1 files changed, 57 insertions, 0 deletions
diff --git a/prot.h b/prot.h
new file mode 100644
index 0000000..e6eeb05
--- /dev/null
+++ b/prot.h
@@ -0,0 +1,57 @@
+#pragma once
+
+#include <stdint.h>
+
+
+struct prot_msg {
+	uint8_t *data;  // malloc'd buffer, should be free'd by recipient
+	size_t length;  // length of data
+};
+
+
+// The interface exposed here is NOT thread-safe. Having multiple
+// threads in in the same process working with prot is unsafe, since
+// internal communication assumes one calling thread.
+
+
+// This is a channel, a "connection", to another party.
+struct prot;
+
+// Returns a file descriptor that becomes readable in select(2) if
+// there may be a new event on the channel. Do not actually read data
+// from this file descriptor.
+int prot_get_select_fd(struct prot *ch);
+
+// Terminates the connection, blocks until acknowledged. Then channel
+// is closed and freed.
+void prot_terminate(struct prot *ch);
+
+
+// Create channel on which the server can accept new connections using
+// prot_accept(). Only one accept channel can be made in one process.
+struct prot* prot_create_accept_channel();
+
+// Returns a new connection with a client if such an establishment
+// request is ready; an acknowledgement is replied to the request. If
+// no new connection is ready at the moment, the function returns
+// NULL. (This is a non-blocking function.)
+struct prot* prot_accept(struct prot *ach);
+
+
+// Creates a client connection to a server with the specified address.
+// Blocks until the establishment request is acknowledged.
+struct prot* prot_connect(uint32_t server_addr);
+
+
+// Receives a waiting message; returns {.data=NULL} on error, in which
+// case errno is set: EAGAIN = no message ready; ECONNRESET = peer
+// closed connection; other values: internal errors.
+// Channel should not be an accept channel. This is a non-blocking
+// function.
+struct prot_msg prot_recv(struct prot *ch);
+
+// Sends the given data on the given channel. Channel should not be an
+// accept channel. Returns 0 on success and -1 on error, in which case
+// errno is set: ECONNRESET = peer closed connection; other values:
+// internal errors.
+int prot_send(struct prot *ch, const void *data, size_t length);