aboutsummaryrefslogtreecommitdiff
path: root/networking/wget.c
blob: 58801ee47885115e4aeeab24859ebe9312c9584d (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
/* vi: set sw=4 ts=4: */
/*
 * wget - retrieve a file using HTTP
 *
 * Chip Rosenthal
 * Covad Communications
 * <chip@laserlink.net>
 */

#include "busybox.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:
*/