/*
* httpread - Manage reading file(s) from HTTP/TCP socket
* Author: Ted Merrill
* Copyright 2008 Atheros Communications
*
* This software may be distributed under the terms of the BSD license.
* See README for more details.
*
* The files are buffered via internal callbacks from eloop, then presented to
* an application callback routine when completely read into memory. May also
* be used if no file is expected but just to get the header, including HTTP
* replies (e.g. HTTP/1.1 200 OK etc.).
*
* This does not attempt to be an optimally efficient implementation, but does
* attempt to be of reasonably small size and memory consumption; assuming that
* only small files are to be read. A maximum file size is provided by
* application and enforced.
*
* It is assumed that the application does not expect any of the following:
* -- transfer encoding other than chunked
* -- trailer fields
* It is assumed that, even if the other side requested that the connection be
* kept open, that we will close it (thus HTTP messages sent by application
* should have the connection closed field); this is allowed by HTTP/1.1 and
* simplifies things for us.
*
* Other limitations:
* -- HTTP header may not exceed a hard-coded size.
*
* Notes:
* This code would be massively simpler without some of the new features of
* HTTP/1.1, especially chunked data.
*/
#include "includes.h"
#include "common.h"
#include "eloop.h"
#include "httpread.h"
/* Tunable parameters */
#define HTTPREAD_READBUF_SIZE 1024 /* read in chunks of this size */
#define HTTPREAD_HEADER_MAX_SIZE 4096 /* max allowed for headers */
#define HTTPREAD_BODYBUF_DELTA 4096 /* increase allocation by this */
/* control instance -- actual definition (opaque to application)
*/
struct httpread {
/* information from creation */
int sd; /* descriptor of TCP socket to read from */
void (*cb)(struct httpread *handle, void *cookie,
enum httpread_event e); /* call on event */
void *cookie; /* pass to callback */
int max_bytes; /* maximum file size else abort it */
int timeout_seconds; /* 0 or total duration timeout period */
/* dynamically used information follows */
int got_hdr; /* nonzero when header is finalized */
char hdr[HTTPREAD_HEADER_MAX_SIZE+1]; /* headers stored here */
int hdr_nbytes;
enum httpread_hdr_type hdr_type;
int version; /* 1 if we've seen 1.1 */
int reply_code; /* for type REPLY, e.g. 200 for HTTP/1.1 200 OK */
int got_content_length; /* true if we know content length for sure */
int content_length; /* body length, iff got_content_length */
int chunked; /* nonzero for chunked data */
char *uri;
int got_body; /* nonzero when body is finalized */
char *body;
int body_nbytes;
int body_alloc_nbytes; /* amount allocated */
int got_file; /* here when we are done */
/* The following apply if data is chunked: */
int in_chunk_data; /* 0=in/at header, 1=in the data or tail*/
int chunk_start; /* offset in body of chunk hdr or data */
int chunk_size; /* data of chunk (not hdr or ending CRLF)*/
int in_trailer; /* in header fields after data (chunked only)*/
enum trailer_state {
trailer_line_begin = 0,
trailer_empty_cr, /* empty line + CR */
trailer_nonempty,
trailer_nonempty_cr,
} trailer_state;
};
/* Check words for equality, where words consist of graphical characters
* delimited by whitespace
* Returns nonzero if "equal" doing case insensitive comparison.
*/
static int word_eq(char *s1, char *s2)
{
int c1;
int c2;
int end1 = 0;
int end2 = 0;
for (;;) {
c1 = *s1++;
c2 = *s2++;
if (isalpha(c1) && isupper(c1))
c1 = tolower(c1);
if (isalpha(c2) && isupper(c2))
c2 = tolower(c2);
end1 = !isgraph(c1);
end2 = !isgraph(c2);
if (end1 || end2 || c1 != c2)
break;
}
return end1 && end2; /* reached end of both words? */
}
static void httpread_timeout_handler(void *eloop_data, void *user_ctx);
/* httpread_destroy -- if h is non-NULL, clean up
* This must eventually be called by the application following
* call of the application's callback and may be called
* earlier if desired.
