Add initial interfaces and code for TLS support. Interfaces are right; code needs work and testing.

svn:r424

1 files changed, 323 insertions, 0 deletions

diff --git a/src/common/tortls.c b/src/common/tortls.c
new file mode 100644
index 0000000000..9e964de6e6
--- /dev/null
+++ b/src/common/tortls.c
@@ -0,0 +1,323 @@
+/* Copyright 2003 Roger Dingledine. */
+/* See LICENSE for licensing information */
+/* $Id$ */
+
+/* TLS wrappers for The Onion Router.  (Unlike other tor functions, these
+ * are prefixed with tor_ in order to avoid conflicting with OpenSSL
+ * functions and variables.)
+ */
+
+#include "./crypto.h"
+#include "./tortls.h"
+#include "./util.h"
+
+#include <assert.h>
+#include <openssl/ssl.h>
+#include <openssl/err.h>
+#include <openssl/tls1.h>
+#include <openssl/asn1.h>
+#include <openssl/bio.h>
+
+struct tor_tls_context_st {
+  SSL_CTX *ctx;
+};
+
+struct tor_tls_st {
+  SSL *ssl;
+  int socket;
+  enum { 
+    TOR_TLS_ST_HANDSHAKE, TOR_TLS_ST_OPEN, TOR_TLS_ST_GOTCLOSE, 
+    TOR_TLS_ST_SENTCLOSE, TOR_TLS_ST_CLOSED
+  } state;
+  int isServer;
+};
+
+#define _TOR_TLS_SYSCALL    -6
+#define _TOR_TLS_ZERORETURN -5
+
+static int
+tor_tls_get_error(tor_tls *tls, int r, int extra)
+{
+  int err = SSL_get_error(tls->ssl, r);
+  switch (err) {
+    case SSL_ERROR_NONE:
+      return TOR_TLS_DONE;
+    case SSL_ERROR_WANT_READ:
+      return TOR_TLS_WANTREAD;
+    case SSL_ERROR_WANT_WRITE:
+      return TOR_TLS_WANTWRITE;
+    case SSL_ERROR_SYSCALL:
+      return extra ? _TOR_TLS_SYSCALL : TOR_TLS_ERROR;
+    case SSL_ERROR_ZERO_RETURN:
+      return extra ? _TOR_TLS_ZERORETURN : TOR_TLS_ERROR;
+    default:
+      return TOR_TLS_ERROR;
+  }
+}
+
+static int always_accept_verify_cb(int preverify_ok, 
+                                   X509_STORE_CTX *x509_ctx)
+{
+  /* XXXX Actually, this needs to get more complicated.  But for now,
+     XXXX always accept peer certs. */
+  return 1;
+}
+
+/* Generate a self-signed certificate with the private key 'rsa' and
+ * commonName 'nickname', and write it, PEM-encoded, to the file named
+ * by 'certfile'.  Return 0 on success, -1 for failure.
+ */
+int
+tor_tls_write_certificate(char *certfile, crypto_pk_env_t *rsa, char *nickname)
+{
+  RSA *_rsa = NULL;
+  time_t start_time, end_time;
+  EVP_PKEY *pkey = NULL;
+  X509 *x509 = NULL;
+  X509_NAME *name = NULL;
+  BIO *out = NULL;
+  int nid;
+  
+  start_time = time(NULL);
+
+  assert(rsa && rsa->type == CRYPTO_PK_RSA);
+  if (!(_rsa = RSAPrivateKey_dup((RSA*)rsa->key)))
+    return -1;
+  if (!(pkey = EVP_PKEY_new()))
+    return -1;
+  if (!(EVP_PKEY_assign_RSA(pkey, _rsa)))
+    return -1;
+  if (!(x509 = X509_new()))
+    return -1;
+  if (!(X509_set_version(x509, 2)))
+    return -1;
+  if (!(ASN1_INTEGER_set(X509_get_serialNumber(x509), (long)start_time)))
+    return -1;
+  
+  if (!(name = X509_NAME_new()))
+    return -1;
+  if ((nid = OBJ_txt2nid("organizationName")) != NID_undef) return -1;
+  if (!(X509_NAME_add_entry_by_NID(name, nid, MBSTRING_ASC,
+                                   "TOR", -1, -1, 0))) return -1;
+  if ((nid = OBJ_txt2nid("commonName")) != NID_undef) return -1;
+  if (!(X509_NAME_add_entry_by_NID(name, nid, MBSTRING_ASC,
+                                   nickname, -1, -1, 0))) return -1;
+  
+  if (!(X509_set_issuer_name(x509, name)))
+    return -1;
+  if (!(X509_set_subject_name(x509, name)))
+    return -1;
+  if (!X509_time_adj(X509_get_notBefore(x509),0,&start_time))
+    return -1;
+  end_time = start_time + 24*60*60*365;
+  if (!X509_time_adj(X509_get_notAfter(x509),0,&end_time))
+    return -1;
+  if (!X509_set_pubkey(x509, pkey))
+    return -1;
+  if (!X509_sign(x509, pkey, EVP_sha1()))
+    return -1;
+  if (!(out = BIO_new_file(certfile, "w")))
+    return -1;
+  if (!(PEM_write_bio_X509(out, x509)))
+    return -1;
+  BIO_free(out);
+  X509_free(x509);
+  EVP_PKEY_free(pkey);
+  X509_NAME_free(name);
+  return 0;
+}
+
+/* Create a new TLS context.  If we are going to be using it as a
+ * server, it must have isServer set to true, certfile set to a
+ * filename for a certificate file, and RSA set to the private key
+ * used for that certificate.
