Queisce two category of clang warnings:

1.  missing explicit includes for string.h, stdio.h, etc
2.  missing explicit declaration for some common functions

I have been unable to contact the upstream maintainer for this patch,
http://www.inner.net/opie appears to be the source of truth but it
unreachable

contrib/opie/libopie/accessfile.c

@@ -28,6 +28,7 @@ License Agreement applies to this software.
 #include "opie_cfg.h"
 
 #include <stdio.h>
+#include <ctype.h>
 #include <sys/types.h>
 #include <sys/socket.h>
 #include <netinet/in.h>

contrib/opie/libopie/generator.c

@@ -49,6 +49,7 @@ $FreeBSD$
 #if DEBUG
 #include <syslog.h>
 #endif /* DEBUG */
+#include <stdio.h>
 #include "opie.h"
 
 static char *algids[] = { NULL, NULL, NULL, "sha1", "md4", "md5" };

contrib/opie/libopie/lookup.c

@@ -13,6 +13,7 @@ you didn't get a copy, you may request one from <license@inner.net>.
 
 #include "opie_cfg.h"
 #include <stdio.h>
+#include <string.h>
 #include "opie.h"
 
 int opielookup FUNCTION((opie, principal), struct opie *opie AND char *principal)

contrib/opie/libopie/newseed.c

@@ -18,6 +18,9 @@ $FreeBSD$
 */
 
 #include "opie_cfg.h"
+#ifndef HAVE_TIME_H
+#define HAVE_TIME_H 1
+#endif
 #if HAVE_TIME_H
 #include <time.h>
 #endif /* HAVE_TIME_H */
@@ -35,6 +38,8 @@ $FreeBSD$
 #if DEBUG
 #include <syslog.h>
 #endif /* DEBUG */
+#include <stdio.h>
+#include <stdlib.h>
 #include "opie.h"
 
 int opienewseed FUNCTION((seed), char *seed)

contrib/opie/libopie/parsechallenge.c

@@ -19,6 +19,8 @@ you didn't get a copy, you may request one from <license@inner.net>.
 #if HAVE_STRING_H
 #include <string.h>
 #endif /* HAVE_STRING_H */
+#include <ctype.h>
+#include <stdlib.h>
 #include "opie.h"
 
 struct algorithm {

contrib/opie/libopie/passwd.c

@@ -20,6 +20,7 @@ you didn't get a copy, you may request one from <license@inner.net>.
 	Created by cmetz for OPIE 2.22.
 */
 
+#include <string.h>
 #include "opie_cfg.h"
 #include "opie.h"
 

contrib/opie/libopie/randomchallenge.c

@@ -26,6 +26,9 @@ License Agreement applies to this software.
         Created at NRL for OPIE 2.2 from opiesubr2.c
 */
 
+#include <stdio.h>
+#include <string.h>
+#include <stdlib.h>
 #include "opie_cfg.h"
 #include "opie.h"
 

contrib/opie/libopie/verify.c

@@ -24,6 +24,7 @@ you didn't get a copy, you may request one from <license@inner.net>.
 #ifdef HAVE_STRING_H
 #include <string.h>
 #endif /* HAVE_STRING_H */
+#include <ctype.h>
 #include "opie.h"
 
 #define RESPONSE_STANDARD  0

contrib/opie/libopie/version.c

@@ -17,6 +17,8 @@ License Agreement applies to this software.
 	Modified by cmetz for OPIE 2.2. Use FUNCTION declaration et al.
         Created at NRL for OPIE 2.2 from opiesubr.c.
 */
+#include <stdio.h>
+#include <stdlib.h>
 #include "opie_cfg.h"
 #include "opie.h"
 

contrib/opie/opie.h

@@ -128,6 +128,7 @@ void opieunlockaeh __P((void));
 void opiedisableaeh __P((void));
 int  opielookup __P((struct opie *,char *));
 int  opiepasscheck __P((char *));
+int opienewseed __P((char *));
 void opierandomchallenge __P((char *));
 char * opieskipspace __P((register char *));
 void opiestripcrlf __P((char *));
@@ -139,6 +140,8 @@ const char *opie_get_algorithm __P((void));
 int  opie_haskey __P((char *username));
 char *opie_keyinfo __P((char *));
 int  opie_passverify __P((char *username, char *passwd));
+int opieinsecure __P((void));
+void opieversion __P((void));
 __END_DECLS
 
 #if _OPIE
@@ -158,6 +161,7 @@ FILE *__opieopen __P((char *, int, int));
 int __opiereadrec __P((struct opie *));
 int __opiewriterec __P((struct opie *));
 int __opieparsechallenge __P((char *buffer, int *algorithm, int *sequence, char **seed, int *exts));
+VOIDRET opiehashlen __P((int algorithm, VOIDPTR in, struct opie_otpkey *out, int n));
 __END_DECLS
 
 #define opiestrncpy(dst, src, n) \

contrib/opie/opieinfo.c

@@ -38,6 +38,7 @@ $FreeBSD$
 #include <sys/param.h>
 #include <errno.h>
 #include <stdio.h>
+#include <stdlib.h>
 #include <string.h>
 #if HAVE_UNISTD_H
 #include <unistd.h>

contrib/opie/opiekey.c

@@ -45,6 +45,7 @@ $FreeBSD$
 #include <stdio.h>
 #include <string.h>
 #include <stdlib.h>
+#include <unistd.h>
 
 #include "opie.h"