*/
void httpread_destroy(struct httpread *h)
{
wpa_printf(MSG_DEBUG, "httpread_destroy(%p)", h);
if (!h)
return;
eloop_cancel_timeout(httpread_timeout_handler, NULL, h);
eloop_unregister_sock(h->sd, EVENT_TYPE_READ);
os_free(h->body);
os_free(h->uri);
os_memset(h, 0, sizeof(*h)); /* aid debugging */
h->sd = -1; /* aid debugging */
os_free(h);
}
/* httpread_timeout_handler -- called on excessive total duration
*/
static void httpread_timeout_handler(void *eloop_data, void *user_ctx)
{
struct httpread *h = user_ctx;
wpa_printf(MSG_DEBUG, "httpread timeout (%p)", h);
(*h->cb)(h, h->cookie, HTTPREAD_EVENT_TIMEOUT);
}
/* Analyze options only so far as is needed to correctly obtain the file.
* The application can look at the raw header to find other options.
*/
static int httpread_hdr_option_analyze(
struct httpread *h,
char *hbp /* pointer to current line in header buffer */
)
{
if (word_eq(hbp, "CONTENT-LENGTH:")) {
while (isgraph(*hbp))
hbp++;
while (*hbp == ' ' || *hbp == '\t')
hbp++;
if (!isdigit(*hbp))
return -1;
h->content_length = atol(hbp);
if (h->content_length < 0 || h->content_length > h->max_bytes) {
wpa_printf(MSG_DEBUG,
"httpread: Unacceptable Content-Length %d",
h->content_length);
return -1;
}
h->got_content_length = 1;
return 0;
}
if (word_eq(hbp, "TRANSFER_ENCODING:") ||
word_eq(hbp, "TRANSFER-ENCODING:")) {
while (isgraph(*hbp))
hbp++;
while (*hbp == ' ' || *hbp == '\t')
hbp++;
/* There should (?) be no encodings of interest
* other than chunked...
*/
if (word_eq(hbp, "CHUNKED")) {
h->chunked = 1;
h->in_chunk_data = 0;
/* ignore possible ;<parameters> */
}
return 0;
}
/* skip anything we don't know, which is a lot */
return 0;
}
static int httpread_hdr_analyze(struct httpread *h)
{
char *hbp = h->hdr; /* pointer into h->hdr */
int standard_first_line = 1;
/* First line is special */
h->hdr_type = HTTPREAD_HDR_TYPE_UNKNOWN;
if (!isgraph(*hbp))
goto bad;
if (os_strncmp(hbp, "HTTP/", 5) == 0) {
h->hdr_type = HTTPREAD_HDR_TYPE_REPLY;
standard_first_line = 0;
hbp += 5;
if (hbp[0] == '1' && hbp[1] == '.' &&
isdigit(hbp[2]) && hbp[2] != '0')
h->version = 1;
while (isgraph(*hbp))
hbp++;
while (*hbp == ' ' || *hbp == '\t')
hbp++;
if (!isdigit(*hbp))
goto bad;
h->reply_code = atol(hbp);
} else if (word_eq(hbp, "GET"))
h->hdr_type = HTTPREAD_HDR_TYPE_GET;
else if (word_eq(hbp, "HEAD"))
h->hdr_type = HTTPREAD_HDR_TYPE_HEAD;
else if (word_eq(hbp, "POST"))
h->hdr_type = HTTPREAD_HDR_TYPE_POST;
else if (word_eq(hbp, "PUT"))
h->hdr_type = HTTPREAD_HDR_TYPE_PUT;
else if (word_eq(hbp, "DELETE"))
h->hdr_type = HTTPREAD_HDR_TYPE_DELETE;
else if (word_eq(hbp, "TRACE"))
h->hdr_type = HTTPREAD_HDR_TYPE_TRACE;
else if (word_eq(hbp, "CONNECT"))
h->hdr_type = HTTPREAD_HDR_TYPE_CONNECT;
else if (word_eq(hbp, "NOTIFY"))
h->hdr_type = HTTPREAD_HDR_TYPE_NOTIFY;
else if (word_eq(hbp, "M-SEARCH"))
h->hdr_type = HTTPREAD_HDR_TYPE_M_SEARCH;
else if (word_eq(hbp, "M-POST"))
h->hdr_type = HTTPREAD_HDR_TYPE_M_POST;
else if (word_eq(hbp, "SUBSCRIBE"))
h->hdr_type = HTTPREAD_HDR_TYPE_SUBSCRIBE;
else if (word_eq(hbp, "UNSUBSCRIBE"))
h->hdr_type = HTTPREAD_HDR_TYPE_UNSUBSCRIBE;
else {
}
if (standard_first_line) {
char *rawuri;
char *uri;
/* skip type */
while (isgraph(*hbp))
hbp++;
while (*hbp == ' ' || *hbp == '\t')
hbp++;
/* parse uri.
