->charErrorBuffer[1]=toBase64[c&0x3f]; cnv->charErrorBufferLength=2; *pErrorCode=U_BUFFER_OVERFLOW_ERROR; } bits=0; base64Counter=0; break; default: /* will never occur */ break; } } } else { /* target is full */ *pErrorCode=U_BUFFER_OVERFLOW_ERROR; break; } } } if(pArgs->flush && source>=sourceLimit) { /* flush remaining bits to the target */ if(!inDirectMode) { if (base64Counter!=0) { if(target<targetLimit) { *target++=toBase64[bits]; if(offsets!=nullptr) { *offsets++=sourceIndex-1; } } else { cnv->charErrorBuffer[cnv->charErrorBufferLength++]=toBase64[bits]; *pErrorCode=U_BUFFER_OVERFLOW_ERROR; } } /* Add final MINUS to terminate unicodeMode */ if(target<targetLimit) { *target++=MINUS; if(offsets!=nullptr) { *offsets++=sourceIndex-1; } } else { cnv->charErrorBuffer[cnv->charErrorBufferLength++]=MINUS; *pErrorCode=U_BUFFER_OVERFLOW_ERROR; } } /* reset the state for the next conversion */ cnv->fromUnicodeStatus=(cnv->fromUnicodeStatus&0xf0000000)|0x1000000; /* keep version, inDirectMode=true */ } else { /* set the converter state back into UConverter */ cnv->fromUnicodeStatus= (cnv->fromUnicodeStatus&0xf0000000)| /* keep version*/ ((uint32_t)inDirectMode<<24)|((uint32_t)base64Counter<<16)|(uint32_t)bits; } /* write back the updated pointers */ pArgs->source=source; pArgs->target=(char *)target; pArgs->offsets=offsets; } static const char * U_CALLCONV _UTF7GetName(const UConverter *cnv) { switch(cnv->fromUnicodeStatus>>28) { case 1: return "UTF-7,version=1"; default: return "UTF-7"; } } U_CDECL_END static const UConverterImpl _UTF7Impl={ UCNV_UTF7, nullptr, nullptr, _UTF7Open, nullptr, _UTF7Reset, _UTF7ToUnicodeWithOffsets, _UTF7ToUnicodeWithOffsets, _UTF7FromUnicodeWithOffsets, _UTF7FromUnicodeWithOffsets, nullptr, nullptr, _UTF7GetName, nullptr, /* we don't need writeSub() because we never call a callback at fromUnicode() */ nullptr, ucnv_getCompleteUnicodeSet, nullptr, nullptr }; static const UConverterStaticData _UTF7StaticData={ sizeof(UConverterStaticData), "UTF-7", 0, /* TODO CCSID for UTF-7 */ UCNV_IBM, UCNV_UTF7, 1, 4, { 0x3f, 0, 0, 0 }, 1, /* the subchar is not used */ false, false, 0, 0, { 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0 } /* reserved */ }; const UConverterSharedData _UTF7Data= UCNV_IMMUTABLE_SHARED_DATA_INITIALIZER(&_UTF7StaticData, &_UTF7Impl); /* IMAP mailbox name encoding ----------------------------------------------- */ /* * RFC 2060: INTERNET MESSAGE ACCESS PROTOCOL - VERSION 4rev1 * http://www.ietf.org/rfc/rfc2060.txt * * 5.1.3. Mailbox International Naming Convention * * By convention, international mailbox names are specified using a * modified version of the UTF-7 encoding described in [UTF-7]. The * purpose of these modifications is to correct the following problems * with UTF-7: * * 1) UTF-7 uses the "+" character for shifting; this conflicts with * the common use of "+" in mailbox names, in particular USENET * newsgroup names. * * 2) UTF-7's encoding is BASE64 which uses the "/" character; this * conflicts with the use of "/" as a popular hierarchy delimiter. * * 3) UTF-7 prohibits the unencoded usage of "\"; this conflicts with * the use of "\" as a popular hierarchy delimiter. * * 4) UTF-7 prohibits the unencoded usage of "~"; this conflicts with * the use of "~" in some servers as a home directory indicator. * * 5) UTF-7 permits multiple alternate forms to represent the same * string; in particular, printable US-ASCII characters can be * represented in encoded form. * * In modified UTF-7, printable US-ASCII characters except for "&" * represent themselves; that is, characters with octet values 0x20-0x25 * and 0x27-0x7e. The character "&" (0x26) is represented by the two- * octet sequence "&-". * * All other characters (octet values 0x00-0x1f, 0x7f-0xff, and all * Unicode 16-bit octets) are represented in modified BASE64, with a * further modification from [UTF-7] that "," is used instead of "/". * Modified BASE64 MUST NOT be used to represent any printing US-ASCII * character which can represent itself. * * "&" is used to shift to modified BASE64 and "-" to shift back to US- * ASCII. All names start in US-ASCII, and MUST end in US-ASCII (that * is, a name that ends with a Unicode 16-bit octet MUST end with a "- * "). * * For example, here is a mailbox name which mixes English, Japanese, * and Chinese text: ~peter/mail/&ZeVnLIqe-/&U,BTFw- */ /* * Tests for US-ASCII characters belonging to character classes * defined in UTF-7. * * Set D (directly encoded characters) consists of the following * characters: the upper and lower case letters A through Z * and a through z, the 10 digits 0-9, and the following nine special * characters (note that "+" and "=" are omitted): * '(),-./:? * * Set O (optional direct characters) consists of the following * characters (note that "\" and "~" are omitted): * !"#$%&*;<=>@[]^_`{|} * * According to the rules in RFC 2152, the byte values for the following * US-ASCII characters are not used in UTF-7 and are therefore illegal: * - all C0 control codes except for CR LF TAB * - BACKSLASH * - TILDE * - DEL * - all codes beyond US-ASCII, i.e. all >127 */ /* uses '&' not '+' to start a base64 sequence */ #define AMPERSAND … #define COMMA … #define SLASH … /* legal byte values: all US-ASCII graphic characters 0x20..0x7e */ #define isLegalIMAP … /* direct-encode all of printable ASCII 0x20..0x7e except '&' 0x26 */ #define inSetDIMAP … #define TO_BASE64_IMAP … #define FROM_BASE64_IMAP … /* * converter status values: * * toUnicodeStatus: * 24 inDirectMode (boolean) * 23..16 base64Counter (-1..7) * 15..0 bits (up to 14 bits incoming base64) * * fromUnicodeStatus: * 24 inDirectMode (boolean) * 23..16 base64Counter (0..2) * 7..0 bits (6 bits outgoing base64) * * ignore bits 31..25 */ U_CDECL_BEGIN static void U_CALLCONV _IMAPToUnicodeWithOffsets(UConverterToUnicodeArgs *pArgs, UErrorCode *pErrorCode) { UConverter *cnv; const uint8_t *source, *sourceLimit; char16_t *target; const char16_t *targetLimit; int32_t *offsets; uint8_t *bytes; uint8_t byteIndex; int32_t length, targetCapacity; /* UTF-7 state */ uint16_t bits; int8_t base64Counter; UBool inDirectMode; int8_t base64Value; int32_t sourceIndex, nextSourceIndex; char16_t c; uint8_t b; /* set up the local pointers */ cnv=pArgs->converter; source=(const uint8_t *)pArgs->source; sourceLimit=(const uint8_t *)pArgs->sourceLimit; target=pArgs->target; targetLimit=pArgs->targetLimit; offsets=pArgs->offsets; /* get the state machine state */ { uint32_t status=cnv->toUnicodeStatus; inDirectMode=(UBool)((status>>24)&1); base64Counter=(int8_t)(status>>16); bits=(uint16_t)status; } bytes=cnv->toUBytes; byteIndex=cnv->toULength; /* sourceIndex=-1 if the current character began in the previous buffer */ sourceIndex=byteIndex==0 ? 