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/* tcpclient.c
*
* TCP Client
* note: 'echo "hello" | nc -l -p 8080 localhost'
*
*
*/
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <string.h>
#include <sys/types.h>
#include <sys/uio.h>
#include <sys/socket.h>
#include <sys/select.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <netdb.h>
#define TARGET_MAX_SZ 1*1024*1024
static int sockfd;
static struct addrinfo *res;
static char *recv_buff;
void cleanup(void)
{
shutdown(sockfd, SHUT_RDWR);
close(sockfd);
if (recv_buff)
free(recv_buff);
/* free the linked list */
if (res)
freeaddrinfo(res);
}
int main(int argc, char **argv)
{
if (argc != 2)
{
fprintf(stderr, "usage: %s <host>\n", argv[0]);
exit(-1);
}
if (!strstr(argv[1], "http://"))
{
fprintf(stderr, "host needs to prefixed with \"http://\" protocol\n");
exit(-1);
}
/* grab the host and path from the URL */
char hoststr[100] = { 0 }, pathstr[100] = { 0 }, filestr[100] = { 0 };
sscanf(argv[1], "http://%[^/]/%s", hoststr, pathstr);
printf("host is: \"%s\"\n"
"path is: \"%s\"\n", hoststr, pathstr);
/* parse out a filestrname */
char *filepart = strrchr(pathstr, '/');
if (filepart && strlen(filepart + 1))
strcpy(filestr, filepart + 1);
else
strcpy(filestr, "index.html");
printf("file is: \"%s\"\n", filestr);
int ret;
/* prepare for getaddrinfo call */
struct addrinfo hints;
memset(&hints, 0, sizeof hints);
hints.ai_family = AF_UNSPEC;
hints.ai_socktype = SOCK_STREAM;
if ((ret = getaddrinfo(hoststr, "http", &hints, &res)) != 0)
{
fprintf(stderr, "getaddrinfo: %s\n", gai_strerror(ret));
exit(-1);
}
/* try all available IP addresses */
struct addrinfo *p;
char ipstr[INET6_ADDRSTRLEN];
void *addr;
char *ipver;
struct sockaddr_in *ipv4;
#if 0
struct sockaddr_in6 *ipv6;
#endif
printf("trying all available IP addresses for %s:\n", hoststr);
for (p = res; p != NULL; p = p->ai_next)
{
/* get the pointer to the address itself,
* different fields in IPv4 and IPv6 */
if (p->ai_family == AF_INET)
{ /* IPv4 */
ipv4 = (struct sockaddr_in *) p->ai_addr;
addr = &(ipv4->sin_addr);
ipver = "IPv4";
}
else
continue; /* ignore IPv6 for now */
#if 0
else
{ /* IPv6 */
ipv6 = (struct sockaddr_in6 *) p->ai_addr;
addr = &(ipv6->sin6_addr);
ipver = "IPv6";
}
#endif
/* convert the IP to a string and print it */
inet_ntop(p->ai_family, addr, ipstr, sizeof(ipstr));
printf("attempting to connect to %s: %s\n", ipstr, ipver);
/* create a socket */
if ((sockfd = socket(p->ai_family, p->ai_socktype, res->ai_protocol)) == -1)
{
perror("socket");
close(sockfd);
}
/* attempt to connect */
if (connect(sockfd, (struct sockaddr *) ipv4, sizeof(*ipv4)) == -1)
perror("connect");
else
{
printf("successfully connected\n");
break; /* break out of a loop, we got a connection */
}
}
if (!p)
{
fprintf(stderr, "failed to connect to a host\n");
exit(-1);
}
atexit(cleanup);
/* send http commands and receive data */
char request[128] = { 0 };
sprintf(request, "GET /%s HTTP/1.0\r\nHost: %s\r\n\r\n", pathstr, hoststr);
size_t request_len = strlen(request) * sizeof(char);
ret = send(sockfd, (void *) request, request_len, 0);
if (ret == -1)
{
perror("send");
exit(-1);
}
else if (ret != request_len)
{
fprintf(stderr, "sent less bytes than requested\n");
exit(-1);
}
/* receive until connection gets closed */
recv_buff = (char *) malloc(sizeof(char) * TARGET_MAX_SZ);
if (!recv_buff)
{
perror("malloc");
exit(-1);
}
size_t recv_len = 0;
do
{
ret = recv(sockfd, recv_buff + recv_len, TARGET_MAX_SZ - recv_len, 0);
if (ret == -1)
{
perror("recv");
exit(-1);
}
else if (ret == 0)
printf("remote host has closed the connection, received %lu bytes\n", recv_len);
recv_len += ret;
} while (ret > 0);
if (recv_len < 1)
{
fprintf(stderr, "did not receive any data from the host!\n");
exit(-1);
}
/* poke at http header and check for errors */
int code;
sscanf(recv_buff, "HTTP/1.%*[01] %d ", &code);
if (code == 200)
printf("received file\n");
else
{
printf("got an error code %d\n", code);
char errorline[100];
sscanf(recv_buff, "%[^\r\n]", errorline);
fprintf(stderr, "%s\n", errorline);
exit(-1);
}
/* save to disk */
char *buff_p = strstr(recv_buff, "\r\n\r\n"); /* seek past http header */
if (buff_p)
{
buff_p += 4;
FILE *fp = fopen(filestr, "w");
if (!fp)
{
perror("fopen");
exit(-1);
}
ret = fwrite(buff_p, recv_len - (buff_p - recv_buff), sizeof(char), fp);
fclose(fp);
}
else
fprintf(stderr, "could not seek past http header\n");
}
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