From a903588ed52a877db413f72a018570fb6810ad2c Mon Sep 17 00:00:00 2001
From: Akshay <nerdy@peppe.rs>
Date: Wed, 4 Nov 2020 19:21:35 +0530
Subject: add concurrent, iterative and UDP servers

---
 q6/a/client.c | 47 +++++++++++++++++++++++++++++++++++++++++++++++
 q6/a/server.c | 49 +++++++++++++++++++++++++++++++++++++++++++++++++
 q6/b/client.c | 47 +++++++++++++++++++++++++++++++++++++++++++++++
 q6/b/server.c | 44 ++++++++++++++++++++++++++++++++++++++++++++
 q6/c/client.c | 41 +++++++++++++++++++++++++++++++++++++++++
 q6/c/server.c | 38 ++++++++++++++++++++++++++++++++++++++
 6 files changed, 266 insertions(+)
 create mode 100644 q6/a/client.c
 create mode 100644 q6/a/server.c
 create mode 100644 q6/b/client.c
 create mode 100644 q6/b/server.c
 create mode 100644 q6/c/client.c
 create mode 100644 q6/c/server.c

diff --git a/q6/a/client.c b/q6/a/client.c
new file mode 100644
index 0000000..7219476
--- /dev/null
+++ b/q6/a/client.c
@@ -0,0 +1,47 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <sys/types.h>
+#include <sys/socket.h>
+#include <netinet/in.h>
+#include <unistd.h>
+#include <string.h>
+#include <arpa/inet.h>
+#include <string.h>
+
+int main(int argc, char* argv[]) { 
+    const char *server_name = "127.0.0.1";
+    int sockfd, connfd; 
+    struct sockaddr_in servaddr, cli; 
+
+    sockfd = socket(AF_INET, SOCK_STREAM, 0); 
+    servaddr.sin_family = AF_INET; 
+    inet_pton(AF_INET, server_name, &servaddr.sin_addr);
+
+    int port = atoi(argv[1]);
+    servaddr.sin_port = htons(port);
+
+    if((connect(sockfd, (struct sockaddr*)&servaddr, sizeof(servaddr))) == 0) {
+        printf("Connected to server!\n");
+        fflush(stdout);
+    } else {
+        printf("Invalid or busy server address\n");
+        fflush(stdout);
+        exit(0);
+    };
+
+    int cont = 0;
+    char *buf = malloc(1024);
+    printf("Client input: ");
+    fgets(buf, 100, stdin);
+    while(strcmp(buf, "quit\n") != 0) {
+        send(sockfd, buf, 100, 0);
+        if ((cont = recv(sockfd, buf, 100, 0)) > 0) {
+            printf("Server response: %s\n", buf);;
+            fflush(stdout);
+        }
+        printf("Client input: ");
+        fgets(buf, 100, stdin);
+    };
+
+    close(sockfd); 
+}
diff --git a/q6/a/server.c b/q6/a/server.c
new file mode 100644
index 0000000..ac258c0
--- /dev/null
+++ b/q6/a/server.c
@@ -0,0 +1,49 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <sys/types.h>
+#include <sys/socket.h>
+#include <netinet/in.h>
+#include <unistd.h>
+#include <string.h>
+#include <arpa/inet.h>
+
+int main(int argc, char *argv[]) {
+    int sockfd, connfd; 
+    struct sockaddr_in servaddr, cli; 
+  
+    sockfd = socket(AF_INET, SOCK_STREAM, 0); 
+    servaddr.sin_family = AF_INET; 
+    servaddr.sin_addr.s_addr = htonl(INADDR_ANY); 
+
+    int port = atoi(argv[1]);
+    servaddr.sin_port = htons(port);
+  
+    bind(sockfd, (struct sockaddr *)&servaddr, sizeof(servaddr));
+  
+    listen(sockfd, 128);
+    printf("Server started at %s...\n", inet_ntoa(servaddr.sin_addr));
+    fflush(stdout);
+
+    while(1) {
+        socklen_t len = sizeof(cli);
+        connfd = accept(sockfd, (struct sockaddr *)&cli, &len);
+        int i = getpeername(connfd, (struct sockaddr*)&cli, &len);
+
+        printf("Client connected at port %d\n", htons(cli.sin_port));
+        int n;
+        char buf[100];
+
+        int pid;
+        if((pid=fork())==0){
+            close(sockfd);
+            while((n = recv(connfd, buf, 100, 0)) > 0) {
+                printf("Client message: %s\n", buf);
+                fflush(stdout);
+                send(connfd, buf, n, 0);
+            };
+            exit(0);
+        }
+        close(connfd);
+    }
+    return 0;
+}
diff --git a/q6/b/client.c b/q6/b/client.c
new file mode 100644
index 0000000..7219476
--- /dev/null
+++ b/q6/b/client.c
@@ -0,0 +1,47 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <sys/types.h>
+#include <sys/socket.h>
+#include <netinet/in.h>
+#include <unistd.h>
+#include <string.h>
+#include <arpa/inet.h>
+#include <string.h>
+
+int main(int argc, char* argv[]) { 
+    const char *server_name = "127.0.0.1";
+    int sockfd, connfd; 
+    struct sockaddr_in servaddr, cli; 
+
+    sockfd = socket(AF_INET, SOCK_STREAM, 0); 
+    servaddr.sin_family = AF_INET; 
+    inet_pton(AF_INET, server_name, &servaddr.sin_addr);
+
+    int port = atoi(argv[1]);
+    servaddr.sin_port = htons(port);