* Find length, allocate memory for translated
* copy, then translate by changing %<hex><hex>
* into represented value.
*/
rawuri = hbp;
while (isgraph(*hbp))
hbp++;
h->uri = os_malloc((hbp - rawuri) + 1);
if (h->uri == NULL)
goto bad;
uri = h->uri;
while (rawuri < hbp) {
int c = *rawuri;
if (c == '%' &&
isxdigit(rawuri[1]) && isxdigit(rawuri[2])) {
*uri++ = hex2byte(rawuri + 1);
rawuri += 3;
} else {
*uri++ = c;
rawuri++;
}
}
*uri = 0; /* null terminate */
while (isgraph(*hbp))
hbp++;
while (*hbp == ' ' || *hbp == '\t')
hbp++;
/* get version */
if (0 == strncmp(hbp, "HTTP/", 5)) {
hbp += 5;
if (hbp[0] == '1' && hbp[1] == '.' &&
isdigit(hbp[2]) && hbp[2] != '0')
h->version = 1;
}
}
/* skip rest of line */
while (*hbp)
if (*hbp++ == '\n')
break;
/* Remainder of lines are options, in any order;
* or empty line to terminate
*/
for (;;) {
/* Empty line to terminate */
if (hbp[0] == '\n' ||
(hbp[0] == '\r' && hbp[1] == '\n'))
break;
if (!isgraph(*hbp))
goto bad;
if (httpread_hdr_option_analyze(h, hbp))
goto bad;
/* skip line */
while (*hbp)
if (*hbp++ == '\n')
break;
}
/* chunked overrides content-length always */
if (h->chunked)
h->got_content_length = 0;
/* For some types, we should not try to read a body
* This is in addition to the application determining
* that we should not read a body.
*/
switch (h->hdr_type) {
case HTTPREAD_HDR_TYPE_REPLY:
/* Some codes can have a body and some not.
* For now, just assume that any other than 200
* do not...
*/
if (h->reply_code != 200)
h->max_bytes = 0;
break;
case HTTPREAD_HDR_TYPE_GET:
case HTTPREAD_HDR_TYPE_HEAD:
/* in practice it appears that it is assumed
* that GETs have a body length of 0... ?
*/
if (h->chunked == 0 && h->got_content_length == 0)
h->max_bytes = 0;
break;
case HTTPREAD_HDR_TYPE_POST:
case HTTPREAD_HDR_TYPE_PUT:
case HTTPREAD_HDR_TYPE_DELETE:
case HTTPREAD_HDR_TYPE_TRACE:
case HTTPREAD_HDR_TYPE_CONNECT:
case HTTPREAD_HDR_TYPE_NOTIFY:
case HTTPREAD_HDR_TYPE_M_SEARCH:
case HTTPREAD_HDR_TYPE_M_POST:
case HTTPREAD_HDR_TYPE_SUBSCRIBE:
case HTTPREAD_HDR_TYPE_UNSUBSCRIBE:
default:
break;
}
return 0;
bad:
/* Error */
return -1;
}
/* httpread_read_handler -- called when socket ready to read
*
* Note: any extra data we read past end of transmitted file is ignored;
* if we were to support keeping connections open for multiple files then
* this would have to be addressed.
*/
static void httpread_read_handler(int sd, void *eloop_ctx, void *sock_ctx)
{
struct httpread *h = sock_ctx;
int nread;
char *rbp; /* pointer into read buffer */
char *hbp; /* pointer into header buffer */
char *bbp; /* pointer into body buffer */
char readbuf[HTTPREAD_READBUF_SIZE]; /* temp use to read into */
/* read some at a time, then search for the interal
* boundaries between header and data and etc.
*/
wpa_printf(MSG_DEBUG, "httpread: Trying to read more data(%p)", h);
nread = read(h->sd, readbuf, sizeof(readbuf));
if (nread < 0) {
wpa_printf(MSG_DEBUG, "httpread failed: %s", strerror(errno));
goto bad;
}
wpa_hexdump_ascii(MSG_MSGDUMP, "httpread - read", readbuf, nread);
if (nread == 0) {
/* end of transmission... this may be normal
* or may be an error... in some cases we can't
* tell which so we must assume it is normal then.
