X-Git-Url: https://git.stg.codes/stg.git/blobdiff_plain/8c6fa3fbaccc22127280bf77a48fab5a3ee0716e..46b0747592074017ff0ea4b33d4a7194235886e5:/libs/smux/per_support.c diff --git a/libs/smux/per_support.c b/libs/smux/per_support.c new file mode 100644 index 00000000..c8344193 --- /dev/null +++ b/libs/smux/per_support.c @@ -0,0 +1,318 @@ +/* + * Copyright (c) 2005, 2006 Lev Walkin . All rights reserved. + * Redistribution and modifications are permitted subject to BSD license. + */ +#include +#include +#include + +/* + * Extract a small number of bits (<= 31) from the specified PER data pointer. + */ +int32_t +per_get_few_bits(asn_per_data_t *pd, int nbits) { + size_t off; /* Next after last bit offset */ + uint32_t accum; + const uint8_t *buf; + + if(nbits < 0 || pd->nboff + nbits > pd->nbits) + return -1; + + ASN_DEBUG("[PER get %d bits from %p+%d bits]", + nbits, pd->buffer, pd->nboff); + + /* + * Normalize position indicator. + */ + if(pd->nboff >= 8) { + pd->buffer += (pd->nboff >> 3); + pd->nbits -= (pd->nboff & ~0x07); + pd->nboff &= 0x07; + } + off = (pd->nboff += nbits); + buf = pd->buffer; + + /* + * Extract specified number of bits. + */ + if(off <= 8) + accum = nbits ? (buf[0]) >> (8 - off) : 0; + else if(off <= 16) + accum = ((buf[0] << 8) + buf[1]) >> (16 - off); + else if(off <= 24) + accum = ((buf[0] << 16) + (buf[1] << 8) + buf[2]) >> (24 - off); + else if(off <= 31) + accum = ((buf[0] << 24) + (buf[1] << 16) + + (buf[2] << 8) + (buf[3])) >> (32 - off); + else if(nbits <= 31) { + asn_per_data_t tpd = *pd; + /* Here are we with our 31-bits limit plus 1..7 bits offset. */ + tpd.nboff -= nbits; + accum = per_get_few_bits(&tpd, nbits - 24) << 24; + accum |= per_get_few_bits(&tpd, 24); + } else { + pd->nboff -= nbits; /* Oops, revert back */ + return -1; + } + + return (accum & (((uint32_t)1 << nbits) - 1)); +} + +/* + * Extract a large number of bits from the specified PER data pointer. + */ +int +per_get_many_bits(asn_per_data_t *pd, uint8_t *dst, int alright, int nbits) { + int32_t value; + + if(alright && (nbits & 7)) { + /* Perform right alignment of a first few bits */ + value = per_get_few_bits(pd, nbits & 0x07); + if(value < 0) return -1; + *dst++ = value; /* value is already right-aligned */ + nbits &= ~7; + } + + while(nbits) { + if(nbits >= 24) { + value = per_get_few_bits(pd, 24); + if(value < 0) return -1; + *(dst++) = value >> 16; + *(dst++) = value >> 8; + *(dst++) = value; + nbits -= 24; + } else { + value = per_get_few_bits(pd, nbits); + if(value < 0) return -1; + if(nbits & 7) { /* implies left alignment */ + value <<= 8 - (nbits & 7), + nbits += 8 - (nbits & 7); + if(nbits > 24) + *dst++ = value >> 24; + } + if(nbits > 16) + *dst++ = value >> 16; + if(nbits > 8) + *dst++ = value >> 8; + *dst++ = value; + break; + } + } + + return 0; +} + +/* + * Get the length "n" from the stream. + */ +ssize_t +uper_get_length(asn_per_data_t *pd, int ebits, int *repeat) { + ssize_t value; + + *repeat = 0; + + if(ebits >= 0) return per_get_few_bits(pd, ebits); + + value = per_get_few_bits(pd, 8); + if(value < 0) return -1; + if((value & 128) == 0) /* #10.9.3.6 */ + return (value & 0x7F); + if((value & 64) == 0) { /* #10.9.3.7 */ + value = ((value & 63) << 8) | per_get_few_bits(pd, 8); + if(value < 0) return -1; + return value; + } + value &= 63; /* this is "m" from X.691, #10.9.3.8 */ + if(value < 1 || value > 4) + return -1; + *repeat = 1; + return (16384 * value); +} + +/* + * Get the normally small non-negative whole number. + * X.691, #10.6 + */ +ssize_t +uper_get_nsnnwn(asn_per_data_t *pd) { + ssize_t value; + + value = per_get_few_bits(pd, 7); + if(value & 64) { /* implicit (value < 0) */ + value &= 63; + value <<= 2; + value |= per_get_few_bits(pd, 2); + if(value & 128) /* implicit (value < 0) */ + return -1; + if(value == 