[elinks-dev] [patch]: negotiate-auth

Karel Zak kzak at redhat.com
Wed Jun 14 05:24:51 PDT 2006


On Wed, Jun 14, 2006 at 09:30:44AM +0200, Zas wrote:
> On Wed, Jun 14, 2006 at 01:49:40AM +0200, Karel Zak wrote:
> > 
> >  Hi guys,
> 
> Hi,
> 
> > 
> >  here is a patch with negotiate-auth support based on GSSAPI. It's
> >  very useful feature for intranet web sites where is possible
> >  authenticate users by Kerberos. (This feature is already implemented
> >  in firefox and libcurl.)
> > 
> 
> This patch looks great, apart from the ELinks style conformity POV ;)
> 
> Have a serious look at doc/hacking.txt, fix the patch accordingly, and
> resubmit it.

 Fixed.

    Karel


 Makefile.config.in                 |    1 
 configure.in                       |   24 +++
 src/protocol/http/Makefile         |    2 
 src/protocol/http/http.c           |   46 ++++--
 src/protocol/http/http_negotiate.c |  290 ++++++++++++++++++++++++++++++++++++
 src/protocol/http/http_negotiate.h |   21 +++
 src/util/base64.c                  |   36 ++++
 src/util/base64.h                  |    3 
 8 files changed, 406 insertions(+), 17 deletions(-)
 create mode 100644 src/protocol/http/http_negotiate.c
 create mode 100644 src/protocol/http/http_negotiate.h

diff --git a/Makefile.config.in b/Makefile.config.in
index 4ab2bf2..8854477 100644
--- a/Makefile.config.in
+++ b/Makefile.config.in
@@ -158,6 +158,7 @@ CONFIG_SYSMOUSE = @CONFIG_SYSMOUSE@
 CONFIG_URI_REWRITE = @CONFIG_URI_REWRITE@
 CONFIG_XBEL_BOOKMARKS = @CONFIG_XBEL_BOOKMARKS@
 CONFIG_XMLTO = @CONFIG_XMLTO@
+CONFIG_GSSAPI = @CONFIG_GSSAPI@
 
 DEFS = @DEFS@
 CFLAGS = @CFLAGS@
diff --git a/configure.in b/configure.in
index 024ebc3..ad2831d 100644
--- a/configure.in
+++ b/configure.in
@@ -453,6 +453,30 @@ fi
 EL_ARG_ENABLE(CONFIG_LZMA, lzma, [lzma],
 	      [  --enable-lzma           enable lzma encoding support])
 dnl ===================================================================
+dnl Check for GSSAPI, optional even if installed.
+dnl ===================================================================
+
+enable_gssapi="no";
+
+AC_ARG_WITH(gssapi, [  --with-gssapi           enable GSSAPI support],
+            [ if test "x$withval" != xno; then enable_gssapi=yes; fi ])
+
+AC_MSG_CHECKING([for GSSAPI])
+
+if test "$enable_gssapi" = "yes"; then
+	AC_MSG_RESULT(yes)
+	GSSAPI_CFLAGS=`krb5-config --cflags gssapi`
+	GSSAPI_LIBS=`krb5-config --libs gssapi`
+	CFLAGS="$GSSAPI_CFLAGS $CFLAGS"
+	LIBS="$GSSAPI_LIBS $LIBS"
+ 	EL_CONFIG(CONFIG_GSSAPI, [GssApi])
+else
+	AC_MSG_RESULT(no)
+fi
+
+AC_SUBST(CONFIG_GSSAPI)
+
+dnl ===================================================================
 dnl Bookmark and XBEL support
 dnl ===================================================================
 
diff --git a/src/protocol/http/Makefile b/src/protocol/http/Makefile
index 10ffb86..fb4dfa0 100644
--- a/src/protocol/http/Makefile
+++ b/src/protocol/http/Makefile
@@ -1,6 +1,8 @@
 top_builddir=../../..
 include $(top_builddir)/Makefile.config
 
