diff --git a/src/csocket.c b/src/csocket.c
index e88ee5d..fca14cc 100644
--- a/src/csocket.c
+++ b/src/csocket.c
@@ -16,17 +16,15 @@
 #include <sys/select.h>
 
 typedef struct f2b_conn_t {
-  int sock;
-  const char *path;
   f2b_buf_t recv;
   f2b_buf_t send;
+  int sock;
 } f2b_conn_t;
 
 struct f2b_csock_t {
   f2b_conn_t *clients[MAXCONNS];
   const char *path;
   int sock;
-  bool shutdown;
 };
 
 /* helpers */
@@ -60,6 +58,67 @@ f2b_conn_destroy(f2b_conn_t *conn) {
   free(conn);
 }
 
+int
+f2b_conn_process(f2b_conn_t *conn, bool in, void (*cb)(const f2b_cmd_t *cmd, f2b_buf_t *res)) {
+  f2b_cmd_t *cmd = NULL;
+  int retval;
+
+  /* handle incoming data */
+  if (in) {
+    f2b_log_msg(log_debug, "some incoming data on socket %d", conn->sock);
+    char tmp[RBUF_SIZE] = "";
+    char *line = NULL;
+    ssize_t read = 0;
+    read = recv(conn->sock, tmp, RBUF_SIZE, MSG_DONTWAIT);
+    if (read == 0) {
+      f2b_log_msg(log_debug, "received connection close on socket %d", conn->sock);
+      return -1;
+    }
+    if (read < 0) {
+      f2b_log_msg(log_error, "received error on sock %d: %s", conn->sock, strerror(errno));
+      return -1;
+    }
+    if (read > 0) {
+      tmp[read] = '\0';
+      f2b_buf_append(&conn->recv, tmp, read);
+      f2b_log_msg(log_debug, "received %zd bytes from socket %d", read, conn->sock);
+      /* TODO: properly handle empty lines */
+      while (conn->recv.data[0] == '\n') {
+        f2b_buf_splice(&conn->recv, 1);
+        break;
+      }
+      /* extract message(s) */
+      while ((line = f2b_buf_extract(&conn->recv, "\n")) != NULL) {
+        f2b_log_msg(log_debug, "extracted line: %s", line);
+        if ((cmd = f2b_cmd_create(line)) != NULL) {
+          cb(cmd, &conn->send); /* handle command */
+          f2b_cmd_destroy(cmd);
+        } else {
+          f2b_buf_append(&conn->send, "can't parse input\n", 0);
+        }
+        free(line);
+      }
+      if (conn->recv.used >= conn->recv.size) {
+        f2b_log_msg(log_error, "drop connection on socket %d, recv buffer overflow", conn->sock);
+        return -1;
+      }
+    }
+  }
+  /* handle outgoing data */
+  if (conn->send.used > 0) {
+    f2b_log_msg(log_debug, "sending %zu bytes to socket %d", conn->send.used, conn->sock);
+    retval = send(conn->sock, conn->send.data, conn->send.used, MSG_DONTWAIT);
+    if (retval > 0) {
+      f2b_buf_splice(&conn->send, retval);
+      f2b_log_msg(log_debug, "sent %d bytes to socket %d (%zu remains)", retval, conn->sock, conn->send.used);
+    } else if (retval < 0 && errno != EAGAIN) {
+      f2b_log_msg(log_error, "can't send() to socket %d: %s", conn->sock, strerror(errno));
+      return -1; /* remote side closed connection */
+    }
+  }
+  return 0;
+}
+
 /* control socket-related functions */
 
 f2b_csock_t *
@@ -127,7 +186,6 @@ f2b_csocket_poll(f2b_csock_t *csock, void (*cb)(const f2b_cmd_t *cmd, f2b_buf_t
   struct timeval tv = { .tv_sec = 0, .tv_usec = 0 };
   fd_set rfds, wfds;
   f2b_conn_t *conn = NULL;
-  f2b_cmd_t *cmd = NULL;
   int retval, nfds;
 
   assert(csock != NULL);
@@ -140,11 +198,11 @@ f2b_csocket_poll(f2b_csock_t *csock, void (*cb)(const f2b_cmd_t *cmd, f2b_buf_t
   FD_SET(csock->sock, &rfds); /* watch for new connections */
 
