iproute2: allow to specify truncation bits on auth algo

Hi,

here is a patch against iproute2 to allow user to set a state with a specific
auth length.

Example:
$ ip xfrm state add src 10.16.0.72 dst 10.16.0.121 proto ah spi 0x10000000
auth-trunc "sha256" "azertyuiopqsdfghjklmwxcvbn123456" 96 mode tunnel
$ ip xfrm state
src 10.16.0.72 dst 10.16.0.121
         proto ah spi 0x10000000 reqid 0 mode tunnel
         replay-window 0
         auth-trunc hmac(sha256)
0x617a6572747975696f707173646667686a6b6c6d77786376626e313233343536 96
         sel src 0.0.0.0/0 dst 0.0.0.0/0

Regards,
Nicolas

>From 522ed7348cdf3b6f501af2a5a5d989de1696565a Mon Sep 17 00:00:00 2001
From: Nicolas Dichtel <nicolas.dichtel@6wind.com>
Date: Thu, 23 Dec 2010 06:48:12 -0500
Subject: [PATCH] iproute2: allow to specify truncation bits on auth algo

Attribute XFRMA_ALG_AUTH_TRUNC can be used to specify
truncation bits, so we add a new algo type: auth-trunc.

Signed-off-by: Nicolas Dichtel <nicolas.dichtel@6wind.com>
diff --git a/ip/ipxfrm.c b/ip/ipxfrm.c
index cc4dc80..a276c0b 100644
--- a/ip/ipxfrm.c
+++ b/ip/ipxfrm.c
@@ -155,6 +155,7 @@
 static const struct typeent algo_types[]= {
 	{ "enc", XFRMA_ALG_CRYPT }, { "auth", XFRMA_ALG_AUTH },
 	{ "comp", XFRMA_ALG_COMP }, { "aead", XFRMA_ALG_AEAD },
+	{ "auth-trunc", XFRMA_ALG_AUTH_TRUNC },
 	{ NULL, -1 }
 };
 
@@ -570,6 +571,25 @@
 	fprintf(fp, "%s", _SL_);
 }
 
+static void xfrm_auth_trunc_print(struct xfrm_algo_auth *algo, int len,
+				  FILE *fp, const char *prefix)
+{
+	struct {
+		struct xfrm_algo algo;
+		char key[algo->alg_key_len / 8];
+	} base;
+
+	memcpy(base.algo.alg_name, algo->alg_name, sizeof(base.algo.alg_name));
+	base.algo.alg_key_len = algo->alg_key_len;
+	memcpy(base.algo.alg_key, algo->alg_key, algo->alg_key_len / 8);
+
+	__xfrm_algo_print(&base.algo, XFRMA_ALG_AUTH_TRUNC, len, fp, prefix, 0);
+
+	fprintf(fp, " %d", algo->alg_trunc_len);
+
+	fprintf(fp, "%s", _SL_);
+}
+
 static void xfrm_tmpl_print(struct xfrm_user_tmpl *tmpls, int len,
 			    __u16 family, FILE *fp, const char *prefix)
 {
@@ -677,12 +697,18 @@
 		fprintf(fp, "\tmark %d/0x%x\n", m->v, m->m);
 	}
 
-	if (tb[XFRMA_ALG_AUTH]) {
+	if (tb[XFRMA_ALG_AUTH] && !tb[XFRMA_ALG_AUTH_TRUNC]) {
 		struct rtattr *rta = tb[XFRMA_ALG_AUTH];
 		xfrm_algo_print((struct xfrm_algo *) RTA_DATA(rta),
 				XFRMA_ALG_AUTH, RTA_PAYLOAD(rta), fp, prefix);
 	}
 
+	if (tb[XFRMA_ALG_AUTH_TRUNC]) {
+		struct rtattr *rta = tb[XFRMA_ALG_AUTH_TRUNC];
+		xfrm_auth_trunc_print((struct xfrm_algo_auth *) RTA_DATA(rta),
+				      RTA_PAYLOAD(rta), fp, prefix);
+	}
+
 	if (tb[XFRMA_ALG_AEAD]) {
 		struct rtattr *rta = tb[XFRMA_ALG_AEAD];
 		xfrm_aead_print((struct xfrm_algo_aead *)RTA_DATA(rta),