227 lines
8.4 KiB
C
227 lines
8.4 KiB
C
/*
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* Utility routines. This file is part of Shairport.
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* Copyright (c) James Laird 2013
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* The volume to attenuation function vol2attn copyright (c) Mike Brady 2014
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* All rights reserved.
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*
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* Permission is hereby granted, free of charge, to any person
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* obtaining a copy of this software and associated documentation
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* files (the "Software"), to deal in the Software without
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* restriction, including without limitation the rights to use,
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* copy, modify, merge, publish, distribute, sublicense, and/or
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* sell copies of the Software, and to permit persons to whom the
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* Software is furnished to do so, subject to the following conditions:
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*
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* The above copyright notice and this permission notice shall be
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* included in all copies or substantial portions of the Software.
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*
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* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
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* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
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* OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
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* NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
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* HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
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* WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
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* FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
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* OTHER DEALINGS IN THE SOFTWARE.
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*/
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#include <stdio.h>
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#include <stdarg.h>
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#include <stdlib.h>
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#include <memory.h>
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#include <openssl/rsa.h>
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#include <openssl/pem.h>
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#include <openssl/evp.h>
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#include <openssl/bio.h>
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#include <openssl/buffer.h>
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#include "common.h"
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#include <libdaemon/dlog.h>
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shairport_cfg config;
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int debuglev = 0;
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void die(char *format, ...) {
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char s[1024];
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s[0]=0;
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va_list args;
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va_start(args, format);
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vsprintf(s,format,args);
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va_end(args);
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daemon_log(LOG_EMERG,"%s", s);
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shairport_shutdown();
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exit(1);
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}
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void warn(char *format, ...) {
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char s[1024];
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s[0]=0;
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va_list args;
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va_start(args, format);
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vsprintf(s,format,args);
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va_end(args);
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daemon_log(LOG_WARNING,"%s", s);
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}
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void debug(int level, char *format, ...) {
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if (level > debuglev)
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return;
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char s[1024];
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s[0]=0;
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va_list args;
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va_start(args, format);
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vsprintf(s,format,args);
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va_end(args);
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daemon_log(LOG_DEBUG,"%s", s);
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}
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char *base64_enc(uint8_t *input, int length) {
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BIO *bmem, *b64;
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BUF_MEM *bptr;
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b64 = BIO_new(BIO_f_base64());
