Arduino ESP8266 tcp server receives gibberish

Development Boards Arduino
2

For what it’s worth, here’s the tcp client code. It seems to be working fine. I’ve tested it with another server.

 * Copyright Mark Watson 1999. Open Source Software License.
 * Note: derived from NLPserver client example.
 * See www.markwatson.com/opensource/opensource.htm for all
 * of the natural language server (NLPserver) source code.
 *
 * Updated by Ray Depew, December 2017
 */

#include <stdio.h>
#include <stdlib.h> // exit()
#include <string.h> // memset()
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <unistd.h> // close()
#include <netdb.h>

char * host_name = "192.168.0.131"; // localhost
// char * host_name = "127.0.0.1"; // localhost
int port = 3230;

void main(int argc, char *argv[])
{
  char buf[8192];
  char message[256];
  int socket_descriptor;
  struct sockaddr_in pin;
  struct hostent *server_host_name;

  char * str = "A default test string";

  if (argc < 2) {
    printf("Usage: 'test \"Any test string\"\n");
    printf("We will send a default test string.\n");
  } else {
    str = argv[1];
  }

  if ((server_host_name = gethostbyname(host_name)) == 0) {
    perror("Error resolving local host\n");
    exit(1);
  }

  memset(&pin, 0, sizeof(pin));
  pin.sin_family = AF_INET;
  pin.sin_addr.s_addr = htonl(INADDR_ANY);
  pin.sin_addr.s_addr = ((struct in_addr *)(server_host_name->h_addr))->s_addr;
  pin.sin_port = htons(port);

  if ((socket_descriptor = socket(AF_INET, SOCK_STREAM, 0)) == -1) {
    perror("Error opening socket\n");
    exit(1);
  }

  if (connect(socket_descriptor, (void *)&pin, sizeof(pin)) == -1) {
    perror("Error connecting to socket\n");
    exit(1);
  }

  printf("Sending message %s to server...\n", str);

  /* FIXME: Delete after debug */
  int message_len = strlen(str);
  printf("(%d bytes)\n", message_len);

  if (send(socket_descriptor, &str, strlen(str), 0) == -1) {
    perror("Error in send");
    exit(1);
  }

  printf("..sent message.. wait for response...\n");

  if (recv(socket_descriptor, buf, 8192, 0) == -1) {
    perror("Error in receiving response from server\n");
    exit(1);
  }

  printf("\nResponse from server:\n%s\n", buf);

  close(socket_descriptor);
}