Add simple client application

.gitignore

+*.o
+*.d
+simple-client/build/main

simple-client/build/Makefile

+PROG = main
+SRCDIR = ../src
+
+SRCS  = main.c
+SRCS += getip.c
+SRCS += send_packet.c
+
+OBJS = $(SRCS:%.c=%.o)
+
+CFLAGS = -O1 -g -Wall -Werror -Wextra
+CFLAGS += -MD -MP
+CFLAGS += -I $(SRCDIR)
+CFLAGS += -std=gnu99
+
+vpath %.c $(SRCDIR)
+
+
+$(PROG): $(OBJS)
+	$(CC) $(LDFLAGS) $^ -o $@
+
+-include $(subst .c,.d,$(SRCS))
+
+run: $(PROG)
+	./$^
+
+clean:
+	$(RM) $(OBJS) $(PROG) $(subst .c,.d,$(SRCS))
+
+.PHONY: clean

simple-client/src/getip.c

+#include "getip.h"
+
+#include <ifaddrs.h>
+#include <stdio.h>
+#include <string.h>
+#include <sys/types.h>
+#include <netinet/in.h>
+#include <arpa/inet.h>
+
+void print_ifs(void) {
+  struct ifaddrs* ifap;
+
+  getifaddrs(&ifap);
+
+  printf("Interfaces:\n\n");
+
+  for (struct ifaddrs* cur_ifap = ifap; cur_ifap;
+       cur_ifap = cur_ifap->ifa_next) {
+    printf("%s, ", cur_ifap->ifa_name);
+
+    void * addr;
+    char * ipver;
+    char ipstr[INET6_ADDRSTRLEN];
+    struct sockaddr * sa = cur_ifap->ifa_addr;
+
+    if( sa->sa_family == AF_INET ) { // IPV4
+      struct sockaddr_in * ipv4 = (struct sockaddr_in *) sa;
+      addr = &(ipv4->sin_addr);
+      ipver = "IPv4";
+    } else {
+      struct sockaddr_in6 * ipv6 = (struct sockaddr_in6 *) sa;
+      addr = &(ipv6->sin6_addr);
+      ipver = "IPv6";
+    }
+
+    inet_ntop(sa->sa_family, addr, ipstr, sizeof ipstr);
+    printf("  %s: %s\n", ipver, ipstr);
+  }
+
+  freeifaddrs(ifap);
+}

simple-client/src/getip.h

+#ifndef GETIP_H
+#define GETIP_H
+
+void print_ifs(void);
+
+#endif

simple-client/src/main.c

+#include <stdio.h>
+
+#include "getip.h"
+#include "send_packet.h"
+
+int main() {
+
+  for(int i = 0; i < 100; i++)
+    send_udp_packet();
+
+  return 0;
+}

simple-client/src/send_packet.c

+#include "send_packet.h"
+
+/*
+#include <netinet/in.h>
+#include <stdio.h>
+#include <string.h>
+#include <sys/socket.h>
+#include <sys/types.h>
+*/
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include <errno.h>
+#include <string.h>
+#include <netdb.h>
+#include <sys/types.h>
+#include <netinet/in.h>
+#include <sys/socket.h>
+
+#include <arpa/inet.h>
+
+#define SERVER_IP "192.168.0.100"
+#define SERVER_PORT "50000"
+
+int send_udp_packet(void) {
+  int status;
+  int sockfd;
+
+  struct addrinfo hints, *servinfo, *servinfo_it;
+
+  char msg[1024] = "hello";
+  int bytes_sent = 0;
+  int msg_len = strlen(msg);
+
+  memset(&hints, 0, sizeof hints);
+  hints.ai_family = AF_UNSPEC;
+  hints.ai_socktype = SOCK_DGRAM;
+
+  status = getaddrinfo(SERVER_IP, SERVER_PORT, &hints, &servinfo);
+  if( status != 0 ) {
+    fprintf(stderr, "getaddrinfo: %s\n", gai_strerror(status));
+    printf("getaddrinfo error, exiting...\n");
+    return 1;
+  }
+
+  for(servinfo_it = servinfo; servinfo_it != NULL; servinfo_it = servinfo_it->ai_next) {
+    sockfd = socket(servinfo->ai_family, servinfo->ai_socktype, servinfo->ai_protocol);
+    if(sockfd == -1) {
+      printf("Socket error, continuing...\n");
+      continue;
+    }
+    break;
+  }
+
+  if(servinfo_it == NULL) {
+    fprintf(stderr, "Failed to create socket\n");
+    printf("Failed to create socket\n");
+    return 2;
+  }
+
+  while (bytes_sent < msg_len) {
+    bytes_sent += sendto(sockfd, msg + bytes_sent, strlen(msg), 0, servinfo->ai_addr,
+                         servinfo->ai_addrlen);
+  }
+
+  freeaddrinfo(servinfo);
+
+  printf("Sent %d bytes to %s\n", bytes_sent, SERVER_IP);
+  close(sockfd);
+  return 0;
+}

simple-client/src/send_packet.h

+#ifndef SEND_PACKET_H
+#define SEND_PACKET_H
+
+int send_udp_packet(void);
+
+#endif