Commit 200c39b6 authored by Nick Mathewson's avatar Nick Mathewson 🌉
Browse files

Document the microdescriptor code better.

parent d61b5df9
......@@ -1481,7 +1481,8 @@ crypto_digest_algorithm_get_name(digest_algorithm_t alg)
}
}
/** DOCDOC */
/** Given the name of a digest algorithm, return its integer value, or -1 if
* the name is not recognized. */
int
crypto_digest_algorithm_parse_name(const char *name)
{
......
......@@ -1885,7 +1885,8 @@ version_from_platform(const char *platform)
* The format argument has three possible values:
* NS_V2 - Output an entry suitable for a V2 NS opinion document
* NS_V3_CONSENSUS - Output the first portion of a V3 NS consensus entry
* NS_V3_CONSENSUS_MICRODESC - DOCDOC
* NS_V3_CONSENSUS_MICRODESC - Output the first portion of a V3 microdesc
* consensus entry.
* NS_V3_VOTE - Output a complete V3 NS vote
* NS_CONTROL_PORT - Output a NS document for the control port
*/
......
......@@ -11,7 +11,9 @@
* \brief Functions to compute directory consensus, and schedule voting.
**/
/** DOCDOC*/
/** A consensus that we have built and are appending signatures to. Once it's
* time to publish it, it will become an active consensus if it accumulates
* enough signatures. */
typedef struct pending_consensus_t {
/** The body of the consensus that we're currently building. Once we
* have it built, it goes into dirserv.c */
......@@ -264,7 +266,8 @@ get_voter(const networkstatus_t *vote)
return smartlist_get(vote->voters, 0);
}
/** DOCDOC */
/** Return the signature made by <b>voter</b> using the algorithm
* <b>alg</b>, or NULL if none is found. */
document_signature_t *
voter_get_sig_by_algorithm(const networkstatus_voter_info_t *voter,
digest_algorithm_t alg)
......@@ -425,7 +428,8 @@ compute_routerstatus_consensus(smartlist_t *votes, int consensus_method,
char d[DIGEST256_LEN];
if (compare_vote_rs(rs, most))
continue;
if (!vote_routerstatus_find_microdesc_hash(d, rs, consensus_method))
if (!vote_routerstatus_find_microdesc_hash(d, rs, consensus_method,
DIGEST_SHA256))
smartlist_add(digests, tor_memdup(d, sizeof(d)));
} SMARTLIST_FOREACH_END(rs);
smartlist_sort_digests256(digests);
......@@ -439,9 +443,9 @@ compute_routerstatus_consensus(smartlist_t *votes, int consensus_method,
return most;
}
/** Given a list of strings in <b>lst</b>, set the DIGEST_LEN-byte digest at
* <b>digest_out</b> to the hash of the concatenation of those strings. DOCDOC
* new arguments. */
/** Given a list of strings in <b>lst</b>, set the <b>len_out</b>-byte digest
* at <b>digest_out</b> to the hash of the concatenation of those strings,
* computed with the algorithm <b>alg</b>. */
static void
hash_list_members(char *digest_out, size_t len_out,
smartlist_t *lst, digest_algorithm_t alg)
......@@ -1523,7 +1527,11 @@ networkstatus_add_detached_signatures(networkstatus_t *target,
return r;
}
/** DOCDOC */
/** Return a newly allocated string containing all the signatures on
* <b>consensus</b> by all voters. If <b>for_detached_signatures</b> is true,
* then the signatures will be put in a detached signatures document, so
* prefix any non-NS-flavored signatures with "additional-signature" rather
* than "directory-signature". */
static char *
networkstatus_format_signatures(networkstatus_t *consensus,
int for_detached_signatures)
......@@ -1674,7 +1682,9 @@ networkstatus_get_detached_signatures(smartlist_t *consensuses)
return result;
}
/** DOCDOC */
/** Return a newly allocated string holding a detached-signatures document for
* all of the in-progress consensuses in the <b>n_flavors</b>-element array at
* <b>pending</b>. */
static char *
get_detached_signatures_from_pending_consensuses(pending_consensus_t *pending,
int n_flavors)
......@@ -2049,7 +2059,8 @@ dirvote_fetch_missing_signatures(void)
0, NULL);
}
/** DOCDOC */
/** Release all storage held by pending consensuses (those waiting for
* signatures). */
static void
dirvote_clear_pending_consensuses(void)