   /* watch for new data on established connections */
+  nfds = csock->sock;
   for (int cnum = 0; cnum < MAXCONNS; cnum++) {
     if ((conn = csock->clients[cnum]) == NULL)
       continue;
-    if (!csock->shutdown)
-      FD_SET(conn->sock, &rfds);
+    FD_SET(conn->sock, &rfds);
     if (conn->send.used)
       FD_SET(conn->sock, &wfds);
     nfds = max(csock->sock, conn->sock);
@@ -175,17 +233,17 @@ f2b_csocket_poll(f2b_csock_t *csock, void (*cb)(const f2b_cmd_t *cmd, f2b_buf_t
     int sock = -1;
     /* accept() new connection */
     if ((sock = accept(csock->sock, NULL, NULL)) < 0) {
-      perror("accept()");
+      f2b_log_msg(log_error, "can't accept() new connection: %s", strerror(errno));
     } else if (cnum < MAXCONNS) {
       if ((conn = f2b_conn_create(RBUF_SIZE, WBUF_SIZE)) != NULL) {
-        f2b_log_msg(log_debug, "new connection accept()ed, socket %d, conn %d\n", sock, cnum);
+        f2b_log_msg(log_debug, "new connection accept()ed, socket %d", sock);
         conn->sock = sock;
         csock->clients[cnum] = conn;
       } else {
-        f2b_log_msg(log_error, "can;t create new connection");
+        f2b_log_msg(log_error, "can't create new connection");
       }
     } else {
-      f2b_log_msg(log_error, "max number of clients reached, drop connection on socket %d\n", sock);
+      f2b_log_msg(log_error, "max number of clients reached, drop connection on socket %d", sock);
       shutdown(sock, SHUT_RDWR);
     }
   }
@@ -193,50 +251,11 @@ f2b_csocket_poll(f2b_csock_t *csock, void (*cb)(const f2b_cmd_t *cmd, f2b_buf_t
   for (int cnum = 0; cnum < MAXCONNS; cnum++) {
     if ((conn = csock->clients[cnum]) == NULL)
       continue;
-    /* handle incoming data */
-    if (FD_ISSET(conn->sock, &rfds)) {
-      f2b_log_msg(log_debug, "some incoming data on socket %d", conn->sock);
-      char tmp[RBUF_SIZE] = "";
-      char *line = NULL;
-      ssize_t read = 0;
-      read = recv(conn->sock, tmp, RBUF_SIZE, MSG_DONTWAIT);
-      if (read > 0) {
-        tmp[read] = '\0';
-        f2b_log_msg(log_debug, "conn %d received %zd bytes, and recv buf is now %zd bytes\n", conn->sock, read, conn->recv.used);
-        f2b_buf_append(&conn->recv, tmp, read);
-        /* TODO: properly handle empty lines */
-        while (*conn->recv.data == '\n') {
-          /* TODO f2b_buf_splice(conn->send, retval); */
-          break;
-        }
-        /* extract message(s) */
-        while ((line = f2b_buf_extract(&conn->recv, "\n")) != NULL) {
-          if ((cmd = f2b_cmd_create(line)) != NULL) {
-            cb(cmd, &conn->send); /* handle command */
-            f2b_cmd_destroy(cmd);
-          } else {
-            f2b_buf_append(&conn->send, "can't parse input\n", 0);
-          }
-          free(line);
-        }
-      } else if (read == 0) {
-        f2b_log_msg(log_debug, "received connection close on socket %d", conn->sock);
-        shutdown(conn->sock, SHUT_RDWR);
-        f2b_conn_destroy(conn);
-        csock->clients[cnum] = NULL;
-      } else {
-        perror("recv()");
-      }
-    }
-    /* handle outgoing data */
-    if (conn->send.used > 0) {
-      f2b_log_msg(log_debug, "sending %zu bytes to socket %d\n", conn->send.used, conn->sock);
-      retval = send(conn->sock, conn->send.data, conn->send.used, MSG_DONTWAIT);
-      if (retval > 0) {
-        /* TODO f2b_buf_splice(conn->send, retval); */
-      } else if (retval < 0) {
-        f2b_log_msg(log_error, "can't send %zu bytes to socket %d", conn->send.used, conn->sock);
-      }
+    retval = f2b_conn_process(conn, FD_ISSET(conn->sock, &rfds), cb);
+    if (retval < 0) {
+      shutdown(conn->sock, SHUT_RDWR);
+      f2b_conn_destroy(conn);
+      csock->clients[cnum] = NULL;
     }
   } /* foreach connection(s) */
   return;