[MAJOR] implement tcp request content inspection
Some people need to inspect contents of TCP requests before
deciding to forward a connection or not. A future extension
of this demand might consist in selecting a server farm
depending on the protocol detected in the request.
For this reason, a new state CL_STINSPECT has been added on
the client side. It is immediately entered upon accept() if
the statement "tcp-request inspect-delay <xxx>" is found in
the frontend configuration. Haproxy will then wait up to
this amount of time trying to find a matching ACL, and will
either accept or reject the connection depending on the
"tcp-request content <action> {if|unless}" rules, where
<action> is either "accept" or "reject".
Note that it only waits that long if no definitive verdict
can be found earlier. That generally implies calling a fetch()
function which does not have enough information to decode
some contents, or a match() function which only finds the
beginning of what it's looking for.
It is only at the ACL level that partial data may be processed
as such, because we need to distinguish between MISS and FAIL
*before* applying the term negation.
Thus it is enough to add "| ACL_PARTIAL" to the last argument
when calling acl_exec_cond() to indicate that we expect
ACL_PAT_MISS to be returned if some data is missing (for
fetch() or match()). This is the only case we may return
this value. For this reason, the ACL check in process_cli()
has become a lot simpler.
A new ACL "req_len" of type "int" has been added. Right now
it is already possible to drop requests which talk too early
(eg: for SMTP) or which don't talk at all (eg: HTTP/SSL).
Also, the acl fetch() functions have been extended in order
to permit reporting of missing data in case of fetch failure,
using the ACL_TEST_F_MAY_CHANGE flag.
The default behaviour is unchanged, and if no rule matches,
the request is accepted.
As a side effect, all layer 7 fetching functions have been
cleaned up so that they now check for the validity of the
layer 7 pointer before dereferencing it.
diff --git a/src/proto_tcp.c b/src/proto_tcp.c
index d122a03..e2afb94 100644
--- a/src/proto_tcp.c
+++ b/src/proto_tcp.c
@@ -24,6 +24,7 @@
#include <sys/types.h>
#include <sys/un.h>
+#include <common/cfgparse.h>
#include <common/compat.h>
#include <common/config.h>
#include <common/debug.h>
@@ -47,6 +48,7 @@
#include <proto/fd.h>
#include <proto/protocols.h>
#include <proto/proto_tcp.h>
+#include <proto/proxy.h>
#include <proto/queue.h>
#include <proto/senddata.h>
#include <proto/session.h>
@@ -329,11 +331,139 @@
proto_tcpv6.nb_listeners++;
}
+/* This function should be called to parse a line starting with the "tcp-request"
+ * keyword.
+ */
+static int tcp_parse_tcp_req(char **args, int section_type, struct proxy *curpx,
+ struct proxy *defpx, char *err, int errlen)
+{
+ const char *ptr = NULL;
+ int val;
+ int retlen;
+
+ if (!*args[1]) {
+ snprintf(err, errlen, "missing argument for '%s' in %s '%s'",
+ args[0], proxy_type_str(proxy), curpx->id);
+ return -1;
+ }
+
+ if (!strcmp(args[1], "inspect-delay")) {
+ if (curpx == defpx) {
+ snprintf(err, errlen, "%s %s is not allowed in 'defaults' sections",
+ args[0], args[1]);
+ return -1;
+ }
+
+ if (!(curpx->cap & PR_CAP_FE)) {
+ snprintf(err, errlen, "%s %s will be ignored because %s '%s' has no %s capability",
+ args[0], args[1], proxy_type_str(proxy), curpx->id,
+ "frontend");
+ return 1;
+ }
+
+ if (!*args[2] || (ptr = parse_time_err(args[2], &val, TIME_UNIT_MS))) {
+ retlen = snprintf(err, errlen,
+ "'%s %s' expects a positive delay in milliseconds, in %s '%s'",
+ args[0], args[1], proxy_type_str(proxy), curpx->id);
+ if (ptr && retlen < errlen)
+ retlen += snprintf(err+retlen, errlen - retlen,
+ " (unexpected character '%c')", *ptr);
+ return -1;
+ }
+
+ if (curpx->tcp_req.inspect_delay) {
+ snprintf(err, errlen, "ignoring %s %s (was already defined) in %s '%s'",
+ args[0], args[1], proxy_type_str(proxy), curpx->id);
+ return 1;
+ }
+ curpx->tcp_req.inspect_delay = val;
+ return 0;
+ }
+
+ if (!strcmp(args[1], "content")) {
+ int action;
+ int pol = ACL_COND_NONE;
+ struct acl_cond *cond;
+ struct tcp_rule *rule;
+
+ if (curpx == defpx) {
+ snprintf(err, errlen, "%s %s is not allowed in 'defaults' sections",
+ args[0], args[1]);
+ return -1;
+ }
+
+ if (!strcmp(args[2], "accept"))
+ action = TCP_ACT_ACCEPT;
+ else if (!strcmp(args[2], "reject"))
+ action = TCP_ACT_REJECT;
+ else {
+ retlen = snprintf(err, errlen,
+ "'%s %s' expects 'accept' or 'reject', in %s '%s' (was '%s')",
+ args[0], args[1], proxy_type_str(curpx), curpx->id, args[2]);
+ return -1;
+ }
+
+ pol = ACL_COND_NONE;
+ cond = NULL;
+
+ if (!strcmp(args[3], "if"))
+ pol = ACL_COND_IF;
+ else if (!strcmp(args[3], "unless"))
+ pol = ACL_COND_UNLESS;
+
+ /* Note: we consider "if TRUE" when there is no condition */
+ if (pol != ACL_COND_NONE &&
+ (cond = parse_acl_cond((const char **)args+4, &curpx->acl, pol)) == NULL) {
+ retlen = snprintf(err, errlen,
+ "Error detected in %s '%s' while parsing '%s' condition",
+ proxy_type_str(curpx), curpx->id, args[3]);
+ return -1;
+ }
+
+ rule = (struct tcp_rule *)calloc(1, sizeof(*rule));
+ rule->cond = cond;
+ rule->action = action;
+ LIST_INIT(&rule->list);
+ LIST_ADDQ(&curpx->tcp_req.inspect_rules, &rule->list);
+ return 0;
+ }
+
+ snprintf(err, errlen, "unknown argument '%s' after '%s' in %s '%s'",
+ args[1], args[0], proxy_type_str(proxy), curpx->id);
+ return -1;
+}
+
+/* return the number of bytes in the request buffer */
+static int
+acl_fetch_req_len(struct proxy *px, struct session *l4, void *l7, int dir,
+ struct acl_expr *expr, struct acl_test *test)
+{
+ if (!l4 || !l4->req)
+ return 0;
+
+ test->i = l4->req->l;
+ test->flags = ACL_TEST_F_VOLATILE | ACL_TEST_F_MAY_CHANGE;
+ return 1;
+}
+
+
+static struct cfg_kw_list cfg_kws = {{ },{
+ { CFG_LISTEN, "tcp-request", tcp_parse_tcp_req },
+ { 0, NULL, NULL },
+}};
+
+static struct acl_kw_list acl_kws = {{ },{
+ { "req_len", acl_parse_int, acl_fetch_req_len, acl_match_int },
+ { NULL, NULL, NULL, NULL },
+}};
+
__attribute__((constructor))
static void __tcp_protocol_init(void)
{
protocol_register(&proto_tcpv4);
protocol_register(&proto_tcpv6);
+ cfg_register_keywords(&cfg_kws);
+ acl_register_keywords(&acl_kws);
}