diff --git a/lib/base64-decode.c b/lib/base64-decode.c index b89db7ac..51db2679 100644 --- a/lib/base64-decode.c +++ b/lib/base64-decode.c @@ -91,3 +91,99 @@ lws_b64_encode_string(const char *in, int in_len, char *out, int out_size) return done; } + +/* + * returns length of decoded string in out, or -1 if out was too small + * according to out_size + */ + +LWS_VISIBLE int +lws_b64_decode_string(const char *in, char *out, int out_size) +{ + int len; + int i; + int done = 0; + unsigned char v; + unsigned char quad[4]; + + while (*in) { + + len = 0; + for (i = 0; i < 4 && *in; i++) { + + v = 0; + while (*in && !v) { + + v = *in++; + v = (v < 43 || v > 122) ? 0 : decode[v - 43]; + if (v) + v = (v == '$') ? 0 : v - 61; + if (*in) { + len++; + if (v) + quad[i] = v - 1; + } else + quad[i] = 0; + } + } + if (!len) + continue; + + if (out_size < (done + len - 1)) + /* out buffer is too small */ + return -1; + + if (len >= 2) + *out++ = quad[0] << 2 | quad[1] >> 4; + if (len >= 3) + *out++ = quad[1] << 4 | quad[2] >> 2; + if (len >= 4) + *out++ = ((quad[2] << 6) & 0xc0) | quad[3]; + + done += len - 1; + } + + if (done + 1 >= out_size) + return -1; + + *out++ = '\0'; + + return done; +} + +int +lws_b64_selftest(void) +{ + char buf[64]; + int n; + int test; + static const char * const plaintext[] = { + "sanity check base 64" + }; + static const char * const coded[] = { + "c2FuaXR5IGNoZWNrIGJhc2UgNjQ=" + }; + + for (test = 0; test < sizeof plaintext / sizeof(plaintext[0]); test++) { + + buf[sizeof(buf) - 1] = '\0'; + n = lws_b64_encode_string(plaintext[test], + strlen(plaintext[test]), buf, sizeof buf); + if (n != strlen(coded[test]) || strcmp(buf, coded[test])) { + lwsl_err("Failed lws_b64 encode selftest " + "%d result '%s' %d\n", test, buf, n); + return -1; + } + + buf[sizeof(buf) - 1] = '\0'; + n = lws_b64_decode_string(coded[test], buf, sizeof buf); + if (n != strlen(plaintext[test]) || + strcmp(buf, plaintext[test])) { + lwsl_err("Failed lws_b64 decode selftest " + "%d result '%s' %d\n", test, buf, n); + return -1; + } + } + + return 0; +}