Add simple server application

.gitignore

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

simple-server/build/Makefile

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

simple-server/src/main.c

+#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 SERVER_PORT "50000"
+#define BUFFER_SIZE 1024
+
+static 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() {
+
+	int status;
+	int sockfd;
+	struct addrinfo hints, *servinfo, *servinfo_it;
+
+	int bytes_received = 0;
+
+	struct sockaddr_storage client_addr;
+	socklen_t addr_len;
+	char client_addr_str[INET6_ADDRSTRLEN];
+	
+	char buf[BUFFER_SIZE];
+
+	memset(&hints, 0, sizeof hints);
+	hints.ai_family = AF_UNSPEC;
+	hints.ai_socktype = SOCK_DGRAM;
+	hints.ai_flags = AI_PASSIVE;
+
+	status = getaddrinfo(NULL, SERVER_PORT, &hints, &servinfo);
+	if( status != 0 ) {
+		fprintf(stderr, "getaddrinfo: %s\n", gai_strerror(status));
+		printf("getaddrinfo: %s\n", gai_strerror(status));
+		return 1;
+	}
+
+	for(servinfo_it = servinfo; servinfo_it; 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;
+		}
+
+		if( bind(sockfd, servinfo_it->ai_addr, servinfo_it->ai_addrlen) == -1 ) {
+			close(sockfd);
+			printf("Bind error, continuing...\n");
+			continue;
+		}
+		break;
+	}
+
+	freeaddrinfo(servinfo);
+
+	addr_len = sizeof client_addr;
+
+	printf("waiting to recvfrom...\n");
+
+	while(1) {
+
+		if( (bytes_received = recvfrom(sockfd, buf, BUFFER_SIZE-1, 0,
+					      (struct sockaddr *)&client_addr, &addr_len)) == -1) {
+			printf("recvfrom error\n");
+			return 2;
+		}
+
+		inet_ntop(client_addr.ss_family,
+			  get_in_addr((struct sockaddr *)&client_addr),
+			  client_addr_str, sizeof(client_addr_str));
+		buf[bytes_received] = '\0';
+
+		printf("got packet from %s: %s (%d long)\n", client_addr_str, buf, bytes_received);
+	}
+
+	close(sockfd);
+
+	return 0;
+}