fixing resolver part 2: make _res structure members

 configurable. we don't use most of it anyway.

3 files changed, 74 insertions, 39 deletions

diff --git a/extra/Configs/Config.in b/extra/Configs/Config.in
index 9e2112c84..4979d5822 100644
--- a/extra/Configs/Config.in
+++ b/extra/Configs/Config.in
@@ -772,7 +772,7 @@ config UCLIBC_HAS_OBSOLETE_BSD_SIGNAL
 	bool "BSD obsolete signal functions"
 	default n
 	help
-	  These  functions are provided as a compatibility interface for
+	  These functions are provided as a compatibility interface for
 	  programs that make use of the historical System V signal API.
 	  This API is obsolete:
 	  new applications should use the POSIX signal API (sigaction(2),
@@ -1066,6 +1066,23 @@ config UCLIBC_HAS_BSD_RES_CLOSE
 
 	  Most people will say N.
 
+config UCLIBC_HAS_COMPAT_RES_STATE
+	bool "Use compatible but bloated _res"
+	default y
+	help
+	  Answer Y if you build network utilities and they muck with resolver
+	  internals a lot (_res global structure). uclibc does not use most
+	  of _res.XXX fields, and with this option OFF they won't even exist.
+	  Which will make e.g. dig build fail.
+	  Answering N saves around 400 bytes in bss.
+
+config UCLIBC_HAS_EXTRA_COMPAT_RES_STATE
+	bool "Use extra compatible but extra bloated _res"
+	default n
+	help
+	  Answer Y if selecting UCLIBC_HAS_COMPAT_RES_STATE is not enough.
+	  As far as I can say, this should never be needed.
+
 endif
 
 
diff --git a/include/resolv.h b/include/resolv.h
index 3434f5d8c..6651dded9 100644
--- a/include/resolv.h
+++ b/include/resolv.h
@@ -101,53 +101,64 @@ typedef res_sendhookact (*res_send_rhook) (const struct sockaddr_in *ns,
 # define RES_DFLRETRY		2	/* Default #/tries. */
 # define RES_MAXTIME		65535	/* Infinity, in milliseconds. */
 
+/* _res (an instance of this structure) uses 0.5kb in bss
+ * in "ordinary" libc's (glibc, xBSD). We want to be less wasteful.
+ * We (1) shuffle and shrink some integer fields,
+ * and (2) can switch off stuff we don't support.
+ * Everything inside __UCLIBC_HAS_COMPAT_RES_STATE__
+ * is not actually used by uclibc and can be configured off.
+ * However, this will prevent some programs from building.
+ * Really obscure stuff with no observed users in the wild is under
+ * __UCLIBC_HAS_EXTRA_COMPAT_RES_STATE__.
+ * I guess it's safe to set that to N.
+ */
 struct __res_state {
-	int	retrans;	 	/* retransmition time interval */
+#ifdef __UCLIBC_HAS_COMPAT_RES_STATE__
+	int	retrans;	 	/* retransmission time interval */
 	int	retry;			/* number of times to retransmit */
-	u_long	options;		/* option flags - see below. */
-	int	nscount;		/* number of name servers */
+#endif
+	u_int32_t options;		/* (was: ulong) option flags - see below. */
 	struct sockaddr_in
 		nsaddr_list[MAXNS];	/* address of name server */
-# define nsaddr	nsaddr_list[0]		/* for backward compatibility */
-	u_short	id;			/* current message id */
+#define nsaddr nsaddr_list[0]		/* for backward compatibility */
 	char	*dnsrch[MAXDNSRCH+1];	/* components of domain to search */
+#ifdef __UCLIBC_HAS_COMPAT_RES_STATE__
+	/* googling for "_res.defdname" says it's still sometimes used.
+	 * Pity. It's huge, I want to move it to EXTRA_COMPAT... */
 	char	defdname[256];		/* default domain (deprecated) */
-	u_long	pfcode;			/* RES_PRF_ flags - see below. */
-	unsigned ndots:4;		/* threshold for initial abs. query */
-	unsigned nsort:4;		/* number of elements in sort_list[] */
-	char	unused[3];
+#endif
+	u_int8_t nscount;		/* (was: int) number of name servers */
+	u_int8_t ndots;			/* (was: unsigned:4) threshold for initial abs. query */
+#ifdef __UCLIBC_HAS_COMPAT_RES_STATE__
+	u_int8_t nsort;			/* (was: unsigned:4) number of elements in sort_list[] */
+	u_int16_t pfcode;		/* (was: ulong) RES_PRF_ flags. Used by dig. */
+	unsigned short id;		/* current message id */
+	int	res_h_errno;		/* last one set for this context */
 	struct {
 		struct in_addr	addr;
 		u_int32_t	mask;
 	} sort_list[MAXRESOLVSORT];
-	res_send_qhook qhook;		/* query hook */
-	res_send_rhook rhook;		/* response hook */
-	int	res_h_errno;		/* last one set for this context */
-	int	_vcsock;		/* PRIVATE: for res_send VC i/o */
-	u_int	_flags;			/* PRIVATE: see below */
 	union {
-		char	pad[52];	/* On an i386 this means 512b total. */
 		struct {
 			u_int16_t		nscount;
-#if 0
-			u_int16_t		nsmap[MAXNS];
-#else
 			u_int16_t		nstimes[MAXNS]; /* ms. */
-#endif
 			int			nssocks[MAXNS];
+			/* below: not in xBSD. glibc only? */
 			u_int16_t		nscount6;
 			u_int16_t		nsinit;
 			struct sockaddr_in6	*nsaddrs[MAXNS];
-#if 0
-#ifdef _LIBC
-			unsigned long long int	initstamp
-			  __attribute__((packed));
-#else
-			unsigned int		_initstamp[2];
-#endif
-#endif
 		} _ext;
 	} _u;
+#endif
+#ifdef __UCLIBC_HAS_EXTRA_COMPAT_RES_STATE__
+	/* Truly obscure stuff.
+	 * Googling for "_res.XXX" for these members
+	 * turned up basically empty */
+	res_send_qhook qhook;		/* query hook */
+	res_send_rhook rhook;		/* response hook */
+	int	_vcsock;		/* PRIVATE: for res_send VC i/o */
+	unsigned _flags;		/* PRIVATE: see below */
+#endif
 };
 
