better error messages. Helps with #4219

diff --git a/src/modules/rlm_smsotp/rlm_smsotp.c b/src/modules/rlm_smsotp/rlm_smsotp.c
index 1d7d1d2f75e6f02e39f88bc3254c024a5c8107d6..409ff0b8019ba03faeb797e7317911ea916c7238 100644 (file)
--- a/src/modules/rlm_smsotp/rlm_smsotp.c
+++ b/src/modules/rlm_smsotp/rlm_smsotp.c
@@ -199,8 +199,12 @@ static rlm_rcode_t CC_HINT(nonnull) mod_authenticate(void *instance, REQUEST *re
 
        /* Get greeting */
        bufsize = read_all(fdp, buffer, sizeof(buffer));
-       if (bufsize <= 0) {
-               REDEBUG("Failed reading from socket");
+       if (bufsize == 0) {
+               REDEBUG("No data available from socket - other end closed the connection");
+               goto done;
+       }
+       if (bufsize < 0) {
+               REDEBUG("Failed reading from socket: %s", fr_syserror(errno));
                goto done;
        }