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PPP, magic: cleanup code and documentation

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Documentation and simple code cleanup, no behavior change.
This commit is contained in:
Sylvain Rochet 2020-10-27 21:40:56 +01:00
parent 72d9132ecf
commit e239222775
1 changed files with 22 additions and 30 deletions
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52
src/netif/ppp/magic.c
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@ -114,12 +114,12 @@ static void magic_churnrand(char *rand_data, u32_t rand_len) {
u32_t rand;
#endif /* LWIP_RAND */
} sys_data;
/* Load sys_data fields here. */
magic_randomseed += sys_jiffies();
sys_data.jiffies = magic_randomseed;
#ifdef LWIP_RAND
sys_data.rand = LWIP_RAND();
#endif /* LWIP_RAND */
/* Load sys_data fields here. */
lwip_md5_update(&md5_ctx, (u_char *)&sys_data, sizeof(sys_data));
}
lwip_md5_finish(&md5_ctx, (u_char *)magic_randpool);
@ -142,7 +142,7 @@ void magic_randomize(void) {
}
/*
* magic_random_bytes - Fill a buffer with random bytes.
* Fill a buffer with random bytes.
*
* Use the random pool to generate random data. This degrades to pseudo
* random when used faster than randomness is supplied using magic_churnrand().
@ -180,56 +180,45 @@ void magic_random_bytes(unsigned char *buf, u32_t buf_len) {
}
/*
* Return a new random number.
* Return a new 32-bit random number.
*/
u32_t magic(void) {
u32_t new_rand;
magic_random_bytes((unsigned char *)&new_rand, sizeof(new_rand));
return new_rand;
}
#else /* PPP_MD5_RANDM */
/*****************************/
/*** LOCAL DATA STRUCTURES ***/
/*****************************/
#ifndef LWIP_RAND
static int magic_randomized; /* Set when truly randomized. */
#endif /* LWIP_RAND */
static u32_t magic_randomseed; /* Seed used for random number generation. */
/***********************************/
/*** PUBLIC FUNCTION DEFINITIONS ***/
/***********************************/
/*
* Initialize the random number generator.
*
* Here we attempt to compute a random number seed but even if
* it isn't random, we'll randomize it later.
*
* The current method uses the fields from the real time clock,
* the idle process counter, the millisecond counter, and the
* hardware timer tick counter. When this is invoked
* in startup(), then the idle counter and timer values may
* repeat after each boot and the real time clock may not be
* operational. Thus we call it again on the first random
* event.
* The current method uses the jiffies counter. When this is
* invoked at startup the jiffies counter value may repeat
* after each boot. Thus we call it again on the first
* random event.
*
* If LWIP_RAND if available, we do not call srand() as we are
* not going to call rand().
*/
void magic_init(void) {
magic_randomseed += sys_jiffies();
#ifndef LWIP_RAND
/* Initialize the Borland random number generator. */
/* Initialize the random number generator. */
srand((unsigned)magic_randomseed);
#endif /* LWIP_RAND */
}
/*
* magic_init - Initialize the magic number generator.
*
* Randomize our random seed value. Here we use the fact that
* this function is called at *truly random* times by the polling
* and network functions. Here we only get 16 bits of new random
@ -242,23 +231,26 @@ void magic_randomize(void) {
magic_randomized = !0;
magic_init();
/* The initialization function also updates the seed. */
} else {
#endif /* LWIP_RAND */
magic_randomseed += sys_jiffies();
#ifndef LWIP_RAND
return;
}
#endif /* LWIP_RAND */
magic_randomseed += sys_jiffies();
}
/*
* Return a new random number.
* Return a new 32-bit random number.
*
* Here we use the Borland rand() function to supply a pseudo random
* Here we use the rand() function to supply a pseudo random
* number which we make truly random by combining it with our own
* seed which is randomized by truly random events.
* Thus the numbers will be truly random unless there have been no
* operator or network events in which case it will be pseudo random
* seeded by the real time clock.
* seeded by srand().
*
* Alternatively, use LWIP_RAND if available, but we do not assume
* it is returning 32 bits of random data because it is probably
* going to be defined to directly return the rand() value. For
* example, LCP magic numbers are 32-bit random values.
*/
u32_t magic(void) {
#ifdef LWIP_RAND
@ -269,7 +261,7 @@ u32_t magic(void) {
}
/*
* magic_random_bytes - Fill a buffer with random bytes.
* Fill a buffer with random bytes.
*/
void magic_random_bytes(unsigned char *buf, u32_t buf_len) {
u32_t new_rand, n;