From e272d5f279a1e2e6543123f684d964f82475db48 Mon Sep 17 00:00:00 2001
From: Steffen Vogel <post@steffenvogel.de>
Date: Sat, 11 Apr 2015 18:05:01 +0200
Subject: [PATCH] added first session UDP echo server and client

---
 .gitignore                      |  1 +
 session1/udp_echo/Makefile      | 14 +++++++
 session1/udp_echo/echo_client.c | 67 +++++++++++++++++++++++++++++++++
 session1/udp_echo/echo_server.c | 65 ++++++++++++++++++++++++++++++++
 4 files changed, 147 insertions(+)
 create mode 100644 .gitignore
 create mode 100644 session1/udp_echo/Makefile
 create mode 100644 session1/udp_echo/echo_client.c
 create mode 100644 session1/udp_echo/echo_server.c

diff --git a/.gitignore b/.gitignore
new file mode 100644
index 0000000..5761abc
--- /dev/null
+++ b/.gitignore
@@ -0,0 +1 @@
+*.o
diff --git a/session1/udp_echo/Makefile b/session1/udp_echo/Makefile
new file mode 100644
index 0000000..e506f94
--- /dev/null
+++ b/session1/udp_echo/Makefile
@@ -0,0 +1,14 @@
+TARGETS = echo_server echo_client
+
+CC = gcc
+CFLAGS = -g -D$(DEFINES)
+
+all: $(TARGETS) Makefile
+clean:
+	rm -f $(TARGETS)
+	rm -f *.o *.~
+
+echo_server: echo_server.o
+echo_client: echo_client.o	
+
+.PHONY: all clean
diff --git a/session1/udp_echo/echo_client.c b/session1/udp_echo/echo_client.c
new file mode 100644
index 0000000..5edd6e8
--- /dev/null
+++ b/session1/udp_echo/echo_client.c
@@ -0,0 +1,67 @@
+#include <stdlib.h>
+#include <stdio.h>
+#include <errno.h>
+#include <string.h>
+
+#include <sys/socket.h>
+#include <netinet/in.h>
+#include <arpa/inet.h>
+
+
+void handle_error(char *msg)
+{
+	fprintf(stderr, "%s: %s\n", msg, strerror(errno));
+
+	exit(EXIT_FAILURE);
+}
+
+
+int main(int argc, char *argv[])
+{
+	int fd;
+	char *lineptr = NULL;
+	ssize_t linelen = 0;
+
+	struct sockaddr_in sa = { .sin_family = AF_INET };
+
+	if (argc != 3) {
+		printf("usage: %s DEST-IP PORT\n", argv[0]);
+		exit(-1);
+	}
+
+	if (!inet_aton(argv[1], &sa.sin_addr))
+		fprintf(stderr, "Failed to parse destination IP address\n");
+
+	sa.sin_port = atoi(argv[2]);
+	if (!sa.sin_port)
+		fprintf(stderr, "Failed to parse port number");
+
+	fd = socket(AF_INET, SOCK_DGRAM, 0);
+	if (fd < 0)
+		handle_error("Failed to create socket");
+
+	if (connect(fd, (struct sockaddr *) &sa, sizeof(sa)))
+		handle_error("Failed to connect socket");
+
+	while (!feof(stdin)) {
+		size_t len = getline(&lineptr, &linelen, stdin);
+		if (len > 0) {
+			if (send(fd, lineptr, len+1, 0) == -1)
+				handle_error("Failed to send");
+
+#ifdef ECHO
+			if (recv(fd, lineptr, linelen, 0) == -1)
+				handle_error("Failed to recv");
+
+			fprintf(stdout, "%s", lineptr);
+#endif
+		}
+	}
+
+	if (close(fd))
+		handle_error("Failed to close socket");
+
+	free(lineptr);
+
+	return 0;
+}
diff --git a/session1/udp_echo/echo_server.c b/session1/udp_echo/echo_server.c
new file mode 100644
index 0000000..b1fd40d
--- /dev/null
+++ b/session1/udp_echo/echo_server.c
@@ -0,0 +1,65 @@
+#include <stdlib.h>
+#include <stdio.h>
+#include <errno.h>
+#include <string.h>
+
+#include <sys/socket.h>
+#include <netinet/in.h>
+#include <arpa/inet.h>
+
+
+void handle_error(char *msg)
+{
+	fprintf(stderr, "%s: %s\n", msg, strerror(errno));
+
+	exit(EXIT_FAILURE);
+}
+
+
+int main(int argc, char *argv[])
+{
+	int fd;
+	char line[1024];
+	ssize_t msglen;
+	socklen_t salen;
+
+	struct sockaddr_in sa = { .sin_family = AF_INET };
+
+	if (argc != 2) {
+		printf("usage: %s PORT\n", argv[0]);
+		exit(-1);
+	}
+
+	sa.sin_port = atoi(argv[1]);
+	if (!sa.sin_port)
+		fprintf(stderr, "Failed to parse port number");
+
+
+	fd = socket(AF_INET, SOCK_DGRAM, 0);
+	if (fd < 0)
+		handle_error("Failed to create socket");
+
+	if (bind(fd, (struct sockaddr *) &sa, sizeof(sa)))
+		handle_error("Failed to bind socket");
+
+	while (1) {
+		salen = sizeof(sa);
+
+		msglen = recvfrom(fd, &line, sizeof(line), 0, (struct sockaddr *) &sa, &salen)
+		if (msglen == -1)
+			handle_error("Failed to recv");
+
+#ifdef ECHO
+		if (sendto(fd, &line, msglen, 0,
+			(struct sockaddr *) &sa, salen) == -1)
+			handle_error("Failed to send");
+#else
+		fprintf(stdout, "%s", line);
+#endif
+	}
+
+	if (close(fd))
+		handle_error("Failed to close socket");
+
+	return 0;
+}