+ */
+tor_tls_context *
+tor_tls_context_new(char *certfile, crypto_pk_env_t *rsa, int isServer)
+{
+  assert(!rsa || rsa->type == CRYPTO_PK_RSA);
+  assert((certfile && rsa) || (!certfile && !rsa));
+  crypto_dh_env_t *dh = NULL;
+  RSA *_rsa = NULL;
+  EVP_PKEY *pkey = NULL;
+  tor_tls_context *result;
+
+  result = tor_malloc(sizeof(tor_tls_context));
+  if (!(result->ctx = SSL_CTX_new(TLSv1_method())))
+    return NULL;
+  /* XXXX This should use AES, but we'll need to require OpenSSL 0.9.7 first */
+  if (!SSL_CTX_set_cipher_list(result->ctx, TLS1_TXT_DHE_DSS_WITH_RC4_128_SHA))
+                               /* TLS1_TXT_DHE_RSA_WITH_AES_128_SHA)) */
+    return NULL;
+  if (certfile && !SSL_CTX_use_certificate_file(result->ctx,certfile,
+                                                SSL_FILETYPE_PEM))
+    return NULL;
+  SSL_CTX_set_session_cache_mode(result->ctx, SSL_SESS_CACHE_OFF);
+  if (rsa) {
+    if (!(_rsa = RSAPrivateKey_dup((RSA*)rsa->key)))
+      return NULL;
+    if (!(pkey = EVP_PKEY_new()))
+      return NULL;
+    if (!EVP_PKEY_assign_RSA(pkey, _rsa))
+      return NULL;
+    if (!SSL_CTX_use_PrivateKey(result->ctx, pkey))
+      return NULL;
+    EVP_PKEY_free(pkey);
+    if (certfile) {
+      if (!SSL_CTX_check_private_key(result->ctx))
+        return NULL;
+    }
+  }
+  dh = crypto_dh_new();
+  SSL_CTX_set_tmp_dh(result->ctx, dh->dh);
+  crypto_dh_free(dh);
+  SSL_CTX_set_verify(result->ctx, SSL_VERIFY_PEER, 
+                     always_accept_verify_cb);
+  
+  return result;
+}
+
+/* Create a new TLS object from a TLS context, a filedescriptor, and 
+ * a flag to determine whether it is functioning as a server.
+ */
+tor_tls *
+tor_tls_new(tor_tls_context *ctx, int sock, int isServer)
+{
+  tor_tls *result = tor_malloc(sizeof(tor_tls));
+  if (!(result->ssl = SSL_new(ctx->ctx)))
+    return NULL;
+  result->socket = sock;
+  SSL_set_fd(result->ssl, sock);
+  result->state = TOR_TLS_ST_HANDSHAKE;
+  result->isServer = isServer;
+  return result;
+}
+
+/* Release resources associated with a TLS object.  Does not close the
+ * underlying file descriptor.
+ */
+void
+tor_tls_free(tor_tls *tls)
+{
+  SSL_free(tls->ssl);
+  free(tls);
+}
+
+/* Underlying function for TLS reading.  Reads up to 'len' characters
+ * from 'tls' into 'cp'.  On success, returns the number of characters
+ * read.  On failure, returns TOR_TLS_ERROR, TOR_TLS_CLOSE,
+ * TOR_TLS_WANTREAD, or TOR_TLS_WANTWRITE.
