# HG changeset patch
# User Paul Aurich <paul@darkrain42.org>
# Date 1290312251 28800
# Node ID 8c61b29d87ecf6c25f17b1f4e2c79b0472bf097d
# Parent  3e0325d39a61ee7c311d5bd89288187a4f7a482c
context: support for diffie-hellman key exchange

diff -r 3e0325d39a61 -r 8c61b29d87ec src/context.c
--- a/src/context.c	Sun Nov 07 17:12:33 2010 -0800
+++ b/src/context.c	Sat Nov 20 20:04:11 2010 -0800
@@ -19,6 +19,46 @@
 };
 typedef struct ssl_option_s ssl_option_t;
 
+/* The export DH key */
+static DH *dh_512    = NULL;
+/* The larger key (builtin is 2048, caller may specify larger) */
+static DH *dh_larger = NULL;
+
+/* Generated via "openssl dhparam -2 -noout -C 512 2>/dev/null" */
+static unsigned char dh512_p[] = {
+  0xE4,0x3F,0x75,0x82,0xAD,0x0B,0x28,0xC7,0xEF,0xCE,0xBC,0x3B,
+  0x14,0xBB,0xA6,0xF4,0xA2,0xE9,0xA6,0x59,0xCF,0x97,0x1C,0x86,
+  0x43,0x3B,0x92,0x4A,0x6B,0x15,0x4B,0x0C,0xAC,0x8F,0xFA,0x43,
+  0xE2,0xA8,0xC3,0x3B,0x7B,0x51,0x1B,0x46,0x21,0xBF,0x8C,0x06,
+  0x6C,0xB1,0x49,0x75,0xC7,0xAC,0x47,0x1D,0x9D,0x64,0xD5,0x99,
+  0x33,0x86,0xAD,0xEB,
+};
+
+/* Generated via "openssl dhparam -2 -noout -C 2048 2>/dev/null" */
+static unsigned char dh2048_p[] = {
+  0x9B,0xF4,0xC5,0x57,0x81,0x8F,0xCF,0x31,0x78,0x95,0x04,0xCD,
+  0xEA,0xCC,0x30,0xEA,0xF7,0xCA,0x76,0xC8,0x8F,0x91,0xEA,0x0E,
+  0x44,0x8D,0xE2,0x63,0x19,0x3B,0x4D,0x04,0xC8,0x7D,0x0D,0xFF,
+  0x3D,0x52,0x76,0x02,0xF3,0xCA,0x1C,0x44,0xAF,0x0E,0xA9,0x59,
+  0x02,0x40,0x75,0xD6,0xED,0x35,0x4D,0x11,0x5B,0x2B,0x73,0x23,
+  0xE5,0x53,0x0B,0x1F,0xB0,0x47,0xC4,0x7F,0x95,0x5D,0xB0,0xD5,
+  0xF3,0xD3,0xAB,0x5F,0x28,0x2B,0xEC,0x2C,0x15,0x0B,0x1B,0x0C,
+  0xD4,0xBE,0x24,0x2F,0xC5,0x07,0x3C,0xE4,0xC5,0xE6,0x16,0x42,
+  0x4C,0x31,0x04,0xBB,0x80,0x96,0xFF,0x64,0x50,0xA4,0xA5,0xB5,
+  0xF5,0x3A,0xBA,0x57,0xE4,0xE6,0xC2,0x23,0x0A,0xB6,0x27,0xC4,
+  0x06,0x01,0x1E,0x98,0x20,0x09,0xC8,0xB7,0x90,0x09,0x86,0x06,
+  0xAA,0x85,0xE7,0x02,0xC8,0xC6,0xD9,0x1D,0xAB,0x17,0xEE,0x78,
+  0x73,0x78,0x88,0x7F,0xA7,0xF2,0x34,0xA7,0xDD,0x02,0x16,0x36,
+  0x0D,0x77,0x16,0x3E,0x95,0xAE,0x02,0xEE,0x36,0x37,0xD5,0x61,
+  0x5D,0xFE,0xC6,0x0B,0xDF,0xCE,0xB9,0x26,0x31,0x6F,0x34,0x92,
+  0xBB,0xBB,0x91,0x29,0x77,0x62,0x1D,0x75,0xA0,0x51,0x8D,0x31,
+  0x4C,0x64,0x4E,0xBF,0xDC,0xE8,0x67,0x17,0x90,0x6A,0x80,0xE9,
+  0xD7,0xD8,0x56,0x4E,0x85,0x21,0x9C,0xFB,0xE6,0x1B,0xD8,0x05,
+  0xFD,0x13,0x77,0x00,0x96,0x2D,0x0C,0x2A,0x95,0x1A,0x08,0x82,
+  0x2E,0xB3,0xE2,0xFC,0xE8,0xA6,0xF1,0x16,0x37,0x57,0x82,0xD6,
+  0xF5,0xAB,0xA9,0x43,0x8F,0x33,0xB0,0x57,0x38,0x6E,0x61,0xD4,
+  0xDD,0xE0,0x1C,0xCB,
+};
 
