From 459123928ab5eb8fa3994a7d812ee9ec5838c0f2 Mon Sep 17 00:00:00 2001
From: Niklas Halle <niklas@niklashalle.net>
Date: Thu, 28 May 2020 13:59:46 +0200
Subject: erstes gedöns
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---
 03_exercise/Makefile     |  1 +
 03_exercise/cli/client.c | 67 ++++++++++++++++++++++++++++++++++++++----
 03_exercise/srv/server.c | 75 ++++++++++++++++++++++++++++++++++++++++++------
 3 files changed, 128 insertions(+), 15 deletions(-)

diff --git a/03_exercise/Makefile b/03_exercise/Makefile
index 8c02dc9..dbf4b28 100644
--- a/03_exercise/Makefile
+++ b/03_exercise/Makefile
@@ -18,6 +18,7 @@ all: $(TAR)
 
 run: all
 	srv/server& echo $$! > .srv_pid
+	sleep 1
 	echo "Client Ready:"
 	cli/client
 	kill `cat .srv_pid`
diff --git a/03_exercise/cli/client.c b/03_exercise/cli/client.c
index 48bf724..3cd6f1b 100644
--- a/03_exercise/cli/client.c
+++ b/03_exercise/cli/client.c
@@ -1,13 +1,68 @@
 #include <stdio.h>
+#include <string.h>
 #include <stdlib.h>
 
+#include <unistd.h>
+#include <sys/socket.h>
+#include <netinet/in.h>
+#include <arpa/inet.h>
+
 #define PORT 9000
 #define HOST "127.0.0.1"
 
-int main()
-{
-	getc(stdin);
-	printf("Client Exit\n");
-	
-	return 0;
+static inline void die(const char *msg) {
+    perror(msg);
+    exit(-1);
+}
+
+int main() {
+    struct sockaddr_in addr = {
+            .sin_family = AF_INET,
+            .sin_port = htons(PORT),
+            .sin_addr.s_addr = inet_addr(HOST)
+    };
+    char buf[256];
+    int  cfd;
+
+    if ((cfd = socket(AF_INET, SOCK_STREAM, 0)) < 0)
+        die("Could not open socket");
+
+    if (connect(cfd, (struct sockaddr *) &addr, sizeof(addr)) < 0)
+        die("Could not connect to socket");
+
+    char      *line = NULL;
+    size_t    cap   = 0;
+    __ssize_t length;
+
+    while (1) {
+        if ((length = getline(&line, &cap, stdin)) < 0) {
+            fprintf(stderr, "Failed to read from STDIN");
+            fflush(stderr);
+            exit(-1);
+        }
+
+        if (strspn(line, " \n\t") == strlen(line)) {
+            // skip empty lines - empty being just spaces or tabs
+            continue;
+        }
+
+        line[length - 1] = '\0'; // cut the line feed
+
+        if (strcmp(line, "exit") == 0) {
+            break;
+        }
+
+        strncpy(buf, line, strlen(line));
+
+        if (write(cfd, buf, sizeof(buf)) < 0)
+            die("Could not send message");
+
+        if (read(cfd, buf, sizeof(buf)) < 0)
+            die("Could not receive message");
+
+        printf("$> %s\n", buf);
+    }
+
+    close(cfd);
+    return 0;
 }
diff --git a/03_exercise/srv/server.c b/03_exercise/srv/server.c
index 972b11f..bb2b3ab 100644
--- a/03_exercise/srv/server.c
+++ b/03_exercise/srv/server.c
@@ -1,16 +1,73 @@
 #include <stdio.h>
+#include <string.h>
 #include <stdlib.h>
+
 #include <unistd.h>
+#include <sys/socket.h>
+#include <netinet/in.h>
+#include <arpa/inet.h>
 
 #define PORT 9000
 
-int main()
-{
-	while (1)
-	{
-		printf("[srv]: idle\n");
-		sleep(2);
-	}
-	
-	return 0;
+static inline void die(const char *msg) {
+    perror(msg);
+    exit(-1);
+}
+
+int main() {
+    struct sockaddr_in srv_addr, cli_addr;
+    int       sockopt = 1;
+    socklen_t sad_sz  = sizeof(struct sockaddr_in);
+    int       sfd, cfd;
+    ssize_t   bytes;
+    char      in_buf[256];
+    char      out_buf[256];
+
+    srv_addr.sin_family      = AF_INET;
+    srv_addr.sin_port        = htons(PORT);
+    srv_addr.sin_addr.s_addr = INADDR_ANY;
+
+    if ((sfd = socket(AF_INET, SOCK_STREAM, 0)) < 0)
+        die("Could not open socket");
+
+    setsockopt(sfd, SOL_SOCKET, SO_REUSEADDR, (char *) &sockopt, sizeof(sockopt));
+
+    if (bind(sfd, (struct sockaddr *) &srv_addr, sad_sz) < 0)
+        die("Could not bind socket");
+
+    if (listen(sfd, 1) < 0)
+        die("Could not listen on socket");
+
+    cfd = accept(sfd, (struct sockaddr *) &cli_addr, &sad_sz);
+    if (cfd < 0)
+        die("Could not accept incoming connection");
+
+    printf("srv: connected: %s\n", inet_ntoa(cli_addr.sin_addr));
+
+    while ((bytes = read(cfd, in_buf, sizeof(in_buf))) != 0) {
+        if (bytes < 0)
+            die("Couldn't receive message");
+
+        printf("srv: %s\n", in_buf);
+
+        if (strcmp(in_buf, "get") == 0) {
+            // TODO: implement get
+        } else if (strcmp(in_buf, "put") == 0) {
+            // TODO: implement put
+        } else if (strcmp(in_buf, "ping") == 0) {
+            strncpy(out_buf, "pong!", sizeof(out_buf));
+        } else {
+            // TODO: connect our shell implementation
+            strncpy(out_buf, "got: ", sizeof(out_buf));
+            strncpy(out_buf + sizeof("got: "), in_buf, sizeof(out_buf) - sizeof("got: "));
+        }
+
+        if (write(cfd, out_buf, sizeof(out_buf)) < 0)
+            die("Couldn't send message");
+    }
+
+    printf("srv: closing down\n");
+
+    close(cfd);
+    close(sfd);
 }
-- 
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