Further void * / const fixes.

Yet more of these that commits 7babe66a8 and 8d882756b didn't spot. I
bet these still aren't the last, either.

misc.c

@@ -485,7 +485,7 @@ struct strbuf_impl {
     ((buf)->visible.s = (ptr),                                  \
      (buf)->visible.u = (unsigned char *)(buf)->visible.s)
 
-char *strbuf_append(strbuf *buf_o, size_t len)
+void *strbuf_append(strbuf *buf_o, size_t len)
 {
     struct strbuf_impl *buf = FROMFIELD(buf_o, struct strbuf_impl, visible);
     char *toret;

misc.h

@@ -40,7 +40,7 @@ struct strbuf {
 };
 strbuf *strbuf_new(void);
 void strbuf_free(strbuf *buf);
-char *strbuf_append(strbuf *buf, size_t len);
+void *strbuf_append(strbuf *buf, size_t len);
 char *strbuf_to_str(strbuf *buf); /* does free buf, but you must free result */
 void strbuf_catf(strbuf *buf, const char *fmt, ...);
 void strbuf_catfv(strbuf *buf, const char *fmt, va_list ap);

ssh.h

@@ -350,10 +350,10 @@ struct ssh_mac {
     /* Passes in the cipher context */
     void *(*make_context)(void *);
     void (*free_context)(void *);
-    void (*setkey) (void *, unsigned char *key);
+    void (*setkey) (void *, const void *key);
     /* whole-packet operations */
-    void (*generate) (void *, unsigned char *blk, int len, unsigned long seq);
+    void (*generate) (void *, void *blk, int len, unsigned long seq);
-    int (*verify) (void *, unsigned char *blk, int len, unsigned long seq);
+    int (*verify) (void *, const void *blk, int len, unsigned long seq);
     /* partial-packet operations */
     void (*start) (void *);
     BinarySink *(*sink) (void *);

sshccp.c

@@ -878,7 +878,7 @@ static void poly_free_context(void *ctx)
     /* Not allocated, just forwarded, no need to free */
 }
 
-static void poly_setkey(void *ctx, unsigned char *key)
+static void poly_setkey(void *ctx, const void *key)
 {
     /* Uses the same context as ChaCha20, so ignore */
 }
@@ -948,7 +948,8 @@ static int poly_verresult(void *handle, unsigned char const *blk)
 }
 
 /* The generic poly operation used before generate and verify */
-static void poly_op(void *handle, unsigned char *blk, int len, unsigned long seq)
+static void poly_op(void *handle, const unsigned char *blk, int len,
+                    unsigned long seq)
 {
     struct ccp_context *ctx = (struct ccp_context *)handle;
     poly_start(ctx);
@@ -957,14 +958,17 @@ static void poly_op(void *handle, unsigned char *blk, int len, unsigned long seq
     put_data(ctx, blk, len);
 }
 
-static void poly_generate(void *handle, unsigned char *blk, int len, unsigned long seq)
+static void poly_generate(void *handle, void *vblk, int len, unsigned long seq)
 {
+    unsigned char *blk = (unsigned char *)vblk;
     poly_op(handle, blk, len, seq);
     poly_genresult(handle, blk+len);
 }
 
-static int poly_verify(void *handle, unsigned char *blk, int len, unsigned long seq)
+static int poly_verify(void *handle, const void *vblk, int len,
+                       unsigned long seq)
 {
+    const unsigned char *blk = (const unsigned char *)vblk;
     poly_op(handle, blk, len, seq);
     return poly_verresult(handle, blk+len);
 }

sshmd5.c

@@ -261,7 +261,7 @@ void hmacmd5_key(void *handle, void const *keyv, int len)
     smemclr(foo, 64);		       /* burn the evidence */
 }
 
-static void hmacmd5_key_16(void *handle, unsigned char *key)
+static void hmacmd5_key_16(void *handle, const void *key)
 {
     hmacmd5_key(handle, key, 16);
 }
@@ -329,15 +329,17 @@ static void hmacmd5_do_hmac_ssh(void *handle, unsigned char const *blk, int len,
     hmacmd5_do_hmac_internal(handle, seqbuf, 4, blk, len, hmac);
 }
 
-static void hmacmd5_generate(void *handle, unsigned char *blk, int len,
+static void hmacmd5_generate(void *handle, void *vblk, int len,
 			     unsigned long seq)
 {
+    unsigned char *blk = (unsigned char *)vblk;
     hmacmd5_do_hmac_ssh(handle, blk, len, seq, blk + len);
 }
 
-static int hmacmd5_verify(void *handle, unsigned char *blk, int len,
+static int hmacmd5_verify(void *handle, const void *vblk, int len,
 			  unsigned long seq)
 {
+    const unsigned char *blk = (const unsigned char *)vblk;
     unsigned char correct[16];
     hmacmd5_do_hmac_ssh(handle, blk, len, seq, correct);
     return smemeq(correct, blk + len, 16);

sshsh256.c

@@ -267,7 +267,8 @@ static void sha256_free_context(void *handle)
     sfree(handle);
 }
 
-static void sha256_key_internal(void *handle, unsigned char *key, int len)
+static void sha256_key_internal(void *handle,
+                                const unsigned char *key, int len)
 {
     SHA256_State *keys = (SHA256_State *)handle;
     unsigned char foo[64];
@@ -288,7 +289,7 @@ static void sha256_key_internal(void *handle, unsigned char *key, int len)
     smemclr(foo, 64);		       /* burn the evidence */
 }
 