0) + return 0; + if(value >= 3) + return -1; + value = per_get_few_bits(pd, 8 * value); + return value; + } + + return value; +} + +/* + * Put the normally small non-negative whole number. + * X.691, #10.6 + */ +int +uper_put_nsnnwn(asn_per_outp_t *po, int n) { + int bytes; + + if(n <= 63) { + if(n < 0) return -1; + return per_put_few_bits(po, n, 7); + } + if(n < 256) + bytes = 1; + else if(n < 65536) + bytes = 2; + else if(n < 256 * 65536) + bytes = 3; + else + return -1; /* This is not a "normally small" value */ + if(per_put_few_bits(po, bytes, 8)) + return -1; + + return per_put_few_bits(po, n, 8 * bytes); +} + + +/* + * Put a small number of bits (<= 31). + */ +int +per_put_few_bits(asn_per_outp_t *po, uint32_t bits, int obits) { + size_t off; /* Next after last bit offset */ + size_t omsk; /* Existing last byte meaningful bits mask */ + uint8_t *buf; + + if(obits <= 0 || obits >= 32) return obits ? -1 : 0; + + ASN_DEBUG("[PER put %d bits to %p+%d bits]", + obits, po->buffer, po->nboff); + + /* + * Normalize position indicator. + */ + if(po->nboff >= 8) { + po->buffer += (po->nboff >> 3); + po->nbits -= (po->nboff & ~0x07); + po->nboff &= 0x07; + } + + /* + * Flush whole-bytes output, if necessary. + */ + if(po->nboff + obits > po->nbits) { + int complete_bytes = (po->buffer - po->tmpspace); + if(po->outper(po->buffer, complete_bytes, po->op_key) < 0) + return -1; + if(po->nboff) + po->tmpspace[0] = po->buffer[0]; + po->buffer = po->tmpspace; + po->nbits = 8 * sizeof(po->tmpspace); + po->flushed_bytes += complete_bytes; + } + + /* + * Now, due to sizeof(tmpspace), we are guaranteed large enough space. + */ + buf = po->buffer; + omsk = ~((1 << (8 - po->nboff)) - 1); + off = (po->nboff += obits); + + /* Clear data of debris before meaningful bits */ + bits &= (((uint32_t)1 << obits) - 1); + + ASN_DEBUG("[PER out %d %u/%x (t=%d,o=%d) %x&%x=%x]", obits, bits, bits, + po->nboff - obits, off, buf[0], omsk&0xff, buf[0] & omsk); + + if(off <= 8) /* Completely within 1 byte */ + bits <<= (8 - off), + buf[0] = (buf[0] & omsk) | bits; + else if(off <= 16) + bits <<= (16 - off), + buf[0] = (buf[0] & omsk) | (bits >> 8), + buf[1] = bits; + else if(off <= 24) + bits <<= (24 - off), + buf[0] = (buf[0] & omsk) | (bits >> 16), + buf[1] = bits >> 8, + buf[2] = bits; + else if(off <= 31) + bits <<= (32 - off), + buf[0] = (buf[0] & omsk) | (bits >> 24), + buf[1] = bits >> 16, + buf[2] = bits >> 8, + buf[3] = bits; + else { + ASN_DEBUG("->[PER out split %d]", obits); + per_put_few_bits(po, bits >> 8, 24); + per_put_few_bits(po, bits, obits - 24); + ASN_DEBUG("<-[PER out split %d]", obits); + } + + ASN_DEBUG("[PER out %u/%x => %02x buf+%d]", + bits, bits, buf[0], po->buffer - po->tmpspace); + + return 0; +} + + +/* + * Output a large number of bits. + */ +int +per_put_many_bits(asn_per_outp_t *po, const uint8_t *src, int nbits) { + + while(nbits) { + uint32_t value; + + if(nbits >= 24) { + value = (src[0] << 16) | (src[1] << 8) | src[2]; + src += 3; + nbits -= 24; + if(per_put_few_bits(po, value, 24)) + return -1; + } else { + value = src[0]; + if(nbits > 8) + value = (value << 8) | src[1]; + if(nbits > 16) + value = (value << 8) | src[2]; + if(nbits & 0x07) + value >>= (8 - (nbits & 0x07)); + if(per_put_few_bits(po, value, nbits)) + return -1; + break; + } + } + + return 0; +} + +/* + * Put the length "n" (or part of it) into the stream. + */ +ssize_t +uper_put_length(asn_per_outp_t *po, size_t length) { + + if(length <= 127) /* #10.9.3.6 */ + return per_put_few_bits(po, length, 8) + ? -1 : (ssize_t)length; + else if(length < 16384) /* #10.9.3.7 */ + return per_put_few_bits(po, length|0x8000, 16) + ? -1 : (ssize_t)length; + + length >>= 14; + if(length > 4) length = 4; + + return per_put_few_bits(po, 0xC0 | length, 8) + ? -1 : (ssize_t)(length << 14); +} +