{
......@@ -2775,7 +2786,10 @@ dirvote_create_microdescriptor(const routerinfo_t *ri)
/** Cached space-separated string to hold */
static char *microdesc_consensus_methods = NULL;
/** DOCDOC */
/** Format the appropriate vote line to describe the microdescriptor <b>md</b>
* in a consensus vote document. Write it into the <b>out_len</b>-byte buffer
* in <b>out</b>. Return -1 on failure and the number of characters written
* on success. */
int
dirvote_format_microdesc_vote_line(char *out, size_t out_len,
const microdesc_t *md)
......@@ -2798,19 +2812,25 @@ dirvote_format_microdesc_vote_line(char *out, size_t out_len,
return strlen(out);
}
/** DOCDOC */
/** If <b>vrs</b> has a hash made for the consensus method <b>method</b> with
* the digest algorithm <b>alg</b>, decode it and copy it into
* <b>digest256_out</b> and return 0. Otherwise return -1. */
int
vote_routerstatus_find_microdesc_hash(char *digest256_out,
const vote_routerstatus_t *vrs,
int method)
int method,
digest_algorithm_t alg)
{
/* XXXX only returns the sha256 method. */
const vote_microdesc_hash_t *h;
char mstr[64];
size_t mlen;
char dstr[64];
tor_snprintf(mstr, sizeof(mstr), "%d", method);
mlen = strlen(mstr);
tor_snprintf(dstr, sizeof(dstr), " %s=",
crypto_digest_algorithm_get_name(alg));
for (h = vrs->microdesc; h; h = h->next) {
const char *cp = h->microdesc_hash_line;
......@@ -2824,10 +2844,10 @@ vote_routerstatus_find_microdesc_hash(char *digest256_out,
char buf[BASE64_DIGEST256_LEN+1];
/* XXXX ignores extraneous stuff if the digest is too long. This
* seems harmless enough, right? */
cp = strstr(cp, " sha256=");
cp = strstr(cp, dstr);
if (!cp)
return -1;
cp += strlen(" sha256=");
cp += strlen(dstr);
strlcpy(buf, cp, sizeof(buf));
return digest256_from_base64(digest256_out, buf);
}
......
......@@ -3,20 +3,26 @@
#include "or.h"
/** DOCDOC everything here. */
#define MICRODESC_IN_CONSENSUS 1
#define MICRODESC_IN_VOTE 2
/** A data structure to hold a bunch of cached microdescriptors. There are
* two active files in the cache: a "cache file" that we mmap, and a "journal
* file" that we append to. Periodically, we rebuild the cache file to hold
* only the microdescriptors that we want to keep */
struct microdesc_cache_t {
/** Map from sha256-digest to microdesc_t for every microdesc_t in the
* cache. */
HT_HEAD(microdesc_map, microdesc_t) map;
/** Name of the cache file. */
char *cache_fname;
/** Name of the journal file. */
char *journal_fname;
/** Mmap'd contents of the cache file, or NULL if there is none. */
tor_mmap_t *cache_content;
/** Number of bytes used in the journal file. */
size_t journal_len;
};
/** Helper: computes a hash of <b>md</b> to place it in a hash table. */
static INLINE unsigned int
_microdesc_hash(microdesc_t *md)
{
......@@ -28,6 +34,7 @@ _microdesc_hash(microdesc_t *md)
#endif
}
/** Helper: compares <b>a</b> and </b> for equality for hash-table purposes. */
static INLINE int
_microdesc_eq(microdesc_t *a, microdesc_t *b)
{
......@@ -40,7 +47,10 @@ HT_GENERATE(microdesc_map, microdesc_t, node,
_microdesc_hash, _microdesc_eq, 0.6,
_tor_malloc, _tor_realloc, _tor_free);
/* returns n bytes written */
/** Write the body of <b>md</b> into <b>f</b>, with appropriate annotations.
* On success, return the total number of bytes written, and set
* *<b>annotation_len_out</b> to the number of bytes written as
* annotations. */
static int
dump_microdescriptor(FILE *f, microdesc_t *md, int *annotation_len_out)
{
......@@ -64,8 +74,11 @@ dump_microdescriptor(FILE *f, microdesc_t *md, int *annotation_len_out)
return r;
}
/** Holds a pointer to the current microdesc_cache_t object, or NULL if no
* such object has been allocated. */
static microdesc_cache_t *the_microdesc_cache = NULL;
/** Return a pointer to the microdescriptor cache, loading it if necessary. */
microdesc_cache_t *
get_microdesc_cache(void)
{
......@@ -86,7 +99,12 @@ get_microdesc_cache(void)
3) Downloaded.