0 : -1; nextSourceIndex=0; if(inDirectMode) { directMode: /* * In Direct Mode, US-ASCII characters are encoded directly, i.e., * with their US-ASCII byte values. * An ampersand starts Unicode (or "escape") Mode. * * In Direct Mode, only the sourceIndex is used. */ byteIndex=0; length=(int32_t)(sourceLimit-source); targetCapacity=(int32_t)(targetLimit-target); if(length>targetCapacity) { length=targetCapacity; } while(length>0) { b=*source++; if(!isLegalIMAP(b)) { /* illegal */ bytes[0]=b; byteIndex=1; *pErrorCode=U_ILLEGAL_CHAR_FOUND; break; } else if(b!=AMPERSAND) { /* write directly encoded character */ *target++=b; if(offsets!=nullptr) { *offsets++=sourceIndex++; } } else /* AMPERSAND */ { /* switch to Unicode mode */ nextSourceIndex=++sourceIndex; inDirectMode=false; byteIndex=0; bits=0; base64Counter=-1; goto unicodeMode; } --length; } if(source<sourceLimit && target>=targetLimit) { /* target is full */ *pErrorCode=U_BUFFER_OVERFLOW_ERROR; } } else { unicodeMode: /* * In Unicode (or "escape") Mode, UTF-16BE is base64-encoded. * The base64 sequence ends with any character that is not in the base64 alphabet. * A terminating minus sign is consumed. * US-ASCII must not be base64-ed. * * In Unicode Mode, the sourceIndex has the index to the start of the current * base64 bytes, while nextSourceIndex is precisely parallel to source, * keeping the index to the following byte. * Note that in 2 out of 3 cases, UChars overlap within a base64 byte. */ while(source<sourceLimit) { if(target<targetLimit) { bytes[byteIndex++]=b=*source++; ++nextSourceIndex; if(b>0x7e) { /* illegal - test other illegal US-ASCII values by base64Value==-3 */ inDirectMode=true; *pErrorCode=U_ILLEGAL_CHAR_FOUND; break; } else if((base64Value=FROM_BASE64_IMAP(b))>=0) { /* collect base64 bytes into UChars */ switch(base64Counter) { case -1: /* -1 is immediately after the & */ case 0: bits=base64Value; base64Counter=1; break; case 1: case 3: case 4: case 6: bits=(uint16_t)((bits<<6)|base64Value); ++base64Counter; break; case 2: c=(char16_t)((bits<<4)|(base64Value>>2)); if(isLegalIMAP(c)) { /* illegal */ inDirectMode=true; *pErrorCode=U_ILLEGAL_CHAR_FOUND; goto endloop; } *target++=c; if(offsets!=nullptr) { *offsets++=sourceIndex; sourceIndex=nextSourceIndex-1; } bytes[0]=b; /* keep this byte in case an error occurs */ byteIndex=1; bits=(uint16_t)(base64Value&3); base64Counter=3; break; case 5: c=(char16_t)((bits<<2)|(base64Value>>4)); if(isLegalIMAP(c)) { /* illegal */ inDirectMode=true; *pErrorCode=U_ILLEGAL_CHAR_FOUND; goto endloop; } *target++=c; if(offsets!=nullptr) { *offsets++=sourceIndex; sourceIndex=nextSourceIndex-1; } bytes[0]=b; /* keep this byte in case an error occurs */ byteIndex=1; bits=(uint16_t)(base64Value&15); base64Counter=6; break; case 7: c=(char16_t)((bits<<6)|base64Value); if(isLegalIMAP(c)) { /* illegal */ inDirectMode=true; *pErrorCode=U_ILLEGAL_CHAR_FOUND; goto endloop; } *target++=c; if(offsets!