*/
if (!h->got_hdr) {
/* Must at least have completed header */
wpa_printf(MSG_DEBUG, "httpread premature eof(%p)", h);
goto bad;
}
if (h->chunked || h->got_content_length) {
/* Premature EOF; e.g. dropped connection */
wpa_printf(MSG_DEBUG,
"httpread premature eof(%p) %d/%d",
h, h->body_nbytes,
h->content_length);
goto bad;
}
/* No explicit length, hopefully we have all the data
* although dropped connections can cause false
* end
*/
wpa_printf(MSG_DEBUG, "httpread ok eof(%p)", h);
h->got_body = 1;
goto got_file;
}
rbp = readbuf;
/* Header consists of text lines (terminated by both CR and LF)
* and an empty line (CR LF only).
*/
if (!h->got_hdr) {
hbp = h->hdr + h->hdr_nbytes;
/* add to headers until:
* -- we run out of data in read buffer
* -- or, we run out of header buffer room
* -- or, we get double CRLF in headers
*/
for (;;) {
if (nread == 0)
goto get_more;
if (h->hdr_nbytes == HTTPREAD_HEADER_MAX_SIZE) {
wpa_printf(MSG_DEBUG,
"httpread: Too long header");
goto bad;
}
*hbp++ = *rbp++;
nread--;
h->hdr_nbytes++;
if (h->hdr_nbytes >= 4 &&
hbp[-1] == '\n' &&
hbp[-2] == '\r' &&
hbp[-3] == '\n' &&
hbp[-4] == '\r' ) {
h->got_hdr = 1;
*hbp = 0; /* null terminate */
break;
}
}
/* here we've just finished reading the header */
if (httpread_hdr_analyze(h)) {
wpa_printf(MSG_DEBUG, "httpread bad hdr(%p)", h);
goto bad;
}
if (h->max_bytes == 0) {
wpa_printf(MSG_DEBUG, "httpread no body hdr end(%p)",
h);
goto got_file;
}
if (h->got_content_length && h->content_length == 0) {
wpa_printf(MSG_DEBUG,
"httpread zero content length(%p)", h);
goto got_file;
}
}
/* Certain types of requests never have data and so
* must be specially recognized.
*/
if (!os_strncasecmp(h->hdr, "SUBSCRIBE", 9) ||
!os_strncasecmp(h->hdr, "UNSUBSCRIBE", 11) ||
!os_strncasecmp(h->hdr, "HEAD", 4) ||
!os_strncasecmp(h->hdr, "GET", 3)) {
if (!h->got_body) {
wpa_printf(MSG_DEBUG, "httpread NO BODY for sp. type");
}
h->got_body = 1;
goto got_file;
}
/* Data can be just plain binary data, or if "chunked"
* consists of chunks each with a header, ending with
* an ending header.
*/
if (nread == 0)
goto get_more;
if (!h->got_body) {
/* Here to get (more of) body */
/* ensure we have enough room for worst case for body
* plus a null termination character
*/
if (h->body_alloc_nbytes < (h->body_nbytes + nread + 1)) {
char *new_body;
int new_alloc_nbytes;
if (h->body_nbytes >= h->max_bytes) {
wpa_printf(MSG_DEBUG,
"httpread: body_nbytes=%d >= max_bytes=%d",
h->body_nbytes, h->max_bytes);
goto bad;
}
new_alloc_nbytes = h->body_alloc_nbytes +
HTTPREAD_BODYBUF_DELTA;
/* For content-length case, the first time
* through we allocate the whole amount
* we need.
