please help me to solve this network class assignment

#include <stdio.h> #include <stdlib.h> #include <string.h> #include <getopt.h> #include "a2.h" #include "a3.h" #include "a4.h" #define DEFAULT_PORT 12345 typedef struct cfg { long port; char *iface; char *server; char *mcast; FILE *fstream; int use_udp; int use_rudp; } cfg_t; /* * If we are a server, launch the appropriate methods to handle server * functionality based on the configuration arguments. */ void run_server(cfg_t *cfg) { fprintf(stderr, "Hello, I'm a server with no purpose...goodbye\n"); /* For example, if cfg->udp is true, then call the server UDP handler */ } /* * If we are a client, launch the appropriate methods to handle client * functionality based on the configuration arguments. */ void run_client(cfg_t *cfg) { fprintf(stderr, "Hello, I'm a client with no purpose...goodbye\n"); /* For example, if cfg->udp is true, then call the client UDP handler */ } void usage(const char *argv0) { printf("Usage:\n"); printf(" %s start a server and wait for connection\n", argv0); printf(" %s <host> connect to server at <host>\n", argv0); printf("\n"); printf("Options:\n"); printf(" -p, --port=<port> listen on/connect to port <port>\n"); printf(" -i, --iface=<dev> listen on interface <dev>\n"); printf(" -f, --file=<filename> file to read/write\n"); printf(" -u, --udp use UDP (default TCP)\n"); printf(" -r, --rudp use RUDP (1=stopwait, 2=gobackN)\n"); printf(" -m, --mcast=<addr> multicast address\n"); } int main(int argc, char **argv) { int c; char *fname = NULL; /* The configuration structure for netster */ cfg_t cfg = { .port = DEFAULT_PORT, /* which port to use */ .iface = NULL, /* which interface to use */ .server = NULL, /* the server to connect to */ .mcast = NULL, /* the multicast group to use */ .fstream = NULL, /* the open file stream if fname given */ .use_udp = 0, /* should we use UDP (default TCP) */ .use_rudp = 0, /* should we use RUDP (default TCP) */ }; static struct option long_options[] = { { .name = "port", .has_arg = 1, .val = 'p' }, { .name = "iface", .has_arg = 1, .val = 'i' }, { .name = "mcast", .has_arg = 1, .val = 'm' }, { .name = "file", .has_arg = 1, .val = 'f' }, { .name = "udp", .has_arg = 0, .val = 'u' }, { .name = "rudp", .has_arg = 1, .val = 'r' }, { 0 } }; while (1) { c = getopt_long(argc, argv, "p:i:m:f:r:u", long_options, NULL); if (c == -1) break; switch (c) { case 'p': cfg.port = strtol(optarg, NULL, 0); if (cfg.port < 0 || cfg.port > 65535) { usage(argv[0]); return 1; } break; case 'i': cfg.iface = strdup(optarg); break; case 'u': cfg.use_udp = 1; break; case 'r': cfg.use_rudp = atoi(optarg); break; case 'm': cfg.mcast = strdup(optarg); break; case 'f': fname = strdup(optarg); break; default: usage(argv[0]); return 1; break; } } if (optind == argc - 1) cfg.server = strdup(argv[optind]); /* open the file if specified */ if (fname) { const char *mode = (cfg.server) ? "r" : "w+"; cfg.fstream = fopen(fname, mode); if (!cfg.fstream) { perror("fopen: "); exit(1); } } /* Here we decide if we started as a server or client! */ if (cfg.server) run_client(&cfg); else run_server(&cfg); if (fname && cfg.fstream) { fclose(cfg.fstream); } return 0; }