=nullptr) { *offsets++=sourceIndex; sourceIndex=nextSourceIndex; } byteIndex=0; bits=0; base64Counter=0; break; default: /* will never occur */ break; } } else if(base64Value==-2) { /* minus sign terminates the base64 sequence */ inDirectMode=true; if(base64Counter==-1) { /* &- i.e. a minus immediately following an ampersand */ *target++=AMPERSAND; if(offsets!=nullptr) { *offsets++=sourceIndex-1; } } else { /* absorb the minus and leave the Unicode Mode */ if(bits!=0 || (base64Counter!=0 && base64Counter!=3 && base64Counter!=6)) { /* bits are illegally left over, a char16_t is incomplete */ /* base64Counter other than 0, 3, 6 means non-minimal zero-padding, also illegal */ *pErrorCode=U_ILLEGAL_CHAR_FOUND; break; } } sourceIndex=nextSourceIndex; goto directMode; } else { if(base64Counter==-1) { /* illegal: & immediately followed by something other than base64 or minus sign */ /* include the ampersand in the reported sequence */ --sourceIndex; bytes[0]=AMPERSAND; bytes[1]=b; byteIndex=2; } /* base64Value==-1 for characters that are illegal only in Unicode mode */ /* base64Value==-3 for illegal characters */ /* illegal */ inDirectMode=true; *pErrorCode=U_ILLEGAL_CHAR_FOUND; break; } } else { /* target is full */ *pErrorCode=U_BUFFER_OVERFLOW_ERROR; break; } } } endloop: /* * the end of the input stream and detection of truncated input * are handled by the framework, but here we must check if we are in Unicode * mode and byteIndex==0 because we must end in direct mode * * conditions: * successful * in Unicode mode and byteIndex==0 * end of input and no truncated input */ if( U_SUCCESS(*pErrorCode) && !inDirectMode && byteIndex==0 && pArgs->flush && source>=sourceLimit ) { if(base64Counter==-1) { /* & at the very end of the input */ /* make the ampersand the reported sequence */ bytes[0]=AMPERSAND; byteIndex=1; } /* else if(base64Counter!=-1) byteIndex remains 0 because there is no particular byte sequence */ inDirectMode=true; /* avoid looping */ *pErrorCode=U_TRUNCATED_CHAR_FOUND; } /* set the converter state back into UConverter */ cnv->toUnicodeStatus=((uint32_t)inDirectMode<<24)|((uint32_t)((uint8_t)base64Counter)<<16)|(uint32_t)bits; cnv->toULength=byteIndex; /* write back the updated pointers */ pArgs->source=(const char *)source; pArgs->target=target; pArgs->offsets=offsets; } static void U_CALLCONV _IMAPFromUnicodeWithOffsets(UConverterFromUnicodeArgs *pArgs, UErrorCode *pErrorCode) { UConverter *cnv; const char16_t *source, *sourceLimit; uint8_t *target, *targetLimit; int32_t *offsets; int32_t length, targetCapacity, sourceIndex; char16_t c; uint8_t b; /* UTF-7 state */ uint8_t bits; int8_t base64Counter; UBool inDirectMode; /* set up the local pointers */ cnv=pArgs->converter; /* set up the local pointers */ source=pArgs->source; sourceLimit=pArgs->sourceLimit; target=(uint8_t *)pArgs->target; targetLimit=(uint8_t *)pArgs->targetLimit; offsets=pArgs->offsets; /* get the state machine state */ { uint32_t status=cnv->fromUnicodeStatus; inDirectMode=(UBool)((status>>24)&1); base64Counter=(int8_t)(status>>16); bits=(uint8_t)status; } /* UTF-7 always encodes UTF-16 code units, therefore we need only a simple sourceIndex */ sourceIndex=0; if(inDirectMode) { directMode: length=(int32_t)(sourceLimit-source); targetCapacity=(int32_t)(targetLimit-target); if(length>targetCapacity) { length=targetCapacity; } while(length>0) { c=*source++; /* encode 0x20..0x7e except '&' directly */ if(inSetDIMAP(c)) { /* encode directly */ *target++=(uint8_t)c; if(offsets!