*/
if (h->got_content_length &&
new_alloc_nbytes < (h->content_length + 1))
new_alloc_nbytes = h->content_length + 1;
if (new_alloc_nbytes < h->body_alloc_nbytes ||
new_alloc_nbytes > h->max_bytes) {
wpa_printf(MSG_DEBUG,
"httpread: Unacceptable body length %d",
new_alloc_nbytes);
goto bad;
}
if ((new_body = os_realloc(h->body, new_alloc_nbytes))
== NULL) {
wpa_printf(MSG_DEBUG,
"httpread: Failed to reallocate buffer (len=%d)",
new_alloc_nbytes);
goto bad;
}
h->body = new_body;
h->body_alloc_nbytes = new_alloc_nbytes;
}
/* add bytes */
bbp = h->body + h->body_nbytes;
for (;;) {
int ncopy;
/* See if we need to stop */
if (h->chunked && h->in_chunk_data == 0) {
/* in chunk header */
char *cbp = h->body + h->chunk_start;
if (bbp-cbp >= 2 && bbp[-2] == '\r' &&
bbp[-1] == '\n') {
/* end of chunk hdr line */
/* hdr line consists solely
* of a hex numeral and CFLF
*/
if (!isxdigit(*cbp)) {
wpa_printf(MSG_DEBUG,
"httpread: Unexpected chunk header value (not a hex digit)");
goto bad;
}
h->chunk_size = strtoul(cbp, NULL, 16);
if (h->chunk_size < 0 ||
h->chunk_size > h->max_bytes) {
wpa_printf(MSG_DEBUG,
"httpread: Invalid chunk size %d",
h->chunk_size);
goto bad;
}
/* throw away chunk header
* so we have only real data
*/
h->body_nbytes = h->chunk_start;
bbp = cbp;
if (h->chunk_size == 0) {
/* end of chunking */
/* trailer follows */
h->in_trailer = 1;
wpa_printf(MSG_DEBUG,
"httpread end chunks(%p)",
h);
break;
}
h->in_chunk_data = 1;
/* leave chunk_start alone */
}
} else if (h->chunked) {
/* in chunk data */
if ((h->body_nbytes - h->chunk_start) ==
(h->chunk_size + 2)) {
/* end of chunk reached,
* new chunk starts
*/
/* check chunk ended w/ CRLF
* which we'll throw away
*/
if (bbp[-1] == '\n' &&
bbp[-2] == '\r') {
} else {
wpa_printf(MSG_DEBUG,
"httpread: Invalid chunk end");
goto bad;
}
h->body_nbytes -= 2;
bbp -= 2;
h->chunk_start = h->body_nbytes;
h->in_chunk_data = 0;
h->chunk_size = 0; /* just in case */
}
} else if (h->got_content_length &&
h->body_nbytes >= h->content_length) {
h->got_body = 1;
wpa_printf(MSG_DEBUG,
"httpread got content(%p)", h);
goto got_file;
}
if (nread <= 0)
break;
/* Now transfer. Optimize using memcpy where we can. */
if (h->chunked && h->in_chunk_data) {
/* copy up to remainder of chunk data
* plus the required CR+LF at end
*/
ncopy = (h->chunk_start + h->chunk_size + 2) -
h->body_nbytes;
} else if (h->chunked) {
/*in chunk header -- don't optimize */
*bbp++ = *rbp++;
nread--;
h->body_nbytes++;
continue;
} else if (h->got_content_length) {
ncopy = h->content_length - h->body_nbytes;
} else {
ncopy = nread;
}
/* Note: should never be 0 */
if (ncopy < 0) {
wpa_printf(MSG_DEBUG,
"httpread: Invalid ncopy=%d", ncopy);
goto bad;
}
if (ncopy > nread)
ncopy = nread;
os_memcpy(bbp, rbp, ncopy);
bbp += ncopy;
h->body_nbytes += ncopy;
rbp += ncopy;
nread -= ncopy;
} /* body copy loop */
} /* !got_body */
if (h->chunked && h->in_trailer) {
/* If "chunked" then there is always a trailer,
* consisting of zero or more non-empty lines
* ending with CR LF and then an empty line w/ CR LF.
* We do NOT support trailers except to skip them --
* this is supported (generally) by the http spec.
*/
for (;;) {
int c;
if (nread <= 0)
break;
c = *rbp++;
nread--;
switch (h->trailer_state) {
case trailer_line_begin:
if (c == '\r')
h->trailer_state = trailer_empty_cr;
else
h->trailer_state = trailer_nonempty;
break;
case trailer_empty_cr:
/* end empty line */
if (c == '\n') {
h->trailer_state = trailer_line_begin;
h->in_trailer = 0;
wpa_printf(MSG_DEBUG,
"httpread got content(%p)",
h);
h->got_body = 1;
goto got_file;
}
h->trailer_state = trailer_nonempty;
break;
case trailer_nonempty:
if (c == '\r')
h->trailer_state = trailer_nonempty_cr;
break;
case trailer_nonempty_cr:
if (c == '\n')
h->trailer_state = trailer_line_begin;
else
h->trailer_state = trailer_nonempty;
break;
}
}
}
goto get_more;
bad:
/* Error */
wpa_printf(MSG_DEBUG, "httpread read/parse failure (%p)", h);
(*h->cb)(h, h->cookie, HTTPREAD_EVENT_ERROR);
return;
get_more:
wpa_printf(MSG_DEBUG, "httpread: get more (%p)", h);
return;
got_file:
wpa_printf(MSG_DEBUG, "httpread got file %d bytes type %d",
h->body_nbytes, h->hdr_type);
wpa_hexdump_ascii(MSG_MSGDUMP, "httpread: body",
h->body, h->body_nbytes);
/* Null terminate for convenience of some applications */
if (h->body)
h->body[h->body_nbytes] = 0; /* null terminate */
h->got_file = 1;
/* Assume that we do NOT support keeping connection alive,
* and just in case somehow we don't get destroyed right away,
* unregister now.