*/
/* Returns list of added microdesc_t. */
/** Decode the microdescriptors from the string starting at <b>s</b> and
* ending at <b>eos</b>, and store them in <b>cache</b>. If <b>no-save</b>,
* mark them as non-writable to disk. If <b>where</b> is SAVED_IN_CACHE,
* leave their bodies as pointers to the mmap'd cache. If where is
* <b>SAVED_NOWHERE</b>, do not allow annotations. Return a list of the added
* microdescriptors. */
smartlist_t *
microdescs_add_to_cache(microdesc_cache_t *cache,
const char *s, const char *eos, saved_location_t where,
......@@ -107,8 +125,9 @@ microdescs_add_to_cache(microdesc_cache_t *cache,
return added;
}
/* Returns list of added microdesc_t. Frees any not added. Updates last_listed.
*/
/* As microdescs_add_to_cache, but takes a list of micrdescriptors instead of
* a string to encode. Frees any members of <b>descriptors</b> that it does
* not add. */
smartlist_t *
microdescs_add_list_to_cache(microdesc_cache_t *cache,
smartlist_t *descriptors, saved_location_t where,
......@@ -174,6 +193,7 @@ microdescs_add_list_to_cache(microdesc_cache_t *cache,
return added;
}
/** Remove every microdescriptor in <b>cache</b>. */
void
microdesc_cache_clear(microdesc_cache_t *cache)
{
......@@ -190,6 +210,8 @@ microdesc_cache_clear(microdesc_cache_t *cache)
}
}
/** Reload the contents of <b>cache</b> from disk. If it is empty, load it
* for the first time. Return 0 on success, -1 on failure. */
int
microdesc_cache_reload(microdesc_cache_t *cache)
{
......@@ -228,6 +250,9 @@ microdesc_cache_reload(microdesc_cache_t *cache)
return 0;
}
/** Regenerate the main cache file for <b>cache</b>, clear the journal file,
* and update every microdesc_t in the cache with pointers to its new
* location. */
int
microdesc_cache_rebuild(microdesc_cache_t *cache)
{
......@@ -298,6 +323,8 @@ microdesc_cache_rebuild(microdesc_cache_t *cache)
return 0;
}
/** Deallocate a single microdescriptor. Note: the microdescriptor MUST have
* previously been removed from the cache if it had ever been inserted. */
void
microdesc_free(microdesc_t *md)
{
......@@ -316,6 +343,7 @@ microdesc_free(microdesc_t *md)
tor_free(md);
}
/** Free all storage held in the microdesc.c module. */
void
microdesc_free_all(void)
{
......
......@@ -2082,7 +2082,8 @@ networkstatus_get_flavor_name(consensus_flavor_t flav)
}
}
/** DOCDOC return -1 on unknown */
/** Return the consensus_flavor_t value for the flavor called <b>flavname</b>,
* or -1 if the flavor is not recongized. */
int
networkstatus_parse_flavor_name(const char *flavname)
{
......
......@@ -1559,27 +1559,48 @@ typedef struct routerstatus_t {
} routerstatus_t;
/**DOCDOC*/
/** A microdescriptor is the smallest amount of information needed to build a
* circuit through a router. They are generated by the directory authorities,
* using information from the uploaded routerinfo documents. They are not
* self-signed, but are rather authenticated by having their hash in a signed
* networkstatus document. */
typedef struct microdesc_t {
/** Hashtable node, used to look up the microdesc by its digest. */
HT_ENTRY(microdesc_t) node;
/* Cache information */
/** When was this microdescriptor last listed in a consensus document?
* Once a microdesc has been unlisted long enough, we can drop it.