=nullptr) { *offsets++=sourceIndex++; } } else if(c==AMPERSAND) { /* output &- for & */ *target++=AMPERSAND; if(target<targetLimit) { *target++=MINUS; if(offsets!=nullptr) { *offsets++=sourceIndex; *offsets++=sourceIndex++; } /* realign length and targetCapacity */ goto directMode; } else { if(offsets!=nullptr) { *offsets++=sourceIndex++; } cnv->charErrorBuffer[0]=MINUS; cnv->charErrorBufferLength=1; *pErrorCode=U_BUFFER_OVERFLOW_ERROR; break; } } else { /* un-read this character and switch to Unicode Mode */ --source; *target++=AMPERSAND; if(offsets!=nullptr) { *offsets++=sourceIndex; } inDirectMode=false; base64Counter=0; goto unicodeMode; } --length; } if(source<sourceLimit && target>=targetLimit) { /* target is full */ *pErrorCode=U_BUFFER_OVERFLOW_ERROR; } } else { unicodeMode: while(source<sourceLimit) { if(target<targetLimit) { c=*source++; if(isLegalIMAP(c)) { /* encode directly */ inDirectMode=true; /* trick: back out this character to make this easier */ --source; /* terminate the base64 sequence */ if(base64Counter!=0) { /* write remaining bits for the previous character */ *target++=TO_BASE64_IMAP(bits); if(offsets!=nullptr) { *offsets++=sourceIndex-1; } } /* need to terminate with a minus */ if(target<targetLimit) { *target++=MINUS; if(offsets!=nullptr) { *offsets++=sourceIndex-1; } } else { cnv->charErrorBuffer[0]=MINUS; cnv->charErrorBufferLength=1; *pErrorCode=U_BUFFER_OVERFLOW_ERROR; break; } goto directMode; } else { /* * base64 this character: * Output 2 or 3 base64 bytes for the remaining bits of the previous character * and the bits of this character, each implicitly in UTF-16BE. * * Here, bits is an 8-bit variable because only 6 bits need to be kept from one * character to the next. The actual 2 or 4 bits are shifted to the left edge * of the 6-bits field 5..0 to make the termination of the base64 sequence easier. */ switch(base64Counter) { case 0: b=(uint8_t)(c>>10); *target++=TO_BASE64_IMAP(b); if(target<targetLimit) { b=(uint8_t)((c>>4)&0x3f); *target++=TO_BASE64_IMAP(b); if(offsets!=nullptr) { *offsets++=sourceIndex; *offsets++=sourceIndex++; } } else { if(offsets!=nullptr) { *offsets++=sourceIndex++; } b=(uint8_t)((c>>4)&0x3f); cnv->charErrorBuffer[0]=TO_BASE64_IMAP(b); cnv->charErrorBufferLength=1; *pErrorCode=U_BUFFER_OVERFLOW_ERROR; } bits=(uint8_t)((c&15)<<2); base64Counter=1; break; case 1: b=(uint8_t)(bits|(c>>14)); *target++=TO_BASE64_IMAP(b); if(target<targetLimit) { b=(uint8_t)((c>>8)&0x3f); *target++=TO_BASE64_IMAP(b); if(target<targetLimit) { b=(uint8_t)((c>>2)&0x3f); *target++=TO_BASE64_IMAP(b); if(offsets!=nullptr) { *offsets++=sourceIndex; *offsets++=sourceIndex; *offsets++=sourceIndex++; } } else { if(offsets!=nullptr) { *offsets++=sourceIndex; *offsets++=sourceIndex++; } b=(uint8_t)((c>>2)&0x3f); cnv->charErrorBuffer[0]=TO_BASE64_IMAP(b); cnv->charErrorBufferLength=1; *pErrorCode=U_BUFFER_OVERFLOW_ERROR; } } else { if(offsets!