1 #include "first.h" 2 3 #include "base64.h" 4 5 /* reverse mapping: 6 * >= 0: base64 value 7 * -1: invalid character 8 * -2: skip character (whitespace/control) 9 * -3: padding 10 */ 11 12 /* BASE64_STANDARD: "A-Z a-z 0-9 + /" maps to 0-63, pad with "=" */ 13 static const char base64_standard_table[] = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/="; 14 static const signed char base64_standard_reverse_table[] = { 15 /* 0 1 2 3 4 5 6 7 8 9 A B C D E F */ 16 -1, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, /* 0x00 - 0x0F */ 17 -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, /* 0x10 - 0x1F */ 18 -2, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, 62, -1, -1, -1, 63, /* 0x20 - 0x2F */ 19 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, -1, -1, -1, -3, -1, -1, /* 0x30 - 0x3F */ 20 -1, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, /* 0x40 - 0x4F */ 21 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, -1, -1, -1, -1, -1, /* 0x50 - 0x5F */ 22 -1, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, /* 0x60 - 0x6F */ 23 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, -1, -1, -1, -1, -1, /* 0x70 - 0x7F */ 24 }; 25 26 /* BASE64_URL: "A-Z a-z 0-9 - _" maps to 0-63, pad with "=" */ 27 static const char base64_url_table[] = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789-_="; 28 static const signed char base64_url_reverse_table[] = { 29 /* 0 1 2 3 4 5 6 7 8 9 A B C D E F */ 30 -1, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, /* 0x00 - 0x0F */ 31 -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, /* 0x10 - 0x1F */ 32 -2, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, 62, -1, -1, /* 0x20 - 0x2F */ 33 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, -1, -1, -1, -3, -1, -1, /* 0x30 - 0x3F */ 34 -1, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, /* 0x40 - 0x4F */ 35 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, -1, -1, -1, -1, 63, /* 0x50 - 0x5F */ 36 -1, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, /* 0x60 - 0x6F */ 37 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, -1, -1, -1, -1, -1, /* 0x70 - 0x7F */ 38 }; 39 40 size_t li_base64_dec(unsigned char * const result, const size_t out_length, const char * const in, const size_t in_length, const base64_charset charset) { 41 size_t i; 42 const signed char * const base64_reverse_table = (charset) 43 ? base64_url_reverse_table /* BASE64_URL */ 44 : base64_standard_reverse_table; /* BASE64_STANDARD */ 45 46 int_fast32_t ch = 0; 47 int_fast32_t out4 = 0; 48 size_t out_pos = 0; 49 for (i = 0; i < in_length; i++) { 50 const uint_fast32_t c = ((unsigned char *)in)[i]; 51 ch = (c < 128) ? base64_reverse_table[c] : -1; 52 if (__builtin_expect( (ch < 0), 0)) { 53 /* skip formatted base64; skip whitespace ('\r' '\n' '\t' ' ')*/ 54 if (-2 == ch) /*(loose check; skip ' ', all ctrls not \127 or \0)*/ 55 continue; /* skip character */ 56 break; 57 } 58 59 out4 = (out4 << 6) | ch; 60 if ((i & 3) == 3) { 61 result[out_pos] = (out4 >> 16) & 0xFF; 62 result[out_pos+1] = (out4 >> 8) & 0xFF; 63 result[out_pos+2] = (out4 ) & 0xFF; 64 out_pos += 3; 65 out4 = 0; 66 } 67 } 68 69 /* permit base64 string ending with pad chars (ch == -3); not checking 70 * for one or two pad chars + optional whitespace reaches in_length) */ 71 /* permit base64 