get url info

urlinfo.c

#include <arpa/inet.h>
#include <stdio.h>
#include <stdlib.h>
#include <netdb.h>
#include <netinet/in.h>
#include <sys/socket.h>

#define case_return(ENUM_VALUE) case ENUM_VALUE: return #ENUM_VALUE;

const char* get_family(int f) {
    switch(f) {
        case_return(AF_INET);
        case_return(AF_INET6);
        case_return(AF_UNSPEC);
        default: return "Neither ipv4 not ipv6 address family";
    }
}

const char* get_socktype(int s) {
    switch(s) {
        case_return(SOCK_DGRAM);
        case_return(SOCK_STREAM);
        case_return(SOCK_RAW);
        default: return "Neither raw nor dgram nor stream socket";
    }
}

const char* get_proto(int p) {
    switch(p) {
        case_return(IPPROTO_IP);
        case_return(IPPROTO_ICMP);
        case_return(IPPROTO_TCP);
        case_return(IPPROTO_UDP);
        default: return "other proto";
    }
}

static inline struct sockaddr_in* sa_ptr_to_in_ptr(struct sockaddr* sa) { return (struct sockaddr_in*)sa; }
static inline struct sockaddr_in6* sa_ptr_to_in6_ptr(struct sockaddr* sa) { return (struct sockaddr_in6*)sa; }

#define as_in4(SA) _Generic((SA), struct sockaddr*: sa_ptr_to_in_ptr)(SA)
#define as_in6(SA) _Generic((SA), struct sockaddr*: sa_ptr_to_in6_ptr)(SA)

#define sin_inet_ntop(SA, BUF, BUFSZ) inet_ntop(AF_INET, &(as_in4(SA)->sin_addr), BUF, BUFSZ)
#define sin6_inet_ntop(SA, BUF, BUFSZ) inet_ntop(AF_INET6, &(as_in6(SA)->sin6_addr), BUF, BUFSZ)

void print_sockaddr_row(struct sockaddr* sa, char* const sep) {
    char buf[INET6_ADDRSTRLEN];
    char const* addr = 0x0;
    in_port_t port;

    switch(sa->sa_family) {
        case AF_INET:   { 
            addr = sin_inet_ntop(sa, buf, sizeof(buf));
            port = as_in4(sa)->sin_port;
            break;
        } 
        case AF_INET6:  { 
            addr = sin6_inet_ntop(sa, buf, sizeof(buf));
            port = as_in6(sa)->sin6_port;
            break;
        } 
        case AF_UNSPEC: { printf("AF_UNSPEC"); } 
        default: { fprintf(stderr, "unsupported sockaddr family"); return; }
    }

    if (addr) {
        printf("%-40s%s%d", addr, sep, port);
    } else {
        fprintf(stderr, "inet_ntop error");
    }
}

void print_addrinfo_row(const char* url, struct addrinfo* ai, char* const sep) {
    printf("%s%s" "0x%x%s" "%-8s%s" "%s%s" "%s%s" "%d%s" "%s%s",
           url, sep,
           ai->ai_flags, sep,
           get_family(ai->ai_family), sep,
           get_socktype(ai->ai_socktype), sep,
           get_proto(ai->ai_protocol), sep,
           ai->ai_addrlen, sep,
           ai->ai_canonname, sep
   );
   print_sockaddr_row(ai->ai_addr, sep);
   puts("");
}


void print_addrinfo_header(char* const sep) {
    printf("url\t%s" "flags%s" "familiy   %s" "socktype%s" "protocol%s"
            "addrlen%s" "cname%s" "address                                   %s"
            "port\n",
            sep, sep, sep, sep ,sep ,sep ,sep, sep
  );
}

int print_info(const char* url, char* const sep) {
    struct addrinfo* result;
    int error = getaddrinfo(url, NULL, NULL, &result);
    if (error != 0) {   
        fprintf(stderr, "%s: error in getaddrinfo: %s\n", url, gai_strerror(error));
        return EXIT_FAILURE;
    }   

    for (struct addrinfo* res = result; res != NULL; res = res->ai_next) {
        print_addrinfo_row(url, res, sep);
    }   

    freeaddrinfo(result);
    return EXIT_SUCCESS;
}


int main(int argc, char* argv[]) {
    char* const sep = "\t";
    print_addrinfo_header(sep);
    for (int i = 1; i < argc; ++i) {
        print_info(argv[i], sep);
    }
}