*/
eloop_unregister_sock(h->sd, EVENT_TYPE_READ);
/* The application can destroy us whenever they feel like...
* cancel timeout.
*/
eloop_cancel_timeout(httpread_timeout_handler, NULL, h);
(*h->cb)(h, h->cookie, HTTPREAD_EVENT_FILE_READY);
}
/* httpread_create -- start a new reading session making use of eloop.
* The new instance will use the socket descriptor for reading (until
* it gets a file and not after) but will not close the socket, even
* when the instance is destroyed (the application must do that).
* Return NULL on error.
*
* Provided that httpread_create successfully returns a handle,
* the callback fnc is called to handle httpread_event events.
* The caller should do destroy on any errors or unknown events.
*
* Pass max_bytes == 0 to not read body at all (required for e.g.
* reply to HEAD request).
*/
struct httpread * httpread_create(
int sd, /* descriptor of TCP socket to read from */
void (*cb)(struct httpread *handle, void *cookie,
enum httpread_event e), /* call on event */
void *cookie, /* pass to callback */
int max_bytes, /* maximum body size else abort it */
int timeout_seconds /* 0; or total duration timeout period */
)
{
struct httpread *h = NULL;
h = os_zalloc(sizeof(*h));
if (h == NULL)
goto fail;
h->sd = sd;
h->cb = cb;
h->cookie = cookie;
h->max_bytes = max_bytes;
h->timeout_seconds = timeout_seconds;
if (timeout_seconds > 0 &&
eloop_register_timeout(timeout_seconds, 0,
httpread_timeout_handler, NULL, h)) {
/* No way to recover (from malloc failure) */
goto fail;
}
if (eloop_register_sock(sd, EVENT_TYPE_READ, httpread_read_handler,
NULL, h)) {
/* No way to recover (from malloc failure) */
goto fail;
}
return h;
fail:
/* Error */
httpread_destroy(h);
return NULL;
}
/* httpread_hdr_type_get -- When file is ready, returns header type. */
enum httpread_hdr_type httpread_hdr_type_get(struct httpread *h)
{
return h->hdr_type;
}
/* httpread_uri_get -- When file is ready, uri_get returns (translated) URI
* or possibly NULL (which would be an error).
*/
char * httpread_uri_get(struct httpread *h)
{
return h->uri;
}
/* httpread_reply_code_get -- When reply is ready, returns reply code */
int httpread_reply_code_get(struct httpread *h)
{
return h->reply_code;
}
/* httpread_length_get -- When file is ready, returns file length. */
int httpread_length_get(struct httpread *h)
{
return h->body_nbytes;
}
/* httpread_data_get -- When file is ready, returns file content
* with null byte appened.
* Might return NULL in some error condition.
*/
void * httpread_data_get(struct httpread *h)
{
return h->body ? h->body : "";
}
/* httpread_hdr_get -- When file is ready, returns header content
* with null byte appended.
* Might return NULL in some error condition.
*/
char * httpread_hdr_get(struct httpread *h)
{
return h->hdr;
}
/* httpread_hdr_line_get -- When file is ready, returns pointer
* to line within header content matching the given tag
* (after the tag itself and any spaces/tabs).
*
* The tag should end with a colon for reliable matching.
*
* If not found, returns NULL;
*/
char * httpread_hdr_line_get(struct httpread *h, const char *tag)
{
int tag_len = os_strlen(tag);
char *hdr = h->hdr;
hdr = os_strchr(hdr, '\n');
if (hdr == NULL)
return NULL;
hdr++;
for (;;) {
if (!os_strncasecmp(hdr, tag, tag_len)) {
hdr += tag_len;
while (*hdr == ' ' || *hdr == '\t')
hdr++;
return hdr;
}
hdr = os_strchr(hdr, '\n');
if (hdr == NULL)
return NULL;
hdr++;
}
}