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bmem = BIO_new(BIO_s_mem());
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b64 = BIO_push(b64, bmem);
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BIO_set_flags(b64, BIO_FLAGS_BASE64_NO_NL);
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BIO_write(b64, input, length);
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BIO_flush(b64);
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BIO_get_mem_ptr(b64, &bptr);
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char *buf = (char *)malloc(bptr->length);
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if (bptr->length) {
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memcpy(buf, bptr->data, bptr->length-1);
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buf[bptr->length-1] = 0;
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}
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BIO_free_all(bmem);
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return buf;
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}
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uint8_t *base64_dec(char *input, int *outlen) {
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BIO *bmem, *b64;
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int inlen = strlen(input);
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b64 = BIO_new(BIO_f_base64());
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BIO_set_flags(b64, BIO_FLAGS_BASE64_NO_NL);
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bmem = BIO_new(BIO_s_mem());
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b64 = BIO_push(b64, bmem);
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// Apple cut the padding off their challenges; restore it
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BIO_write(bmem, input, inlen);
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while (inlen++ & 3)
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BIO_write(bmem, "=", 1);
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BIO_flush(bmem);
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int bufsize = strlen(input)*3/4 + 1;
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uint8_t *buf = malloc(bufsize);
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int nread;
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nread = BIO_read(b64, buf, bufsize);
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BIO_free_all(bmem);
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*outlen = nread;
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return buf;
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}
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static char super_secret_key[] =
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"-----BEGIN RSA PRIVATE KEY-----\n"
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"MIIEpQIBAAKCAQEA59dE8qLieItsH1WgjrcFRKj6eUWqi+bGLOX1HL3U3GhC/j0Qg90u3sG/1CUt\n"
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"wC5vOYvfDmFI6oSFXi5ELabWJmT2dKHzBJKa3k9ok+8t9ucRqMd6DZHJ2YCCLlDRKSKv6kDqnw4U\n"
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"wPdpOMXziC/AMj3Z/lUVX1G7WSHCAWKf1zNS1eLvqr+boEjXuBOitnZ/bDzPHrTOZz0Dew0uowxf\n"
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"/+sG+NCK3eQJVxqcaJ/vEHKIVd2M+5qL71yJQ+87X6oV3eaYvt3zWZYD6z5vYTcrtij2VZ9Zmni/\n"
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"UAaHqn9JdsBWLUEpVviYnhimNVvYFZeCXg/IdTQ+x4IRdiXNv5hEewIDAQABAoIBAQDl8Axy9XfW\n"
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"BLmkzkEiqoSwF0PsmVrPzH9KsnwLGH+QZlvjWd8SWYGN7u1507HvhF5N3drJoVU3O14nDY4TFQAa\n"
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"LlJ9VM35AApXaLyY1ERrN7u9ALKd2LUwYhM7Km539O4yUFYikE2nIPscEsA5ltpxOgUGCY7b7ez5\n"
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"NtD6nL1ZKauw7aNXmVAvmJTcuPxWmoktF3gDJKK2wxZuNGcJE0uFQEG4Z3BrWP7yoNuSK3dii2jm\n"
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"lpPHr0O/KnPQtzI3eguhe0TwUem/eYSdyzMyVx/YpwkzwtYL3sR5k0o9rKQLtvLzfAqdBxBurciz\n"
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"aaA/L0HIgAmOit1GJA2saMxTVPNhAoGBAPfgv1oeZxgxmotiCcMXFEQEWflzhWYTsXrhUIuz5jFu\n"
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"a39GLS99ZEErhLdrwj8rDDViRVJ5skOp9zFvlYAHs0xh92ji1E7V/ysnKBfsMrPkk5KSKPrnjndM\n"
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"oPdevWnVkgJ5jxFuNgxkOLMuG9i53B4yMvDTCRiIPMQ++N2iLDaRAoGBAO9v//mU8eVkQaoANf0Z\n"
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"oMjW8CN4xwWA2cSEIHkd9AfFkftuv8oyLDCG3ZAf0vrhrrtkrfa7ef+AUb69DNggq4mHQAYBp7L+\n"
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"k5DKzJrKuO0r+R0YbY9pZD1+/g9dVt91d6LQNepUE/yY2PP5CNoFmjedpLHMOPFdVgqDzDFxU8hL\n"
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"AoGBANDrr7xAJbqBjHVwIzQ4To9pb4BNeqDndk5Qe7fT3+/H1njGaC0/rXE0Qb7q5ySgnsCb3DvA\n"
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"cJyRM9SJ7OKlGt0FMSdJD5KG0XPIpAVNwgpXXH5MDJg09KHeh0kXo+QA6viFBi21y340NonnEfdf\n"
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"54PX4ZGS/Xac1UK+pLkBB+zRAoGAf0AY3H3qKS2lMEI4bzEFoHeK3G895pDaK3TFBVmD7fV0Zhov\n"
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"17fegFPMwOII8MisYm9ZfT2Z0s5Ro3s5rkt+nvLAdfC/PYPKzTLalpGSwomSNYJcB9HNMlmhkGzc\n"
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"1JnLYT4iyUyx6pcZBmCd8bD0iwY/FzcgNDaUmbX9+XDvRA0CgYEAkE7pIPlE71qvfJQgoA9em0gI\n"
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"LAuE4Pu13aKiJnfft7hIjbK+5kyb3TysZvoyDnb3HOKvInK7vXbKuU4ISgxB2bB3HcYzQMGsz1qJ\n"
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"2gG0N5hvJpzwwhbhXqFKA4zaaSrw622wDniAK5MlIE0tIAKKP4yxNGjoD2QYjhBGuhvkWKY=\n"
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"-----END RSA PRIVATE KEY-----";
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uint8_t *rsa_apply(uint8_t *input, int inlen, int *outlen, int mode) {
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static RSA *rsa = NULL;
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if (!rsa) {
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BIO *bmem = BIO_new_mem_buf(super_secret_key, -1);