*/
time_t last_listed;
/** Where is this microdescriptor currently stored? */
saved_location_t saved_location : 3;
/** If true, do not attempt to cache this microdescriptor on disk. */
unsigned int no_save : 1;
/** If saved_location == SAVED_IN_CACHE, this field holds the offset of the
* microdescriptor in the cache. */
off_t off;
/* The string containing the microdesc. */
/** A pointer to the encoded body of the microdescriptor. If the
* saved_location is SAVED_IN_CACHE, then the body is a pointer into an
* mmap'd region. Otherwise, it is a malloc'd string. The string might not
* be NUL-terminated; take the length from <b>bodylen</b>. */
char *body;
/** The length of the microdescriptor in <b>body</b>. */
size_t bodylen;
/** A SHA256-digest of the microdescriptor. */
char digest[DIGEST256_LEN];
/* Fields in the microdescriptor. */
/** As routerinfo_t.onion_pkey */
crypto_pk_env_t *onion_pkey;
/** As routerinfo_t.family */
smartlist_t *family;
/** Encoded exit policy summary */
char *exitsummary; /**< exit policy summary -
* XXX this probably should not stay a string. */
} microdesc_t;
......@@ -1687,16 +1708,18 @@ typedef enum {
NS_TYPE_OPINION,
} networkstatus_type_t;
/** DOCDOC */
/** Enumerates recognized flavors of a consensus networkstatus document. All
* flavors of a consensus are generated from the same set of votes, but they
* present different types information to different versions of Tor. */
typedef enum {
FLAV_NS = 0,
FLAV_MICRODESC = 1,
} consensus_flavor_t;
/** DOCDOC */
/** Which consensus flavor do we actually want to use to build circuits? */
#define USABLE_CONSENSUS_FLAVOR FLAV_NS
/** DOCDOC */
/** How many different consensus flavors are there? */
#define N_CONSENSUS_FLAVORS ((int)(FLAV_MICRODESC)+1)
/** A common structure to hold a v3 network status vote, or a v3 network
......@@ -3892,7 +3915,8 @@ int dirvote_format_microdesc_vote_line(char *out, size_t out_len,
const microdesc_t *md);
int vote_routerstatus_find_microdesc_hash(char *digest256_out,
const vote_routerstatus_t *vrs,
int method);
int method,
digest_algorithm_t alg);
document_signature_t *voter_get_sig_by_algorithm(
const networkstatus_voter_info_t *voter,
digest_algorithm_t alg);
......
......@@ -640,7 +640,8 @@ router_get_networkstatus_v2_hash(const char *s, char *digest)
DIGEST_SHA1);
}
/** DOCDOC */
/** Set <b>digests</b> to all the digests of the consensus document in
* <b>s</b> */
int
router_get_networkstatus_v3_hashes(const char *s, digests_t *digests)
{
......@@ -677,8 +678,6 @@ router_get_extrainfo_hash(const char *s, char *digest)
* surround it with -----BEGIN/END----- pairs, and write it to the
* <b>buf_len</b>-byte buffer at <b>buf</b>. Return 0 on success, -1 on
* failure.
*
* DOCDOC alg
*/
int
router_append_dirobj_signature(char *buf, size_t buf_len, const char *digest,
......@@ -1901,7 +1900,7 @@ find_start_of_next_routerstatus(const char *s)
* consensus, and we should parse it according to the method used to
* make that consensus.
*
* DOCDOC flav
* Parse according to the syntax used by the consensus flavor <b>flav</b>.
**/
static routerstatus_t *
routerstatus_parse_entry_from_string(memarea_t *area,
......@@ -2832,7 +2831,9 @@ networkstatus_parse_vote_from_string(const char *s, const char **eos_out,
return ns;
}
/** DOCDOC */
/** Return the digests_t that holds the digests of the
* <b>flavor_name</b>-flavored networkstatus according to the detached
* signatures document <b>sigs</b>, allocating a new digests_t as neeeded. */
static digests_t *
detached_get_digests(ns_detached_signatures_t *sigs, const char *flavor_name)
{
......@@ -2844,7 +2845,9 @@ detached_get_digests(ns_detached_signatures_t *sigs, const char *flavor_name)
return d;
}
/** DOCDOC */
/** Return the list of signatures of the <b>flavor_name</b>-flavored
* networkstatus according to the detached signatures document <b>sigs</b>,
* allocating a new digests_t as neeeded. */
static smartlist_t *
detached_get_signatures(ns_detached_signatures_t *sigs,
const char *flavor_name)
......@@ -3719,8 +3722,8 @@ router_get_hashes_impl(const char *s, digests_t *digests,
return 0;
}
/** DOCDOC Assuming that s starts with a microdesc, return the start of the
* *NEXT* one. */
/** Assuming that s starts with a microdesc, return the start of the
* *NEXT* one. Return NULL on "not found." */
static const char *
find_start_of_next_microdesc(const char *s, const char *eos)
{
......@@ -3771,7 +3774,11 @@ find_start_of_next_microdesc(const char *s, const char *eos)
#undef NEXT_LINE
}
/**DOCDOC*/
/** Parse as many microdescriptors as are found from the string starting at
* <b>s</b> and ending at <b>eos</b>. If allow_annotations is set, read any
* annotations we recognize and ignore ones we don't. If <b>copy_body</b> is
* true, then strdup the bodies of the microdescriptors. Return all newly
* parsed microdescriptors in a newly allocated smartlist_t. */
smartlist_t *
microdescs_parse_from_string(const char *s, const char *eos,
int allow_annotations, int copy_body)
......
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