MINOR: h2: add h2_make_h1_trailers to turn H2 headers to H1 trailers
This function is usable to transform a list of H2 header fields to a
H1 trailers block. It takes care of rejecting forbidden headers and
pseudo-headers when performing the conversion.
diff --git a/include/common/h2.h b/include/common/h2.h
index 2927011..c4b0083 100644
--- a/include/common/h2.h
+++ b/include/common/h2.h
@@ -178,6 +178,7 @@
/* various protocol processing functions */
int h2_make_h1_request(struct http_hdr *list, char *out, int osize, unsigned int *msgf);
+int h2_make_h1_trailers(struct http_hdr *list, char *out, int osize);
int h2_parse_cont_len_header(unsigned int *msgf, struct ist *value, unsigned long long *body_len);
int h2_make_htx_request(struct http_hdr *list, struct htx *htx, unsigned int *msgf);
int h2_make_htx_response(struct http_hdr *list, struct htx *htx, unsigned int *msgf);
diff --git a/src/h2.c b/src/h2.c
index 7c6cbee..4dba675 100644
--- a/src/h2.c
+++ b/src/h2.c
@@ -320,6 +320,77 @@
return -1;
}
+/* Takes an H2 headers list <list> terminated by a name being <NULL,0> and
+ * emits the equivalent HTTP/1.1 trailers block not including the empty line.
+ * The output contents are emitted in <out> for a max of <osize> bytes, and the
+ * amount of bytes emitted is returned. In case of error, a negative error code
+ * is returned. The caller must have verified that the message in the buffer is
+ * compatible with receipt of trailers.
+ *
+ * The headers list <list> must be composed of :
+ * - n.name != NULL, n.len > 0 : literal header name
+ * - n.name == NULL, n.len > 0 : indexed pseudo header name number <n.len>
+ * among H2_PHDR_IDX_* (illegal here)
+ * - n.name ignored, n.len == 0 : end of list
+ * - in all cases except the end of list, v.name and v.len must designate a
+ * valid value.
+ */
+int h2_make_h1_trailers(struct http_hdr *list, char *out, int osize)
+{
+ char *out_end = out + osize;
+ uint32_t idx;
+ int i;
+
+ for (idx = 0; list[idx].n.len != 0; idx++) {
+ if (!list[idx].n.ptr) {
+ /* This is an indexed pseudo-header (RFC7540#8.1.2.1) */
+ goto fail;
+ }
+
+ /* RFC7540#8.1.2: upper case not allowed in header field names */
+ for (i = 0; i < list[idx].n.len; i++)
+ if ((uint8_t)(list[idx].n.ptr[i] - 'A') < 'Z' - 'A')
+ goto fail;
+
+ if (h2_str_to_phdr(list[idx].n) != 0) {
+ /* This is a pseudo-header (RFC7540#8.1.2.1) */
+ goto fail;
+ }
+
+ /* these ones are forbidden in trailers (RFC7540#8.1.2.2) */
+ if (isteq(list[idx].n, ist("host")) ||
+ isteq(list[idx].n, ist("content-length")) ||
+ isteq(list[idx].n, ist("connection")) ||
+ isteq(list[idx].n, ist("proxy-connection")) ||
+ isteq(list[idx].n, ist("keep-alive")) ||
+ isteq(list[idx].n, ist("upgrade")) ||
+ isteq(list[idx].n, ist("te")) ||
+ isteq(list[idx].n, ist("transfer-encoding")))
+ goto fail;
+
+ if (out + list[idx].n.len + 2 + list[idx].v.len + 2 > out_end) {
+ /* too large */
+ goto fail;
+ }
+
+ /* copy "name: value" */
+ memcpy(out, list[idx].n.ptr, list[idx].n.len);
+ out += list[idx].n.len;
+ *(out++) = ':';
+ *(out++) = ' ';
+
+ memcpy(out, list[idx].v.ptr, list[idx].v.len);
+ out += list[idx].v.len;
+ *(out++) = '\r';
+ *(out++) = '\n';
+ }
+
+ return out + osize - out_end;
+
+ fail:
+ return -1;
+}
+
/* Parse the Content-Length header field of an HTTP/2 request. The function
* checks all possible occurrences of a comma-delimited value, and verifies
* if any of them doesn't match a previous value. It returns <0 if a value