+OBJS-$(CONFIG_GSSAPI)	+= http_negotiate.o
+
 OBJS = blacklist.o codes.o http.o
 
 include $(top_srcdir)/Makefile.lib
diff --git a/src/protocol/http/http.c b/src/protocol/http/http.c
index d05a99d..75df08f 100644
--- a/src/protocol/http/http.c
+++ b/src/protocol/http/http.c
@@ -47,6 +47,9 @@ #include "util/conv.h"
 #include "util/memory.h"
 #include "util/string.h"
 
+#ifdef CONFIG_GSSAPI
+#include "http_negotiate.h"
+#endif
 
 struct http_version {
 	int major;
@@ -549,7 +552,7 @@ http_send_header(struct socket *socket)
 	int trace = get_opt_bool("protocol.http.trace");
 	struct string header;
 	unsigned char *post_data = NULL;
-	struct auth_entry *entry;
+	struct auth_entry *entry = NULL;
 	struct uri *uri = conn->proxied_uri; /* Set to the real uri */
 	unsigned char *optstr;
 	int use_connect, talking_to_proxy;
@@ -806,7 +809,11 @@ #endif
 		add_crlf_to_string(&header);
 	}
 
-	entry = find_auth(uri);
+#ifdef CONFIG_GSSAPI
+	if (http_negotiate_output(uri, &header) != 0)
+#endif
+		entry = find_auth(uri);
+	
 	if (entry) {
 		if (entry->digest) {
 			unsigned char *response;
@@ -1325,12 +1332,13 @@ get_header(struct read_buffer *rb)
 	return 0;
 }
 
-
-static void
-check_http_authentication(struct uri *uri, unsigned char *header,
-			  unsigned char *header_field)
+/* returns 1 if we need retry the connection (for negotiate-auth only) */
+static int
+check_http_authentication(struct connection *conn, struct uri *uri, 
+		unsigned char *header, unsigned char *header_field)
 {
 	unsigned char *str, *d;
+	int ret = 0;
 
 	d = parse_header(header, header_field, &str);
 	while (d) {
@@ -1356,10 +1364,24 @@ check_http_authentication(struct uri *ur
 			mem_free(d);
 			break;
 		}
-
+#ifdef CONFIG_GSSAPI
+		else if (!strncasecmp(d, HTTPNEG_GSS_STR, HTTPNEG_GSS_STRLEN)) {
+			if (http_negotiate_input(conn, uri, HTTPNEG_GSS, str)==0)
+				ret = 1;
+			mem_free(d);
+			break;
+		}
+		else if (!strncasecmp(d, HTTPNEG_NEG_STR, HTTPNEG_NEG_STRLEN)) {
+			if (http_negotiate_input(conn, uri, HTTPNEG_NEG, str)==0)
+				ret = 1;
+			mem_free(d);
+			break;
+		}
+#endif
 		mem_free(d);
 		d = parse_header(str, header_field, &str);
 	}
+	return ret;
 }
 
 
@@ -1586,11 +1608,13 @@ #endif
 	}
 
 	if (h == 401) {
-		unsigned char *head = conn->cached->head;
-
-		check_http_authentication(uri, head, "WWW-Authenticate");
+		if (check_http_authentication(conn, uri, 
+				conn->cached->head, "WWW-Authenticate")) {
+			retry_connection(conn, S_RESTART);
+			return;
+		}
+	
 	}
-
 	if (h == 407) {
 		unsigned char *str;
 
