X-Git-Url: https://diplodocus.org/git/nmh/blobdiff_plain/628b193daced4357675de5127ff8129cf6f81b0f..94187a80bd60baab4b9c4b949ad820d730578123:/sbr/base64.c?ds=sidebyside diff --git a/sbr/base64.c b/sbr/base64.c index 2fbef4b0..cbd225de 100644 --- a/sbr/base64.c +++ b/sbr/base64.c @@ -1,5 +1,4 @@ -/* - * base64.c -- routines for converting to base64 +/* base64.c -- routines for converting to base64 * * This code is Copyright (c) 2012, by the authors of nmh. See the * COPYRIGHT file in the root directory of the nmh distribution for @@ -8,10 +7,23 @@ #include #include +#include +#include -static char nib2b64[0x40+1] = +static const char nib2b64[0x40+1] = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/"; +/* + * Copy data from one file to another, converting to base64-encoding. + * + * Arguments include: + * + * in - Input filehandle (unencoded data) + * out - Output filename (base64-encoded data) + * crlf - If set, output encoded CRLF for every LF on input. + * + * Returns OK on success, NOTOK otherwise. + */ int writeBase64aux (FILE *in, FILE *out, int crlf) { @@ -83,7 +95,10 @@ writeBase64aux (FILE *in, FILE *out, int crlf) outbuf[2] = '='; } - fwrite (outbuf, sizeof(*outbuf), sizeof(outbuf), out); + if (fwrite (outbuf, sizeof(*outbuf), sizeof(outbuf), out) < + sizeof outbuf) { + advise ("writeBase64aux", "fwrite"); + } if (cc < sizeof(inbuf)) { putc ('\n', out); @@ -108,7 +123,7 @@ writeBase64aux (FILE *in, FILE *out, int crlf) 4 * [length/3] + length/57 + 2 But double the length will certainly be sufficient. */ int -writeBase64 (unsigned char *in, size_t length, unsigned char *out) +writeBase64 (const unsigned char *in, size_t length, unsigned char *out) { unsigned int n = BPERLIN; @@ -116,20 +131,19 @@ writeBase64 (unsigned char *in, size_t length, unsigned char *out) unsigned long bits; unsigned char *bp; unsigned int cc; - for (cc = 0, bp = in; length > 0 && cc < 3; ++cc, ++bp, --length) + for (cc = 0; length > 0 && cc < 3; ++cc, --length) /* empty */ ; - if (cc == 0) { + if (cc == 0) break; - } else { - bits = (in[0] & 0xff) << 16; - if (cc > 1) { - bits |= (in[1] & 0xff) << 8; - if (cc > 2) { - bits |= in[2] & 0xff; - } - } - } + + bits = (in[0] & 0xff) << 16; + if (cc > 1) { + bits |= (in[1] & 0xff) << 8; + if (cc > 2) { + bits |= in[2] & 0xff; + } + } for (bp = out + 4; bp > out; bits >>= 6) *--bp = nib2b64[bits & 0x3f]; @@ -157,32 +171,31 @@ writeBase64 (unsigned char *in, size_t length, unsigned char *out) return OK; } -/* +/* * Essentially a duplicate of writeBase64, but without line wrapping or * newline termination (note: string IS NUL terminated) */ int -writeBase64raw (unsigned char *in, size_t length, unsigned char *out) +writeBase64raw (const unsigned char *in, size_t length, unsigned char *out) { while (1) { unsigned long bits; unsigned char *bp; unsigned int cc; - for (cc = 0, bp = in; length > 0 && cc < 3; ++cc, ++bp, --length) + for (cc = 0; length > 0 && cc < 3; ++cc, --length) /* empty */ ; - if (cc == 0) { + if (cc == 0) break; - } else { - bits = (in[0] & 0xff) << 16; - if (cc > 1) { - bits |= (in[1] & 0xff) << 8; - if (cc > 2) { - bits |= in[2] & 0xff; - } - } - } + + bits = (in[0] & 0xff) << 16; + if (cc > 1) { + bits |= (in[1] & 0xff) << 8; + if (cc > 2) { + bits |= in[2] & 0xff; + } + } for (bp = out + 4; bp > out; bits >>= 6) *--bp = nib2b64[bits & 0x3f]; @@ -202,3 +215,163 @@ writeBase64raw (unsigned char *in, size_t length, unsigned char *out) return OK; } + + +static const unsigned char b642nib[0x80] = { + 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, + 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, + 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, + 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, + 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, + 0xff, 0xff, 0xff, 0x3e, 0xff, 0xff, 0xff, 0x3f, + 0x34, 