=nullptr) { *offsets++=sourceIndex++; } b=(uint8_t)((c>>8)&0x3f); cnv->charErrorBuffer[0]=TO_BASE64_IMAP(b); b=(uint8_t)((c>>2)&0x3f); cnv->charErrorBuffer[1]=TO_BASE64_IMAP(b); cnv->charErrorBufferLength=2; *pErrorCode=U_BUFFER_OVERFLOW_ERROR; } bits=(uint8_t)((c&3)<<4); base64Counter=2; break; case 2: b=(uint8_t)(bits|(c>>12)); *target++=TO_BASE64_IMAP(b); if(target<targetLimit) { b=(uint8_t)((c>>6)&0x3f); *target++=TO_BASE64_IMAP(b); if(target<targetLimit) { b=(uint8_t)(c&0x3f); *target++=TO_BASE64_IMAP(b); if(offsets!=nullptr) { *offsets++=sourceIndex; *offsets++=sourceIndex; *offsets++=sourceIndex++; } } else { if(offsets!=nullptr) { *offsets++=sourceIndex; *offsets++=sourceIndex++; } b=(uint8_t)(c&0x3f); cnv->charErrorBuffer[0]=TO_BASE64_IMAP(b); cnv->charErrorBufferLength=1; *pErrorCode=U_BUFFER_OVERFLOW_ERROR; } } else { if(offsets!=nullptr) { *offsets++=sourceIndex++; } b=(uint8_t)((c>>6)&0x3f); cnv->charErrorBuffer[0]=TO_BASE64_IMAP(b); b=(uint8_t)(c&0x3f); cnv->charErrorBuffer[1]=TO_BASE64_IMAP(b); cnv->charErrorBufferLength=2; *pErrorCode=U_BUFFER_OVERFLOW_ERROR; } bits=0; base64Counter=0; break; default: /* will never occur */ break; } } } else { /* target is full */ *pErrorCode=U_BUFFER_OVERFLOW_ERROR; break; } } } if(pArgs->flush && source>=sourceLimit) { /* flush remaining bits to the target */ if(!inDirectMode) { if(base64Counter!=0) { if(target<targetLimit) { *target++=TO_BASE64_IMAP(bits); if(offsets!=nullptr) { *offsets++=sourceIndex-1; } } else { cnv->charErrorBuffer[cnv->charErrorBufferLength++]=TO_BASE64_IMAP(bits); *pErrorCode=U_BUFFER_OVERFLOW_ERROR; } } /* need to terminate with a minus */ if(target<targetLimit) { *target++=MINUS; if(offsets!=nullptr) { *offsets++=sourceIndex-1; } } else { cnv->charErrorBuffer[cnv->charErrorBufferLength++]=MINUS; *pErrorCode=U_BUFFER_OVERFLOW_ERROR; } } /* reset the state for the next conversion */ cnv->fromUnicodeStatus=(cnv->fromUnicodeStatus&0xf0000000)|0x1000000; /* keep version, inDirectMode=true */ } else { /* set the converter state back into UConverter */ cnv->fromUnicodeStatus= (cnv->fromUnicodeStatus&0xf0000000)| /* keep version*/ ((uint32_t)inDirectMode<<24)|((uint32_t)base64Counter<<16)|(uint32_t)bits; } /* write back the updated pointers */ pArgs->source=source; pArgs->target=(char *)target; pArgs->offsets=offsets; } U_CDECL_END static const UConverterImpl _IMAPImpl={ UCNV_IMAP_MAILBOX, nullptr, nullptr, _UTF7Open, nullptr, _UTF7Reset, _IMAPToUnicodeWithOffsets, _IMAPToUnicodeWithOffsets, _IMAPFromUnicodeWithOffsets, _IMAPFromUnicodeWithOffsets, nullptr, nullptr, nullptr, nullptr, /* we don't need writeSub() because we never call a callback at fromUnicode() */ nullptr, ucnv_getCompleteUnicodeSet, nullptr, nullptr }; static const UConverterStaticData _IMAPStaticData={ sizeof(UConverterStaticData), "IMAP-mailbox-name", 0, /* TODO CCSID for IMAP-mailbox-name */ UCNV_IBM, UCNV_IMAP_MAILBOX, 1, 4, { 0x3f, 0, 0, 0 }, 1, /* the subchar is not used */ false, false, 0, 0, { 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0 } /* reserved */ }; const UConverterSharedData _IMAPData= UCNV_IMMUTABLE_SHARED_DATA_INITIALIZER(&_IMAPStaticData, &_IMAPImpl); #endif
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