diff --git a/src/protocol/http/http_negotiate.c b/src/protocol/http/http_negotiate.c
new file mode 100644
index 0000000..08a8b5d
--- /dev/null
+++ b/src/protocol/http/http_negotiate.c
@@ -0,0 +1,290 @@
+/* 
+ * HTTP Negotiate authentication method -- based on GSSAPI
+ *
+ * The Microsoft version with SPNEGO is unsupported. If you look for way how
+ * extend this code with SPNEGO see libcurl or firefox source code where is
+ * supported GSSAPI+SPNEGO.
+ *
+ * Copyright (C) 2006 Red Hat, Inc.
+ * Karel Zak <kzak at redhat.com> 
+ */
+
+#ifdef HAVE_CONFIG_H
+#include "config.h"
+#endif
+
+#include <stdio.h>
+#include <string.h>
+#include <stdarg.h>
+#include <stdlib.h>
+#include <ctype.h>
+#include <errno.h>
+
+#include <gssapi/gssapi.h>
+
+#include "elinks.h"
+#include "network/connection.h"
+#include "protocol/uri.h"
+#include "protocol/http/http.h"
+#include "protocol/http/http_negotiate.h"
+#include "util/base64.h"
+#include "main/object.h"
+#include "util/lists.h"
+
+struct negotiate {
+	OBJECT_HEAD(struct negotiate);
+
+	struct uri 	*uri;
+	
+	int 		type; 			/* GSS-Negotiate or Negotiate or zero */
+	OM_uint32	status;
+	gss_ctx_id_t	context;
+	gss_name_t	server_name;
+	gss_buffer_desc output_token;
+	gss_buffer_desc input_token;
+};
+
+static INIT_LIST_HEAD(negotiate_list);
+
+static struct negotiate *
+http_negotiate_get(struct uri *uri, int *isnew, int alloc)
+{
+	struct negotiate *neg;
+	
+	foreach (neg, negotiate_list) {	
+		if (compare_uri(neg->uri, uri, URI_HTTP_REFERRER_HOST))
+			return neg;
+	}
+	if (!alloc)	
+		return NULL;
+	if (isnew)
+		*isnew = 1;
+
+	neg = mem_calloc(1, sizeof(*neg));
+	if (!neg)
+		return NULL;
+		
+	neg->uri = get_uri_reference(uri);	
+	
+	return neg;
+}
+
+static void
+http_negotiate_save(struct negotiate *neg)
+{
+	add_to_list(negotiate_list, neg);
+}
+
+static void 
+http_negotiate_cleanup(struct negotiate *neg, int full)
+{
+	OM_uint32 minor_status;
+
+	if (neg->context != GSS_C_NO_CONTEXT)
+		gss_delete_sec_context(&minor_status, &neg->context, GSS_C_NO_BUFFER);
+
+	if (neg->output_token.length != 0)
+		gss_release_buffer(&minor_status, &neg->output_token);
+
+	if (full) {
+		if (neg->server_name)
+			gss_release_name(&minor_status, &neg->server_name);
+
+		if (neg->input_token.length != 0) {
+			/* allocated by mem_free().. so beter not use gss_release_buffer() */
+			mem_free(neg->input_token.value);
+			neg->input_token.length = 0;
+		}	
+	
+		memset(neg, 0, sizeof(*neg));
+	}
+}
+
+static int
+http_negotiate_get_name(struct connection *conn, struct negotiate *neg)
+{
+	OM_uint32 major_status, minor_status;
+	gss_buffer_desc token = GSS_C_EMPTY_BUFFER;
+	char name[2048];
+	const char* service;
+	struct uri *uri = conn->proxied_uri;
+
+	/* GSSAPI implementation by Globus (known as GSI) requires the name to be
+	 * of form "<service>/<fqdn>" instead of <service>@<fqdn> (ie. slash instead
+	 * of at-sign). Also GSI servers are often identified as 'host' not 'khttp'.
+	 * Change following lines if you want to use GSI 
+	 *
+	 * IIS uses the <service>@<fqdn> form but uses 'http' as the service name 
+	 */
+	if (neg->type == HTTPNEG_GSS)
+		service = "KHTTP";
+	else
+		service = "HTTP";
+
+	token.length = strlen(service) + 1 + uri->hostlen + 1;
+	if (token.length + 1 > sizeof(name))
+		return -1;
+
+	snprintf(name, token.length, "%s@%*s", service, uri->hostlen, uri->host);
+
+	token.value = (void *) name;
+	major_status = gss_import_name(&minor_status,
+			 &token,
+			 GSS_C_NT_HOSTBASED_SERVICE,
+			 &neg->server_name);
+
+	return GSS_ERROR(major_status) ? -1 : 0;
+}
+
+static int
+http_negotiate_parse_data(unsigned char *data, int type, 
+			gss_buffer_desc *token)
+{
+	int len = 0;
+	unsigned char *end;
+
+	if (data == NULL || *data == '\0')
+		return 0;
+	
+	data += type == HTTPNEG_GSS ? HTTPNEG_GSS_STRLEN : HTTPNEG_NEG_STRLEN;
+	
+	while(*data && isspace((int)*data)) 
+		data++;
+	
+	if (*data == '\0' || *data == ASCII_CR || *data == ASCII_LF)
+		return 0;	/* no data */
+	
+	end = data;
+	while (isalnum((int) *end) || *end == '=')
+		end++;
+
+	/* Ignore line if we encountered an unexpected char. */
+	if (*end != ASCII_CR && *end != ASCII_LF)
+		return 0;
