From b43c30b6b9171da61156495d38d0e2c49bb04421 Mon Sep 17 00:00:00 2001
From: Gerhard Rieger <gerhard@dest-unreach.org>
Date: Sun, 22 Jan 2017 18:48:07 +0100
Subject: [PATCH] Data extraction from ancillary messages might have failed on
 big-endian

---
 CHANGES  |  4 ++++
 xio-ip.c | 23 ++++++++++++++---------
 2 files changed, 18 insertions(+), 9 deletions(-)

diff --git a/CHANGES b/CHANGES
index d2e2c68..8c20c72 100644
--- a/CHANGES
+++ b/CHANGES
@@ -69,6 +69,10 @@ corrections:
 	On systems with predefined bool type whose size differs from int some
 	IPv6 and TCP options (per setsockopt()) failed.
 
+	Length of integral data in ancillary messages varies (TOS: 1 byte,
+	TTL: 4 bytes), the old implementation failed for TTL on big-endian
+	hosts.
+
 porting:
 	Type conflict between int and sig_atomic_t between declaration and
 	definition of diag_immediate_type and diag_immediate_exit broke
diff --git a/xio-ip.c b/xio-ip.c
index cd28f35..67fcd75 100644
--- a/xio-ip.c
+++ b/xio-ip.c
@@ -465,7 +465,8 @@ int xiolog_ancillary_ip(struct cmsghdr *cmsg, int *num,
 			char *nambuff, int namlen,
 			char *envbuff, int envlen,
 			char *valbuff, int vallen) {
-   const char *cmsgtype, *cmsgname = NULL, *cmsgenvn = NULL, *cmsgfmt = NULL;
+   int cmsgctr = 0;
+   const char *cmsgtype, *cmsgname = NULL, *cmsgenvn = NULL;
    size_t msglen;
    char scratch1[16];	/* can hold an IPv4 address in ASCII */
 #if WITH_IP4 && defined(IP_PKTINFO) && HAVE_STRUCT_IN_PKTINFO
@@ -555,17 +556,17 @@ int xiolog_ancillary_ip(struct cmsghdr *cmsg, int *num,
 #ifdef IP_RECVOPTS
    case IP_RECVOPTS:
 #endif
-      cmsgtype = "IP_OPTIONS"; cmsgname = "options"; cmsgfmt = NULL; break;
+      cmsgtype = "IP_OPTIONS"; cmsgname = "options"; cmsgctr = -1; break;
    case IP_TOS:
-      cmsgtype = "IP_TOS";     cmsgname = "tos"; cmsgfmt = "%u"; break;
+      cmsgtype = "IP_TOS";     cmsgname = "tos"; cmsgctr = msglen; break;
    case IP_TTL: /* Linux */
 #ifdef IP_RECVTTL
    case IP_RECVTTL: /* FreeBSD */
 #endif
-      cmsgtype = "IP_TTL";     cmsgname = "ttl"; cmsgfmt = "%u"; break;
+      cmsgtype = "IP_TTL";     cmsgname = "ttl"; cmsgctr = msglen; break;
    }
    /* when we come here we provide a single parameter
-      with type in cmsgtype, name in cmsgname, printf format in cmsgfmt */
+      with type in cmsgtype, name in cmsgname, value length in msglen */
    *num = 1;
    if (strlen(cmsgtype) >= typlen)  rc = STAT_WARNING;
    typbuff[0] = '\0'; strncat(typbuff, cmsgtype, typlen-1);
@@ -577,10 +578,14 @@ int xiolog_ancillary_ip(struct cmsghdr *cmsg, int *num,
    } else {
       envbuff[0] = '\0';
    }
-   if (cmsgfmt != NULL) {
-      snprintf(valbuff, vallen, cmsgfmt, *(unsigned char *)CMSG_DATA(cmsg));
-   } else {
-      xiodump(CMSG_DATA(cmsg), msglen, valbuff, vallen, 0);
+   switch (cmsgctr) {
+   case sizeof(char):
+      snprintf(valbuff, vallen, "%u", *(unsigned char *)CMSG_DATA(cmsg)); break;
+   case sizeof(int):
+      snprintf(valbuff, vallen, "%u",    (*(unsigned int *)CMSG_DATA(cmsg))); break;
+   case 0:
+      xiodump(CMSG_DATA(cmsg), msglen, valbuff, vallen, 0); break;
+   default: break;
    }
    return rc;
 }