libc/resolv: get rid of MD5

MD5 is used by libc/resolv to generate a random sequence id from a current time stamp. Replace this convoluted mechanism with a call to arc4random(). This permits us to entirely drop MD5 from libc, simplifying the MD5 rework proposed in D45670. Approved by:	markj Reviewed by:	kevans, markj See also:	D45670 Event:	EuroBSDcon 2025 Differential Revision:https://reviews.freebsd.org/D52784 

5 files changed, 6 insertions, 61 deletions

diff --git a/lib/libc/Makefile b/lib/libc/Makefile
index d0c254e33396..8705568f6d34 100644
--- a/lib/libc/Makefile
+++ b/lib/libc/Makefile
@@ -109,7 +109,6 @@ NOASM=
 .include "${LIBC_SRCTOP}/inet/Makefile.inc"
 .include "${LIBC_SRCTOP}/isc/Makefile.inc"
 .include "${LIBC_SRCTOP}/locale/Makefile.inc"
-.include "${LIBC_SRCTOP}/md/Makefile.inc"
 .include "${LIBC_SRCTOP}/nameser/Makefile.inc"
 .include "${LIBC_SRCTOP}/net/Makefile.inc"
 .include "${LIBC_SRCTOP}/nls/Makefile.inc"
diff --git a/lib/libc/include/port_before.h b/lib/libc/include/port_before.h
index cfc43c53f157..aa2cd394104a 100644
--- a/lib/libc/include/port_before.h
+++ b/lib/libc/include/port_before.h
@@ -5,7 +5,6 @@
 #define _LIBC	1
 #define DO_PTHREADS	1
 #define USE_POLL	1
-#define HAVE_MD5	1
 
 #define ISC_SOCKLEN_T	socklen_t
 #define ISC_FORMAT_PRINTF(fmt, args) \
diff --git a/lib/libc/md/Makefile.inc b/lib/libc/md/Makefile.inc
deleted file mode 100644
index 82c5f0670485..000000000000
--- a/lib/libc/md/Makefile.inc
+++ /dev/null
@@ -1,3 +0,0 @@
-.PATH: ${SRCTOP}/sys/kern
-
-SRCS+=	md5c.c
diff --git a/lib/libc/resolv/Symbol.map b/lib/libc/resolv/Symbol.map
index 6b9c43298fb5..26daecbe2eff 100644
--- a/lib/libc/resolv/Symbol.map
+++ b/lib/libc/resolv/Symbol.map
@@ -103,6 +103,5 @@ FBSD_1.0 {
 };
 
 FBSD_1.4 {
-	__res_rndinit;
	__res_nrandomid;
 };
diff --git a/lib/libc/resolv/res_init.c b/lib/libc/resolv/res_init.c
index 71ab2dcb7038..5a2fce013c8c 100644
--- a/lib/libc/resolv/res_init.c
+++ b/lib/libc/resolv/res_init.c
@@ -86,19 +86,6 @@
 #include <unistd.h>
 #include <netdb.h>
 
-#ifndef HAVE_MD5
-# include "../dst/md5.h"
-#else
-# ifdef SOLARIS2
-# include <sys/md5.h>
-# elif _LIBC
-# include <md5.h>
-# endif
-#endif
-#ifndef _MD5_H_
-# define _MD5_H_ 1	/*%< make sure we do not include rsaref md5.h file */
-#endif
-
 #include "un-namespace.h"
 
 #include "port_after.h"
@@ -184,8 +171,6 @@ __res_vinit(res_state statp, int preinit) {
	statp->options = RES_DEFAULT;
	}
 
-	statp->_rnd = malloc(16);
-	res_rndinit(statp);
	statp->id = res_nrandomid(statp);
 
	memset(u, 0, sizeof(u));
@@ -733,48 +718,18 @@ net_mask(struct in_addr in)	/*!< XXX - should really use system's version of th
 }
 #endif
 
-static u_char srnd[16];
-
 void
-res_rndinit(res_state statp)
+freebsd15_res_rndinit(res_state statp)
 {
-	struct timeval now;
-	u_int32_t u32;
-	u_int16_t u16;
-	u_char *rnd = statp->_rnd == NULL ? srnd : statp->_rnd;
-
-	gettimeofday(&now, NULL);
-	u32 = now.tv_sec;
-	memcpy(rnd, &u32, 4);
-	u32 = now.tv_usec;
-	memcpy(rnd + 4, &u32, 4);
-	u32 += now.tv_sec;
-	memcpy(rnd + 8, &u32, 4);
-	u16 = getpid();
-	memcpy(rnd + 12, &u16, 2);
+	(void)statp;
 }
+__sym_compat(__res_rndinit, freebsd15_res_rndinit, FBSD_1.4);
 
 u_int
 res_nrandomid(res_state statp) {
-	struct timeval now;
-	u_int16_t u16;
-	MD5_CTX ctx;
-	u_char *rnd = statp->_rnd == NULL ? srnd : statp->_rnd;
-
-	gettimeofday(&now, NULL);
-	u16 = (u_int16_t) (now.tv_sec ^ now.tv_usec);
-	memcpy(rnd + 14, &u16, 2);
-#ifndef HAVE_MD5
-	MD5_Init(&ctx);
-	MD5_Update(&ctx, rnd, 16);
-	MD5_Final(rnd, &ctx);
-#else
-	MD5Init(&ctx);
-	MD5Update(&ctx, rnd, 16);
-	MD5Final(rnd, &ctx);
-#endif
-	memcpy(&u16, rnd + 14, 2);
-	return ((u_int) u16);
+	(void) statp;
+
+	return ((u_int)(arc4random() & 0xffff));
 }
 
 /*%
@@ -808,10 +763,6 @@ res_ndestroy(res_state statp) {
	free(statp->_u._ext.ext);
	statp->_u._ext.ext = NULL;
	}
-	if (statp->_rnd != NULL) {
-	free(statp->_rnd);
-	statp->_rnd = NULL;
-	}
	statp->options &= ~RES_INIT;
 }