static int check_chain_extensions(X509_STORE_CTX *ctx)
{
#ifdef OPENSSL_NO_CHAIN_VERIFY
	return 1;
#else
	int i, ok=0, must_be_ca, plen = 0;
	X509 *x;
	int (*cb)(int xok,X509_STORE_CTX *xctx);
	int proxy_path_length = 0;
	int purpose;
	int allow_proxy_certs;
	cb=ctx->verify_cb;
	must_be_ca = -1;
	if (ctx->parent)
		{
		allow_proxy_certs = 0;
		purpose = X509_PURPOSE_CRL_SIGN;
		}
	else
		{
		allow_proxy_certs =
			!!(ctx->param->flags & X509_V_FLAG_ALLOW_PROXY_CERTS);
		if (getenv("OPENSSL_ALLOW_PROXY_CERTS"))
			allow_proxy_certs = 1;
		purpose = ctx->param->purpose;
		}
	for (i = 0; i < ctx->last_untrusted; i++)
		{
		int ret;
		x = sk_X509_value(ctx->chain, i);
		if (!(ctx->param->flags & X509_V_FLAG_IGNORE_CRITICAL)
			&& (x->ex_flags & EXFLAG_CRITICAL))
			{
			ctx->error = X509_V_ERR_UNHANDLED_CRITICAL_EXTENSION;
			ctx->error_depth = i;
			ctx->current_cert = x;
			ok=cb(0,ctx);
			if (!ok) goto end;
			}
		if (!allow_proxy_certs && (x->ex_flags & EXFLAG_PROXY))
			{
			ctx->error = X509_V_ERR_PROXY_CERTIFICATES_NOT_ALLOWED;
			ctx->error_depth = i;
			ctx->current_cert = x;
			ok=cb(0,ctx);
			if (!ok) goto end;
			}
		ret = X509_check_ca(x);
		switch(must_be_ca)
			{
		case -1:
			if ((ctx->param->flags & X509_V_FLAG_X509_STRICT)
				&& (ret != 1) && (ret != 0))
				{
				ret = 0;
				ctx->error = X509_V_ERR_INVALID_CA;
				}
			else
				ret = 1;
			break;
		case 0:
			if (ret != 0)
				{
				ret = 0;
				ctx->error = X509_V_ERR_INVALID_NON_CA;
				}
			else
				ret = 1;
			break;
		default:
			if ((ret == 0)
				|| ((ctx->param->flags & X509_V_FLAG_X509_STRICT)
					&& (ret != 1)))
				{
				ret = 0;
				ctx->error = X509_V_ERR_INVALID_CA;
				}
			else
				ret = 1;
			break;
			}
		if (ret == 0)
			{
			ctx->error_depth = i;
			ctx->current_cert = x;
			ok=cb(0,ctx);
			if (!ok) goto end;
			}
		if (ctx->param->purpose > 0)
			{
			ret = X509_check_purpose(x, purpose, must_be_ca > 0);
			if ((ret == 0)
				|| ((ctx->param->flags & X509_V_FLAG_X509_STRICT)
					&& (ret != 1)))
				{
				ctx->error = X509_V_ERR_INVALID_PURPOSE;
				ctx->error_depth = i;
				ctx->current_cert = x;
				ok=cb(0,ctx);
				if (!ok) goto end;
				}
			}
		if ((i > 1) && !(x->ex_flags & EXFLAG_SI)
			   && (x->ex_pathlen != -1)
			   && (plen > (x->ex_pathlen + proxy_path_length + 1)))
			{
			ctx->error = X509_V_ERR_PATH_LENGTH_EXCEEDED;
			ctx->error_depth = i;
			ctx->current_cert = x;
			ok=cb(0,ctx);
			if (!ok) goto end;
			}
		if (!(x->ex_flags & EXFLAG_SI))
			plen++;
		if (x->ex_flags & EXFLAG_PROXY)
			{
			if (x->ex_pcpathlen != -1 && i > x->ex_pcpathlen)
				{
				ctx->error =
					X509_V_ERR_PROXY_PATH_LENGTH_EXCEEDED;
				ctx->error_depth = i;
				ctx->current_cert = x;
				ok=cb(0,ctx);
				if (!ok) goto end;
				}
			proxy_path_length++;
			must_be_ca = 0;
			}
		else
			must_be_ca = 1;
		}
	ok = 1;
 end:
	return ok;
#endif
}
