gistfile1.c

#include <sys/types.h>
#include <sys/socket.h>
#include <sys/stat.h>
#include <sys/un.h>
#include <sys/time.h>
#include <netinet/in.h>
#include <netinet/tcp.h>
#include <arpa/inet.h>
#include <unistd.h>
#include <fcntl.h>
#include <string.h>
#include <netdb.h>
#include <errno.h>
#include <stdarg.h>
#include <stdio.h>

#define ANET_CONNECT_NONE 0
#define ANET_CONNECT_NONBLOCK 1
#define ANET_OK 0
#define ANET_ERR -1
#define ANET_ERR_LEN 256

static void anetSetError(char *err, const char *fmt, ...)
{
    va_list ap;

    if (!err) return;
    va_start(ap, fmt);
    vsnprintf(err, ANET_ERR_LEN, fmt, ap);
    va_end(ap);
}

static int anetSetReuseAddr(char *err, int fd) {
    int yes = 1;
    /* Make sure connection-intensive things like the redis benckmark
     * will be able to close/open sockets a zillion of times */
    if (setsockopt(fd, SOL_SOCKET, SO_REUSEADDR, &yes, sizeof(yes)) == -1) {
        anetSetError(err, "setsockopt SO_REUSEADDR: %s", strerror(errno));
        return ANET_ERR;
    }
    return ANET_OK;
}

int anetSetBlock(char *err, int fd, int non_block) {
    int flags;

    /* Set the socket blocking (if non_block is zero) or non-blocking.
     * Note that fcntl(2) for F_GETFL and F_SETFL can't be
     * interrupted by a signal. */
    if ((flags = fcntl(fd, F_GETFL)) == -1) {
        anetSetError(err, "fcntl(F_GETFL): %s", strerror(errno));
        return ANET_ERR;
    }

    if (non_block)
        flags |= O_NONBLOCK;
    else
        flags &= ~O_NONBLOCK;

    if (fcntl(fd, F_SETFL, flags) == -1) {
        anetSetError(err, "fcntl(F_SETFL,O_NONBLOCK): %s", strerror(errno));
        return ANET_ERR;
    }
    return ANET_OK;
}

int anetNonBlock(char *err, int fd) {
    return anetSetBlock(err,fd,1);
}

static int anetTcpGenericConnect(char *err, char *addr, int port,
                                 char *source_addr, int flags)
{
    int s = ANET_ERR, rv;
    char portstr[6];  /* strlen("65535") + 1; */
    struct addrinfo hints, *servinfo, *bservinfo, *p, *b;

    snprintf(portstr,sizeof(portstr),"%d",port);
    memset(&hints,0,sizeof(hints));
    hints.ai_family = AF_UNSPEC;
    hints.ai_socktype = SOCK_STREAM;

    if ((rv = getaddrinfo(addr,portstr,&hints,&servinfo)) != 0) {
        anetSetError(err, "%s", gai_strerror(rv));
        return ANET_ERR;
    }
    for (p = servinfo; p != NULL; p = p->ai_next) {
        /* Try to create the socket and to connect it.
         * If we fail in the socket() call, or on connect(), we retry with
         * the next entry in servinfo. */
        printf("Creating socket\n");
        if ((s = socket(p->ai_family,p->ai_socktype,p->ai_protocol)) == -1)
            continue;
        if (anetSetReuseAddr(err,s) == ANET_ERR) goto error;
        if (flags & ANET_CONNECT_NONBLOCK && anetNonBlock(err,s) != ANET_OK)
            goto error;
        if (source_addr) {
            int bound = 0;
            /* Using getaddrinfo saves us from self-determining IPv4 vs IPv6 */
            if ((rv = getaddrinfo(source_addr, NULL, &hints, &bservinfo)) != 0)
            {
                anetSetError(err, "%s", gai_strerror(rv));
                goto end;
            }
            for (b = bservinfo; b != NULL; b = b->ai_next) {
                int enabled = 1;
                setsockopt(s, IPPROTO_IP, IP_TRANSPARENT, &enabled, sizeof(enabled));

                if (bind(s,b->ai_addr,b->ai_addrlen) != -1) {
                    bound = 1;
                    break;
                }
            }
            freeaddrinfo(bservinfo);
            if (!bound) {
                anetSetError(err, "bind: %s", strerror(errno));
                goto end;
            }
        }
        if (connect(s,p->ai_addr,p->ai_addrlen) == -1) {
            printf(".. and failed\n");
            /* If the socket is non-blocking, it is ok for connect() to
             * return an EINPROGRESS error here. */
            if (errno == EINPROGRESS && flags & ANET_CONNECT_NONBLOCK)
                goto end;
            close(s);
            s = ANET_ERR;
            continue;
        }

        /* If we ended an iteration of the for loop without errors, we
         * have a connected socket. Let's return to the caller. */
        goto end;
    }
    if (p == NULL)
        anetSetError(err, "creating socket: %s", strerror(errno));

error:
    if (s != ANET_ERR) {
        close(s);
        s = ANET_ERR;
    }
end:
    freeaddrinfo(servinfo);
    return s;
}

int main(char **argc, char **argv)
{
  char err[1000];
  char *addr = "10.134.82.199";
  int port = 18000;
  char *source_addr = "127.0.0.1";
  int ret = anetTcpGenericConnect(err,addr,port,source_addr,ANET_CONNECT_NONBLOCK);
  if(strlen(err) > 0) {
    printf("There was an error: %s\n", err);
  }
  return ret;
}