0x35, 0x36, 0x37, 0x38, 0x39, 0x3a, 0x3b, + 0x3c, 0x3d, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, + 0xff, 0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, + 0x07, 0x08, 0x09, 0x0a, 0x0b, 0x0c, 0x0d, 0x0e, + 0x0f, 0x10, 0x11, 0x12, 0x13, 0x14, 0x15, 0x16, + 0x17, 0x18, 0x19, 0xff, 0xff, 0xff, 0xff, 0xff, + 0xff, 0x1a, 0x1b, 0x1c, 0x1d, 0x1e, 0x1f, 0x20, + 0x21, 0x22, 0x23, 0x24, 0x25, 0x26, 0x27, 0x28, + 0x29, 0x2a, 0x2b, 0x2c, 0x2d, 0x2e, 0x2f, 0x30, + 0x31, 0x32, 0x33, 0xff, 0xff, 0xff, 0xff, 0xff +}; + +/* + * Decode a base64 string. The result, decoded, must be freed by the caller. + * + * encoded - the string to be decoded + * decoded - the decoded bytes + * len - number of decoded bytes + * skip-crs - non-zero for text content, and for which CR's should be + * skipped + * digest - for an MD5 digest, it can be null + */ +int +decodeBase64 (const char *encoded, unsigned char **decoded, size_t *len, + int skip_crs, unsigned char *digest) { + const char *cp = encoded; + int self_delimiting = 0; + int bitno, skip; + uint32_t bits; + /* Size the decoded string very conservatively. */ + charstring_t decoded_c = charstring_create (strlen (encoded)); + MD5_CTX mdContext; + + if (digest) + MD5Init (&mdContext); + + bitno = 18; + bits = 0L; + skip = 0; + + for (; *cp; ++cp) { + switch (*cp) { + unsigned char value; + + default: + if (isspace ((unsigned char) *cp)) { + break; + } + if (skip || (((unsigned char) *cp) & 0x80) || + (value = b642nib[((unsigned char) *cp) & 0x7f]) > 0x3f) { + inform("invalid base64 byte %#x: %.42s", + *(unsigned char *)cp, cp); + charstring_free (decoded_c); + *decoded = NULL; + + return NOTOK; + } + + bits |= value << bitno; +test_end: + if ((bitno -= 6) < 0) { + char b = (char) ((bits >> 16) & 0xff); + + if (! skip_crs || b != '\r') { + charstring_push_back (decoded_c, b); + } + if (digest) + MD5Update (&mdContext, (unsigned char *) &b, 1); + if (skip < 2) { + b = (bits >> 8) & 0xff; + if (! skip_crs || b != '\r') { + charstring_push_back (decoded_c, b); + } + if (digest) + MD5Update (&mdContext, (unsigned char *) &b, 1); + if (skip < 1) { + b = bits & 0xff; + if (! skip_crs || b != '\r') { + charstring_push_back (decoded_c, b); + } + if (digest) + MD5Update (&mdContext, (unsigned char *) &b, 1); + } + } + + bitno = 18; + bits = 0L; + skip = 0; + } + break; + + case '=': + if (++skip <= 3) + goto test_end; + self_delimiting = 1; + break; + } + } + + if (! self_delimiting && bitno != 18) { + /* Show some context for the error. */ + cp -= min(cp - encoded, 20); + inform("premature ending (bitno %d) near %s", bitno, cp); + charstring_free (decoded_c); + *decoded = NULL; + + return NOTOK; + } + + *decoded = (unsigned char *) charstring_buffer_copy (decoded_c); + *len = charstring_bytes (decoded_c); + charstring_free (decoded_c); + + if (digest) { + MD5Final (digest, &mdContext); + } + + return OK; +} + + +/* + * Prepare an unsigned char array for display by replacing non-printable + * ASCII bytes with their hex representation. Assumes ASCII input. output + * is allocated by the function and must be freed by the caller. + */ +void +hexify (const unsigned char *input, size_t len, char **output) { + /* Start with a charstring capacity that's arbitrarily larger than len. */ + const charstring_t tmp = charstring_create (2 * len); + const unsigned char *cp = input; + size_t i; + + for (i = 0; i < len; ++i, ++cp) { + if (isascii(*cp) && isprint(*cp)) { + charstring_push_back (tmp, (const char) *cp); + } else { + char s[16]; + const int num = snprintf(s, sizeof s, "[0x%02x]", *cp); + + if (num <= 0 || (unsigned int) num >= sizeof s) { + inform("hexify failed to write nonprintable character, needed %d bytes", num + 1); + } else { + charstring_append_cstring (tmp, s); + } + } + } + + *output = charstring_buffer_copy (tmp); + charstring_free (tmp); +}