gistfile1.txt

#include <sys/types.h>
#include <time.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <stdbool.h>
#include <ifaddrs.h>

#define PORT (23875)
#define MAGIC (0x13AE83BD)

int Server(FILE *file) {
	{
		struct ifaddrs *addrs, *tmp;
		getifaddrs(&addrs);
		tmp = addrs;

		while (tmp) {
			if (tmp->ifa_addr && tmp->ifa_addr->sa_family == AF_INET) {
				struct sockaddr_in *pAddr = (struct sockaddr_in *)tmp->ifa_addr;

				if (tmp->ifa_name[0] == 'w') {
					printf("%s: %s\n", tmp->ifa_name, inet_ntoa(pAddr->sin_addr));
				}
			}

			tmp = tmp->ifa_next;
		}

		freeifaddrs(addrs);
	}

	int socketHandle = socket(PF_INET, SOCK_STREAM, IPPROTO_TCP);

	if (socketHandle == -1) {
		perror("Socket failed");
		return 1;
	}

	int enable = 1;
	setsockopt(socketHandle, SOL_SOCKET, SO_REUSEADDR, &enable, sizeof(enable));

	struct sockaddr_in address = { 0 };
	address.sin_family = AF_INET;
	address.sin_port = htons(PORT);
	address.sin_addr.s_addr = htonl(INADDR_ANY);

	if (bind(socketHandle, (struct sockaddr *) &address, sizeof(address)) == -1) {
		perror("Bind failed");
		close(socketHandle);
		return 1;
	}

	if (listen(socketHandle, 1) == -1) {
		perror("Listen failed");
		close(socketHandle);
		return 1;
	}

	int connectionHandle = accept(socketHandle, NULL, NULL);

	if (connectionHandle == -1) {
		perror("Accept failed");
		close(socketHandle);
		return 1;
	}

	uint32_t magic = MAGIC;
	write(connectionHandle, &magic, sizeof(magic));

	while (true) {
		char buffer[4096];
		uint32_t bytesRead = fread(buffer, 1, sizeof(buffer), file);
		write(connectionHandle, &bytesRead, sizeof(bytesRead));
		if (!bytesRead) break;

		if (bytesRead != write(connectionHandle, buffer, bytesRead)) {
			printf("Transfer failed (short write).\n");
			break;
		}
	}

	shutdown(connectionHandle, SHUT_RDWR);
	close(connectionHandle);
	close(socketHandle);
	return 0;
}

int Client(FILE *file, int ipLastBit) {
	int socketHandle = socket(PF_INET, SOCK_STREAM, IPPROTO_TCP);

	if (socketHandle == -1) {
		perror("Socket failed");
		return 1;
	}

	char ipAddress[32] = "192.168.1.";
	sprintf(ipAddress + strlen(ipAddress), "%d", ipLastBit);
	struct sockaddr_in address = { 0 };
	address.sin_family = AF_INET;
	address.sin_port = htons(PORT);
	inet_pton(AF_INET, ipAddress, &address.sin_addr);

	if (connect(socketHandle, (struct sockaddr *) &address, sizeof(address)) == -1) {
		perror("Connect failed");
		close(socketHandle);
		return 1;
	}
	
	bool success = false;

	uint32_t magic = 0;
	read(socketHandle, &magic, sizeof(magic));

	if (magic != MAGIC) {
		printf("Error: Magic number mismatch.\n");
		close(socketHandle);
		return 1;
	}

	size_t totalWritten = 0;
	size_t lastReported = 0;
	uint64_t startTime = time(NULL);

	while (true) {
		char buffer[4096];
		uint32_t byteCount;
		size_t bytesRead = read(socketHandle, &byteCount, sizeof(byteCount));
		if (bytesRead != sizeof(byteCount) || byteCount > sizeof(buffer)) break;
		if (byteCount == 0) { success = true; break; }

		while (byteCount) {
			bytesRead = read(socketHandle, buffer, byteCount);
			if (!bytesRead) break;
			fwrite(buffer, 1, bytesRead, file);
			totalWritten += bytesRead;
			byteCount -= bytesRead;

			if (totalWritten - lastReported > 10000000) {
				printf("%d MB received...\n", totalWritten / 1000000);
				lastReported = totalWritten;
			}
		}
	}

	uint64_t endTime = time(NULL);
	if (!success) printf("Error: The transfer didn't complete.\n");
	else printf("Transfer complete in %d seconds (average speed: %.1f MB/s).\n", (int) (endTime - startTime), 
			(double) totalWritten / (endTime - startTime) / 1000000.0);
	close(socketHandle);
	return 0;
}

int main(int argc, char **argv) {
	if (argc < 2) {
		fprintf(stderr, "Usage: %s <send/receive> <options>\n", argv[0]);
		exit(1);
	}

	bool server = 0 == strcmp(argv[1], "send");

	if (!server && strcmp(argv[1], "receive")) {
		fprintf(stderr, "Usage: %s <send/receive> <options>\n", argv[0]);
		exit(1);
	}

	if (server && argc != 3) {
		fprintf(stderr, "Usage: %s send <file>\n", argv[0]);
		exit(1);
	}

	if (!server && argc != 4) {
		fprintf(stderr, "Usage: %s receive <file> <ip-last-bit>\n", argv[0]);
		exit(1);
	}

	FILE *f = fopen(argv[2], server ? "rb" : "wb");

	if (!f) {
		fprintf(stderr, "Error: Could not open file '%s'.\n", argv[2]);
		exit(1);
	}

	return server ? Server(f) : Client(f, atoi(argv[3]));
}