REORG: spoe: Move low-level encoding/decoding functions in dedicated header file

So, it will be easier to anyone to develop external services using these
functions.

SPOA example has been updated accordingly.
diff --git a/src/flt_spoe.c b/src/flt_spoe.c
index 2ef924f..8156287 100644
--- a/src/flt_spoe.c
+++ b/src/flt_spoe.c
@@ -34,6 +34,7 @@
 #include <proto/sample.h>
 #include <proto/session.h>
 #include <proto/signal.h>
+#include <proto/spoe.h>
 #include <proto/stream.h>
 #include <proto/stream_interface.h>
 #include <proto/task.h>
@@ -346,392 +347,6 @@
 	return vsn;
 }
 
-/* Encode the integer <i> into a varint (variable-length integer). The encoded
- * value is copied in <*buf>. Here is the encoding format:
- *
- *        0 <= X < 240        : 1 byte  (7.875 bits)  [ XXXX XXXX ]
- *      240 <= X < 2288       : 2 bytes (11 bits)     [ 1111 XXXX ] [ 0XXX XXXX ]
- *     2288 <= X < 264432     : 3 bytes (18 bits)     [ 1111 XXXX ] [ 1XXX XXXX ]   [ 0XXX XXXX ]
- *   264432 <= X < 33818864   : 4 bytes (25 bits)     [ 1111 XXXX ] [ 1XXX XXXX ]*2 [ 0XXX XXXX ]
- * 33818864 <= X < 4328786160 : 5 bytes (32 bits)     [ 1111 XXXX ] [ 1XXX XXXX ]*3 [ 0XXX XXXX ]
- * ...
- *
- * On success, it returns the number of written bytes and <*buf> is moved after
- * the encoded value. Otherwise, it returns -1. */
-static int
-spoe_encode_varint(uint64_t i, char **buf, char *end)
-{
-	unsigned char *p = (unsigned char *)*buf;
-	int r;
-
-	if (p >= (unsigned char *)end)
-		return -1;
-
-	if (i < 240) {
-		*p++ = i;
-		*buf = (char *)p;
-		return 1;
-	}
-
-	*p++ = (unsigned char)i | 240;
-	i = (i - 240) >> 4;
-	while (i >= 128) {
-		if (p >= (unsigned char *)end)
-			return -1;
-		*p++ = (unsigned char)i | 128;
-		i = (i - 128) >> 7;
-	}
-
-	if (p >= (unsigned char *)end)
-		return -1;
-	*p++ = (unsigned char)i;
-
-	r    = ((char *)p - *buf);
-	*buf = (char *)p;
-	return r;
-}
-
-/* Decode a varint from <*buf> and save the decoded value in <*i>. See
- * 'spoe_encode_varint' for details about varint.
- * On success, it returns the number of read bytes and <*buf> is moved after the
- * varint. Otherwise, it returns -1. */
-static int
-spoe_decode_varint(char **buf, char *end, uint64_t *i)
-{
-	unsigned char *p = (unsigned char *)*buf;
-	int r;
-
-	if (p >= (unsigned char *)end)
-		return -1;
-
-	*i = *p++;
-	if (*i < 240) {
-		*buf = (char *)p;
-		return 1;
-	}
-
-	r = 4;
-	do {
-		if (p >= (unsigned char *)end)
-			return -1;
-		*i += (uint64_t)*p << r;
-		r  += 7;
-	} while (*p++ >= 128);
-
-	r    = ((char *)p - *buf);
-	*buf = (char *)p;
-	return r;
-}
-
-/* Encode a buffer. Its length <len> is encoded as a varint, followed by a copy
- * of <str>. It must have enough space in <*buf> to encode the buffer, else an
- * error is triggered.
- * On success, it returns <len> and <*buf> is moved after the encoded value. If
- * an error occurred, it returns -1. */
-static int
-spoe_encode_buffer(const char *str, size_t len, char **buf, char *end)
-{
-	char *p = *buf;
-	int   ret;
-
-	if (p >= end)
-		return -1;
-
-	if (!len) {
-		*p++ = 0;
-		*buf = p;
-		return 0;
-	}
-
-	ret = spoe_encode_varint(len, &p, end);
-	if (ret == -1 || p + len > end)
-		return -1;
-
-	memcpy(p, str, len);
-	*buf = p + len;
-	return len;
-}
-
-/* Encode a buffer, possibly partially. It does the same thing than
- * 'spoe_encode_buffer', but if there is not enough space, it does not fail.
