zlib: Move conditional compilation inside of the gzip.c

This implements stub for the compression functions and includes the
gzip.c in the compilation target uncoditionally, keeping the WITH_ZLIB
conditional compilation only in the gzip.c

Signed-off-by: Jakub Jelen <jjelen@redhat.com>
Reviewed-by: Andreas Schneider <asn@cryptomilk.org>

src/CMakeLists.txt

@@ -91,6 +91,7 @@ set(libssh_SRCS
   ecdh.c
   error.c
   getpass.c
+  gzip.c
   init.c
   kdf.c
   kex.c
@@ -252,13 +253,6 @@ if (WITH_GEX)
   )
 endif (WITH_GEX)
 
-if (WITH_ZLIB)
-  set(libssh_SRCS
-    ${libssh_SRCS}
-    gzip.c
-  )
-endif(WITH_ZLIB)
-
 if (WITH_GSSAPI AND GSSAPI_FOUND)
   set(libssh_SRCS
     ${libssh_SRCS}

src/gzip.c

@@ -26,13 +26,15 @@
 
 #include <stdlib.h>
 #include <string.h>
-#include <zlib.h>
 
 #include "libssh/buffer.h"
 #include "libssh/crypto.h"
 #include "libssh/priv.h"
 #include "libssh/session.h"
 
+#ifdef WITH_ZLIB
+#include <zlib.h>
+
 #ifndef BLOCKSIZE
 #define BLOCKSIZE 4092
 #endif
@@ -274,3 +276,27 @@ compress_cleanup(struct ssh_crypto_struct *crypto)
     }
     SAFE_FREE(crypto->compress_in_ctx);
 }
+#else /* WITH_ZLIB */
+
+int
+compress_buffer(UNUSED_PARAM(ssh_session session), UNUSED_PARAM(ssh_buffer buf))
+{
+    /* without zlib compiled in, this should never happen */
+    return -1;
+}
+int
+decompress_buffer(UNUSED_PARAM(ssh_session session),
+                  UNUSED_PARAM(ssh_buffer buf),
+                  UNUSED_PARAM(size_t maxlen))
+{
+    /* without zlib compiled in, this should never happen */
+    return -1;
+}
+
+void
+compress_cleanup(UNUSED_PARAM(struct ssh_crypto_struct *crypto))
+{
+    /* no-op */
+}
+
+#endif /* WITH_ZLIB */

src/packet.c

@@ -1303,7 +1303,6 @@ ssh_packet_socket_callback(const void *data, size_t receivedlen, void *user)
             ssh_buffer_pass_bytes_end(session->in_buffer, padding);
             compsize = ssh_buffer_get_len(session->in_buffer);
 
-#ifdef WITH_ZLIB
             if (crypto && crypto->do_compress_in &&
                 ssh_buffer_get_len(session->in_buffer) > 0) {
                 rc = decompress_buffer(session, session->in_buffer,
@@ -1312,7 +1311,6 @@ ssh_packet_socket_callback(const void *data, size_t receivedlen, void *user)
                     goto error;
                 }
             }
-#endif /* WITH_ZLIB */
             payloadsize = ssh_buffer_get_len(session->in_buffer);
             if (session->recv_seq == UINT32_MAX) {
                 /* Overflowing sequence numbers is always fishy */
@@ -1706,7 +1704,6 @@ static int packet_send2(ssh_session session)
         lenfield_blocksize = 0;
     }
 
-#ifdef WITH_ZLIB
     if (crypto != NULL && crypto->do_compress_out &&
         ssh_buffer_get_len(session->out_buffer) > 0) {
         rc = compress_buffer(session,session->out_buffer);
@@ -1715,7 +1712,6 @@ static int packet_send2(ssh_session session)
         }
         currentlen = ssh_buffer_get_len(session->out_buffer);
     }
-#endif /* WITH_ZLIB */
     compsize = currentlen;
     /* compressed payload + packet len (4) + padding_size len (1) */
     /* totallen - lenfield_blocksize - etm_packet_offset must be equal to 0 (mod blocksize) */

src/wrapper.c

@@ -197,9 +197,7 @@ void crypto_free(struct ssh_crypto_struct *crypto)
         explicit_bzero(crypto->secret_hash, crypto->digest_len);
         SAFE_FREE(crypto->secret_hash);
     }
-#ifdef WITH_ZLIB
     compress_cleanup(crypto);
-#endif /* WITH_ZLIB */
     SAFE_FREE(crypto->encryptIV);
     SAFE_FREE(crypto->decryptIV);
     SAFE_FREE(crypto->encryptMAC);