para_client: Fix unreliable uses of FD_ISSET().

The client_recv_buffer() function of client_common.c did not
check for EAGAIN. Use the new nonblock API if possible that
gets things just right and add a check for EAGAIN for RC4
encrypted connections.

diff --git a/client_common.c b/client_common.c
index f34f81bfc3b4aecc8cd4bdba5631e30116e4a352..593cb2c044c37995d76fa58f4abcb0a6ab198668 100644 (file)
--- a/client_common.c
+++ b/client_common.c
@@ -107,17 +107,29 @@ static void client_pre_select(struct sched *s, struct task *t)
        }
 }
 
-static ssize_t client_recv_buffer(struct client_task *ct, char *buf, size_t len)
+static int client_recv_buffer(struct client_task *ct, fd_set *rfds,
+               char *buf, size_t sz, size_t *n)
 {
-       ssize_t ret;
+       int ret;
 
        if (ct->status < CL_SENT_CH_RESPONSE)
-               ret = recv_buffer(ct->rc4c.fd, buf, len);
-       else
-               ret = rc4_recv_buffer(&ct->rc4c, buf, len);
+               return read_nonblock(ct->rc4c.fd, buf, sz, rfds, n);
+
+       *n = 0;
+       ret = rc4_recv_buffer(&ct->rc4c, buf, sz);
+       /*
+        * rc4_recv_buffer is used with blocking fds elsewhere, so it
+        * does not use the nonblock-API. Therefore we need to
+        * check for EOF and EAGAIN.
+        */
        if (ret == 0)
                return -E_SERVER_EOF;
-       return ret;
+       if (ret == -ERRNO_TO_PARA_ERROR(EAGAIN))
+               return 0;
+       if (ret < 0)
+               return ret;
+       *n = ret;
+       return 0;
 }
 
 /**
@@ -138,6 +150,7 @@ static void client_post_select(struct sched *s, struct task *t)
        struct client_task *ct = container_of(t, struct client_task, task);
        struct btr_node *btrn = ct->btrn;
        int ret = 0;
+       size_t n;
        char buf[CLIENT_BUFSIZE];
 
        t->error = 0;
@@ -145,11 +158,9 @@ static void client_post_select(struct sched *s, struct task *t)
                return;
        switch (ct->status) {
        case CL_CONNECTED: /* receive welcome message */
-               if (!FD_ISSET(ct->rc4c.fd, &s->rfds))
-                       return;
-               ret = client_recv_buffer(ct, buf, sizeof(buf));
-               if (ret < 0)
-                       goto err;
+               ret = client_recv_buffer(ct, &s->rfds, buf, sizeof(buf), &n);
+               if (ret < 0 || n == 0)
+                       goto out;
                ct->status = CL_RECEIVED_WELCOME;
                return;
        case CL_RECEIVED_WELCOME: /* send auth command */
@@ -173,14 +184,12 @@ static void client_post_select(struct sched *s, struct task *t)
                /* the SHA1 of the decrypted challenge */
                unsigned char challenge_sha1[HASH_SIZE];
 
-               if (!FD_ISSET(ct->rc4c.fd, &s->rfds))
-                       return;
-               ret = client_recv_buffer(ct, buf, sizeof(buf));
-               if (ret < 0)
-                       goto err;
-               PARA_INFO_LOG("<-- [challenge] (%d bytes)\n", ret);
+               ret = client_recv_buffer(ct, &s->rfds, buf, sizeof(buf), &n);
+               if (ret < 0 || n == 0)
+                       goto out;
+               PARA_INFO_LOG("<-- [challenge] (%zu bytes)\n", n);
                ret = para_decrypt_buffer(ct->key_file, crypt_buf,
-                       (unsigned char *)buf, ret);
+                       (unsigned char *)buf, n);
                if (ret < 0)
                        goto err;
                sha1_hash((char *)crypt_buf, CHALLENGE_SIZE, challenge_sha1);
@@ -199,19 +208,15 @@ static void client_post_select(struct sched *s, struct task *t)
                }
        case CL_SENT_CH_RESPONSE: /* read server response */
                {
-               size_t bytes_received;
-               if (!FD_ISSET(ct->rc4c.fd, &s->rfds))
-                       return;
-               ret = client_recv_buffer(ct, buf, sizeof(buf));
-               if (ret < 0)
-                       goto err;
-               bytes_received = ret;
+               ret = client_recv_buffer(ct, &s->rfds, buf, sizeof(buf), &n);
+               if (ret < 0 || n == 0)
+                       goto out;
                /* check if server has sent "Proceed" message */
                ret = -E_CLIENT_AUTH;
-               if (bytes_received < PROCEED_MSG_LEN)
-                       goto err;
+               if (n < PROCEED_MSG_LEN)
+                       goto out;
                if (!strstr(buf, PROCEED_MSG))
-                       goto err;
+                       goto out;
                ct->status = CL_RECEIVED_PROCEED;
                return;
                }
@@ -239,23 +244,20 @@ static void client_post_select(struct sched *s, struct task *t)
        case CL_SENT_COMMAND:
                {
                char *buf2;
-               if (!FD_ISSET(ct->rc4c.fd, &s->rfds))
-                       return;
                /* can not use "buf" here because we need a malloced buffer */
                buf2 = para_malloc(CLIENT_BUFSIZE);
-               ret = client_recv_buffer(ct, buf2, CLIENT_BUFSIZE);
-               if (ret < 0) {
+               ret = client_recv_buffer(ct, &s->rfds, buf2, CLIENT_BUFSIZE, &n);
+               if (n > 0) {
+                       if (strstr(buf2, AWAITING_DATA_MSG)) {
+                               free(buf2);
+                               ct->status = CL_SENDING;
+                               return;
+                       }
+                       ct->status = CL_RECEIVING;
+                       btr_add_output(buf2, n, btrn);
+               } else
                        free(buf2);
-                       goto err;
-               }
-               if (strstr(buf2, AWAITING_DATA_MSG)) {
-                       free(buf2);
-                       ct->status = CL_SENDING;
-                       return;
-               }
-               ct->status = CL_RECEIVING;
-               btr_add_output(buf2, ret, btrn);
-               return;
+               goto out;
                }
        case CL_SENDING:
                {
@@ -283,20 +285,24 @@ static void client_post_select(struct sched *s, struct task *t)
                        goto err;
                if (ret == 0)
                        return;
+               /*
+                * The FD_ISSET() is not strictly necessary, but is allows us
+                * to skip the malloc below if there is nothing to read anyway.
+                */
                if (!FD_ISSET(ct->rc4c.fd, &s->rfds))
                        return;
                buf2 = para_malloc(CLIENT_BUFSIZE);
-               ret = client_recv_buffer(ct, buf2, CLIENT_BUFSIZE);
-               if (ret < 0) {
+               ret = client_recv_buffer(ct, &s->rfds, buf2, CLIENT_BUFSIZE, &n);
+               if (n > 0) {
+                       buf2 = para_realloc(buf2, n);
+                       btr_add_output(buf2, n, btrn);
+               } else
                        free(buf2);
-                       goto err;
-               }
-               buf2 = para_realloc(buf2, ret);
-               btr_add_output(buf2, ret, btrn);
-               return;
+               goto out;
                }
        }
 err:
+out:
        t->error = ret;
        if (ret < 0) {
                if (ret != -E_SERVER_EOF && ret != -E_BTR_EOF)