Initial commit

5 files changed, 140 insertions, 0 deletions

diff --git a/.gitignore b/.gitignore
new file mode 100644
index 0000000..3a1c77f
--- /dev/null
+++ b/.gitignore
@@ -0,0 +1,7 @@
+compile_commands.json
+*.o
+*.d
+cmake[-_]build*/
+build/
+client
+server
diff --git a/CMakeLists.txt b/CMakeLists.txt
new file mode 100644
index 0000000..ec05a85
--- /dev/null
+++ b/CMakeLists.txt
@@ -0,0 +1,47 @@
+# SPDX-License-Identifier: Unlicense
+
+cmake_minimum_required(VERSION 3.16)
+
+set(CMAKE_EXPORT_COMPILE_COMMANDS True)
+
+project(udp-tinkering)
+
+set(common_debug_flags
+    -g3
+    -fsanitize=address,undefined
+    -fno-omit-frame-pointer
+    -O1
+    )
+set(compile_flags
+    $<$<CONFIG:Debug>:${common_debug_flags}>
+    $<$<COMPILE_LANGUAGE:C>:-Wno-nested-anon-types>
+    $<$<COMPILE_LANGUAGE:CXX>:-fno-exceptions>
+    $<$<COMPILE_LANGUAGE:CXX>:-fno-rtti>
+    $<$<COMPILE_LANGUAGE:CXX>:-Wold-style-cast>
+    $<$<COMPILE_LANGUAGE:CXX>:-Wsuggest-override>
+    $<$<COMPILE_LANG_AND_ID:CXX,GNU>:-Wsuggest-final-types>
+    $<$<COMPILE_LANG_AND_ID:CXX,GNU>:-Wsuggest-final-methods>
+    $<$<COMPILE_LANG_AND_ID:CXX,GNU>:-fstrict-volatile-bitfields>
+    $<$<COMPILE_LANG_AND_ID:C,GNU>:-fstrict-volatile-bitfields>
+    $<$<COMPILE_LANG_AND_ID:CXX,GNU>:-Wlogical-op>
+    $<$<COMPILE_LANG_AND_ID:C,GNU>:-Wlogical-op>
+    $<$<COMPILE_LANG_AND_ID:CXX,GNU>:-ffile-prefix-map=${CMAKE_SOURCE_DIR}/=>
+    $<$<COMPILE_LANG_AND_ID:C,GNU>:-ffile-prefix-map=${CMAKE_SOURCE_DIR}/=>
+    -Wall
+    -Wextra
+    -pedantic
+    -Wcast-align
+    -Wshadow
+    )
+
+add_executable(server server.c)
+target_compile_options(server PRIVATE ${compile_flags})
+target_compile_definitions(server PRIVATE _FORTIFY_SOURCE=2)
+target_link_options(server PRIVATE $<$<CONFIG:Debug>:${common_debug_flags}>)
+target_include_directories(server PRIVATE .)
+
+add_executable(client client.c)
+target_compile_options(client PRIVATE ${compile_flags})
+target_compile_definitions(client PRIVATE _FORTIFY_SOURCE=2)
+target_link_options(client PRIVATE $<$<CONFIG:Debug>:${common_debug_flags}>)
+target_include_directories(client PRIVATE .)
diff --git a/Readme.md b/Readme.md
new file mode 100644
index 0000000..5f8e8b4
--- /dev/null
+++ b/Readme.md
@@ -0,0 +1,19 @@
+# UDP tinkering
+
+I want to build server and client for researching how I can do certain things
+with UDP and what limits are.
+
+UDP related thoughts:
+
+- What packet loss looks like?
+- What packet reordering looks like? Is it even a thing?
+- Is packet loss really lower when traffic is paced uniformly instead of
+  sporadic bursts of messages?
+- Does message length impact packet loss or packet reordering?
+- Can UDP packet be corrupted?
+- Can I make UDP hole punching work just off of a custom UDP server?
+
+And not UDP related, but rather related to my intended usage of UDP things:
+- Implement some simulation synchronization by time based on ping roundtrip time
+  or something (how does NTP even work?).
+- Implement file transferring.
diff --git a/client.c b/client.c
new file mode 100644
index 0000000..524a0a8
--- /dev/null
+++ b/client.c
@@ -0,0 +1,31 @@
+// Initially based on https://stackoverflow.com/a/35570418
+
+#include <netinet/in.h>
+#include <stdio.h>
+#include <string.h>
+#include <sys/socket.h>
+#include <unistd.h>
+
+int main(void)
+{
+    int const fd = socket(AF_INET, SOCK_DGRAM, 0);
+    if (fd < 0) {
+        perror("socket failed");
+        return 1;
+    }
+    struct sockaddr_in const serveraddr = {
+        .sin_family = AF_INET,
+        .sin_port = htons(50037),
+        .sin_addr.s_addr = htonl(0x7f000001),
+    };
+    for (int i = 0; i < 4; i++) {
+        ssize_t const ret = sendto(
+                fd, "hello", 5, 0, (struct sockaddr const *)&serveraddr, sizeof(serveraddr));
+        if (ret < 0) {
+            perror("sendto failed");
+            break;
+        }
+        printf("message sent\n");
+    }
+    close(fd);
+}
diff --git a/server.c b/server.c
new file mode 100644
index 0000000..e35a9b5
--- /dev/null
+++ b/server.c
@@ -0,0 +1,36 @@
+// Initially based on https://stackoverflow.com/a/35570418
+
+#include <netinet/in.h>
+#include <stdio.h>
+#include <string.h>
+#include <sys/socket.h>
+#include <unistd.h>
+
+int main(void)
+{
+    int const fd = socket(AF_INET, SOCK_DGRAM, 0);
+    if (fd < 0) {
+        perror("socket failed");
+        return 1;
+    }
+    struct sockaddr_in const serveraddr = {
+        .sin_family = AF_INET,
+        .sin_port = htons(50037),
+        .sin_addr.s_addr = htonl(INADDR_ANY),
+    };
+    if (bind(fd, (struct sockaddr *)&serveraddr, sizeof(serveraddr)) < 0) {
+        perror("bind failed");
+        return 1;
+    }
+    for (;;) {
+        char buffer[200];
+        int const length = recvfrom(fd, buffer, sizeof(buffer) - 1, 0, NULL, 0);
+        if (length < 0) {
+            perror("recvfrom failed");
+            break;
+        }
+        buffer[length] = '\0';
+        printf("%d bytes: '%s'\n", length, buffer);
+    }
+    close(fd);
+}