Fix protocol error (#1106)

Fix ProtocolError

This commit attempts to fix hiredis such that a recoverable write error
will be retried rather than throwing a hard error.

Since our read/write functions are now behind function pointers, we
specify semantically that a return value of < 0 is a hard error, 0 a
recoverable error, and > 0 a success.

Our default `redisNetRead` function was already doing something similar
so this also improves code consistency.

Resolves #961

Co-authored-by: Maksim Tuleika <maksim.tuleika@appcast.io>

1 files changed, 8 insertions, 4 deletions

diff --git a/net.c b/net.c
index 2b591b9..0f36da2 100644
--- a/net.c
+++ b/net.c
@@ -70,7 +70,7 @@ ssize_t redisNetRead(redisContext *c, char *buf, size_t bufcap) {
             __redisSetError(c, REDIS_ERR_TIMEOUT, "recv timeout");
             return -1;
         } else {
-            __redisSetError(c, REDIS_ERR_IO, NULL);
+            __redisSetError(c, REDIS_ERR_IO, strerror(errno));
             return -1;
         }
     } else if (nread == 0) {
@@ -82,15 +82,19 @@ ssize_t redisNetRead(redisContext *c, char *buf, size_t bufcap) {
 }
 
 ssize_t redisNetWrite(redisContext *c) {
-    ssize_t nwritten = send(c->fd, c->obuf, sdslen(c->obuf), 0);
+    ssize_t nwritten;
+
+    nwritten = send(c->fd, c->obuf, sdslen(c->obuf), 0);
     if (nwritten < 0) {
         if ((errno == EWOULDBLOCK && !(c->flags & REDIS_BLOCK)) || (errno == EINTR)) {
-            /* Try again later */
+            /* Try again */
+            return 0;
         } else {
-            __redisSetError(c, REDIS_ERR_IO, NULL);
+            __redisSetError(c, REDIS_ERR_IO, strerror(errno));
             return -1;
         }
     }
+
     return nwritten;
 }