Make pointers to data that is not modified const. (#2117)

This allow to pass constrant string i particular and constant data in general
to nng functions.

Co-authored-by: Garrett D'Amore <garrett@damore.org>

1 files changed, 1 insertions, 1 deletions

diff --git a/src/nng.c b/src/nng.c
index 68820675..58b1f25c 100644
--- a/src/nng.c
+++ b/src/nng.c
@@ -124,7 +124,7 @@ nng_recvmsg(nng_socket s, nng_msg **msgp, int flags)
 }
 
 int
-nng_send(nng_socket s, void *buf, size_t len, int flags)
+nng_send(nng_socket s, const void *buf, size_t len, int flags)
 {
 	nng_msg *msg;
 	int      rv;