-static void sha256_key(void *handle, unsigned char *key)
+static void sha256_key(void *handle, const void *key)
 {
     sha256_key_internal(handle, key, 32);
 }
@@ -322,7 +323,7 @@ static void hmacsha256_genresult(void *handle, unsigned char *hmac)
     SHA256_Final(&s, hmac);
 }
 
-static void sha256_do_hmac(void *handle, unsigned char *blk, int len,
+static void sha256_do_hmac(void *handle, const unsigned char *blk, int len,
 			 unsigned long seq, unsigned char *hmac)
 {
     BinarySink *bs = hmacsha256_sink(handle);
@@ -332,9 +333,10 @@ static void sha256_do_hmac(void *handle, unsigned char *blk, int len,
     hmacsha256_genresult(handle, hmac);
 }
 
-static void sha256_generate(void *handle, unsigned char *blk, int len,
+static void sha256_generate(void *handle, void *vblk, int len,
 			  unsigned long seq)
 {
+    unsigned char *blk = (unsigned char *)vblk;
     sha256_do_hmac(handle, blk, len, seq, blk + len);
 }
 
@@ -345,9 +347,10 @@ static int hmacsha256_verresult(void *handle, unsigned char const *hmac)
     return smemeq(correct, hmac, 32);
 }
 
-static int sha256_verify(void *handle, unsigned char *blk, int len,
+static int sha256_verify(void *handle, const void *vblk, int len,
 		       unsigned long seq)
 {
+    const unsigned char *blk = (const unsigned char *)vblk;
     unsigned char correct[32];
     sha256_do_hmac(handle, blk, len, seq, correct);
     return smemeq(correct, blk + len, 32);

sshsha.c

@@ -294,7 +294,7 @@ static void sha1_free_context(void *handle)
     sfree(handle);
 }
 
-static void sha1_key_internal(void *handle, unsigned char *key, int len)
+static void sha1_key_internal(void *handle, const unsigned char *key, int len)
 {
     SHA_State *keys = (SHA_State *)handle;
     unsigned char foo[64];
@@ -315,12 +315,12 @@ static void sha1_key_internal(void *handle, unsigned char *key, int len)
     smemclr(foo, 64);		       /* burn the evidence */
 }
 
-static void sha1_key(void *handle, unsigned char *key)
+static void sha1_key(void *handle, const void *key)
 {
     sha1_key_internal(handle, key, 20);
 }
 
-static void sha1_key_buggy(void *handle, unsigned char *key)
+static void sha1_key_buggy(void *handle, const void *key)
 {
     sha1_key_internal(handle, key, 16);
 }
@@ -354,7 +354,7 @@ static void hmacsha1_genresult(void *handle, unsigned char *hmac)
     SHA_Final(&s, hmac);
 }
 
-static void sha1_do_hmac(void *handle, unsigned char *blk, int len,
+static void sha1_do_hmac(void *handle, const unsigned char *blk, int len,
 			 unsigned long seq, unsigned char *hmac)
 {
     BinarySink *bs = hmacsha1_sink(handle);
@@ -364,9 +364,10 @@ static void sha1_do_hmac(void *handle, unsigned char *blk, int len,
     hmacsha1_genresult(handle, hmac);
 }
 
-static void sha1_generate(void *handle, unsigned char *blk, int len,
+static void sha1_generate(void *handle, void *vblk, int len,
 			  unsigned long seq)
 {
+    unsigned char *blk = (unsigned char *)vblk;
     sha1_do_hmac(handle, blk, len, seq, blk + len);
 }
 
@@ -377,9 +378,10 @@ static int hmacsha1_verresult(void *handle, unsigned char const *hmac)
     return smemeq(correct, hmac, 20);
 }
 
-static int sha1_verify(void *handle, unsigned char *blk, int len,
+static int sha1_verify(void *handle, const void *vblk, int len,
 		       unsigned long seq)
 {
+    const unsigned char *blk = (const unsigned char *)vblk;
     unsigned char correct[20];
     sha1_do_hmac(handle, blk, len, seq, correct);
     return smemeq(correct, blk + len, 20);
@@ -392,9 +394,10 @@ static void hmacsha1_96_genresult(void *handle, unsigned char *hmac)
     memcpy(hmac, full, 12);
 }
 
-static void sha1_96_generate(void *handle, unsigned char *blk, int len,
+static void sha1_96_generate(void *handle, void *vblk, int len,
 			     unsigned long seq)
 {
+    unsigned char *blk = (unsigned char *)vblk;
     unsigned char full[20];
     sha1_do_hmac(handle, blk, len, seq, full);
     memcpy(blk + len, full, 12);
@@ -407,9 +410,10 @@ static int hmacsha1_96_verresult(void *handle, unsigned char const *hmac)
     return smemeq(correct, hmac, 12);
 }
 
-static int sha1_96_verify(void *handle, unsigned char *blk, int len,
+static int sha1_96_verify(void *handle, const void *vblk, int len,
 		       unsigned long seq)
 {
+    const unsigned char *blk = (const unsigned char *)vblk;
     unsigned char correct[20];
     sha1_do_hmac(handle, blk, len, seq, correct);
     return smemeq(correct, blk + len, 12);