+ */
+int
+tor_tls_read(tor_tls *tls, char *cp, int len)
+{
+  int r, err;
+  assert(tls && tls->ssl);
+  assert(tls->state == TOR_TLS_ST_OPEN);
+  r = SSL_read(tls->ssl, cp, len);
+  if (r > 0)
+    return r;
+  err = tor_tls_get_error(tls, r, 1);
+  if (err == _TOR_TLS_SYSCALL)
+    return TOR_TLS_ERROR;
+  else if (err == _TOR_TLS_ZERORETURN) {
+    tls->state = TOR_TLS_ST_CLOSED;
+    return TOR_TLS_CLOSE;
+  } else {
+    /*  XXXX Make sure it's not TOR_TLS_DONE. */
+    return err;
+  }
+}
+
+/* Underlying function for TLS writing.  Write up to 'n' characters
+ * from 'cp' onto 'tls'.  On success, returns the number of characters
+ * written.  On failure, returns TOR_TLS_ERROR, TOR_TLS_WANTREAD, 
+ * or TOR_TLS_WANTWRITE.
+ */
+int
+tor_tls_write(tor_tls *tls, char *cp, int n)
+{
+  int r, err;
+  assert(tls && tls->ssl);
+  assert(tls->state == TOR_TLS_ST_OPEN);
+  r = SSL_write(tls->ssl, cp, n);
+  err = tor_tls_get_error(tls, r, 1);
+  if (err == _TOR_TLS_ZERORETURN) {
+    /* should never happen XXXX */
+    return 0;
+  } else if (err == TOR_TLS_DONE) {
+    return r;
+  } else {
+    return err;
+  }  
+}
+
+/* Perform initial handshake on 'tls'.  When finished, returns
+ * TOR_TLS_DONE.  On failure, returns TOR_TLS_ERROR, TOR_TLS_WANTREAD,
+ * or TOR_TLS_WANNTWRITE.
+ */
+int
+tor_tls_handshake(tor_tls *tls)
+{
+  int r;
+  assert(tls && tls->ssl);
+  assert(tls->state == TOR_TLS_ST_HANDSHAKE);
+  if (tls->isServer) {
+    r = SSL_accept(tls->ssl);
+  } else {
+    r = SSL_connect(tls->ssl);
+  }
+  r = tor_tls_get_error(tls,r,0);
+  if (r == TOR_TLS_DONE) {
+    tls->state = TOR_TLS_ST_OPEN; 
+  }
+  return r;
+}
+
+/* Shut down an open tls connection 'tls'.  When finished, returns
+ * TOR_TLS_DONE.  On failure, returns TOR_TLS_ERROR, TOR_TLS_WANTREAD,
+ * or TOR_TLS_WANTWRITE.
+ */
+int
+tor_tls_shutdown(tor_tls *tls)
+{
+  int r, err;
+  char buf[128];
+  assert(tls && tls->ssl);
+
+  if (tls->state == TOR_TLS_ST_SENTCLOSE) {
+    do {
+      r = SSL_read(tls->ssl, buf, 128);
+    } while (r>0);
+    err = tor_tls_get_error(tls, r, 1);
+    if (err == _TOR_TLS_ZERORETURN) {
+      tls->state = TOR_TLS_ST_GOTCLOSE;
+      /* fall through */
+    } else {
+      if (err == _TOR_TLS_SYSCALL)
+        err = TOR_TLS_ERROR;
+      return err;
+    }
+  }
+
+  r = SSL_shutdown(tls->ssl);
+  if (r == 1) {
+    tls->state = TOR_TLS_ST_CLOSED;
+    return TOR_TLS_DONE;
+  }
+  err = tor_tls_get_error(tls, r, 1);
+  if (err == _TOR_TLS_SYSCALL)
+    return TOR_TLS_ST_CLOSED; /* XXXX is this right? */
+  else if (err == _TOR_TLS_ZERORETURN) {
+    if (tls->state == TOR_TLS_ST_GOTCLOSE || 
+        tls->state == TOR_TLS_ST_SENTCLOSE) {
+      /* XXXX log; unexpected. */
+      return TOR_TLS_ERROR;
+    }
+    tls->state = TOR_TLS_ST_SENTCLOSE;
+    return tor_tls_shutdown(tls);
+  } else {
+    /* XXXX log if not error. */
+    return err;
+  }
+}