['static int check_chain_extensions(X509_STORE_CTX *ctx)\n{\n#ifdef OPENSSL_NO_CHAIN_VERIFY\n\treturn 1;\n#else\n\tint i, ok=0, must_be_ca, plen = 0;\n\tX509 *x;\n\tint (*cb)(int xok,X509_STORE_CTX *xctx);\n\tint proxy_path_length = 0;\n\tint purpose;\n\tint allow_proxy_certs;\n\tcb=ctx->verify_cb;\n\tmust_be_ca = -1;\n\tif (ctx->parent)\n\t\t{\n\t\tallow_proxy_certs = 0;\n\t\tpurpose = X509_PURPOSE_CRL_SIGN;\n\t\t}\n\telse\n\t\t{\n\t\tallow_proxy_certs =\n\t\t\t!!(ctx->param->flags & X509_V_FLAG_ALLOW_PROXY_CERTS);\n\t\tif (getenv("OPENSSL_ALLOW_PROXY_CERTS"))\n\t\t\tallow_proxy_certs = 1;\n\t\tpurpose = ctx->param->purpose;\n\t\t}\n\tfor (i = 0; i < ctx->last_untrusted; i++)\n\t\t{\n\t\tint ret;\n\t\tx = sk_X509_value(ctx->chain, i);\n\t\tif (!(ctx->param->flags & X509_V_FLAG_IGNORE_CRITICAL)\n\t\t\t&& (x->ex_flags & EXFLAG_CRITICAL))\n\t\t\t{\n\t\t\tctx->error = X509_V_ERR_UNHANDLED_CRITICAL_EXTENSION;\n\t\t\tctx->error_depth = i;\n\t\t\tctx->current_cert = x;\n\t\t\tok=cb(0,ctx);\n\t\t\tif (!ok) goto end;\n\t\t\t}\n\t\tif (!allow_proxy_certs && (x->ex_flags & EXFLAG_PROXY))\n\t\t\t{\n\t\t\tctx->error = X509_V_ERR_PROXY_CERTIFICATES_NOT_ALLOWED;\n\t\t\tctx->error_depth = i;\n\t\t\tctx->current_cert = x;\n\t\t\tok=cb(0,ctx);\n\t\t\tif (!ok) goto end;\n\t\t\t}\n\t\tret = X509_check_ca(x);\n\t\tswitch(must_be_ca)\n\t\t\t{\n\t\tcase -1:\n\t\t\tif ((ctx->param->flags & X509_V_FLAG_X509_STRICT)\n\t\t\t\t&& (ret != 1) && (ret != 0))\n\t\t\t\t{\n\t\t\t\tret = 0;\n\t\t\t\tctx->error = X509_V_ERR_INVALID_CA;\n\t\t\t\t}\n\t\t\telse\n\t\t\t\tret = 1;\n\t\t\tbreak;\n\t\tcase 0:\n\t\t\tif (ret != 0)\n\t\t\t\t{\n\t\t\t\tret = 0;\n\t\t\t\tctx->error = X509_V_ERR_INVALID_NON_CA;\n\t\t\t\t}\n\t\t\telse\n\t\t\t\tret = 1;\n\t\t\tbreak;\n\t\tdefault:\n\t\t\tif ((ret == 0)\n\t\t\t\t|| ((ctx->param->flags & X509_V_FLAG_X509_STRICT)\n\t\t\t\t\t&& (ret != 1)))\n\t\t\t\t{\n\t\t\t\tret = 0;\n\t\t\t\tctx->error = X509_V_ERR_INVALID_CA;\n\t\t\t\t}\n\t\t\telse\n\t\t\t\tret = 1;\n\t\t\tbreak;\n\t\t\t}\n\t\tif (ret == 0)\n\t\t\t{\n\t\t\tctx->error_depth = i;\n\t\t\tctx->current_cert = x;\n\t\t\tok=cb(0,ctx);\n\t\t\tif (!ok) goto end;\n\t\t\t}\n\t\tif (ctx->param->purpose > 0)\n\t\t\t{\n\t\t\tret = X509_check_purpose(x, purpose, must_be_ca > 0);\n\t\t\tif ((ret == 0)\n\t\t\t\t|| ((ctx->param->flags & X509_V_FLAG_X509_STRICT)\n\t\t\t\t\t&& (ret != 1)))\n\t\t\t\t{\n\t\t\t\tctx->error = X509_V_ERR_INVALID_PURPOSE;\n\t\t\t\tctx->error_depth = i;\n\t\t\t\tctx->current_cert = x;\n\t\t\t\tok=cb(0,ctx);\n\t\t\t\tif (!ok) goto end;\n\t\t\t\t}\n\t\t\t}\n\t\tif ((i > 1) && !(x->ex_flags & EXFLAG_SI)\n\t\t\t   && (x->ex_pathlen != -1)\n\t\t\t   && (plen > (x->ex_pathlen + proxy_path_length + 1)))\n\t\t\t{\n\t\t\tctx->error = X509_V_ERR_PATH_LENGTH_EXCEEDED;\n\t\t\tctx->error_depth = i;\n\t\t\tctx->current_cert = x;\n\t\t\tok=cb(0,ctx);\n\t\t\tif (!ok) goto end;\n\t\t\t}\n\t\tif (!(x->ex_flags & EXFLAG_SI))\n\t\t\tplen++;\n\t\tif (x->ex_flags & EXFLAG_PROXY)\n\t\t\t{\n\t\t\tif (x->ex_pcpathlen != -1 && i > x->ex_pcpathlen)\n\t\t\t\t{\n\t\t\t\tctx->error =\n\t\t\t\t\tX509_V_ERR_PROXY_PATH_LENGTH_EXCEEDED;\n\t\t\t\tctx->error_depth = i;\n\t\t\t\tctx->current_cert = x;\n\t\t\t\tok=cb(0,ctx);\n\t\t\t\tif (!ok) goto end;\n\t\t\t\t}\n\t\t\tproxy_path_length++;\n\t\t\tmust_be_ca = 0;\n\t\t\t}\n\t\telse\n\t\t\tmust_be_ca = 1;\n\t\t}\n\tok = 1;\n end:\n\treturn ok;\n#endif\n}', 'void *sk_value(const _STACK *st, int i)\n{\n\tif(!st || (i < 0) || (i >= st->num)) return NULL;\n\treturn st->data[i];\n}']