busybox/networking/wget.c

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/* vi: set sw=4 ts=4: */
/*
* wget - retrieve a file using HTTP
*
* Chip Rosenthal
* Covad Communications
* <chip@laserlink.net>
*/
#include "internal.h"
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <ctype.h>
#include <string.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <netdb.h>
void parse_url(char *url, char **uri_host, int *uri_port, char **uri_path);
FILE *open_socket(char *host, int port);
char *gethdr(char *buf, size_t bufsiz, FILE *fp, int *istrunc);
int wget_main(int argc, char **argv)
{
FILE *sfp; /* socket to web server */
char *uri_host, *uri_path; /* parsed from command line url */
int uri_port;
char *s, buf[512];
int n;
char *fname_out = NULL; /* where to direct output (-O) */
int do_continue = 0; /* continue a prev transfer (-c) */
long beg_range = 0L; /* range at which continue begins */
int got_clen = 0; /* got content-length: from server */
long clen = 1L; /* the content length */
/*
* Crack command line.
*/
while ((n = getopt(argc, argv, "cO:")) != EOF) {
switch (n) {
case 'c':
++do_continue;
break;
case 'O':
fname_out = (strcmp(optarg, "-") == 0 ? NULL : optarg);
break;
default:
usage(wget_usage);
}
}
if (do_continue && !fname_out)
fatalError("wget: cannot specify continue (-c) without a filename (-O)\n");
if (argc - optind != 1)
usage(wget_usage);
/*
* Parse url into components.
*/
parse_url(argv[optind], &uri_host, &uri_port, &uri_path);
/*
* Open socket to server.
*/
sfp = open_socket(uri_host, uri_port);
/*
* Open the output stream.
*/
if (fname_out != NULL) {
if (freopen(fname_out, (do_continue ? "a" : "w"), stdout) == NULL)
fatalError("wget: freopen(%s): %s\n", fname_out, strerror(errno));
}
/*
* Determine where to start transfer.
*/
if (do_continue) {
struct stat sbuf;
if (fstat(fileno(stdout), &sbuf) < 0)
fatalError("wget: fstat(): %s\n", strerror(errno));
if (sbuf.st_size > 0)
beg_range = sbuf.st_size;
else
do_continue = 0;
}
/*
* Send HTTP request.
*/
fprintf(sfp, "GET %s HTTP/1.1\r\nHost: %s\r\n", uri_path, uri_host);
if (do_continue)
fprintf(sfp, "Range: bytes=%ld-\r\n", beg_range);
fputs("Connection: close\r\n\r\n", sfp);
/*
* Retrieve HTTP response line and check for "200" status code.
*/
if (fgets(buf, sizeof(buf), sfp) == NULL)
fatalError("wget: no response from server\n");
for (s = buf ; *s != '\0' && !isspace(*s) ; ++s)
;
for ( ; isspace(*s) ; ++s)
;
switch (atoi(s)) {
case 200:
if (!do_continue)
break;
fatalError("wget: cannot continue - server does not properly support ranges\n");
case 206:
if (do_continue)
break;
/*FALLTHRU*/
default:
fatalError("wget: server returned error: %s", buf);
}
/*
* Retrieve HTTP headers.
*/
while ((s = gethdr(buf, sizeof(buf), sfp, &n)) != NULL) {
if (strcmp(buf, "content-length") == 0) {
clen = atol(s);
got_clen = 1;
continue;
}
if (strcmp(buf, "transfer-encoding") == 0) {
fatalError("wget: i do not do transfer encodings, server wants to do: %s\n", s);
continue;
}
}
/*
* Retrieve HTTP body.
*/
while (clen > 0 && (n = fread(buf, 1, sizeof(buf), sfp)) > 0) {
fwrite(buf, 1, n, stdout);
if (got_clen)
clen -= n;
}
if (n == 0 && ferror(sfp))
fatalError("wget: network read error: %s", strerror(errno));
exit(0);
}
void parse_url(char *url, char **uri_host, int *uri_port, char **uri_path)
{
char *s, *h;
*uri_port = 80;
if (strncmp(url, "http://", 7) != 0)
fatalError("wget: not an http url: %s\n", url);
/* pull the host portion to the front of the buffer */
for (s = url, h = url+7 ; *h != '/' ; ++h) {
if (*h == '\0')
fatalError("wget: cannot parse url: %s\n", url);
if (*h == ':') {
*uri_port = atoi(h+1);
*h = '\0';
}
*s++ = *h;
}
*s = '\0';
*uri_host = url;
*uri_path = h;
}
FILE *open_socket(char *host, int port)
{
struct sockaddr_in sin;
struct hostent *hp;
int fd;
FILE *fp;
memzero(&sin, sizeof(sin));
sin.sin_family = AF_INET;
if ((hp = (struct hostent *) gethostbyname(host)) == NULL)
fatalError("wget: cannot resolve %s\n", host);
memcpy(&sin.sin_addr, hp->h_addr_list[0], hp->h_length);
sin.sin_port = htons(port);
/*
* Get the server onto a stdio stream.
*/
if ((fd = socket(AF_INET, SOCK_STREAM, 0)) < 0)
fatalError("wget: socket(): %s\n", strerror(errno));
if (connect(fd, (struct sockaddr *) &sin, sizeof(sin)) < 0)
fatalError("wget: connect(%s): %s\n", host, strerror(errno));
if ((fp = fdopen(fd, "r+")) == NULL)
fatalError("wget: fdopen(): %s\n", strerror(errno));
return fp;
}
char *gethdr(char *buf, size_t bufsiz, FILE *fp, int *istrunc)
{
char *s, *hdrval;
int c;
*istrunc = 0;
/* retrieve header line */
if (fgets(buf, bufsiz, fp) == NULL)
return NULL;
/* see if we are at the end of the headers */
for (s = buf ; *s == '\r' ; ++s)
;
if (s[0] == '\n')
return NULL;
/* convert the header name to lower case */
for (s = buf ; isalnum(*s) || *s == '-' ; ++s)
*s = tolower(*s);
/* verify we are at the end of the header name */
if (*s != ':')
fatalError("wget: bad header line: %s\n", buf);
/* locate the start of the header value */
for (*s++ = '\0' ; *s == ' ' || *s == '\t' ; ++s)
;
hdrval = s;
/* locate the end of header */
while (*s != '\0' && *s != '\r' && *s != '\n')
++s;
/* end of header found */
if (*s != '\0') {
*s = '\0';
return hdrval;
}
/* Rats! The buffer isn't big enough to hold the entire header value. */
while (c = getc(fp), c != EOF && c != '\n')
;
*istrunc = 1;
return hdrval;
}
/*
Local Variables:
c-file-style: "linux"
c-basic-offset: 4
tab-width: 4
End:
*/