+
+	len = end - data;
+	
+	if (!len)
+		return 0;
+	
+	token->value = (void *) base64_decode_bin(data, len, &token->length);
+	
+	if (!token->value)
+		return -1;
+
+	return 0;
+}
+
+static int
+http_negotiate_create_context(struct negotiate *neg)
+{
+	OM_uint32 major_status, minor_status;
+
+	major_status = gss_init_sec_context(&minor_status,
+					    GSS_C_NO_CREDENTIAL,
+					    &neg->context,
+					    neg->server_name,
+					    GSS_C_NO_OID,
+					    GSS_C_DELEG_FLAG,
+					    0,
+					    GSS_C_NO_CHANNEL_BINDINGS,
+					    &neg->input_token,
+					    NULL,
+					    &neg->output_token,
+					    NULL,
+					    NULL);
+	neg->status = major_status;
+
+	if (GSS_ERROR(major_status)) 
+		return -1;
+	if (neg->output_token.length == 0) 
+		return -1;
+
+	return 0;
+}
+
+/*
+ * Register new negotiate-auth request
+ *
+ * It's possible that server sends to client input token (at least
+ * libcurl supports it) in WWW-Authenticate header, but ususaly 
+ * is this input token undefined.
+ */
+int 
+http_negotiate_input(struct connection *conn, struct uri *uri, 
+					int type, unsigned char *data)
+{
+	struct negotiate *neg;
+	int ret = 0, isnew = 0;
+
+	neg = http_negotiate_get(uri, &isnew, 1);
+	
+	if (neg->context) {
+		if (type != HTTPNEG_GSS) 
+			return -1;
+	}
+	neg->type = type;
+
+	if (neg->context && neg->status == GSS_S_COMPLETE) {
+		/* We finished succesfully our part of authentication, but
+		 * server rejected it (since we're again here). Exit with an
+		 * error since we can't invent anything better 
+		 */
+		http_negotiate_cleanup(neg, 1);
+		return -1;
+	}
+	if (neg->server_name == NULL && http_negotiate_get_name(conn, neg) < 0)
+		return -1;
+	if (data && http_negotiate_parse_data(data, type, &neg->input_token)) 
+		return -1;
+	ret = http_negotiate_create_context(neg);
+	if (ret == 0 && isnew)
+		http_negotiate_save(neg);
+
+	return ret;
+}
+
+/*
+ * Fill output token to "Authorization: Negotiate <token>".
+ */
+int
+http_negotiate_output(struct uri *uri, struct string *header)
+{
+	struct negotiate *neg;
+	char *encoded = NULL;
+	int len = 0;
+
+	neg = http_negotiate_get(uri, NULL, 0);
+	if (!neg)
+		return -1;
+	
+	if (neg->output_token.length == 0) {
+		if (http_negotiate_create_context(neg) < 0) {		
+			/* full cleanup on error and ask for 
+			 * new WWW-Authenticate from server 
+			 */
+			http_negotiate_cleanup(neg, 1);
+			return -1;
+		}
+	}
+	
+	encoded = base64_encode_bin((unsigned char *) neg->output_token.value, 
+				neg->output_token.length, &len);
+
+	if (encoded == NULL || len == 0)
+		return -1;
+
+	add_to_string(header, "Authorization: ");
+	add_to_string(header, neg->type == HTTPNEG_GSS ? 
+			HTTPNEG_GSS_STR : HTTPNEG_NEG_STR);
+	add_char_to_string(header, ' ');
+	add_to_string(header, encoded);
+	add_crlf_to_string(header);
+	
+	http_negotiate_cleanup(neg, 0);
+
+	mem_free(encoded);
+	
+	return 0;
+}
+
diff --git a/src/protocol/http/http_negotiate.h b/src/protocol/http/http_negotiate.h
new file mode 100644
index 0000000..8666fdd
--- /dev/null
+++ b/src/protocol/http/http_negotiate.h
@@ -0,0 +1,21 @@
+
+#ifndef EL__PROTOCOL_HTTP_HTTP_NEGOTIATE_H
+#define EL__PROTOCOL_HTTP_HTTP_NEGOTIATE_H
+
+#define HTTPNEG_GSS		1
+#define HTTPNEG_NEG		2
+
+#define HTTPNEG_GSS_STR		"GSS-Negotiate"
+#define HTTPNEG_NEG_STR		"Negotiate"
+
+#define HTTPNEG_GSS_STRLEN	sizeof(HTTPNEG_GSS_STR)
+#define HTTPNEG_NEG_STRLEN	sizeof(HTTPNEG_NEG_STR)
+
+int http_negotiate_input(struct connection *conn, struct uri *uri, 
+			int type, unsigned char *data);
+
+int http_negotiate_output(struct uri *uri, struct string *header);
+
+
+#endif /* EL_PROTOCOL_HTTP_HTTP_NEGOTIATE_H */
+
diff --git a/src/util/base64.c b/src/util/base64.c
index 8a3918e..2c2e9ad 100644
--- a/src/util/base64.c
+++ b/src/util/base64.c
@@ -17,14 +17,21 @@ static unsigned char base64_chars[] = "A
 unsigned char *
 base64_encode(register unsigned char *in)
 {
+	assert(in && *in);
+	if_assert_failed return NULL;
+	
+	return base64_encode_bin(in, strlen(in), NULL);
+}
+
+unsigned char *
+base64_encode_bin(register unsigned char *in, int inlen, int *outlen)
+{
 	unsigned char *out;
 	unsigned char *outstr;
-	int inlen;
 
