TCP_MD5SIG socketopt in Linux

tcpmd5_server6.c

/**
 * tcpmd5_server6.c: TCP_MD5SIG
 */
 
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <string.h>
 
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <netinet/tcp.h>
#include <netdb.h>
 
#include <arpa/inet.h>
 
#define BUFFERSZ 256
 
struct tcp_md5sig md5;
 
static inline void error(char *msg) {
    perror(msg);
    exit(1);
}
 
int main(int argc, char *argv[]) {
    int sockfd, newsockfd, portno;
    socklen_t clilen;
    char buffer[BUFFERSZ], *key, *s6ip, *sport, *c6ip, *cport;
    struct sockaddr_in6 serv_addr, saddr, cli_addr;
    int n, r;
    char client_addr_ipv6[100];
 
    if (argc != 6) {
        fprintf(stderr, "Usage: %s <server IPv6> <server port> "
                "<client IPv6> <client port> <MD5 key>\n",
                argv[0]);
        return -1;
    }
 
    s6ip = argv[1];
    sport = argv[2];
    c6ip = argv[3];
    cport = argv[4];
    key = argv[5];
 
    printf("\nIPv6 TCP Server (TCP_MD5SIG) ...\n");
 
    //Sockets Layer Call: socket()
    sockfd = socket(AF_INET6, SOCK_STREAM, 0);
    if (sockfd < 0)
        error("ERROR opening socket");
 
    bzero((char *) &serv_addr, sizeof(serv_addr));
    portno = atoi(sport);
    serv_addr.sin6_family = AF_INET6;
    if(inet_pton(AF_INET6, s6ip, &serv_addr.sin6_addr) <= 0)
        error("ERROR on inet_pton");
    serv_addr.sin6_port = htons(portno);
 
    //Sockets Layer Call: bind()
    if (bind(sockfd, (struct sockaddr *) &serv_addr,
                sizeof(serv_addr)) < 0)
        error("ERROR on binding");
 
    // Client sockaddr_in6 for TCPMD5_SIG
    memset(&saddr, '0', sizeof(saddr));
    saddr.sin6_family = AF_INET6;
    if(inet_pton(AF_INET6, c6ip, &saddr.sin6_addr)<=0)
        error("ERROR on inet_pton");
    saddr.sin6_port = htons(atoi(cport));
    //memcpy(&md5.tcpm_addr, &saddr, sizeof(saddr));
    md5.tcpm_addr = *(struct sockaddr_storage *) &saddr;
    strcpy(md5.tcpm_key, key);
    md5.tcpm_keylen = strlen(key);
    if ((r = setsockopt(sockfd, IPPROTO_TCP, TCP_MD5SIG,
                    &md5, sizeof(md5))) < 0)
        error("listen setsockopt TCP_MD5SIG");
 
    //Sockets Layer Call: listen()
    listen(sockfd, 5);
    clilen = sizeof(cli_addr);
 
    //Sockets Layer Call: accept()
    newsockfd = accept(sockfd, (struct sockaddr *) &cli_addr, &clilen);
    if (newsockfd < 0)
        error("ERROR on accept");
 
    //Sockets Layer Call: inet_ntop()
    inet_ntop(AF_INET6, &(cli_addr.sin6_addr),client_addr_ipv6, 100);
    printf("Incoming connection from client having IPv6 address: %s\n",
            client_addr_ipv6);
 
    memset(buffer,0, BUFFERSZ);
 
    //Sockets Layer Call: recv()
    n = recv(newsockfd, buffer, BUFFERSZ-1, 0);
    if (n < 0)
        error("ERROR reading from socket");
 
    printf("Message from client: %s\n", buffer);
 
    //Sockets Layer Call: send()
    n = send(newsockfd, "Server got your message",
            strlen("Server got your message"), 0);
    if (n < 0)
        error("ERROR writing to socket");
 
    //Sockets Layer Call: close()
    close(sockfd);
    close(newsockfd);
 
    return 0;
}

tcpmd5_client6.c

/**
 * tcpmd5_client6.c: TCP_MD5SIG
 */
 
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <string.h>
 
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <netinet/tcp.h>
#include <netdb.h>
 
#define BUFFERSZ 256
 
static inline void error(char *msg) {
    perror(msg);
    exit(0);
}
 
struct tcp_md5sig md5;
 
int main(int argc, char *argv[]) {
    int sockfd, portno, n, r;
    struct sockaddr_in6 cl_addr, serv_addr;
    struct hostent *server;
    char buffer[BUFFERSZ] = "This is a string from client!";
    char *key, *s6ip, *sport, *c6ip, *cport;
 
    if (argc != 6) {
        fprintf(stderr, "Usage: %s <server IPv6> <server port> "
                "<client IPv6> <client port> <MD5 key>\n",
                argv[0]);
        return -1;
    }
 
    s6ip = argv[1];
    sport = argv[2];
    c6ip = argv[3];
    cport = argv[4];
    key = argv[5];
    printf("\nIPv6 TCP Client Started...\n");
 
    //Sockets Layer Call: socket()
    sockfd = socket(AF_INET6, SOCK_STREAM, 0);
    if (sockfd < 0)
        error("ERROR opening socket");
 
    //Sockets Layer Call: bind()
    memset((char *) &cl_addr, 0, sizeof(cl_addr));
    cl_addr.sin6_family = AF_INET6;
    if(inet_pton(AF_INET6, c6ip, &cl_addr.sin6_addr)<=0)
        error("ERROR on inet_pton");
    cl_addr.sin6_port = htons(atoi(cport));
    if (bind(sockfd, (struct sockaddr *) &cl_addr, 
                sizeof(cl_addr)) < 0)
        error("ERROR on binding");
 
    memset((char *) &serv_addr, 0, sizeof(serv_addr));
    serv_addr.sin6_family = AF_INET6;
    if(inet_pton(AF_INET6, s6ip,
                &serv_addr.sin6_addr)<=0)
        error("ERROR on inet_pton");
    serv_addr.sin6_port = htons(atoi(sport));
    memcpy(&md5.tcpm_addr, &serv_addr, sizeof(serv_addr));
    strcpy(md5.tcpm_key, key);
    md5.tcpm_keylen = strlen(key);
    if ((r = setsockopt(sockfd, IPPROTO_TCP, TCP_MD5SIG,
                    &md5, sizeof(md5))) < 0)
        error("listen setsockopt TCP_MD5SIG");
 
    //Sockets Layer Call: connect()
    if (connect(sockfd, (struct sockaddr *) &serv_addr, 
                sizeof(serv_addr)) < 0)
        error("ERROR connecting");
 
    //Sockets Layer Call: send()
    n = send(sockfd, buffer, strlen(buffer)+1, 0);
    if (n < 0)
        error("ERROR writing to socket");
 
    memset(buffer, 0, BUFFERSZ);
 
    //Sockets Layer Call: recv()
    n = recv(sockfd, buffer, BUFFERSZ-1, 0);
    if (n < 0)
        error("ERROR reading from socket");
    printf("Message from server: %s\n", buffer);
 
    //Sockets Layer Call: close()
    close(sockfd);
 
    return 0;
}