commit 92602345e001d8e66038d5d98cbb21eea5ef40c9 Author: Nick Mathewson nickm@torproject.org Date: Fri Sep 16 17:48:20 2011 -0400
Function to detect certificate types that signal v3 certificates --- src/common/tortls.c | 71 +++++++++++++++++++++++++++++++++++++++++++++++++++ src/common/tortls.h | 1 + 2 files changed, 72 insertions(+), 0 deletions(-)
diff --git a/src/common/tortls.c b/src/common/tortls.c index 1435223..332d784 100644 --- a/src/common/tortls.c +++ b/src/common/tortls.c @@ -2075,6 +2075,77 @@ tor_tls_used_v1_handshake(tor_tls_t *tls) return 1; }
+/** Return true iff <b>name</b> is a DN of a kind that could only + * occur in a v3-handshake-indicating certificate */ +static int +dn_indicates_v3_cert(X509_NAME *name) +{ + X509_NAME_ENTRY *entry; + int n_entries; + ASN1_OBJECT *obj; + ASN1_STRING *str; + unsigned char *s; + int len, r; + + n_entries = X509_NAME_entry_count(name); + if (n_entries != 1) + return 1; /* More than one entry in the DN. */ + entry = X509_NAME_get_entry(name, 0); + + obj = X509_NAME_ENTRY_get_object(entry); + if (OBJ_obj2nid(obj) != OBJ_txt2nid("commonName")) + return 1; /* The entry isn't a commonName. */ + + str = X509_NAME_ENTRY_get_data(entry); + len = ASN1_STRING_to_UTF8(&s, str); + if (len < 0) + return 0; + r = fast_memneq(s + len - 4, ".net", 4); + OPENSSL_free(s); + return r; +} + +/** Return true iff the peer certificate we're received on <b>tls</b> + * indicates that this connection should use the v3 (in-protocol) + * authentication handshake. + * + * Only the connection initiator should use this, and only once the initial + * handshake is done; the responder detects a v1 handshake by cipher types, + * and a v3/v2 handshake by Versions cell vs renegotiation. + */ +int +tor_tls_received_v3_certificate(tor_tls_t *tls) +{ + X509 *cert = SSL_get_peer_certificate(tls->ssl); + EVP_PKEY *key; + X509_NAME *issuer_name, *subject_name; + + if (!cert) { + log_warn(LD_BUG, "Called on a connection with no peer certificate"); + return 0; + } + + subject_name = X509_get_subject_name(cert); + issuer_name = X509_get_issuer_name(cert); + + if (X509_name_cmp(subject_name, issuer_name) == 0) + return 1; /* purportedly self signed */ + + if (dn_indicates_v3_cert(subject_name) || + dn_indicates_v3_cert(issuer_name)) + return 1; /* DN is fancy */ + + key = X509_get_pubkey(cert); + if (EVP_PKEY_bits(key) != 1024 || + EVP_PKEY_type(key->type) != EVP_PKEY_RSA) { + EVP_PKEY_free(key); + return 1; /* Key is fancy */ + } + + EVP_PKEY_free(key); + return 0; +} + /** Return the number of server handshakes that we've noticed doing on * <b>tls</b>. */ int diff --git a/src/common/tortls.h b/src/common/tortls.h index 40eb830..70d24a5 100644 --- a/src/common/tortls.h +++ b/src/common/tortls.h @@ -88,6 +88,7 @@ void tor_tls_get_buffer_sizes(tor_tls_t *tls, size_t *wbuf_capacity, size_t *wbuf_bytes);
int tor_tls_used_v1_handshake(tor_tls_t *tls); +int tor_tls_received_v3_certificate(tor_tls_t *tls); int tor_tls_get_num_server_handshakes(tor_tls_t *tls); int tor_tls_server_got_renegotiate(tor_tls_t *tls); int tor_tls_get_tlssecrets(tor_tls_t *tls, uint8_t *secrets_out);