 static ssl_option_t ssl_options[] = {
   /* OpenSSL 0.9.7 and 0.9.8 */
@@ -143,6 +183,38 @@
   return 0;
 }
 
+static DH *get_dh(const unsigned char *p, int len)
+{
+  DH *dh = NULL;
+  static unsigned char g[] = { 0x02 };
+
+  if ((dh = DH_new()) == NULL) return NULL;
+  dh->p = BN_bin2bn(p, len, NULL);
+  dh->g = BN_bin2bn(g, sizeof(g), NULL);
+  if (dh->p == NULL || dh->g == NULL) {
+    DH_free(dh);
+    return NULL;
+  }
+
+  return dh;
+}
+
+/**
+ * DH parameter callback
+ */
+static DH *dh_param_cb(SSL *ssl, int is_export, int keylength)
+{
+  /* Logic in postfix and dovecot, but we're using a 2048-bit group... */
+  if (is_export && keylength == 512) {
+    if (dh_512 == NULL) { dh_512 = get_dh(dh512_p, sizeof(dh512_p)); }
+    return dh_512;
+  } else {
+    if (dh_larger == NULL) { dh_larger = get_dh(dh2048_p, sizeof(dh2048_p)); }
+    return dh_larger;
+  }
+}
+
+
 /*------------------------------ Lua Functions -------------------------------*/
 
 /**
@@ -174,6 +246,11 @@
   ctx->mode = MD_CTX_INVALID;
   /* No session support */
   SSL_CTX_set_session_cache_mode(ctx->context, SSL_SESS_CACHE_OFF);
+  /*
+   * Support ephemeral diffie-hellman key exchange.  This is only needed
+   * for server mode, but clearer to put it here rather than set_mode.
+   */
+  SSL_CTX_set_tmp_dh_callback(ctx->context, dh_param_cb);
   luaL_getmetatable(L, "SSL:Context");
   lua_setmetatable(L, -2);
   return 1;
@@ -248,6 +325,41 @@
 }
 
 /**
+ * Load a DH params files.  This is a global LuaSec thing.
+ */
+static int load_dhparams(lua_State *L)
+{
+  const char *filename = luaL_checkstring(L, 1);
+  FILE *paramfile;
+  DH *dh;
+
+  paramfile = fopen(filename, "r");
+  if (!paramfile) {
+    lua_pushboolean(L, 0);
+    lua_pushfstring(L, "error reading dh param file %s: %s", filename,
+      strerror(errno));
+    return 2;
+  }
+
+  dh = PEM_read_DHparams(paramfile, NULL, NULL, NULL);
+  fclose(paramfile);
+  if (!dh) {
+    lua_pushboolean(L, 0);
+    lua_pushfstring(L, "error loading dh param file %s: %s", filename,
+      ERR_reason_error_string(ERR_get_error()));
+    return 2;
+  }
+
+  if (dh_larger)
+    DH_free(dh_larger);
+
+  dh_larger = dh;
+
+  lua_pushboolean(L, 1);
+  return 1;
+}
+
+/**
  * Set the cipher list.
  */
 static int set_cipher(lua_State *L)
@@ -369,6 +481,7 @@
   {"setoptions", set_options},
   {"setmode",    set_mode},
   {"rawcontext", raw_ctx},
+  {"loaddhparams", load_dhparams},
   {NULL, NULL}
 };
 
diff -r 3e0325d39a61 -r 8c61b29d87ec src/ssl.lua
--- a/src/ssl.lua	Sun Nov 07 17:12:33 2010 -0800
+++ b/src/ssl.lua	Sat Nov 20 20:04:11 2010 -0800
@@ -18,6 +18,7 @@
 -- Export functions
 rawconnection = core.rawconnection
 rawcontext    = context.rawcontext
+loaddhparams  = context.loaddhparams
 
 cert_from_pem = x509.cert_from_pem