Using NDK to build ARM aarch64 ELF and running on Android device via adb shell

main.cpp

#include <arpa/inet.h>
#include <netinet/in.h>
#include <sys/socket.h>
#include <unistd.h>
#include <iostream>
#include <cstring>

int main() {

    const char* server_ip = "13.126.18.223"; // server IP
    int port = 11024;

    int sock = socket(AF_INET, SOCK_STREAM, 0);
    if (sock < 0) {
        perror("socket");
        return 1;
    }

    sockaddr_in serv_addr{};
    serv_addr.sin_family = AF_INET;
    serv_addr.sin_port = htons(port);
    inet_pton(AF_INET, server_ip, &serv_addr.sin_addr);

    if (connect(sock, (sockaddr*)&serv_addr, sizeof(serv_addr)) < 0) {
        perror("connect");
        close(sock);
        return 1;
    }

    const char* msg = "Hello from Android NDK TCP client!\n";
    send(sock, msg, strlen(msg), 0);

    char buffer[1024] = {0};
    int n = recv(sock, buffer, sizeof(buffer)-1, 0);
    if (n > 0) {
        buffer[n] = '\0';
        std::cout << "Server replied: " << buffer << std::endl;
    }

    close(sock);
    return 0;
}

Makefile

NDK_PATH      := D:/android_sdk/ndk/25.1.8937393
API_LEVEL     := 21
ABI           := arm64-v8a
BUILD_DIR     := build
SRC_DIR       := .

CXX           := $(NDK_PATH)/toolchains/llvm/prebuilt/windows-x86_64/bin/clang++.exe
CC            := $(NDK_PATH)/toolchains/llvm/prebuilt/windows-x86_64/bin/clang.exe

TARGET_TRIPLE := aarch64-none-linux-android21
SYSROOT       := $(NDK_PATH)/toolchains/llvm/prebuilt/windows-x86_64/sysroot

OPT_LEVEL     := O0
DEBUG_FLAG    := -g

CFLAGS 		  := --target=$(TARGET_TRIPLE) --sysroot=$(SYSROOT) -fPIE -std=gnu99 -$(OPT_LEVEL) $(DEBUG_FLAG)
CXXFLAGS 	  := --target=$(TARGET_TRIPLE) --sysroot=$(SYSROOT) -fPIE -std=c++17 -$(OPT_LEVEL) $(DEBUG_FLAG)
LDFLAGS 	  := --target=$(TARGET_TRIPLE) --sysroot=$(SYSROOT) -fPIE -pie -static-libstdc++


# SRCS_C        := $(SRC_DIR)/api.c
SRCS_CPP      := $(SRC_DIR)/main.cpp
SRCS          := $(SRCS_C) $(SRCS_CPP)

OBJS          := $(patsubst $(SRC_DIR)/%.c,$(BUILD_DIR)/%.o,$(SRCS_C))
OBJS          += $(patsubst $(SRC_DIR)/%.cpp,$(BUILD_DIR)/%.o,$(SRCS_CPP))

TARGET        := $(BUILD_DIR)/main


all: $(TARGET)

$(TARGET): $(OBJS)
	@mkdir -p $(dir $@)
	@echo "Linking: $@"
	$(CXX) $(OBJS) $(LDFLAGS) -o $@

$(BUILD_DIR)/%.o: $(SRC_DIR)/%.c
	@mkdir -p $(dir $@)
	@echo "Compiling C: $< -> $@"
	$(CC) $(CFLAGS) -c $< -o $@

$(BUILD_DIR)/%.o: $(SRC_DIR)/%.cpp
	@mkdir -p $(dir $@)
	@echo "Compiling C++: $< -> $@"
	$(CXX) $(CXXFLAGS) -c $< -o $@

push:
	cmd //C "D:/android_sdk/platform-tools/adb push build/main /data/local/tmp"
	D:/android_sdk/platform-tools/adb shell "chmod +x /data/local/tmp"

adb:
	D:/android_sdk/platform-tools/adb shell

clean:
	@echo "Cleaning up..."
	rm -rf $(BUILD_DIR)

.PHONY: all clean