From 5ad3b0ef0412c45af7752d5011976242bf3fc710 Mon Sep 17 00:00:00 2001
From: "Glenn Y. Rolland" <glenux@glenux.net>
Date: Mon, 5 Sep 2016 15:06:26 +0200
Subject: [PATCH] Added udp/tcp client from Beejs network tutorial

---
 Makefile         |  2 +-
 src/udp-client.c | 68 ++++++++++++++++++++++++++++++++++
 src/udp-server.c | 95 ++++++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 164 insertions(+), 1 deletion(-)
 create mode 100644 src/udp-client.c
 create mode 100644 src/udp-server.c

diff --git a/Makefile b/Makefile
index c504181..56ef00b 100644
--- a/Makefile
+++ b/Makefile
@@ -9,7 +9,7 @@ TEST_SRC  = $(wildcard test/*.c)
 TEST_BINS = $(patsubst test/%,bin/%,$(patsubst %.c,%.test,$(TEST_SRC)))
 
 # CFLAGS  = -std=c99 -Ideps -Wall -Wno-unused-function -U__STRICT_ANSI__
-CFLAGS  = -ggdb -std=c99 -Ideps -Ilib -Wall -Wno-unused-function -pedantic 
+CFLAGS  = -ggdb -std=c99 -Ideps -Ilib -Wall -Wno-unused-function -pedantic -D_POSIX_C_SOURCE=200112L
 
 
 all: $(BINS) $(TEST_BINS)
diff --git a/src/udp-client.c b/src/udp-client.c
new file mode 100644
index 0000000..6149a6d
--- /dev/null
+++ b/src/udp-client.c
@@ -0,0 +1,68 @@
+/*
+** talker.c -- a datagram "client" demo
+*/
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include <errno.h>
+#include <string.h>
+#include <sys/types.h>
+#include <sys/socket.h>
+#include <netinet/in.h>
+#include <arpa/inet.h>
+#include <netdb.h>
+
+#define SERVERPORT "4950"    // the port users will be connecting to
+
+int main(int argc, char *argv[])
+{
+    int sockfd;
+    struct addrinfo *servinfo, *p;
+    struct addrinfo hints;
+    int rv;
+    int numbytes;
+
+    if (argc != 3) {
+        fprintf(stderr,"usage: talker hostname message\n");
+        exit(1);
+    }
+
+    memset(&hints, 0, sizeof hints);
+    hints.ai_family = AF_UNSPEC;
+    hints.ai_socktype = SOCK_DGRAM;
+
+    if ((rv = getaddrinfo(argv[1], SERVERPORT, &hints, &servinfo)) != 0) {
+        fprintf(stderr, "getaddrinfo: %s\n", gai_strerror(rv));
+        return 1;
+    }
+
+    // loop through all the results and make a socket
+    for(p = servinfo; p != NULL; p = p->ai_next) {
+        if ((sockfd = socket(p->ai_family, p->ai_socktype,
+                p->ai_protocol)) == -1) {
+            perror("talker: socket");
+            continue;
+        }
+
+        break;
+    }
+
+    if (p == NULL) {
+        fprintf(stderr, "talker: failed to create socket\n");
+        return 2;
+    }
+
+    if ((numbytes = sendto(sockfd, argv[2], strlen(argv[2]), 0,
+             p->ai_addr, p->ai_addrlen)) == -1) {
+        perror("talker: sendto");
+        exit(1);
+    }
+
+    freeaddrinfo(servinfo);
+
+    printf("talker: sent %d bytes to %s\n", numbytes, argv[1]);
+    close(sockfd);
+
+    return 0;
+}
diff --git a/src/udp-server.c b/src/udp-server.c
new file mode 100644
index 0000000..c2f5374
--- /dev/null
+++ b/src/udp-server.c
@@ -0,0 +1,95 @@
+/*
+** listener.c -- a datagram sockets "server" demo
+*/
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include <errno.h>
+#include <string.h>
+#include <sys/types.h>
+#include <sys/socket.h>
+#include <netinet/in.h>
+#include <arpa/inet.h>
+#include <netdb.h>
+
+#define MYPORT "4950"    // the port users will be connecting to
+
+#define MAXBUFLEN 100
+
+// get sockaddr, IPv4 or IPv6:
+void *get_in_addr(struct sockaddr *sa)
+{
+    if (sa->sa_family == AF_INET) {
+        return &(((struct sockaddr_in*)sa)->sin_addr);
+    }
+
+    return &(((struct sockaddr_in6*)sa)->sin6_addr);
+}
+
+int main(void)
+{
+    int sockfd;
+    struct addrinfo hints, *servinfo, *p;
+    int rv;
+    int numbytes;
+    struct sockaddr_storage their_addr;
+    char buf[MAXBUFLEN];
+    socklen_t addr_len;
+    char s[INET6_ADDRSTRLEN];
+
+    memset(&hints, 0, sizeof hints);
+    hints.ai_family = AF_UNSPEC; // set to AF_INET to force IPv4
+    hints.ai_socktype = SOCK_DGRAM;
+    hints.ai_flags = AI_PASSIVE; // use my IP
+
+    if ((rv = getaddrinfo(NULL, MYPORT, &hints, &servinfo)) != 0) {
+        fprintf(stderr, "getaddrinfo: %s\n", gai_strerror(rv));
+        return 1;
+    }
+
+    // loop through all the results and bind to the first we can
+    for(p = servinfo; p != NULL; p = p->ai_next) {
+        if ((sockfd = socket(p->ai_family, p->ai_socktype,
+                p->ai_protocol)) == -1) {
+            perror("listener: socket");
+            continue;
+        }
+
+        if (bind(sockfd, p->ai_addr, p->ai_addrlen) == -1) {
+            close(sockfd);
+            perror("listener: bind");
+            continue;
+        }
+
+        break;
+    }
+
+    if (p == NULL) {
+        fprintf(stderr, "listener: failed to bind socket\n");
+        return 2;
+    }
+
+    freeaddrinfo(servinfo);
+
+    printf("listener: waiting to recvfrom...\n");
+
+    addr_len = sizeof their_addr;
+    if ((numbytes = recvfrom(sockfd, buf, MAXBUFLEN-1 , 0,
+        (struct sockaddr *)&their_addr, &addr_len)) == -1) {
+        perror("recvfrom");
+        exit(1);
+    }
+
+    printf("listener: got packet from %s\n",
+        inet_ntop(their_addr.ss_family,
+            get_in_addr((struct sockaddr *)&their_addr),
+            s, sizeof s));
+    printf("listener: packet is %d bytes long\n", numbytes);
+    buf[numbytes] = '\0';
+    printf("listener: packet contains \"%s\"\n", buf);
+
+    close(sockfd);
+
+    return 0;
+}