string truncated before in_length (in[i] == '\0') */ 72 switch (i == in_length || ch == -3 || in[i] != '\0' ? (i & 3) : 1) { 73 case 3: 74 result[out_pos++] = (out4 >> 10); 75 out4 <<= 2; 76 __attribute_fallthrough__ 77 case 2: 78 result[out_pos++] = (out4 >> 4) & 0xFF; 79 __attribute_fallthrough__ 80 case 0: 81 force_assert(out_pos <= out_length); 82 return out_pos; 83 case 1: /* pad char or str end can only come after 2+ base64 chars */ 84 default: 85 return 0; /* invalid character, abort */ 86 } 87 } 88 89 size_t li_base64_enc(char * const restrict out, const size_t out_length, const unsigned char * const restrict in, const size_t in_length, const base64_charset charset, const int pad) { 90 size_t i; 91 size_t out_pos = 0; 92 uint_fast32_t v; 93 const char* const base64_table = (charset) 94 ? base64_url_table /* BASE64_URL */ 95 : base64_standard_table; /* BASE64_STANDARD */ 96 const char padchar = base64_table[64]; /* padding char */ 97 98 /* check overflows */ 99 /* 1073741823 is max num full_tuples to avoid overflow in uint32_t; 100 * and (1 GB - 1) is ridiculously large for base64-encoded data */ 101 force_assert(in_length <= 3221225469); /* (3221225469+2) / 3 * 4 < UINT32_MAX */ 102 force_assert((in_length+2)/3*4 <= out_length); 103 104 for (i = 2; i < in_length; i += 3) { 105 v = (in[i-2] << 16) | (in[i-1] << 8) | in[i]; 106 out[out_pos+0] = base64_table[(v >> 18) & 0x3f]; 107 out[out_pos+1] = base64_table[(v >> 12) & 0x3f]; 108 out[out_pos+2] = base64_table[(v >> 6) & 0x3f]; 109 out[out_pos+3] = base64_table[(v ) & 0x3f]; 110 out_pos += 4; 111 } 112 113 switch (in_length - (i-2)) { 114 case 0: 115 default: 116 break; 117 case 1: 118 { 119 /* pretend in[i-1] = in[i] = 0, don't write last two (out_pos+3, out_pos+2) characters */ 120 v = (in[i-2] << 4); 121 out[out_pos+0] = base64_table[(v >> 6) & 0x3f]; 122 out[out_pos+1] = base64_table[(v ) & 0x3f]; 123 if (pad) { 124 out[out_pos+2] = out[out_pos+3] = padchar; 125 out_pos += 4; 126 } 127 else 128 out_pos += 2; 129 } 130 break; 131 case 2: 132 { 133 /* pretend in[i] = 0, don't write last (out_pos+3) character */ 134 v = (in[i-2] << 10) | (in[i-1] << 2); 135 out[out_pos+0] = base64_table[(v >> 12) & 0x3f]; 136 out[out_pos+1] = base64_table[(v >> 6) & 0x3f]; 137 out[out_pos+2] = base64_table[(v ) & 0x3f]; 138 if (pad) { 139 out[out_pos+3] = padchar; 140 out_pos += 4; 141 } 142 else 143 out_pos += 3; 144 } 145 break; 146 } 147 148 return out_pos; 149 } 150 151 152 char* buffer_append_base64_enc(buffer *out, const unsigned char* in, size_t in_length, base64_charset charset, int pad) { 153 const size_t reserve = (in_length+2)/3*4; 154 char * const result = buffer_string_prepare_append(out, reserve); 155 const size_t out_pos = 156 li_base64_enc(result, reserve, in, in_length, charset, pad); 157 158 buffer_commit(out, out_pos); 159 160 return result; 161 } 162 163 164 unsigned char* buffer_append_base64_decode(buffer *out, const char* in, size_t in_length, base64_charset charset) { 165 const size_t reserve = 3*(in_length/4) + 3; 166 unsigned char * const result = (unsigned char *) 167 buffer_string_prepare_append(out, reserve); 168 const size_t out_pos = 169 li_base64_dec(result, reserve, in, in_length, charset); 170 171 buffer_commit(out, out_pos); 172 173 return (out_pos || !in_length) ? result : NULL; 174 } 175