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rsa = PEM_read_bio_RSAPrivateKey(bmem, NULL, NULL, NULL);
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BIO_free(bmem);
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}
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uint8_t *out = malloc(RSA_size(rsa));
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switch (mode) {
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case RSA_MODE_AUTH:
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*outlen = RSA_private_encrypt(inlen, input, out, rsa,
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RSA_PKCS1_PADDING);
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break;
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case RSA_MODE_KEY:
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*outlen = RSA_private_decrypt(inlen, input, out, rsa,
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RSA_PKCS1_OAEP_PADDING);
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break;
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default:
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die("bad rsa mode");
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}
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return out;
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}
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// Given a volume (0 to -30) and high and low attenuations available in the mixer in dB, return an attenuation depending on the volume and the function's transfer function
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// See http://tangentsoft.net/audio/atten.html for data on good attenuators.
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// We want a smooth attenuation function, like, for example, the ALPS RK27 Potentiometer transfer functions referred to at the link above.
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double vol2attn(double vol, long max_db, long min_db) {
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// We use a little coordinate geometry to build a transfer function from the volume passed in to the device's dynamic range.
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// (See the diagram in the documents folder.)
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// The x axis is the "volume in" which will be from -30 to 0. The y axis will be the "volume out" which will be from the bottom of the range to the top.
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// We build the transfer function from one or more lines. We characterise each line with two numbers:
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// the first is where on x the line starts when y=0 (x can be fromfrom 0 to -30); the second is where on y the line stops when when x is -30.
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// thus, if the line was characterised as {0,-30}, it would be an identity transfer.
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// Assuming, for example, a dynamic range of lv=-60 to hv=0
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// Typically we'll use three lines -- a three order transfer function
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// First: {0,25} giving a gentle slope
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// Second: {-12,-25-(lv+25)/2} giving a faster slope from y=0 at x=-12 to y=-42.5 at x=-30
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// Third: {-19,lv} giving a fast slope from y=0 at x=-19 to y=-60 at x=-30
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#define order 3
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double vol_setting = max_db;
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if ((vol<=0.0) && (vol>=-30.0)) {
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long range_db = max_db-min_db; // this will be a positive nunmber
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// debug(1,"Volume min %ddB, max %ddB, range %ddB.",min_db,max_db,range_db);
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double first_slope = -2500.0; // this is the slope of the attenuation at the high end -- 25dB for the full rotation.
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if (-range_db>first_slope)
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first_slope = range_db;
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double lines[order][2] = {{0,first_slope},{-12,first_slope-(range_db+first_slope)/2},{-19,-range_db}};
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int i;
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for (i=0;i<order;i++) {
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if (vol<=lines[i][0]) {
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double tvol = lines[i][1]*(vol-lines[i][0])/(-30-lines[i][0]);
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// debug(1,"On line %d, end point of %f, input vol %f yields output vol %f.",i,lines[i][1],vol,tvol);
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if (tvol<vol_setting)
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vol_setting=tvol;
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}
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}
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vol_setting+=max_db;
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} else if (vol!=-144.0) {
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debug(1,"Volume request value %f is out of range: should be from 0.0 to -30.0 or -144.0.",vol);
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} else {
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vol_setting = min_db; // for safety, return the lowest setting...
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}
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// debug(1,"returning an attenuation of %f.",vol_setting);
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return vol_setting;
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}
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