X-Git-Url: https://diplodocus.org/git/nmh/blobdiff_plain/6ba5b855ebc737cc46cabfbe799b0c7706f437f4..dbbbe1b73d4eba1f4d0d55ccab54f2f7130f395d:/sbr/base64.c diff --git a/sbr/base64.c b/sbr/base64.c index 5ff9f53c..eb3c8ea2 100644 --- a/sbr/base64.c +++ b/sbr/base64.c @@ -8,15 +8,18 @@ #include #include +#include +#include static char nib2b64[0x40+1] = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/"; int -writeBase64aux (FILE *in, FILE *out) +writeBase64aux (FILE *in, FILE *out, int crlf) { unsigned int cc, n; - char inbuf[3]; + unsigned char inbuf[3]; + int skipnl = 0; n = BPERLIN; while ((cc = fread (inbuf, sizeof(*inbuf), sizeof(inbuf), in)) > 0) { @@ -29,6 +32,47 @@ writeBase64aux (FILE *in, FILE *out) if (cc < sizeof(inbuf) - 1) inbuf[1] = 0; } + + /* + * Convert a LF to a CRLF if desired. That means we need to push + * data back into the input stream. + */ + + if (crlf) { + unsigned int i; + + for (i = 0; i < cc; i++) { + if (inbuf[i] == '\n' && !skipnl) { + inbuf[i] = '\r'; + /* + * If it's the last character in the buffer, we can just + * substitute a \r and push a \n back. Otherwise shuffle + * everything down and push the last character back. + */ + if (i == cc - 1) { + /* + * If we're at the end of the input, there might be + * more room in inbuf; if so, add it there. Otherwise + * push it back to the input. + */ + if (cc < sizeof(inbuf)) + inbuf[cc++] = '\n'; + else + ungetc('\n', in); + skipnl = 1; + } else { + /* This only works as long as sizeof(inbuf) == 3 */ + ungetc(inbuf[cc - 1], in); + if (cc == 3 && i == 0) + inbuf[2] = inbuf[1]; + inbuf[++i] = '\n'; + } + } else { + skipnl = 0; + } + } + } + bits = (inbuf[0] & 0xff) << 16; bits |= (inbuf[1] & 0xff) << 8; bits |= inbuf[2] & 0xff; @@ -41,7 +85,10 @@ writeBase64aux (FILE *in, FILE *out) 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); @@ -115,7 +162,7 @@ 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) */ @@ -160,3 +207,152 @@ writeBase64raw (unsigned char *in, size_t length, unsigned char *out) return OK; } + + +static 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. + * See description of arguments with declaration in h/prototypes.h. + */ +int +decodeBase64 (const char *encoded, const 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) { + advise (NULL, "invalid BASE64 encoding in %s", encoded); + 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) { + self_delimiting = 1; + break; + } else { + goto test_end; + } + } + } + + if (! self_delimiting && bitno != 18) { + advise (NULL, "premature ending (bitno %d) in %s", bitno, encoded); + charstring_free (decoded_c); + *decoded = NULL; + + return NOTOK; + } + + *decoded = 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) { + advise (NULL, "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); +}