- * On success, it returns the number of copied bytes and <*buf> is moved after
- * the encoded value. If an error occured, it returns -1. */
-static int
-spoe_encode_frag_buffer(const char *str, size_t len, char **buf, char *end)
-{
-	char *p = *buf;
-	int   ret;
-
-	if (p >= end)
-		return -1;
-
-	if (!len) {
-		*p++ = 0;
-		*buf = p;
-		return 0;
-	}
-
-	ret = spoe_encode_varint(len, &p, end);
-	if (ret == -1 || p >= end)
-		return -1;
-
-	ret = (p+len < end) ? len : (end - p);
-	memcpy(p, str, ret);
-	*buf = p + ret;
-	return ret;
-}
-
-/* Decode a buffer. The buffer length is decoded and saved in <*len>. <*str>
- * points on the first byte of the buffer.
- * On success, it returns the buffer length and <*buf> is moved after the
- * encoded buffer. Otherwise, it returns -1. */
-static int
-spoe_decode_buffer(char **buf, char *end, char **str, size_t *len)
-{
-	char    *p = *buf;
-	uint64_t sz;
-	int      ret;
-
-	*str = NULL;
-	*len = 0;
-
-	ret = spoe_decode_varint(&p, end, &sz);
-	if (ret == -1 || p + sz > end)
-		return -1;
-
-	*str = p;
-	*len = sz;
-	*buf = p + sz;
-	return sz;
-}
-
-/* Encode a typed data using value in <smp>. On success, it returns the number
- * of copied bytes and <*buf> is moved after the encoded value. If an error
- * occured, it returns -1.
- *
- * If the value is too big to be encoded, depending on its type, then encoding
- * failed or the value is partially encoded. Only strings and binaries can be
- * partially encoded. In this case, the offset <*off> is updated to known how
- * many bytes has been encoded. If <*off> is zero at the end, it means that all
- * data has been encoded. */
-static int
-spoe_encode_data(struct sample *smp, unsigned int *off, char **buf, char *end)
-{
-	char *p = *buf;
-	int   ret;
-
-	if (p >= end)
-		return -1;
-
-	if (smp == NULL) {
-		*p++ = SPOE_DATA_T_NULL;
-		goto end;
-	}
-
-	switch (smp->data.type) {
-		case SMP_T_BOOL:
-			*p    = SPOE_DATA_T_BOOL;
-			*p++ |= ((!smp->data.u.sint) ? SPOE_DATA_FL_FALSE : SPOE_DATA_FL_TRUE);
-			break;
-
-		case SMP_T_SINT:
-			*p++ = SPOE_DATA_T_INT64;
-			if (spoe_encode_varint(smp->data.u.sint, &p, end) == -1)
-				return -1;
-			break;
-
-		case SMP_T_IPV4:
-			if (p + 5 > end)
-				return -1;
-			*p++ = SPOE_DATA_T_IPV4;
-			memcpy(p, &smp->data.u.ipv4, 4);
-			p += 4;
-			break;
-
-		case SMP_T_IPV6:
-			if (p + 17 > end)
-				return -1;
-			*p++ = SPOE_DATA_T_IPV6;
-			memcpy(p, &smp->data.u.ipv6, 16);
-			p += 16;
-			break;
-
-		case SMP_T_STR:
-		case SMP_T_BIN: {
-			struct chunk *chk = &smp->data.u.str;
-
-			/* Here, we need to know if the sample has already been
-			 * partially encoded. If yes, we only need to encode the
-			 * remaining, <*off> reprensenting the number of bytes
-			 * already encoded. */
-			if (!*off) {
-				/* First evaluation of the sample : encode the
-				 * type (string or binary), the buffer length
-				 * (as a varint) and at least 1 byte of the
-				 * buffer. */
-				struct chunk *chk = &smp->data.u.str;
-
-				*p++ = (smp->data.type == SMP_T_STR)
-					? SPOE_DATA_T_STR
-					: SPOE_DATA_T_BIN;
-				ret = spoe_encode_frag_buffer(chk->str, chk->len, &p, end);
-				if (ret == -1)
-					return -1;
-			}
-			else {
-				/* The sample has been fragmented, encode remaining data */
-				ret = MIN(chk->len - *off, end - p);
-				memcpy(p, chk->str + *off, ret);
-				p += ret;
-			}
-			/* Now update <*off> */
-			if (ret + *off != chk->len)
-				*off += ret;
-			else
-				*off = 0;
-			break;
-		}
-
-		case SMP_T_METH:
-			*p++ = SPOE_DATA_T_STR;
-			if (smp->data.u.meth.meth != HTTP_METH_OTHER) {
-				const struct http_method_name *meth =
-					&http_known_methods[smp->data.u.meth.meth];
-
-				if (spoe_encode_buffer(meth->name, meth->len, &p, end) == -1)
-					return -1;
-			}
-			else {
-				struct chunk *meth = &smp->data.u.meth.str;
-
-				if (spoe_encode_buffer(meth->str, meth->len, &p, end) == -1)
-					return -1;
-			}
-			break;
-
-		default:
-			*p++ = SPOE_DATA_T_NULL;
-			break;
-	}
-
-  end:
-	ret  = (p - *buf);
-	*buf = p;
-	return ret;
-}
-
-/* Skip a typed data. If an error occurred, -1 is returned, otherwise the number
- * of skipped bytes is returned and the <*buf> is moved after skipped data.
