non-modified payload arguments are pointer-to-const

The payload parameters to nfq_set_verdict(), nfq_set_verdict2(), and
nfq_set_verdict_mark() are not modified by those functions, and
therefore should have datatype pointer-to-const.  This both causes the
source-code to more effectively represent what is the purpose of the
parameter, and eliminates the need to cast away const-ness when calling
the functions with compilers that enforce strict casting.  All existing
calling code should not need modification as pointer-to-X automatically
converts to pointer-to-const-X.

Signed-off-by: David Favro <netfilter@meta-dynamic.com>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

diff --git a/include/libnetfilter_queue/libnetfilter_queue.h b/include/libnetfilter_queue/libnetfilter_queue.h
index 88a9b8c..2e2ca8b 100644 (file)
--- a/include/libnetfilter_queue/libnetfilter_queue.h
+++ b/include/libnetfilter_queue/libnetfilter_queue.h
@@ -60,14 +60,14 @@ extern int nfq_set_verdict(struct nfq_q_handle *qh,
                             u_int32_t id,
                             u_int32_t verdict,
                             u_int32_t data_len,
-                            unsigned char *buf);
+                            const unsigned char *buf);
 
 extern int nfq_set_verdict2(struct nfq_q_handle *qh,
                            u_int32_t id,
                            u_int32_t verdict, 
                            u_int32_t mark,
                            u_int32_t datalen,
-                           unsigned char *buf);
+                           const unsigned char *buf);
 
 extern __attribute__((deprecated))
 int nfq_set_verdict_mark(struct nfq_q_handle *qh, 
@@ -75,7 +75,7 @@ int nfq_set_verdict_mark(struct nfq_q_handle *qh,
                         u_int32_t verdict, 
                         u_int32_t mark,
                         u_int32_t datalen,
-                        unsigned char *buf);
+                        const unsigned char *buf);
 
 /* message parsing function */
 

diff --git a/src/libnetfilter_queue.c b/src/libnetfilter_queue.c
index cc19e6a..4cc4925 100644 (file)
--- a/src/libnetfilter_queue.c
+++ b/src/libnetfilter_queue.c
@@ -610,7 +610,7 @@ int nfq_set_queue_maxlen(struct nfq_q_handle *qh,
 
 static int __set_verdict(struct nfq_q_handle *qh, u_int32_t id,
                u_int32_t verdict, u_int32_t mark, int set_mark,
-               u_int32_t data_len, unsigned char *data)
+               u_int32_t data_len, const unsigned char *data)
 {
        struct nfqnl_msg_verdict_hdr vh;
        union {
@@ -646,8 +646,9 @@ static int __set_verdict(struct nfq_q_handle *qh, u_int32_t id,
        nvecs = 1;
 
        if (data_len) {
+               /* The typecast here is to cast away data's const-ness: */
                nfnl_build_nfa_iovec(&iov[1], &data_attr, NFQA_PAYLOAD,
-                               data_len, data);
+                               data_len, (unsigned char *) data);
                nvecs += 2;
                /* Add the length of the appended data to the message
                 * header.  The size of the attribute is given in the
@@ -688,7 +689,7 @@ static int __set_verdict(struct nfq_q_handle *qh, u_int32_t id,
  */
 int nfq_set_verdict(struct nfq_q_handle *qh, u_int32_t id,
                u_int32_t verdict, u_int32_t data_len, 
-               unsigned char *buf)
+               const unsigned char *buf)
 {
        return __set_verdict(qh, id, verdict, 0, 0, data_len, buf);
 }      
@@ -704,7 +705,7 @@ int nfq_set_verdict(struct nfq_q_handle *qh, u_int32_t id,
  */
 int nfq_set_verdict2(struct nfq_q_handle *qh, u_int32_t id,
                     u_int32_t verdict, u_int32_t mark,
-                    u_int32_t data_len, unsigned char *buf)
+                    u_int32_t data_len, const unsigned char *buf)
 {
        return __set_verdict(qh, id, verdict, htonl(mark), 1, data_len, buf);
 }
@@ -725,7 +726,7 @@ int nfq_set_verdict2(struct nfq_q_handle *qh, u_int32_t id,
  */
 int nfq_set_verdict_mark(struct nfq_q_handle *qh, u_int32_t id,
                u_int32_t verdict, u_int32_t mark,
-               u_int32_t data_len, unsigned char *buf)
+               u_int32_t data_len, const unsigned char *buf)
 {
        return __set_verdict(qh, id, verdict, mark, 1, data_len, buf);
 }