 typedef struct __res_state *res_state;
@@ -196,6 +207,7 @@ struct res_sym {
 
 /*
  * Resolver options (keep these in synch with res_debug.c, please)
+ * (which of these do we really implement??)
  */
 #define RES_INIT	0x00000001	/* address initialized */
 #define RES_DEBUG	0x00000002	/* print debug messages */
diff --git a/libc/inet/resolv.c b/libc/inet/resolv.c
index 7ef2fba45..b7ab27690 100644
--- a/libc/inet/resolv.c
+++ b/libc/inet/resolv.c
@@ -1255,20 +1255,26 @@ int res_init(void)
 	__UCLIBC_MUTEX_LOCK(__resolv_lock);	/* must be a recursive lock! */
 	__close_nameservers();
 	__open_nameservers();
+	memset(rp, 0, sizeof(*rp));
+	rp->options = RES_INIT;
+#ifdef __UCLIBC_HAS_COMPAT_RES_STATE__
 	rp->retrans = RES_TIMEOUT;
 	rp->retry = 4;
-	rp->options = RES_INIT;
-	rp->id = (u_int) random();
-	rp->nsaddr.sin_addr.s_addr = INADDR_ANY;
-	rp->nsaddr.sin_family = AF_INET;
-	rp->nsaddr.sin_port = htons(NAMESERVER_PORT);
+	rp->id = random();
+#endif
+	/* man resolv.conf says:
+	 * "On a normally configured system this file should not be necessary.
+	 * The only name server to be queried will be on the local machine;
+	 * the domain name is determined from the host name
+	 * and the domain search path is constructed from the domain name" */
+	rp->nscount = 1;
+	rp->nsaddr_list[0].sin_addr.s_addr = INADDR_ANY;
+	rp->nsaddr_list[0].sin_family = AF_INET;
+	rp->nsaddr_list[0].sin_port = htons(NAMESERVER_PORT);
 	rp->ndots = 1;
-	/** rp->pfcode = 0; **/
+#ifdef __UCLIBC_HAS_EXTRA_COMPAT_RES_STATE__
 	rp->_vcsock = -1;
-	/** rp->_flags = 0; **/
-	/** rp->qhook = NULL; **/
-	/** rp->rhook = NULL; **/
-	/** rp->_u._ext.nsinit = 0; **/
+#endif
 
 	if (__searchdomains) {
 		int i;
@@ -1286,8 +1292,8 @@ int res_init(void)
 				rp->nsaddr_list[i].sin_port = htons(NAMESERVER_PORT);
 			}
 		}
+		rp->nscount = __nameservers;
 	}
-	rp->nscount = __nameservers;
 	__UCLIBC_MUTEX_UNLOCK(__resolv_lock);
 
 	return 0;