+
+    if((connect(sockfd, (struct sockaddr*)&servaddr, sizeof(servaddr))) == 0) {
+        printf("Connected to server!\n");
+        fflush(stdout);
+    } else {
+        printf("Invalid or busy server address\n");
+        fflush(stdout);
+        exit(0);
+    };
+
+    int cont = 0;
+    char *buf = malloc(1024);
+    printf("Client input: ");
+    fgets(buf, 100, stdin);
+    while(strcmp(buf, "quit\n") != 0) {
+        send(sockfd, buf, 100, 0);
+        if ((cont = recv(sockfd, buf, 100, 0)) > 0) {
+            printf("Server response: %s\n", buf);;
+            fflush(stdout);
+        }
+        printf("Client input: ");
+        fgets(buf, 100, stdin);
+    };
+
+    close(sockfd); 
+}
diff --git a/q6/b/server.c b/q6/b/server.c
new file mode 100644
index 0000000..e217c2b
--- /dev/null
+++ b/q6/b/server.c
@@ -0,0 +1,44 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <sys/types.h>
+#include <sys/socket.h>
+#include <netinet/in.h>
+#include <unistd.h>
+#include <string.h>
+#include <arpa/inet.h>
+
+int main(int argc, char *argv[]) {
+    int sockfd, connfd; 
+    struct sockaddr_in servaddr, cli; 
+  
+    sockfd = socket(AF_INET, SOCK_STREAM, 0); 
+    servaddr.sin_family = AF_INET; 
+    servaddr.sin_addr.s_addr = htonl(INADDR_ANY); 
+
+    int port = atoi(argv[1]);
+    servaddr.sin_port = htons(port);
+  
+    bind(sockfd, (struct sockaddr *)&servaddr, sizeof(servaddr));
+  
+    listen(sockfd, 128);
+    printf("Server started at %s...\n", inet_ntoa(servaddr.sin_addr));
+    fflush(stdout);
+
+    while(1) {
+        socklen_t len = sizeof(cli);
+        connfd = accept(sockfd, (struct sockaddr *)&cli, &len);
+        int i = getpeername(connfd, (struct sockaddr*)&cli, &len);
+
+        printf("Client connected at port %d\n", htons(cli.sin_port));
+        int n;
+        char buf[100];
+
+        while((n = recv(connfd, buf, 100, 0)) > 0) {
+            printf("Client message: %s\n", buf);
+            fflush(stdout);
+            send(connfd, buf, n, 0);
+        };
+        close(connfd);
+    }
+    return 0;
+}
diff --git a/q6/c/client.c b/q6/c/client.c
new file mode 100644
index 0000000..12e00fa
--- /dev/null
+++ b/q6/c/client.c
@@ -0,0 +1,41 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+#include <sys/types.h>
+#include <sys/socket.h>
+#include <arpa/inet.h>
+#include <netinet/in.h>
+#include <string.h>
+
+int main(int argc, char *argv[]) {
+    int sockfd;
+    struct sockaddr_in servaddr;
+    sockfd = socket(AF_INET, SOCK_DGRAM, 0);
+
+    servaddr.sin_family = AF_INET; 
+    servaddr.sin_addr.s_addr = htonl(INADDR_ANY); 
+
+    int port = atoi(argv[1]);
+    servaddr.sin_port = htons(port);
+
+    int n; 
+
+    socklen_t len = sizeof(servaddr);
+    char *buf = malloc(100);
+    fgets(buf, 100, stdin);
+    while(strcmp(buf, "quit\n") != 0) {
+        sendto(sockfd, buf, strlen(buf), 
+                MSG_CONFIRM, (const struct sockaddr *) &servaddr,  
+                sizeof(servaddr)); 
+
+        n = recvfrom(sockfd, buf, 100,  
+                MSG_WAITALL, (struct sockaddr *) &servaddr, 
+                &len); 
+        printf("Recieved: %s", buf);
+        fgets(buf, 100, stdin);
+    }
+
+    close(sockfd); 
+    return 0;
+}
diff --git a/q6/c/server.c b/q6/c/server.c
new file mode 100644
index 0000000..4b25070
--- /dev/null
+++ b/q6/c/server.c
@@ -0,0 +1,38 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+#include <sys/types.h>
+#include <sys/socket.h>
+#include <arpa/inet.h>
+#include <netinet/in.h>
+
+int main(int argc, char *argv[]) {
+    int sockfd;
+    struct sockaddr_in servaddr, cli; 
+    sockfd = socket(AF_INET, SOCK_DGRAM, 0);
+
+    servaddr.sin_family = AF_INET; 
+    servaddr.sin_addr.s_addr = htonl(INADDR_ANY); 
+
+    int port = atoi(argv[1]);
+    servaddr.sin_port = htons(port);
+
+    bind(sockfd, (struct sockaddr *)&servaddr, sizeof(servaddr));
+
+    socklen_t len = sizeof(cli);
+    while(1) {
+        int n;
+        char *buf = malloc(100);
+        while(
+                (n = recvfrom(sockfd, (char *)buf, 100, MSG_WAITALL, (struct sockaddr*) &cli, &len))
+                > 0
+             ) {
+            printf("Client message: %s\n", buf);
+            fflush(stdout);
+            sendto(sockfd, buf, n, MSG_CONFIRM, (const struct sockaddr *) &cli, len);
+        }
+    }
+    close(sockfd);
+    return 0;
+}
-- 
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