 	assert(in && *in);
 	if_assert_failed return NULL;
 
-	inlen = strlen(in);
 	out = outstr = mem_alloc((inlen / 3) * 4 + 4 + 1);
 	if (!out) return NULL;
 
@@ -49,16 +56,29 @@ base64_encode(register unsigned char *in
 	}
 	*out = 0;
 
+	if (outlen)
+		*outlen = out-outstr;
+
 	return outstr;
 }
 
-/* Base64 decoding is used only with the CONFIG_FORMHIST feature, so i'll #ifdef it */
-#ifdef CONFIG_FORMHIST
+/* Base64 decoding is used only with the CONFIG_FORMHIST or CONFIG_GSSAPI 
+   feature, so i'll #ifdef it */
+#if  defined(CONFIG_FORMHIST) || defined(CONFIG_GSSAPI)
+
+unsigned char *
+base64_decode(register unsigned char *in) 
+{
+	assert(in && *in);
+	if_assert_failed return NULL;
+
+	return base64_decode_bin(in, strlen(in), NULL);
+}
 
 /* base64_decode:  @in string to decode
  *		   returns the string decoded (must be freed by the caller) */
 unsigned char *
-base64_decode(register unsigned char *in)
+base64_decode_bin(register unsigned char *in, int inlen, int *outlen)
 {
 	static unsigned char is_base64_char[256]; /* static to force initialization at zero */
 	static unsigned char decode[256];
@@ -71,7 +91,7 @@ base64_decode(register unsigned char *in
 	assert(in && *in);
 	if_assert_failed return NULL;
 
-	outstr = out = mem_alloc(strlen(in) / 4 * 3 + 1);
+	outstr = out = mem_alloc(inlen / 4 * 3 + 1);
 	if (!outstr) return NULL;
 
 	if (!once) {
@@ -123,6 +143,10 @@ base64_decode(register unsigned char *in
 	}
 
 	*out = 0;
+
+	if (outlen)
+		*outlen = out-outstr;
+
 	return outstr;
 
 decode_error:
diff --git a/src/util/base64.h b/src/util/base64.h
index cb5cd73..2bdf0e4 100644
--- a/src/util/base64.h
+++ b/src/util/base64.h
@@ -4,4 +4,7 @@ #define EL__UTIL_BASE64_H
 unsigned char *base64_encode(unsigned char *);
 unsigned char *base64_decode(unsigned char *);
 
+unsigned char *base64_encode_bin(unsigned char *, int, int *);
+unsigned char *base64_decode_bin(unsigned char *, int, int *);
+
 #endif



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