1 files changed, 78 insertions, 0 deletions
diff --git a/proto_io.c b/proto_io.c
new file mode 100644
index 0000000..a903546
--- /dev/null
+++ b/proto_io.c
@@ -0,0 +1,78 @@
+/* SPDX-License-Identifier: Unlicense */
+
+#include "proto_io.h"
+
+#include <arpa/inet.h>
+#include <errno.h>
+#include <netinet/in.h>
+#include <sys/socket.h>
+#include <stdio.h>
+
+static unsigned char g_udp_buffer[UINT16_MAX + 1u];
+
+int ReceiveFrame(int fd, struct frame *frame)
+{
+    frame->type = FT_NONE;
+    struct sockaddr_in source_address;
+    socklen_t source_address_len = sizeof(source_address);
+    int const length = recvfrom(
+            fd,
+            g_udp_buffer,
+            sizeof(g_udp_buffer) - 1,
+            0,
+            (struct sockaddr*)&source_address,
+            &source_address_len);
+    if (length == 0) {
+        return -EWOULDBLOCK;
+    }
+    if (length < 0) {
+        int const err = errno;
+        if (err != EWOULDBLOCK) {
+            perror("recvfrom failed");
+        }
+        return -err;
+    }
+    uint32_t const addr = ntohl(source_address.sin_addr.s_addr);
+    uint16_t const port = ntohs(source_address.sin_port);
+    if (length) {
+        *frame = ParseFrame(g_udp_buffer, length);
+        frame->addr = addr;
+        frame->port = port;
+    }
+    if (LOG_TRACE) {
+        uint8_t const a0 = addr >> 24;
+        uint8_t const a1 = addr >> 16;
+        uint8_t const a2 = addr >> 8;
+        uint8_t const a3 = addr;
+        fprintf(stderr, "Received from %u.%u.%u.%u:%u\n", a0, a1, a2, a3, port);
+    }
+    return 0;
+}
+
+int SendFrame(int const fd, struct frame const *const frame)
+{
+    g_udp_buffer[0] = frame->type;
+    struct sockaddr_in const sockaddr = {
+        .sin_family = AF_INET,
+        .sin_port = htons(frame->port),
+        .sin_addr.s_addr = htonl(frame->addr),
+    };
+    if (LOG_TRACE) {
+        uint32_t const addr = frame->addr;
+        uint16_t const port = frame->port;
+        uint8_t const a0 = addr >> 24;
+        uint8_t const a1 = addr >> 16;
+        uint8_t const a2 = addr >> 8;
+        uint8_t const a3 = addr;
+        fprintf(stderr, "Sending to %u.%u.%u.%u:%u\n", a0, a1, a2, a3, port);
+    }
+    size_t const size = SerializeFrame(g_udp_buffer, UINT16_MAX + 1u, frame);
+    ssize_t const ret = sendto(
+            fd, g_udp_buffer, size, 0, (struct sockaddr const *)&sockaddr, sizeof(sockaddr));
+    if (ret < 0) {
+        int const err = errno;
+        perror("sendto failed");
+        return -err;
+    }
+    return 0;
+}