a simple imap client in C

simple-imap-client.c

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <string.h>

#include <sys/socket.h>
#include <sys/types.h>
#include <pthread.h>
#include "uv.h"

#define ThreadsNum 10

int open_cliendfd (char *host, int port)
{
  int fd;
  struct hostent *hp;
  struct sockaddr_in server_addr;
  
  fd = socket(AF_INET, SOCK_STREAM, 0);
  if (fd < 0)
    return -1;
  
  if ((hp = gethostbyname(host)) == NULL)
    return -2;
  
  bzero((char *) &server_addr, sizeof(server_addr));
  server_addr.sin_family = AF_INET;
  bcopy((char *)hp->h_addr_list[0],
        (char *)&server_addr.sin_addr.s_addr, hp->h_length);
  server_addr.sin_port = htons(port);
  
  if (connect(fd, (struct sockaddr *)&server_addr, sizeof(server_addr)) < 0)
    return -1;
  return fd;
}

char *imap_recv(int fd, size_t size) {
  size_t cursor = 0;
  int rc;
  
  char *buffer = (char *)malloc(size * sizeof(char));
  char *result = (char *)malloc(size * sizeof(char));
  
  while ((rc = (int)recv(fd, buffer, size, 0))) {
    
    if (rc == -1)
      continue;
    
    buffer[rc] = '\0';
    int len = (int)(sizeof(char)*(cursor++)*size) + rc;
    char *temp_str = buffer;
    char *temp_res = (char *)malloc(len);
    memcpy(temp_res, result, len);
    
    if (result != NULL) {
      strcat(temp_res, temp_str);
      memcpy(result, temp_res, strlen(temp_res)+1);
    } else {
      memcpy(result, buffer, strlen(buffer)+1);
    };
    //free(temp_res);
    
    // break
    if (rc < size) break;
  };
  
  return result;
}

void * thread_null(void* args_t);
int check_ok(char* str);

int main(int argc, char *argv[])
{
  printf("test\n");
  int i, rc; char x;
  
  pthread_t threads[ThreadsNum];

  for(i = 0; i < ThreadsNum; i++) {
    rc = pthread_create(&threads[i], NULL, thread_null, (void*)i);
    if (0 != rc) {
      fprintf(stderr, "pthread_create() failure\r\nMax pthread num is %d\r\n", i);
      exit(-1);
    } else {
      fprintf(stdout, "pthread_create() success\r\nCurrent pthread num is %d\r\n", i);
    }
  }
  fprintf(stdout, "Max pthread num is 65536\r\nYour system is power_full\r\n");
  scanf("blocking thread: %c", &x);
  //exit(0);
}

int check_ok(char* str)
{
  int len = (int)strlen(str), i;
  int is_ok = 0;
  for (i=0; i<len; i++) {
    if (i+4 > len) break;
    if (str[i] == 'O' && str[i+1] == 'K') {
      is_ok = 1;
      break;
    };
  };
  return is_ok;
}

void* thread_null(void* args_t)
{
  char login[50];
  snprintf(login, 50, "A2 LOGIN \"test%d\" \"ping55555\"\n", (int)args_t+1);
  
  int fd = open_cliendfd("imap.pingkit.com", 143);
  if (fd < 0) {
    fprintf(stdout, "fd = %d, open file failed\n", fd);
    return 0;
  } else {
    fprintf(stderr, "fd = %d\n", fd);
  };
  
  // init
  char *result = imap_recv(fd, 100);
  printf("len=%lu\n", strlen(result));
  
  char *buffers[6] = {
    "A1 CAPABILITY\n",
    login,
    "A3 CAPABILITY\n",
    "A4 ID (\"name\" \"inbox\" \"version\" \"1.0.0\" \"support-url\" \"http://yorkiefixer.me\")\n",
    "A5 SELECT \"INBOX\"\n",
    //"A6 FETCH *:* (UID ENVELOPE)\n"
    //"A7 LOGOUT\n"
  };
  
  int i = 0;
  do {
    printf("S: %s\n", result);
    if (i == 0) {
      printf("C: %s\n", buffers[i]);
      send(fd, buffers[i], strlen(buffers[i]), 0);
      i++;
      continue;
    }
    
    if (check_ok(result)) {
      if (i >= 5) {
        break;
      } else {
        printf("C: %s\n", buffers[i]);
        send(fd, buffers[i], strlen(buffers[i]), 0);
        i++;
      }
    }
  }
  while ((result = imap_recv(fd, 100)) || 1);
  
  int cursor = 10;
  while (1) {
    char msg[30];
    snprintf(msg, sizeof(msg), "A%d IDLE\n", cursor++);
    send(fd, msg, strlen(msg), 0);
    printf("C: %s\n", msg);

    // + idling...
    result = imap_recv(fd, 50);
    printf("S: %s\n", result);
    if (result[0] != '+')
      continue;

    // %d Exists...
  EXISTS:
    result = imap_recv(fd, 200);
    printf("S: %s\n", result);
    char seq[3];
    int k = 0;
    while (result[0] == '*') {
      if (result[2] < 48 || result[2] > 57)
        goto EXISTS;
        
      while (1) {
        printf("k=%d, chars=%c,%c\n", k, result[k], result[k+1]);
        if (result[k] >= 48 && result[k] <= 57 && result[k+1] == ' ') {
          if (result[k+2] != 'E') break;
          int start = 2;
          while (start <= k) {
            seq[start-2] = result[start];
            start += 1;
          };
          printf("seq=%s\n", seq); break;
        };
        k++;
      };
      send(fd, "DONE\n", 5, 0);
      printf("test%d comming a message\n", (int)args_t+1);
      printf("C: DONE\n");

      // OK IDLE terminated
      result = imap_recv(fd, 100);
      printf("S: %s\n", result);

      snprintf(msg, sizeof(msg), "A%d FETCH %s ALL\n", cursor++, seq);
      printf("C: %s\n", msg);
      send(fd, msg, strlen(msg), 0);

      // loop for FETCH OK Completed.
      while (1) {
        result = imap_recv(fd, 100);
        printf("S: %s\n", result);
        if (check_ok(result)) 
          break;
      };
      
      break;
    };
  }

  printf("done\n");
  return 0;
}