- *
- * A types data is composed of a type (1 byte) and corresponding data:
- *  - boolean: non additional data (0 bytes)
- *  - integers: a variable-length integer (see spoe_decode_varint)
- *  - ipv4: 4 bytes
- *  - ipv6: 16 bytes
- *  - binary and string: a buffer prefixed by its size, a variable-length
- *    integer (see spoe_decode_buffer) */
-static int
-spoe_skip_data(char **buf, char *end)
-{
-	char    *str, *p = *buf;
-	int      type, ret;
-	size_t   sz;
-	uint64_t v;
-
-	if (p >= end)
-		return -1;
-
-	type = *p++;
-	switch (type & SPOE_DATA_T_MASK) {
-		case SPOE_DATA_T_BOOL:
-			break;
-		case SPOE_DATA_T_INT32:
-		case SPOE_DATA_T_INT64:
-		case SPOE_DATA_T_UINT32:
-		case SPOE_DATA_T_UINT64:
-			if (spoe_decode_varint(&p, end, &v) == -1)
-				return -1;
-			break;
-		case SPOE_DATA_T_IPV4:
-			if (p+4 > end)
-				return -1;
-			p += 4;
-			break;
-		case SPOE_DATA_T_IPV6:
-			if (p+16 > end)
-				return -1;
-			p += 16;
-			break;
-		case SPOE_DATA_T_STR:
-		case SPOE_DATA_T_BIN:
-			/* All the buffer must be skipped */
-			if (spoe_decode_buffer(&p, end, &str, &sz) == -1)
-				return -1;
-			break;
-	}
-
-	ret  = (p - *buf);
-	*buf = p;
-	return ret;
-}
-
-/* Decode a typed data and fill <smp>. If an error occurred, -1 is returned,
- * otherwise the number of read bytes is returned and <*buf> is moved after the
- * decoded data. See spoe_skip_data for details. */
-static int
-spoe_decode_data(char **buf, char *end, struct sample *smp)
-{
-	char  *str, *p = *buf;
-	int    type, r = 0;
-	size_t sz;
-
-	if (p >= end)
-		return -1;
-
-	type = *p++;
-	switch (type & SPOE_DATA_T_MASK) {
-		case SPOE_DATA_T_BOOL:
-			smp->data.u.sint = ((type & SPOE_DATA_FL_MASK) == SPOE_DATA_FL_TRUE);
-			smp->data.type = SMP_T_BOOL;
-			break;
-		case SPOE_DATA_T_INT32:
-		case SPOE_DATA_T_INT64:
-		case SPOE_DATA_T_UINT32:
-		case SPOE_DATA_T_UINT64:
-			if (spoe_decode_varint(&p, end, (uint64_t *)&smp->data.u.sint) == -1)
-				return -1;
-			smp->data.type = SMP_T_SINT;
-			break;
-		case SPOE_DATA_T_IPV4:
-			if (p+4 > end)
-				return -1;
-			smp->data.type = SMP_T_IPV4;
-			memcpy(&smp->data.u.ipv4, p, 4);
-			p += 4;
-			break;
-		case SPOE_DATA_T_IPV6:
-			if (p+16 > end)
-				return -1;
-			memcpy(&smp->data.u.ipv6, p, 16);
-			smp->data.type = SMP_T_IPV6;
-			p += 16;
-			break;
-		case SPOE_DATA_T_STR:
-		case SPOE_DATA_T_BIN:
-			/* All the buffer must be decoded */
-			if (spoe_decode_buffer(&p, end, &str, &sz) == -1)
-				return -1;
-			smp->data.u.str.str = str;
-			smp->data.u.str.len = sz;
-			smp->data.type = (type == SPOE_DATA_T_STR) ? SMP_T_STR : SMP_T_BIN;
-			break;
-	}
-
-	r    = (p - *buf);
-	*buf = p;
-	return r;
-}
-
 /* Encode the HELLO frame sent by HAProxy to an agent. It returns the number of
  * encoded bytes in the frame on success, 0 if an encoding error occured and -1
  * if a fatal error occurred. */